Arsenic and antimony immobilization from mineral processing solutions and waste waters

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The increased extraction of mineral resources and mining activities have added pressure on the environment, therefore it is imperative that proper processes for water/waste management are developed. Arsenic and antimony are among the toxic elements which are usually released into the environment from mining activities. The mining operations at the Giant Mine gold mine in the Northwest Territories, which was operated from 1948 to 2004, have created 237,000 tonnes of arsenic trioxide dust. Arsenic trioxide is soluble in water and has contaminated soil and buildings in the surrounding area. In another case, arsenic concentrations of up 100 mg/L were detected in the tailing porewater (underground water) of Campbell Mine, Balmertown, ON. This arsenic level is 10,000 times higher than the maximum acceptable arsenic level by Canadian drinking water quality standard, which is 0.010 mg/L. As high grade and clean deposits are becoming more difficult to find, there is a need for the development of processes to extract complex arsenic and antimony-containing orebodies, minerals and metals in a safer, more environmentally sustainable manner. This is essential for the continued financial sustainability of the Canadian mining industry, the largest employer of the Canadian economy. Processing of complex orebodies is not possible without further development of robust solutions for the management of toxic elements. There is a need for development of processes that can immobilize (precipitate) the toxic elements as safe, non-toxic and stable compounds. In particular, the precipitates must have long term environmental stability for thousands of years. The applicant proposes to establish a research program to study the arsenic and antimony immobilization processes. The long-term goals of this research program are to develop a comprehensive understanding of the chemistry of the two elements in the mining processes, and the long-term stability of the arsenic and antimony-containing precipitates in the environment. During the next five years, i.e. short-term objectives, it is proposed to generate a solid knowledge of the arsenic and antimony oxidation mechanisms, investigate the feasibility of arsenic immobilization through sustainable bio-oxidation and bio-precipitation processes, develop a reliable protocol for long-term stability assessment of arsenic and antimony precipitates, and generate a global list of most stable arsenic and antimony compounds/precipitates, to be used as a reference document for process selection/development by the mining industry. It is expected that the knowledge, and HQP developed through this research program will be highly sought after by the Canadian mining industry. Two Ph.D. students and two Master's students will be trained through the first 5-year round of this research program.