| Xinqiao Mining Corporation Ltd (shortly, "XMC") of Tongling Chemical Industry Group is a large copper-sulfur mine with the exploration of open-pit and underground mining. The output of tailings with great viscosity is 3.134 million tons every year. The sulfur content of the tailings varies between 3 and 10%. In order to deal with the serious problem of disposing of the tailings, the comprehensive technical treatment means of the crude tailings in XMC were discussed, based on detailed researches including field research, literature searches, laboratory testing, pilot tests and process comparison. Major conclusions are summarized as follows:(1) Crude tailings in XMC are not qualified aggregates because of its fine particle size, poor permeability and high sulphur content. Fine size and poor permeability make the crude tailings are difficultly mixed and transported by gravity, and high sulfur content would easily damage backfill body due to its expansion function with cement. Fortunately, laboratorial tests show that drawbacks mentioned above could be elimated by addition of fly ash. The optimal dosage of cement, fly ash and crude tailings 1:2:6 in weight.(2) The tap water can be replaced by mineral separation wastewater. In this way, it is possible to recycle industrial water.(3) Transportation schemes of crude tailings with high viscosity and sulfur content were proposed. A backfill filling preparation scheme which can meet the requirement for both the original western underground mining and the future eastern underground extraction tansimted from open-pit was also suggested.(4) Scientifical evaluation of original backfill site and comparision between a new site and improvement of old site indicated that a new bckfill site would be identical to the long-term planning of XMC.(5) Possible backfill site position was recommended by comprehensive judgement using AHP method and the fuzzy mathematics. Such influencing factors as total infrastructure expenditure, operation costs, ratio of pipe length to backfill depth, and difficulties of daily management and land acquisition were taken into account in jugdement. Neccessary measures were also proposed in case of bakfill slurry could not transport into remote area by gravity flow. (6) A model about computation of critical grade at which crude tailing can be recycled was constructed. Repayment of capital loan is also considered in the model. Case study gave that the critical grade estimated was about 5%.(7)The disposing method of crude tailings beyond requirement of backfill in XMC was provided, that is dry depositing it at a temporary site near a gold concentrator.
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