石膏对赤泥盐分离子迁移的影响

Effects of gypsum amendment on salinity ion migration in bauxite residue

赤泥是氧化铝生产过程中产生的强碱性固体废弃物,盐分含量高,综合利用难。赤泥堆存的环境安全问题正严重威胁氧化铝工业的可持续发展。通过土柱淋溶模拟实验,研究不同处理(G0:不添加石膏;G2:添加2%的石膏;G4:添加4%的石膏)条件下,石膏对赤泥盐分离子迁移与分布的影响。结果表明:与G0相比,G2和G4的初渗率、稳渗率和平均渗透率分别提高31%~36%、16%~33%和9.3%~35%。G0、G2和G4渗滤液的pH值变化范围分别为8.3~9.4、8.8~10.0和9.0~9.8;EC值变化范围分别为1.0~4.0、5.8~7.2和5.2~7.5mS·cm^-1。石膏有利于渗滤液中Na^+、K^+和CO3^2-的迁移,为赤泥堆场盐分调控及赤泥土壤化处理实践提供科学依据。

Bauxite residue is an alkaline waste byproduct generated by the extraction of alumina from bauxite,with strong alkalinity and high salinity.Disposal of bauxite residue(red mud)became an increasing concern to the sustainable development of the alumina industry.A leaching column experiment was conducted to study the effects of different treatments(G0:no gypsum,G2:2%gypsum,G4:4%gypsum)on migration and distribution of salt in bauxite residue.The results are given as follows.Compared with the control group,gypsum led to increases of the initial permeation rate,the stable permeability rate,and average permeation in water leaching by 31%-36%,16%-33%,and 9.3%-35%,respectively.The pH ranges of G0,G2,and G4 in water leaching are 8.3-9.4,8.8-10.0,and 9.0-9.8,respectively.The EC values of G0,G2,and G4 in water leaching are 1.0-4.0,5.8-7.2,and 5.2-7.5 mS·cm^-1,respectively.Addition of gypsum in bauxite residue is beneficial to the leaching of Na^+,K^+,and CO3^2-.This study provides a scientific basis for the control and prevention of salinity and the soil formation of bauxite residue.