Study On Shale Oil Recovery From Oil Shale Sludge

Oil shale sludge is a high oil content of the waste during the retorting process of oil shale.In the oil shale retorting process,the oil shale after crushing through the distillation furnace pyrolysis will produce shale oil vapor,gas,water vapor and other oil and gas volatile products which contained the crushing process was not screened and transportation and friction process to produce oil shale dust,then form a semi-solid hydrophilic substances waste which contain a content of oil,water,dust.Recover shale oil from the oil shale sludge to reduce the harm to the environment and reduce waste of resources.In this paper,the method of the combination of hot water washing and organic solvent extraction was used to treat the oil shale sludge,then the optimal experimental conditions were obtained and the products were studied.The method of hot water washing was used to treat the oil shale sludge.Oil shale sludge was cleaned by pure water in order to study the effects of liquid-solid ratio,agitate rate,temperature,clean time on residual shale oil of the oil shale sludge.Then the optimized condition of cleaning was determined.After screening and remixing the reagents,OP-10:Na2SiO3=1:3(the mass ratio)was selected.Orthogonal tests were conducted,the results from which indicates that the residual oil contained in the sample reduces from 60.31% to 2.84%after agitating for 30 min at 70 °C with agitation frequency at 330 r/min,ratio of liquid to solid at5:1,chemical reagent concentration at 6.0 g/L.By comparing the range,the order of the influencing factors is reagent concentrations > temperature > liquid-solid ratio > agitate rate.After the process of cleaning,the cleaning solution can be recycled and the remaining oil shale sludge can be made into bricks,then it reduces the secondary pollution of the environment.Organic reagent was used to extract oil shale sludge and carbon tetrachloride,dichloromethane,petroleum ether and ethanol were used to extract sludge,The results showed that the extraction rate was stable when the extraction time was 36 h,and the extraction rates were 75.93%,87.02%,80.65%,90.38%.The oil shale sludge was treated by the combination method,LAS,OP-10 and Na2SiO3 were used to clean the oil sludge and the sludge was extracted by carbon tetrachloride,dichloromethane,petroleum ether and ethanol and the extraction time was 36 h,The results showed that the oil removal rate was higher in the combination of the Na2SiO3 cleaning and dichloromethane extraction,the oil removal rate was 58.97%;the clay mineral composition did not change,but the diffraction intensity increased and the illite-montmorillonite mixed-layer disappeared;The SEM pictures of the oil shale sludge shows that a certain influence occurs onthe microstructure of the oil shale sludge during the process of experiment.The oil shale sludge presents net gully structure,with increasing the dispersion degree and the surface area.