Copper processing method

Abstract

A method of processing a copper-containing source material is provided whereby an aqueous acidic leach solution of the copper-containing source material is formed and then contacted with a pH increasing agent to thereby cause the precipitation of a copper-containing intermediate. The copper-containing intermediate can then be collected and exposed to a high temperature treatment, such as would be encountered in smelter or converter operations.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method of processing a copper-containing ore or other source material. Particularly, the present invention relates to a method of processing an ore or source material to recover copper, or a suitable copper compound, therefrom.BACKGROUND TO THE INVENTION[0002]Any reference to background art herein is not to be construed as an admission that such art constitutes common general knowledge in Australia or elsewhere.[0003]Copper is a highly valuable commodity with increased demands being placed on production due, in part, to the rapid growth of economies such as India and China. At the same time the identification of new high grade ore deposits is becoming increasingly challenging.[0004]The majority of copper is extracted from its ores in one of two ways. Most copper sulphide ores are concentrated by flotation and treated using a pyrometallurgical route while other copper ores, for example copper oxide ores and some lower gra...

AI Technical Summary

Benefits of technology

The goal of this invention is to offer a way to work with material that contains copper, addressing any issues or shortcomings that previously existed.

Problems solved by technology

At the same time the identification of new high grade ore deposits is becoming increasingly challenging.

These two methods have some inherent advantages and particular disadvantages that become more profound as lower grade ores are treated.

The heat balance in these process units can be challenging to control and places limitations on the process.

One of the major energy consuming steps in this concentrate smelting route is in the electrical power used for the grinding of the ores.

The pyrometallurgical approach is thus economically limited in the grade of ore it can process.

This is becoming increasingly problematic as the copper content of newly discovered ores is steadily decreasing.

Arsenic is currently a problem in conventional sulphide pyrometallurgy since the process conditions in the first step, the smelting step, result in relatively reducing conditions and the arsenic partitions preferentially to the gas phase as species such as arsenic trioxide or arsenic trisulphide.

This creates significant problems with gas cleaning and disposal of arsenic-containing fume.

If the predominant copper minerals in an ore are not sulphides, the ore is difficult to concentrate by physical means and is unsuited to pyrometallurgical processing as the cost of heating the host rock is prohibitive in terms of energy and cost.

Further, if certain impurities (such as arsenic) in a sulphide ore and resulting concentrate surpass a critical concentration then that ore cannot be treated using the pyrometallurgical processes.

However, a handful of key issues can make the process unsuitable for particular ore bodies.

The capital costs for the solvent extraction and electrowinning circuits are relatively high so the use of the hydrometallurgical process route on some smaller or short lifetime resources can be uneconomical.

Furthermore, the electrowinning step is energy intensive and requires a significant source of electrical power.

As the cost of energy generation increases through increased demand and taxation, the cost of the required electrical power becomes even more prohibitive, especially in remote areas where the required infrastructure is not already installed.

A less obvious but much more technically challenging issue for hydrometallurgical processing is the huge dependence of the process on the proton and sulphate balance.

The fact that the process regenerates sulphuric acid in the electrowinning section is often purported as a major advantage but it can also become a major problem in the situation where the leach circuit is also generating acid.

This is often the case in the leaching of sulphides and results in the need to neutralise a portion of the acid generated.

The required bleed to a neutralisation step results in extra reagent costs, introduces a potential avenue of valuable copper loss and the resulting residue requires environmentally sound storage and disposal.

These issues with the hydrometallurgical process has resulted in ore bodies which contain a copper oxide cap over a more substantial sulphide deposit having the oxide cap removed and discarded or stored rather than being processed and the copper value realised.

As the concentration of copper in these reserves decreases and the concentrations of impurity elements increase the ores and concentrates are becoming increasingly difficult to treat using existing industrial process routes and technologies.

The impacts of these trends are in the form of decreasing productivity, increasing energy consumption and costs, and increasing capital investment and operating costs required to avoid adverse environmental impacts.

It is more difficult to effectively extract copper from such complex ores and concentrates.

For example, these complex ores often have relatively high levels of iron which must be removed at some stage.

Importantly, a percentage of the available copper will always partition into the slag with the iron and greater quantities of slag resulting from the higher levels of iron will inevitably result in a greater loss of copper to slag.

It is clear that, using conventional pyre- and hydro-metallurgy routes, as mean ore grades decrease the capital and operating costs of copper production will increase along with the electrical energy requirements and also the greenhouse gas impact, if the energy used is produced from fossil fuels.

In addition, arsenic is becoming even more of a problem for copper processing as its concentration in many copper ores is increasing while, at the other end, stricter limits are being placed on its environmental release.

Similar issues exist for other impurity elements such as lead, bismuth and a range of radioactive elements.

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