Boliden Aktiebolag

Goran Lindkvist

Arne Bjornberg

Karl G Bjorling

S Ake Holmstrom

The invention relates to a method for preparing a sulphidic concentrate which is intended for further processing to copper and/or precious metals and which contains high percentages of arsenic and/or antimony, and possibly also bismuth in quantities likely to disturb subsequent processing stages, by partially roasting the concentrate in a fluidized bed, so as to eliminate substantially all the arsenic present and a major part of the antimony and/or bismuth. According to the invention, the concentrate and gas are supplied to a fluidized-bed reactor, and are there heated to a minimum temperature above the splitting or decomposition temperatures of the complex minerals containing arsenic and/or antimony and bismuth present in the concentrate. The oxygen potential in the reactor is regulated, so as to prevent the formation of non-volatile compounds of said impurities. The residence time of the concentrate in the reactor is controlled in a manner to ensure a given minimum elimination of the impurities. The gas and solids are withdrawn from the reactor and passed to a separating means, in which substantially impurity-free solids can be separated from the gas. The aforesaid minimum temperature and said regulated oxygen potential are maintained while the solids are in contact with said gas, and at least a part of the separated solids is returned to the reactor, for controlling the residence time, and an end product is removed from the fluidized bed and/or the separating means. The method is suitably carried out in one stage in a fluidized-bed reactor having a circulatory fluidized bed, although in certain cases the method can be carried out in two stages, in mutually separate reactors.

Method for processing copper smelting materials and the like containing

The invention relates to a method for continuously separating a hypoeutectic solution into two parts, of which parts, one comprises practically pure solvent and the other a solution which has a higher content of the dissolved substance than the original solution. In accordance with the invention, the starting solution is held in an elongate vessel at a temperature, which, at least at one end of the vessel, lies immediately above the melting point of the solvent, and cooling elements are caused to move in the vessel towards said one end thereof. The temperature of said cooling elements is alternated to levels above and beneath the liquidus temperature of the solution, so that said elements are alternately coated with a layer of frozen solvent having a lower content of the dissolved substance than the ambient solution, and freed from said coating by melting the coating in a warmer region of the solution, wherewith more solvent than dissolved substance is constantly transported to said one end of the vessel, and the residual solution enriched in the dissolved substance is forced in counterflow towards the other end of said vessel. Solvent and enriched solution is tapped from respective ends of the vessel, while charging to said vessel further solution, at a location where the concentration of the solution is the same as that of the starting solution, thereby to maintain a steady state in the system. The ingoing solution may be a metal alloy, in which case it is divided into two metal melts; an aqueous solution in which case it is divided into water and a more concentrated aqueous solution; or an organic solution, in which case it is divided into a solvent and a more concentrated organic solution.

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Skelleftehamn, Sweden

Goran Lindkvist