Patent GB-755044-A (GB)
Title: Process for the recovery of cobalt
IPC: C01G3/00
Filed: 1954-05-04
Abstract: <PICT:0755044/III/1> <PICT:0755044/III/2> Cobalt is recovered by contacting a waste solution containing divalent iron and divalent cobalt obtained from the iron cementation of cuprous chloride suspension containing cobalt as an impurity, obtained by copper cementation of an aqueous solution obtained by leaching chlorinated roasted burnt pyrites, with a quantity of an impure cobaltic hydroxide sludge more than sufficient to react with the whole of the divalent iron whereby the cobalt is reduced and passes into solution which is separated from the residual sludge.  The cobaltic hydroxide sludge may be obtained as shown in Fig. 1 where the starting solution 1a is obtained by treating with cement copper, copper, zinc and cobalt containing solutions obtained by leaching chlorinated roasted burnt pyrites, thereby precipitating cuprous chloride which is separated and leaving a solution 1a which is treated as shown in the cementation stage of Fig. 1 with scrap iron thereby cementing out the copper (which may be used to precipitate cuprous chloride and form solution 1a, above mentioned) and forming solution 2 containing iron cobalt and zinc which is contacted with air or chlorine to oxidize the iron, which is then precipitated with calcium carbonate and the iron-gypsum sludge removed.  The remaining solution 3 containing cobalt and zinc is oxidided with chlorine and thereafter precipitated with zinc hydroxide.  The precipitated sludge of cobaltic hydroxide is then treated according to the invention whilst the remaining solution 4 containing zinc may be precipitated with milk of lime to yield a calcium chloride solution 5 and zinc hydroxide product.  The cementation solution containing divalent iron, cobalt, copper and zinc which is treated with the cobaltic hydroxide sludge above mentioned may be obtained as shown in Fig. 2 wherein a solution obtained from chlorinated roasted burnt pyrites (solution 1) is cemented with copper to precipitate cuprous chloride and form a solution 1a which is treated as in Fig. 1, and the separated cuprous chloride suspension is acidified with hydrochloric or sulphuric acid to a pH below 1 and cemented with scrap iron. Cement copper is formed and separated and the remaining cementation solution (solution 6) is reacted with the cobaltic hydroxide sludge.  The cementation waste solution at 20 DEG  to 70 DEG C. is passed first to a washing stage, described below, and the solution 6a from this washing stage is mixed with the cobaltic hydroxide sludge precipitated from solution 3 in Fig. 1 where part of the cobalt is reduced and dissolved and the trivalent iron is precipitated in the presence of a small amount of residual undissolved cobalt.  The precipitate, sludge and formed solution may then be treated with sodium sulphide solutions to precipitate copper which is then removed together with the precipitated iron and the undissolved cobalt values, and passed to the washing stage where it is contacted with the incoming cementation solution 6. From the washing stage the iron and copper-containing sludge free from cobalt is removed.  The solution 7 containing the dissolved cobalt values and free from iron and copper may be treated with milk of lime, soda or caustic alkalies in a precipitation stage to produce iron and copper-free cobalt hydroxide which is separated from the residual solution.  The milk of lime employed for this precipitation is preferably iron free and is suitably obtained by treating the calcium chloride solution (5) of Fig. 1 with sodium hydroxide as shown in the lower right-hand corner of Fig. 2.