Hu Hongbo Li Yanli Science and Technology Daily reporter Zhang Jingyang
The reporter recently learned from the Inner Mongolia University of Science and Technology that the team of Professor Li Mei, a national Jieqing and Yangtze River scholar, with the goal of controlling the three wastes of rare earth pollution at the source and improving the utilization rate of resources, has reconstructed a set of high-efficiency enrichment of rare earth minerals - roasting and decomposition of high-grade rare earth concentrates - clean extraction of rare earths and recovery of associated elements fluorine, phosphorus and thorium. This new technology solves the problem of pollution of the three wastes (waste gas, waste water, waste residue) of rare earth smelting.
Rare earth is the characteristic resources of Inner Mongolia, rare earth industry is also a characteristic industry of Inner Mongolia Autonomous Region, nearly 40 years, the local rare earth smelting has been using concentrated sulfuric acid high temperature roasting process, there is a serious problem of three waste pollution for a long time, the precious associated resources in the concentrate fluorine, phosphorus, thorium not only did not recycle, but caused pollution to the environment, rare earth smelting three waste pollution problems have been restricting the sustainable development of the rare earth industry.
In view of the problems faced by rare earth smelting, in 2017, the autonomous region launched the implementation of the "Mixed Rare Earth Concentrate Clean and Efficient Extraction New Technology Industry Demonstration Project" major scientific and technological project, aiming to treat the three wastes at the source and improve the utilization rate of resources. The new technology of smelting developed by the research team can replace the concentrated sulfuric acid roasting process that has been used for nearly 40 years, fundamentally solve the problems of three waste pollution and waste of associated resources extracted by rare earths, realize the green and efficient extraction of rare earth resources, add sodium fluoride, sodium phosphate and other chemical industries, realize the recycling of rare earth associated resources, and truly transform the advantages of rare earth resources in Inner Mongolia into the economic advantages of green development.
Li Mei said: "The beneficiation part of the new technology has changed the pattern that Baiyun Obo Mine can only produce 50% rare earth concentrate, increasing the concentrate grade to 65% and increasing the recovery rate by 15%, solving the bottleneck that the beneficiation cannot achieve high grade and high recovery rate at the same time, and realizing the industrialization promotion of high-grade rare earth concentrate." The new technology not only brings huge economic benefits to enterprises, but also provides technical support for the rapid development of Baotou's rare earth industry. ”
3000 tons/year high-grade rare earth and associated resources clean and efficient extraction of new technology demonstration line (Courtesy of Inner Mongolia University of Science and Technology)
Li Mei introduced that the smelting process of the new technology can obtain a high purity mixed chlorinated rare earth solution with a recovery rate greater than 93%, and the by-products such as fluorine, phosphorus, and thorium that cause pollution in the smelting process can also be recycled and reused, cutting off the source of pollution from the source. The new process can obtain sodium fluoride by-products with purity and recovery rate greater than 95%, and trisodium phosphate by-products with a purity greater than 98% and a recovery rate greater than 95%; more than 95% thorium is recovered in the form of a rich, and only 30 kg of thorium enrichment is produced per ton of rare earth concentrate (of which thorium content is 8% and rare earth content is about 30%). It is worth mentioning that thorium enrichment is a potential nuclear fuel that can be recycled when the policy allows, and the rare earths in it can also be recovered in the process of recycling.
At present, the smelting part of the new technology has built a demonstration line with an annual output of 3,000 tons of mixed rare earths and associated resources for clean and efficient extraction, and is currently in trial production. Through the research and development of a series of innovative technologies, Professor Li Mei's team has made the economic, social and environmental benefits of this new set of new technologies and processes more significant, and finally formed a new technology system for clean and efficient extraction of hybrid rare earth concentrates, further promoting the source innovation of rare earth smelting technology in China.