Preparation Of Ceramic Filter Material From Waste Drilling Mud And Its Adsorption Property For Dye Pollutants

Waste drilling mud is discharged from drilling operations, which consists of bentonite, cuttings, water and some chemical additives. Drilling mud plays an important role in drilling operation, such as lubricate and cool drill pipe, maintain the stability of wellbore, suspend and transfer cuttings, balance formation pressure. But waste drilling mud contains heavy metal, alkali, salt, oil and organics which are all toxic pollutants. For it is difficult to dispose, waste drilling mud, oily water and polluted oil are called three public hazards. Nowadays, solid-liquid separation technology is widely used to handle the waste drilling mud. After separation, solid is buried while liquid is discharged after treatment. But there are still other ways like bury without treatment, land farming, formation injection, solidification, cement transformation and burn. Thus it is necessary to reinforce the innocuous treatment of waste drilling mud, reduce or avoid environmental pollution and maintain plough quantity.In order to control waste, the paper discusses the combination of safe treatment and resource recovery of waste drilling mud and handling azo dyes in water. Tianjin waste drilling mud is the research object in the paper. We firstly treated the waste drilling mud by flocculating, condensing and dehydrating and then designed the environmentally friendly ceramic filter ball on the basis of Ca-Mg-Al-Si system. At the same time, the volume density of porous ceramic filter material, porosity and the balance between porosity and crush strength is carried based on the characterization of the TG-DSC、SEM、XRD、XRF measurements. Finally, we get the optimal technology and formula of preparing the porous ceramic filter spheres. Based on the above results, we study the performances of the porous ceramic filter spheres by adsorbing the methylene blue dye and rhodamine dye in water. In addition, the factors and mechanism of adsorption are also discussed. The main findings are as follows:(1) The waste drilling mud of Tianjin as the raw material in this paper and a simple pretreatment is carried out. Fluid was concentrated with coal ash put into at the same time, then material was compressed, and finally the cake was dried and reserved. According to the composition of raw material, we acquire the porous ceramic filter ball with the favor of proper sintering aids like talc, shale and wollastonite which are cheap and abundant, through the processes of distributing, mixing, screening, roasting, beading, drying, and calcining. Through the preparation and study of ceramic filter of G series, we obtained the most optimized recipe is G9(60%mud,20%shale,8%talc,12%albite). G9sample prepared by calcining at1060℃has the properties of are36.65%porosity,20.62%water absorption,12.67Mpa crush strength,81.28%acid resistance and97.31%alkali resistance. SEM results show that a large number of distributed porosities exsit in most samples of G series and the shape of the porosities is similar. Besides, the particles are wrapped by glass phase, the size is even also similar. The content of the waste drilling mud in these ceramic filters is ranging from40%to100%, which could make up use of lots of waste drilling mud. The shape of the ceramic filters can be kept when the calcination temperature is900～1100℃. Moreover, the prepared ceramic filters also have excellent stability and could be separated easily.(2) In order to regulate and control the property index, such as porosity, water absorption rate, bulk density, the research of the composition of raw materials of porous ceramic filter and sinter temperature about the F series ceramic filter is carried out. The result indicated that the porosity can be adjusted to range from8%to40%, water absorption can be adjusted from3%to23%, and other index can be adjusted too. F1sample (Tianjin drilling mud:Shale:K-feldspar:kaolinite40:30:20:10). It was calcined at1090℃, and its porosity, water absorption, volume density are19.95%,10.89%,2.09g/cm3, respectively. The characterization results indicated that the stable mullite was formed in the calcine process, which is helpful for keeping a relatively proper volume density. F8sample (Tianjin drilling mud: Shale:talc:albite:kaolin=60:20:8:12) is calcined at1090℃, and its porosity, water absorption and volume density are30.03%,17.76%,1.93g/cm3, repectively. Due to the lack of the kaolin, less Al2O3content results in the decrease of the amounts of mullite. So the decomposition rate of CaCO3was little influnced by the mullite, and the porosity increased tremendously. The porosity and water absorption is increased when the calcine temperature is reduced. Besides, the adsorption capability of the porous ceramic filter is improved with the increase of the high porosity.(3) RhB and MB dye in water is removed by using waste drilling mud filter and impact factors and adsorption mechanism are discussed in the paper. The adsorption process of the dyes by using the porous ceramic filter material of G9included is rapid stage, medium-speed stage, and slow stage. After the adsorption equation was achieved at240min, the removal rate of methylene blue and rhodamine is80%and77%, repectively. The experiment results indicated that removal rate of methylene blue and rhodamine is increased with the increase of the pH of the solution, and the low pH of solution restricted adsorption performance.(4) The paper discussed the isothermal adsorption model and thermodynamic constant using the filter to remove RhB and MB. The result shows that the adsorption of RhB and MB matches the Langmuir isothermal adsorption model and the Freuulich isothermal adsorption model. The dye ions around the ceramic filter material increases with the increase of initial concentration, which improves the adsorption of dye. Thermodynamic constant study shows the adsorption process of RhB and MB using waste drilling mud filte is spontaneous endothermic, and the increase of the temperature improves the removal of dye. The activation energy of the adsorption of the RhB and MB is69.92kJ/mol and77.23kJ/mol, respectively, indicating the adsorption process is a chemical adsorption.(5) The paper discussed the adsorption kinetics by using waste drilling fluid filter material to remove RhB and MB. The adsorption kinetics shows quasi-dynamic equations and quasi-two dynamic equations can be used to describe the adsorption process; in the three consecutive stages of adsorption process, and the main reason that limits the rate of adsorption is the diffusion in particle.(6) Waste drilling fluid filter material, which prepared by a simple and feasible method, is a adsorption material of green and environmental protection. However, the Al2O3, SiO2which used as aggregate for the preparation of porous filter materials in tradition is expensive relatively and the complex preparation process has limited its application on a large scale. So using abandon drilling fluid instead of the main raw material of traditional porous ceramics production can reduce the environmental pollution and the cost. The adsorption filter material prepared by abandoned drilling fluid has high adsorption capability and excellent adsorption for RhB and MB dye wastewater. It explores a new approach and technology for expanding resource utilization of the abandoned drilling fluid, and providing theoretical direction for the engineering design of the industrial waste water containing dye wastewater and other wastewater treatment. In addition, it provides the theoretical basis for the development of adsorption materials which are cheap, efficient and have good adaptability. This research changes the abandon drilling fluid from low added value to high added value change, conforms to the industry policy of cleaner production and circulation economy in our country, and can promote the sustainable development of the economy.