Abstract
We study the mechanism of alkane reduction of SnO2 for efficient low-temperature recovery of Sn from SnO2. Based on thermodynamic simulation results, we comparatively analyze the reduction behavior and the efficiency of SnO2 reduction by H2 and alkanes (CxHy=2x+2, 0 ≤ x ≤ 4). We found that alkanes (n·CxHy) with the higher nx generally complete the reduction of SnO2 (T100) at the lower temperature. Moreover, the T100 of the SnO2 reduction by alkanes (n·CxHy) was decreased from the T100 of pure hydrogen with the same amount of hydrogen atoms (n·Hy). We found that the concentration of a gas phase product mixture, the amount of the produced solid carbon, and the T100 complementary vary as a function of the nx and ny, the total amount of carbon and hydrogen atoms in the reducing gas phase molecules. Our results demonstrate a viability of the low temperature reduction method of SnO2 by alkanes for efficient recovery of Sn from SnO2, which can be applied for Sn recovery from Sn containing industrial wastes or Sn ores with economic value added that is held by the co-produced H2.
Highlights
We study the mechanism of alkane reduction of SnO2 for efficient low-temperature recovery of Sn from SnO2
We found that the H2/CO ratio increases if the methane reduction (MR) of SnOx proceeds under oxygen depleted conditions because the late released more oxophilic carbon takes up oxygen atoms from SnOx and gas phase H2O21
Because consistent two moles of H2 were used for SnO2 reduction to Sn, irrespective to the initial H2/SnO2 ratio, the decrease of the T100 is presumably due to the increased chemical potential of gas phase H2 upon increase in the H2/SnO2 ratio
Summary
We study the mechanism of alkane reduction of SnO2 for efficient low-temperature recovery of Sn from SnO2. Our results demonstrate a viability of the low temperature reduction method of SnO2 by alkanes for efficient recovery of Sn from SnO2, which can be applied for Sn recovery from Sn containing industrial wastes or Sn ores with economic value added that is held by the co-produced H2. In our previous report[20,21], we have designed a methane reduction (MR) method, an ecofriendly and simple versatile process of Sn recovery from SnOx containing industrial wastes, which can be potentially applied for Sn ore smelting. The extended release of two kinds of reducing agents from methane assures the versatility of the MR of SnOx and the increased economic efficiency[21] Another interesting finding was that the H2/CO ratio in the produced gas varies as a function of the CH4/SnO2 ratio. We found that the H2/CO ratio increases if the MR of SnOx proceeds under oxygen depleted conditions because the late released more oxophilic carbon takes up oxygen atoms from SnOx and gas phase H2O21
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