Alkaline Sodium Sulfide Leaching of Antimony from High Antimony Gold Concentrates and Gold-Inhibition Mechanism AITranslate
Abstract AITranslate
With the gradual exhaustion of easy-to-treat gold mineral resources，gold production enterprises are pressured to utilize the refractory gold concentrate with high impurity contains arsenic and antimony as alternate. Since golds in these refractory ores are usually deposited with other metal sulphides and silicates，and mostly embedded in stibnites，pyrites and arsenopyrites，it is hard to achieve effective gold extraction by conventional wet process. Therefore，efficiently matte smelting capturing-Au technology have been adopted for treating refractory gold mixed copper concentrates. However，high-content of antimony seriously affect the lining life during matte smelting，and also have a negative impact on the subsequent recovery of valuable metals from anode slime. In consequence，it is of great significance to seek suitable technological strategies to pre-removed antimony from this high-Sb gold concentrates before being charged in bottom blowing melting furnace. In this work，Na2S+NaOH alkaline leaching was adopted to pre-remove Sb from high-antimony containing gold concentrates. Based on the chemical composition and mineralogical phases analysis，the process parameters of alkaline leaching were determined according to thermodynamic analysis and electrochemical potential （Eh）-pH diagram. Then，single-factor experiment was carried out to detect the effect of Na2S and NaOH concentration，temperature and liquid-solid ratio （L/S） on the leaching rate of Au and Sb，simultaneously，the inhibition mechanism of Mn to minimize co-leaching of gold caused by polysulfides and thiosulfates was also studied by means of electrochemistry analysis and X-ray photoelectron spectroscopy （XPS）. Furthermore，the gold contents in concentrates and leaching residues were analyzed by fire assay method，the chemical composition of others was analyzed by chemical titration and inductively coupled plasma mass spectrometry （ICP-MS）. Besides，the morphologies and phase structure were analyzed by scanning electron microscope-energy dispersive spectrometer （SEM-EDS），X-ray diffraction （XRD） and mineral phases analysis，especially the mineralogical phases of gold and antimony. The results showed that the major minerals in antimony bearing gold concentrates had been detected as stibnite （Sb2S3），arsenopyrite （FeAsS），pyrite （FeS2） and quartz （SiO2），etc. And antimony existed in a variety of forms，53% in the form of antimony sulfides and others were oxides. Moreover，the major antimony oxide was valentinite，and a few stibiconite and antimonate （Sb2O4），which was coexisted with pyrite，arsenopyrite and other flocculent substances. In addition，the gold was mainly wrapped by compounds such as sulfides and silicates，however，only a small amount of gold existed in the form of bare or semi-bare；among them，gold wrapped by antimony sulfide had the highest risk of loss in leaching. The appropriate addition of Na2S concentration could effectively improve the leaching rate of antimony，but too much S2− would lead to the addition of S2O32− and Sn2− in leaching solution，which accordingly increased the leaching rate of gold. Corresponding，the addition of NaOH could inhibit the hydrolysis of Na2S；instead，too high NaOH might remarkably accelerate the conversion rate of S2− to elemental sulfur，and restrain the dissolution and mass transfer of stibnite and antimony oxides. In view of the above，it was suitable to select Na2S 100 g·L−1+NaOH 100 g·L−1 for pre-removing antimony from refractory gold concentrates in leaching process. The rising temperature could effectively improve the reaction kinetic conditions，and the most important，it also reduced the content of dissolved oxygen in leaching solution，which might accordingly promote the leaching rate of antimony and suppress gold's dissolution. However，too high temperature dramatically intensified the decomposition of Na2S，in turn reducing the leaching rate of antimony. An appropriate L/S reduced the viscosity of solution and speeded up the leaching rate of antimony，but excessive L/S also increased the dissolution of oxygen，resulting in the associated leaching of gold. Taken together，the proper leaching temperature was optimized at 75 ℃ and L/S of 3∶1. Besides alkalinity，lowering solution potential could also avoid the oxidation of Na2S. Because Sb5+ was relatively stable in alkaline environment，which restricted the leaching of antimony to a certain extent，resulting in incomplete removal in leaching residue. In theory，Mn reacted with oxygen preferentially than S2−，which effective prevented the oxidative hydrolysis of Na2S to generate polysulfide and thiosulfate，and inhibited the dissolution of gold. The electrochemical and XPS analysis further revealed that Mn inhibitor had been oxidized to Mn2+，and gradually transformed into MnOOH and MnO（OH）2 in solutions，which reduced the redox potential，effectively prevented the oxidation from S2− to S2O32− and Sn2−，and alleviated associated leaching of gold. Under the optimal leaching conditions of Na2S 100 g·L−1+NaOH 100 g·L−1，L/S of 3∶1，Mn addition content of 5%，the antimony leaching rate reached 93.3%，leaching at 75 ℃ for 30 min，and compared with no inhibitor，the associated-leaching rate of gold was reduced by 65.33%，the content of antimony in leaching residues was lowered down to 1.75%，and 96.01% gold was enriched in leaching residues，which effectively achieved the desired targets for antimony pre-removal and gold enrichment in leaching residue.
KeyWords AITranslate
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Basic Information:
DOI：10.13373/j.cnki.cjrm.XY23030001
Chinese Library Classification Number:TF831
Citation Information:
With the gradual exhaustion of easy-to-treat gold mineral resources，gold production enterprises are pressured to utilize the refractory gold concentrate with high impurity contains arsenic and antimony as alternate. Since golds in these refractory ores are usually deposited with other metal sulphides and silicates，and mostly embedded in stibnites，pyrites and arsenopyrites，it is hard to achieve effective gold extraction by conventional wet process. Therefore，efficiently matte smelting capturing-Au technology have been adopted for treating refractory gold mixed copper concentrates. However，high-content of antimony seriously affect the lining life during matte smelting，and also have a negative impact on the subsequent recovery of valuable metals from anode slime. In consequence，it is of great significance to seek suitable technological strategies to pre-removed antimony from this high-Sb gold concentrates before being charged in bottom blowing melting furnace. In this work，Na2S+NaOH alkaline leaching was adopted to pre-remove Sb from high-antimony containing gold concentrates. Based on the chemical composition and mineralogical phases analysis，the process parameters of alkaline leaching were determined according to thermodynamic analysis and electrochemical potential （Eh）-pH diagram. Then，single-factor experiment was carried out to detect the effect of Na2S and NaOH concentration，temperature and liquid-solid ratio （L/S） on the leaching rate of Au and Sb，simultaneously，the inhibition mechanism of Mn to minimize co-leaching of gold caused by polysulfides and thiosulfates was also studied by means of electrochemistry analysis and X-ray photoelectron spectroscopy （XPS）. Furthermore，the gold contents in concentrates and leaching residues were analyzed by fire assay method，the chemical composition of others was analyzed by chemical titration and inductively coupled plasma mass spectrometry （ICP-MS）. Besides，the morphologies and phase structure were analyzed by scanning electron microscope-energy dispersive spectrometer （SEM-EDS），X-ray diffraction （XRD） and mineral phases analysis，especially the mineralogical phases of gold and antimony. The results showed that the major minerals in antimony bearing gold concentrates had been detected as stibnite （Sb2S3），arsenopyrite （FeAsS），pyrite （FeS2） and quartz （SiO2），etc. And antimony existed in a variety of forms，53% in the form of antimony sulfides and others were oxides. Moreover，the major antimony oxide was valentinite，and a few stibiconite and antimonate （Sb2O4），which was coexisted with pyrite，arsenopyrite and other flocculent substances. In addition，the gold was mainly wrapped by compounds such as sulfides and silicates，however，only a small amount of gold existed in the form of bare or semi-bare；among them，gold wrapped by antimony sulfide had the highest risk of loss in leaching. The appropriate addition of Na2S concentration could effectively improve the leaching rate of antimony，but too much S2− would lead to the addition of S2O32− and Sn2− in leaching solution，which accordingly increased the leaching rate of gold. Corresponding，the addition of NaOH could inhibit the hydrolysis of Na2S；instead，too high NaOH might remarkably accelerate the conversion rate of S2− to elemental sulfur，and restrain the dissolution and mass transfer of stibnite and antimony oxides. In view of the above，it was suitable to select Na2S 100 g·L−1+NaOH 100 g·L−1 for pre-removing antimony from refractory gold concentrates in leaching process. The rising temperature could effectively improve the reaction kinetic conditions，and the most important，it also reduced the content of dissolved oxygen in leaching solution，which might accordingly promote the leaching rate of antimony and suppress gold's dissolution. However，too high temperature dramatically intensified the decomposition of Na2S，in turn reducing the leaching rate of antimony. An appropriate L/S reduced the viscosity of solution and speeded up the leaching rate of antimony，but excessive L/S also increased the dissolution of oxygen，resulting in the associated leaching of gold. Taken together，the proper leaching temperature was optimized at 75 ℃ and L/S of 3∶1. Besides alkalinity，lowering solution potential could also avoid the oxidation of Na2S. Because Sb5+ was relatively stable in alkaline environment，which restricted the leaching of antimony to a certain extent，resulting in incomplete removal in leaching residue. In theory，Mn reacted with oxygen preferentially than S2−，which effective prevented the oxidative hydrolysis of Na2S to generate polysulfide and thiosulfate，and inhibited the dissolution of gold. The electrochemical and XPS analysis further revealed that Mn inhibitor had been oxidized to Mn2+，and gradually transformed into MnOOH and MnO（OH）2 in solutions，which reduced the redox potential，effectively prevented the oxidation from S2− to S2O32− and Sn2−，and alleviated associated leaching of gold. Under the optimal leaching conditions of Na2S 100 g·L−1+NaOH 100 g·L−1，L/S of 3∶1，Mn addition content of 5%，the antimony leaching rate reached 93.3%，leaching at 75 ℃ for 30 min，and compared with no inhibitor，the associated-leaching rate of gold was reduced by 65.33%，the content of antimony in leaching residues was lowered down to 1.75%，and 96.01% gold was enriched in leaching residues，which effectively achieved the desired targets for antimony pre-removal and gold enrichment in leaching residue.
quote
| GB/T 7714-2015 | [1] Feiyu Zhang, Yaru Cui, Xihong He, et al. Alkaline Sodium Sulfide Leaching of Antimony from High Antimony Gold Concentrates and Gold-Inhibition Mechanism[J]. Chinese Journal of Rare Metals, 2024, 48(12): 1732-1742. DOI:10.13373/j.cnki.cjrm.XY23030001. |
| MLA | [1] Feiyu Zhang, et al., "Alkaline Sodium Sulfide Leaching of Antimony from High Antimony Gold Concentrates and Gold-Inhibition Mechanism." Chinese Journal of Rare Metals, vol. 48, no. 12, 2024, pp. 1732-1742, https://doi.org/10.13373/j.cnki.cjrm.XY23030001. |
| APA | [1] Feiyu Zhang, Yaru Cui, Xihong He, Linbo Li, Chaofei Lv, Junfang Nan, Yufei Zhou, & Jinfeng Zhang. (2024). Alkaline Sodium Sulfide Leaching of Antimony from High Antimony Gold Concentrates and Gold-Inhibition Mechanism. Chinese Journal of Rare Metals, 48(12), 1732-1742. https://doi.org/10.13373/j.cnki.cjrm.XY23030001 |
| IEEE | [1] Feiyu Zhang, Yaru Cui, Xihong He, Linbo Li, Chaofei Lv, Junfang Nan, Yufei Zhou, and Jinfeng Zhang, "Alkaline Sodium Sulfide Leaching of Antimony from High Antimony Gold Concentrates and Gold-Inhibition Mechanism," Chinese Journal of Rare Metals, vol. 48, no. 12, pp. 1732-1742, 2024, doi: 10.13373/j.cnki.cjrm.XY23030001. keywords: {refractory gold concentrate containing high-antimony;alkaline sodium sulfide;manganese inhibitor;polysulphides and thiosulfates;associated leaching of gold} |