Life cycle assessment on boron production: is boric acid extraction from salt-lake brine environmentally friendly?

摘要

No information is currently available on potential environmental impact of boric acid solvent extraction from salt-lake brine although boron production is important for industry, agriculture, and human well-beings. Life cycle assessment (LCA) was firstly used by this study to evaluate the environmental impact of boron production using extraction method with the functional unit of 1-ton boric acid. CO_2 was the pollutant with the highest emission amount among the target pollutants, while both extraction and reverse extraction stages contributed to 61.6% of total emission amount for the boron extraction technique. Global warming potential (GWP) and acidification potential (AP) of producing 1-ton boric acid by extraction technique reached 5.52×10~3 kg CO_2 eq and 28.0 kg SO_2 eq, respectively. Extraction/dry stage contributed to the highest/ lowest percentage of environmental impact indices by following the order of extraction > reverse extraction > acidifica-tion>dry. Life cycle cost for 1 ton of boric acid was estimated as $1054.83 with 67.5% of internal cost. Approximately 1.59 ton of indirect water and 6010 kWh of electricity were consumed to produce 1 ton of boric acid. The emission amounts of pollutants for nanofiltration boron-production technique were 1.4-1.7 times those for extraction technique. GWP and AP of boron extraction production were comparable with those of the other production processes. The findings of this study will provide the theoretical basis and quantitative data for the sustainable development and cleaner production of boron industry.