Wednesday, August 20, 2008

How to Run a Sluice Box: Part II

How to Run a Sluice Box: (Part 2)

In my previous post on this subject, I walked you through the first three steps of the process: setting up the box, starting up, and minding the store. Now I'll cover the two remaining steps of the process, cleaning up and panning your concentrates.

4) Cleaning Up

Although there is some debate on the subject in recreational placer mining circles, there is no definite time or stopping point in terms of exactly when a sluice box clean up should be performed. Some miners prefer to clean up on a regular basis such as every couple of hours while others will run material through a box for half or day or longer before they perform a clean up. Basically, it's a judgment call on your part.

Just the same, here are a few guidelines for when to clean up:

When the riffles start packing up with black sand. If you see the sluice box riffles packing up near their tops with heavy black sands, it's time to clean up. By continuing to run the box in this condition you risk losing gold since the smaller or lighter pieces will be washed down the box and out the lower end.

When you can easily see decent amounts of visible gold sitting in the box. If you find yourself in this situation, lucky you! This means you're running good material through the sluice box and are getting the gold. Typically, the heavier pieces of gold such as small nuggets and coarser pieces and larger flakes (what some miners call "pickers)" will remain in the upper reaches of the box near the "feeder" head or the first two riffles.

A word of CAUTION here though: it's usually not a good idea to recover these pieces by hand with a strong water flow running through the box. If you do, make absolutely certain you can recover that flake or nugget without dropping it and remember to keep a gold pan underneath as you make the recovery attempt. (I've seen good gold lost this way a number of times and I myself lost a nice small nugget this way last year on the North Yuba River in California. I'm still kicking myself in the rear over that bonehead move...)

When you don't see any visible gold in the sluice box. As I stated in the previous post on sluicing, this is definitely not a good sign. If you've been running shovelfuls or bucketfuls of gravel through the box for a reasonable amount of time and don't see the gleam of gold winking bank at you, you may want to reassess. One way to do this is to perform a clean up and determine what's what. Either the gold is too small to see well or in the worst-case scenario, your gold-bearing material doesn't have much gold in it.

OK, now you've decided to perform a clean up of your sluice box:

Gently lift
the sluice box from the current keeping it as level as possible while you do so.
Bring it to the bank and set it down carefully.
Now you can remove any nuggets or large flakes or pieces of gold sitting in the box. (Leave the smaller pieces alone.)
Get a 5-gallon bucket or, in a pinch, a gold pan.
Set the lower end of the sluice box into the bucket or gold pan.
Raise the box to a slight downward angle by propping it on a small log, large flat rock, or other reasonably stable surface.
Remove or lift the riffle array and the expanded metal screen from the miner's matting on the bottom of the box. Set these items aside.
Roll up the matting starting from the upper end of the sluice box and place it in the bucket or pan.
Use another gold pan or bucket to slowly pour water down the angled box and wash the smaller pieces of gold, black sands, and dirt that were trapped under the matting into your 5-gallon bucket or pan.
Fill your bucket or pan with water and scrub or wash out the miner's matting thoroughly. Once it's cleaned, set it aside as well.

Your bucket or pan is now filled with heavy black sands, gold, and perhaps odd items like bits and pieces of lead, rusty nails, or oxidized conglomerates. These are called "concentrates."

Panning Concentrates

In order to recover the gold you trapped during your sluice box runs, you'll need to pan out the concentrates in your bucket or pan. This should be a very methodical panning operation where you employ maximum skill and patience, so don't be in a hurry. Take your time. Some placer miners use a smaller gold pan called a "finishing" pan to work concentrates, but I prefer the standard 14" diameter Garrett "Gravity Trap" gold pan.
Next, start panning down (sorry, but if you can't pan well you shouldn't be running a box in the first place) your concentrates until the larger pieces or flecks of gold are visible and then work as much of those aside as you can and recover them using a "snuffer" bottle, model paintbrush, tweezers, or a moistened finger. Whatever works best for you. Any flour or flood gold in your concentrates can be saved for a later date and more efficient recovery using a mini-sluice, "blue bowl" concentrator, or a spiral gold wheel.
Place your recovered gold into a high-impact nalgene (or similar dense plastic) vial for safekeeping. DO NOT USE the glass vials commonly sold by prospecting supply shops unless you get a kick out of seeing all your hard work go "bye-bye" when you drop that vial with your "goods" in it. And, eventually, you will. I refuse to use glass vials out in the field, anytime, anywhere. (Trust me.....I can tell you a few horror stories about using glass vials to hold your gold.)
That's essentially it my friend. Though the written steps may seem like a lot to go through, running a sluice box is about as easy as it gets in terms of using placer gold mining equipment. Actually, running a box can be a lot of fun and it's a real kick when you can see the gold glimmering in the box under the sunlight.
So go for it!
(c)  Jim Rocha (J.R.)  2008

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