Experiment And Research On One-time Mixing-mixing Of Microorganisms To Reinforce Red Mud

With the continuous advancement of China’s industrial modernization,the production of Bayer red mud in the alumina production industry continues to rise,and the demand for large-scale consumption of Bayer red mud is becoming more and more urgent.Summarizing the current measures to reuse Bayer red mud,the comprehensive utilization rate only accounts for about 10%.Nowadays,a large number of Bayer red mud can not be effectively used,the vast majority of piles in the red mud dumping site,not only a large amount of land,but also cause serious pollution to the surrounding environment,due to the problem of production technology,Bayer red mud has extremely high alkalinity and easy to disintegrate and collapse in water and other engineering characteristics.In this paper,the use of green biological building materials microbial cement to strengthen Bayer red mud is used to overcome the problems of unevenness of grouting and easy delamination fracture in the traditional grouting process,and the one-time mixing method is adopted,which greatly improves the compressive strength of Bayer red mud,reduces the strong alkalinity of red mud,eliminates the nature of red mud in water collapse,and improves new methods for the large-scale absorption of Bayer red mud.In this paper,Bacillus pasteurii was selected as the urease strain,Bacillus gliobi as carbonic anhydrase-producing strain,urea as the endogenous carbon source of the sample,and carbon dioxide as the exogenous carbon source,and the reinforcement effect and alkalinity reduction effect of these two strains on Bayer red mud were studied respectively.Furthermore,this paper innovatively combines the application of urease bacteria and carbonic anhydridase bacteria to explore the compressive strength,stress-strain relationship and pH value change law of Bayer red mud under the combined action of strains.The main findings are as follows:(1)The reinforcement of urease bacteria combined with calcium hydroxide on Bayer red mud.Under the synergistic effect of the mixing of Urease bacteria(Bacillus pasteurii)and calcium hydroxide,the engineering properties of Bayer red mud have been greatly improved,and the alkalinity has been greatly reduced.By adjusting the mixing parameters(centrifugal bacteria sludge content,calcium hydroxide content,water-solid ratio,cementation liquid concentration),the specimen cured to the age under the optimal parameters can reach up to 4.4MPa,the compactness of the sample is greatly improved,and the pH value is reduced to 8.2～8.7.From the microstructure observation,it is found that calcium aluminate hydrate and calcium carbonate crystals cement each other to wrap red mud particles,improve pore structure and wrap alkaline substances.(2)The reinforcement of Bayer red mud by carbonic anhydrase-producing bacteria.The carbonic anhydrase bacteria(Bacillus gliobi)were used to promote carbon dioxide hydration,and the effect on the carbonation reaction of the original Bayer method was small.Subsequently,calcium hydroxide was used to calcify the Bayer red mud,and under the control of calcium hydroxide content,water-solid ratio and microbial bacteria powder dosage variables,the strength of the 2d,carbonization pressure of 200 k Pa and carbonization of three hours reached 2.89 Mpa,and the mass growth rate reached 3.78%.(3)The effect of sand doping amount on the carbonization of calcified red mud.On the basis of the above,the pore path of the red mud sample is changed by controlling the standard sand content,the infiltration path of carbon dioxide is increased,and the carbonization effect of the sample as a whole is improved.Under the control of sand dosage,calcium hydroxide content and water-solid ratio variables,the maximum strength of the three-hour carbonization sample reached3.65 MPa and the utilization rate of calcium hydroxide reached 61% after curing 2d,carbonization pressure was 200 k Pa,carbonization three-hour specimen.While reducing the amount of calcium hydroxide,it improves the strength and reflects the application advantages of Bacillus glia.Through microscopic experiments,it was found that a large number of calcium carbonate crystals were generated under the action of microorganisms,and the crystal edges were relatively rounded under the influence of microorganisms.(4)Study on the mixing and reinforcement of Bayer red mud by strains.The urea solution and urease bacteria sludge were configured into a suspension liquid as the mixing water of the carbide adobe blank,and the endogenous carbon source and the external carbon source were combined.It was found that the intensity of the samples increased significantly under the action of combined strains,but the mass growth rate decreased slightly.The external pH of the specimen increases and the internal pH decreases.After further carbonization,it was cured to 7 days,the intensity was further increased,and the external pH value of the sample had the above trend,and the internal pH value was not significantly reduced.