The Miller Table: Refining Fine Placer Gold
Recreational gold prospecting can be a rewarding hobby. There is always the possibility of a rich pocket being found, but the hobby also involves some tedious labor. There is the digging and then the cleanup of concentrates. Fortunately, there is a simple technology dating from the 1800s, called the Miller Table, which effectively separates fine gold with a minimum of fuss.
To fulfill a dream, to be allowed to sweat over lonely labor, to be given a chance to create, is the meat and potatoes of life. The money is the gravy.— Bette Davis
The last phase of the clean up is not only monotonous, but frustrating. Very small particles of gold, the stuff of gold dust, are so tiny that separating them from black sand requires a very adroit hand when panning. A very slow washing of pay dirt in a pan can easily push oat gold away. For this gold, there is another tool that can save a prospector hours of labor. It is a remarkable sluice.
The Miller Table is a sluice with no riffles designed to take advantage of two forces: the force of gravity and the force of running water running at no more tilt than about 5 degrees. The table itself is flat made of smooth or nearly smooth material. Some prospectors like to build them out of material that has small irregularities likening them to fingers (low pressure zones). Material like slate, Easy Liner Mat, Hobbico Mat, melamine, plastic cutting boards, Formica counter tops, and plywood will work and are commonly used. When using materials that have a wood or pressed board structure you will need to seal the material very well for water proofing. I have seen folks sand the plywood and apply from 3 to seven coats of spar urethane, lacquer, or spray paint (Rust-oleum and Krylon seem to be preferred).
Free Plans and Explanation of the Miller Table
Aluminum or wood usually make up the framework. At the head of the sluice is a piece of copper or PVC tubing with holes allowing water to gently spray out onto the table. To this piece is connected a fitting to accommodate a garden hose or tubing from a submersible pump. An adjustable foot at the water end of the table allows for achieving the proper elevation at one end, usually no more than 5 degrees. All of the connections between wood and aluminum pieces must be sealed with a good quality waterproof sealant like Loctite Clear Silicone Waterproof Sealant.
When the water is coursing down the table it resembles a sheet of old glass. The water flowing from the high end of the table is adjusted in such a way that the force of the water stream will not overcome the force of gravity on the gold. That water flow must be fast enough to wash away the black sand that fine gold is most often found in (magnetite and hematite, oxides of iron). When the water is adjusted just right, a plume of material will fan out down the table with the yellow gold powder collecting higher. Over time the black sand will eventually run off the end. If you are sure there is no gold within the black sand, you can speed the process up by using a bristle brush to whisk it away. The gold can be collected with a snuffer bottle. You can use a bristle brush to move the gold to a central place on the table for collection. Tapping the end of the table gently can move the black sand down the table slightly if desired.
Three Specks of Gold
To Scoop or Spoon?
A scoop or tablespoon lets you sprinkle the fines at the head of the table. Some people prefer a scoop for better control when dropping the concentrate. Most Miller tables require material to be 20 mesh or smaller. There are 20 mesh commercial classifiers that can be purchased online, or you can buy screen at a hardware store and build your own. The important thing to remember is that the concentrates you collected after panning must be screened again before using the water table.
For those of you who enjoy outdoor recreation, gold prospecting may be for you. It is a great family activity right for folks of all ages. I haven't gotten rich from recreational prospecting, but it gives me good exercise, sharpens my mind, and gives me the opportunity to enjoy Arizona's placer gold. Bring your pay dirt home and screen it with 20 mesh, then give a Miller Table a try after you have panned all the gold you can see.
Miller Table Tips, March 20, 2014, Gold Refining Forum.com, retrieved 8/6/2018
Rocky Mountain Prospector, May 6, 2018, Miller Tables for the Win-Fine Gold Recovery Methods, retrieved 8/5/2018
Nevada Outback-Gems.com, No Date, http://nevada-outback-gems.com/Reference_pages/black_sands.htm, retrieved 8/4/2018
Black sand, June 20, 2018, Placer Deposits, retrieved on 8/5/2018
SCRIBD, Gary Weishaupt, 2018, How to Build and Operate a Miller Table, retrieved 8/6/2018
Questions & Answers
© 2018 John R Wilsdon