WORKING DELTA MINERAL
CONCENTRATING MILL
These pictures show a three level plant, where the raw ore is delivered by dump truck to the top level and dumped over a grizzley to separate the largest stones from the balance of the ore. Sometimes it is advisable to re run this oversize in a separate trommel washer to liberate any mineral particles remaining on each oversize stone. Usually this is a secondary trommel wash unit, so as to not damage the screens in the main wash/screen trommel unit.
The hopper contents are discharged onto a conveyor and delivered into the end of the trommel washer/screen unit. The material is washed using liberal amounts of water and the lifters installed inside the trommel tube lift and mix the ore as it passes through the tube. As the ore moves through the wash section the ore is washed from the stones. Screening is accomplished at the opposite end of the unit.
A predetermined final size screen (one that will allow the majority of ore nuggets to pass through) is selected. The screen shown was designed to produce three sizes of stone plus the final screened ore size. The screened oversize rock was used for mine road construction and sold to others as washed screened stone. An added revenue factor.
The screened ore falls from the underside of the washer/screen into a hopper and is delivered to the jig mill via a chute. The wash water first introduced into the trommel is also used as top water for the rougher jig (the first jig). Sometimes too much trommel water is generated, depending upon the difficulty of the ore separation. If this is the case, just above the screened ore chute is shown an auger de-watering unit. Using this enables the reduction of top water to the jigs. A de-watering device is usually not required as long as a large enough rougher jig is installed as the primary jig in the jig mill. (See first picture.)
As the washed and screened material is introduced into the jig mill the rougher jig is shown below. This jig is a "Pan American" style jig using bottom diaphrams for bed action.
The hutch product of the rougher jig is run through a second jig to further concentrate the ore. This jig shown, uses side plunger for jig bed action.
A third jig can be used for further concentration. Use of subsequent jigs for further concentration is determined by the value of each jig's concentrate. Sometimes the recovered black sands carry values other than precious metals and have a market of their own. This determines where one stops concentrating and discharging as waste the jig hutch product. You will note that it was determined that a third concentration would not be economical, so the discharge from the second jig hutch is diverted to the outside of the jig mill. The third jig uses side diaphrams for jig bed action.
All three jig units are permanently wired, plummed and installed in three levels within the portable building. Gravity and water are used to move the hutch concentrate from jig to jig. The jig top tailings from each unit is discharged outside of the mill building and hauled away.
Shown below are barrels of hutch concentrate, ready for final precious metal separation.
The jig mill can be constructed as a trailer unit, so as to be easily moved from one ore body to another. One two or three duplex jigs can be incorporated within the building.
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Shown in the above views:
Entrance door, Secondary jig waste discharge (above window and to the left), Third jig waste discharge (door side)
Second Picture: Trailer axle, frame and rougher jig ore introduction. (top left).
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