Boliden Aktiebolag

Leif Johansson

Sven A Holmstrom

Stig A Petersson

Bengt O Rudling

Hans G Berg

The invention relates to a method for pyrometallurgically recovering the precious metal content, such as gold, silver and platinum metals, of halogen-bearing materials rich in silver. The material is caused to rapidly disperse in or be finely distributed throughout an at least partially molten charge containing a non-oxidic metal-containing phase having the ability to dissolve precious metals and to substantially lower their chemical activity. The halogen content of the material herewith reacts with any fluxes or metals of high chemical activity present in the furnace charge, while forming metal halogenides. The halogenides formed are separated by slagging and/or volatilization, and the precious metals are recovered from the molten charge, depleted of halogens, in a conventional manner and with regard to the charge phases.

Method for recovering precious metals

The invention relates to a method for recovering the valuable metal content of a mix of contaminated copper raw materials, of which materials at least one is sulphide bearing, and which contain one or more impurities forming the group arsenic, antimony, bismuth, mercury, tin, chlorine and other halogens. The invention is characterized by adjusting the halogen content of the mix so that it is substantially at least stoichiometric in relation to remaining impurities in the group, whereafter the mix is charged to a furnace in which melting can take place and in which the mix is heated to at least 500.degree. C., but beneath the melting points of respective ingredients of the mix, while maintaining good contact with hot gas therewith to expel substantially all of the aforementioned impurities present. The mix is then heated to completely smelt the ingredients present, to form a slag and a copper matte, which latter contains the valuable metal content, whereafter this valuable metal content is recovered with the aid of a suitable, conventional method. At least one of the copper raw materials present in the mix comprises suitably a halogen-bearing valuable-metal containing product, for example chlorine-bearing ash or slag.

Method for recovering the valuable metal content of contaminated copper

The invention relates to a method for recovering the metal values from materials containing at least one of zinc and tin, by smelting the starting materials under oxidizing conditions and reducing the resultant molten bath. The starting materials are first smelted in a furnace while adding flux, to form a slag which is sluggish at selected reduction temperatures and has a low lead contents. The reduction process is carried out while charging solid carbonaceous reduction agent and optionally also sulphur- and/or chlorine-donor material to the slag. The reduction agent and optionally supplied donor material is brought into suspension with the slag, and this suspension is sustained at least during the latter phase of the reduction period, at which the lead content of the slag has fallen to beneath about 1-2%, during which phase the reduction of zinc and tin takes place. Zinc is recovered from the furnace in the form of zinc vapor, while tin optionally is removed as volatile tin sulphide, chloride or oxide, and lead and any other metal values present in the starting materials are recovered as a molten lead phase.

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Skelleftehamn, Sweden

Leif Johansson