| In this paper, a new method of removing cobalt from zinc sulphate solution is researched. In hydrometallurgy process, conventional removing cobalt method are zinc powder cementation in zinc production, and chlorine and nickelic compound oxidation precipitation in nickel production. But in first process, high grade zinc residue is produced, which is treated difficultly and in other two methods, chlorion or nickel ion will be inducted, so they can be only used in nickel hydrometallurgical processes. Therefore, above three methods are not suitable for acquiring commercial cobalt raw material in removing cobalt from zinc sulphate solution. So, a new process must be investigated.In the research, potassium permanganate is used to remove cobalt. The way of its removing cobalt is oxidation. Though cobaltous ion is oxidized uneasily, it can be fulfilled under the special conditions: higher solution PH, higher temperature and stronger oxidants such as chlorine, nickelic compound, permanganate, etc. When cobaltous ion is oxidized into cobaltic ion, it can be separated from solution as an insoluble deposit, for cobaltic ion hydrolyzes easily at PH>4.0. Hence, as a very strong oxidant, potassium permanganate can precipitate cobalt. Differing from other oxidants,the product of reacted permanganate is insoluble in oxidation process. The reaction between permanganate and cobaltous ion will produce hydrogen ion, consequently the PH of the reaction system will decrease when reaction is doing. Under low PH, the reaction doesn't take place, contrary, cobaltic compound will be reduced into cobaltous ion, and neutralizing agent must be added into the system to neutralize hydrogen ion.In order to determinate the preferable conditions of above reaction, the research is carried out, firstly, with cobaltous sulphate solution, then on the base of it, with the leaching solution of Zn-Co residue from cobalt purification from zinc hydrometallurgical smelter. With cobaltous sulphate solution, the influences of temperature, time, PH, potassium quantity and impurities including Mn2+, Ni2'1", Zn2+ and Cd2+ are researched. It is found that higher temperature, longer time, higher PH and more potassium are beneficial to cobalt precipitation. Thereinto, PH is a key factor, and when PH is high enough, temperature and time have a little affection on reaction. Of impurities, Mn24 can react with permanganate completely; Ni2+, partly; Zn2+ and Cd24, never. When ionic strength is high, the activities of all ions in the solution are influenced. In general, the activities decrease. Therefore, the residual concentration of potassium in the solution with high impurities ionic strength is higher than one in the solution with the same cobaltous ion concentration and without other impurities at the same rate of the cobalt removal. Then, the stoichiometric ratio of the reaction between cobaltous ion and permanganate is determined by potentiometry and X-ray diffraction of the product of the reaction. The results show that the reduced compound of permanganate is mainly Mn02, and the oxidized one of Co2+ is CoOOH, and the molar ratio between cobaltous ion and permanganate is about 3.0. On the base of those, cobalt removal from the leaching solution is investigated. The parameters for cobalt removal of the leaching solution are determined as follows: superfluous concentration of permanganate is lg/1; superfluous concentration of ZnO is 7g/l (used to consume hydrogen ion to retain PH of solution); temperature is 75 C; reaction time is between 30min and 60min.Thus, high cobalt raw material with commercial value can be obtained from this method, in which cobalt concentration is higher than 12%. Besides it, the method has such merits: the rate of cobalt removal is more than 99% and the residual cobalt concentration in the removed cobalt solution is less than lmg/1, short operation time,ivlow cost comparing with other methods such as chlorine, nickelic compound, zinc powder cementation, xanthate and naphthol, no another impurities, easily incorpora...
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