Recycling of bismuth oxides

OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 23 No. 3 2021 Fig. 2. Diffractograms of slags in the production of bismuth lead: a – experiment 4 ; b – experiment 3 ; 1 – Na 2 CaSiO 4 , 2 – Na 4 Mg 2 Si 3 O 10 , 3 – MgO, 4 – Pb, 5 – ZnS, 6 – PbS Ta b l e 3 Composition of the charge for reduction smelting of bismuth oxides Experiment Oxides, g Na 2 CO 3 , g SiO 2 , g Graphite, g 5 100 15 11 7 6 100 15 26 5 7 100 22 13 3 8 100 33 12,5 5 9 100 66 25 5 whereby the proportion of SiO 2 was maintained at 45–75 % wt. %, according to the liquidus temperature of 800–1100 ºС. The criterion which determined optimum conditions for the main operations of reduction smelting of bismuth oxides is the recovery ratio of the target metals in the metallic phase (Tables 4 and 5). Flux consumption is fundamental for smelt process performance. For experiments 5 and 7 the calcu- lated composition of slags, %: 42.4–78.2 Na 2 O; 21.8–57.6 SiO 2 , based on the diagram of the binary system state, should promote the phase separation, which in practice was not confirmed, demonstrating the absence of complete melting of the material. Additional information can be received by switching to the ternary system Na 2 O-SiO 2 -СаО, where imaging points of the assumed slag compositions, %: 67.8–70.2/33.8– 36.3 Na 2 О; 19.6–22.4/41.9–46.0 SiO 2 ; 9.9–10.2/20.2–21.8 СаО fall into areas with liquidus temperatures of 1200–1500 ºС, significantly higher than the target temperature.