MetaLeach Limited is a wholly owned subsidiary of Alexander Mining plc and was formed to enable the commercialisation of its proprietary hydrometallurgical mineral processing technologies. These technologies have the potential to revolutionise the extraction processes for many base metals deposits by reducing costs, and hence enhancing operating margins, at the mine site.
MetaLeach® owns the intellectual property to two ambient temperature, ambient pressure, hydrometallurgical technologies, namely AmmLeach® (patents pending) and HyperLeach® (patents pending). These technologies are environmentally friendly, cost effective processes for the extraction of base metals from amenable ore deposits and concentrates allowing the production of high value products at the mine site (i.e. metal powder or sheets). These technologies were created as a result of the Company’s work at its Leon copper project in Argentina and subsequent research and development undertaken by the Company and its consultant Dr. Nicholas Welham.
Commercialisation of AmmLeach®
The following metals are particular targets for the AmmLeach® process:
- copper and copper/cobalt in carbonate and weathered oxide deposits;
- zinc (and cadmium) in mixed oxide deposits;
- nickel and cobalt in lateritic deposits;
- gold, silver and copper in leached porphyries;
- pre-treatment of gold ores with high cyanide-soluble-copper levels;
- polymetallic base metal deposits, especially uranium; and
- leaching of base metals from roaster concentrates.
Geographic diversification is offered as the countries with the most prospective geology for hosting high acid consuming copper (Cu) and zinc (Zn) oxides are Chile (Cu), Peru (Zn), Mexico (Cu & Zn), USA (Cu), Democratic Republic of the Congo (Cu, Cu/Co), Zambia (Cu, Cu/Co) and Australia (Cu).
Of these, the copper process has already been demonstrated at pilot plant scale for heap leaching, for which a more comprehensive description can be found below, and at bench scale for agitated leaching. The cobalt (or copper and cobalt oxide ore) process has been bench scale tested successfully for both heap and agitated leaching. Further development of the zinc process has led to a new solvent extraction process for zinc from ammoniacal solutions, for which patents are pending. This patent application is for the recovery of zinc from ores which do not require pre-treatment before ammoniacal leaching. A patent covering a process allowing selective leaching of zinc from sideritic zinc ores has also been applied for.
The nickel process is still under development but early trials on a wide variety of ores show promise. Because of the tailored pre-treatment step, almost any ore type is amenable to the AmmLeach® process. Thus far, it has been demonstrated on predominantly oxide ores but some sulphides have also been shown to leach after appropriate pre-treatment. This advance allows the treatment of mixed oxide-sulphide ores which are often present in the transition from weathered to un-weathered ore. As a project proceeds, the AmmLeach® process can be modified to cope with the changing mineralogy from oxide to sulphide without substantial capital expenditure.
Polymetallic ores can also be processed by AmmLeach®, with separation achieved using solvent extraction to separate metals and produce multiple revenue streams. The minimisation of ammonia transfer allows these metals to be recovered directly from their strip solution by precipitation, crystallisation or electrowinning.
The alkaline conditions used in the AmmLeach® process allow precious metals to be recovered from the base metal depleted heap using a secondary leach step. The heap can simply be washed to recover ammonia and subjected to standard alkaline cyanidation to recover gold and silver. Work is currently underway to incorporate precious metal recovery within the AmmLeach® process. Preliminary work on the leaching of cyanide consuming metals prior to precious metal leaching with cyanide looks highly promising.
Several multinational, major, intermediate and junior companies have assessed/are assessing the Company’s leaching technology, principally for copper, copper/cobalt and zinc. Although testwork and commercial discussions relating to these companies are subject to confidentiality agreements, included are companies which have significant interests in the African copper belt (Zambia and the DRC), Southern Africa, Australia, South America and North America. The DRC is becoming a focus as a result of advances made in using AmmLeach® to process copper/cobalt ores and, in turn, the country’s fabulous endowment in the two metals. A notable amount of activity also pertains to problem processing situations where MetaLeach®’s leaching technology could make a significant difference to the economic prospects.
The important initial stage to potential commercialisation involves amenability testing of third party ore samples. This testwork is carried out at the research and development facility at the University of Ballarat in Australia, supervised by our consultant Dr Nicholas Welham, and also at commercial laboratories. Industry recognition of the major commercial value of our technology has been shown by one company making an indicative, non-binding proposal to purchase the Company’s AmmLeach® technology, on an outright basis, for its global operations.
Potential project interests
The Company sees a significant opportunity to enhance the potential value of its technology by identifying and securing, where possible, equity interests in its own right in amenable deposits in exchange for the use of the technology. Many attractive opportunities in different regions of the world suitable for acquiring direct equity interests in copper and zinc properties and development projects have been identified.