Boliden Aktiebolag

Sven A Holmstrom

Leif Johansson

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 an improvement in a method for recovering metal values from copper-containing and/or precious-metal containing materials which also contain antimony and/or bismuth in such high quantities as to render working-up of the materials with conventional metallurgical processes difficult or impossible. In accordance with the improvement, the material is subjected to a chlorination volatilization process in a manner to bring the antimony and/or bismuth content of the material to a predetermined low level acceptable for the continued working-up of the material in conventional process stages, while maintaining the metal values of the material in a substantially unaffected form. The volatilization process is best carried out at temperatures of between 450.degree. C. and 750.degree. C., preferably between 550.degree. C. and 650.degree. C. The chlorination process can be carried out on materials included in the group: sulphidic or oxidic-ore concentrates, matte, speiss, oxidic and metallic intermediate products. In certain cases it is convenient to convert the material to another form within the group, for example the matte, prior to carrying out the chlorination process.

Method for recovering metal values from materials containing copper

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.

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Ursviken, Sweden

Sven A Holmstrom