GB510322A - Improvements in or relating to separation by froth flotation - Google Patents

Abstract

510,322. Concentrating ores &c. EARLE, T. Jan. 27, 1938, No. 2657. [Class 82 (ii)] In the concentration of ores and similar materials by froth flotation the comminuted ore is conditioned with at least one flotation reagent while in a moist state, by which is meant a state in which the moisture content is in excess of that which the material would absorb from the air under normal atmospheric conditions but less than is necessary to produce water films of the maximum thickness on all of the liberated particles. No interstitial water must be present. If the material is initially wet it must be dewatered by a process more drastic than draining, i.e., one involving evaporation, to get it to the moist state ; the dewatering may be regulated to leave the required amount of water, e.g., 0.1-8 per cent., or the material may be completely dried and the necessary water added. The upper permissible water content depends on the size and nature of the particles and is never more than 8 per cent. by weight. The moist material is then thoroughly mixed with a flotation reagent, which may be a collector, e.g., fatty acids, soaps, xanthates. aerofloat &c. or a modifying agent such as sodium sulphide, copper sulphate, cyanide &c. and may be left to stand for some time. It is then transferred to the flotation cell, further flotation agents being added if necessary, and the separation effected in the usual way. If the flotation agent added to the moist material is in aqueous solution or if an acid such as sulphuric acid is added with the flotation agent the moisture content of the ore must be regulated so that after addition of the reagents the ore is still in the moist state. By conditioning the ore in a state in which the particles are incompletely filmed with water the absorptive powers of the particles for the flotation reagents are modified ; moreover the reagent, when soluble, is present as a very concentrated solution. The process can be used for all types of minerals including sulphide ores, but is particularly applicable for ores &c. whose absorptive powers for flotation reagents are normally small, e.g., oxides, silicates &c. Numerous ores are referred to and the following concentrations are described :-(a) an ore containing chrysocolla and malachite with a quartz gangue which is crushed, waterregulated to 2 per cent. water content, mixed with sodium oleate, dithiophosphoric acid, and sodium sulphide, and then floated with addition of terpineol and potassium xanthate ; (b) a chromium oxide ore with silica gangue which is water-regulated to 3 per cent. water content, mixed with oleic acid and terpineol, and then floated ; (c) an ore containing oxidized chalcopyrite, bornite, copper oxides, and quartz gangue, which is water-regulated to 3 per cent. water content, mixed with potassium xanthate, sodium sulphide, and dithiophosphoric acid, and floated to remove the bornite, copper oxides, and some chalcopyrite, potassium xanthate and terpineol being then added to the cell and the chalcopyrite floated ; (d) a beryl ore with feldspar and quartz gangue which is regulated to a 1 per cent. water content, mixed with oleic acid and terpineol, and then floated. With some spongy ores, e.g., phosphates, manganese oxides, and carnotite, the moist ore may be mixed with reagents such as kerosene, crude oil, or castor oil, to fill the pores before the flotation reagent is added. Specification 510,323 is referred to.