Recycling of bismuth oxides

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 3 2021 Conclusions 1. Combined melting of (1,100–1,150 ºС) bismuth oxides, sodium carbonate, silicon dioxide and carbon, taken in mass ratios of 100: (15–66) : (11–25) : (5–7), allows to convert 89.0–93.6 % of bis - muth and 99.5–99.7 % of lead from original oxides in to lead bismuth, containing 7.06–7.32 % Bi and 80.6–81.6 % Pb. The main phase of lead bismuth alloy is elemental lead. The obtained alloy can be further processed using conventional technologies for separation of bismuth and lead. 2. Increased consumption of flux results in enhanced yield of recyclable silicate slag with low content of target metals, %: 0.06–0.08 Bi; 1.23–1.81 Pb; 3.3–6.7 Zn; 0.6–1.2 Sb; 0.7–1.6 As; 0.5–1.2 Sn; 17.9–21.6 SiO 2 ; 22.5–36.7 Na 2 O; 3.9–7.4 MgO; 2.5–6.3 CaO, in which %: 1.4 Bi; 2 Pb; 47 Zn; 23 Sb; 33 Sn are con - verted. The main slag phases are Na 2 CaSiO 4 , Na 4 Mg 2 Si 3 O 10 , MgO, Pb, ZnS, PbS. 3. Combined melting (1,150 °С) of bismuth oxides, sodium carbonate, silicon dioxide and carbon, taken in mass ratios of 100:15:26:5 and 100:(33–66):(13–26):(5–7) makes it possible to release lead bismuth (the output is 61.8–74.0 % of the content of oxides) with the following composition, %: 7.1–8 Bi, 81.3–86.1 Pb, 0.08 Zn, 2.54 Sb, 0.76 As, 0.7 Sn, 0.99 Cu, 0.03 Ag. Rates of metals extraction to alloy are 95.6 % for Bi, 94.6 % for Pb, 0.8 % for Zn, 71.3 % for Sb, 30.4 % for Sn, 67.5 % for Cu. The main phase of the alloy is elemental lead. 4. Increased flux consumption (66 % Na 2 CO 3 , 25 % SiO 2 of Bi-oxides) makes it possible to obtain eas- ily fusible recyclable silicate slag (the output is 73 - 103 % of Bi-oxides) with the following composition, %: 0.03–1.20 Bi, 0.3–15.4 Pb, 5.9 Zn, 0.25 Sb, 0.99 As, 0.76 Sn, 0.02 Cu, 24.0 SiO 2 , 55.6 Na 2 O, 7.7 MgO, 6.9 CaO, 0.5 FeO. The following elements are recovered to slag, %: 6.6 Bi, 7.7 Pb, 78.2 Zn, 8.7 Sb, 41.0 Sn, 4.8 Cu. Na 2 CaSiO 4 , Na 4 Mg 2 Si 3 O 10 , MgO, Pb are the main phases. 5. The optimal mode of reduction smelting is determined for bismuth oxides (100 %) to obtain lead bismuth with %: 66 Na 2 CO 3 , 25 SiO 2 , 5–7 С. The process temperature is 1,150 ºС. The presence of impu - rities makes it necessary to introduce reagent treatment of lead bismuth into the technological scheme for processing of bismuth oxides. Decoppering and alkaline softening will make it possible to obtain a Pb-Bi alloy suitable for pyroelectrometallurgical processing. References 1. YukhinYu.M., MikhailovYu.I. Khimiya vismutovykh soedinenii i materialov [Chemistry of bismuth compounds and materials]. Novosibirsk, SB RAS Publ., 2001. 360 p. 2. Emsley J. The Elements. Oxford, Clarendon Press, 1991 (Russ. ed.: Emeli Dzh. Elementy . Moscow, Mir Publ., 1993. 256 p. ISBN 5-03-002422-0). 3. Smirnov M.P. Rafinirovanie svintsa i pererabotka poluproduktov [Lead refining and processing of semi- products]. Moscow, Metallurgiya Publ., 1977. 280 p. 4. Polyvyannyi I.R., Ablanov A.D., Batyrbekova S.A. Vismut [Bismuth]. Alma-Ata, Nauka Publ., 1989. 316 p. 5. Fedorov P.I. Khimiya i tekhnologiya malykh metallov. Vismut i kadmii [Chemistry and technology of small metals. Bismuth and Cadmium]. Moscow, MIHM Publ., 1986. 92 p. 6. Lu D., Jin Z., Chang Y., Sun S. Mechanism of debismuthizing with calcium and magnesium. Transactions of Nonferrous Metals Society of China , 2013, vol. 23, pp. 1501–1505. DOI: 10.1016/S1003-6326(13)62622-9. 7. Castle J.F., Richards J.H. Lead refining: current technology and a new continuous process. Advance in Extractive Metallurgy . London, The Institution of Mining and Metallurgy, 1977, pp. 217−234. ISBN 0900488379. 8. Hibbins S.G., Closset B., Bray M. Advances in the refining and alloying of low-bismuth lead. Journal of Power Sources , 1995, vol. 53, pp. 75–83. DOI: 10.1016/0378-7753(94)02007-P. 9. Betterton J.O., Lebedeff Y. Debismuthing lead with alkaline earth metals. Transactions of AIME , 1936, vol. 121, pp. 205−225. 10. Evers D. Debismuthing by the Kroll−Betterton process. Metallhuttenw , 1949, vol. 2, pp. 129−133. 11. Davey T.R.A. Debismuthing of lead. Journal of Metals , 1956, vol. 3, pp. 341−350. 12. Iley J.D., Ward D.H. Development of a continuous process for the fine debismuthizing of lead. Advance in Extractive Metallurgy . London, The Institution of Mining and Metallurgy, 1977, pp. 133−139. ISBN 0900488379. 13. Hancock P., Harris R. Solubility of calcium−magnesium−bismuth intermetallic in molten lead. Candian Metallurgy Quarterly , 1991, vol. 30, pp. 275−291.