Alkali Metallurgy
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Research Center of Alkaline Process Metallurgy (RCAPM), formerly known as Institute of Alumina and Ceramic, has been constantly dedicating to the talent training and technical progress in alumina refinery since 1952. Presently, research areas extend to the green extraction of chromate and tungstate, as well as the comprehensive utilization of resources and environmental protection.

RCAPM consists of a strong teaching and research team, including 4 professors (Dr.Xiaobin LI, Dr.Zhihong PENG, Dr.Guihua LIU and Dr.Qiusheng ZHOU), 1 lecturer (Dr.Tiangui QI) and more than 30 postgraduates. RCAPM has accomplished over 90 research projects, published 190 papers and applied for/issued over 30 invention patents. And up to now, 13 innovative technologies are successfully applied in/at alumina refineries, chromate plants and other enterprises.

Research Fields and Interest

Theory and technique of metallurgy in alkaline system

To save/conserve energy, increase product quality and simplify extractive process, we conduct research on the element behavior and reaction mechanism in alkaline system, and committed to develop new metallurgical technologies of aluminum, tungsten, vanadium, chromium and molybdenum.

Crystallization process

To increase product quality and control the morphology of precipitates, we conduct research on the mechanism of nucleation, agglomeration, growth and breakup of crystals formed from solution.

Interface properties

To intensify metallurgical process, simplify process and discover new surficial property of compounds, we study the variation of interfacial properties and determine the interface reaction mechanism.

Comprehensive utilization of resources and environmental protection

To make full use of resources and protect environment, we are to study the technology for comprehensive utilization of alumina-bearing substances, and chromium-bearing slag.

Techniques in industrial application

1)Intensified Sintering process for alumina extraction from diasporic bauxite

An intensified sintering process is developed to obtain new sinter, concentrated green liquor and high quality alumina. Compared to the traditional sintering process, the output of the kiln increases by over 70%, energy consumption decreases by 40%, and soda loss reduces by 40%.

2Intensive desilication by adding calcium hydrate carbonate-aluminate

Silicate-bearing aluminate solution is further purified by adding calcium hydrate carbonate-aluminate. Compared to the traditional desilication process with the addition of lime, the addition of lime reduces by more than 40%, alumina loss reduces by more than 40%, and alumina concentration of desilicated solution raises 2g/L.

3Two-stage desilication technology under atmospheric pressure for the sintering process

Both the first desilication and the second desilication are carried out under atmospheric pressure, the mass ratio of alumina to silica(A/S ratio) reaches over 300 in the first desilication, and over 600 in the second desilication. Compared to the traditional desilication process, 60% energy is saved, and alumina loss reduced by 40%.

4 Scale retarding technology in the evaporation of spent liquor

A new scale retardant is prepared to prevent scale from deposition on surface of equipment. The washing interval with water prolongs from 3~5 days to more than 50 days, and about 2% energy is saved in comparison with the evaporation without retardant addition,

5Preparation of sandy alumina by sintering process

A new technology, including seed preparation, control of precipitation ratio and temperature scheme, is developed. Compared to the flour-shaped alumina from the traditional sintering process, sandy alumina( -45μm<8% ,+150μm ~0%,d0.5 70~80μm) is obtained after the new carbonation process is employed.

6Removal of sodium oxalate in aluminate solution

A new technology, including formation of calcium oxalate and reaction of calcium oxalate with aluminate ion, is developed. Compared to the other methods adopted in alumina refineries, the transformation of calcium oxalate to calcium hydrate aluminate is inhibited/limited significantly, the required amount of lime reduces by 50%, and alumina loss decreases by 50%.

7) Preparation of ultrafine alumina trihydrate with high whiteness in concentrated aluminate solution

Unltrafine alumina trihydrate powders with d0.5 1.3μm, 5μm or 10μm is prepared by seeded precipitation when the purified concentrated aluminate solution (Al2O3>165g/L) is employed. The whiteness of the product is greater than 96%, and oil adsorption is less than 42 ml/100g.

8) Surface modification for fine alumina trihydrate powders

After surface modification for ~2μm alumina trihydrate powder, oil adsorption of modified alumina trihydrate <35ml/100g, active ratio>99% and the contact angle>100glycerin.

9) Removal of aluminate ion from sodium chromate solutions by neutralization

A new neutralization process has been developed in comparison with the traditional process. Water content of aluminum-bearing residue decreases from ~80% to ~40%, chromate loss reduced from ~20% to less than 0.5%. Moreover, aluminum-bearing residue can be readily separated by belt filter due to its good settlement property.

10) Comprehensive utilization of aluminum-bearing residue in chromate production

The aluminum-bearing residue from chromate solution is used to produce coarse alumina trihydrate. Chromate attached to the aluminum-bearing residue reenters production system. Consequently, no toxic residue is remained.

11)  Comprehensive utilization of vanadium-bearing residue in chromate production

A new technology is adopted, chromate is recovered, and V2O5 is prepared from vanadium-bearing residue formed in purification of sodium chromate solution.

12) Intensified desilication process of aluminate solution from the sweetening process

Compared to the traditional process, A/S mass ratio in solution increases from ~160 to ~250, benefiting seeded precipitation and evaporation, restraining the formation of scale.

13) Database for alumina production and calculation software of mass balance in alumina production

Selected publications

[1] Xiaobin Li, Shunwen Yu, Nan Liu et al. Dissolution behavior of sodium titanate in sodium aluminate solutions at elevated temperatures. Hydrometallurgy. 2014,147~148: 73-78.

[2] Gui-hua LIU, Peng WANG, Tian-gui QI et al. Variation of soda content in fine alumina trihydrate by seeded precipitation. Trans. Nonferrous Met. Soc. China .2014,24(1):243~249.

[3] Xiao-bin LI, Li YAN, Dong-feng ZHAO et al. Relationship between Al(OH)3 solubility and particle size in synthetic Bayer liquors. Trans. Nonferrous Met. Soc. China.2013,23(5):1472~1479.

[4] Xiaobin Li, Danqin Wang, Qiusheng Zhou et al. Influence of magnetic field on the seeded precipitation of gibbsite from sodium aluminate solution. Minerals engineering. 2012, 32: 12–18.

[5] PENG Zhi-hong, CHEN Yan-hu, ZHOU Qiu-sheng et al. Effect of fluidized separating-washing of red mud on secondary reactions of leached slurry with high alumina concentration. Journal of Central South University (Science and Technology). 2012, 43(6):2036-2042.(in Chinese)

[6] Zhou Qiusheng, Li Xiaobin, Li Jianpu, et al. Direct Hydrothermal Precipitation of Pyrochlore-Type Tungsten Trioxide Hemihydrate from Alkaline Sodium Tungstate Solution. Metallurgical and Materials Transactions B. 2012, 43(2): 221-228.

[7] ZHOU Qiu-sheng, NIU Fei, WANG Jun-e, et al. Influences of impurities of ferrous oxide and aluminum oxide on oxidation rate of trivalent chromium and its mechanism. The Chinese Journal of Nonferrous Metals.2012, 22(5): 1503-1508.(in Chinese)

[8] LI Xiaobin, YAN Li, ZHOU Qiusheng, et al. Thermodynamic model for equilibrium solubility of gibbsite in concentrated NaOH solutions. Trans. Nonferrous Met. Soc. China . 2012, 22(2): 447-455.

[9] Qi Tiangui, Liu Nan, Li Xiaobin, et al. Thermodynamics of chromite ore oxidative roasting process. Journal of Central South University of Technology. 2011, 18: 83-88.

[10] Li Xiaobin, Wang Danqin, Zhou Qiusheng, et al. Concentration variation of aluminate ions during the seeded precipitation process of gibbsite from sodium aluminate solution. Hydrometallurgy. 2011, 106(1): 93-98.

[11] Xiaobin Li, Qiusheng Zhou, Haoyu Wang et al. Hydrothermal formation and conversion of calcium titanate species in the system Na2O–Al2O3–CaO–TiO2–H2O. Hydrometallurgy. 2010,104(2):156-161.

[12]Qiusheng Zhou, Dianjun Peng, Zhihong Peng et al. Agglomeration of gibbsite particles from carbonation process of sodium aluminate solution. Hydrometallurgy. 2009,99(3-4):163-169.

[13]LI Xiao-bin; QI Tian-gui; New technology for comprehensive utilization of aluminum-chromium residue from chromium salts production. Trans. Nonferrous Met. Soc. China. 2008,18(2):463~468.

[14] LI Xiaobin, TAN Peilong, LU Weijun et al. Sintering process between kaolinite and alkali lime. Journal of the Chines Ceramic Society. 2006,34(4):422~426.(in Chinese)

[15] LI Xiao-bin, LU Wei-jun, FENG Gang-tao et al. The applicability of Debye-Hückel model in NaAl(OH)4-NaOH-H2O system. The Chinese Journal of Process Engineering. 2005,5(5):525~528.

[16] LI Xiaobin , LIU Xiangming , LIU Guihua et al. Study and application of intensified sintering process for alumina production. The Chinese Journal of Nonferrous Metals. 2004,14(6): 1031-1036.(in Chinese)

[17] LIU Gui-hua, LI Xiao-bin, PENG Zhi-hong et al . Behavior of calcium silicate in leaching process. Trans. Nonferrous Met. Soc. China. 2003,13(1):213-216.

[18] LI Xiao-bin. Intensifying digestion of diaspore and separation of alumina and silica. Trans. Nonferrous Met. Soc. China . 2003,13(3):671-677.

[19] PENG Zhi-hong, LI Xiao-bin, GOU Zhong-ru et al. Impurity Na2O in carbonization precipitation from sodium aluminate solution with high Al2O3 concentration. The Chinese Journal of Nonferrous Metals.2002,12(6): 1285-1289.(in Chinese)

[20]Li Xiaobin, Zhou Qiusheng. Preparation of Zirconia-alumina powder by co-precipitation. Trans. Nonferrous Met. Soc. China. 2000,10(2):257~261.

[21] Liu Guihua, Li Xiaobin, Peng Zhihong et al. Formation and solubility of potassium aluminosilicate. Trans. Nonferrous Met. Soc. China. 1998,8(1), 120~123.

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