(397j) Recycling Fe-P Slag As Energy Materials Via a Green Technics
AIChE Annual Meeting
2019
2019 AIChE Annual Meeting
Topical Conference: Innovations of Green Process Engineering for Sustainable Energy and Environment
Conversion of Solid Wastes to Energy and/or Product
Tuesday, November 12, 2019 - 5:45pm to 6:00pm
Recycling waste is significant for the sustainable development of resource and environment. As one of the typical waste slags from phosphorus industries, Fe-P generally has high melting point, plentiful iron and phosphorus elements and other impurities according to their raw materials and reaction technics. In order to recycle Fe-P slag as energy materials like LiFePO4 and FePO4, we have developed various routes including solid-state reaction and hydrothermal methods. The thermodynamics of different reaction processes are analyzed to obtain the possible routes with low energy consumption. Green technics with only water byproduct have been designed using the combined raw materials. LiFePO4 and FePO4 can be successfully obtained using Fe1.5P slag with â“1400°C melting point at no higher than 200°C. The purity and electrochemical performance of the as-synthesized samples are evaluated with various techniques. The conversion processes and key impact factors are discussed in detail. FePO4 with good crystal structure and high purity can be obtained by adjusting the pH values of the product solution from the reaction of Fe1.5P, H3PO4 and H2O2, which can meet the requirements for the production of LiFePO4. On the other hand, LiFePO4 can also be synthesized directly by using the raw materials of Fe1.5P, H3PO4, H2O2 and LiOH. After being further coated with organic carbons using waste sugarcane slag, the as-obtained LiFePO4 exhibits comparative electrochemical performance with that of current commercial samples. The discharge capacity can reach 150 mAh/g, and the capacity fade ratio is less than 1% after 100 cycles at 1.0C. The technics and equipment have also been proposed for mass production of LiFePO4 and FePO4 using Fe-P slag at low temperature. The green technics is interesting to recycle the waste with high melting point as function materials through low-energy consumption way, which is beneficial for the social sustainability with low environmental impact.