SIPS 2018

DETAILLED PROGRAM OVERVIEW

Alternative Aluminium Production Technologies
Vasiliy Kryukovskiy¹;
¹RUSAL, Moscow, Russian Federation;
PAPER: 128/Non-ferrous/Regular (Oral)
SCHEDULED: 11:45/Tue./Pontal (50/2nd)

ABSTRACT:
A successful development of the Bayer-Hall-Héroult process (pot amperage-600kA, power consumption-12,500kWh/t, and current efficiency-95%) during the past 20 years has been significant for pre-baked anode smelting efficiency, which is close to peak performance. It is obvious that under the circumstances, even the slightest increase of any indicator requires such huge costs that they might never be recouped, considering growing prices of raw materials, energy, and transportation. At the same time, there are pending issues with greenhouse gas pollution and contamination of land and water with red mud and spent pot lining. In this environment, it is logical to address well-known technologies which have not been practiced for various reasons. Among them are: low-consumption and bipolar electrodes[1], electrolysis of aluminum chloride through chlorination of non-bauxite aluminum containing ore (Toth Aluminum Corporation)[2], carbothermal production of alumosilicic alloys from sillimanite, caoline and others. The current studies have proven that the main problem with commercialization of the low-consumption electrodes is that it has been tested on a classic pot design with horizontal carbon anodes, whereas changes in mass and heat transfer require a new pot design, alumina, and current feeding as well as MHD control. Unfortunately, sporadic tests on cells with vertical and bipolar electrodes, with low-melting bath and alumina suspensions have not become pilot. The same happened to electrolysis of aluminum chloride: alumina chlorination issues unsolved by Alcoa and All-Russian Aluminum and Magnesium Institute (VAMI) stopped further development of the advanced technology right when Toth Aluminum Corporation announced and Fluor Daniel confirmed a technical feasibility of the aluminum chloride production by chlorination of low-quality alumina containing ore (caoline, sillimanite and others). This problem remained unsolved in the Alcoa-VAMI technology. In this regard chlorination of high-silicon ore and smelting of chloroaluminate is an interesting process researched by Academy Fellow А. Marakushev [3]. The carbothermal process developed by VAMI to produce alumosilicic alloys was used in the USSR in 1980s [4]. The advantages are as follows: there is no expensive alumina refining and caustic/ acid mud stacking in the cycle; there are no costs on production of expensive electrode materials; there are no transportation costs associated with bauxite mining, delivery and processing, which reduces aluminum cash cost; CAPEX on construction of the alumosilicic alloy carbothermal area is minimal compared to costs on construction of alumina production and smelting area with the equal capacity. The use of the carbothermal process to produce primary alumosilicic alloy will help build up aluminum and aluminum-based production, and will reduce emissions significantly. RUSAL, one of the largest aluminum companies in the world, addresses these and other subjects by investing hundreds of millions of dollars every year into the environment and acting as a global leader in the reduction of GHG emissions and production of low carbon aluminum. The report will cover projects RUSAL is implementing or has implemented in relation to topical issues associated with alternative production of aluminum and value-added products, including scandium alloys, mud stacking and aluminum waste processing.

References:
[1] Galasiu I., Galasiu R., Thonstad J. Inert anodes for aluminium electrolysis. 1-st edition, Aluminium-Verlag, Germany: 2007. 209 p.
[2] Toth Аluminium Corp., Patent USA 4514373A, 1983.
[3] Маrакushеv А.А. и др. ЕР 0611837,1992.
[4] Saltykov A.M., Baymakov A.Y. Development of electro thermal aluminium-silica alloys production. Zvetnye Metally, N7, 2003.