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Monday, March 7, 2011

Prospecting equipment -- the sluice box

          The sluice box is the next step above a gold pan for recovery of larger quantities of gold.

          We’re not going to get into sluice box set-up extensively because there are so many variables involved.  What we will address are the various features offered in sluice boxes and what we see as positive and negative features of each.

          First of all, the sluice box is only as good as its operator.  Here’s where set-up and technique play a huge role. 

You have to have sufficient water to wash material, but too much water is worse than too little.  The most common mistake we see is too steep a gradient with a large water flow.  Time and again we’ve seen “a worthless sluice box” tossed aside while our sluice is used in the same location, adjusted to allow a sufficient flow of water to eddy over the riffles.

We have a 10-in. x 4-ft. sluice box from Keene Engineering that we use often.  The positive features of this box are heavy-gauge steel that can handle large flows of water with a riffle design to optimize recovery in this scenario. 

We interject here to refer back to the sieve and a 5-gallon bucket.  A little time spent “screening” the large rocks out of your material is the best bet to maximizing production with a sluice box.  You hopefully know the size of gold contained in the area and can use a sieve sized to maximize production and minimize quantity of material.

That scenario is not a good one for wet material, which we’ll be dealing with in the early spring.  We have gone so far as to fill a bucket with water, insert sieve and wash wet material.  That option is a good one for material containing a good quantity of “pay dirt”, but is also a dirty and tiring task.

Our means of determining whether we’re throwing out gold with rocks is to pan several test pans of oversized material and see what we see! 

That principle goes for the tailings coming off the sluce box also.  We often run a test pan of material at the point of discharge from the sluice.  If you see gold there, STOP!  Your angle is too steep or you have too much water running through the sluice, or both!  You can salvage some of that lost gold by resetting the sluice and re-running the tailings.  We’ve jokingly told many fellow prospectors to let us know where they sluiced so we can return and recover everything they lost in the tailings!

Back to sluice boxes… we have an aluminum sluice box the same size as the Kenne which we bought in Rapid City many years ago.  The features we like about it are lightweight and easy clean-up and assembly compared to the Kenne.    

We are huge fans of the black ribbed matting sold in rolls and cut to fit the individual sluice.  The deep-V matting is our preference, and Bob cut it to fit the sluice box flare and tuck under the first riffle. 

We did not permanently attach it to the flare and there’s a valid reason for that.  Throughout a day of sluicing, we do not clean the sluice box until the end of day.  What we do is pull the box out of the flow of water, remove the black ribbed matting and clean it!  We estimate about 80 percent of the recoverable gold is in the matting. Cleaning the matting can be a gold-saving step… if you run into some clay-bound material you won’t lose much if you’ve taken a minute to clean the ribbed matting!

          A friend highly recommends miner’s moss, which we have used and find effective.  We use the black ribbed matting for our own selfish reason… we like to see the gold!

We see a need for a smaller, more portable, what we will term a “prospecting” sluice box.  We’ll mention this to our favorite fabricator, Jim, and see what he can produce!  Ideally, this sluice box would be approximately 6-inch by 2-feet with a flare and black-ribbed matting cut to fit.  Our focus is to maximize the most common Black Hills scenario of small, shallow gulches.  Our tests have shown that with proper set-up, they is little call for more than about 3 riffles.

Let us know, through comments, what sluice box or pan you use and positive, negative features!

We also encourage pro-recreational and any legitimate pro-mining comments about the Black Hills region.  The U.S. Forest Service, Department of Environment and Natural Resources, Bureau of Land Management all need to hear our voice when contemplating legislation regarding mining.  Support mining with your comments! 

1 comment:

  1. Where do i buy the sleuce in South Dakota?, 605-251-4647, Marc