Gold Plant OPERATION INSTRUCTIONS

One of the most important things to put in effect in a placer operation like the one described, is to never allow the water to go over the rag plant when the feed has been shut off. The water, by itself, with no placer material going over the ragplant, will wash much of the free gold off and it will be lost.

When starting up the operation, the same thing must be in effect. Start the feed and water at the same time so that the gold on the carpets will be protected by the placer material in the water.

The carpets must be clean and the nap on the carpets not covered, so that the free gold can be caught in the nap and the finer gold go into the carpets.

In other words, when we say the carpets must be "clean", we mean you can not let the sand and iron build up on the carpet (like a sand bar).

With the right amount of feed, the right amount of water, and the correct pitch, or slope, on the rag plant, all of the sand and iron will be moving down the rag plant and the gold will be caught in the carpet (with a small amount of iron) when the carpets are cleaned.

All of the above must be done in the field, on a trial and error basis, until all three conditions are right.

A starting point could be 1/4" slope to each foot on the rag plant; then adjust up or down until the best condition is found. Water and feed are set the same way until best results are obtained. Once these results are obtained, a good, smooth operation can be maintained.

Fig. 1 (Feed Bin) should be large enough to assure a constant and even feed to the screen with enough cushion so that at least a half bin is maintained between truck loads (or however placer material is handled) from pit to feed bin.

Fig. 2 (feeder) There are several types of feeders that can be used the most common being a conveyor belt type with a gear-head motor to move belt very slowly so that the feed is fairly deep on the belt. An adjustable steel gate on the bin at feeder helps adjust to an even feed.

It is very important that an even and constant feed be main¬tained so that the right amount of water can be held at a steady rate. Also when the right amount of feed, plus the right amount of water is maintained, the exact pitch (or slope) of the rag plant can be set.

With all THREE of these conditions in control, the gold should settle in the carpet or the rag plant, and the sand and almost all of the black iron will go to tail and be eliminated.

Fig. 3 (Screen) A trommel or a vibrating screen can be used for classifying the material to go over the rag plant. Where there is quite a bit of large pebbles, a trommel screen is better, for it is more rugged and will stand up better. With finer material, a vibrating screen can be used.

On most placers with fine gold, a 1/4i" or 3/6” mesh screen is generally used. The fines will go to the rag plant and the over-size will come over the discharge end of the screen into a by-pass chute to waste.
The oversize material must be handled, so the screen should be elevated so that a stock-pile can accumulate and be moved with a loader, dozer or a conveyor belt.

Fig.4 (Rag plant) This is a sluice box, 4to6ft. wide and 35 to 40 ft. long. It has indoor-outdoor carpet in the bottom of the sluice with riffles on top of the carpet to catch and save the fine gold.

Several types of riffles can be used; punched plate, 3'X3'X3/16" with 11/4”X11/4”' square openings punched out, works very well. Riffles made of 3/8" rebar welded into 3' by 3' sections, with l"- 1 1/2" spacings can be used. There are also several other types of riffles which can be used.

It is very important that the riffle plates fit tight against the carpet. This is done by using 1/2" machine bolts sticking up about 3 1/2" and coming through the bottom side of the sluice box. Bolts are welded into place with head of bolt on the under side sluice box. Nuts are screwed on to bolt, and tie-down tightened to keep riffles from moving and held tight against carpet. Wedges can be used between nut and tie-down to hold tie-down against riffles.

Tie-down plates are flat steel plates l/4" X 3" X 12'- long. They are slotted to slip over bolt on top of riffle plate, and are tightened by screwing down nut on bolt, or by driving wedgw tight between nut and tie-down plate. (Shown in sketches on bolt and wedge set up.)