GB559264A - Improvements in coal cleaning by the sink-and-float method - Google Patents

Abstract

559,264. Cleaning coal. HANCOCK, R. T. May 8, 1942, Nos. 6246 and 9849. [Class 82 (ii)] In the separation of coal from dirt in a medium of intermediate specific gravity which is maintained of the required value without the use of mechanical agitation, a dispersion of sand in water is continuously fed to the top of a separating vessel in quantity more than sufficient to supply the water in the separating vessel with as much sand as it can abstract, the excess constantly overflowing the top of the vessel. Water may be continuously supplied, to a progressively narrowing downward extension of the separating vessel. In the plant shown, coal, along with a portion of the dispersion, is fed by a shoot 2 to a separating vessel 1, and the floating coal and excess dispersion overflow at a weir 3 with the aid of paddles 4. Dispersion is also supplied through launders 5 fed by a pipe system 6. Water is supplied through pipes 9 to a pyramidal extension 7 which is in communication with a water head 36 and with an adjustable weir 13 through which dispersion from the vessel 1 overflows and is pumped to a tank 16 from which it is recirculated to the pipes 6. The tank 16 communicates also with a medium-cleaning section 28 through outlets 34, 33, the latter being controlled by a valve 39 actuated by a float 37 in the vessel 36. The cleaned coal is washed and drained at 23, the fouled medium being pumped to a tank 26 from which the lightest portion overflows at 27 while the remainder is passed to the cleaning section 28 through a pipe 29. Dirt is removed from the bottom of the separating vessel by an elevator 17 and is screened and washed at 19, recovered medium being pumped to the tank 16.