GB821377A - Improved method and apparatus for extracting ores and like solid substances - Google Patents

Abstract

<PICT:0821377/III/1> <PICT:0821377/III/2> Soluble constituents are extracted from ores and similar solids by introducing the ore into the first of a series of tanks and moving the solid through the tanks as a suspension in countercurrent to a solvent stream. In the example quoted, potassium chloride is extracted from an ore containing both potassium and sodium chlorides, by allowing a hot, saturated sodium chloride solution to flow down a series of tanks 5 (Fig. 2) under gravity and passing the granulated ore up through the tanks as a suspension by means of the impellers 12 which comprise two sets of vanes 15 and 16 (Fig. 3) surrounded by stationary vanes 19, mounted coaxially on a common vertical shaft 13 and separated by a plane baffle 17, the lower vanes pumping the liquid and suspended solid from the preceding tank through the cock 37 and pipes 32 and 20, and the upper vanes agitating the liquid and suspended solid in the upper portion of the tank. Each tank is provided with a weir 25, an outlet 27, an offset settling zone 23 to prevent solid particles being carried down the series of tanks with the solvent and a steam coil 22 to maintain the temperature of the solvent near to its boiling-point. The granulated ore is fed to the system through the hopper 7 and the solvent through the pipe 8, whilst the potassium chloride rich liquor is withdrawn at 9 and the treated ore is removed through pipes 36, weir 35, de-watering apparatus 10 and the chain conveyer 11.