Experimental Study On Improving The Tailings Of A Metal Mine By Microbial Grouting

Abstract:Microbial induced calcium carbonate precipitation solidified sand technology,not only the interdisciplinary theory and technical innovation,but also the re-integration of land resources and new means of environmental protection.In this article,the whole process of the expansion of bacillus cereus was described,and the whole steps of the culture process were introduced in detail,and some parameters were set up and their principles were expounded.And then using bacillus bacillus for sand curing test,the main results are as follows:(1)A new test device for microbial grouting solidified sand was designed on the basis of the previous experimental study.The device has the advantages of strong water permeability,improved sample uniformity and improved curing effect.The preliminary experimental results showed that the reaction generator has a certain effect for microbial grouting solidification of sand.(2)The experiments on improving the tailings of a metal mine by microbial grouting were carried out by using the reaction generator.the results of triaxial compression test of the sand column after curing were as follows:Under confining pressure of 100 kpa,the axial stress and the maximum shear stress of the three cured specimens with diameters of50mm,39.1mm and 65mm are much larger than those of untreated original sand samples:The axial stress increased 3.03 times,3.06 times,2.66 times,and the maximum shear stress increased 2.27 times,2.22 times,1.96 times.Experimental results are better.(3)Three-factor three-level experiment of microbial grouting solidification tailings were designed and analyzed by using design-expert software.get the following conclusions:1)Under the interaction of three factors,the order of influence on maximum axial stress was:(bacterial concentration×ratio of nutrient solution)>(bacterial concentration×reaction time)>(ratio of nutrient solution ratio×reaction time).The order of the single factor is:Reaction time>nutrient solution ratio>bacterial concentration.2)When the bacteria OD600 value of 0.9 to 1.5,nutrient solution ratio of 0.5 to 1.5,the reaction time of 7 to 21 days,a good reinforcement effect can be get through a reasonable combination of the three factors,the maximum axial stress is above 530 kPa.3)The predictive model for predicting the maximum axial stress is deduced theoretically as follows:σ_m=246.05+281.41667A+102.55B+14.59286C+101.66667AB-0.95238AC+0.57143BC-149.72222A~2-101.9B~2-0.42296C~2.(σ_m-Maximum axial;A-bacterial concentration;B-ratio of nutrient solution;C-reaction time)4)According to the optimization scheme,the maximum axial stress of 610.275 kPa was obtained when the OD600 value of the bacteria was1.28,the nutrient solution ratio was 1.19,and the reaction time was 16.46days.