煤基费托合成油的催化氧化及对贫煤的浮选机理研究

Study on Catalytic Oxidation of Coal-based Fischer-Tropsch Synthetic Oil and Flotation Mechanism with Lean Coal

为提升煤基费托合成油(CBFTSO)的附加值并拓宽其应用领域,以环烷酸锰为催化剂,采用催化氧化法对其开展了改性研究。在此基础上,以山西某洗煤厂的浮选入料为研究对象,通过浮选试验确定了适宜的氧化反应条件,并借助气相色谱-质谱联用分析(GC-MS)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和接触角测试揭示了OCBFTSO(最佳氧化条件下的产物)与煤的作用机理。结果表明,CBFTSO的最佳氧化条件为氧化温度120℃、催化剂浓度0.1%、氧化时间12 h;在OCBFTSO、起泡剂(杂醇)用量均为50 g/t时,可获得精煤产率86.59%、精煤灰分8.64%的分选指标,与CBFTSO作捕收剂时相比,精煤产率提高了约2个百分点,精煤灰分降低了约1个百分点。机理分析结果表明,CBFTSO中的正癸烷及4-叠氮庚烷通过反应(链引发等)使OCBFTSO中出现极性基(酮基),该基团会与煤表面的C-O和O-C=O基团结合,提升煤表面的疏水性;使用OCBFTSO降低了精煤中高岭石和石英的含量,故具有良好的浮选选择性。

In order to improve the added value of coal-based Fischer-Tropsch synthetic oil(CBFTSO)and broaden its application field,the modification study of CBFTSO was carried out by catalytic oxidation method with manganese naphthenate as catalyst.On this basis,the flotation feed of a coal washing plant in Shanxi Province was taken as the research object,and the suitable oxidation reaction conditions were determined by flotation test.The interaction mechanism between OCBFTSO(the product under the optimal oxidation condition)and coal was revealed by gas chromatography-mass spectrometry(GC-MS),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and contact angle test.The results show that the optimum oxidation conditions of CBFTSO are oxidation temperature 120℃,catalyst concentration 0.1%and oxidation time 12 h.When the dosage of OCBFTSO and foaming agent(fusel)is 50 g/t,the separation index of concentrated coal yield 86.59%and concentrated coal ash 8.64%can be obtained.Compared with CBFTSO as collector,the concentrated coal yield is increased by about 2 percentage points,and the concentrated coal ash is reduced by about 1 percentage point.The mechanism analysis results show that the n-decane and 4-azidoheptane in CBFTSO make the polar group(ketone group)appear in OCBFTSO through reaction(chain initiation,etc),which will combine with the C—O and O—CO groups on the coal surface to improve the hydrophobicity of the coal surface.The use of OCBFTSO reduces the content of kaolinite and quartz in concentrated coal,so it has good flotation selectivity.