78 Transactions Tennessee Academy of Science. 



final settling- and the water drained off by pulling the gates down 

 to the top of the mass of sand. The sand is then washed out by 

 a hydraulic nozzle into another tank, from which it is lifted a sec- 

 ond time by a pump to a tank corresponding to the first used. 

 This operation being repeated four or five times, practically all the 

 clay is removed from the phosphate-sand, and the product is 

 finally carried to a very much larger settling tank, where it is al- 

 lowed to stand for forty-eight hours, in order that the water may 

 drain off. The lump, having been cleaned as first mentioned 

 above, goes along with the sand to rotary driers, where it is dried 

 down to not over 2 per cent moisture. It is further to be noted 

 that the water which passes over the gates of the tanks during the 

 process of filling is conducted along settling troughs with bottoms 

 inclined to a central hopper, where the finest material is caught 

 and utilized. It is claimed that the special advantage of this ma- 

 terial is that no additional finestuff is made, as is the case when 

 lump rock is passed through log washers. 



Plant No. 2, one of the most recently installed in the field, uses 

 hydraulic giants for mining. These guns, as they are called, wash 

 the rock into a sump located as close as possible to the center of 

 the area being mined. This particular deposit has very little lump 

 rock, 85 per cent of the material being phosphate sand. When 

 the material has been washed into the sump by the guns, eight 

 inch centrifugal pumps take up the slush and carry it to a plant 

 about a quarter of a mile away. Here the stream is discharged 

 into a double log washer, of which there are two sets in tandem. 

 These discharge into wash trommels, where the lump and sand 

 are separated. The lump goes to a picker belt for the removal of 

 the clay, and thence to the wet storage pile. The dirty overflow 

 water from the logs goes to a settling tank, which also receives 

 the sand from the wash trommels, and these wash trommels, as 

 will ])e noted, act also as sizing screens. The settling tank is a 

 box 15 by 30 feet in plan, the bottom consisting of forty-eight 

 l)yrami(lical boxes, into which water is fed from below, the prin- 

 ci])lc being ibat of the whole-current l)ox-classifier. 1'lie settling 

 tank discharges into four ril'lle trough launders, in which run tiight 

 conveyors. These launders have a slight u])war{l incline at the dis- 

 charge end. Hie sand travels witli llie Highls against the current 

 of water, 'idiey discharge into cul)ical boxes, five feet on the side, 



