China's rare earth resources are uniquely endowed. Whether it is total reserves, deposits and mineral types, or regional distribution, light and heavy rare earths, it can be said to be complete and natural. It is undoubted that the development and utilization of China's rare earth resources will have a huge impact on the development of the national economy and science and technology. It was only in the 18th century that human beings began to understand rare earth elements. At that time, people thought that rare earth minerals were scarce, and the extracted oxides looked like alkaline earth (calcium oxide), so they got the names of "thin" and "soil". Modern studies have shown that rare earth elements are not rare, and among the 17 rare earth elements, the abundance in the earth's crust is higher than that of lead . Initially identified 25 minerals containing rare earths. A variety of, not to mention the rare earth reserves on the lunar surface is 3-10 times the potential huge resource in the earth's crust. From the application point of view, due to the unique chemical structure of rare earth elements and compounds, it brings a series of special electrical, magnetic, optical, chemical activity and catalytic functions, so it plays an important role in high-tech fields and agriculture and biology. The production and application of rare earths are still less than a hundred years old. With the development of extraction and extraction technology and the development of rare earth chemistry, materials science and other related disciplines, rare earths will have many more meaningful developments that are unpredictable today. application. It attaches great importance to the development and utilization of rare earth resources in China and the development of scientific research on rare earths. This not only has scientific basis, but also has far-sightedness. With abundant rare earth resources, it is necessary to master a high level of science and technology in order to fully play its role. At present, the urgent task of China's rare earth production is to improve the "rough" (primary) application of rare earths to the "fine, sharp" application stage. We are writing this book to try to systematically summarize the domestic and international rare earth ore beneficiation and extraction research. Results and production practices, including the author's many years of research. It is worth mentioning that, in view of the work done on China's unique rare earth resources - weathered crust leaching rare earth mines, we want to try to theorize and systematically test and test the experiments and results of the extraction process of such minerals by peers and authors. In order to further develop and improve the application of rare earths. The main work of this part is the result of Chi Yu'an's long-term research and application, including doctoral research and postdoctoral research. Authors take this opportunity to the National Natural Science Fund Committee supported the research work, experts from the Ministry of Personnel Division, National Postdoctoral Management Committee, the State Council Office of Rare Earth, Institute of Nuclear Energy Technology, Tsinghua University and the assistance of Chinese Society of Rare book was published "rare earth" The editorial department of the magazine and other relevant departments and leaders expressed their heartfelt thanks! The white pigeon researcher at the Deposit Institute of the Chinese Academy of Geological Sciences reviewed Chapter 2 and made valuable revisions. The Director of the Red Rare Office of the National Planning Commission’s Rare Earth Office took time out of his busy schedule to conduct a serious review of the book and proposed a lot of content. Invaluable opinions, I would like to express my sincere gratitude. The history of research and practice of rare earth beneficiation and rare earth extraction is not long, but many related papers have been published, which are relatively fragmented. It is not easy to derive a systematic book from these materials. Although the author wants to improve, it is inevitable that there are deficiencies, and experts and colleagues are urged to criticize and correct. Wang Dianzuo At the bank of Yanmen, Beijing August 1995 YKW08-20 mini crawler excavator is a collection of beautiful design, high configuration, good performance,low fuel consumption with wide operating ranges. It is suitable for loosing soil of vegetable greenhouse, municipal departments' landscape engineering, digging holes for tree planting in orchard, crushing concrete surface and sand-gravel mixing material, small space working sites etc. Adopting quick hitch that make you change working attachment easy and fast, and also can reduce maintenance and operating cost. Small Digger Hydraulic Bucket,Crawler Mini Excavator,cheap 2 ton small crawler excavator Henan YikYui Prospecting Machinery Co., Ltd , https://www.yikyui-rig.com
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