September 2003

Development of Ultra Fine Cyclone Classification System

Since taking over the manufacture of the Warman Cyclosizer in 2001, and with the trend in many mining processes towards finer grind sizes, we have been asked on many occasions for a finer classification size than the 11 to 12µm separation achieved in the C5 cyclone of the Cyclosizer. This has led to the prototype development of the ULTRASIZER, which is based on the Cyclosizer concept but adds a separate classification step at 6 to 7µm. The advantage of this system, as with the Cyclosizer, is that it gives the fractions back for assay or liberation studies so important in identifying metallurgical performance.

The cyclone is operated at higher pressures, which along with modifications to the cyclone proper, allows for the separation. Finer cuts than the 6 to 7µm are theoretically feasible but the operating pressures required increase exponentially and become the limiting factor.

The sample treatment, as with the Cyclosizer, is limited to between 30 to 50 grams per pass. The sample is screened at between 75 and 38µm to remove coarse particles and then run through the ULTRASIZER. The overflow fraction at minus 6 to 7µm, the so called C6 fraction is collected in the system and can be recovered by settling or flocculation. The plus 6 to 7µm fraction is recovered and passed through the Cyclosizer in the usual manner.

The classification in the ULTRASIZER is specific gravity dependent in the same manner as the Cyclosizer and so the 6 to 7µm sizes quoted for quartz become 2 to 3µm for gold, making the information that can be gleaned from modern particle liberation techniques a valuable tool in predicting and optimizing process performance.

In conjunction with the development of the ULTRASIZER we have also developed a cyclone classification system based on either a Krebs 1" cyclone or a modified Cyclosizer cyclone to carry out a less scientific split at 6 to 7µm to produce larger quantities of product. This incorporates a cyclone mounted over a 200-litre drum fitted with an agitator (see picture)

Unisearch/Metcon "Solvent Assisted Elution" or SAE Process

Metcon have entered into agreement with Unisearch (the commercial arm of the University of New South Wales) to undertake development work on a novel process for the selective recovery of gold, copper and cyanide from a loaded resin. The work is a development of previous work carried out using resins to load copper cyanide and gold cyanide complexes from cyanide leach solutions. It has been the subject of both laboratory continuous pilot scale resin in pulp loading tests and a full scale resin stripping plant trial of heap leach solutions in a preceding generation process.

The technique applies to ores that have high cyanide consumption through dissolution of copper that make conventional CIP inefficient and/or uneconomic. The search for such a process has been on for many years now and is the topic of a number of research papers. However Metcon believes the SAE process is well advanced on other options as it is now based on second generation techniques. Most of the other processes have not been tried on either a continuous basis or on a full scale basis. The lessons learnt on the first trials and the obstacles encountered have contributed to the process, which is the subject of a patent application. The patent itself applies only to the core process while the work at Metcon is directed at proving the complete package so that it can be retrofitted to existing plant or engineered as part of a feasibility study.

Metcon is interested in contacting anyone who may have application for the process by emailing your enquiry to metconlabs@bigpond.com. Advantages of the process are:

• better than 70% of the cyanide is recovered for recycling in an alkaline solution with no acidification step (such as in the AVR process)
• copper is recovered in saleable form via the SART process
• gold is recovered by electrowinning

May 2001

Ammtec Purchase Metcon Laboratories

 Metcon Laboratories have been purchased by Ammtec Limited of Perth in a negotiated and friendly takeover. As an expression of Ammtec’s confidence in the current management, all  Metcon staff have been retained.

The acquisition is seen as a good situation for both parties. From Metcon’s point of view the merger provides access to Ammtec’s larger technical and equipment resource base.  For Ammtec, a point of presence now exists on the east coast of the country, a truly unique situation in this segment of the minerals industry. As both companies are in the same business and have a similar background and method of operation, we believe the mining industry now has access to a superior metallurgical consulting and testing service.

 Because we are now part of the Ammtec group it does not mean that we will no longer compete with them for work. Ammtec have purposely left the Metcon Laboratories operation intact and, although there is agreement of support once a job has been successfully won, both parties have agreed to pursue work independently. By way of example, Metcon recently missed out on a job to Ammtec, even though ours was the lower quote, mainly because the particular client felt more comfortable with the metallurgist from Ammtec with whom he had dealt before. This  situation could have just as easily worked in reverse.