Solidification Of Heavy Metal Chromium And Recovery Of Iron And Aluminum From Bulk Solid Waste Red Mud

Tens of millions of tons of red mud are discharged every year in China,but the utilization rate of red mud has been maintained at a low level.Most of the red mud piles in red mud reservoirs,and its heavy metal content and high alkalinity are easy to pose a threat to the surrounding environment.Chromium slag is recognized as one of the most dangerous solid wastes,which has highly toxic and carcinogenic.Most of the chromium slag is stored after harmless treatment,but it is easy to turn yellow after detoxification.In order to solve the problem of chromic slag re-yellow and red mud accumulation,red mud and chromic slag were used to replace clay and cooperate with silica to prepare glass-ceramics,so as to achieve the purpose of using waste to treat waste and high price of final products.(1)When the mass ratio of red mud and chromium residue is 9:1,the amount of silica is 50% of the total mass of red mud and chromium residue.After mixing,it is moved into an alumina crucible and heated in Muffle furnace at 10 ? per minute to1200 ? for 2h,then cooled to 600 ? at 10 ? per minute and cooled to room temperature in the furnace.The total chromium leaching concentration of the finished product can reach less than 0.004 mg/L.(2)In order to study the effect of each component in red mud on the curing system,metal oxides were used to simulate the composition of red mud to conduct glass-ceramics.The experimental results show that the alkali sodium in red mud can significantly reduce the melting point of silica,forming liquid glass-coated chromium and crystal phase;Iron and titanium are used as nucleating agents to promote crystal precipitation,while silicon,calcium and aluminum are used as raw materials of glass-ceramics to generate new phase forms and form crystal grids to fix chromium.Using red mud as raw material to prepare glass-ceramics can greatly reduce the comprehensive energy consumption and production cost of glass-ceramics preparation,and can effectively fix chromium in the finished product.This study provides a new way to solve the environmental problems caused by RM and COPR.In order to achieve the maximum utilization of red mud,the author tried to recover aluminum from red mud by alkali fusion,and at the same time exposed the iron oxide,through reducing gas to reduce iron oxide,at low temperature,one step recovery of iron and aluminum.The experimental results show that aluminum can be recovered effectively by alkali fusion at 400?600 ?.Although iron oxide can be reduced to magnetite,artificial magnetic separation cannot effectively separate magnetite and cancrinite.