Fine Gold Recovery Can Be Problematic
Fine gold recovery often proves problematic for most small-scale or recreational gold miners. Even the best gold panners experience difficulties separating those micron-sized specks of flour gold from black sand concentrates, and this can, over the long haul, reduce gold recovery rates and increase frustration levels.
Luckily, there are numerous methods for circumventing these recovery issues and the mini-sluice is one of those methods. The mini-sluice box is simply a scaled-down or greatly reduced version of its larger cousin and operates much in the same fashion, albeit with much less water flow and greatly reduced material feed required.
"Grizzly's" Mini-Sluice Box
"Grizzly" is from Alberta, Canada and he has come up with a simple but effective version of a recycled flow mini-sluice that can be easily constructed at a very reasonable cost. Here Grizzly describes his "do-it-yourself" (DIY) mini in his own words:
"The Sluice Needs to be About 3 Feet Long"
"Basically, the sluice needs to be about 3 feet long. (Mine is 42" because that's the length of aluminum I had at the time.) "
"The legs are two 1/2-inch square pieces of aluminum glass frame I scrounged at a scrap metal dealers junk pile. I drilled them and attached them to the hopper so they can fold up against the bottom of the sluice for carrying. I put a cross brace between them from a scrap of aluminum about 1/3 the way down the legs. You could put a chain from the bottom of the sluice to the legs to prevent them from collapsing but I haven't done that."
"The Switchboard Matting Carries a Slight Negative Charge"
"The way it works now is that one end is supported by the 5 gal pail and the other is supported by the legs and is adjusted for slope depending on the fineness of the concentrates. The concentrates should be screened to minus 12 mesh."
"I like this unit because the switchboard matting carries a slight negative charge in the rubber which helps the gold particles drop against it. This unit is ideal in areas where water is scarce because the water is recirculating in a closed system and you can pull up a stump and sit right down to work. I often put a small plastic margarine container on the end of the sluice and catch the tailings for a second pass before I toss them."
"You Can Power the Sluice for About 2 Hours"
"I was thinking about building an auto feeder to dump 15-20 pounds of concentrates into my mini but I don't like carrying the extra weight to the places I end up in."
"You can power the sluice for about 2 hours 'off road' with a motorcycle battery (smaller than the car type). You will need at least a 500 gallon-per-hour pump. A submersible pump would work OK too."
As you can see, Grizzly's version of the mini-sluice is very well thought out and constructed, and it holds great potential for recovering extremely fine gold. However, there are many other versions out there (including non-motorized models) that might give Grizzly's mini a run for its money.
(c) Jim Rocha (J.R.) 2008