基于生命周期评价的钨尾矿再选回收钨精矿的环境影响分析

Environmental Impact Analysis on Recovery of Tungsten Concentrate from Tungsten Tailings by Reconcentration Based on Life Cycle Assessment

钨尾矿堆积不仅占用土地,还对生态环境造成影响。钨尾矿再选回收钨精矿能减少钨尾矿堆存带来的环境污染,其附加值较高。本文利用生命周期评价方法,对比分析全浮选工艺及重选-浮选联合工艺,定性定量地研究钨尾矿再选回收钨精矿的环境影响,并通过eFootprint在线分析软件对两种工艺的生命周期评价进行建模。研究选取的功能单位是1 kg钨精矿,系统边界包含再选回收钨精矿过程的主要工序。结果表明,从环境影响评价指标来看,评价对象对初级能源消耗(PED)、水资源消耗(WU)和全球变暖潜值(GWP)的累计贡献值较大,其中全浮选工艺的环境影响评价结果分别为46.8 MJ、38.3 kg、2.9 kg,重选-浮选联合工艺的环境影响评价结果分别为41.9 MJ、46.0 kg、2.5 kg。与全浮选工艺相比,重选-浮选联合工艺通过离心预富集,使得浮选药剂用量减少、需要处理的浮选废水量减少,再选回收钨精矿过程对环境的影响更小,故应优先选用重选-浮选联合工艺,切实保护环境。

The accumulation of tungsten tailings not only occupies land,but also affects the ecological environment.The recovery of tungsten concentrate from tungsten tailings by reconcentration can reduce the environmental pollution caused by tungsten tailings stockpiling,and its added value is high.In this paper,the life cycle assessment method is used to compare and analyze the full flotation process and the gravity concentration-flotation combined process,the environmental impact of tungsten tailings reconcentration to recover tungsten concentrate is qualitatively and quantitatively studied,and the life cycle assessment of the two processes is modelled through eFootprint online analysis software.The functional unit selected in the study is 1 kg tungsten concentrate,and the system boundary includes the main working procedures in the process of reconcentration and recovery of tungsten concentrate.The results show that from the perspective of environmental impact assessment indicators,the cumulative contribution value of the assessment object to the primary energy demand (PED),water use (WU) and global warming potential (GWP) is large,among them,the environmental impact assessment results of the full flotation process are 46.8 MJ,38.3 kg and 2.9 kg respectively,and the environmental impact assessment results of the gravity concentration-flotation combined process are 41.9 MJ,46.0 kg and 2.5 kg respectively.Compared with the full flotation process,the gravity concentration-flotation combined process reduces the amount of flotation reagents and the amount of flotation waste water to be treated by centrifugal preconcentration,and the process of recovering tungsten concentrate by reconcentration has less impact on the environment,therefore,the gravity concentration-flotation combined process should be preferred to effectively protect the environment.