| Oil-drilling cuttings are oil-containing solid wastes produced during shale gas exploitation,which are mainly oil slime and oil sand produced during shale gas exploitation.Oil-drilling cuttings because of its high oil con tent and removal difficult;produces large and less comprehensive utilization;high moisture and difficulty in handling;containing heavy metal ions,benzene,phenolic compounds and other toxic substances,has been clearly classified as hazardous waste,and it is urgent to dispose them harmless.In this paper,the mechanochemical process is used to degrade the oil-drilling cuttings,and to prepare the non-sintered ceramsite with the degraded oil-drilling cuttings,and to realize the harmless disposal and resource utilization of the oil-drilling cuttings.Firstly,based on the analysis of the basic characteristics of oil-drilling cuttings,Circulating Fluidized Bed Combustion(CFBC)fly ash and fly ash,the experiment of degradation of oil-drilling cuttings by mechanochemical is carried out.The effect of the mixture ratio of Ca O,Ca O+ CFBC fly ash and Ca O+fly ash on the degradation of petroleum hydrocarbons in the oil-drilling cuttings was studied.The results show that: Fixed ball milling frequency 600 r/min and ball material ratio 3:1,using Ca O and Ca O+CFBC fly ash as additive,the degradation of oil-drilling cuttings is better than Ca O+fly ash;When the ratio of Ca O is 60%,the oil content can be reduced to 2.05%;When the Ca O+ CFBC fly ash is used as additive and the content of the oil-drilling cuttings is 50%,the oil content of the sample is 1.92% and the oil content of the cuttings is 40%,and the oil content is 0.927%.The results show that the structure of the benzene ring in the oil-drilling cuttings is gradually broken under the mechanochemical.The chlorine atoms begin to fall off,but the functional groups in the oil cuttings samples are not changed obviously,and the long carbon chains in the petroleum hydrocarbons still exist,which indicates that some oil pollutants and organic compounds have been degraded under the mechanochemical.Secondly,on the basis of Prophase Experimental Research,the solidification treatment of oil-drilling cuttings was carried out,and the curing effect of oil-drilling cuttings was characterized by compressive strength and anti leaching performance of solidified body.The results show that the compressive strength of the solidified body decreases with the increase of oil-drilling cuttings,and the compressive strength of CFBC fly ash group is higher than that of cement group.The oil content of solidified body leaching rate increases with the increase of oil-drilling cuttings,and the oil content in the leaching solution of cement solidified body is higher than the CFBC fly ash solidified body.When the amount of oil-drilling cuttings is 50% and 60%,the content of petroleum in the cement-solidified body exceeds the national standard.The degradation mechanism and curing mechanism of oil-drilling cuttings by mechanochemical were analyzed by particle size analysis,XRD,FT-IR and SEM.The results showed that the agglomeration effect of particles was found in the process of mechanochemical treatment of oily cuttings.The high temperature,lattice defects and chemical bond faults produced by mechanochemical can induce the degradation of oil and organic pollutants in oil-drilling cuttings.The entringite and C-S-H gels are produced in the hydration process of the CFBC fly ash solidified body and the cement-based solidified body.However,the structure of the CFBC fly ash solidified body is more compact than that of the cement-based solidified body,and the distribution of the entringite and C-S-H gels in the CFBC fly ash solidified body is more uniform than that in the cement-cured body.Finally,using oil-drilling cuttings as raw materials to prepare the non-sintered ceramsite,the prepared non-sintered ceramsite products were tested for their properties such as stacking density,specific surface area,water absorption rate and barrel compressive strength.The results show that: the performance of CFBC-non-sintered ceramsite are better than OPC-non-sintered ceramsite;the optimum water amount of CFBC-and OPC-non-sintered ceramsite is 95 m L and 70 m L,respectively.The best curing temperature of CFBC-and OPC-non-sintered ceramsite is 60oC,and the curing time is 12 h;the surface roughness of the OPC-non-sintered ceramsite is uneven,there are many ravines and there is no obvious pore structure,but the surface of the CFBCnon-sintered ceramsite has many evenly distributed small voids.A large number of C-S-H gels and AFt clusters are interwoven,and the distribution is more uniform than that of the OPC-non-sintered ceramsite.From the environmental safety point of view,the mechanochemical method was used to degrade and cured oil-drilling cuttings.At the same time,the use of a new free-burning process to prepare non-sintered ceramsite,the non-sintered ceramsite has excellent physicochemical properties,and has a great application prospect in building materials,subgrade materials and fi ltration materials,and realizes the harmless disposal and resource utilization of oil-drilling cuttings. |
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