This paper deals with gold extraction from a refractory concentrate by chlorine leaching.The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentra...This paper deals with gold extraction from a refractory concentrate by chlorine leaching.The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentration.The oxidized material is treated by leaching with brine.After gold adsorption/reduction onto activated carbon,iron and base metals can be precipitated by NaOH.Roasting tests show the necessity to carry out a thermal pre-treatment at least at 550°C to obtain a reduction of sulfur and mercury in the material(50%and 90%,respectively).Highest gold extraction yield(around 93%)is obtained in the leaching test performed with material sample treated at 650°C.This result confrms the necessity to optimize the thermal pre-treatment to improve Au recovery and to reduce chlorine consumption.A comparison with conventional cyanidation confrms that chlorination could be an useful alternative:in fact,gold extraction yield is quite low:57%in non-pre-treated material and 25%in pre-treatment material.展开更多
The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Di...The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Distilled water,citric and sulphuric acid were preliminarily investigated,thus two further full factorial systems entailing H2SO4–H2O2and H2SO4–H2O2–Fe3+were tested.The preliminary experimental results showed that0.1 mol·L-1H2SO4solution extracted 100%of Cu,Fe and Zn,whereas citric acid leached 100%of Zn and Pb,59%of Fe and 62%of Cu;whereas,H2SO4–H2O2and H2SO4–H2O2–Fe3+(Fenton's)leaching media showed that Cu,Fe and Zn can be extracted simultaneously and completely from the ASR ashes before final disposal.展开更多
文摘This paper deals with gold extraction from a refractory concentrate by chlorine leaching.The process considers a pre-treatment of refractory materials by low temperature oxidation carried out with low oxygen concentration.The oxidized material is treated by leaching with brine.After gold adsorption/reduction onto activated carbon,iron and base metals can be precipitated by NaOH.Roasting tests show the necessity to carry out a thermal pre-treatment at least at 550°C to obtain a reduction of sulfur and mercury in the material(50%and 90%,respectively).Highest gold extraction yield(around 93%)is obtained in the leaching test performed with material sample treated at 650°C.This result confrms the necessity to optimize the thermal pre-treatment to improve Au recovery and to reduce chlorine consumption.A comparison with conventional cyanidation confrms that chlorination could be an useful alternative:in fact,gold extraction yield is quite low:57%in non-pre-treated material and 25%in pre-treatment material.
文摘The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Distilled water,citric and sulphuric acid were preliminarily investigated,thus two further full factorial systems entailing H2SO4–H2O2and H2SO4–H2O2–Fe3+were tested.The preliminary experimental results showed that0.1 mol·L-1H2SO4solution extracted 100%of Cu,Fe and Zn,whereas citric acid leached 100%of Zn and Pb,59%of Fe and 62%of Cu;whereas,H2SO4–H2O2and H2SO4–H2O2–Fe3+(Fenton's)leaching media showed that Cu,Fe and Zn can be extracted simultaneously and completely from the ASR ashes before final disposal.
