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酸化处理对焦煤萃取性能的影响

Effect of acidification treatment on the extraction performance of coking coal

  • 摘要: 为了研究煤中矿物质脱出对溶剂萃取行为的影响机制,采用不同浓度的四氢呋喃(THF)溶剂对盐酸(HCl)和氢氟酸(HF)酸化处理前后的焦煤进行萃取试验,借助于常规煤质分析和气相色谱-质谱(GC-MS)测试方法,分析了煤样脱矿物前后THF萃取率和萃取物成分的差异,探讨溶剂浓度、萃取时间、温度、矿物质对其影响机制。结果表明:①煤样经酸化处理后,灰分产率高达97.3%,含量显著降低,固定碳含量增加21%,挥发分含量相对增加,而水分含量基本不变;C、H元素含量下降,O、N、S元素含量增加,其中C、O元素含量变化较明显;②酸化处理后的煤样萃取率显著增大,但随着THF浓度的增加,萃取率增幅呈现不断减小的趋势;同一条件下达到同样的萃取效果,酸化煤萃取时间较原煤快1.25~5.00倍;酸化处理放大了温度对萃取率的影响效应,使得35 ℃的萃取优势更为显著。③原煤萃取物中杂原子化合物相对含量占比最高,而酸化煤萃取物中以脂肪烃为主,其中直链烃含量随着THF浓度的增大不断增加,最高可占总含量的91.92%,碳原子数主要集中于C15~C22,但萃取物种类数显著少于原煤。总体而言,酸化处理可有效提高THF的萃取能力,大幅度缩短萃取时间,且提高了对煤中高碳烷烃的萃取能力。此外,尽管萃取过程中水不占据主导地位,但在一定程度上也会影响THF的萃取能力,使得低浓度的THF溶剂萃取能力优于THF纯溶剂。

     

    Abstract: In order to study the influence mechanism of minerals removal from coal on solvent extraction behavior, different concentrations of tetrahydrofuran (THF) solvents were used to extract coking coal before and after acidification with hydrochloric acid (HCl) and hydrofluoric acid (HF). With the help of conventional coal quality analysis and GC-MS test methods, the differences of THF extraction rate and extract composition before and after demineralization of coal samples were analyzed, and the influence mechanism of solvent concentration, extraction time, temperature and minerals was discussed. The results show that: ①After acidification, the ash yield of coal sample reaches 97.3%, the content decreases significantly, the fixed carbon content increases by 21%, the volatile content increases relatively, but the moisture content remains basically unchanged; The contents of C and H decrease, while the contents of O, N and S increase, among which the contents of C and O change significantly. ②The extraction rate of coal samples after acidification increase significantly, but with the increase of THF concentration, the increase of extraction rate show a decreasing trend. The same extraction effect is achieved under the same conditions, and the extraction time of acidified coal is 1.25~5 times faster than that of raw coal; Acidification treatment enlarges the effect of temperature on extraction rate, which makes the extraction advantage at 35 ℃ more obvious. ③The relative content of heteroatom compounds in raw coal extracts is the highest, while aliphatic hydrocarbons are the main components in acidified coal extracts, among which the content of straight chain hydrocarbons increases with the increase of THF concentration, accounting for 91.92% of the total content. The number of carbon atoms is mainly concentrated in C15~C22, but the number of extracted species is significantly less than that of raw coal. Generally speaking, acidification treatment can effectively improve the extraction capacity of THF, greatly shorten the extraction time, and improve the extraction capacity of high carbon alkanes in coal. In addition, although water does not dominate the extraction process, it will also affect the extraction ability of THF to a certain extent, making the extraction ability of low concentration THF solvent better than that of pure THF solvent.

     

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