The Backfilling Mode And Technology Based On Industrial Ecology

At the time when mining industry offers us raw materials, it inevitably deteriorates the natural environment. As the demand for minerals grows, environmental deterioration and waste discharge, induced by resource exploitation, have become serious global issues. Therefore, disposing of solid mining waste and effective backfilling of mined-out areas are two research subjects of pressing importance.From the viewpoint of industrial ecology, the most effective solution to mining-related environmental deterioration would be recycling the mining waste into exploitable secondary resources. The backfilling mode based on industrial ecology is to treat all the mining operations as a single system in which backfilling is viewed as an effective approach to turning the solid mining waste into resources so as to minimize its discharge. As a result, the environmental deterioration caused by mining waste is eliminated once for all. The backfilling mode dealt with in this paper features three basic elements, that is, (1) internal recycling technology; (2) profitability and (3) discharge of mining waste. The first element is a necessary condition, i.e.,the filling mode must be supported by low cost, highly effective and highly reliable backfilling technologies. Innovative backfilling technologies such as unclassified waste rock cemented filling, red mud consolidated filling and highly concentrated unclassified tailings squeezed transportation filling have been developed to satisfy this very requirement. The second element is a sufficient condition for achieving economic balance or even bringing new profits. The third element features the extent of turning waste into resources , which indicates that the filling mode controls the discharge of solid waste to a minimum or even to zero.In unclassified waste rock cemented backfilling, mining waste rock is used as filling aggregate. The filling ingredients are transported separately and then mixed through a new self-spraying technique, which can achieve optimum water content matching and result in desirablefilling performance. This technology not only simplifies the backfill system, cuts cement consumption and filling cost, but makes full use of the mining waste as well, enabling large scale continuous filling and disposing all the development waste underground. The model for optimum water content in a filling mixtures is : W=KcC +KgG, which fundamentally reveals the optimum water content in various filling ingredients. Under the condition of optimum water content, the model for uniaxial compressive strength of the cemented fill after 28 days is: R28=1.875+0.021C.The red mud consolidated backfill technology is to make use of the activity of red mud and the low grade requirement for mine fill. A mixture of activating agents with red mud can produce a consolidating agent which would fully satisfy the requirements for mine fill. Specimen blocks were made by mixing red mud consolidating agent and Grade 425" silicate, separately, in a ratio of 1:4, with unclassified tailings. After 28 days, the specimen block containing red mud consolidating agent exhibited a uniaxial compressive strength of 2.5MPa, 2.7 times that of the block containing cement. On the other hand, red mud consolidated backfill eradicates dewatering in slopes, exhibits good flowability and is favorable for filling to roof contact face. This technology offers an innovative alternative to the utilization of red mud which used to be activated by the traditional costly heating method. The new technology not only provides mines with a low cost consolidating agent, but also offers an approach to large scale use of red mud in a cheaper way.In the highly concentrated unclassified tailings squeezed transportation backfill technology, a squeezing transportation pump is installed underground. With the aid of gravity pressure, the highly concentrated unclassified tailings filling mixture is pressed and transported under a valveless condition. The squeezing pump mainly consists of a tee_fitting, a squeezing transportation cylinder...