Effects of grain boundary fracturing on particle size distributions and grade variations in comminuted ores

• Main Authors: Chin-Wen Lai, 賴錦文
• Other Authors: Shaw-Bing Wen
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/hr2289

博士 === 國立成功大學 === 資源工程學系碩博士班 === 91 === 　　Grain boundary fracturing, proposed by Gaudin in 1939 in his textbook “Principles of mineral dressing”, is a major influencing factor that makes the abnormal distribution in the particle size and the grade of comminuted ores. But there is no other quantified research presented for about 60 years since then. This study is based on the quantified factor, intergranular fracturing factor P, in comminuted ores and uses the exposure model and the liberation model to infer the quantified values of particle size distribution and grade distribution of crushed ores. By the experimental results, the accuracy of the quantified calculation model based on the models is proved. 　　This study is based on the exposure model and liberation model of Hsih and Wen (1995-1998) that are utilized to study the abnormal distribution of particle size distributoin and grade variation in comminuted ores. Experiment is applied to put to the proof of the inferred model. The experimental procedure is conducted by jaw crushing and the comminuted ores sieved to gain the particle size distribution and analyzes the grade distribution in each size interval. The components and grain size distribution of samples are also obtained by experimental analysis. With different intergranular fracturing factors put into the model to calculate the grade variation of valuables in comminuted ores, the results of right or wrong for the model inference is obtained. Samples utilized to test are arc steel slag, waste SiC grinding stone and talc schist that are recycling material in Taiwan. 　　Particle size distribution, grain size distribution and grade variation in each size interval, obtained from experimental and calculation, are utilized in the formulae of grade variations of the exposure model to compute the variation of grade in valuables of slag, grinding stone and talc schist. It’s found that in a specific value of intergranular fracturing factor the calculated results of formulae are matched well with experimental results. The inferred model in this study puts to proof by the good coincidence with the experimental data. After the calculation, the intergranular fracturing factor, P, in slag is 0.30, in grinding stone is 0.35 and in talc schist is 0.70. Different closed sets at a jaw crusher make the variations of grade in valuables and the comparatively better condition of comminution and liberation can be chosen. 　　This research derives a useful calculational model to evaluate the variations of grade at different size ranges in comminuted ores. The evaluated method applied in the quality control of comminuted products promotes the efficiency of comminution procedure. It indeed improves the numerous and jumbled calculation works conducted by other researchers. The grade variation model is proved to be simple and practical and it is also the greatest contribution of this study.