Integrated hydrometallurgical and pyrometallurgical processing of base-metal sulphides

Abstract

The present invention relates to the recovery of base metals, in particular but not exclusively copper, via integrated hydrometallurgical and pyrometallurgical processing of base-metal sulphides, in particular but not exclusively iron-containing base-metal sulphides.

Description

FIELD OF THE INVENTION[0001]The present invention relates to the recovery of base metals, in particular but not exclusively copper, via integrated hydrometallurgical and pyrometallurgical processing of base-metal sulphides, in particular but not exclusively iron-containing base-metal sulphides.[0002]The present invention relates more particularly but not exclusively to the recovery of copper from iron-containing copper sulphide concentrates in which the copper is present as chalcopyrite and / or bornite, by first processing the initial iron-bearing copper sulphide concentrate feedstock into three separate fractions by means of froth flotation or other beneficiation processes, the fractions being a high-grade concentrate fraction, a low-grade concentrate fraction, and tailings fraction. Typically the high- and low-grade concentrates will have copper contents greater than about 25%, and less that about 25%, respectively. The three separate fractions thereby recovered are individually an...

AI Technical Summary

Benefits of technology

[0064]An advantage of the present invention is that the overall recovery of copper from the original copper-containing feedstock is maximised. An additional advantage is that variable ore blends, concentrate mixtures, or diverse sources of copper ore may be economically treated without the need to dispose of any untreated component of the original feedstock.

[0065]Another advantage of the present integrated hydrometallurgical and pyrometallurgical process flowsheet is the ready transfer of solution products and energy from circuit to circuit so that the chemical efficiency and hence economics of the whole integrated process is improved.

[0066]The integrated hydrometallurgical and pyrometallurgical process flowsheet also facilitates the optimum recovery of by-products including uranium, cobalt, nickel and precious metals, particularly gold and / or silver, contained in the original feedstock.

[0067]The integrated hydrometallurgical and pyrometallurgical process flowsheet also facilitates the transformation of any arsenic contained in the original feedstock into a form that is environmentally benign and can be safely discharged for disposal in a conventional tailings / residue storage facility.

Problems solved by technology

Hydrometallurgical processing routes are generally characterised as being complex with many unit steps and large circulating loads of copper.

Conventional smelting processes are generally not applicable to lower grade copper concentrates.

Roasting is often inefficient because copper-containing insoluble ferrite phases can form during the roasting stage.

Few of the proposed processes have attained full-scale commercial development for a number of reasons, including the need for ultrafine grinding, extended retention times, problems with the generation and neutralisation / precipitation of high ferric iron liquors, difficulties in recovery of any precious metals in the original feedstock, and the generation of relatively dilute copper solutions.

All of these factors increase both the capital and operating costs, especially when applied to relatively low-grade copper (chalcopyrite) concentrates.

The overall copper recoveries from many of the proposed processes is often less than economically acceptable because of incomplete reaction and / or losses to leach residues via precipitation and / or absorption processes.

The recovery of copper from chalcopyrite-containing copper concentrate that also contains an appreciable uranium content is substantially more complex as it is necessary to effect an efficient copper-uranium separation ahead of the recovery of electrowon / electrorefined copper.

Under most hydrometallurgical processing conditions it is difficult to achieve selective leaching of copper over uranium or uranium over copper, so that most hydrometallurgical circuits yield a pregnant copper-uranium solution.

Separation of the soluble copper from the uranium requires the installation and operation of a complex solvent extraction circuit that results in increased capital and operating costs.

The claimed flowsheets are deficient in a number of aspects in that, for example, they do not disclose how the copper sulphate leachant is generated, involve additional flotation steps, require the addition of a reductant to facilitate the process metallurgy, or achieve incomplete conversion (metathesis) to ensure that the resultant discarded acidic ferrous sulphate solution has an acceptably low copper content.

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