Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Patent
1995-04-27
1997-03-04
Andrews, Melvyn
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
75629, 75643, 75656, 75696, C21B 1100, C22B 1500, C22B 2300
Patent
active
056074956
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the oxygen smelting of copper sulphide ore concentrates, nickel sulphide ore concentrates or bulk copper and nickel sulphide ore concentrates, and is particularly concerned with the direct oxygen smelting of those of such concentrates which have a high intrinsic energy value.
Existing copper smelting technologies include:
For those concentrates with relatively low intrinsic energy value (i.e. those where large net amounts of exothermic heat are not generated), high level oxygen enrichment can be used with the above technologies, and in certain cases depending both on the existence of high copper/sulphur ratio and a low sulphide iron content in a bornitic concentrate, it is possible to produce blister copper directly in a single step using technically pure oxygen ie oxygen of commercial purity (95% or higher).
Typical chalcopyrite copper concentrates, on the other hand, when oxidised directly to blister copper, generate reaction heat in excess of that required for autogenous operation, even at low levels of oxygen enrichment. The inability to dissipate this additional heat with current used technology prevents or complicates the use of higher levels of oxygen enrichment.
Besides the excess heat generation problem already referred to, single step smelting of copper concentrate with relatively high levels of certain impurity elements (Arsenic, Antimony and Bismuth) tend to produce final blister copper with unacceptable levels of these impurities because their elimination is generally lower than by conventional smelting routes. As a consequence direct smelting to blister copper has to date been restricted to relatively clean concentrates.
GB-A-2048309 (corresponding to EP-A-016595 and U.S. Pat. No. 4,334,918) discloses a process for recovering nonferrous metals from their sulphide ores wherein a molten sulphide carrier composition (or matte) is forcibly circulated through an extraction circuit from which the non-ferrous metal or its sulphide can be continuously extracted at an elevated temperature. The method involves introducing the sulphide ore into the matte at an ore-receiving station so that the ore is dissolved in or melted by the matte, and contacting the matte containing said ore with oxygen at an oxidation station so as to oxidise at least part of the ore and/or the matte, heat generated during the oxidation step being recovered by the matte and transmitted thereby to endothermic sites in the circuit. GB-A-2048309 is not so concerned with copper sulphide ore concentrates having a high intrinsic energy value, but it does disclose the treatment of a copper-zinc ore concentrate containing 25.6% copper, 10% zinc, 1.7% lead, 24% iron and 33% sulphur. With such an ore concentrate, oxidising is effected in an oxidising unit divided into first and second parts wherein a major part of the matte passes through the first part and is oxidised by oxygen lances located above the circulating stream, the oxidation being controlled so that only preferential oxidation of the ferrous sulphide occurs. A minor portion of the matte is directed through the second part where it is top blown with oxygen-enriched air so that both Iron and copper. sulphides are oxidised to produce a molten copper phase as well as a slag phase containing iron oxides and some dissolved cuprous oxide. The molten copper phase produced in the second part is separated so that part can be extracted as blister copper and the remaining fed back to a de-zincing vessel. After passing through the second oxidising part, the remaining matte and slag phases are re-mixed in a cascade fashion with the main matte stream in a slag cleaner, with coal being introduced into the re-mixing region so as to reduce the oxygen potential of the slag and hence decrease the solubility of the cuprous oxide in the slag. Further slag cleaning is provided by addition of iron pyrites to the slag. It will be appreciated that, because such a copper-zinc ore concentrate has a relatively high zinc content, it cannot be regarded as an ore concentrate having a
REFERENCES:
patent: 4334918 (1982-06-01), Warner
patent: 4701217 (1987-10-01), Warner
Andrews Melvyn
The University of Birmingham
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