A novel coal cleaning with pretreatment in methanol

为了提高矿物包裹体的释放率和磨矿能量的利用效率，对煤进行了甲醇预处理。在室温下用甲醇对14种煤进行了所需时间的处理。经过甲醇处理后，所有的煤都容易被粉碎。处理后的煤粒抗压强度降低到原煤的一半左右。处理后的煤的可磨性明显高于原煤。例如，杨松煤、埃比尼茨尔煤、大同煤、纽兰煤和拉马贡杜姆煤处理后，0.150 mm以下颗粒的累积重量百分比分别从20.8%增加到50.3%，从44.4%增加到87%，从32.6%增加到42.6%，从27%增加到48.8%，从2.6%增加到6.4%。煤种不同，甲醇处理对煤粉可磨性的影响也不同。扫描电子显微镜观察发现，甲醇处理后的煤粒中形成了大量的裂纹。CC-SEM分析表明，在甲醇中进行前处理可以实现矿物的选择性还原。对磨碎的煤样进行了离心分离。经处理后，有机质回收率和矿物质减少量均有所提高。以杨松煤为例，在灰分降低85%、90%和95%的情况下，未处理煤的有机质回收率分别为78%、59%和32%，处理煤的有机质回收率分别为92%、80%和53%。在1600℃的温度下研究了钙化合物与煤焦的反应。CaO在950℃时开始与煤焦反应，在1600℃时，CaO对煤焦的石墨化有很强的催化作用，主要生成石墨炭。

In order to improve the liberation of mineral inclusions and the efficiency of grinding energy utilization, pretreatment of coal by methanol was explored. Fourteen kinds of coals were treated with methanol at room temperature for the desired time. After methanol treatment, all the coals tended to be easily ground. The compressive strength of the treated coal particle was reduced to about a half of that of parent coal. The grindability of the treated coal was quite higher than that of raw coal. For example, the cumulative weight percent of the particles under 0.150 mm were increased from 20.8 to 50.3%, from 44.4 to 87%, from 32.6 to 42.6%, from 27 to 48.8% and from 2.6 to 6.4% after treatment, respectively, for Yang-song coal, Ebenezre coal, Datong coal, Newlands coal and Ramagundum coal. The effectiveness of the methanol pretreatment on the grindability depended on coal type.SEM obseavation revealed that many cracks were formed in coal particle by the pretreatment. CC-SEM analysis revealed the possibility of selective mineral reduction by the benification with pretreatment in methanol. A centrifugal separation was conducted for ground coal sample. Organic matter recovery and mineral matter reduction were improved by the pretreatment. For example, in the case of Yang-song coal, the organic matter recovery is 78, 59 and 32% for untreated coal and 92, 80 and 53% for treated coal at ash reductions of 85, 90 and 95%, respectively.In order to reduce the emission of organic sulfur, calcium compound is loaded to the pretreated coal. Reactions of Ca compounds with coal char were examined at temperatures up to 1600℃. CaO started to react with coal char at a temperature as low as 950℃ and exerted a strong catalytic effect on the graphitization of coal char, mainly forming the graphitic carbon at 1600℃.