Copper converting

Details Copper converting Copper converting

1996-12-13

1999-03-30

Andrews, Melvyn

Specialized metallurgical processes, compositions for use therei

Processes

Free metal or alloy reductant contains magnesium

75377, 75644, 75645, C22B 1506

Patent

active

058882707

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates to a process for producing blister copper using a submerged lance.


BACKGROUND OF THE INVENTION

The traditional process for extraction of copper from copper containing ores involves smelting to form a matte and then converting to form blister copper.
The conversion of copper matte is carried out in a Pierce Smith Converter, a process having increasing difficulty meeting environmental standards. The Pierce Smith converter routinely produces copper having a low sulphur content (<0.1 wt % S).
In recent years, lance technology has been developed which has the advantage of allowing high furnace throughput at comparatively low capital cost and with lower cost and increased effectiveness in meeting environmental standards. This technology has been applied to smelting and converting continuously in separate furnaces or successively in a single furnace.
In one such process copper sulphide matte is continuously oxidized to produce blister copper and slag by means of non submerged vertical lances directed onto the surface of a shallow large diameter furnace bath ("Mitsubishi Process"). Under typical operating conditions, the blister copper has a sulphur content in the range of from 0.1 to 1.0 wt %.
It is desirable to minimise the sulphur content of blister copper as even a small increment in the sulphur content is disadvantageous in the anode furnace downstream of the converter. Lower sulphur content can be obtained with the Mitsubishi process but this generally results in an increase in the percentage of copper which reports to slag and must be recycled thus reducing the overall efficiency of the process.
Theory predicts that there is an equilibrium concentration of sulphur in the blister copper at a given concentration of copper in the slag. However, it has not been possible to operate the known lance processes so as to obtain a low sulphur content (that is to say a sulphur content approaching the calculated equilibrium value) and the sulphur content in the blister is typically more than twice the predicted equilibrium sulphur content for any given copper-in-slag concentration.


DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a lance based process which is able to produce blister copper of a lower sulphur content for a given copper-in-slag concentration than such processes presently produce.
It is an object of preferred embodiments of the invention to provide a means for control of a lance based copper converting process which will allow blister copper of a desired low sulphur content to be reliably produced. According to one aspect, the invention includes a process for converting a copper sulphide matte and/or a copper sulphide concentrate to blister copper comprising the steps of: agitated continuous molten slag phase into which the matte and/or concentrate is dispersed, and with which the matte and/or concentrate rapidly reacts, the continuous slag phase floating on a continuous molten blister copper phase, an interface being located between the continuous slag phase and the continuous blister copper phase; reacting with the matte or concentrate to form a blister copper containing a low sulphur content blister, slag and sulphur dioxide; depth selected in relation to said slag/blister copper interface so as to ensure that a substantial portion of the gas contacts the blister copper phase; and
Desirably, the controlling step comprises the step of adjusting the depth of immersion of the lance tip relative to the altitude of the surface of the blister copper layer. In highly preferred embodiments of the invention the bath is deep in relation to its width, for example, the depth to diameter ratio is on average, greater than 0.2.
According to a second aspect, the invention includes a process for converting a copper sulphide matte and/or a copper sulphide concentrate to blister copper comprising the steps of: agitated continuous molten slag phase into which the matte and/or concentrate is dispersed, and with which the matte and/or con

REFERENCES:
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patent: 3832163 (1974-08-01), Themelis
patent: 3890139 (1975-06-01), Suzuki et al.
patent: 4308058 (1981-12-01), Makipirtti et al.
patent: 4830667 (1989-05-01), Marcuson et al.
patent: 5281252 (1994-01-01), Landolt et al.
Derwent Abstract, Accession No. 61621A34, SU 274915A (Gipronikel Res. Inst.), 10 Dec. 1977.
Derwent Abstract, Accession No. 93-074219/09, SU 1721109A (Lengd Plekhanov Mine), 23 Mar. 1992.
Derwent Abstract, Accession No. 92-022174/03, SU 1625896A (Sibe Sibtsvetmetnii), 7 Feb. 1991.

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