Study On Ultrasonic Assisted Modification Of Calcined Coal Series Kaolin And Its Oil Adsorption Performance

As a province with large coal resources,Shanxi Province produces a large amount of solid waste in the process of coal mining and washing every year,and its governance issues have attracted more and more attention.Coal gangue,also known as coal-series kaolin,is one of the solid wastes.It is an associated mineral of coal.Its discharge and accumulation every year cause a series of environmental problems such as land waste and environmental pollution.The utilization of resources and high value-added utilization of it has gradually become the key of modern scholar's research.As the largest application industry of coal-series kaolin,the papermaking coating and filler industry has increasingly higher requirements for calcined coal-based kaolin.The preparation of calcined coal-series kaolin with high oil absorption and whiteness has always been an important research direction.This article starts with the factors such as particle size distribution,specific surface area and pore structure that directly affect the oil absorption of calcined coal-series kaolin.Ultrasonic-assisted methods were used to carry out ultrasonic crushing experiments on coal-series kaolin,ultrasonic-assisted intercalation-peeling exploration coal-series kaolin experiments,and ultrasonic crushing and kaolin calcination process combined exploration experiments,and the oil absorption value of the samples was evaluated.Use scanning electron microscopy(SEM),X-ray diffraction(XRD),infrared spectroscopy(FTIR)and other testing methods to characterize the surface properties and microstructure of the samples before and after treatment,and use the BET specific surface area test analyzer and laser particle size tester to analyze the pore structure and particle size distribution of the samples before and after treatment.Through the above research,the main conclusions drawn are as follows:(1)Ultrasonic waves have obvious crushing effect on kaolin,and the crushing mechanism of kaolin with different textures is different.After ultrasonic treatment,Suzhou soft kaolin showed a reduction in the area of lateral lamellae,and the particle size distribution shifted to the direction of small particles;Maoming sandy kaolin showed the thinning of longitudinally stacked lamellae,with little change in particle size distribution;The Shuozhou hard coal-series kaolin exhibits an ideal volume crushing effect,with both a reduction in the area of the lateral lamellae and the disintegration of the longitudinally stacked lamellae.(2)Ultrasonic treatment can not only effectively reduce the average grain size of the kaolin sample,but also retain its crystallinity to the greatest extent.In addition,the bond energy of the Si-O bond between the kaolin layers is also improved to a certain extent.(3)Kaolin intercalation DMSO can increase the interlayer spacing to 1.13 nm.Orthogonal experiments of intercalation DMSO under magnetic stirring found that the significant order of its influencing factors is intercalation temperature>DMSO dosage>intercalation time.The best combination is:the dosage of DMSO is 70 m L,the intercalation time is 6 h,and the intercalation temperature is 80?.Under these conditions,the intercalation rate reaches 79.89%.Ultrasonic-assisted intercalation can effectively increase the intercalation rate of coal-measure kaolin.(4)Through the coal-series kaolin intercalation-stripping-calcination orthogonal experiment,it is found that the significant level of the factors affecting the oil absorption value of the final calcined coal-series kaolin is calcination temperature>stripping liquid concentration>intercalation liquid concentration,and the maximum oil absorption value is70.592 g/100g;The coal series kaolin intercalation-calcining orthogonal experiment found that the significant level of the factors affecting the oil absorption value of the calcined coal series kaolin is the concentration ratio of the intercalation liquid DMSO>calcining temperature>intercalation time,and the best oil absorption value is 73.284 g/100g.The calcination temperature has a significant effect on the oil absorption value of kaolin.(5)Ultrasonic treatment and calcining combined treatment experiments found that the sintering problem is more likely to occur after the ultrasonic crushing treatment and then the calcination.The particle size increases after calcination,and the oil absorption value is not as good as that of the original soil calcination.The first calcination followed by ultrasonic refinement and classification treatment can differentiate the particle size of calcined products into different particle size ranges,effectively increasing the oil absorption value of calcined coal-series kaolin,and the best oil absorption value reaches 85.560 g/100g.(6)The introduction of microwave into the calcining process of coal-series kaolin can effectively promote the rapid dehydroxylation of coal-series kaolin and the rapid reaction of organic matter,and realize in-situ pore expansion and expansion of calcined kaolin,thereby increasing the specific surface area of calcined coal-series kaolin.The BET specific surface area of the sample obtained in the experiment was as high as 35.29 m~2/g,the total adsorption pore volume reached 0.2245 cm~2/g,and the maximum average adsorption pore size reached33.35 nm.In this process,all data of calcined Shuozhou coal-series kaolin sample are better than target sample(American kaolin)can be obtained.