The purification of sulphate polluted water

摘要

Over the last couple of years, Mintek have been involved in the treatment of various waste streams by recovering different minerals economically. Waste streams, like acid mine drainage, however provide the biggest challenge as it consist of no economic recoverable elements. Mintek is developing a solution to this problem. It entails the precipitation of metal hydroxides, calcium sulphate and calcium carbonate. The key to the viability of the new technology lies in the correct use, regeneration and recycling of A1(OH)_3 used to precipitate the ettringite. The water produced by this process is suitable for disposal to watercourses or for agricultural, domestic or industrial consumption. The salts are converted to solid hydroxides, gypsum and calcium carbonate. The technology has been tested on several different waters in pilot plants campaigns. Results obtained indicate that potable water can be produced (containing less than 200 mg/1 sulphate and no heavy metals) as long as the monovalent ions (Na~+, Cl~-, etc.) are within limits. An overview of the process is presented, along with the results obtained in the pilot-plant tests on specific samples of polluted mine drainage.