Life cycle assessment of feed grade mono-dicalcium phosphate production in China, a case study

摘要

Due to the gradual scarcity of global phosphorus resources and water pollution problem caused by animal excreted phosphorus, feed grade mono-dicalcium phosphate is expected to gradually replace other feed phosphates with its high phosphorus absorption rate, low phosphorus pollution and good economic benefits advantages. This work employs a cradle-to-gate life cycle assessment and life cycle costing methodology to evaluate the environmental impacts and economic costs of feed grade monodicalcium phosphate production. Additionally, a detailed analysis of mono-dicalcium phosphate production using process analysis in the quantification of material and energy usage was done. The normalization of midpoint results showed that the predominate environmental impact was identified as human toxicity, followed by fossil depletion, marine ecotoxicity and particular oxidant formation. The contributions analysis results highlighted that beneficiation, sulfuric acid synthesis and phosphoric acid synthesis are the processes with serious environmental pollution. In addition, key substances which can bring serious environmental burdens were identified as sulfur and electricity, beneficiation reagent and tailings as well as phosphogypsum in this study. The results of sensitivity analysis confirmed that decreasing electricity and sulfur consumption should be priority to realize clean production. The results indicated that 1-ton target product would lead to 11460.96 MJ and 306.92 US $ in energy consumption, life cycle cost. Importantly, when the available phosphate ore grade decreases from 25% to 15% because of gradual phosphate resources depletion, cost related to mono-dicalcium phosphate production was computed as from 300.76 to 332.35 US $. It will provide useful guidance for phosphate enterprises in China under different market price. Based on these results, this work makes interpretations and gives possible recommendations such as optimizing national power structure, improving the sulfur raw material consumption efficiency and increasing the recycled rate of waste heat for operational improvements in mono-dicalcium phosphate production.(c) 2020 Elsevier Ltd. All rights reserved.