Technical Development On Prediction And Forecast Of Spontaneous Combustion For Sulfide Ore Piles

Lots of sulfide ore mines exist among Chinese mining companies, spreading over nonferrous and chemical systems. It is estimated that 20% to 30% sulfide iron mines and 5% to 10% nonferrous or multi-metal mines have the hazard of spontaneous combustion. The fire caused by internal reasons in sulfide ore mines not only worsens the underground work environment, pollutes the ground air, affects the workers' health, but also wastes a lot of resources, and destroys the equipment, influences the normal task seriously, furthermore, it leads to huge life losses. Therefore, it is of great significance to research over the oxidation mechanism of sulfide ores and to predict and forecast the spontaneous combustion for sulfide ore dumps in time.The spontaneous combustion of sulfide ores is an extremely complex physicochemical course, which often changes from the static state under normal temperature to dynamic state of combustion. Based on referring to many research fruits on spontaneous combustion of sulfide ores and coal, study both in theories and experiments were made in-depth, such as the mechanism of oxidantion and self-heating, the distributing law of surface temperature, predicting and forecasting methods, and so on. The main study contents and conclusions of this paper are as follows:(1) The research production on the oxidation and spontaneous combustion of sulfide ores and coal were summarized by reading about 100 references, including the status quo of predicting and forecasting technology, comprehensive preventing and fathering measures. Moreover, the mechanism of spontaneous combustion was set forth in details.(2) The theories on the flow pattern of the air inside sulfide ore piles and porous medium dynamics, heat and mass transfer, combining with Darcy Law, continuity equation, conservation of mass and energy, were used to deduce a mathematical model, which was sufficient to describe the dynamic process of sufficient and necessary conditions for spontaneous combustion of sulfide ore piles. Based on the mathematical model of spontaneous combustion, the comprehensive model for predicting spontaneous combustion was built.(3) Combining with the boundary conditions on the spot, the powder and block sulfide ore piles were plotted out grid in 2D, moreover, the airflow and temperature field were simulated by applying CFD software FLUENT. Therefore, the transformation of its inner temperature can be known at some time.(4) In order to research the connection between the sensing data of the infrared thermometer and the actual surface temperature for various measuring distances, ore samples, and environmental conditions, the surface temperature of three different sulfide ore samples were measured by Raytek infrared thermometer and CENTER tangent thermometer simultaneously, and the measured values were analyzed in details, some important conclusions were gained, too.(5) Some theories about infrared radiation were introduced; Based on the study conclusions above, the choice principles of infrared measuring instrument for predicting and forecasting spontaneous combustion of sulfide ore dumps were summarized. These were used in actual piles and took effect well.(6) At last, some prospects over the building of oxidation and self-heating mathematic model, the research of numerical simulation software, and the developing of infrared measuring instrument, were made, which are of great significance for sulfide ores production.