Extraction of tin from hardhead by oxidation and fusion with sodium hydroxide


  • C Bunnakkha
  • C Jarupisitthorn


In this research work, the extraction of tin from tin-iron alloy or hardhead which is the intermediate product obtained during tin smelting was investigated. The hardhead containing 32.40 wt% Sn and 45.81 wt% Fe was ground to different sizes and oxidized at 500 to 800ºC for 1 to 6 hours to form SnO2 and Fe2O3. The results indicated that an increase in oxidation temperature decreased the required oxidation time. However using too high oxidation temperature (800ºC) resulted in sintering of the oxide product. In sodium hydroxide fusion stage, effects of fusion temperature, fusion time, NaOH quantity and oxide product size on tin leaching were investigated. By fusion the oxide product of -400+500 mesh size with 750 % excess NaOH at 700 C for 2 hours in order to convert SnO2 into soluble form of Na2SnO3,it was found that around 96 % of tin could be extracted by hot water (60ºC) while the iron oxide remained in residues.


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How to Cite

C. Bunnakkha and C. Jarupisitthorn, “Extraction of tin from hardhead by oxidation and fusion with sodium hydroxide”, J. Met. Mater. Miner., vol. 22, no. 1, Jun. 2012.



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