Patent GB-190502532-A (GB)
Title: Improvements in the Treatment of Complex Sulphide and Oxidised Ores for the Recovery therefrom of Zinc, Nickel, Cobalt, and Manganese Oxides, and of Copper, Arsenic, Antimony, Lead, Bismuth, Cadmium and Tin.
Inventor: RUMBOLD WILLIAM GEORGE
Filed: 1905-02-08
Granted: 1906-02-08
Abstract: 2532. Rumbold, W. G., Patchin, G., and Hughes, J. W. Feb. 8. Zinc, cobalt, iron, manganese, and nickel oxides; iron and barium sulphates; zinc sulphide.-A new solvent is used for treating complex sulphide and oxidized zinc ores, mainly to obtain pure white zinc oxide, suitable for paint and metallurgical or other uses. The ores are treated direct, or, in the case of sulphide ores, after oxidation by roasting or otherwise, with the solvent, which is stated to dissolve contained cadmium, cobalt, copper, manganese, nickel, and zinc carbonates, oxides, and sulphates, and which consists of ferric sulphate, sulphuric acid, water, and a small proportion of sodium chloride insufficient to dissolve any silver chloride formed. The ore, roasted if necessary, is crushed to pass a forty-mesh screen and treated with the solvent, which is passed over successive lots of ore until saturated, the partially saturated solution coming on to fresh ore and the fresh solution on to partly spent ore. When the solvent is saturated and free from uncombined sulpburic acid, the iron precipitates, chiefly as ferric hydrate, and is filtered off. Where sulphuric acid is not conveniently obtainable, the solvent may consist of sulphurous acid, sodium chloride, and water passed over ore containing ferric oxide, or to which ferric oxide has been added. The sulphurous acid may be obtained, as is known, by passing the furnace gases from the roasting sulphide ores through an absorption tower against a stream of water. When the acid is converted into sulphites, the solution may absorb more sulphur dioxide, and these operations may be repeated until the solution is saturated with dissolved matter from the ore. It is then oxidized by exposure to the air, or by blowing steam, or air, or both, through it. By adding zinc, as dust or otherwise, to the saturated solution of sulphates obtained by either method, any antimony, arsenic, bismuth, cadmium, copper, lead, and tin present are precipitated. After filtering, manganese is precipitated as hydrate by the addition of an oxidizing-agent, preferably an alkali permanganate, in which case the contained manganese is similarly precipitated. Cobalt and nickel are precipitated as oxides by adding a recognized agent such as bleaching - powder. According to the Provisional Specification, the manganese and cobalt are oxidized and precipitated by treatment of the solution with a little bleaching- powder or other oxidizing-agent, and then blowing air through. The last traces of manganese are removed as metal by the addition of a little magnesium. The nickel is precipitated, as hydrate, by heating with an excess of zinc oxide, and is then separated from the latter. Finally, hydrated zinc is thrown down, by the addition of just sufficient ammonia, is filtered off, dried, heated, and prepared for paint &c. The ammonia is recovered by distilling the residual liquors with lime or other alkaline-earth oxides. The zinc may be precipitated as hydrated oxide or sulphide, each mixed with barium sulphate, by using respectively barium hydrate or sulphide. The ferric sulphate may be regenerated by passing an aqueous solution of sulphuric acid and sodium chloride over the spent ores, thus re-dissolving the precipitated ferric hydrate &c.