Gold Riffles

Riffles are used on the flat bottom of the sluice to cause turbulences in the water, which drop the gold particles, and trap these particles once they are dropped. As mentioned earlier, steel punchplate riffling with indoor-outdoor carpet under it works well on fine gold (10 mesh and less). If coarser gold is present, additional riffling may have to be added to ensure that it is saved. Again, this is a case of trial and error, so make your riffling so it is easy to install and remove. If the sluice will save the coarse gold or the fine gold but not both, it may be necessary to use two sluice boxes. The first will have more severe riffling and will be adjusted to save the coarse gold. The tails from the first sluice will then be rescreened to a smaller size and put over the second sluice. This sluice will have a flatter pitch and be adjusted to save the fine gold.

The concentrate made on the sluice box is not a clean concentrate. It should contain all of the gold, but also black iron and small amounts of sand. If the placer operation is large enough to justify it, a clean up mill, as described earlier, may be built. Smaller operations may want to send their concentrates out to a mill to be cleaned. The mill will make pure placer gold, or sponge buttons, or gold bullion from the concentrates. The pure placer gold can be sold to anyone, the bullion and sponge buttons can be sold to the smelter. If you want to process your gold into bullion or sponge buttons yourself, a concentrating table, amalgamator, retort, and melting furnace will be needed. The concentrates from the table are put into the amalgamator and amalgamated, retorted and melted, as described earlier. If bullion is to be made a gold melting license is required. No license is required to make sponge buttons as long as one does not have more than 200 troy ounces of gold in sponge button form at any one time.