The theory and technology of efficient utilization of aluminum resources and preparation of high-performance aluminum materials led by Professor Zhong Jue of Central South University won the first prize of national scientific and technological progress in 2007, which broke through the technical obstacle of low-grade aluminum resources mining and refining efficiency and greatly improved the guarantee period of bauxite resources in China. The project is mainly aimed at the shortage of aluminum resources in China, the failure of advanced aluminum materials to meet the major strategic needs of the country, the high energy consumption and high pollution in the development of aluminum metal. At present, * * * has obtained 67 invention patents, 7 complete sets of technologies and 16 kinds of high-performance aluminum alloy materials and components. Bayer process invented by this project can economically utilize medium-low grade bauxite which accounts for 80% of China's bauxite reserves, and alleviate the contradiction that aluminum resources can't meet the needs of industrial development at present. However, technologies such as the preparation of oxidation-resistant low-resistance carbon anode can save energy and reduce emissions by more than 10% in the smelting process, and the annual power saving exceeds10 billion kW·h (Zhong Jue, Central South University, a major technological innovation in the development of aluminum industry in China, China Aluminum Industry, No.07, No.03, 2007). Central South University News Network, "Scientific Research Achievements of Central South University Solve Three Difficult Problems in Domestic Aluminum Industry", March 3, 20081)
Gu, Yin, Liu, Wu, etc. Chinalco invented a method for producing alumina from low-grade bauxite, and applied for a patent on July 2, 2007, with the patent number of 200710118667. And relates to a method for producing alumina by treating low-grade bauxite by Bayer process. Characterized in that in the Bayer process adopted, the leaching process is that dealuminated slag is added as an additive instead of lime to medium-low grade bauxite for Bayer leaching; After backwashing, the leached red mud is mixed with circulating alkali liquor, and lime is added for leaching reaction, and then the separated slurry is discharged. The obtained solution is partially backwashed to leach red mud by Bayer process, and then sent to Bayer process system for alkali supplementation, and part of it is added with lime for reaction to obtain dealuminated slag and circulating alkali liquor, which are used for wet treatment of red mud by Bayer process. Calcium aluminate hydrate from dealuminated slag is added to Bayer process for leaching instead of lime. The method of the invention is an all-wet process, which has the advantages of simple process, low energy consumption, low alkali consumption, high alumina recovery rate, high resource utilization rate, low red mud discharge and easy comprehensive utilization.
In 2004, China Nonferrous Metals Industry Association organized a project appraisal meeting of "New Technology of Stage Grinding-Enhanced Collecting and Flotation for Low-grade Bauxite in Shanxi" jointly completed by Zhengzhou Research Institute, Shanxi Branch, Zhongzhou Branch and Chinalco Central South University. Experts attending the meeting listened to the report of the research group and reviewed the appraisal data provided by the project team. Experts believe that the project takes low-grade bauxite in Shanxi as the research object, systematically carries out laboratory and industrial test research, and achieves the expected goal, with the following innovations: the industrial test of direct flotation desilication of low-grade diaspore bauxite in Shanxi was completed for the first time, forming a "new process of bauxite stage grinding-enhanced collection and rapid coarse particle selection". The industrial test runs stably. When the Al-Si ratio of raw ore is 4.4~5. 1, the concentrate yield is 72.73%~77.78%, the Al-Si ratio is 9.70~ 10.53, and the alumina recovery rate is 8 1.07%~85.42%. Adopting stage grinding to improve selective crushing can make low-grade bauxite better realize monomer dissociation, improve the particle size distribution characteristics of ground minerals, reduce the sliming of silicate minerals, and help improve flotation indexes and sedimentation and filtration performance of products; The mixed efficient collector developed has a strong collecting effect on diaspore, which improves the selectivity of flotation separation of aluminosilicate minerals and the recovery rate of target minerals. The rapid cleaning process of coarse particles significantly optimizes the particle size distribution of concentrate, improves the flotation index, shortens the process and reduces consumption; Through the study of tailings sedimentation and dry storage technology, suitable flocculants and dehydrating agents were selected, which provided technical basis for bauxite beneficiation production, tailings sedimentation and dry storage. This process solves the technical bottleneck of the utilization of mineral processing backwater and realizes the full utilization of backwater. Experts believe that this project provides an economical and feasible beneficiation technology for producing alumina from low-grade diaspore bauxite with the Al-Si ratio of 4~5 in Shanxi by Bayer process, and the overall technology has reached the international leading level. The research results of this project have laid a foundation for the beneficiation production of low-grade bauxite in Shanxi, and have wide application value. (building materials network, China, Shanxi low-grade bauxite stage grinding-enhanced collection flotation new technology project passed the appraisal, 2006-8-15; New Technology of Alumina Production, China Aluminum Industry, No.07, 2007, 103).
Yin, Fan Weidong and Liu Ruxing of Chinalco Co., Ltd. applied for a patent on July 12, 2007. The patent application number is 200710118680.7 "A method for extracting alumina from low-grade bauxite", which relates to a technological method for extracting alumina from low-grade bauxite and comprehensively utilizing residues after extracting alumina. Characterized in that ammonium sulfate is added into low-grade bauxite for sintering, the obtained sintered material is dissolved out to obtain a solution containing ammonium aluminum sulfate, and solid ammonium aluminum sulfate is obtained by crystallization, and then the solid ammonium aluminum sulfate reacts with ammonia gas to obtain aluminum hydroxide and ammonium sulfate, and the solid aluminum hydroxide is obtained by washing and filtering, and the alumina product is obtained by roasting; After evaporation, the ammonium sulfate entering the liquid phase continues to be recycled. In the method of the invention, the ammonium sulfate used in the process is weakly acidic, has little corrosiveness to equipment, can be recycled, and the whole process is easy to be industrialized, and the obtained residue is less, which is beneficial to the comprehensive utilization of the residue after extracting alumina. (China National Intellectual Property Administration, People's Republic of China, 2007).
From 1998, Henan Rock and Mineral Testing Center began to contact the National Institute of Mineral Resources of Ukraine for friendly talks on desilication of bauxite in Henan Province. 1June, 1999, the experimental research work of removing silicon dioxide from low-grade bauxite in Henan province by Ukrainian microbial technology reached an intention. From September, 2000 to February, 2000, we confirmed the cooperative relationship between the two sides in bauxite desilication in Henan Province and signed a scientific and technological cooperation agreement. The representative bauxite sample, Xiaoguan bauxite sample, was extracted from Zhengzhou Aluminum Factory by Henan Rock and Mineral Testing Center. After crushing and reducing, it was used as experimental sample, chemical analysis sample and mineral analysis sample. The study of the material composition of the sample shows that the mineral color is gray and dark gray, and it is dense aphanitic sandstone. According to the results of X-ray diffraction and differential thermal analysis, its main mineral components are diaspore, muscovite and pyrophyllite. According to chemical analysis data, the mineral composition of bauxite is estimated as follows: diaspore 59%, muscovite-chlorite, kaolinite (mainly muscovite) 20.5%, pyrophyllite 16.0%, calcite 1.8%, pyrite 0.2%, titanium mineral (such as anatase) aluminum. 65438 00% silica exists in pyrophyllite and 7.8% in muscovite. The key to the cooperative utilization of biological desilication technology between China and Ukraine is the separation and culture of active microorganisms and the adaptability of microorganisms to raw ore. In the process of biological desilication of bauxite, the crystal lattice of aluminosilicate is destroyed by photosynthetic autotrophic bacteria-silicate bacteria, and silicon is transformed into dissolved state. Using strains imported from Ukraine and self-cultured strains, the desilication ability of five artificially cultured and three naturally cultured silicate bacteria strains was studied, and two strains with the strongest activity in diaspore bauxite were screened out. In the initial stage, the desilication ability of silicate bacteria is quite low. It shows that the mineral composition of bauxite is complex and difficult to separate. In the subsequent strengthening process, continuous and gradual adaptive measures are adopted to apply bacteria to the studied raw ore. After more than two years of experiments, the initial mass fraction of silica in bauxite was successfully reduced to 8.8%. The mass fraction of Al2O3 in bauxite increased from 62.5% to 74. 1%. In the aspect of studying the possibility of microbial leaching of silicon under the action of biological reactants, 57.4% of SiO2 _ 2 is leached with the obtained known biological reactants, and the Al/Si ratio reaches 8. 1, which shows that the microbial leaching process of silicon is quite effective, and the Al/Si ratio is close to the standard index. The experiment shows that, after ignoring the influence of physical and chemical factors such as pH, potential, bacterial concentration and nutrient mass fraction on the efficiency of microbial desilication, with the help of silicate bacteria, the mass fraction of 58.3% SiO2 _ 2 can be reduced to the corresponding percentage, and the aluminum-silicon ratio of bauxite can be increased from 3.5 to 8.4, so it is feasible to adopt microbial desilication process. The experimental research was guided by Wang Dianzuo, vice president of China Academy of Engineering, and highly praised by many experts such as Academician Zhong Jue and Academician Liu. It is considered as a new technology for desilication of bauxite, which initiated the application of microbial technology in desilication of bauxite. (China International Talent Exchange Conference, New Progress of Sino-Ukrainian Cooperation in Promoting Microbial Removal of Silica from Bauxite, July-September 2008)