Sponsored by: LMD Aluminum Committee
Program Organizer: C.G. Hendriks, Kaiser Aluminum and Chemical Corp.,9131 Interline Drive, Baton Rouge, LA 70809
Tuesday, PM Room: A6
February 6, 1996 Location: Anaheim Convention Center
Session Chairman: Dr. Milind Chaubal, Reynolds Metals Co., PO Box 9911, Corpus Christi, TX 78469
2:00 pm
HYDRARGILLITE AND BAYERITE: TWO POLYMORPHS OF ALUMINUM TRIHYDROXIDE: Mauryay M. Pyzalski, Wieslawa Mocun - Wczelik, Technical University of Mining and Metallurgy, Faculty of Ceramics and Material Engineering, Ave. Mickiewicz 30, A 3, 30-059, Cracow, Poland
The two following forms of the aluminum trihydroxide have been produced as a result extensive studies:the first one, obtained by Bayer and Grzymek method,the second one in a new Polish technology on a semi-technical scale. Some new modification were synthesized at different technical parameters of the process and they were subsequently investigated by use of several methods. The results thus obtained allow to characterize the properties of hydroxides. They also put a new light on their formation and polymorphism.
2:30 pm
THE STUDY ON REACTION OF RUTILE IN THE BAYER LIQUOR: Bi Shiwen, Yang Yihong, Li Dianfeng, Fu Gaofeng, Zhan Xin, Li Yan, Department of Nonferrous Metallurgy of Northeastern University, Shengyang 110006, China
Titania has a hindrance effect in digestion of diasporic bauxite, the forms of titania in diaspore are rutile and anatase. In the paper, the reaction of rutile in the Bayer digestion liquor is studied, and the effects of CaO, Na2OCAUST concentration and temperature on the reaction are probed into. The substance phase of the reaction product in difference condition are analyzed by using X-ray.
3:00 pm
EFFECT OF THE GRAINS MORPHOLOGY OF SPECIAL ALUMINA ON THE GREEN DENSITY OF MOULDERS: M. A. Wojcik, J. Sidor & O. Paiyz, Technical University of Mining and Metallurgy, Faculty of Materials Science and Ceramics, al. Mickiewicza 30, 30-059 Cracow, Poland
The successful fabrication of high alumina ceramics is a thorough preparation of the powders which depends on the various requirements of the different forming procedures. All of the aluminas used in these ceramics have defined ultimate crystal sizes, controlled grindability and green densities to ensure the very tight shrinkage tolerances which are critical for the spark plug production process. Production practices shows that alumina milling belong to very important unit operation. So, the effect of grains morphology of special alumina obtained after milling in rotary-vibration mill on the green density of moulders are presented in this paper. The granulation parameters (d50) of monodispersed product was selected according to its application in the production of sparking plugs.
3:30 pm
NEW TECHNOLOGY FOR ALUMINATE LIQUOR DECOMPOSITION: Dr. V. Abramov, Scientific and Technical Center "Reactor", Russia. G. Stelmakova, AO "Aluminiy", Russia
The basis for new technology for decomposition of aluminate liquor is the use of high seed ratio and countercurrent movement of liquid and solid phase with intensified mass transfer. The letter excludes the cycle of the main seed mass. To perform the process a new type of reactor without special mixing devices was created. It was named ATK "Sloy". Intensification of mass transfer makes it possible to shorten the period and to increase the degree of aluminate liquor decomposition. The new technology and the reactor are the result of the theory of nonpermanent mass transfer. The suggested technology was put to commercial tests on basis of a special experimental 100 m3 reactor. First the new technology was applied to aluminum hydroxide washing. The experiment showed that it was possible to use countercurrent mode of aluminum hydrate washing with water consumption on more than 1 cubic meter per ton. Later tests were conducted on decomposition of aluminate liquor with the initial Alumina/Caustic ratio of 3.2-3.3. The tests showed that using the new technology the decomposition period of aluminate liquor can be shortened significantly. Thus, it took 20 hours to increase the A/C ratio from 3.2 to 4.1, while usually the highest ratio reached within this period of time was 3.7. At present we started installation of an industrial 1000 m3 reactor "Sloy" to use the new technology of liquor decomposition.
4:00 pm BREAK
4:20 pm
THE EFFECT OF VARIOUS ADDITIVES ON BAYER DIGESTION OF DIASPORIC BAUXITE: Zhang Lun-he, Xu Qi-li, Wang Xiang-li, Zhengzhou Light Metal Research Institute, Henan, Shangjie District, Zhengzhou, China
In this paper, the effect of about ten kinds of additives on the Bayer
digestion of diasporic bauxite has been investigated. The experiment results
showed that mineral additives such as dolomite, chlorite, medicinal stone,
magnesite have a great influence upon the alumina extraction ratio of
diasporite and the scaling property of slurry. Nevertheless a great quantity of
additives must be used, the digestive results of bauxite is not satisfactory
(except dolime). So it is difficult to put into practice. In addition, we
treated lime and red mud or slurry with sodium-aluminate liquor to achieve
synthesis catalyzators on the definite conditions. Compared to the results when
lime being added, the alumina extraction ratio of diasporite increased 2-4%
when this kind of synthesis catalyzator being added under otherwise equal
conditions, and their molar ratio of digestion liquor (Na2O/AL2O3) decreased
0.03-.011. The effect is obvious and the technology is simple. The experiment
results approved that the synthesis catalyzator have industrial applied
value.
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