Patent GB-716588-A (GB)
Title: Improvements relating to the production of iron oxide from sulphide ores
IPC: C22B23/00
Filed: 1952-06-10
Abstract: In a process in which a nickeliferous sulphidic iron ore is treated to remove nickel with or without other metals from it by the selective conversion of these metals into water-soluble sulphates leaving iron oxide as the residue, treating the ore to produce a concentrate containing not more than 1 per cent. nickel by weight and of particle size such that not more than 5 per cent. is retained by a 200-mesh sieve and suspension-roasting this concentrate in an oxidizing atmosphere at a temperature between 1200 and 1350 DEG F. to produce an active calcine of low sulphur content suitable for the selective conversion into sulphates.  In obtaining a high grade iron oxide containing less than 0.15 per cent. of nickel for the production of iron and steel, a pyrrhotitic ore may be first subjected to grinding and froth flotation treatments (see Group II) whereby the bulk of the nickel, other metals and gangue is removed from the pyrrhotite and the concentrate roasted by flash or fluidized technique to give a product containing less than 0.5 per cent. sulphur. 2 to 8 per cent., preferably 3 to 6 per cent. by weight of powdered sodium sulphate is then added e.g. at the roasting temperature to the calcine and the mixture treated within the temperature range of 1200 to 1300 DEG F., e.g. in a rotating kiln in an atmosphere containing more than 4 per cent. by volume sulphur dioxide, preferably more than 6 per cent.  Optimum proportions are 8 to 12 per cent. by volume sulphur dioxide, and the oxygen content of the gases should not be less than half that of sulphur dioxide and is preferably at least 5 per cent. by volume.  The product which should contain not less than about 85 per cent. of the nickel in the calcine as sulphate is leached with water and agglomerated. The sodium sulphate content of the barren leaching solution from which nickel cobalt and copper have been removed, may be returned to the roasting furnace, e.g. by direct injection or after salting-out, to the sulphate-forming furnace.  An Example is given.  Specification 659,283 is referred to.ALSO:A concentrate containing less than 1 per cent. of nickel is obtained by multistage froth flotation with intermediate grinding and with or without magnetic separation, in a process for the production of iron oxide from nickel-containing iron ores (see also Group III).  In an example, a nickeliferous pyrrhotite ore containing about 20 per cent. pyrrhotite, 3 per cent. pentlandite and 3 per cent. chalcopyrite, the balance being mainly gangue, was comminuted so that 15 per cent. was retained on a 65-mesh seive and subjected to a two-stage froth flotation process to recover a concentrate containing the bulk of the chalcopyrite and pentlandite and a concentrate containing the bulk of the pyrrhotite while rejecting a gangue tailing.  The pyrrhotite concentrate was deslimed and comminuted further so that only 5 per cent. was retained on a 200-mesh sieve.  This concentrate was again subjected to froth flotation to float substantially all remaining chalcopyrite and pentlandite from the pyrrhotite and the final pyrohotite concentrate floated from remaining gangue.  It contained about 2 per cent. silica, 0.85 per cent. nickel and 0.07 per cent. copper. Specification 659,283 is referred to.