Study On Application Of Red Mud, Alumina Production Waste, For Waste Water Treatment

With the development of the industry, the problem of water environment isbecoming more and more serious. Red mud, a waste tailing produced during aluminaproduction, causes serious environmental problem due to its high alkalinity and largeamount. This thesis focus on ruducing the pollution and reusing the red mudreasonably and effectively.The red mud used in this reaseach were obtained from2technology routes (A forByer method and B for mixed technology), Henan Great Wall AluminiumCorporation, China, Their compositons and properties were characterized bymeans of SEM, XRF, XRD and BET techniques. The alkalinity of red mud wastreated with seawater, condensed seawater and brine, respectively. Adsorption ofphosphate, arsenic, arsnate and lead from aqueous solution under different conditonssuch as pH value, time and temperature were also investigated The dynamic andthermodynamic behaviors of the adsorption were analyzed. The results can helpdevelop a new technology to reuse red mud.The2types of red mud are both composed primarily of particles of iron,aluminium, calcium, silica, titanium oxides and hydroxides, hence, the type A has amulti-flake structure, and type B has the clustered structure. The BET analysisindicated that both red mud A and red mud B have the small specific surface. Theharmless treatment of red mud indicated that the results were influenced by theconcentration of salt solution and contact time.Adsorption rate of phosphate by the red mud A was approached to100%in theacidic condition. The adsorption data were well interpreted by the pseudo-secondorder dynamical model and the Langmuir adsorption isotherms. The thermodynamicdata indicated the spontaneous, endothermic and physics chemical adsorption natureof the process. Adsorption of phosphate by the red mud B was effective in wide pHvalue ranges. The adsorption data were well interpreted by the Elovich dynamicalmodel and the Langmuir adsorption isotherms. The thermodynamic data indicated thespontaneous, decalescence and chemical adsorption nature of the process.The optimal pH value for the As adsorption by the2types of red mud wereaffected by the dissociation constant of As. The dynamical experimental data of redmud A is properly correlated with the pseudo-second order dynamical model, meanwhile, that for red mud B is properly correlated with the pseudo-first orderdynamical model and Elovich dynamical model. The experimental data indicated thatAs has powerful affinity with both red mud A and red mud B. So the comparativelylarge adsorption potential caused the adsorption process to proceed easily.The data showed that red mud with high alkalinity was a very efficientunconventional adsorbent for removing Pb2+from waste water at wide pH values. Itwas found that low temperature was benefit for Pb2+adsorption process. This studyindicates that the Pb2+adsorption by red mud was mainly complex reaction, whichgenerated surface complexes precipitation.The study was aimed at devoloping a noval method to treat the red mud and anew red mud adsorbent to treat industrial waste water. The results can not only supplya potential raw materials for construction, but also have great economic benefit owingto its very low cost as a waste.