How to Set Up and Operate a Sluice Box or Highbanker
Now we are only looking at prospecting and handmining applications, where you will be hand shovelling materials into a sluicing system, I’m going to recommend that you look into using a highbanker setup, or a power sluice, you can buy a readymade one or build one yourself, either way it is important that you understand how they work and how to effectively operate a sluice box recovery system
The first thing that is to be considered is that for a sluice box to separate, and classify gravels for gold recovery is that you will want some type of pre-screening of the alluvial materials. The reason for pre-screening your gravels is that the there isn’t much point in washing the larger gravels through your sluice box, as they are not gold. There is very little gold over ¼ inch in size, through there may be and this is a good reason for checking the materials that are oversize as there just might be a nugget or two in the oversize.
Pre-screening can be accomplished in a couple of ways, one is to have a hand held screening device and put a shovel full of gravels in and shake it back and forth until you have reduced the gravels down to ¼ minus and then take that material and run through the sluice box. This does work, but is very labour intensive and slow. The highbanker set up has a pre-screening device attached, this device is called a grizzly and can changed from a 1/8 inch openings to ½ inch openings, you don’t want to have anything larger than these sizes running through the sluice box as the large materials can and will lodge in the riffles and cause the water flow to scour the concentrates in the riffles and wash the concentrates out of the sluice box.
Okay now after the gravel/clay materials have been through some type of classification we run them through the sluice box, with the proper amount of water flow, feed rates, pitch, and riffle design it is possible to recover 90-95 percent of the gold that is contained in the materials that you are processing. So what I have found that works for the handmining, is to use only a couple of designs, 8-10-12 inch wide sluice systems with a 1.5 in 12 inch pitch running 30-45-60 gallons per minute respective to size of sluice width, with ½ inch angle iron riffles spaced at 1 ½ inch apart for the first 12 inches of the sluice box and for the last 24 inches of the sluice box use ½ inch high by 3 inch open expanded metal riffles. This will catch any larger pieces of gold in the first foot of sluice and any of the fine gold will be caught in the following expanded metal riffles.
Underneath the riffles configurations I like to use a porous carpet material that is normally used as a pot and pan scrubber, it’s available through local home stores in packages that are 8x6 or up to 6x12 inches and 8 or 10 to a pack, these you will either fit into the sluice box individually or you can glue them together into a sheet that runs the length of your sluice box. This material is cheaper and in my opinion traps fine gold better than expensive miner’s moss, $4 to $5 dollar for 12”x 36” for scrubber pads $35 to $45 for miner’s moss. But in a pinch even a piece of indoor/outdoor carpet or a towel type material will work fairly well, as long as it is able to make a good base for the riffle set up to seal on, reducing any scouring of your fine concentrates out of the riffles.
Cleaning up the sluice box and the riffles, this is where we see if the ground and materials that you are working is any good or not, it is important when prospect testing to do reliable controlled amounts of sampling, measured amounts of materials versus measured amounts of gold and other economic minerals recovered, this enable you to properly evaluate the property for the purposes of handmining and possible development into a working mine at some later date. So now at the cleanup stage we will want to be very careful in removing the riffles and concentrates from the sluice box in order to get an accurate reading and measurements of the,
(A) amount of gold per yard, (B) Sizes of gold types in materials, (C) where in the gravel deposits the gold is coming from, as in possible paystreaks.
With this in mind if you have a two piece riffle system, which I do recommend, (A) take them out and rinse off in tub then (B) take the front carpet out and wash it out in tub, (C) take the back carpet out and wash that out in a different container, this is to keep the heavy larger concentrates separate from the little smaller concentrates. Take the concentrates in the first tub and first classify it down to ¼ inch materials, carefully check the oversize material and anything that appears to have any values (gold, silver, platinum, and gemstones) save and place in sealed container, pan the concentrates down using your tub for dumping the tailings. Once satisfied with the results or the first part of the cleanup store the finished concentrates into a sealable container and continue with the concentrates from the tail end of the sluice box, once you have went through these concentrates you will have a fairly good idea as to what type of gold you have as far as size, coarseness, values of gold oz per yard of materials.
There is a very good reason for this, and I will explain that here, knowing what the size of your gold is in the alluvial deposit allows you to set up a wash plant system tailor made to recover that specific size and type of gold making your operation that much more effective and labour, cost efficient. So depending on the size of gold recovered you may want to have larger grizzly opening and run higher volumes of water if the gold is nugget size with very little fines involved, or if the gold is mainly fines run smaller grizzly openings and less water to make recovery of the fines more effective. Testing the gravels with a methodical sampling program in mind and recording your results will, with practice and trial and error give you the information needed to properly evaluate your prospect and claim and most importantly set up the right type of wash plant gold recovery system.
Hopefully this will be of some use to you all looking to cash in on fine gold recovery methods........Greywolf