Molybdenum Production by the Electrochemical Reduction of Solid Molybdenum Compounds

Öz

The electrochemical reduction of molybdenum compounds; CaMoO4 and MoS2, which form the cathode of the cell by being attached to a current collector, was investigated. Molten CaCl2-NaCl salt solutions were used as the electrolyte. The compositions and morphologies of the reduced samples were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. The examinations showed that it is not possible to produce Mo without loss by the electrochemical reduction of CaMoO4. The aforementioned compound has around 1.9% solubility in eutectic CaCl2-NaCl salt solution at 750oC. Formation of Mo was not observed at 600oC where the solubility was relatively not important. On the other hand, production of molybdenum from MoS2, which is the most important Mo mineral found in nature, was accomplished successfully. Pure molybdenum powder was obtained by the dissolution of calcium products found in the reduced samples in dilute acid solution.

Anahtar Kelimeler

• : Electrochemical reduction,Electrodeoxidation,Mo,CaMoO4,MoS2

Katı Molibden Bileşiklerinin Elektrokimyasal İndirgenmesiyle Molibden Üretimi

Öz

İletken bir telin ucuna tutturulmak suretiyle hücrenin katodunu oluşturan, molibden bileşikleri; CaMoO4 ve MoS2’nin elektrokimyasal yöntemlerle indirgenmesi incelenmiştir. Elektrolit olarak, erimiş haldeki CaCl2-NaCl tuz çözeltileri kullanılmıştır. İndirgenen örneklerin içeriği ve morfolojisi X-ışınları kırınımı (XRD) ve taramalı elektron mikroskobu (SEM) analizleri aracılığıyla belirlenmiştir. Yapılan incelemeler CaMoO4’ten elektrokimyasal indirgeme yöntemiyle kayıp vermeksizin Mo üretmenin mümkün olmadığını göstermiştir. Söz konusu bileşik ötektik CaCl2-NaCl çözeltisi içerisinde 750oC’de yaklaşık %1,9 civarında çözünürlüğe sahiptir. Çözünürlüğün nispeten önemsiz olduğu 600oC’de ise Mo oluĢumu gözlemlenmemiştir. Molibdenin doğadaki en önemli minerali olan MoS2’den elektrokimyasal indirgeme yöntemiyle Mo üretimi ise 750 oC’de başarıyla gerçekleştirilmiştir. İndirgenen numunedeki kalsiyum bileşiklerinin seyreltik asit çözeltisinde çözündürülmesi ile saf Mo tozu elde edilmiştir.  

Anahtar Kelimeler

• Elektrokimyasal indirgeme,Elektrodeoksidasyon,Mo,CaMoO4,MoS2

Kaynakça

1. 1. Gupta, C.K., 1992. Extractive Metallurgy of Molybdenum. CRC Press.
2. 2. Chen G.Z., Fray D.J., Farthing T.W., 1999. Patent No. WO1999064638 A1.
3. 3. Chen GZ, Fray. D., Farthing T.W., 2000. Direct Electrochemical Reduction of Titanium Dioxide to Titanium in Molten Calcium Chloride. Nature, 407(6802): 361-4.
4. 4. Gordo, E., Chen, G.Z., Fray, D.J., 2004. Toward Optimisation of Electrolytic Reduction of Solid Chromium Oxide to Chromium Powder in Molten Chloride Salts, Electrochimica Acta, 49, 2195-2208.
5. 5. Ergül, E., Karakaya, Ġ., Erdoğan, M., 2011. Electrochemical Decomposition of SiO2 Pellets to Form Silicon in Moltn Salts, Journal of Alloys and Compounds, 509, 899–903.
6. 6. Han, W.K., Choi, J.W., Hwang, G.H., Hong, S.J., Lee, J.S., Kang, S.G., 2006. Applied Surface Science, 252, 2832.
7. 7. Chen, G.Z., Fray, D.J., 2000. in: Progress in Molten Salt Chemistry 1, pp. 157-162.
8. 8. Chen, G.Z., Fray, D.J., 2001. in: TMS Light Metals, New York, pp. 1147-1152.

9. 9. Yan, X.Y., Fray, D.J., 2002. Metallurgical and Materials Transactions B, 33B, 685.
10. 10. Abdelkader, A.M., Daher, A., El-Kashif, E., 2007. Metallurgical and Materials Transactions B, 38B, 35.
11. 11. Erdoğan M., Karakaya Ġ., 2010. Electrochemical Reduction of Tungsten Compounds to Produce Tungsten Powder, Metall. Mater. Trans. B, 41B, 798-804.
12. 12. Erdoğan M., Karakaya Ġ., 2012. On the Electrochemical Reduction Mechanism of CaWO4 to W Powder, Metall. Mater. Trans. B, 2012, 43B, 667.
13. 13. Karakaya Ġ., Erdoğan M., 2007. Türk Patent Enstitüsü, TR, 07197 B.
14. 14. Karakaya Ġ., Erdoğan M., 2012. Russian Agency for Patents and Trademarks, RU 2 463 387 C2, 2012.
15. 15. Karakaya Ġ., Erdoğan M., 2013. Canadian Intellectual Property Office CA 2 703 400 A1.
16. 16. Okyay, V., 2012. Türkiye’nin Son Gözdesi Molibden, Madencilik Türkiye, 104-110.
17. 17. Li, G., Wang, D., Jin, X., Chen, G.Z., 2007. Electrolysis of Solid MoS2 in Molten CaCl2 for Mo Extraction without CO2 Emission, Electrochemistry Communications, 9, 1951–1957.