Types of Placer Wash Plants

PlacerGold Equipment May 12, 2022alluvial, Atlin, Cariboo, falcon concentrator, gold, gold kacha, gold mining, gold mining equipment, Klondike, knelson concentrator, mining, placer, screen deck, sluice box, suction dredge, trommel, vancouver, wash plant, yukon 1 Comment

There are many different types of washplants on the market today. The one thing that they all have in common is that everyone says theirs is the best! We’re not setting out to prove which plant is the best, this article will explore different types of plants and their strengths and weaknesses. Different plants are suitable for different conditions. There is no one size fits all solution.

There are 4 main components to a wash plant: Scrubber, Concentrator, Feed System, and Carrier. While no two wash plants are identical they all involve a combination of these 4 components.

Take a typical trommel plant that you would find in BC or the Yukon for example. You’ll have a hopper that is fed by an excavator, a trommel that feeds a sluice box and it’s mounted on skids.

Scrubbers

The scrubber is the component of a wash plant that separates raw material and prepares it for concentration. The scrubber will remove large rocks and break down chunks of clay and packed sand. Most scrubber systems use water jets to wash the gravel to remove the fine gold that is attached to the cobbles.

The sand and clay that adheres to pebbles and rocks has been shown to have much higher gold content than the gravel as a whole. For that reason, it is important to wash your material well so that gold can be captured in the concentrator.

The scrubber has three main functions:

Separate large cobbles and boulders from the feed gravel
Wash the cobbles and gravel
Break up clods of agglomerated material

The five categories of scrubbers in use today are the Screen Deck, Trommel, Reverse Trommel, Derocker, and Grizzly.

Trommels

Trommels use a rotating drum to agitate the material. Raw gravel is fed at one end and passes over openings in the drum. Rocks that are larger than the openings are disposed of as tailings. The drum is set at a slight angle to allow the tailing rocks to work their way off the end. Trommels do an excellent job of breaking up clay, mud, and compacted gravels.

A trommel is driven by an electric or gasoline-powered motor. The motor spins the drum by either using a long chain with cogs welded around the drum or by wheels that the drum sits on. Most trommels will have a spray bar running inside the drum that sprays high-pressure water on the gravel to aid in removing gold particles from the rocks. The trommel has a lot of moving parts which is one drawback. The more complex a system is, there more potential for failure.

In North America trommels are most often paired with a sluice box that is positioned at a right angle to the drum. A section of openings are positioned above the sluice box with metal screens to allow specific sizes of particles through. Each mine has different requirements for particle sizes depending on the size of gold that exists there. Miner’s typically have openings of 1/2″ or 3/4″, the size of the opening depends on the distribution of gold sizes in the pay gravels.

Trommels can be paired with any type of concentrator, it doesn’t have to be a sluice. Trommels can be any size. They vary from the Gold Cube trommel which is 5” in diameter and 16” long to plants that can run hundreds of yards per hour with diameters of 8 feet or more. Trommels are relatively easy to set up and can handle a wide range of materials. The big advantage that they have over other scrubbers is the ability to break up cemented or compacted material.

Pros	Cons
Can handle different kinds of material	Mechanically complex, requires maintenance
Can handle high volume	Large footprint
Relatively easy setup	Burn a lot of fuel
Breaks up clay and compacted gravel	Large trommels are difficult to move

Screen Decks

Screen decks use a series of vibrating screens and water jets to wash gravel and separate large rocks. Each deck is mounted on an angle and suspended by springs and caused to vibrate by mechanical means. There can be multiple decks used or just one.

Like a trommel, screen decks are fed at one end and allow oversize material to fall off the other end. There are perforations in between which allow material to fall through to the lower section. The vibration is caused by the rotation of an unbalanced weight called an “exciter”. That is actually the same thing that causes your cell phone or an Xbox controller to vibrate just on a much larger scale. The exciter is driven by a gas or electric motor. Some smaller models such as the Goldfield Prospector drive the exciter by a pelton wheel using water power alone and no motor.

A series of high-pressure water jets are used to wash material as it vibrates. Screen decks allow for well-positioned water jets to be put in place for thorough washing of gravels and rocks. There are a variety of screen options varying from woven wire, to punch plates and rubber or plastic perforated material. Screen sizes vary depending on the gold distribution and material being processed, customization of screen sizes is easy to achieve.

Screen decks can accomplish very high production in the right materials. Some of the largest wash plants in the world are using screen decks for that reason. Unlike a trommel, screen decks do not handle clay or compacted material very well. It tends to bounce off the screens and roll off the end. Despite the violent nature of vibrating beds the screen deck is a relatively simple machine and does not require a lot of maintenance. The only part that is mechanically driven is the exciter and there aren’t a lot of moving parts compared to a trommel or a derocker.

Screen decks tend to be quite high off the ground (at least large scale wash plants). They generally require enough of an elevation difference at the site to be able to feed the hopper and allow room for a concentrator below. Some miners use a conveyor system to get around this problem but mobility is not the screen deck’s strong suit. They work best in a stationary position where they will be used for a long period of time.

Pros	Cons
High volume	Struggles with clay and compacted material
Mechanically simple	Large footprint
Fuel-efficient	Difficult to move
Separation of multiple sizes	Slow to set up

Reverse Trommels

There are a few variations of reverse trommels that work a little differently than a basic trommel. A reverse trommel allows heavy material (ie. gold) to exit one end while the large rocks and waste material exit the other. Reverse trommels often have a double tube design with an inner trommel that screens the material while the outer trommel has a screw-like helix that separates the gold.

The trommel is set at the appropriate angle to allow gold to exit one end while water flows over the outer tube. The helix acts in a similar way to a gold wheel, the material of higher density is allowed to work it’s way up the spiral and exit on one end, the less dense material falls out the other.

There are some models with only one opening that kind of resembles a cement mixer. The APT RG-30 for example. They work in a similar way with a helix and a carefully positioned angle and rate of water flow.

Reverse trommels are popular in the mid-sized range from 1 to 10 yard per hour units. There are quite a few on the market. One popular unit is the Mountain Goat Trommel which is a hobby-level clean-up machine. There are large-scale commercial versions and everything in between.

Reverse trommels are interesting machines and work well once they’re set up but they are much more complicated machines than a basic trommel and are finicky to set up. They also require a lot of maintenance. That’s one reason they are mostly on the small-scale side of the industry.

Pros	Cons
Can produce very clean concentrate	Require a lot of maintenance
Break up clay very well	Slow setup
Separation of multiple sizes	Complicated machinery, lots of moving parts
Some designs are very compact	Not very fuel-efficient

Derockers

Derockers are a neat machine. They use a flexible deck made of long flat slabs with spaces between them. Under the deck is a carriage frame with truck tires that moves back and forth. There is a high-pressure spray system overhead that washes all the material. As the undercarriage moves back and forth it rolls the rocks around on the deck. The water and rolling action work together to wash off the rocks and allow smaller-sized pebbles and material to fall through the openings in the deck slats (usually 2” minus).

Derockers work really well in areas where there are a lot of large rocks and slabs. They are called “de-rockers” after all. They can handle some clay, due to the rolling action they can break it up somewhat. The derocker was invented in the Yukon to deal with gravel deposits that are full of boulders. These machines can easily handle boulders or slabs up to 4 feet in diameter, which would break other types of separation equipment.

Compared to some of the other scrubbers such as screen decks and trommels, the derocker is a complex machine with a lot of moving parts. You have a carriage that takes a beating, the deck has a lot of links to maintain but the derocker frame itself is stationary.

super sluice finger derocker — Super Sluice Derocker in Cariboo, BC

There was a variation of the derocker in the 1980s called the Super Sluice, made by a company called Gold Machines Inc, that used metal fingers instead of the flexible deck. The Super Sluice was very popular for about 10 years in the Cariboo, Klondike and Atlin but over time the complexity of the machine led to frequent breakdowns and they are very few still in use today.

Pros	Cons
Handles large boulders and slabs	Require a lot of maintenance
Can break up clay and compacted material	Complicated machinery, lots of moving parts
Very high production with the right material	Require a lot of water and power to run
Quick setup, easy to feed	No adjustment for screening options

Grizzly

Some wash plants don’t have a mechanical separation system at all, some use a simple grizzly. A grizzly consists of vertical bars with spacing to allow the size of material you want to pass through. The grizzly is set on an angle such that the larger rocks will roll off and the stuff that fits through the bars will pass through.

Highbankers and small test plants use a grizzly. Production is slow and they often require manual intervention to clear the large material that collects below. Grizzlys are often incorporated into other separation equipment such as screen decks and trommels.

Pros	Cons
No moving parts, no breakdowns	Slow production
No motors needed	No ability to clear tailings
Easy to move, no setup required	Screened material is still coarse
Easy to change for different size of gravel

Concentrators

The concentrator is the heart of a washplant. It’s the part of the wash plant that catches the gold and other dense material.

Placer concentrators all use gravity and inertia to separate material based on density. Gold is very dense, it has a density of 19,300 kg/m³. That means that one cubic meter of gold would weigh 19,300 kilograms (19.3 metric tons). In contrast, the typical gangue minerals such as quartz sand have a density of 2,700 kg/m³ and the black sands have a density of about 5,200 kg/m³.

All concentrating methods depend on this principle, except for the use of mercury but that’s not used in large-scale placer mining.

The Sluice Box

In North America, the sluice is the most common concentrator on commercial placer gold wash plants. The sluice box was developed during the California gold rush around in 1849. The first sluices were called Long Toms. Early sluice boxes consisted of long wooden boxes with wooden riffles and moss or burlap to line the bottom. The primitive long toms saved a ton of labour but miners at that time did not have a pre-scrubber and had to pick all the rocks out by hand and pan all the concentrates.

Modern sluices haven’t changed that much from the original design. We use metal now and have scientific studies to analyze the optimal riffle designs and matting but the concept is exactly the same.

Sluices work by creating a vortex behind the riffles. As the gravel/water slurry flows over the riffle it creates an eddy current as it rolls back on the riffle. The eddy causes the water to momentarily lose inertia and it can no longer carry the dense sediment. Dense material is held in the riffle as long as the water is flowing. Once the water stops, the suspended material is released from the riffles, that’s why it’s not good to stop and start a sluice box.

There are a variety of riffles in use today but they all work the same way. There have been some excellent studies on different riffle designs and matting.

A study of the fine gold recovery of selected sluice box configurations, Jamie Hamilton at UBC: download PDF
Placer Gold Recovery Research by Rany Clarkson of New Era Engineering: download PDF

Studies show which riffle designs work the best, what spacing between riffles is optimal and what angle to run at, typically 1.5 to 2.5 inches/foot of sluice run.

There are several different types of riffles in use today. The Hungarian riffle and expanded metal are most common in commercial sluicing operations. Miners in New Zealand developed the hydraulic riffle in the 90’s that allows water to inject under the riffle which keeps them from packing. It’s similar to the way that the Knelson concentrator uses a fluidized bed, more on that later in this article.

Some modern designs have abandoned riffles altogether and use a drop riffle or vortex such as the Devin Sluice or Dream Mat. These vortex systems catch gold in spirals carved into the matting or machined into aluminum sheets. Vortex riffles and matting have the advantage of quick clean-ups but they tend to work better on small-scale operations and clean-up sluices.

Different types of matting are used to catch fine gold. Miner’s moss is a typical matting that is made of a synthetic material with lots of loops to catch gold. Miner’s moss is kind of like a thick version of the soft side of velcro or thick carpet. Actual carpet is used in some cases as well. There are lots of high tech rubber designs on the market such as Gold Cube matting, Gold Hog, Dream Mat and many other designs. Some matting is easier to clean up than others but they all catch gold.

Other variations on the sluice include the live bottom and oscillating sluices. The live bottom box works really well. The live bottom box uses a thick rubber sheet on the bottom of the sluice box and has mechanized rollers that sort of massage the rubber moving it up and down. Similar to the rollers in a massage chair. That keeps the material from packing up and keeps the gold at the bottom.

Sluice boxes can handle huge scale production, they can be made very large and multiple sluices can be run together to handle even higher production. The largest wash plants in the world run multiple sluices. All sluices require careful setup and lots of tweaking to make sure they’re catching all the gold. Sluice riffles will eventually become packed with black sand and can no longer catch gold, for this reason, a sluice must be cleaned out regularly.

Despite the ubiquity of sluices and their simplicity an alarming number of commercial miners are losing fine gold off the end of their sluice. Quality control and testing is essential to make sure that your sluice is operating as it should be. A full-scale sluice can reliably capture gold down to 150 mesh with proper setup.

Sluices have the major disadvantage of slow cleanup times that require a full shutdown. They also lose gold when you start and stop the slurry feed. They are simple and easy to repair in the field though.

Pros	Cons
Can handle large volume	Proper setup is critical
Simple design, easy to fix in the field	Require shut down for cleanup
Modifications and adjustments are easy	Large footprint on commercial operations
	Require frequent cleanups

Hydrostatic Jigs

Hydrostatic Jigs, often just called “jigs” are very different than a sluice. They use a pulsating water action to separate gold from the lighter gangue materials. Jigs have serval components that work together to separate gold. Typically they have a screen in the upper section which holds a layer of steel balls called “ragging”, usually about 3” thick. Below the screen and ragging is a rubber diaphragm that is moved up and down rapidly by mechanical means producing a vertical pulsing action. The feed material flows over the screen is allowed to settle into the ragging.

The pulsing action in combination with the steel shot allows dense materials to settle to the bottom while lighter material is forced up and carried away by the flow. The action of the jig is based on Stokes Law which determines the rate at which particles fall while suspended in a fluid based on their density. Jigs are usually arranged in a series of cells, each with its own screen and diaphragm. Any number of cells can be used in combination to increase capacity.

The gold is stored in a container in the bottom called a “hutch”. One advantage to this system in commercial operations is that gold nuggets and pickers are not sitting in the open as they would be in a sluice box so it would be difficult for an employee to steal the gold.

Jigs first came into use in placer mining in 1914 in California. They were soon adopted to the large floating dredges that were in use at the time. Jigs had several advantages over sluice boxes. First, they take up much less space, which was important on a floating dredge. Secondly, they can be cleaned out without having to shut down the operation. You simply need to drain out the hutch and you’re back in business.

One of the first jigs used in placer mining was the Pan American Jig wich consisted of two cells. The Pan American model had two 42-inch square cells and could process 20 yards per hour. Multiple units were used in tandem to increase capacity.

Many modern jigs follow the exact same design as the Pan American. Many manufacturers around the world still produce an almost identical machine. There are many variations of jigs today but they allow work on the same principle. Smaller jigs are often used for cleaning concentrates but larger units are also used in full-scale commercial operations.

Pros	Cons
Clean up without shutting down	Initial setup requires lots of tweaking
Small Footprint	Rubber diaphragm wears out
Gold stored in safe container	Low capacity per cell
Dummy proof once set up	Specialised parts required

Centrifugal Concentrator

Centrifugal concentrators are the most efficient method for concentrating placer gold in terms of capturing fine gold and overall revocery. They rely on a rotating drum that resembles a washing machine. The drum spins at high RPM, usually at least 100 RPM, creating a centrifugal force that pushes heavy elements to the outer edge. If you’ve ever ridden the gravitron ride at an amusement park you’ll know firsthand how this works.

In a centrifugal concentrator, the lighter material is allowed to flow over the top of the bowl and is discharged as tailings, the dense material is held in riffles and retrieved during cleanup. The principle is similar to a hydrostatic jig except more G forces are applied. At high G forces centrifuges are less sensitive to particle size than other gravity methods (sluice, jig, etc) and as such can retrieve extremely small gold grains down to 400 mesh.

There are four types of centrifugal processors on the market today: the Knudsen Concentrator, Falcon Concentrator, Knelson Concentrator, and the Gold Kacha.

The Knudsen was the first centrifugal concentrator used in placer mining. It was invented by George Knudsen of California and patented in 1942. The Ainlay bowl was patented in 1928 and saw some experiments in placer mining but didn’t take off. The Knudsen bowl is a 12” to 36” diameter bowl mounted on a vertical drive shaft. The bowl is tapered to allow the slurry to rise up the side while the riffles catch the gold. The Knudsen bowl was used all over the world most notably in California, New Zealand and in Africa. The Neffco Bowl is a modern version and is still used today.

The Knelson Concentrator was developed in Burnaby, BC in 1980. The Knelson is a bit more complex than the Knudsen Bowl and runs at a higher RPM. The Knelson concentrator uses a perforated cone and uses pressurized water that forces in from the outside of the bowl. The cone experiences a force of 60G’s while the water pushes against it, the counteracting force acts to keep the heavy particles fluidized allowing a continual replacement of light grains by heavy ones and avoiding the compaction of riffles like you see in a sluice. The Knelson concentrator is very efficient but like all centrifugal concentrators it requires frequent cleanups.

Falcon concentrators are similar to the Knelson. The main difference is the angle of the walls. Both use the same water pressure system that pushes against the centrifugal force creating a fluidized bed. Falcon (now called Sepro Mineral Processing) is based in Langley, BC, and was founded in 1987. It’s interesting that both Knelson and Falcon were developed in Greater Vancouver. Both companies are world leaders in mineral processing technology.

The Gold Kacha (GK) is a really cool system. I was introduced to this device on a recent placer exploration trip to Sierra Leone, Africa. The Gold Kacha was developed in 2005 in South Africa by Appropriate Process Technologies (APT). It’s similar to the Knudson/Neffco bowl but has several advantages. The Gold Kacha can easily process gold down to 450 mesh (30 microns) and the riffles are designed to prevent gold compaction. The GK can run 3-4 cubic yards per hour.

It’s set up in a turnkey package that’s easy to use. The biggest advantage is that the Gold Kacha retails for $1,500 USD. All the other concentrators on this list are at least 4 times that cost but the GK was designed for use in third world Africa to help artisanal miners avoid using mercury.

All centrifugal gold processing machines work well for catching very fine gold, they catch coarse gold too but the fine gold is the challenging part. Centrifugal processors can catch extremely fine gold very well but they require frequent cleanups, usually every hour or so. Some wash plants use multiple centrifuges and are able to isolate them using valves so that while one centrifuge is being cleaned the others are still operational, I think we’ll see more of these systems in years to come.

Pros	Cons
Able to retrieve gold < 400 mesh	Frequent cleanups are required
Easy to use, no special knowledge required	Very expensive (except Gold Kacha)
Low water consumption	Low capacity per unit (compared to sluice)
Low power/fuel consumption	Requires thorough pre-screening and clean water

Spiral Concentrators

Spiral concentrators are not commonly seen at placer mines these days. They were popular in the 70s and 80s but have fallen out of fashion. They are very commonly used in the beneficiation of heavy mineral sands, chromite, tantalite, iron ores and fine coal.

Basically, spiral concentration involves a stack of spirals that are fed from the top using a low-pressure slurry pump. The slurry flows down the spirals like a water slide and separates based on density. At the bottom there are splitters that divert the slurry at different points along the radius of the spiral. The outside of the spiral will have the tailings, since they are less dense the spiral action forces them to the outside, the concentrated gold is on the inner radius and the “middlings” are in the middle. The principle is similar to the way that a shaker or wave table separates gold.

Spirals are often run several times so that the middlings can be run again to increase their level of concentration. There are several variations such as the pinched sluice and the Reichert Cone which uses a series of stacked cones instead of spirals. The spirals are usually made of fiberglass and are lightweight and fairly inexpensive. They are able to reliable capture gold from 6 to 200 mesh, some models can catch down to 300 mesh. Placer spiral systems can handle 4-10 yards per hour but can be scaled up with more units.

Pros	Cons
Able to retrieve gold < 300 mesh	Require consistent, laminar flow
Easy to use, no special knowledge required	Low capacity per unit (compared to sluice)
Low cost and cheap to operate	Requires thorough pre-screening
Low power/fuel consumption

Dry Washers

Gold is found in areas that don’t have water available, such as the desert regions of California, Nevada, Arizona, and Australia. Placer miners came up with a solution for dry washing.

The process works on the principle of winnowing, which uses wind or air to separate dense material from less dense material. The technique has been used for millennia to separate grains from their husks. Dry washers use a short, waterless sluice and pressurized air in combination with vibration. The sluice portion of a dryswasher has a porous bottom, either canvas or a very fine screen, that allows air to pass through. The whole thing is set on a steep angle so that the material can work its way over the riffles. Air blows up from the bottom and provides some buoyancy for lighter material.

Small scale dry washers resemble a highbanker with a screen/grizzly on the upper section and a sluice-like screen setup on the bottom. There are hand-operated units using bellows, and gas-powered blowers. Commercial-scale drywasers are somewhat rare but they are used in gold-rich areas of Australia and parts of the United States.

There are no manufacturers that make commercial-scale dry washers. All large scale units are custom made. Most of them are fed by a loader and distribute the material through a screen system into multiple cells of smaller dry washer sluices. Keene is developing a commercial drywasher but it’s not available at this time.

Material to be run in a drywasher must be completely dry, it must contain less than 3% water otherwise it won’t work. The material must also be disintegrated and not clumped together by clay or caliche. Studies show that under ideal conditions a dry washer will have about 15% less recovery than a wet system (ie. sluice).

Pros	Cons
Doesn’t require water	Lower recovery than wet systems
Can be moved rapidly	Makes a lot of dust
Fast cleanup (compared to wet sluice)	Frequent cleanups are required

Feed Systems

We’ve covered screening systems and concentrators. The next component of a wash plant is the feed system. Wash plants can be fed in different ways. Some have a hopper that is fed by an excavator or loader, others are fed by a slurry pump or dredge.

Hoppers

The most common feed system on a wash plant is the hopper. The hopper is a large container that is filled with raw gravel and allows it to be dispersed at an even rate. Many hoppers are gravity-fed, they operate in a similar way to an hourglass. They have an inverted pyramid shape and act as a funnel.

Other hoppers have a belt or track in the bottom that manages the feed rate. I’ve seen some cool designs in the Yukon that use a recycled excavator track in the bottom of the hopper to slowly feed a trommel.

The hopper won’t feed itself and must be refilled regularly by an operator. Most operations either use an excavator or a front end loader to keep the hopper full. Some miners use a conveyor belt system in combination with a hopper to maintain an even flow of material.

Pros	Cons
Maintain even flow (when not clogged)	Large rocks can get stuck
Simple design, not much to break down	Requires operator to refill regularly

Bucket Ladder

The bucket ladder is the most efficient system for feeding wash plant. This was the norm on the monster floating dredges that scoured the gold-bearing placers of western North America from the late 1800s till the 1950s. These monster dredges moved ridiculous amounts of gravel, each dredge could efficiently process up to nine tons of gravel per minute, with an average of 20,000 cubic yards per day!

The bucket ladder consists of a boom and a series of metal digging buckets. It’s sort of like a giant chainsaw. The buckets are specially designed with a digging edge and held together with a giant chain. The boom is raised up and down with a gantry winch system. The buckets continually dump material into the scrubber system (trommel, screen deck or any other system that we discussed above).

The depth of the bucket line is limited to the length of the boom. Typical industrial dredges could dig up to 60 feet deep. The buckets are able to dig up soft bedrock but if hard rock is encountered they cannot. The buckets can’t handle large boulders either. The dredge in the video below isn’t at a placer mine but it shows what a modern bucket ladder dredge can do.

Environmental restrictions have made it a lot more difficult to operate a floating plant with a bucket line but some are still in operation today in Europe, Africa, Russia, China, Asia, South America, Mexico and the Yukon. Modern bucket ladder dredges are common in non-placer applications

Pros	Cons
Constant supply of material	Can’t dig too deep
Huge capacity	Massive overhead cost
Excavation and delivery in one step	Not very mobile
Few breakdowns	Regulatory hurdles

Gravel Pump

One of the most efficient ways to feed a wash plant is with a gavel or slurry pump. There are several large-scale placer mines in Alaska and other parts of the world that mine by hydraulic means using large water monitors. The material is washed into a pit and pumped up to the wash plant using large industrial slurry pumps.

Gravel pumps don’t work in every scenario but if your location is favorable this is a very efficient way to mine. The slurry pump can be unmanned, saving labour costs and allowing workers to focus on other areas of the mine. These pumps are very expensive initially but the savings in operating costs will pay off over time.

There are a lot of mines operating in wet ground in BC and the Yukon and a slurry pump would be an excellent solution. Instead of fighting the groundwater you can use it to your advantage.

Pros	Cons
Consistent feed of material	High initial cost
High capacity	Requires careful mine planning
Savings on labour	Doesn’t work in every location
Good solution for wet ground	Possible regulatory hurdles

Suction Dredge

Suction dredges are similar to a slurry pump set up. A suction dredge uses a venturi to create a vacuum that sucks up gravel and water at the same time. Floating dredges are commonly used in small to mid-scale mining. Floating dredges are classified by the diameter of the suction hose which varies from 3 to 8 inches.

Modern suction dredges first became popular in the 1950s due to the availability of good, portable, centrifugal water pumps and modern diving equipment. Some jurisdictions such as British Columbia and parts of California have banned suction dredging but it is a very efficient method that is used around the world.

There are some very advanced dredge machines on the market today. Large scale operations are using 8-inch and larger suction lines. Some of the most interesting dredge innovations are being developed for use on the Bearing Sea in Alaska. The robot dredge in the picture below is a really cool new technology that uses a remotely operated robot with a cutting head attached to an 8-inch dredge.

Not all dredge systems use a floating platform and can be fitted to just about any wash plant. You can get excavator-mounted units up to 12” in diameter that can be used in a regular mining pit. These systems advertise up to 600 cubic yards per hour of production.

Some systems use slurry pumps instead of a venturi in combination with a cutting head. The advent of undersea mining has pushed the envelope on this technology and we’re going to see a lot of advancements in the coming years.

Pros	Cons
Consistent feed of material	Doesn’t work in every location
Excavation and feed at the same time	Possible regulatory hurdles
Can be unmanned

Wash Plant Carriers

This is the part of the washplant that supports the scrubber, concentrator, and feed system.

Stationary Skids

Many large wash plants are mounted on a steel frame welded to metal skids. This system isn’t very mobile. Skid-mounted plants are meant to stay in one place for a long time. When it’s time to move they are pulled by heavy equipment such as bulldozers or large excavators and dragged into position.

Skids are simple and stable but don’t provide a lot of mobility.

Trailer or Frame with Wheels

Small to mid-sized wash plants can be mounted on a trailer or frame with wheels. This provides an easy way to move it around. The trailer will often have a leveling apparatus to stabilize the plant while in use. Not much else to say, it’s a trailer we all know what that is.

Floater Plant

The floater plant, also known as a “Doodlebug” is a very efficient way to mine. The plant can be mounted on pontoons or a barge. Floater plants have the ability to move very rapidly in a pond of their own making. It takes planning to operate efficiently without boxing yourself in but when properly executed a floater setup can move a lot of material quickly.

Any type of scrubber, concentrator, and feed system can be fitted onto a floater.

The large bucket line dredges technically fall into this category but most floaters today use an excavator to dig and pull the barge. For a floater operation to work effectively the ground can’t be too deep. Floaters mine in one continuous direction mining in front of the plant while the tailings are deposited behind. It’s almost like an assembly line approach to placer mining.

Pros	Cons
Rapid movement	Don’t work in deep ground
Efficient mining and tailings management	Require a pond for the plant to float on

Floater Wash Plant Atlin Yukon — Floater Plant in Atlin, BC

A placer wash plant is the sum of its parts. It’s not a trommel, it’s not a sluice, it’s the whole package. There are just about as many combinations as there are miners. Placer miners are always coming up with new innovations to solve problems and mine more efficiently.

There is no one plant that is the best in every situation. They all have their strengths and their weaknesses. The type and size of your gold, the type of gravels you’re dealing with, ground conditions, regulatory environment, available capital, and other factors all work together to determine what type of wash plant is best for your mining operation.

Drone Mapping of a Coal Mine

PlacerGold Drones April 18, 2016drone, DSM, lidar, mining, mining drone, orthomosaic, point cloud, uav, vancouver, Vancouver drone 1 Comment

West Coast Placer was contracted to conduct high resolution aerial drone mapping of a coal mine in Alberta, Canada. We were hired by the environmental department to map two parts of the coal mine to aid in their reclamation efforts. We produced high resolution imagery and 3D models.

With our fixed wing mapping drone we were able to produce several custom mapping and imagery products. We made a beautiful high resolution orthophoto, a digital surface model (DSM) with topographical accuracy up to 30cm, a LAS format point cloud and one more 3D model. We were also able to format the 3D data so that it could be used in their mine planning software (Minesight).

Two sections of the mine were surveyed. We flew a total of three flights in the same day. The mine asked to have the main pit flown two times to confirm the accuracy and repeatability of the data. We were happy to oblige and of course the flights matched within 2cm of each other. Each section that was flown was about 2 square kilometers and our drone has the flight duration to cover each section in one flight.

The photo quality on the still photos and orthomosaic was outstanding. We were able to achieve an image resolution on the georeferenced mosaic of 4cm/pixel. That means that each pixel in the photo represents a real world footprint of 4cm by 4cm. That kind of resolution cannot be matched by current satellite imagery providers. Actually they are not even in the same league. The best satellite imagery that you can buy today is provided by WorldView-3 satellite and has a resolution of 31cm/pixel. It also costs a lot of money. Google Earth come in at a pitiful 65cm/pixel in the best locations.

Here are some examples of our imagery. First is a shot of the truck that we used as a base station for the drone. You can clearly see the truck, the two operators and even the pickets in the bed of the truck. You can click on these images for a larger view.

Here is a Google Earth image of the exact same location. I love Google and everything that they do but this image is just no comparison. To start with it’s three years old (despite the 2016 copyright note at the bottom), the mine does not even look like that today. The resolution is so poor that you can’t even tell what you’re looking at.

Here are a couple more shots from the same flight. You can clearly see this orange excavator and other details.

The 3D data is also incredible. Check out the video below for a great example of the 3D data that we produced. That video shows a virtual fly though of a LAS point cloud. LAS is the same format that LiDAR data produces.

Drone technology is just making it’s way into the mining world. With the low cost and amazing imagery it is a no brainer for many applications. In the case of this coal mine the environmental team now has excellent data to aid in their reclamation planning that would not have been available only a couple years ago. Check out this post on drone applications in mining.

Our client was very happy with the products that we produced especially for the price. Check out our Drone Services page for details on pricing.

Harrison Lake Adit Exploration

PlacerGold Trip Reports April 1, 2016gold, gold mining, gold rush, lode gold, lost mine, mining, vancouver 5 Comments

Last week my neighbour phoned me and asked if I wanted to go on a road trip to check out an adit by Harrison Lake. Of course I said yes. Who wouldn’t be down for a short road trip to check out an old mine adit.

The trip only took two hours from my home in Abbotsford, BC. We drove up to Harrison Hot Springs then transitioned to the 4×4 road called Harrison East FSR. Conditions were great for the trip out we got hit by rain on the way back but that’s to be expected on the West coast in March.

I brought along my mountain bike night riding light and it worked awesome! You can see the difference between my super light and a standard headlamp in the video. Check out the video below showing our exploration in the adit:

This adit was created a long time ago, probably a during the period of the Fraser River and Cariboo gold rushes (1860s – 1880s). No records have been found from that time period describing the adit though. During the gold rushes the Harrison was one of the major routes to the Cariboo and many miners worked in the region.

The adit extends for approximately 50m with a slight bend half way in. It cuts through altered schist formations and has several small quarz veins exposed inside. We sampled one of the veins which will be sent to a lab for fire assay. The map below is taken from a 1983 geological report of the area.

In addition to the 50m adit a vertical shaft had also been excavated. Unfortunately the shaft is filled with water so it cannot be explored at this time. Both excavations were carried out to explore a sizable quartz vein. The shaft is right on the 1m wide vein and driven vertically into the bedrock. The adit that we explored was intended to intersect the shaft and the vein. It seems that the miners missed. It is difficult to tell by how much.

Inside the adit there are wooden tracks that line the whole tunnel. These were probably part of an old rail system used to remove the excavated rock. It is not known why the miners abandoned the property, without any information we can only guess. There are other adits in the area that we’ll explore another time. Not bad for a Tuesday afternoon.

How To Program Your Radio for BC’s Backroads

PlacerGold Equipment March 26, 2016baofeng, communication, FSR, programming, radio, vancouver 52 Comments

In the last couple years the BC government has changed the radio frequencies used on all the forest service roads (FSRs). They used to post the frequencies used so that you could type them in to your handheld radio. With your radio programmed you are able to communicate with other users of the road, ie. logging trucks. The radio system is primarily there as a safety procedure to prevent collisions on BC’s narrow backroads. The cryptic system that they are now using takes away that safety tool if you are not prepared.

I was caught off guard in 2015 when the radio frequency was removed from the West Pavillion FSR which I use to access some of my claims. A sign that mentioned the change was in place but it did not state the new channel.

Here is the government site showing which channels are used on which roads: Resource road radio channel maps

This post will help you program your radios for BC’s new RR radio system. You will need a few things for this:

A Radio
Programming Cable
A Computer
Radio Software

I am using a Baofeng UV-5R programmable radio. I can’t say enough good things about this radio. It is inexpensive (~$30), powerful and has lots of memory channels. The coolest feature is that they are field programmable too. More on the Baofeng UV-5R here, Gear Review: Baofeng Handheld Radio. This guide works for other radios such as a Kenwood or Motorola, although you might need different software.

The cable that I’m using is a FTDI 2-pin Kenwood style. It works for Baofeng and Kenwood radios. For this post I’m using my laptop running Ubuntu linux. But this guide will work with Windows too.

The software is really the key to the whole programming procedure. There is an excellent open source program called CHIRP which stands for CHInese Radio Project. CHIRP was designed to make it easy to program cheap Chinese radios such as the Baofeng, it also works on just about any other radio out there and its free.

OK lets get started. The first thing that we have to do is get a list of frequencies. I found them on a government website, but I’ll save you the trouble and post them right here.
You need to download and install CHIRP, on Ubuntu all you have do is run this command:

sudo apt-get install chirp

That will download and install the latest version from Ubuntu’s repositories. If you are running Windows or Mac you can download CHIRP from their website here, CHIRP Site. Installation is easy, just run the .exe file and you’re good to go.

Next start up the program, on linux you need to run it as root (AKA administrator) you can do that with the following command:

sudo chirpw

OK, now that CHIRP is started you have a few options. You can clone your radio’s existing channels and modify them. You can start a new file or load in an existing one. Lets start one from scratch. Click on the File menu and select “New”. In my example I added a couple extra channels at the top.

It’s a pretty straightforward application. The window functions a lot like a spreadsheet, there is a row for each channel and different parameters are defined in each column. The BC RR channels are pretty basic so you can ignore most of the columns. The RR channels are simplex, that means that they use the same frequency for transmit and receive. Most public channels are simplex. They have no carrier tone or any other funny business. So we just have to enter the frequencies and the name. Leave the rest of the settings at the default values.

After entering all 35 channels you are ready to load them onto the radio. To do that first connect the programming cable to the radio. It plugs into the port where you can add an external microphone. See photo below:

Make sure the radio is turned off when you connect the cable. Otherwise it could shock the memory and wreck the radio. The software will need to know which serial port you have connected to. In linux you can get that information with the following command:

dmesg | grep tty

Look for the line that looks like this:

[147117.481257] usb 2-3: FTDI USB Serial Device converter now attached to ttyUSB0

That is telling us that the programming cable is on port “ttyUSB0”. In Windows the easiest way is to look at your serial ports in the device manager.

Now you can upload the channels to the radio. Turn on the radio with the programming cable attached. Then choose “Upload to radio” from the Radio menu in CHIRP. You’ll be prompted for the serial port, in my case ttyUSB0. You will also need the radio make and model.

Once you hit OK, the upload will begin. You’ll get a nice progress bar to show you how its going.

That’s about it. Make sure that you turn off the radio before you disconnect the programming cable. Now you’re ready to hit the back roads and communicate with other travellers.

Update on Laws Regarding Programmable Radios 2021

There has been a lot of feedback about this post stating that Baofeng radios are illegal, you need a license, and things of that nature. We were recently contacted by a representative of Innovation, Science and Economic Development Canada (ISED, formerly Industry Canada) and we’ll share the factual information here.

First of all, it’s not illegal to program your own radio in Canada. ISED wants you to have a license for the channels that you are using though.

Most of the regulations in the Radiocommunication Act depend on two principles.
1) Radio spectrum is a limited resource
2) Prevention of “Harmful Interference”

ISED likes to state that the radio spectrum is a limited resource. What does that really mean? Well, there is a limit to the number of frequencies that can be used in a particular area without having overlapping signals. Spectrum management is important in congested areas to maintain quality for all users. This is one of the main goals of ISED. They regulate a lot of radio stuff beyond VHF frequencies on backroads, including cell towers, police and military communication, maritime communication, aviation, and other wireless transmissions. Managing wireless radio is important for our society to function properly. Calling it a “limited resource” is a little weird but management of the frequencies that are being used is important.

According to the ISED representative that contacted us the reason for most of the regulations is to prevent harmful interference. This is the definition that was provided by ISED:
“Radio interference is an adverse effect that could degrade, obstruct or interrupt the use or functioning of a radio. Radio interference can happen for a variety of reasons, and most of the time they are unintentional. In certain situations, the interference can be harmful.

Public safety agencies are critically dependant on their radio systems to provide services to the public. When their radio systems are interfered with, the ability to protect and serve the public is impaired, leaving human lives and property at risk. Non-public safety operations can be negatively impacted by degradation or repeated interruptions to radiocommunication systems. In some cases the interference may not be harmful, but it could still reduce the quality and usability of a radio system. When providing access to spectrum and regulating its use, ISED seeks to maximize the economic and social benefits that Canadians derive from the spectrum, and minimizing interference is a key part of this objective.”

The Radiocommunications Act defines harmful interference as follows:

harmful interference means an adverse effect of electromagnetic energy from any emission, radiation or induction that

(a) endangers the use or functioning of a safety-related radiocommunication system, or

(b) significantly degrades or obstructs, or repeatedly interrupts, the use or functioning of radio apparatus or radio-sensitive equipment;

OK, that’s some background on the laws. So what does that have to do with Baofeng radios and using them to communicate for safety reasons on BC’s backroads? The short answer is nothing.

If a radio is programmed correctly it won’t interfere with other radios and won’t cause “harmful interference”. A Baofeng radio is fully capable, and often much more capable, than a Kenwood, Icom or Motorolla that you can purchase from a certified radio shop. We’ll see some of the specific laws below.

Radio equipment in Canada requires licensing. There are two areas where a license is needed. The radio itself needs to be certified, this is usually done at the manufacturer level. Radios that aren’t certified by the manufacturer are required to have a license issued for its use. The criteria for obtaining such a licence is available here: RSS-119 – Land Mobile and Fixed Equipment Operating in the Frequency Range 27.41 – 960 MHz.

Baofeng radios cannot be licensed in Canada because they allow the user to program frequencies with external controls. That goes against Section 3.2 of the Radio Standards Specification

3.2 Transmitters With External Frequency Selection Controls
In order to prevent radio interference caused by end-user transmissions on unauthorized frequencies, transmitters with external frequency selection controls and/or frequency programming capability shall conform to the following:

(a)Transmitters with external frequency selection controls shall operate only on authorized channels which have been preset by the manufacturer, equipment supplier, service technician or maintenance personnel.

(b)Transmitters with frequency programming capability must have at least one of the following design characteristics, which prevent the user from altering the preset frequencies:

Transmitters with external controls available to the user can only be internally modified to place the equipment in the programmable mode. Furthermore, while in the programmable mode, the equipment is not capable of transmitting. The procedure for making the modification and altering the frequency program is not available to the user of the equipment.

Transmitters are programmed for frequencies through controls that are inaccessible to the user.

Transmitters are programmed for frequencies through the use of external devices or specifically programmed modules that are available only to the service technician or maintenance personnel.
Transmitters are programmed through cloning (i.e., copying a program directly from another transmitter) using devices and procedures that are available only to the service technician or maintenance personnel.

Since the Baofeng radios cannot be licensed use of these radios contravenes subsection 4(1) of the Radiocommunication Act which states:

4 (1) No person shall, except under and in accordance with a radio authorization, install, operate or possess radio apparatus, other than

(a) radio apparatus exempted by or under regulations made under paragraph 6(1)(m); or

(b) radio apparatus that is capable only of the reception of broadcasting and that is not a distribution undertaking.

According to ISED violation of Section 4(1) can carry a potential fine up to $250. Although that is really just academic since they don’t actually enforce that law.

According to ISED, for a radio using RR and LADD channels, a radio license is required. ISED will only issue a radio license for a radio that is certified and meets the certification requirements. A certified radio should display an IC number on its label (usually this is next to the FCC number). The conditions of use for RR and LADD channels are noted here: RR — British Columbia Resource Road Channels and B1 — Western and Northern Canada Mobile-Only Frequencies.

An ISED radio license costs $42.65/year per radio and is valid from April 1 to March 31 (the following year). This is a flat fee and not dependant on the number of channels.

Operating without a license can theoretically face fines if ISED finds out that you are doing so and has your contact information. You can see the potential fines under the Administrative Monetary Penalties (AMP).

According to the AMP penalties, operating without a license carries a potential fine of $1,000 for the first offense and up to $2,000 for the second offense.

Here’s the kicker though and this is really important, ISED depends on “voluntary compliance”. I asked the representative from ISED for evidence of fines that have been given out in the past and he confirmed that they don’t actually give out fines. They have no means to enforce these laws and do not check what radios people are using. There have been rumors on certain 4×4 groups that ISED sets up roadblocks on FSRs to catch people with illegal radios. Those rumors have been confirmed to be false by the ISED.

It seems odd that the FSR roads are open to the public but the Canadian government is limiting access to radio use by means of a licensing program. It’s also odd that they go out of their way to prevent users from using an inexpensive field-programmable radio. ISED’s explanation of “harmful interference” is ridiculous. In reality, you are protecting yourself and other road users by having communication available.

In summary, there are laws regarding field-programmable radios but they are not enforced. Similar to how there are laws regarding downloading movies or consuming fake maple syrup (actually, that law was repealed in 2019).

To get set up with a compliant radio in BC will typically cost about $1000 for something like a Kenwood NX1200 plus programming costs. Plus $43/year for the rest of your life. In contrast, you can get a BaoFeng UV-82HP for less than $100 CAD which is a better radio and no additional costs. The truck-mounted version is also a very good choice (BTECH Mini UV-25X4).

When driving on backroads in BC it is essential to have a radio. There are loaded logging trucks coming around tight corners and they will not know you’re there unless you have an appropriate radio and are calling out kilometers. A programmable radio such as a Baofeng will not cause interference of any kind and will allow you to communicate safely for a reasonable price. If you’re the kind of person who loses sleep because they downloaded a movie off a BitTorrent site then you should probably get an ISED radio license and a certified radio. For everyone else, there are great options out there and you can use this useful guide to program your own radio.

It should be noted that there are serious radio laws that are actually enforced. Such as transmitting on police or emergency bands. Don’t ever do that, as a joke or otherwise. It is perfectly legal to listen on those channels but very much illegal to transmit.

Also keep in mind that RR and LADD channels are for professional use and your own safety, not for chit-chat or talking to your buddies. There are thousands of channels and if you have a programmable radio you can set a special channel for you and your buddies while keeping the RR channel open for legitimate use.

Introducing WCP Placer Mining Club

PlacerGold Services March 15, 2016Claims For Sale, gold, gold mining, gold pan, gold panning, mining, placer, placer claim, Similkameen, Tulameen, vancouver 23 Comments

Hey guys, I am pleased to announce that West Coast Placer is starting a mining club. There have been a number of inquiries from people who want to prospect and mine on WCP claims. So we’re starting a club that will provide the opportunity for members to use our claims.

Club members will have access to all of West Coast Placer’s claims. Currently that includes 12 placer claims and two mineral claims in BC. Access to some of my partner’s claims is also available. We have claims all over BC including the Tulameen, Similkameen, Fraser River, Cariboo and Kootenays.

Members will be able to work the claims as if they own them. You can run a sluice, pans or whatever you want. Of course members can keep all the gold that they find.

You will be able to camp on the claims in tents or with an RV (where accessible). Family members are automatically included in your membership. Gold panning is a great activity for the whole family, kids love it. You can bring your friends too, the more the merrier.

There are a few obligations that will have to be met.

The first rule of prospecting club is you do not talk about prospecting club. Just kidding I had to throw that in there.
Members must follow all the regulations regarding placer mining in BC. If you don’t know all the regs don’t worry, information will be provided.
Activities will have to be recorded. This will help with our reports to the MTO. It’s not much work, just keep some notes on the work that you do. Keep track of things like, hours spent working, size and location of holes, and take pictures. This information will also be shared with the group.
If you plan on running a sluice or highbanker you will need to have a Free Miner’s Certificate. If you need help getting one, just ask.

There will be an annual fee of $50. Why a fee? That is required to limit club membership to people who are truly interested. $50 is pretty much free compared to similar clubs. The others are looking for $300 and up. We’re not interested in making money off of memberships.

As a member you will also have the opportunity for instruction in the art of gold prospecting. This is great for novice miners. You can join myself and more experienced members on prospecting trips. That is the best way to learn, you can watch youtube videos and read books all day but nothing beats hands on training.

Members will have support from experienced miners. You can even get help with your own MTO reports for your own personal claims. You can ask advice at any time and we’ll try our best to get back to you as soon as possible.

As a member you will be entitled to a discount on the purchase any of West Coast Placer’s claims. There will be more perks as the club grows.

Update 2021
The club has been active for 5 years, we have a good group of recreational miners. We are still accepting applications for new members.

If you are interested please send an email through the WCP contact form on this link, Contact Form. Explain why you want to join the club and we will consider your application. Not all applications will be approved.

We will not accept applications made through the comments section. See instructions above.

Mining the Ocean Floor with Robots

PlacerGold Drones, Science March 7, 2016aerial imagrey, drone, Ferromanganese Crust, geophysics, gold mining, gold mining equipment, lode gold, magnetometry, mining, ocean, placer, Polymetallic Nodules, SMS, uav, vancouver, Vancouver drone 0 Comment

Mining under Earth’s oceans is just starting to happen. We have gotten pretty good at mining deposits that are accessible by land but 71% of the Earth’s surface is covered by water. To date no large scale mining operation has succeed under the ocean which means that it’s all virgin ground.

Amazingly the human race has spent more time and money exploring outer space than we have under our own oceans. Over 500 people have been to space while only three have ventured to the deepest part of the ocean, the Mariana Trench. We have better maps of the surface of Mars than the bottom of the ocean, although the ocean maps are pretty cool.

The same geological processes that happen on land also take place under the ocean. There are volcanoes, mountain chains, faults and earthquakes. All the same types of mineral deposits occur under the ocean such as epithermal gold, porphyry, and placer. There are also diamond pipes, massive sulphides and everything else that we mine at the surface.

Deposits

The ocean also has types of deposits that we can’t find on land. One special mineral deposit is called Polymetallic Nodules. These are concretions of metallic minerals that occur under the ocean. The nodules grow sort of like stalactites do in a cave, over time layers of metallic minerals precipitate out of seawater and add to the nodule. The growth of nodules is one of the slowest known geological processes taking place at a rate of one centimetre over several million years.

Polymetallic nodules are roughly the size and shape of a potato and contain primarily manganese as well as nickel, copper, cobalt and iron. They can be found on the sea floor or buried in the sediment. Nodules can technically occur anywhere in the ocean but seem to be in greatest abundance on the abyssal planes around 5000m deep. Nodule mining would be similar to placer gold mining except under water.

Anouther resource that is unique to the ocean floor is Ferromanganese Crusts. These are similar to nodules but occur as a coating on other rocks. These crusts can be found all over the ocean with thicknesses ranging from 1mm to 26cm. Ferromanganese crusts typically occur in the vicinity of underwater volcanoes called seamounts or near hydrothermal vents. Crusts with mineral grades that are of economic interest are commonly found at depths between 800m and 2500m.

Ferromanganese crusts are composed primarily of iron and manganese, hence the name. Typical concentrations are about 18% iron and 21% manganese. Cobalt, Nickel and Copper occur in significant quantities as well. Rare earth metals such as Tellurium and Yttrium can be found in metallic crusts at much higher concentrations than can be found on the surface. Tellurium is used in solar panels and is quite valuable.

Sea-floor massive sulphides (SMS) are a younger version of volcanic massive sulphides (VMS). The two deposits are similar except that VMS are typically ancient and SMS are currently forming. SMS deposits occur where superheated hydrothermal fluids are expelled into the ocean. They typically form around black smokers near continental rift zones. SMS are know to hold economic concentrations of Gold, Copper, Silver, Lead, Nickel and Zinc.

Black smokers create SMS deposits by expelling superheated sea water that is rich in metallic elements. Cold sea water is forced through the sea floor by the pressure created from the weight of the water column above it. The water is then heated to temperatures in excess of 600°C when it is brought close to the magma that lies below. The heated water becomes acitic and carries with it a high concentration of metals pulled from the surrounding rocks. Once the hot, metal rich, water comes into contact with cold sea water the metals crystallize and deposit on and around the black smoker.

Mining

Large scale ocean floor mining has not taken off yet. Attempts have been made since the 1960s and 70s but failed due to technological and financial challenges. Small scale shallow ocean mining has been a lot more succesful in recent years. A great example is the popular TV show Bering Sea Gold. The miners in Nome Alaska are using modified suction dredges to comb the sea floor in shallow waters.

Currently proposed sea floor mining ideas are essentially super high-tech placer mining. They involve ways to dig through the surface layers of the ocean floor, bring the material to the surface and ship it to a processing facility. Its a lot like dredging but on a massive scale. As mentioned above, normal hard rock deposits also occur under the ocean but no plans have been proposed to build open pit mines under the ocean. That would involve all the challenges of building a mine on land with the added complexity of operating under the ocean.

Why is ocean floor mining possible now when it wasn’t 20 years ago? The answer comes down to one word, robots. The world of under water mining is the domain of autonomous drones and human controlled ROVs. Robot submarines are nothing new, they have been around since the 70s and have been used to explore depths of the ocean that are very difficult for humans to get to. UUVs or unmanned underwater vehicles are a little bit newer, they are basically an autonomous version of ROVs. Ocean mining robots have just been invented and share a lot of the technology used in these devices and they look like something straight out of science fiction.

The first deep sea mining project is currently being developed off the coast of Papua New Guinea. The project is called Solwara 1 and is being developed by a Vancouver BC mining company called Nautilus Minerals. Solwara 1 is a copper/gold SMS deposit with estimated copper grades of 7% and gold grades in excess of 20g/t and an average gold grade of 6g/t. The property sits at about 1600m depth.

Nautilus has developed a suite of underwater mining robots and a complete system to mine the precious metal and bring it to shore. There will be the bulk cutter pictured above, an auxiliary and a collection machine. Please take a moment and marvel at these amazing achievements of engineering.

After the robots dig up and collect the ore a custom designed Riser and Lift System (RLS) will bring the material to a giant ship that acts as the mine control center dubbed the Production Support Vessel (PSV). The RLS is basically the world’s most powerful suction dredge. It’s pretty complex, this is the description on the Nautilus Minerals website:

The Riser and Lifting System (RALS) is designed to lift the mineralised material to the Production Support Vessel (PSV) using a Subsea Slurry Lift Pump (SSLP) and a vertical riser system. The seawater/rock is delivered into the SSLP at the base of the riser, where it is pumped to the surface via a gravity tensioned riser suspended from the PSV.

Once aboard the Production Support Vessel the mined slurry will be dewatered and stored until anouther ship comes to take the material on shore for processing. The removed sea water is pumped back down the RALS which adds hydraulic power to the system. Pretty cool stuff! Check out the video below for an visual explanation of how it will all work.

Exploration

Ocean floor prospecting is not a good place to be gold panning or hiking around with a rock hammer. It is also difficult to take usable photos due to poor light and lots of debris in the water. So how do you explore for minerals in the ocean? Geophysics and robots.

Geophysical exploration is not unique to the ocean. The same techniques are used routinely on land to find every type of mineral deposit. Ocean geophysics is also not new. The main workhorse of mining exploration is magnetometry. Which means mapping changes in earth’s magnetic field using a specialized sensor. The technique was actually developed to detect enemy submarines during World War II. Since then magnetometers and the science behind them have evolved into accurate tools to measure geology.

I’m using a proton precession magnetometer in the photo below. There is some sample magnetometer data on the left. Mag maps look similar to a thermal image except the colour scale represents magnetic field changes (measured in nanoTesla) instead of temperature.

Magnetometers are excellent tools for ocean mining exploration. They are not affected by the water and are excellent at detecting metallic anomalies. There are now underwater drones that can collect ocean magnetometer surveys without the need for human intervention.

Other geophysical techniques have been used in ocean mineral exploration. Electomagnetics (EM) techniques are also great tools for exploration under water. EM works in a similar way to magnetometry except that they emit their own source. Conventional metal detectors are actually a small version of an EM system. While mag passively measures Earth’s magnetic field EM measures the difference between a source and received pulse. EM also works great for discovering metallic anomalies and is being incorporated into autonomous drones as well.

There are other types of ocean geophysics such as seismic refraction which uses a giant air gun to send a sound wave deep into the crust and measures the response on floating hydrophones. Sonar and other forms of bathymetry can provide detailed maps of the ocean floor. Bathymetry techniques can create imagery similar to LiDAR that is used on land.

Ocean mining is just in its infancy and some really cool technology is being used. Advancements in the robotics have allowed mining and exploration to be completed without a person having into enter the water. As technology advances further we will be able to explore vast areas of the ocean floor and discover immense mineral reserves that are presently unknown. It is estimated that we have only explored about 5% of the ocean floor, who knows what we’ll find down there?

Top Ten Gold Rushes of BC – Part 2

PlacerGold History, Lists November 23, 2015Atlin, Cassiar, ghost town, gold, gold mining, gold rush, Klondike, mother lode, Omineca, placer, Tulameen, vancouver 7 Comments

In part one of the top ten gold rushes of BC we covered the early gold rushes primarily in the Southern regions. As time went on gold hungry adventurers pushed further in the wild North of the Canadian West coast. Their adventurous spirit was rewarded greatly and eventually led them into the Yukon and Alaska.

1865 Big Bend Gold Rush

KootenalMap1897_crop — 1897 Map of the Big Bend Area

The Big Bend refers to the shape of the Columbia River as it makes a huge detour at the continental divide. This region encompasses several different mountain ranges including the Selkirks, the Cariboo Mountains, the Monashees and the Rocky Mountains. In 1865 gold was discovered on French Creek which is straight North of Revelstoke. As in other gold rushes a town was quickly erected named French Creek City. Within the first year the town reached a population of over 4000 people. Nothing is left today but during the rush French Creek had a general store, saloons with cabaret shows, barber shops and of course brothels. Other important towns of the rush were La Porte and Downie Creek. The inhabitants came mostly from the Wild Horse area and other areas in BC.

Steamboats were a major factor during the big bend gold rush. Many of the prospectors reached the area on steamboats via the Arrow Lakes which make up part of the Columbia River. The lake network allowed boat passengers to travel from areas as far South as the US border.

Other notable creeks in the area are Carnes Creek, Downie Creek, McCullough Creek, and the Goldstream River. A 14 ounce nugget was reported to be found on French Creek and numerous smaller nuggets were also found. In 1865 miners were bringing out multiple ounces per day to the man on some claims. On McCullough Creek pay streaks averaged 1/8 of an ounce per yard for many years. Just like other places in the late 1800s hydraulic and drift mining driven by mining companies and syndicates quickly replaced hand mining techniques. The big bend gold rush only lasted two years but mining in the area continues to this day. Several large projects and proposed mines are located in the big bend.

1869 Omineca Gold Rush

The Omineca is a huge region in Nortn-Central BC. The southern boundary is marked today by the Yellowhead highway the North boundary is the Liard Mountains. Gold was first discovered in the Omineca in 1861 but the rush didn’t take place until eight years later. The original discoveries were made on the Finlay River. In the early days there were very few people in the area due to a complete lack of trails, roads or maps and unforgiving terrain and weather. Much of the area is still wild today.

Northern BC circa 1898, red symbols are known gold discoveries

One of the first claims on the Finlay called Toy’s Bar produced 4 ounces to the man each day. Several expeditions were launched though the area searching for gold. One such party, the Peace River Prospecting Party, found a great discovery on Vital Creek in 1869. The creek was named after one of the party members, Vital Laforce who was also instrumental in exploring the Cariboo region. Vital Creek produced nearly 5000 ounces in the years following the rush.

Manson Creek and the Germansen River held the best gold deposits in the Omineca. Gold discoveries were also made on Blackjack Creek, Kildare Creek, Mosquito Creek, Slate Creek and Nugget Gulch. In the early days of the gold rush anything less than an ounce a day was considered unworthy. Many creeks were paying 100 ounces per week. If the gold rush happened today that would be well over $100,000 every week. I’d be finding my way up there any any means possible. Travelling to the Omineca in the 1800s was a feat in itself.

The discovery of gold in the Cassiar in 1873 spelled the end of the Omineca gold rush. As with all gold rushes those who held good ground stayed and kept mining while everyone else headed on to the next boom town. The Omineca is one of the least explored regions in BC today and there are still gold strikes waiting to be found.

1873 Cassiar Gold Rush

Gold was discovered on the Stikine River in 1861 and a minor rush developed. A few hundred prospectors ascended the river in search of gold. There was an existing fur trading fort at the mouth of the river called Fort Stikine which later became Wrangell, Alaska. Not enough gold was found to entice more adventurers to the region but the excitement was enough to prompt Britain into claiming the region as a colony in 1862.

The Cassiar gold rush really took off once the high grade gold deposits in the extreme North of BC were discovered. This part of the country is extremely rugged with huge mountains, glaciers and a very cold winter. The discovery was made in the summer of 1872 by Henry Thibert and Angus McCulloch on a creek that drains into Dease Lake. The creek was named after Thibert who froze to death the following winter. Thibert Creek was very rich, in the first year miners were getting up to three ounces to the pan.

TurnagainNugget — The 52 oz “Turnagain Nugget” from Alice Shea Creek in the Cassiar

In 1874 an even bigger discovery was made further North on Mcdame Creek. The largest gold nugget ever found in BC was taken from Mcdame Creek tipping the scale at 73 ounces! Another giant nugget was found on Alice Shea Creek that weighed 52 ounces.

Several towns sprung up near the gold discoveries such as Laketon, Porter Landing and Centerville. They are all ghost towns now but in the height of the rush thousands of people were passing through the shops and saloons of the Cassiar. Like the Omineca much of this region is just as wild today as it was 150 years ago.

The Cassiar’s rich gold reserves have not been forgotten. There are many large mining projects under way in the region. Due to the high grade mineral deposits the area is known as BC’s “Golden Triange”.

1885 Granite Creek Gold Rush

Granite Creek is a tributary to the Tulameen River. In the gold rush era of the late 1800s the Tulameen was still a remote and wild area. Like many of the best discoveries the Granite Creek gold was found by chance. In this case it was actually found by a cowboy named Johnny Chance. In the summer of 1885 Chance was delivering some horses to New Westminster and took a route through the Tulameen. True to his lazy nature he took a nap at a spot on Granite Creek on a hot day. When he woke up he happened to notice the reflection of some gold nuggets in the water.

Within a year of the discovery the once vacant valley at the mouth of Granite Creek had over 2000 people living there. At the time Granite City was the third largest town in BC. There were over two hundred buildings, 13 of which were saloons. The town never had a school or a mayor though. The bars in Granite ran flat out and never closed down. It was known as one of the wildest towns in the West.

In the early days gold nuggets weighing 5-10 ounces were commonly found. Platinum was also prevalent on the creek. Miners were producing equal weights of platinum and gold. Interestingly for the first few years the Granite Creek miners had no idea what platinum was and most of them threw it back into the creek. At today’s prices gold is going for $1077/oz and platinum is at $870/oz.

The Granite Creek rush brought attention to the surrounding area as well. Other notable creeks in the Tulameen are Slate Creek, Lawless Creek, Lockie Creek and the Tulameen River. Gold and platinum are still being produced today. I heard from a Princeton local that the biggest nuggets to come out of the Tulameen this year were over an ounce. I have some claims on Granite Creek and the Tulameen River myself. Check this post from earlier this year Tulameen Prospecting Trip.

By the end of the 1890s the population of Granite City began to decline. The easy gold was all claimed and in the process of being mined. Those that didn’t already hold good ground headed North to try their luck in the Atlin and Klondike gold rushes that followed.

1898 Atlin Gold Rush

The Atlin gold rush was the last one to take place in BC. It was a direct offshoot of the Klondike gold rush that took the world by storm. The Klondike was the mother of all gold rushes, over 100,000 adventurers poured into Dawson City, YK from all over the world. Some of the adventurous prospectors took a different route and ended up in Atlin.

The first big discovery was on Pine Creek. A town was set up on Pine Creek aptly named Discovery. At it’s peak there were over 10,000 people living in Discovery which was rivalled only by the infamous Dawson City. Discovery had all the excitement of Dawson. There were saloons, brothels, and gambling available at all hours of the day. Discovery is a ghost town today, it was replaced by the town of Atlin.

The gold that was found in the Atlin area was truly legendary. It is estimated that over 1.5 million ounces of placer gold have been produced from the creeks. Some giant nuggets were found too. Several creeks are known to have produced nuggets in excess of 50 ounces! The best placer gold creeks were Pine Creek, Spruce Creek, Ruby Creek, McKee Creek, Birch Creek, Boulder Creek, Otter (Surprise) Creek, and the McDonnel River.

Atlin is a beautiful town, I had the pleasure of working up there a few years ago. In the early 1900s it was nicknamed the “Switzerland of the North” due to the picturesque mountain setting. In many ways Atlin is like Dawson City’s little brother. The music festival is smaller, the gold rush was smaller, less gold was produced but the Klondike is nowhere near as scenic.

Gold mining in Atlin has never stopped. Every time the gold price spikes the area receives another mini gold rush. There are a lot of large hard rock mining prospects in the area as well. The region is not far from the golden triangle and benefits from similar underlying geology. Due to its remote location the area is very under explored and has outstanding potential for exploration.

The BC gold rush period lasted just 50 years. Many of the participants experienced more than one rush in their lifetime. It would have been an amazing time to be a prospector. Here’s a recap of the top ten BC gold rushes:

1851 Haida Gwaii Gold Rush
1858 Fraser River Gold Rush
1858 Rock Creek Gold Rush
1859 Cariboo Gold Rush
1863 Wild Horse River Gold Rush

1864 Leech River Gold Rush
1865 Big Bend Gold Rush
1873 Cassiar Gold Rush
1885 Granite Creek Gold Rush
1898 Atlin Gold Rush

The history of British Columbia is the history of gold and the men who hunt for it. It was the Fraser River gold rush that led to BC becoming a colony and later a province. Our towns, overland trails and roads, and much of the early infrastructure was built to support gold mining activity. Without our lust for precious metal men would not have risked their lives to explore the rugged and unforgiving wilderness of this beautiful province.

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	How to Get Started in Gold Mining
	Search for Slumach’s Lost Gold Mine
	Types of Placer Wash Plants
	Top Ten Gold Rushes of BC
	How to Lose Your Shirt in Placer Mining