A novel coal cleaning with pretreatment in methanol

为了提高煤中矿物夹杂物的析出率和磨矿能量的利用率，对甲醇预处理煤进行了探索。用甲醇在室温下对14种煤进行了所需时间的处理。甲醇处理后，所有的煤都倾向于容易研磨。处理后的煤颗粒的抗压强度降低到母煤的一半左右。处理后的煤的可磨性明显高于原煤。例如，处理后的扬松煤、埃比尼茨雷煤、大同煤、纽兰煤和拉马格雷煤的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%和从2.6%增加到6.4%。甲醇预处理对煤的可磨性的改善效果与煤种有关，SEM观察表明，预处理使煤颗粒中产生了大量裂纹。CC-SEM分析揭示了甲醇预处理对矿物选择性还原的可能性。对磨煤样进行了离心分离。预处理提高了有机质的回收率和矿物质的去除率。以阳松煤为例，在灰分降低85%、90%和95%的条件下，未处理煤的有机物回收率分别为78%、59%和32%，处理煤的有机物回收率分别为92%、80%和53%。在1600℃以下考察了Ca化合物与煤焦的反应。CaO在950℃左右开始与煤焦发生反应，并对煤焦的石墨化有较强的催化作用，在1600℃左右主要生成石墨碳。

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℃.