Impacts de recouvrements de residus organiques sur des residus miners reactifs Impacts of organic waste linear covers on reactive wastes

摘要

Nowadays, mining waste is an important environmental problem, especially that involving acid drainage. Such conditions often occur following the exploitation of gold, copper, silver, zinc, lead and other ores which are always associated with sulphate components. In the presence of oxygen, the sulphide minerals may form sulphuric acid and hence the drainage from such mines may have pH values as low as 2 to 3. One of the solutions to this problem is to prevent any interaction between oxygen in the air and the mine waste by the use of a liner cover. Organic waste, such as from paper recycling and wood mills, has the potential to reduce oxygen diffusion when used as a liner cover. Research into the efficiency of these materials has been undertaken particularly in universities in Canada. Among the organic materials indicated as potential liner barriers are de-inking residues and forest/wood mill waste. The de-inking residues originate from the paper recycling industry where about 30% is waste composed essentially of secondary cellulose, calcite and metakaolinite. The forest/wood mill waste comprises leaves, barks, branches and wood shavings. The barks are rich in lignine and the other components in primary cellulose. Research into the use of these materials as an oxygen barrier and soil fertilizer has been reported. When the organic liner cover is in contact with DMA mining waste, different types of reaction can occur depending on the initial composition of the waste and the length of time for which it is exposed. This paper presents research into the interactions between both potential liner materials and acidic mine waste. In addition, it examines the possible secondary products that may be formed by the chemical reactions, in order to understand both the nature of such products and their potential environmental impact.