Research On The Engineering Technology And Environmental Impact Of Bayer Red Mud Filling Subgrade

Bayer red mud is the industrial waste discharged from the aluminum industry when it extracts alumina,a large number of dams up not only a waste of land resources,it may also cause harm to the surrounding environment.At present,the effective utilization rate of red mud is very low,so it is urgent to establish an effective way of reducing and large-scale comprehensive utilization.On the basis of research trends at home and abroad and investigation on red mud stockpiling situation in Shandong province,it is important practical significance to study the application of red mud as subgrade filling material and its environmental effects.Based on the basic physical,hydrological and mechanical properties and environmental indicators of Bayer process red mud,analyze its engineering characteristics and environmental classification.Respectively select lime,cement,phosphor gypsum and composite modified materials to modify the red mud,determined the optimal modification treatment scheme by laboratory experiment,and analysis the strength formation and metal ion curing mechanism.Research results show that,When the dosage of the composite modified material is 8%,the 3-day intensity of modified red mud is greater than 2.5MPa,28-day intensity is greater than 2.5MPa,the softening coefficient is greater than 0.80,the leaching concentration of hexavalent chromium and fluoride was reduced by more than 80%,it can satisfy the technical requirement of subgrade.Relying on the experimental road of Beihai New District in Binzhou,study on engineering application of modified Bayer red mud.According to the actual working conditions of subgrade,adopt the hazardous substances dilution migration model,carried out environmental risk assessment on the experimental road,the results shows that the construction of experimental road will not adversely affect groundwater.According to the material properties and environmental control requirements of modified red mud,puts forward the technical requirements for quality control of subgrade construction.Through fixed-point test of load plate test,PFWD and FWD on the forming subgrade,establish the correlation between the modulus of resilience E0,dynamic deformation modulus Ed and the deflection value l of the red mud subgrade.Respectively install groundwater monitoring wells in test section and contrast section,conduct long-term follow-up sampling and comparative test analysis of the surrounding environment(groundwater),the pH value and changes of the concentration of hazardous substances of water samples are basically consistent in the test section and the comparison section,lower than the pollution limits of type-III groundwater after long-term stabilization,consistent with environmental risk assessment conclusions.Use the modified Bayer red mud as a subgrade filling material,it can not only solve the problem of serious shortage of soil source in highway construction,but also to save red mud storage maintenance costs for metallurgical enterprises,has good economic,social and environmental benefits,it is of great significance to promote the reduction,large-scale and comprehensive utilization of red mud.