Production of Clean Fuel by Solvent Skimming of Coal at Low Temperature

为了开发将煤转化为几乎不含矿物质和硫化物的清洁燃料的方法，利用流动式反应器对煤进行了低温溶剂脱脂试验。在350℃和10℃条件下，对20种煤进行了四氢呋喃和煤油、碳醇油和杂酚油的萃取。以四氢萘为溶剂时，烟煤的萃取率在350 Mpa时达到65%~80%，并在室温下分离出约25%~40%的可溶组分(可溶)和约40%的固相(沉积)。焦油对低级煤和烟煤均有较好的萃取效果，从褐煤Morwell到亚烟煤Miike的萃取率均超过70%，几种煤的萃取物几乎不含矿物质。以四氢呋喃为溶剂时，煤中大部分硫通过萃取保留在残渣中，而使用碳化油时，包括黄铁矿硫在内的大部分硫被转移到可溶组分中。Carbol油中的极性化合物被判断为与黄铁矿硫反应，将其转化为可溶化合物。回收含有可溶部分的溶剂可有效地提高沉淀物的产率，并显著降低萃取物中的矿物质含量。经过10个循环的提取后，矿床的矿物质含量惊人地降低到0.02wt%以下。结果表明，该方法可以在较温和的条件下，从煤中大量生产清洁燃料。

To develop methods for converting the coals to the clean fuels which are almost free from mineral matter and sulfur compounds, Solvent skimming of coal at low temperature using a flow-type reactor was examined. Twenty kinds of coals were subjected to the extraction by tetralin and coal derived oils, carbol oil and creosote oil, at 350℃ and 10MPa.The extract yield reached 65 to 80% for bituminous coals at 350℃ when tetralin was used as the solvent, and the extract was separated into about 25 to 40% of soluble fraction at room temperature (soluble) and about 40% of solid precipitated at room temperature (deposit). Carbol oil was effective to extract low rank coals as well as bituminous coals and the extraction yield exceeded 70% for the coals ranging from a brown coal, Morwell, to a sub bituminous coal, Miike.The extracts obtained from several coals were found to be almost free from mineral matters. Most of sulfur in coal was retained in the residue through the extraction when tetralin was used as the solvent, whereas most of sulfur including pyritic sulfur was transferred into the soluble fraction when the carbol oil was used. Polar compounds in the carbol oil were judged to react with the pyritic sulfur to convert it into a soluble compound. Recycling the solvent containing the soluble fraction was found to be effective to increase the yield of deposit and to decrease the mineral matter content in the extract dramatically. The mineral matter content of the deposit was surprisingly reduced below 0.02wt% after 10 extraction cycles. Thus, the validity of the proposed extraction method was presented for producing a large amount of clean fuels from coals under rather mild conditions.