Improvements in and relating to methods of and apparatus for separating minerals of high specific gravity in particular noble metals from finely ground rocks or ores

摘要

397,319. Washing granular materials. RAUSCHENBUSCH, C. T. and RAUSCHENBUSCH, F., Kirchen-on-Sieg, Germany. Oct. 11, 1932, No. 28329. [Class 82 (ii).] To separate from raw material finely divided particles of minerals of high specific gravity, particularly noble metals such as gold, platinum, &c., the raw material is subjected to a continuously flowing upward current of water to wash away mud and slime, the velocity of flow of the washing water is then reduced but is still maintained at a value sufficient to keep the material in the washing vessel, and a temporary back pressure or resistance to the flow is then produced to drive the heavier particles downwards or allow them to sink out of the washing vessel into a collecting vessel, any lighter particles which may have been driven down with the heavy particles being returned to the washing vessel on release of the back pressure. The production and release of the back pressure may be repeated several times and the velocity of flow is then increased to remove any remaining lighter particles from the collecting vessel. A funnel-shaped washing vessel A is connected to a water supply pipe E through a stop cock B, a narrow tube C, rubber connecting tubes H, and a U-shaped collecting vessel F. The upper end of the washing vessel is connected to an overflow pipe D to which is attached a long flexible tube G. Water is introduced by a pipe R through a cock K to a pipe N which projects upwardly into a chamber M to the bottom of which the supply pipe E is connected. The space S in the upper part of the chamber M can be connected to the atmosphere by a pipe O with a cock P. In operation the cock B is closed and the cocks K, P opened so that water flows into the vessel F and the supply pipe E, and rises in the chamber M up to the top of the pipe N. The cocks K, P are then closed, the raw material mixed with water is introduced into the vessel A, and the cocks K, B opened, the cock K being first opened wide to agitate the material and then throttled to produce a steady upward flow through the vessel A which is allowed to continue until the overflow is clear of mud and slime. The velocity of flow is then reduced by means of the cock K so that the material in the vessel A remains in suspension just above the cock B. By raising the flexible tube G a back pressure is produced which forces the heavier particles through the tube C into the collecting vessel F. The tube G is then lowered to wash any lighter particles back from the vessel F to the vessel A. The raising and lowering of the tube G may be repeated 20 or 30 times. The velocity of flow is then slightly increased and preferably small variations in back pressure are produced by slightly raising and lowering the tube G several times to effect a final purification of the concentrate in the vessel F. The flexible tube G for varying the back pressure may be replaced by one or a combination of the means shown in Figs. 2, 3, and 4. Fig. 2 shows an externally operated piston T operating in a cylinder U connected by a pipe O to the air space in the chamber M. In Fig. 3 a cylinder U with a piston T is provided between the top of the vessel A and the discharge pipe V, and in Fig. 4 the discharge pipe leads into a cylinder W with an outlet X, the surface of the water being acted on by a spring-pressed piston Z. The presence of the chamber M in the water supply prevents the presence of air bubbles in the water supplied to the collecting and washing vessels.