摘要
该文结合湿法酸浸赤泥与均相沉淀法制备磷酸铁,提出了赤泥中的铁(Fe)、铝(Al)、钛(Ti)梯级分离工艺。首先对赤泥进行碱焙烧-水淬,以焙烧温度900℃、焙烧时间90 min、纯碱/赤泥投料比为0.5∶1进行碱焙烧后,水淬焙烧产物Al的水淬浸出率达69.91%。其次进行水淬渣的酸浸,得到富含Fe、Al、Ti的酸浸液,在浸出时间1.5 h、浸出温度120℃、硫酸浓度6.0 mol/L、固液比为1∶6的最佳工艺条件下,Fe、Al、Ti浸出率分别达到90.43%、69.48%、95.63%;再次将酸浸液高温氧化水解回收Ti,Ti的回收率达76.79%,Fe组分损失率仅4.9%。而后用氟化钠分离酸浸液中的Al元素制备冰晶石,在F/Al摩尔比为1∶6、初始pH为1.0、反应温度25℃、搅拌反应1 h的条件下,Al的回收率达98.45%,制得纯度较高的冰晶石(Na3AlF6)。最后用均相沉淀制备磷酸铁,在投料Fe/P摩尔比为1∶1.1、双氧水过量1.2倍、反应pH为1.8、反应温度90℃、反应时间4 h的最佳工艺条件下制备的磷酸铁晶形良好,符合标准质量要求。该工艺流程简单,通过梯级分离实现了铁、铝、钛元素的回收利用,为拜耳法赤泥资源化利用提供了新思路。
This study comprehensively investigates the synthesis of iron phosphate from Bayer red mud utilizing a sequential process encompassing wet acidleaching and homogeneous precipitation,accompanied by a graded extraction strategy foriron(Fe),aluminum(Al),and titanium(Ti).Initially,the red mud undergoes alkali roasting at 900℃for 90 minutes with a soda ash/red mud ratio of 0.5∶1,followed by water quenching,achieving a leaching rate of 69.91%for the water-quenched product.Subse⁃quently,an acid leaching step is performed on the water-quenched slag to enrich an aqueous solution with Fe,Al,and Ti.Under the optimal process conditions of leaching time of 1.5 h,leaching temperature of 120℃,sulfuric acid concentration of 6.0 mol/L,and solid-liquid ratio of 1∶6,leaching efficiencies of 90.43%(Fe),69.48%(Al),and 95.63%(Ti)are achieved.Further,Ti is selectively isolated via oxidation and hydrolysis at high temperatures,yielding a Ti recovery of 76.79% with minimal Fe loss 4.9%.Subsequently,sodium fluoride is employed to separate Al from the acid leachate in order to produce high-purity cryolite(Na3AlF6),achieving an Al recovery rate of 98.45% under the conditions of F/Al molar ratio of 1∶6,initial pH of 1.0,tempera⁃ture of 25℃,and stirring for 1 hour.Finally,iron phosphate is synthesized via homogeneous precipitation under the optimal conditions as Fe/P molar ratio of 1∶1.1,H2O_(2) excess of 1.2 times,pH of 1.8,temperature of 90℃,and reaction time of 4 hours.These conditions yield a product of good crystallinity that meets quality standards.This streamlined process effectively recovers Fe,Al,and Ti through gradient separation,offering a novel approach to the resourceful utilization of Bayer red mud.
作者
万晓霞
伍泽广
梅华贤
沈凡熙
WAN Xiaoxia;WU Zeguang;MEI Huaxian;SHEN Fanxi(School of Resource Environment and Safety Engineering,Hunan University of Science and Technology,Xiangtan 411201,China;Hunan Provincial Key Laboratory of Clean Coal Resources Utilization and Mine Environmental Protection,Hunan University of Science and Technology,Xiangtan 411201,China;School of Chemistry and Chemical Engineering,Hunan University of Science and Technology,Xiangtan 411201,China)
出处
《环境科学与技术》
CAS
CSCD
北大核心
2024年第10期77-83,共7页
Environmental Science & Technology
基金
湖南省教育厅科学研究重点项目(21A0315)
内蒙古自治区科技计划项目(2022YFHH0016)。
关键词
拜耳法赤泥
梯级分离
均相沉淀
酸浸
磷酸铁
Bayerian red mud
stage separation
homogeneous precipitation
acid leaching
iron phosphate
