Patent GB-602028-A (GB)
Title: Improvements relating to the separation of nickel sulphide from copper sulphide
IPC: C22B15/00
Filed: 1945-02-16
Abstract: Sulphides of copper and nickel, e.g. bessemer matte are separated by controlled cooling of the partly or wholly molten mixture to produce crystals of each sulphide substantially free from the other sulphide, followed by comminution to free the crystals mechanically from each other, and separation.  The precise control of cooling varies with the composition of the mixture, the degree of separation desired and economic considerations.  Cooling should not exceed 50 DEG  F. and preferably 10 DEG  F. per hour from final solidification at 1100 DEG F. to 950 DEG  F., when beta NiS changes to the alpha form and dissolved Cu2S diffuses out.  The 50 DEG  F./hour rate is preferably maintained from the initial crystallisation of Cu2S down to 950 DEG F.  Cooling preferably does not exceed 100 DEG  F. per hour from initial solidification to 200 DEG  F., nor 20 DEG  F. per hour for at least 5 hours between 1200-950 DEG  F.  Rapid cooling in one range may however be partly compensated by slower cooling in another range. Cooling should be slow enough to produce primary Cu2S crystals of at least 0.0006 inch minimum dimension.  Copper nickel scrap may be fused with sulphur to produce the mixed sulphides. The matte may be rapidly cooled, reheated preferably to at least midway between 1100 DEG  F. and the liquidus temperature and then submitted to controlled cooling.  The degree of comminution depends on the size of crystals formed.  Separation may be e.g. a sink and float method, but is preferably by frothflotation in which Cu2S is floated and NiS depressed.  A magnetic Ni/Cu alloy which forms during cooling may be magnetically separated before and/or after flotation during which it distributes between the two fractions.  The cooled mass is preferably ground in water containing lime to produce a high pH, preferably 10-12.4, and flotation agents, e.g. pentasol or other xanthate, diphenyl or p  diortho tolyl guanidine with or without pine oil added.  Sodium silicate may be used as a dispersing agent and sodium cyanide as a depressant.  Several floatation steps may be used with intermediate grinding.  Detailed examples of the cooling and flotation stages for mixtures of various composition are given. The first Provisional Specification refers to separation by electronic sorting or selective solution.ALSO:Sulphides of copper and nickel e.g. bessemer matte are separated by controlled cooling of the partly or wholly molten mixture to produce crystals of each sulphide substantially free from the other sulphide, followed by comminution to free the crystals mechanically from each other, and separation. The degree of comminution depends on the size of crystals formed. Separation may be e.g., a sink and float method but is preferably by froth flotation in which Cu2S is floated and NiS depressed.  A magnetic Ni/Cu alloy which forms during cooling may be magnetically separated before and/or after flotation during which it distributes between the two fraction agents e.g., pentasol or other xan-ground in water containing lime to produce a high pH preferably 10-12.4, and flotations.  The cooled mass is preferably thates, diphenyl or diortho tolyl guanidine, with or without pine oil added.  Sodium silicate may be used as a dispersing agent and sodium cyanide as a depressant.  Several flotation steps may be used with intermediate grinding.  The matte may be rapidly cooled, reheated preferably to at least midway between 1100 DEG C. and the liquidus and then submitted to controlled cooling.  Copper nickel scrap may be fused with sulphur to produce the mixed sulphides.  The precise control of cooling varies with the composition of the mixture, the degree of separation desired and economic considerations.  Cooling should not exceed 50 DEG F and preferably 10 DEG F per hour from final solidification at 1100 DEG F to 950 DEG F when beta NiS changes to the alpha form and disolved Cu2S diffuses out.  The 50 DEG F/hour rate is preferably maintained from the initial crystallisation of Cu2S down to 950 DEG F.  Cooling preferably does not exceed 100 DEG F/hour from initial solidification to 200 DEG F, nor 20 DEG F per hour for at least 5 hours between 1200-950 DEG F.  Rapid cooling in one range may, however, be partly compensated by slower cooling in another range. Cooling should be slow enough to produce primary Cu2S crystals of at least 0.0006 inch minimum dimension.  Detailed examples of the cooling and flotation stages for mixtures of various compositions are given.  The first Provisional Specification refers to separation by electronic sorting or selective solution.