Abstract: A method of extracting iron and nickel from sulphidic iron-nickel-materials and recover them in metallic form. The method comprises leaching the material with an acidic solution in presence of an oxidizing agent, so that substantially the whole quantity of the oxidizing agent is consumed. The obtained leaching liquid is then divided into two parts and one part is led to the cathode chamber, where iron and nickel is co-electro deposited and the other part is led to the anode chamber were the leaching liquid is regenerated before reuse.

Abstract: A flotation concentrate in the form of a water suspension is treated with a reagent that nullifies the effect of previously used collectors. The suspension is filtered, and subjected to a mechanochemical treatment that includes chemical conditioning of the mineral surfaces and producing fresh surfaces by grinding with grinding bodies which additionally provide ions that promote selectivity. Grinding efficiency is controlled by the amount of material fed to the mill. The quantity of pulp flowing to the filter is determined and the supply of collector reagent to the filter and the rotary speed of the mill are regulated in response to the flow values.

Abstract: A grinding plant for autogenous or semi-autogenous grinding of ores in particular, in separate mills in two steps. The second step uses material from the first step, which is provided with two outlets. The first outlet has holes for discharging relatively finely ground material to be further ground in the second step, and the second outlet has holes for discharging material containing relatively coarse pieces forming grinding media in the second step. A device is provided between the stages to control the flow of coarser material to the second step. Connected to the discharge side of the second step, which is provided with outlet holes as large as the holes for fine material in the first step, there is a means to separate material removed from the second step into a finely ground portion, which is led away, and a portion returned to the first and second steps in proportions adjustable by said means.