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和硫化合物的清洁燃料的方法，研究了用流动式反应器在低温下对煤进行溶剂脱脂的方法。在350℃、10MPa条件下，用四氢化萘和煤衍生油、碳酚油、杂酚油对20种煤进行萃取。以四氢化萘为溶剂，在350℃下，烟煤的萃取物得率可达65 ~ 80%，萃取物在室温下分离为约25 ~ 40%的可溶部分（可溶）和约40%的室温析出固体部分（沉积）。Carbol油对低阶煤和烟煤均有较好的萃取效果，从褐煤（Morwell）到次烟煤（Miike）的萃取率均超过70%。从几种煤中提取的提取物几乎不含矿物质。以四氢化萘为溶剂时，煤中的大部分硫通过萃取保留在渣油中，而以碳油为溶剂时，大部分硫（包括黄铁矿硫）转移到可溶部分中。判断碳油中的极性化合物与黄铁矿硫发生反应，将其转化为可溶化合物。对含可溶性部分的溶剂进行循环利用，可以有效地提高沉积物的收率，并显著降低提取物中的矿物质含量。经过10次萃取后，矿床的矿物含量惊人地降至0.02wt%以下。因此，所提出的提取方法对于在相当温和的条件下从煤中生产大量清洁燃料是有效的。

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.