Abstract: The invention relates to a process for recovering non-ferrous metal values such as nickel, cobalt, copper, zinc, manganese and magnesium from material containing said metals, by converting the non-ferrous metal values into sulphates by using melt and melt coating sulphation and recovering them as metal compounds by a process entity based on a melt and melt coating sulphation.

Abstract: Mercury is removed from sulfuric acid-bearing hot and moist smelting-plant or roasting-plant gases by cooling and scrubbing the hot gases by means of a concentrated sulfuric acid mist in order to sulfatize the mercury and to separate it from the gases. The cooling is carried out by vaporizing so much water or dilute sulfuric acid solution from the gases that the temperature of the gas drops to below the dew point, in order to produce a sulfuric acid mist which sulfatizes and washes the mercury, the gases being separated from the mist and directed to the sulfuric acid plant. The process can be carried out by means of nozzles installed in the pipe which feeds hot and moist sulfuric acid-bearing gases into the scrubbing tower of the sulfuric acid plant, water or acid obtained from the scrubbing tower being fed through the nozzles into the feed pipe in the form of a finely-divided mist.

Abstract: A process for the recovery of valuable metals from roasted crude-oil sulfur-extraction catalyst waste is disclosed. In this process the value metals can be separated from aluminum in a single stage by treating the waste at elevated temperature and pressure with such an amount of sulfate solution that the waste dissolves and the aluminum simultaneously precipitates as alunite, which is separated from the solution which contains the other value metals. A sulfate solution is preferably added in such an amount that the concentration of sulfuric acid in the solution is 2-30 g/l at the end of the stage.

Abstract: A process is disclosed for the recovery of lead, silver and gold from the iron-bearing residue of an electrolytic zinc process by froth-flotating a slurry of the iron-bearing residue in the presence of a sulfidic collector agent in order to froth-flotate the sulfides and to separate them from the iron-bearing residue. The iron-bearing residue is sulfidized selectively in order to convert the lead, silver and possibly gold substantially quantitatively to sulfides before the iron-bearing residue is froth-flotated.

Abstract: Zinc, copper and cadmium are recovered from their ferrites by subjecting the ferrites to a sulfuric acid bearing solution in the presence of potassium, sodium or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C. to precipitate the iron present in the ferrites as jarosite, separating at least a portion of the jarosite-bearing solid material from the solution before recycling the solution to a neutral leach, from which a copper and cadmium bearing solution is recovered and to which acid and calcine are also fed, feeding the solid obtained from the neutral leach to the said ferrite treatment stage classifying the solid obtained from the neutral leach into a finer and coarser fraction, feeding the finer fraction to the ferrite treatment stage, comminuting the coarser fraction by grinding, leaching or milling and recycling the comminuted fraction to the process.

Abstract: The impure jarosite residue of an electrolytic zinc process is leached in a sulfuric-acid-bearing solution in order to produce a leach residue which contains lead, silver and gold and a ferrisulfate-bearing solution and to separate them from each other, whereafter the leach residue is sulfidized and froth-flotated in order to recover a combined concentrate which contains lead, silver and gold, and the ferrisulfate-bearing solution is fed to a ferritic treatment stage, in which ferrisulfate and ferrites react in the presence of ions of alkali and ammonium at 80.degree.-105.degree. C. and form pure jarosite and zinc sulfate.

Abstract: A hydrometallurgical process for the treatment of a raw material which contains oxides and ferrites of zinc, copper and cadmium is disclosed, wherein the raw material is neutral leached by means of a sulfuric-acid-bearing solution to leach the oxides without substantial dissolving of the ferrites, a ferrite-bearing residue is separated, and a sulfuric-acid-bearing or ferrisulfate-bearing solution is mixed with the residue in order to leach the ferrite and to precipitate the iron in the form of jarosite in the presence of alkali or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C., and the solid phase is separated from the solution.

Abstract: A process for the treatment of a raw material which contains oxides and ferrites of zinc, copper and cadmium is disclosed, in which the raw material is neutral leached with a sulfuric-acid-bearing solution in order to leach the oxide without substantial dissolving of ferrite, the ferrite-bearing residue is separated, and a sulfuric-acid-bearing or ferrisulfate-bearing solution is mixed with the residue in order to leach the ferrite and to precipitate the iron as jarosite in the presence of alkali ions or ammonium ions under atmospheric conditions at 80.degree.-105.degree. C., the sulfuric-acid-bearing or ferrisulfate-bearing solution being added to the ferrite-bearing residue in such an amount that approximately 50-60% of the ferrite dissolves and its iron precipitates as jarosite, the solid phase is dried and heated to so high a temperature that the zinc of the solid phase is converted to zinc sulfate and its iron to hematite according to the following reaction:(8) 3ZnFe.sub.2 O.sub.4(s) +2A[Fe.sub.3 (SO.

Abstract: A process for the treatment of raw materials which contain arsenic and metal to produce a metal-free arsenic product and an arsenic-free metal sulfate is disclosed, in which the raw material is leached by using an aqueous solution of sulfuric acid and then the metals are crystallized as sulfates from the separated aqueous solution, which is separated from the metal sulfate crystals. The leach is performed at elevated temperature under oxidizing conditions, in order to bring the arsenic to a 5-valent form, the metal sulfates are crystallized out from the selectively separated, arsenate-bearing aqueous solution by cooling, and arsenic is removed from at least part of this aqueous solution before the aqueous solution is returned to the leach.

Abstract: A hydrometallurgical process for the treatment of a raw material which contains iron and other metals, with a sulfuric acid solution, in order to dissolve the metals and to precipitate and separate the iron, the separated metal sulfate solution being exposed to evaporation in order to crystallize and separate the metal sulfates from the mother liquor, which is recycled to the treatment stage performed with sulfuric acid solution, and the separated metal sulfate being recovered.

Abstract: Cobalt is recovered as a finely-divided and anhydrous salt from impure, nickel-bearing, aqueous solutions of cobalt, by exposing the aqueous solution to oxidation at an elevated temperature in the presence of ammonia and the respective ammonium salt, the formation of cobalt (III) hexammine ions is catalysed with activated carbon or solid sulfides, a cobalt (III) hexammine salt is crystallized from the solution, the salt is separated from the solution and pyrolysed to form a cobalt (II) salt, and the released ammonia is returned to the oxidation stage.

Abstract: Extra fine cobalt powder is manufactured by pyrolysing a cobalt (III)hexammine salt and then reducing the obtained oxide.