Microwave radiation was employed as a pretreating technology to oxidise a refractory gold ore. Heating characteristics showed that, in an identical microwave field, the bulk temperature of the sample increased with mi...Microwave radiation was employed as a pretreating technology to oxidise a refractory gold ore. Heating characteristics showed that, in an identical microwave field, the bulk temperature of the sample increased with microwave power, microwave radiation time and particle size. The rate of sulphur removal increased with microwave radiation time. Particle size also had a significant effect on the oxidation rate. Pyrite and marcasite could be oxidised into Fe 2O 3 with a high porous structure. When microwave radiation was carried out in a rotary bed, the oxidation was more uniformly developed, in comparison with in a fixed bed. Gold extraction by cyanidation could be remarkably improved after the ore was subjected to microwave radiation. The results showed that gold recovery could be improved from 37% to 69%~ 81.2 %.展开更多
The comprehensive recovery of small amounts of valuable minerals such as gold and base-metal sulfide minerals from a low-grade refractory ore was investigated. The following treatment strategy was applied to a sample ...The comprehensive recovery of small amounts of valuable minerals such as gold and base-metal sulfide minerals from a low-grade refractory ore was investigated. The following treatment strategy was applied to a sample of this ore: gold flotation-gold concen- trate leaching-lead and zinc flotation from the gold concentrate leaching residue. Closed-circuit trials of gold flotation yielded a gold concen- trate that assayed at 40.23 g·t-1 Au with a recovery of 86.25%. The gold concentrate leaching rate was 98.76%. Two variants of lead-zinc flotation from the residue--preferential flotation of lead and zinc and bulk flotation of lead and zinc--were tested using the middling processing method. Foam from the reflotation was returned to the lead rougher flotation or lead-zinc bulk flotation, whereas middlings from reflotation were discarded. Sulfur concentrate was a byproduct. The combined strategy of flotation, leaching, and flotation is recommended for the treatment of this kind of ore.展开更多
The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of ...The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs.In this work,the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions.Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite.The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments.The decomposition efficiency of thiourea decreased by 40%and the recovery efficiency of gold increased by 56%after the removal of sulfide by roasting.Under optimal conditions,the efficiency of the gold recovery system increased to 83.69%and only 57.92%of thiourea decomposition was observed.The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores,such as pyrite and soluble ferric oxide.展开更多
An combined technology of pressure pretreatment with oxygen on refractory gold ores is pointed out and discussed on this paper, according to the experiments included the test in 1 kg grade batch pressure pretreatment ...An combined technology of pressure pretreatment with oxygen on refractory gold ores is pointed out and discussed on this paper, according to the experiments included the test in 1 kg grade batch pressure pretreatment with oxygen of the concentrate from the refractory gold ores of Dongbeizhai in Sichuan province, which is called the most refractory gold ores in China. It is shown that gold recovery reach 91.73% in the combined process which is described as follows: The flotation of the sulphide gold ores is under controlled conditions, producing the concentrate for pressure pretreatment with oxygen in acidic medium and the middling for the pressure pretreatment with oxygen in alkaline medium. The thickening and washing process substitute the pressure filtration process of the pulp after pressure pretreatment. The thick slimes of the two kinds of pressure pretreatment were mixed and then enter the CIL process for simplifying the flowsheet. The possible superabundance of acid of pressure pretreatment with oxygen in acidic medium was neutralized by the tailings of flotation and the cost of neutralization will be lower. The combined technology of pressure pretreatment with oxygen has the same advantages as the normal technology of pressure pretreatment and both is helpful for environment protection.展开更多
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
BETTER knowledge of ore controls in Carlin-type deposits is important to efforts to understand depositionalmechanisms in these deposits. Fluid inclusion and phase equilibria show that these deposits formed undertemper...BETTER knowledge of ore controls in Carlin-type deposits is important to efforts to understand depositionalmechanisms in these deposits. Fluid inclusion and phase equilibria show that these deposits formed undertemperatures typical of epithermal conditions, although both salinities and pressures may have been higher. Unlike adualria-sericite gold vein deposits that are thought to form by boiling, there is little agreementabout the process that caused gold deposition in Carlin-type deposits.展开更多
A solution containing nanometer-sized pure gold particles was prepared with the hydrolysisreduction method. As observed under the electron microscope, the gold particles were as large as 2—20 nm in size. Different ki...A solution containing nanometer-sized pure gold particles was prepared with the hydrolysisreduction method. As observed under the electron microscope, the gold particles were as large as 2—20 nm in size. Different kinds of mineral and rock were put into the solution and the experimental result showed that the nanometer-sized gold particles are obviously adsorbed on sulfide minerals, native copper and carbonaceous rocks. This experimental result is consistent with the actual geological observation. On this basis a better explanation is presented of the genesis of the Carlin-type gold deposits.展开更多
1 Geology CARLJN-TYPE gold deposits (CTDs) consist of extremely fine-grained gold that is generally submicron topossibly atomic in size. Most of the gold is hosted by hydrothermal arsenian pyrite and quartz, with less...1 Geology CARLJN-TYPE gold deposits (CTDs) consist of extremely fine-grained gold that is generally submicron topossibly atomic in size. Most of the gold is hosted by hydrothermal arsenian pyrite and quartz, with lesseramounts present in carbonaceous matter and fine-grained phyllosilicates. In the Great Basin, the hostrocks consist primarily of Paleozoic sedimentary rocks, although few deposits are located primarily inyounger sedimentary rocks and minor mineralization also occurs in igneous rocks in some deposits.The most common host rock types are silty carbonates to calcareous siltstones and calcareous shales. Manydeposits are spatially associated with matured hydrocarbon accumulations (kerogen), but it is unclearwhether these hydrocarbons played an active or passive role in ore depositional process. There is significant structural control on the localization of ore zones in CTDs, consisting of bothfolds and faults. The general geometry of the ore zones comprises a feeder zone, commonly controlled展开更多
文摘Microwave radiation was employed as a pretreating technology to oxidise a refractory gold ore. Heating characteristics showed that, in an identical microwave field, the bulk temperature of the sample increased with microwave power, microwave radiation time and particle size. The rate of sulphur removal increased with microwave radiation time. Particle size also had a significant effect on the oxidation rate. Pyrite and marcasite could be oxidised into Fe 2O 3 with a high porous structure. When microwave radiation was carried out in a rotary bed, the oxidation was more uniformly developed, in comparison with in a fixed bed. Gold extraction by cyanidation could be remarkably improved after the ore was subjected to microwave radiation. The results showed that gold recovery could be improved from 37% to 69%~ 81.2 %.
基金financially supported by the National Natural Science Foundation of China (No. 51504031)
文摘The comprehensive recovery of small amounts of valuable minerals such as gold and base-metal sulfide minerals from a low-grade refractory ore was investigated. The following treatment strategy was applied to a sample of this ore: gold flotation-gold concen- trate leaching-lead and zinc flotation from the gold concentrate leaching residue. Closed-circuit trials of gold flotation yielded a gold concen- trate that assayed at 40.23 g·t-1 Au with a recovery of 86.25%. The gold concentrate leaching rate was 98.76%. Two variants of lead-zinc flotation from the residue--preferential flotation of lead and zinc and bulk flotation of lead and zinc--were tested using the middling processing method. Foam from the reflotation was returned to the lead rougher flotation or lead-zinc bulk flotation, whereas middlings from reflotation were discarded. Sulfur concentrate was a byproduct. The combined strategy of flotation, leaching, and flotation is recommended for the treatment of this kind of ore.
基金This work was financially supported by the National Natural Science Foundation of China(No.51922108)the Hunan Natural Science Foundation(No.2019JJ20031)the Hunan Key Research and Development Program(No.2019SK2061).
文摘The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs.In this work,the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions.Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite.The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments.The decomposition efficiency of thiourea decreased by 40%and the recovery efficiency of gold increased by 56%after the removal of sulfide by roasting.Under optimal conditions,the efficiency of the gold recovery system increased to 83.69%and only 57.92%of thiourea decomposition was observed.The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores,such as pyrite and soluble ferric oxide.
文摘An combined technology of pressure pretreatment with oxygen on refractory gold ores is pointed out and discussed on this paper, according to the experiments included the test in 1 kg grade batch pressure pretreatment with oxygen of the concentrate from the refractory gold ores of Dongbeizhai in Sichuan province, which is called the most refractory gold ores in China. It is shown that gold recovery reach 91.73% in the combined process which is described as follows: The flotation of the sulphide gold ores is under controlled conditions, producing the concentrate for pressure pretreatment with oxygen in acidic medium and the middling for the pressure pretreatment with oxygen in alkaline medium. The thickening and washing process substitute the pressure filtration process of the pulp after pressure pretreatment. The thick slimes of the two kinds of pressure pretreatment were mixed and then enter the CIL process for simplifying the flowsheet. The possible superabundance of acid of pressure pretreatment with oxygen in acidic medium was neutralized by the tailings of flotation and the cost of neutralization will be lower. The combined technology of pressure pretreatment with oxygen has the same advantages as the normal technology of pressure pretreatment and both is helpful for environment protection.
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BETTER knowledge of ore controls in Carlin-type deposits is important to efforts to understand depositionalmechanisms in these deposits. Fluid inclusion and phase equilibria show that these deposits formed undertemperatures typical of epithermal conditions, although both salinities and pressures may have been higher. Unlike adualria-sericite gold vein deposits that are thought to form by boiling, there is little agreementabout the process that caused gold deposition in Carlin-type deposits.
文摘A solution containing nanometer-sized pure gold particles was prepared with the hydrolysisreduction method. As observed under the electron microscope, the gold particles were as large as 2—20 nm in size. Different kinds of mineral and rock were put into the solution and the experimental result showed that the nanometer-sized gold particles are obviously adsorbed on sulfide minerals, native copper and carbonaceous rocks. This experimental result is consistent with the actual geological observation. On this basis a better explanation is presented of the genesis of the Carlin-type gold deposits.
文摘1 Geology CARLJN-TYPE gold deposits (CTDs) consist of extremely fine-grained gold that is generally submicron topossibly atomic in size. Most of the gold is hosted by hydrothermal arsenian pyrite and quartz, with lesseramounts present in carbonaceous matter and fine-grained phyllosilicates. In the Great Basin, the hostrocks consist primarily of Paleozoic sedimentary rocks, although few deposits are located primarily inyounger sedimentary rocks and minor mineralization also occurs in igneous rocks in some deposits.The most common host rock types are silty carbonates to calcareous siltstones and calcareous shales. Manydeposits are spatially associated with matured hydrocarbon accumulations (kerogen), but it is unclearwhether these hydrocarbons played an active or passive role in ore depositional process. There is significant structural control on the localization of ore zones in CTDs, consisting of bothfolds and faults. The general geometry of the ore zones comprises a feeder zone, commonly controlled