Life Cycle Assessment Of Scandium Oxide Extraction From Rare Earth Tailings Of Bayan Obo Mine

Among scandium products,scandium oxide?Sc₂O₃?is one of the most important products.It is widely used in chemical industry,laser,medical treatment,activator,ceramics and other fields and has broad development space.In the process of scandium oxide extraction,resource consumption and waste discharge will cause serious harm to the environment.Life cycle assessment?LCA?is a quantitative analysis of the environmental impact of a product or process over its entire life cycle.In this paper,life cycle assessment?LCA?method was used to evaluate the environmental impact of scandium oxide extraction from rare earth tailings in Bayan Obo.This study is the first study of scandium oxide product life cycle assessment,the research is based on China's Baotou Steel?Group?Co.,LTD.?Bayan Obo ore holding company?of Baotou Steel Group Mining Research Institute?Co.,LTD.?,the relevant public information collection and field investigation,to Bayan Obo ore rare earth tailings extracting scandium oxide of life cycle assessment.This study shows that the total environmental impact potential of scandium oxide extraction from rare earth tailings of Bayan Obo mine is in order Human toxicity non-cancer,Global Warming Air,Human Health Particulate Air,Acidification,Smog Air,Resources,Fossil fuels,Human toxicity cancer,Ecotoxicity,EutroPHication and Ozone Depletion Air.Among them,Human toxicity non-cancer is the most important type of environmental impact,accounting for 33.98%of the total environmental impact value,and the total characteristic value is 4.13E-04 CTUh.Global Warming Air comes next with 15.20%,and the total characteristic value is 3.78E+03 kgCO₂-equiv.The total environmental impact values at each stage are in the order of iron flotation,secondary iron flotation,mixed flotation and niobium flotation and so on,which respectively account for 31.72%,21.87%,10.50%and 9.61%of the total environmental impact values.In the process of scandium oxide smelting,oxalic acid precipitation is a key process affecting the environment.During the precipitation process,the amount of oxalic acid not only affects the precipitation rate and purity,but also is an important factor affecting the environment.Under the reaction conditions of 80?and 1.5 PH,the amount of 10ml oxalic acid is appropriate,which can not only guarantee the precipitation rate and purity of scandium oxalate,but also cause little environmental pollution.The sensitivity of input materials in the whole life cycle of scandium oxide extraction to Human toxicity non-cancer,Global Warming Air and Acidification was analyzed.The results show that in the iron flotation stage,the substances with the highest sensitivity to the three environmental impact types are steam,with the sensitivity of 3.380%,2.630%and 2.310%respectively.The lowest sensitivity to water was 0.002%,0.003%and 0.001%,respectively.At the stage of normal pressure acid leaching,pressure acid leaching and extraction enrichment,the substances with the lowest sensitivity to the three types of environmental impact are electricity,and the substances with the highest sensitivity are sulfuric acid,steam and extraction agent,respectively.