Effect of substrate amendment on alkaline minerals and aggregate stability in bauxite residue

基质改良对赤泥碱性矿物转变和团聚体稳定性的影响（英文）

Bauxite residue is an alkaline waste material in the process of alumina production due to its characteristics of higher salinity and alkalinity,which results in environmental issues and extremely restricts the sustainable development of alumina industries.In this work,we conduct a column experiment to study the effects of two amendments on aggregate stability and variations in alkaline minerals of bauxite residue.The two amendments are phosphogypsum(PG)and phosphogypsum and vermicompost(PVC).The dominant fraction in aggregate is 1–0.25 mm in diameter on the surface,which takes up 39.34%,39.38%,and 44.51%for CK,PG,and PVC,respectively.Additions of PG and PVC decreased pH,EC,ESP,exchangeable Na^+concentration and the percentage of alkaline minerals,and then increased exchangeable Ca^2+concentration in bauxite residue.There was significant positive correlation between pH and exchangeable Na^+concentration,the percentage of cancrinite,tricalcium aluminate and calcite;while negative correlation was found in pH value versus exchangeable Ca^2+concentration.Theses findings confirmed that additions of phosphogypsum and vermicompost have a stimulative effect on aggregate stability in bauxite residue.In particular,amendment neutralization(phosphogypsum+vermicompost)in column represents an advantage for large-scale simulation of vegetation rehabilitate in bauxite residue disposal areas.

赤泥规模化处置关系到氧化铝工业的可持续发展,迄今尚无经济可行的处置方法,而赤泥土壤化则是一种极具发展前景的赤泥生态化处置方法。通过土柱实验,研究改良材料(CK:对照;PG:磷石膏;PVC:磷石膏+蚯蚓菌肥)对赤泥团聚体稳定性及碱性矿物相变化的影响,结果表明:在CK,PG和PVC改良条件下1～0.25 mm团聚体颗粒比例最大,分别为39.34%、39.38%和44.51%;改良材料PG和PVC可显著降低赤泥中pH、EC、ESP、交换态Na含量和碱性矿物含量,增加赤泥交换态Ca^(2+)含量;赤泥pH值与交换态Na^+含量和钙霞石、铝酸三钙、碳酸钙的含量呈正相关关系,而与交换态Ca^(2+)含量呈负相关;磷石膏和蚯蚓菌肥联用可明显降低赤泥碱性矿物含量、增强团聚体结构的稳定性。研究结果为赤泥碱性调控及土壤化过程团聚体稳定性调控提供科学依据。