Microbial Induction Of Carbonate Precipitation To Solidify Tailings

Tailing sand is a kind of waste after mineral processing,which is loose and contains a lot of heavy metals.The tailings piled up for a long time not only occupy a large amount of land resources,but also under the effect of rainwater leaching and surface runoff,the heavy metals in them will diffuse and migrate,polluting the surrounding environment.In serious cases,they will even break the dam,causing unimaginable losses to the surrounding residents.In this paper,aiming at the development and utilization of tailings ponds and environmental pollution problems,the metal tailing sand was solidified by MICP technology induced by microorganisms.The effects of solidification with different concentrations of bacteria and cementing solution on the engineering properties and environmental effects of tailing sand were studied in this paper.The main conclusions of this paper are as follows:(1)Using where curing tail sand is feasible,different concentrations of bacteria and cementing fluid concentration after curing tail ore all have a certain strength,within a certain range,the bacteria concentration was positively correlation with unconfined compressive strength,low density cementing fluid to provide source of urea and calcium deficiency,high concentration of cementing fluid can inhibit bacterial activity,suppression in bacteria concentration OD600 = 1.6,cement liquid concentration is 1.0mol/L when curing effect is best,unconfined compressive strength of 778 kpa.(2)Where the tail ore after curing under dry-wet circulation is unconfined compressive strength decreases with the increase of number of dry-wet circulation strength,to reduce overall showed a trend of fast before they are slow and finally tends to be stable,10 times of the dry-wet cycle of sample still has 437 kpa unconfined compressive strength,the instructions will be where curing tail sand is feasible in the technology is applied to engineering.(3)After solidification of metal tail ore under simulated leaching the Cu2 +,Zn2 +and Mn2 +,Pb2 + ion concentration than the control group had significantly lower curing effect of heavy metals as bacteria increase with the increase of the concentration,the concentration of bacteria is lower each have differences,the effect of different solidification cementing fluid concentration in high concentrations of bacteria(OD600= 1.6),cementing fluid concentration is 1.0 mol/L when the best curing effect of heavy metals.(4)From XRD and SEM results,it can be concluded that MICP products are calcite,spherarite and aragonite.From XRD results,it can be concluded that heavy metals Cu,Zn,Mn and Pb mainly exist in the form of Cu2(OH)2CO3,Zn CO3,Mn O2 and Pb CO3.Combining with XRD and SEM results,the principle of MICP is confirmed from the microscopic perspective.