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5 Tips to Avoid Losing Gold in a Highbanker

By: Dan Hodgins

Losing gold in a highbanker can be a frustrating experience. After doing all the work to pack in your highbanker and set it up you can still lose gold.

The good news is there many ways to tune your highbanker to minimize gold losses while maximizing capture rate, including the retention of fine flour gold.

The goal is to have complete control over all the variables that can cause gold loss.

Here are five ways to avoid losing gold in a highbanker sluice box.

1. Moderate Water Flow

Using the right amount of water flow is one of the most crucial ways to capture the most gold possible. Use too little water, and your riffles will pack solid with heavy minerals such as magnetite or hematite. This can cause gold to skip over the top and out of your highbanker sluice box. Use too much water, and gold will not have enough time to settle in the riffles or matting, and it can exit the sluice box. This can lead to heavy gold losses.

With the correct flow (moderate), water will go down the sluice box in a flat, controlled manner with as few bubbles as possible. What you want is something called laminar flow which is flow that looks as close to a sheet of glass as possible. Although emulating this 100% isn't realistic, we can still try to emulate perfect flow as closely as possible.

2. Moderate Angle

Closely related to water flow is sluice box angle. A steeper sluice box angle will cause faster water flow and a greater scouring action in the matting and or riffles. Knowing how to set the right angle for a sluice box is important for capturing the most gold possible.

With too steep of an angle, the water will be moving too quickly and gold will not have a chance to settle. If the angle isn't steep enough you can get sandbars forming on the matting or riffles and this prevents gold from sinking down to the bottom out of the flow. Any gold that is not stopped by the friction in the sluice box can skip right on out the end. The right sluice box angle, combined with the right water flow, will form an ideal exchange action in the matting.

But these are not the only two variables in the gold capture equation in a highbanker. There's another factor that relates to material.

3. Moderate Feed Rate

An adequate feed rate for a highbanker sluice box is neither too much, nor too little material in a given time period. It can be easy to overload a highbanker if you feed it too fast. This can lead to too much viscosity in the slurry which can prevent gold from sinking down into the capture medium such as matting, riffles, or carpet.

The right feed rate is usually pretty easy to determine. You want clean rocks exiting the back of the sluice over the grizzly bars. If you overfeed the highbanker hopper, in some cases you can get a pile up of rocks over the grizzly. You want to keep the grizzly screen free and clear so that all gold will go downward into the sluice.

It's OK if the water in your highbanker sluice is a chocolate brown or gray color, this is normal when using a highbanker. For a smaller backpack highbanker (e.g. 6 inch), you won't be able to feed it as fast as you would a bigger machine such as an 8, 10, or 12 inch highbanker. But with a well-designed system such as the Crux Gold Trek 6 inch highbanker you can feed it at production speed (for that machine).

4. Adequate Material Washing

The right amount of wash time in the highbanker hopper or header box depends on how dirty the material is. The more clay and/or mud, the longer and more vigorously you'll need to wash the material. If you're working in an area with minimal clay and little black sand, Less wash time is OK.

A good rule of thumb is that your rocks and cobbles should come out very clean, ideally with no mud or clay attached. Similar to a highbanker sluice box angle, The angle of your hopper or header box will determine how fast cobbles and rocks tumble out the back.

In an area with a lot of clay or mud you may wish to reduce the angle of the highbanker hopper box to enable a more comprehensive washing. This will reduce the chance of losing Gold that is attached to bigger rocks and cobbles in the form of clay.

5. Highbanker Hopper Capture

For those of you who are concerned about a highbanker sluice box losing fine flour gold, you may wish to consider adding hopper capture to your highbanker set up. What this looks like in practice is adding expanded metal (e.g. 3/4 inch or 1/2 inch) over miner's moss and V matting in the highbanker hopper.

This allows the light sands and minerals to blow out quickly while the heavy minerals move more slowly. Some of the gold will be caught in this capture medium in the header box -- often a surprising amount.

Having some capture matting in the header box gives the bottom sluice time to clear out, thus freeing up space In the riffles or matting for gold to be captured. Highbanker header capture can work with many different types of highbankers. If your machine is not built with a capture system in the header box, you can always add your own afterward.

Some of the different capture media we have heard gold prospectors using include: expanded metal over miner's moss, expanded metal over ribbed carpet, and expanded metal over rooftop conveyor belt a.k.a. gold cube matting.

Bonus: Correct Classification

It's important to classify your gravels down to the size of the gold in the area. If you are in an area that only has fine flour gold you can easily use 1/4 inch classification on your grizzly screen. In areas with gold nuggets you would want to use 1/2 inch or 3/8 inch grizzly bars on your highbanker.

The overall idea is to classify down as small as possible without clogging up the grizzly bars (or screen).

Summary

In summary, the best way to increase gold capture in a highbanker hopper and sluice box is to use a moderate feed rate combined with moderate water flow and angle. This allows the gravel and sand caught in the riffles, expanded metal, drop riffles or matting to be 'dancing'.

If you are concerned about heavy fine gold losses in your highbanker sluice box, you can always add a capture pan or capture tub at the end of your sluice to check for losses. In my experience, any of the popular commercial brands of highbanker will have excellent gold capture in nearly all types of material with moderate feed, angle, and water flow.

A good rule of thumb is your sluice should not look like a white water torrent. It should be a controlled flow, as flat as possible, with as little turbulence as possible, with as few bubbles as possible. If you notice excessive bubbles then add a damper flap like Freddy Dodge from Freddy Dodge's Mine Rescue uses. to help struggling commercial placer miners improve their fine flour gold capture.

A very high gold capture rate is possible using gravity concentration methods such as a highbanker sluice box. The key is to know which material feed rate, sluice angle and water flow is best for your equipment.

That is the secret to capturing as much gold as possible while avoiding losses.