Abstract: A process for the exploitation of low-grade oxidic and iron-bearing complex ores or concentrates, whereby the initial materials are reduced in a rotary kiln at a temperature of 1000.degree.-1500.degree. C. in such a manner that the products are a magnetic fraction primarily consisting of iron, and a non-magnetic oxide fraction, the materials present in this fraction being further exploitable by conventional methods.

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: Coke or activated carbon is produced from a moist organic substance, for example from a residue from the production of furfural. Initially the moist organic substance is introduced together with hot flue gases into a drying zone of a cylinder furnace and the organic substance is mixed with the hot gases and dried according to the co-current principle. Subsequent thereto the dried substance and the gases are directed into a coking zone of the same furnace, an oxygen-bearing gas also being introduced into said coking zone and the volatile constituents of the organic substance being reduction burned according to the co-current principle so as to produce a coked product. When coke is to be produced, said coked product is withdrawn together with gases from the trailing end of the furnace and the gases are separated therefrom.