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  Proceedings of the Estonian Academy of Sciences. Chemistry

 

ISSN 1406-0124

Published since 1952 to 2007

Proceedings of the Estonian Academy of Sciences. Chemistry

 

ISSN 1406-0124

Published since 1952 to 2007

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Calcium–aluminothermal production of niobium and mineral composition of the slag; 142-156

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Authors

Valeri Gorkunov, Rein Munter

Abstract

The process of niobium pentoxide calcium–aluminothermal reduction in pilot plant and full scale conditions was studied at Silmet JSC, Estonia. In the paper the construction and operating parameters of the pilot plant shaft melting furnace and the composition of raw materials mixture as well as of the product (niobium ingot) are described. The optimum ratio of Ca/Al to obtain the best quality niobium ingot was revealed in pilot plant melting tests, and the results of analyses of the mineral and phase composition of the slag are presented. Addition of metallic Ca to the raw materials mixture with 10% excess enabled to reduce the Al content in ingot to 4.4% and increase the Nb content > 90%. In the optimum conditions of the reduction process a slag with the composition of 3CaO·5Al2O3 is formed. Also different niobium containing oxides and metallic phases may be present in the slag. The results obtained enable to optimize the niobium production process and to elaborate an effective protective layer for the graphite facing of the furnace as well as to make some suggestions for possible utilization of the waste slag in the building materials industry.

Keywords

rare metals, niobium, metallothermy, alloys production, waste slag.

References

 1. http://www.silmet.ee 08.07.2007

 

 2. http://www.giredmet.ru/obzory/rare_2006.html (Production of niobium and market in the USA and in the world). 09.10.2006 (in Russian).

 3. Berg , M. , Parshin , A. & Plotnikov , V. Method of metallic niobium production. Patent USSR. No. 134623.1979 (in Russian).

 4. Gorkunov , V. , Berg , M. & Parshin , A. High temperature processes of removal of slag and graphite from niobium. Patent USSR. No. 233207. 1986 (in Russian).

 5. Pliner , J. & Ignatenko , G. Reduction of Oxides with Aluminium. Metallurgy , Moscow , 1967 , 120–123 (in Russian).

 6. Plotnikov , V. , Parshin , A. & Gorkunov , V. Elaboration of calcium–alumothermal method for tantalum production and alloys on the basis of niobium and tantalum. Report VNIIHT. Moscow , 1984 (in Russian).

 7. Volskii , A. & Sergievskaya , E. Theory of Metallurgy. Metallurgy , Moscow , 1968 (in Russian).

 8. State Diagrams of Twin Metallic Systems. Handbook , Vol. 3 , No. 1 , pp. 706 , 737 , 806. Engineering , Moscow , 2001 (in Russian).

 9. Clark , J. & Macquarrie , D. Handbook of Green Chemistry and Technology. Blackwell Publ. , UK , 2002 , 434.

10. Zelikman , A. , Korshunov , B. & Elyutin , A. Niobium and Tantalum. Меtallurgy , Мoscow , 1990 , 120–125 (in Russian).

11. http:// www.tulane.edu/~sanelson/eens211/mineral_chemistry.htm

12. Certificate of the analysis No. 200709/UK. Centre for Materials Research , Tallinn University of Technology , 11.06.2007.

13. Quality Certificate No. 0012870. Silmet JSC , 18.05.07.

14. Schlackatlas. Stahleisen Verlag GmbH , Düsseldorf , 1981.

15. Gorkunov , V. & Munter , R. Possibilities of utilization of waste slags from niobium production. In Abstracts of International Conference EcoBalt-2007. Riga , May 10–12 , 2007. Intego Plus , Riga , 2007 , 124–128.

 
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Current Issue: Vol. 56, Issue 4, 2007




Publishing schedule:
No. 1: 20 March
No. 2: 20 June
No. 3: 20 September
No. 4: 20 December