| Spontaneous combustion of sulfide ores is always affecting the safety in mining for a long time, and has become one of the major hazards in safe mining of sulfurous ore deposits. Nowdays, the sulfide ores spontaneous combustion mechanism, spontaneous ignition tendency, prevention and control methods were carefully analyzed by many scholars over the world. However, the problem was not solved ultimately because of the complexities of sulfide ores self-igniting process and the elusive of fire source of spontaneous combustion.With the rapid development of underground mine toward the depth, the high temperature of deeply mining is gradually aggravating the spontaneous combustion accident in mining process, and the ores self-ignition problem is more significant than before.So that research on the characterization of sulfide ores and the detecting technology of its fire sources have significant and realistic significance and applied value for us to understand the self-igniting process, estimate the present situation of ore piles, deduce the fire resources position and carry out the prevention action.On the basis of reviewing the previous papers in and aboard, the research methods combining the theoretical research, laboratory simulation, numerical analysis and field application were used to systematically and deeply analyze the fundamental theory, the heat-concentration ability of ore piles, the early stage fire law, the infrared detection methods of self-ignition resources, and the positioning technique of inner sources of ignition. The main work and achievements of the thesis are as follows:(1) On the basis of research findings, the fundamental natures of sulfide minerals and the ore self-ignite mechanism were synthetically analyzed, compared, summarized. And the interactive process of ores and oxygen was carefully discussed to provide dependable theoretical foundation and scientific proof for explore the sulfide ores self-ignition mechanism to perfect the sulfide ores self-ignition research achievements.(2) Seepage flow and diffusion flow were revealed to be major flow patterns of oxygen inside sulfide ore dumps. The thermal conductivity process of solid particles and clearance gas was considered as the thermal conductivity of sulfide ore dumps. Based on this, heat build-up process and poly-thermal heating conditions of sulfide ore dumps was derived; and then a systematic study on heat heap factors of sulfide ores was carried out using the combination of theoretical and experimental methods. It indicated that the main factors affecting ore self-heating were temperature, porosity, air leakage intensity, accumulated volume, oxygen concentration, water content and mineral particle size.(3) The modern testing and analytical techniques, such as TG/DSC analysis, solution content determination and Scanning Electron Microscopy were used for doing mineral samples, and the results were found that:â‘ The process of mineral heating release a large amount of heat;â‘¡Before and after oxidation, mineral samples surface becomes porous, loose, broken, accompanied by agglomeration.â‘¢In the ore, the content of some ions which are water-solubility Fe2++Fe3+ and SO42- were increased, especially the content of SO42-, and some ore increased tremendously. Studies have shown that the phenomena are the main features of the ore spontaneous combustion oxidation process.(4) Using the in-site experimental reactor as the best indicators of ore spontaneous combustion in the early stage, and discussed the characteristics of the temperature in the internal heap of ore and the impact on the surface temperature, the relationship between them was got,that indicted that the change of the surface temperature indirectly reflect the nature and extent of the oxidation of sulfide ores, and the change of temperature was closely quantify connected with every stage, through monitoring the change of surface temperature,the self-heating, spontaneous combustion within the ore heap was detected, and was suitable to be the indicator of ore spontaneous combustion in the early stage.(5) It was proposed that the methods of infrared thermography for detecting spontaneous fire of sulfide ores. The selection methods of infrared thermometer and mining thermal imager were analyzed, the factors that influence infrared detection of spontaneous fire of sulfide ores were studied using the IRI-1011 general-purpose thermal imager and put forward the corresponding corrective measures. The theoretical derivation and numerical simulation show that the existing thermal imager detecting of ore pile fire source within 10m is feasible. The detection process was designed, and several groups of optional parameters for the detection range and detection area adapted to IRI-1011 thermal imager were obtained. Also, it is proposed a fire detection method of dividing the large detection area into small ones layer by layer. Based on the study of the inverse problem of heat conduction, the method of spontaneous fire source location was discussed, and it is proposed a new fire source location method based on thermal imager with a large area scanning. |
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