高温改性铁尾矿对水体中磷的去除性能

为探究铁尾矿对水体中磷去除能力与过程，并进一步提高其去除性能，采用高温方法对铁尾矿进行改性。以温度、恒温时间、升温速率为试验因素，以单位去除量为响应值设计响应面试验，并在此基础上依据动力学、等温线、热力学分析铁尾矿改性前后的除磷过程与性能。结果表明，经高温600℃改性的铁尾矿对水体中磷的单位去除量最大为2.43 mg/g，是未改性前的2.46倍。并结合文献和铁尾矿XRD矿物成分分析推测Fe₃O₄对水体中磷的去除起主要作用。回归模型极显著（P < 0.0001），该模型的决定系数R2大于0.99，说明建立的回归方程可靠。从响应面试验得到的最优条件为改性温度627.84℃，恒温时间得3.00 h，升温速率为9.82℃/min，预测最大单位去除量为17.43 mg/g。铁尾矿改性前后对磷的去除均属于非均匀表面的化学吸附，水中磷的去除过程更接近Freundlich等温模型，根据Langmuir等温模型估算改性前后铁尾矿对水体中磷的最大去除量分别为0.19 mg/g和149.97 mg/g，铁尾矿对磷的去除均较易发生。△H₀>0反应需要吸热，温度升高可提高铁尾矿对水中磷的去除作用。 

Removal Performance of Phosphorus from Water by High Temperature Modi-fied Iron Ore Tailing

In order to improve the phosphorus removal capacity and investigate the process of iron ore tailing in water, the iron ore tailing was modified by heating. With the aim of phosphorus removal capacity, the response surface test was designed by taking temperature, time of constant temperature and heating rate as factors value. Moreover, the phosphorus removal process and performance of iron ore tailing before and after modification were analyzed by kinetics, isotherm and thermodynamics. The results shown that the maximum removal capacity of phosphorus by modified iron ore tailings is 2.43 mg/g at 600 ℃, which was 2.46 times that unmodified. Furthermore, It was concluded that Fe₃O₄ played a major role in increasing phosphorus removal capacity combined with literature and tailing sand composition analysis. The response surface regression model was significant (P < 0.0001) and the determination coefficient R2 was greater than 0.99, indicated that the regression model was reliable. The optimal modification conditions obtained from response surface test were as follows temperature 627.84 ℃, constant temperature 3.00 h, heating rate 9.82 ℃/min, which predicted maximum removal capacity of 17.43 mg/g. The removal of phosphorus by iron ore tailing before and after modification was chemisorbed on non-uniform surface. The removal process of phosphorus from water were closer to Freundlich isothermal model. Moreover, the maximum removal amount of phosphorus in Langmuir isothermal model by iron ore tailing before and after modification were estimated as 0.19 mg/g and 149.97 mg/g, respectively. Meanwhile, the removal of phosphorus by iron ore tailing was easy to occur, △H0>0 shown that removal process was endothermic and the removal capacity of phosphorus by iron ore tailing could be improved by increasing the temperature.