GB612075A - Improvements in and relating to the washing of minerals and ores - Google Patents

Abstract

612,075. Washing granular materials. RATCLIFFE, A., TALBOT, G. W., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. June 27, 1946, No. 19252. [Class 82(ii)] In a process for washing minerals &c., particularly limestone, to free them from earthy material e.g. clay, a slurry of water and the earthy material is used containing substantially the maximum concentration of suspended solids permitting the slurry to be readily handled as a fluid, said slurry being circulated in a closed circuit through the washer and maintained at the said concentration by withdrawing a small amount from the circuit to waste and feeding in a small amount of water which has been used to wash the minerals &c., already treated with the slurry. For washing limestone the ratio of water to suspended solids in the slurry is substantially 2:1 by weight. In the arrangement described, crushed and screened ore, preferably after treatment for removal of the larger pieces of earthy matter (e.g. in a drum separator), is fed via a shoot 2 into a washing trough 3 which is subjected to vibratory or gyratory motion; where it is washed with slurry from the perforated pipe 4. The slurry carries earthy material through the perforated base of the trough 3 into tank 5. The washed mineral moves along the trough 3, is discharged into a second trough 7 where it is washed free of slurry by clean water issuing from the perforated pipe 8 the washed off slurry entering tank 5, and is finally discharged on to a conveyer 10. In the tank 5 the larger particles of solid matter together with mineral fines settle and are removed by the scraper conveyer 11 and discharged to waste at 12, the supernatant slurry overflowing a sill 13 whence it is pumped up to the pipe 4, whilst a small amount of the heavy slurry is discharged to waste by the pump 16, the rates of said discharge and of addition of clean water being adjusted to maintain the required fluidity of the slurry. Alternatively the slurry from the washer may pass through a fine screen, for example in the form of a band conveyer, which retains the larger particles and thence into the tank 5. Specification 581,610 is referred to.