Since the 1950s, Chinese rare earth science and technology workers have conducted extensive research and development on the solvent extraction method for separating rare earth elements, and have achieved many scientific research results, which have been widely used in rare earth industrial production. In 1970, N263 was successfully used in industry to extract and separate yttrium oxide with a purity of 99.99%, replacing the ion exchange method for separating yttrium oxide. The cost was less than one tenth of that of the ion exchange method; In 1970, P204 extraction was used instead of the classical recrystallization method to produce light rare earth oxides; Extracting lanthanum oxide using methyl dimethyl heptyl ester (P350) instead of the classical fractional crystallization method; In the 1970s, the process of ammonia P507 extraction and separation of rare earth elements and the extraction of yttrium with naphthenic acid was first used in China’s rare earth hydrometallurgy industry; The rapid development of extraction technology in China’s rare earth industry is inseparable from the hard work of Yuan Chengye and other comrades from the Chinese Academy of Sciences Shanghai Institute of Organic Chemistry. Various extractants (such as P204, P350, P507, etc.) they have successfully researched have been widely used in industry; The cascade extraction theory proposed and promoted by Professor Xu Guangxian of Peking University in the 1970s has played a guiding role in China’s extraction and separation technology. Simultaneously, a separation process optimized using the cascade extraction theory was proposed and widely applied in the rare earth extraction and separation industry.
Over the past 40 years, China has achieved many remarkable achievements in the field of rare earth separation and purification.
In the 1960s, Beijing Nonferrous Metals Research Institute successfully studied the zinc powder reduction alkalinity method to produce high-purity europium oxide, which was the first time in China to produce products greater than 99.99%. This method is still used in various rare earths throughout the country used by the factory; Shanghai Yuelong Chemical Plant, Fudan University, and Beijing General Institute of Nonferrous Metals collaborated to first use an extraction ion exchange process to enrich N263 with P204 and extract and purify to obtain 99.95% purity yttrium oxide. In 1970,P204 was used to enrich N263 and obtain yttrium oxide with a purity of over 99.99% through secondary extraction and purification.
From 1967 to 1968, the experimental plant of Jiangxi 801 Factory and Beijing Nonferrous Metals Research Institute collaborated to successfully study the process of using P204 extraction grouping – N263 extraction to extract yttrium oxide. In December 1968, a 3-ton/year yyttrium oxideproduction workshop was built, with a purity of 99% of yttrium oxide.
In 1972, a research team was formed by four companies, including Beijing Nonferrous Metals Research Institute, Jiangxi 806 Factory, Jiangxi Nonferrous Metallurgy Research Institute, and Changsha Nonferrous Metallurgy Design Institute. After two years of joint research experiments at Beijing Nonferrous Metals Research Institute, the process of extracting yttrium oxide using naphthenic acid as an extractant and mixed alcohol as a diluent was successfully studied.
In 1974, Changchun Institute of Applied Chemistry discovered for the first time that when separating rare earth elements using naphthenic acid extraction, yttrium was located in front of lanthanum, making it the least easily extractable element in rare earth elements. Therefore, a technology for separating yttrium oxide using naphthenic acid extraction from nitric acid system was proposed. At the same time, the Beijing Nonferrous Metals Research Institute conducted research on the separation of yttrium oxide from hydrochloric acid systems using naphthenic acid, and expanded experiments were conducted in Nanchang 603 Plant and Jiujiang 806 Plant in 1975, using Longnan mixed rare earth oxide as raw material. In 1974, Shanghai Yuelong Chemical Plant, Fudan University, and Beijing Nonferrous Metals Research Institute collaborated to study the separation of yttrium oxide from monazite The mixed rare earth of brown yttrium columbium ore uses the heavy rare earth extracted and grouped by P204 as the raw material, and yttrium oxide is separated by naphthenic acid extraction. A friendship competition was held on three fronts, where everyone exchanged intelligence, learned from each other’s strengths and weaknesses, and finally successfully studied the naphthenic acid extraction and separation process of 99.99% yttrium oxide with Chinese characteristics.
From 1974 to 1975, Nanchang 603 Factory collaborated with Changchun Institute of Applied Chemistry, Beijing General Institute of Non ferrous Metals, Jiangxi Institute of Non ferrous Metallurgy, and other units to successfully study the third generation yttrium oxide extraction process – naphthenic acid one-step extraction and extraction of high-purity yttrium oxide. The process was put into operation in 1976.
At the first National Rare Earth Extraction Conference held in Baotou in 1976, Mr. Xu Guangxian proposed the theory of cascade extraction. In 1977, the “National Symposium on Rare Earth Extraction Cascade Theory and Practice” was held at Shanghai Yuelong Chemical Plant, providing a systematic and comprehensive introduction to this theory. Subsequently, the cascade extraction theory was widely applied in the research and production of rare earth extraction separation and purification.
In 1976, the Beijing Nonferrous Metals Research Institute used Baotou ore mixed with rare earth to extract cerium from the enriched material. The N263 extraction method was used to separate lanthanum praseodymium neodymium. Three products were separated in one extraction, and the purity of lanthanum oxide, praseodymium oxide, and neodymium oxide was around 90%.
From 1979 to 1983, Baotou Rare Earth Research Institute and Beijing Nonferrous Metals Research Institute developed a P507 hydrochloric acid system rare earth extraction separation process using Baotou rare earth ore as raw material to obtain six single rare earth products (purity 99% to 99.95%) of lanthanum, cerium, praseodymium, neodymium, samarium, and gadolinium, as well as europium and terbium enriched products. The process was short, continuous, and the product purity was high.
In the early 1980s, Beijing Nonferrous Metals Research Institute collaborated with Jiujiang Nonferrous Metals Smelter, Changchun Institute of Applied Chemistry, and Jiangxi 603 Factory to carry out the national “Sixth Five Year Plan” research and successfully developed a process technology for fully separating single rare earth elements from Longnan mixed rare earth using the P507 hydrochloric acid system.
In 1983, the Jiujiang Nonferrous Metals Smelter adopted the process technology of Beijing Nonferrous Metals Research Institute’s “naphthenic acid hydrochloric acid system to produce fluorescent grade yttrium oxide from Longnan mixed rare earth” to produce fluorescent grade yttrium oxide, reducing the cost of yttrium oxide and meeting the demand for yttrium oxide for color television in China.
In 1984, Beijing General Institute of Non ferrous Metals successfully studied the separation of high-purity terbium oxide using P507 extraction resin using terbium enriched substances as raw materials in China.
In 1985, Beijing Nonferrous Metals Research Institute transferred the naphthenic acid extraction separation fluorescent grade yttrium oxide process technology to the former German Democratic Republic for 1.71 million Swiss francs, which was the first rare earth separation process technology exported by China.
From 1984 to 1986, Peking University completed industrial experiments on the extraction and separation of La/CePr/Nd and La/Ce/Pr in the P507-HCl system at the Third Rare Earth Plant of Baosteel. More than 98% praseodymium oxide, 99.5% lanthanum oxide, more than 85% cerium oxide, and 99% neodymium oxide were obtained. In 1986, Shanghai Yuelong Chemical Plant applied the optimization design theory of the three outlet extraction process, a theoretical achievement of Peking University’s cascade extraction theory, to conduct a three outlet industrial experiment in the newly built P507-HCl system light rare earth separation process. The industrial experiment scale directly expanded the cascade extraction theory design to 100 tons, greatly shortening the cycle of applying the new process to production.
From 1986 to 1989, Baotou Rare Earth Research Institute, Jiangxi 603 Factory, and Beijing Nonferrous Metals Research Institute developed a P507-HCl system multi outlet extraction process, which allows for the simultaneous production of 3-5 rare earth products through one fractional extraction. The process is short, cost-effective, and flexible.
From 1990 to 1995, Beijing Nonferrous Metals Research Institute and Baotou Rare Earth Research Institute collaborated to undertake the national “Eighth Five Year Plan” scientific and technological research project “Research on High Purity Single Rare Earth Extraction Technology”. Sixteen single rare earth oxide products with a purity greater than 99.999% to 99.9999% were prepared using extraction method, extraction chromatography method, redox method, and cation exchange fiber chromatography method, respectively. This process has reached the international advanced level and won the National “Eighth Five Year Plan” Major Achievement Award.
In 2000, Beijing Nonferrous Metals Research Institute successfully developed the electrolytic reduction alkalinity method to prepare high-purity europium oxide. Due to avoiding the pollution of zinc powder on the product, this process can extract europium oxide with a purity of 5N-6N in one go. In 2001, an annual production line of 18 tons of high-purity europium oxide was built at Gansu Rare Earth Company and put into operation that year.
In summary, China’s rare earth separation and purification technology can be said to be leading in the world, such as naphthenic acid extraction separation of yttrium oxide larger than 5N, P507 extraction method for preparing lanthanum oxide larger than 5N, electrolytic reduction extraction method or alkalinity method for preparing europium oxide larger than 5N, etc. However, the level of automation control in the separation and purification industry is relatively low, and some enterprises have poor quality stability and consistency of high-purity rare earth products. Therefore, it is necessary to further improve the equipment level of enterprises.
Post time: Nov-02-2023