Study On The Effect Of Oil Based Mud Drilling Cuttings Of Shale Gas On The Prepartion And Properties Of Cement Clinker

The optimization and adjustment of China's energy structure has promoted the production of renewable and clean energy,and promoted the continuous increase in the number of shale gas wells.During the production process,oil-based drilling fluids have many advantages such as strong shale swelling inhibition,high temperature resistance,good antifouling properties,good lubricity and so on,so they are widely used in shale gas well drilling engineering.Oil-based drilling fluid mixed drilling cuttings will produce a kind of hazardous waste--oil based mud drilling cuttings?OBMDC?,which is difficult to handle containing long-chain alkanes,surfactants and heavy metal ions.It has great harm to the environment,which greatly hinders the extraction of shale gas.Therefore,how to properly handle OBMDC is an urgent problem to be solved.This paper discusses the feasibility of using cement kiln to co-dispose OBMDC by studying the impact of OBMDC on the production of cement clinker and its performance,and realizes zero pollution and resource treatment of OBMDC.In this paper,the physical and chemical properties of OBMDC are studied firstly.Through the mixture design and raw meal burnability test,the influence of different amount of OBMDC on the calcination and mineral composition of cement clinker is studied by using the addition method?0-5%?and the internal addition method?0-9%?,the optimum amount of OBMDC and the calcination system for preparing cement clinker are determined,and the optimum amount of OBMDC is analyzed physical and mechanical properties of Portland cement.The microfacies of cement clinker's petrography,hydration products,cement hardening structure and pore structure were analyzed through optical microscope,X-ray diffraction,scanning electron microscope and mercury intrusion,and the heavy metal ions in cement hardened slurry were discussed toxicity of leaching.The main conclusions are as follows:?1?The optimal content of OBMDC for the preparation of Portland cement clinker is 3%.At this time,the clinker mineral composition C₃S is about 60%.The best calcination system is950?for 30 min and 1450?for 40 min.Whether it is internal mixing method or external mixing method under this condition,the f-CaO content of the whole clinker is less than 1%.OBMDC can promote the burnability of raw meal and the formation of clinker minerals.?2?Under the best mineral composition and the best calcination system,the 28 d compressive strength of cement mortar prepared by internal mixing method and external mixing method is 56.9 MPa and 61.2 MPa,and the 28 d flexural strength is 10.4 MPa and8.1 MPa,respectively.The strength meets the standard requirements of P·I 42.5 Portland cement.?3?According to the analysis of clinker's optical micrograph,X-ray diffraction pattern and the microstructure and porosity of the hardened cement paste,it was found that the incorporation of OBMDC can play a role in stabilizing the crystal lattice during the cement firing process.When the content of oil-based mud cuttings is 3%or less,the distribution of C₃S and C₂S crystals is relatively uniform,and the porosity of the 28 d cement hardened paste is only about 22%;when the dosage of OBMDC is 4%and 5%,the C₃S and C₂S crystals are larger,and The porosity of the 28 d hardened paste corresponding to the prepared cement is about 25%.?4?When the OBMDC content is 3%,the heavy metal ions of the cement clinker prepared is as follows:The leaching concentration of Pb²⁺is significantly lower than the detection limit,the curing rate of Cr³⁺is 92.8%,and the curing rate of Cu²⁺88.8%,the curing rate of Mn²⁺is99.1%,and the curing rate of Zn²⁺is 99.2%.The leaching of each heavy metal ion meets the requirements of relevant standards.