Gold concentrating equipment

The equipment needed at the concentrating area include a grizzle to remove large rocks from the placer material, a screen to screen the material to the size which will be put over the sluice, and the sluice box or rag plant. The most economical way to install this equipment is to have a gravity feed between each piece of equipment. The material which goes through the grizzle drops by its own gravity on to the screen intake and the screened material drops on to the sluice box by its own gravity. One disadvantage of having only gravity feed is that the unit may be too high to move easily. Conveyors are used to move the material where gravity feed is not used. These conveyors are also used to control the amount of material which is being fed to the screen and sluice. Conveyors and elevators may be needed, but their use should be carefully planned so they are not used needlessly.

If many large rocks are present in the placer material a grizzle will be needed. A grizzle is a row of heavy steel bars which screen out the very coarse rocks. Used mine rails turned upside down and welded to a heavy frame at each end makes a good grizzle. The finer material falls through the spaces between the bars and into a hopper below. The rocks which do not pass through the grizzle are shoved off to the side. The spacing of the bars will depend on the size of the screen which is used ahead of the sluice. This space is usually three to four inches.

The material in the hopper is fed directly into the screen or carried by a conveyor to the screen. The discharge rate of the hopper or the amount of material carried by the conveyor belt are controlled to give the correct amount of feed to the sluice box.