2021.04.28
On the 20th, the reporter learned from Baotou Rare Earth Research Institute that the "sulfuric acid slurry decomposition of mixed rare earth concentrate" process independently developed by the Institute fundamentally solved the problems such as difficult waste gas and wastewater treatment, waste of resources and large consumption of chemical raw and auxiliary materials in the rare earth smelting process, and realized the green and efficient extraction and high-value utilization of rare earth and associated fluorine, phosphorus and other resources.
Cui Jianguo, deputy director of hydrometallurgy Research Institute of Baotou Rare Earth Research Institute, told reporters that "at present, a number of core invention patents of our technology have been authorized, and international patents have been accepted by the United States, Japan and the European Union through PCT. The overall technical indicators are at the international leading level and have been evaluated as subversive technologies by many industry experts."
In recent decades, the smelting of mixed rare earth concentrate has been treated by concentrated sulfuric acid high-temperature roasting decomposition process. "Although rare earth resources can be extracted in a short process, phosphorus, iron and other resources are retained in the waste residue, and sulfate wastewater and acid tail gas with complex components are formed, which increases the difficulty of treatment of 'three wastes'." Cui Jianguo frankly said that key technical problems such as comprehensive recovery of CO associated resources such as fluorine and phosphorus and acid-base recycling have become the bottleneck restricting the sustainable development of the rare earth industry.
The sulfuric acid slurry decomposition process of mixed rare earth concentrate combines the smelting process pattern, existing problems and industrial demand of rare earth minerals in China, adopts the synergistic effect of weakening concentration and increasing ore acid (alkali) ratio, supplemented by cyclic decomposition strengthening technology, and uses sulfuric acid solution and sodium hydroxide solution to decompose fluorine and phosphorus containing minerals respectively, so as to realize the co generation of fluorine, phosphorus Comprehensive recovery of silicon and other resources and acid-base recycling are a new technology for comprehensive utilization of multiple resources.
Bayan Obo mixed rare earth concentrate is one of the globally recognized refractory minerals, which is mainly composed of bastnaesite and monazite. Wang Zhe, a researcher at the Institute of hydrometallurgy of Baotou Rare Earth Research Institute, introduced that they applied this technology to treat Bayan Obo mixed rare earth concentrate and found that the slurry decomposition with sulfuric acid can selectively preferentially decompose bastnaesite, control the fluorine in monazite to be less than 0.5%, and the sulfuric acid consumption per ton of rare earth oxide products to be less than 1.25 tons. The amount of radioactive waste residue is greatly reduced, and the high reflectivity material is prepared by decomposing and recovering phosphorus by-products. At the same time, realize the recycling of acid and alkali.
The process can be applied not only to Bayan Obo rare earth concentrate, but also to Sichuan bastnaesite, American mantingpas mixed rare earth ore and Bayan Obo low-grade fluorite ore.
At present, the slurry decomposition project has built a pilot test line with an annual processing capacity of 1000 tons in North rare earth group company. With the continuous promotion of the expansion research and the gradual solution of the connection problems of various links of the process, the application of this technology will be broader and the social and economic benefits will be more significant.
