GB445501A - Process for the preparation of basic copper sulphates and ammonium sulphates - Google Patents

Abstract

<PICT:0445501/III/1> Basic copper sulphates are obtained by treating copper or a copper bearing material, in the presence of air or oxygen and ammonia, with a sulphur-oxygen compound of reducing character such as sulphur dioxide and separating the basic sulphates so formed. Alternatively, the treatment in the presence of air or oxygen may be effected by means of a solution of a sulpho-ammonium compound or compounds of reducing character such as ammonium sulphite, bisulphite, thiosulphate or hydrosulphite. The copper may be in the metallic form or in the form of oxides or alloys. The liquors from the reaction containing ammonium compounds may be returned to the process, if necessary after the addition of sulphur dioxide and ammonia. The ammonium sulphate accumulating in the liquors may be recovered continuously or intermittently, for example by precipitating the metal sulphur compounds by means of sulphur dioxide. The basic sulphates formed may be treated with sulphuric acid to neutralize the ammonia and filtered. The basic sulphates separated by filtration may be dissolved in sulphuric acid to obtain normal copper sulphate. The sludges or liquors may be treated with a base such as lime, the evolved ammonia being returned to the process, while the mixture of basic copper sulphates and calcium sulphate being drained and dried to give an anticryptogamic product to which inert substances or adhesives such as dextrine may be added. The liquors containing ammonium sulphate and copper compounds may also be treated with milk of lime to yield ammonia which is returned to the process as ammonium sulphite and an anticryptogamic powder. Copper in the form or scrap or hollowshot is placed in a tower 1 provided with a false bottom 2. Air or oxygen is introduced through a pipe 3 and a solution of ammonium sulphite containing free ammonia through a pipe 7. Excess of air carrying some ammonia flows away through a pipe 8 and is treated with water and sulphur dioxide in a scrubber 9, the resulting aqueous ammonium bisulphite being returned to the reaction through a pipe 10. The sludges collecting at the bottom of the tower are removed through an opening 5 and settled in a tank 11, the clear liquid being returned to the tower through a pipe 12 after its ammonium sulphite content has been restored. Ammonium sulphate may be recovered from the liquid as already described.ALSO:The sludges or liquors containing basic copper sulphates, obtained by acting on copper or a copper bearing material with ammonia and sulphur dioxide, or ammonium sulphite, bisulphite, p thiosulphate or hydrosulphite, in the presence of air or oxygen, are treated with a base such as lime, the resulting mixture of basic copper sulphates and calcium sulphate being drained and dried to give an anticryptogamic product to which inert substances or adhesives such as dextrine may be added.