GB238962A - Improvements in or relating to the electro-chemical treatment of copper ores - Google Patents

Abstract

238,962. Mackay, H. S. May 29, 1924. Roasting; solids, treating with liquids. - An electrochemical process for extracting copper from sulphide ores and concentrates comprises roasting the ore, leaching to obtain copper sulphate solution, purifying the solution, and electrolyzing, the roasting and purifying being so regulated as to obtain a liquor of uniform composition. The roasting may be effected in the furnace described in Specification 205,528 or in a standard 7-hearth roasting furnace, preferably modified as shown in Fig. 2. Heat from any source or hot air from the air cooling system of the furnace is added to the lowest hearth by a pipe b and a by-pass pipe a is arranged so as to take off some of the gases from the lower hearths direct to the chimney without passing through the upper hearths, so as to secure a sufficiently high temperature in the lower hearths without overheating the upper hearths. The roasted material is leached in tanks F, preferably with two solutions of different acid content, the first leaching being with a liquor of low acid content and high specific gravity so as to obtain a substantially neutral solution in a tank G, and the second with liquor of higher acid content and lower specific gravity which after use is collected in a tank H. The liquor in the tank H receives acid from a tank N and is then used as the first liquor for a fresh batch of ore. The liquor from the tank G is led to a store tank T and thence to an agitator I in which it is treated with an oxidant such as air and a purifying agent which may be calcium carbonate when it is desired to remove some sulphate radical as well as iron and aluminium, or copper oxide or carbonate ore or copper hydrate when it is desired to remove iron and aluminium without removing any sulphate radical. The liquor from the agitator I is led to a filter K, the filtrate passing to a tank L and thence to a tank P where it receives an addition of acid if desired from the liquor coming from the electrolysers M so as to standardize it before it passes to the electrolytic cells. The rest of the liquor from the electrolyzers M is led to the tank N for use in leaching the ore. The residues in the leaching tanks F are freed from leaching liquor in the following manner :-When the leaching liquor has flowed through so as to expose the top of the ore, the bottom outlets are closed and water is added in quntity equal to that of the solution contained in the ore mass. The outlets are then opened, and the water displaces the solution downwards. Specifications 26138/13 and 194,353 are also referred to.