| Gallium is one of the seven scatter metals.It is applied on high technology fields because of its special property.Gallium resources has no independent mineral deposits and co-existing with aluminum,zinc,germanium and lead resources,which is a by-product,extracted in the process of those metals metallurgy.Therefore it is a definite significance in both theory and reality when researching how to recovery and utilization of potential gallium-bearing resources.In this paper,the gallium-bearing red mud from bayer process in Gui Zhou was taken as an object of study.Under the condition of systematically researching physicochemical in properties,directly acid leaching red mud,pretreatment of activated roasting red mud and acid leaching and pretreatment of soda-lime roasting red mud and soda leaching was used to leaching gallium from red mud.The gallium leaching efficiencies was studied through those methods.(1)Through systematically analyzing physicochemical properties of red mud,alumina-silica ratio is 1.2,while aluminum content is 0.0044%.Main phase in red mud is hematite,andradite,cancrinite,crosstie,xonotlite,goethite and diaspore by XRD.Red mud has high specific surface area and its average particle size is 0.889 um that lead to high leaching efficiencies.There are many reactions under the pretreatment process of roasting red mud,such as the evaporation of water,decomposition of crystal water,gases decomposition,material decomposition and combination reactions.(2)In the same experimental conditions,hydrochloric acid,nitric acid and sulfuric acid were selected as leaching agent aiming at optimum agent of leaching gallium efficiencies to choose the best acid.The leaching gallium efficiencies are 97.73%,90.92% and 78.33%,respectively,through the contrast experiments.Therefore,hydrochloric acid has been chosen to leaching gallium agent.(3)A systematic test,pretreatment of soda-lime roasting red mud and soda leaching,was carried out to leach gallium and aluminum.The effects of roasting temperature,roasting time,soda ratio and calcium ratio on roasting behavior of gallium and aluminum were investigated and the optimum conditions for roasting the two metals were determined.The experimental results showed that the average leaching efficiencies of gallium and aluminum were 68.99% and 58.68% including roasting temperature of 900?,roasting time of 1 h,soda ratio of 1.2,calcium ratio of 2.0,leaching temperature of 70?,leaching time of 0.5h,liquid-to-solid ratio of 4 and carbonic acid content of 100g/L.Gallium content in leaching solution is 3~5mg/L.(4)A systematic test,acid leaching red mud,was carried out to leach gallium and aluminum.The effects of dosage of hydrochloric acid,temperature,time and liquid-solid ratio on leaching behavior of gallium and aluminum were investigated and the optimum conditions for leaching the two metals were determined.The experimental results showed that the average leaching efficiencies of gallium and aluminum were up to 94.77% and 88.44%,respectively.Under the conditions including acid addition coefficient of 1.2,liquid-to-solid ratio of 8,and leaching temperature of 55? and leaching time of 4h at normal atmospheric pressure.Gallium content is 3~4mg/L in leaching solution.(5)A systematic test,pretreatment of activated roasting red mud and acid leaching,was carried out to leach gallium and aluminum.The effects of roasting temperature,and roasting time on roasting behavior of gallium and aluminum were investigated and the optimum conditions for roasting the two metals were determined.The experimental results showed that the average leaching efficiencies of gallium and aluminum were 95.29% and 88.36%.Including roasting temperature of 450?,roasting time of 0.5h,acid addition coefficient of 1.2,liquid-to-solid ratio of 8,and leaching temperature of 55? and leaching time of 4h.Gallium content in leaching solution is 1.5~2mg/L.(6)The leaching efficiencies of gallium is to serve as the evaluation index.Relative characteristics of three typical processes in leaching gallium are investigated.relatively high leaching efficiency is beneficial to enrich gallium from red mud by Ion Exchange and Adsorption Resin in future experiment.Therefore the process of acid leaching red mud is best method to leaching gallium.(7)According to the research data,it shows that the relationship of leaching efficiencies between gallium and aluminum are in obviously positive correlation under the experimental condition and the leaching efficiencies in gallium is higher than aluminum. |
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