Membrane‐based technology for clean‐up of thiocyanate

(SCN‐) from gold mining tailings water Polymer inclusion membranes (PIMs)

Continuous process

Economical manufacturing process using inexpensive commercial materials

Robust and flexible membranes withstand industrial processing

Commercial Engagement Services

Publications Y.Y.N. Bonggotgetsakul, R.W. Cattrall, S.D. Kolev, The preparation of a gold nanoparticle monolayer on the surface of a polymer inclusion membrane using EDTA as the reducing agent, Journal of Membrane Science 379 (2011) 322-329 Y. Cho, C. X, R.W. Cattrall, S.D. Kolev, A polymer inclusion membrane for extracting thiocyanate from weakly alkaline solutions, Journal of Membrane Science 367 (2011) 85-90

Thiocyanate (SCN‐) is a major constituent in waster water produced by many industrial processes. Some industrial waste water (effluent), such as those from the steel industry, petrochemical industry and water

Background

produced through the gasification of coal, often contains a significant concentration of SCN‐. SCN‐ is a common cyanide reaction product of industrial effluent where cyanide (CN‐) is used.

Case Study Problems

Case 1 . Decrease gold recovery

Gold mines use a blend of tailings and fresh water in the flotation of the crushed gold (Au) ore in order to reduce overall water consumption (see Fig. 1)

SCN‐ in the water blend reduces the efficiency of the flotation of gold ore by decreasing the hydrophobicity of the sulfidic particles containing gold which leads to the undesired effect of a decrease in overall gold recovery - in some cases up to 6% depending on the chemical composition of the gold ore.

Fig. 1. Schematic of the gold extraction process.

Limitations of current methods

The ASTER® Process is based on the biodegradation of SCN- and is expensive, energy demanding due to the maintenance of an ambient temperature, prone to instability and is difficult to incorporate into a continuous process. Chemical oxidation is also expensive and uses corrosive, toxic materials such as chloride, ozone and hypochlorite are all chemicals that pose considerable environmental and health concerns.

Reverse osmosis is also energy demanding and thus expensive. There is a need for an environmentally friendly, inexpensive in terms of both equipment and running costs and more efficient technology for SCN- removal from gold mining tailings water which can be implemented as a continuous process.

Case 2 . SCN- groundwater contamination

SCN- is toxic to aquatic organisms. Groundwater around tailings dams contains high concentration of SCN-, in one instance an Australian gold mine was found to have SCN- up to ~ 200 mg/L.

To prevent contamination of proximal rivers, lakes etc, expensive pump systems are required to dislocate the bore/groundwater to the tailings dams . Upon mine closures, the dislocation process is required for 10-20 years and in the case of one particular Australian gold mine, the groundwater will require detoxification from SCN- at a rate of 20-30 ML per annum.

Commercial Engagement Services

The University of Melbourne is one of Australia’s foremost research and teaching institutions, with strengths in human and veterinary medicines, fundamental science and advanced materials science, engineering, information and communications sciences, animal and plant biotechnology. The University has a very successful record of technology commercialisation and transfer through wide research linkages, licensing arrangements and start‐up companies.

In addition to his work on membrane separation, University of Melbourne School of Chemistry Professor and Lloyd Smith Medal recipient Spas Kolev has a focus on developing flow analytical techniques for on-line environmental and industrial monitoring and has a concern for Phytoremediation of contaminated soil and biosolids by metal hyperaccummulating plants.

New Technology

Opportunity/Partnering

Commercial Engagement Services

To explore this license or collaboration opportunity, please contact:

Dr Michael Jorgensen PhD, Senior Business Development Manager

UoM Commercial Ltd 205-211 Grattan Street, Carlton VIC 3053 Australia phone: : +61 3 9035 9602 email: michael.jorgensen@unimelb.edu.au www.commercial.unimelb.edu.au

The University of Melbourne is one of Australia’s foremost research and teaching institutions, with strengths in engineering, information and communications sciences, animal and plant biotechnology, human and veterinary medicines, fundamental science and advanced materials science.

The University has a world-class research team in the field of optical data transmission.

The University has a very successful record of technology commercialisation and transfer through wide research linkages, licensing arrangements and start-up companies.

Inventors

Intellectual Property

Polymer inclusion membranes (PIMs) are a relatively new type of self-supporting liquid membrane that are designed to extract ions or neutral molecules from solutions. PIMs typically incorporate a base polymer (usually PVC or cellulose triacetate), an inexpensive commercially available liquid extractant, which acts a carrier, and an

optional plasticiser or modifier. Very often the extractant acts as a plasticiser. Extractants for anions (eg. SCN-) are often tertiary amines (Alamine 336) or quaternary ammonium salts (Aliquat 336, a mixture of quaternary ammonium chlorides).

PIMs are homogenous, optically transparent and mechanically strong.

UoM is seeking partners to development and commercially exploit the technology.

Emeritus Professor Robert Cattrall holds an honorary position in the School of Chemistry and his interests involve the study and application of membranes for separation of metals particularly in hydrometallurgy. Ms. Yongsoo Cho is a PhD student in the School of Chemistry at the University of Melbourne.

Fig. 2. Photograph of a typical PIM.

Benefits

Since PIMs do not incorporate solvents and offer better selectivity and enrichment factors than conventional solvent extraction, they are deemed to be environmentally friendly. PIMs allow for continuous separation since the target chemical species is extracted across and isolated. PIMs are highly selective and can be fine tuned by modifying the membrane composition.

The inherently flexible and robust characteristics of PIMs allow for the incorporation into industrial flat sheet & hollow fibre separation modules. In essence, PIMs are inexpensive and easy to manufacture and to incorporate into existing industrial set-ups and as such are able to quickly and efficiently remove SCN- from tailings solutions.

Fig. 3. Three unit SCN- separation unit.

A PCT application PCT/AU2011/001034 entitled “Process for treating thiocyanate containing aqueous solution” was filed 22th August 2011.