| Sulfide ore spontaneous combustion accident is a major underlying danger in developing metal mines. The fire accident will trigger a series of safety and environmental issues, such as underground working environment deterioration, ground air pollution, workers' safety problems finally leading to the huge waste of mineral resources. After sulfide ore is mined, specific surface will increase sharply, which results in increased contact area of ore and moist air. And this is more prone to oxidation and gives off heat. When the reaction heat is greater than the loss heat around, the temperature of the ore will continue to rise, until reaching the spontaneous combustion point, ultimately causing spontaneous combustion fire. Therefore, the research on the mechanism of sulfide ore spontaneous combustion, the influential factors, testing methods and monitoring measures are very necessary and urgent.However, because sulfide ore spontaneous combustion is a complex process, which makes the relevant achievements on spontaneous combustion of sulfide ores less rich. So on the basis of previous researches and references to a large number of papers, this paper tries to carry out the following researches:(1) This study expounds and analyzes the mechanism of sulfide ores and introduces the identification method and prevention precautions of spontaneous combustion tendency of sulfide ores.(2) The present paper studies all the possible factors that could cause spontaneous combustion of sulfide ores by Fault Tree Analysis. Taking the relevant influential factors in the microbial mechanism into consideration, this paper calculates the fault tree's minimum cut set and minimum radius set and analyzes the structure importance of the various factors. The results show that some important factors change in the process, for example, oxidation weight gain rate of X9, hydroscopicity of X10 and environment humidity of X11 increase. All these changes should be considered and analyzed in the prevention of ore spontaneous combustion accident.(3) By using the method of comprehensive laboratory test, this paper conducts an experiment on the spontaneous combustion tendency of a copper mine in Xinjiang. The main works are listed as follows: chemical composition analysis, mineralogical analysis, test of self-heating point, spontaneous combustion point and absorption of oxygen speed, oxidized ore sample test. The results show that(1)the average sulfur content in Ashele copper deposits is 34.9%, reaching a relatively high level;(2)metallic minerals are featured by pyrite, chalcopyrite and sphalerite in massive and cataclastic structures;(3)the contents of Fe2+?Fe3+?SO42- keep at a low level in spite of the time;(4)Oxidizing properties test on ores in normal temperature shows an inactive reaction, however, after the pre-oxidation, oxidation activity improves a little.(4) Numerical simulation analysis on the temperature field and airflow field of ore stockpile by Fluent is carried out. Based on the heat transfer model of ore stockpile, this paper simulates the situation of temperature field and airflow field of ore stockpile. In the end, the distributions of temperature field and airflow field of ore stockpile in different time nodes are obtained. The temperature distribution and airflow distribution of sulfide ore in the initial stage and after five days and ten days are analyzed and temperature characteristics under the condition of wind flow of 0m/s?0.2m/s and 0.4m/s are examined. |
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