Research On The Removal Of Alkalization In Red Mud By Using Flue Gas And Utilization Of By-products

Red mud is an industrial byproduct in the extraction process of alumina from bauxite,which is one of the largest industrial solid wastes having little utilization.Most of the red mud in our country belongs to Bayer red mud.The worst effect of red mud is its high pH value,reaching 12-13,which belongs to harmful waste residue.It leads to soil alkalization,and underground water pollution during the red mud storage processing.During the progress of utilization of red mud,it needs to solve the problem of whiskering of red mud.Adopting the concept of waste treatment,it designs technological process of removing alkali in Bayer red mud by making use of coal-fired flue gas and preparation of multiple flocculant.Based on analyzing the main composition of red mud,the process of using acid gas of Bayer red mud is studied;On the basis of this,a novel multiflocculant was prepared by a series of reactions with dealkalization red mud,fly ash and waste acid.The composite plate was prepared by dealkalization red mud and fly ash,which realizes full utilization of Bayer red mud.Fistly,a low cost dealkalization process for red mud was designed and experiments process is carried out based on 10 tons coal-fired boiler.Through different spraying ways it can be used to remove the adhesion salt?alkaline?in the red mud and prolonging the spraying time,the remaining alkali content of the red mud can be effectively reduced.Researches of the residual alkali content in red mud and pH in the slurry is studied during the dealkalization reaction.Theexperiments indicated that under the scale-up pilot condition,the results show that through spray of red mud slurry and acidic condition it can effectively reduce the alkali content,which can be reduced to 0.4 wt%,with the removing effect at 95.5%.SO₂concentration was effectively reduced and the removal rate was 91.2%.Preparation of multiple flocculant is studied using dealkalization red mud as the raw material,and it is evaluated aluminum and iron leaching rate of dealkalization red mud,turbidity removal effect of multiple flocculant and effects to the turbidity removaling by adding PDMDAAC into multiple flocculant.The ratio of the optimized dealkalization red mud and hydrochloric acid was 1:3,and the concentration of hydrochloric acid was 25%and positive for the leaching of dealkalization red mud.The turbidity effect of multiple flocculant and industrial PAC is similar,and the turbidity of the simulated water can be reduced well,with the dosage of multiple flocculant at 0.9 mL/L with the turbidity removal rate at 98%.The experiment was also carried out to prepare multiple flocculant by using dealkalization red mud and fly ash.The optimizing conditions were obtained that ratio of sodium carbonate:fly ash:dealkalization red mud was 1:1:3.The turbidity removal result of multiple flocculant was relatively high.The turbidity removal rate was 98.8%when dosage of multiple flocculant was 0.9 mL/L.At last,in order to realize the full component of dealkalization red mud,dealkalization red mud and fly ash was used as raw materials,using modifier?KH550?pretreatment and preparation of composite plate is carried out.The quality proportion of dealkalization red mud to fly ash is 2:3.While fillings could reach 40 wt%and,mechanical property of composite plate samples spline is as followed,tensile strength is 23.5 MPa,the bending strength of 28.7 MPa.By adding carbon materials including graphite mineral powder,grapheme and carbon powder,the electromagnetic and thermal conductivity of composite plate can be improved,which electromagnetic is21.45 dB during the frequencyranging from 9-12 GHz and thermal conductivity of composite plateis0.4233 W/?m·K?.