GB728520A - Improvements in or relating to manufacturing and using a copper compound containing copper hydroxide - Google Patents

Abstract

A precipitate comprising more than 80 per cent of copper hydroxide, prepared by reacting aqueous ammonia with aqueous copper sulphate at a pH of 7-9 at or below 30 DEG C., is separated by filtration from the liquid, washed and converted to a slurry containing 10-30 gms. Cu/100 ccs.; the copper content is measured and ammonia is added, followed by cellulose to form a spinning solution. The solution may contain less than 40 per cent by weight of copper as metal with respect to the cellulose content.ALSO:Aqueous copper sulphate is reacted with aqueous ammonia at a pH of 7-9 at or below 30 DEG C. to provide a mixture containing in general more than 80 per cent. of the copper as hydroxide. Of the remainder, part at least, is basic copper sulphate. The reagents are added in the requisite proportions and the mixture agitated vigorously to assist exact pH control. The copper sulphate contained in the mother liquor may be recovered by adding sufficient sulphuric acid to reduce the pH to 6-7, separating the so-formed precipitate of basic copper sulphate, adsorbing copper/salts remaining in the solution, e.g. on carbon or ion exchange resin in a column, separating the adsorbed compounds, and treating the precipitate of basic copper sulphate and adsorbed copper compounds with sulphuric acid; the copper sulphate thus regenerated is recirculated with fresh material to produce more of the hydroxide-containing mixture. Crystalline ammonium sulphate may be obtained from the mother liquor after concentration. The hydroxide-containing mixture is filtered, washed and converted to a slurry containing e.g. 10-13 Cu/100 c.c. The copper content is measured, the suspension mixed with aqueous ammonia, and cellulose dissolved in the so-formed cuprammonium solution.