Patent GB-313858-A (GB)
Title: Improvements in and relating to the production of zinc and other metals
IPC: C22B3/06
Filed: 1929-06-17
Abstract: 313,858. Sturbelle, L. June 15, 1928, [Convention date]. Metals, obtaining. - The acid extraction of zinc, iron, or other metals from their ores is effected on the countercurrent principle, the solutions obtained are purified respectively by zinc, iron, or other sulphide, and the metal then recovered by electrolysis. The purification effected on the countercurrent principle by aspirating the impure solution through a cake of the sulphide. The invention is described as applied to the extraction of zinc by sulphuric acid from roasted or oxidic ores and may be effected in apparatus comprising a main extraction tank c, electrolytic purifying baths j, q, a sulphide purifying tank k, electrolytic baths s for recovery of zinc, and electrolytic baths t, u for recovery of separated copper and cadmium. The tank c comprises compartments 1 - - 4, and suction filters d mounted on a rotary support e adapted to be inserted into and to be moved through each compartment in turn. The tank k similarly comprises compartments 1 - - 8 and suction filters l mounted on a rotary support n. The ore is mixed in tanks a and b with feebly acid zinc-rich liquor received by a pipe 9 from compartment 2 of the tank c. The mixture passes into compartment 3 of the tank, the neutral zinc solution is withdrawn by suction to a vessel g and the ore deposited on the filter d in the form of a cake. The cake passes succescively into and through compartments 2 and 1 in countercurrent to exhausted electrolyte supplied to compartment 1 from the cells s by a pipe 26. Manganese dioxide is supplied to the ore to keep iron present in the ferric state. In compartment 4 the residue is detached from the filter by compressed air, broken up on rollers and sent as a water suspension to a separating tank h from which the liquid is sent to a vessel i and the solids to filtering means 35 prior to treatment to recover lead, silver, arsenic or antimony, or iron oxide. From the vessel q the zinc sulphate solution passes to c-ells j where most of the copper, antimony, and arsenic, and a little of the nickel, cobalt, and cadmium is precipitated. The solution with deposited metal particles in suspension then enters compartment 4 of the tank k. A slightly acid suspension of zinc sulphide in water containing chalk is led from a bath o to compartment 1 of the tank and is there deposited as a cake on the filter l. This cake moves successively into and through compartments 2, 3, and 4 in countercurrent to the solution received from cells j. The solution issuing from the compartment 2, containing as impurities only nickel end cobalt and possibly cadmium sulphide in suspension is passed to a draining tank p to remove the latter. Nickel and cobalt are then deposited in the cells q after the solution has been acidified by exhausted electrolyte, and the pure solution, after passage through a filter press r reaches the cells s for deposition of the zinc. In compartment 5 of the tank k, the filter cake containing precipitated impurities is washed by water from reservoir i, and in compartment 6 by hot acid solution circulating between the cells t for deposition of cadmium and this compartment. In compartment 7 the cake is washed, and in compartment 8 the cake is detached by compressed air and passed to a vessel 36 in which copper is brought into solution preparatory to its recovery in cells u. In the cells q for deposition of nickel and cobalt, lead anodes and polished nickel or copper nickel, or graphite cathodes are used ; and in the cells s for deposition of zinc, lead anodes and aluminium or stainless steel cathodes are employed.