A novel coal cleaning with pretreatment in methanol

为了提高矿物包裹体的析出率，提高磨矿能的利用率，对煤的甲醇预处理进行了探索。用甲醇在室温下对14种煤进行了所需时间的处理。经甲醇处理后，所有煤都容易磨碎。处理后的煤颗粒抗压强度降至母煤的一半左右。处理后煤的可磨性明显高于原煤。例如，Yang-song煤、Ebenezre煤、大同煤、Newlands煤和Ramagundum煤经过处理后，0.150 mm以下颗粒的累积重量百分比分别从20.8%提高到50.3%、44.4%提高到87%、32.6提高到42.6%、27%提高到48.8%、2.6提高到6.4%。甲醇预处理对可磨性的影响与煤的类型有关。扫描电镜观察表明，预处理后的煤颗粒中形成了许多裂纹。CC-SEM分析揭示了甲醇预处理有利化作用选择性还原矿物的可能性。对地煤样品进行了离心分离。预处理提高了有机质回收率和矿物还原率。以阳松煤为例，在灰分减少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%。为了减少有机硫的排放，将钙化合物加载到预处理煤中。在高达1600℃的温度下，研究了Ca化合物与煤焦的反应。CaO在低至950℃时开始与煤焦反应，对煤焦石墨化有较强的催化作用，在1600℃时主要形成石墨碳。

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℃.