Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanid...Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanide complex is robbed by adsorption of carbonaceous matter, which is similar to activated carbon in cyanide leaching of gold. The pretreatment methods of carbonaceous gold ores were introduced, including high temperature roasting, bio-oxidation, chemical oxidation, competitive adsorption, barrier inhibition and microwave roasting. Recently, bio-oxidation was developed rapidly due to its advantages such as mild conditions, simple processes, low energy consumption and friendly environment. The known microorganisms related with bio-oxidation pretreatment mainly are chemolithotroph bacteria such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The researches on decomposing and passivating carbonaceous matter were commenced by Phanerochaete chrysosporium, Pseudomonadaceae and Streptomyces setonii. Finally, the main problems were analyzed and the application prospect of this technique was looked forward.展开更多
Pyrolusite was added in the bioleaching process to enhance the bio-oxidation process. Bioleaching tests at different dosages of pyrolusite ore, pH and inoculation amounts of Acidithiobacillus ferrooxidans were studied...Pyrolusite was added in the bioleaching process to enhance the bio-oxidation process. Bioleaching tests at different dosages of pyrolusite ore, pH and inoculation amounts of Acidithiobacillus ferrooxidans were studied. The results showed that the time of the bio-oxidation process was decreased obviously and the arsenic leaching rate reached 94.4% after the bioleaching. The bio-oxidation of arsenopyrite and the effective extraction of manganese from pyrolusite were achieved by the bioleaching process. After bioleaching, the leaching rate of gold from the reaction residues reached 95.8% by cyanide leaching. In the bio-oxidation process, pyrolusite increased the redox potential of the solution to accelerate the bioleaching rate. The experiment showed that there were two reaction modes in the bioleaching process.展开更多
Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to colle...Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to collect more efficient strain for bioleaching of gold ore. Physiological and biochemical characteristics indicate that strain YXW is a strict chemoautotrophic microorganism, and the optimal condition for its growth is temperature of 40 °C and pH 1.5. After mutation by ultrasonic, UV and microwave, the density of bacterial cells reached 9×109, 8.4×109 and 4.3×108 mL-1, increased by 291%, 265%and 87%, respectively, compared with the original culture. The bacterial total protein activity was improved by microwave and UV mutations, but was reduced by ultrasonic. Mutations had effects on bioleaching of gold ore in sequence of microwave〉UV〉ultrasonic. During gold ore bioleaching, the bacterial mutant after mutation by microwave had the best effect on the extraction rates of arsenic and iron, which were 19.6%and 17.7%higher than that of the original strain after bioleaching for 10 d, respectively. The results suggested that the effects of mutation on bioleaching of gold ore may not be mainly due to increase of bacterial cells density, but may be mainly attributed to the improvement of bacterial total protein activity.展开更多
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
A novel process based on chlorination roasting was proposed to simultaneously recover gold and zinc from refractory carbonaceous gold ore by using NaCl as chlorination agent.The effects of roasting temperature,roastin...A novel process based on chlorination roasting was proposed to simultaneously recover gold and zinc from refractory carbonaceous gold ore by using NaCl as chlorination agent.The effects of roasting temperature,roasting time and NaCl content on the volatilization rates of gold and zinc were investigated.The reaction mechanism and the phase transition process were also analyzed by means of SEM,EDS and XRD.The results demonstrated that under the optimal conditions of NaCl content of 10%,roasting temperature of 800℃,roasting time of 4 h and gas flow rate of 1 L/min,the rates of gold and zinc were 92%and 92.56%,respectively.During low-temperature chlorination roasting stage,a certain content of sulfur was beneficial to the chlorination reactions of gold and zinc;and during high-temperature chlorination roasting stage,the crystal structure of vanadium-bearing mica was destroyed,and the vanadium-containing oxides were beneficial to the chlorinating volatilization of gold and zinc.Eventually,the chlorinated volatiles of gold and zinc could be recovered by alkaline solution.展开更多
The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching...The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic.The results show that the concentration of As 3+ is larger than that of As 5+ in the lag phase.The concentration of As 3+ decreases in the log phase,and is lower than that of As5 +.HQ-0211 typed bacteria express better resistance for As 3+and As 5+and remain growing when the concentrations of As3 +and As 5+are above 6.0 g/L and 12.0 g/L,respectively.It is found that Fe 3+cannot oxidize As3 +singly as strong oxidant in the leaching system,but can cooperate with pyrite or chalcopyrite to do that.The oxidation of As 3+ is prompted with addition of H2O2.The bacterial activity is improved in favor of bacterial leaching efficiency.NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.展开更多
To design heap biooxidation process,it is necessary to understand its internal rules.The heap biooxidation of gold ore from Anhui province was researched in this study.The results showed that the main microorganisms i...To design heap biooxidation process,it is necessary to understand its internal rules.The heap biooxidation of gold ore from Anhui province was researched in this study.The results showed that the main microorganisms in the heap were A.ferrooxidans,F.acidiphilum and L.ferrodiazotrophum.Under their combined action,gold leaching extent rose from 35.62%to 78.08%in 80 d.Boltzmann model matches the actual oxidation effect better and the model equations were obtained.The model predicted that the oxidation extents of arsenic and sulfur are 58.577%and 42.122%after one year,and the gold leaching extent was 80.40%.The arsenic and sulfur oxidation extents,and gold leaching extent were all linearly correlated.It is more reliable to predict gold leaching extent by sulfur oxidation extent.These results provided good guidance for practical application in the actual production.展开更多
The resources of refractory gold ores are abundant, and their effective treatment can bring good economic benefits. This paper investigated the kinetics of leaching gold from refractory gold ores by ultrasonic-assiste...The resources of refractory gold ores are abundant, and their effective treatment can bring good economic benefits. This paper investigated the kinetics of leaching gold from refractory gold ores by ultrasonic-assisted electro-chlorination. The effects of ultrasound time ratio, initial hydrochloric acid concentration and leaching temperature on the kinetic parameters were discussed. It is found that the leaching ratio goes up with all the factors increasing. The reaction kinetics is controlled by diffusion. When ultrasound improves the diffusion by reducing the diffusion resistance, the activation energy increases to 37.1 kJ/mol.展开更多
Carbonate decomposition of carbonic refractory gold ore and the following pressure oxidation were studied.In the carbonate decomposition procedure,the effects of liquid-to-solid ratio and reaction time on decompositio...Carbonate decomposition of carbonic refractory gold ore and the following pressure oxidation were studied.In the carbonate decomposition procedure,the effects of liquid-to-solid ratio and reaction time on decomposition ratio of carbonate were investigated.The experimental result shows that the decomposition ratio of carbonate is 98.24%under the conditions of liquid-to-solid ratio of 5:1,Fe^(3+)concentration of 20 g/L,sulfuric acid concentration of 20 g/L,reaction temperature of 80 ℃ and reaction time of 2 h.Then,the slurry obtained from carbonate decomposition was put into the titanium autoclave for pressure oxidation leaching.Effects of liquid-to-solid ratio,temperature,time and oxygen partial pressure on sulfur oxidation ratio were studied during pressure oxidation.With the prolonged time,pyrite and arsenopyrite are oxidized to ferric subsulfate,hydrated ferric sulfate and jarosite,resulting in the increasing residue ratio.The residue ratio and the sulfur content in the residue can be decreased by ferric subsulfate dissolution.The oxidation ratio of the sulfur is 99.35% under the conditions of oxidation time of 4 h,temperature of 210 ℃,oxygen partial pressure of 0.8 MPa and stirring speed of 600 r/min.展开更多
In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb a...In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.展开更多
The present work investigated microbial leaching of zinc from ore using Acidithiobacillus ferrooxidans （ATCC 14859）. The ore samples, consisted of 13wt% zinc, were obtained from a gold mine in north-eastern Thailand...The present work investigated microbial leaching of zinc from ore using Acidithiobacillus ferrooxidans （ATCC 14859）. The ore samples, consisted of 13wt% zinc, were obtained from a gold mine in north-eastern Thailand. A shake flask study was performed on the ore samples using a rotary shaker under the following fixed conditions （250 r·min^-1, 30℃ for 16 d）. The influence of various conditions, namely medium type （with and without iron）, particle ore size （〈20, 20-40, 40-60, 60-100, and 〉100 mesh）, ore density （20 kg·m^-3, 50 kg·m^-3, and 100 kg·m^-3）, and pH of the medium （2, 2.5, 2.8, and 3）, were investigated. The microbial leaching was assessed by determining the concentration of zinc in the medium and compared with the initial sample concentration. The results show that Acidithiobacillus ferrooxidans can successfully leach zinc by as much as 6 times compared with the control experiment （without Acidithiobacillus ferrooxidans ferrooxidans）. The maximum efficiency （92.3%） for microbial leaching is obtained in iron-containing medium, 20-40 mesh ore sizes, 20 kg·m^-3 ore density at pH 2.8, and the zinc content is found in the medium at about 120 mg·m^-1.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
Gold ore processing is often ineffective in obtaining gold metal. Various methods have been successfully developed on an industrial scale, but small-scale gold mines are often problematic. The problem of inefficiency ...Gold ore processing is often ineffective in obtaining gold metal. Various methods have been successfully developed on an industrial scale, but small-scale gold mines are often problematic. The problem of inefficiency of processing is caused by gold ore characterization and evaluation of gold ore preparation process is not implemented. In this study, the conditions of gold ore deposits have a thin thickness （vein）. These gold ore deposits have an economic value if they are developed by traditional gold mining. The objective of the research is to identify and characterize gold ore as well as to analyze the optimum condition to obtain the perfect gold mineral liberation degree. Research methods include characterization of gold ore geology, sampling for test preparation using rod mill （amalgamation）, gold mineral liberation using time variables and number of rods. After the grinding process, grain size analysis is performed with various mesh sizes, and the analysis of each fraction uses a polarization microscope. The results show that gold ore minerals are associated with pyrite, chalcopyrite, galena and gangue minerals. Gold minerals are fully liberated at a certain size. The results of this research are very useful for the gold ore grinding process to obtain an efficient gold processing.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
The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the nega...The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly ThiobaciUus ferrooxidan （named T.fl ）, as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5, and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day＇s bio-oxidization, among the samples sizing from 0 to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.展开更多
Five gold deposits (mineralization) were found in the study area by means of geologi</span><span style="font-family:Verdana;">cal mapping, soil geochemical survey and trough exploration engineeri...Five gold deposits (mineralization) were found in the study area by means of geologi</span><span style="font-family:Verdana;">cal mapping, soil geochemical survey and trough exploration engineering. The</span><span style="font-family:Verdana;"> ore-bearing lithology is mainly metam</span></span><span style="font-family:Verdana;">orphic feldspar sandstone of </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">Upper Carboniferous Benbatu Formation, and the gold (mineralization) body is controlled by both structural factors </span><span style="font-family:Verdana;">and stratigraphic factors of </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">Upper Carboniferous Benbatu Formation. The genetic</span><span style="font-family:""><span style="font-family:Verdana;"> type is preliminary concluded to be volcanic hyd</span><span style="color:black;font-family:Verdana;">rothermal type, and the metallogenic age is late Variscan. In this paper, by studying the geological characteristics and metallogenic geological conditions of the gold orebody in the area, a regional prospecting model has been established, which is of great significance to better guide the prospecting work of similar gold deposits in the area and the region.展开更多
The response of Imogbara (Nigeria) gold ore to shaking tabling gravity separation methods was investigated in this research work. Gold concentration in run-off mines is usually as low as 0.005 ppm and must be upgraded...The response of Imogbara (Nigeria) gold ore to shaking tabling gravity separation methods was investigated in this research work. Gold concentration in run-off mines is usually as low as 0.005 ppm and must be upgraded in order to reduce the recovery process extraction costs. Gravity separation method (the focus of this work) is one of the readily affordable beneficiation methods. Shaking table is a developed separation equipment of gravity method that has been adopted to increase concentrate based on difference of specific gravity. The output result of the concentration process using shaking table is basically influenced by a number of variables, such as rotational shaking speed, particle size and deck slope. In this research, the range of rotational speed shaking was between 100 rpm and 200 rpm, the particle size was between (−300 μm > X −75 μm) and deck slope was between 10°and 30°. EDXRF was used to measure gold concentration in the concentrate as well as the tailings. The result shows that the optimum condition is obtained at a shaking speed of 100 rpm, with a slope of 10°and particle size less than 75 μm.展开更多
Altai polymetallic mineralization belt is famous copper-polymetallic mineralization belt in the world. There are a lot of gold deposits in the Altai ore belt in Xinjiang, China. These gold deposits belong to two genet...Altai polymetallic mineralization belt is famous copper-polymetallic mineralization belt in the world. There are a lot of gold deposits in the Altai ore belt in Xinjiang, China. These gold deposits belong to two genetic types: volcanogene late-stage hydrothermal type and fractured altered rock type. The authors discuss mainly the geological and mineralized features of fractured altered rock type of gold deposits in Altai gold ore belt. Base on this study, the metallogenic law is summarized and the deep metallogenic prognosis has been done in Duolanasayi and Tuokuzibayi gold deposits, and some mineralized anomalys have been discovered.展开更多
To overcome the limitations of geography,climate,and ore characteristics on the ore beneficiation process,biooxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out,as well...To overcome the limitations of geography,climate,and ore characteristics on the ore beneficiation process,biooxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out,as well as process fitting analysis.The gold particles are encapsulated by pyrite and arsenopyrite.After 60 days of biooxidation,the oxidation rates of arsenic,sulfur,and gold were 39%~69%,24%~41%,and 49%~83%,respectively.The inoculated Acidithiobacillus ferrooxidans,Ferroplasma acidiphilum,and Leptospirillum ferrodiazotrophum could all mediate the initial pyrite/arsenopyrite oxidation and the Fe^(2+)oxidation reaction,but only the former could mediate the subsequent sulfur compound oxidation.When compared to daily bacterial circulation and bacterial replacement every ten days,aeration improved the gold leaching rate by 14%~22%.The Boltzmann model could fit both the arsenic and sulfur bio-oxidation,with model fit variances greater than 0.98.Based on the experimental and fitting results,the bio-oxidation cycle was determined to be 60 days,and the bio-oxidation mechanisms are summarized.This study has significant practical implications for the rational utilization of gold resources and provides theoretical and practical guidance for similar gold ores.展开更多
基金Projects(51174062,51104036)supported by the National Natural Science Foundation of ChinaProject(2012BAE06B05)supported by the National Science and Technology Support Program of China during the 12th Five-Year Plan Period+1 种基金Projects(2012AA061502,2012AA061501)supported by the National High-Tech Research and Development Program of ChinaProjects(N120602006,N110302002,N110602005)supported by Fundamental Research Funds for the Central Universities of China
文摘Carbonaceous gold mines are important refractory gold ores. The previous results demonstrate that the carbonaceous matter is mainly composed of elemental carbon, organic acid and hydrocarbons. The dissolved aurocyanide complex is robbed by adsorption of carbonaceous matter, which is similar to activated carbon in cyanide leaching of gold. The pretreatment methods of carbonaceous gold ores were introduced, including high temperature roasting, bio-oxidation, chemical oxidation, competitive adsorption, barrier inhibition and microwave roasting. Recently, bio-oxidation was developed rapidly due to its advantages such as mild conditions, simple processes, low energy consumption and friendly environment. The known microorganisms related with bio-oxidation pretreatment mainly are chemolithotroph bacteria such as Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. The researches on decomposing and passivating carbonaceous matter were commenced by Phanerochaete chrysosporium, Pseudomonadaceae and Streptomyces setonii. Finally, the main problems were analyzed and the application prospect of this technique was looked forward.
基金Project(2015ZX07205-003)supported by the National Water Pollution Control and Treatment Science,ChinaProject(DY125-15-T-08)supported by China Ocean Mineral Resource R&D Association+1 种基金Project(2012BAB07B05)supported by the National Key Technology R&D Program of ChinaProject(2012AA062401)supported by the National High-tech Research and Development Program of China
文摘Pyrolusite was added in the bioleaching process to enhance the bio-oxidation process. Bioleaching tests at different dosages of pyrolusite ore, pH and inoculation amounts of Acidithiobacillus ferrooxidans were studied. The results showed that the time of the bio-oxidation process was decreased obviously and the arsenic leaching rate reached 94.4% after the bioleaching. The bio-oxidation of arsenopyrite and the effective extraction of manganese from pyrolusite were achieved by the bioleaching process. After bioleaching, the leaching rate of gold from the reaction residues reached 95.8% by cyanide leaching. In the bio-oxidation process, pyrolusite increased the redox potential of the solution to accelerate the bioleaching rate. The experiment showed that there were two reaction modes in the bioleaching process.
基金Project(41073060)supported by the National Natural Science Foundation of ChinaProject(12ZR1440400)supported by the Shanghai Natural Science Foundation of Youth,China+1 种基金Project(B604)supported by the Shanghai Leading Academic Discipline,ChinaProject supported by the State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry,China
文摘Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to collect more efficient strain for bioleaching of gold ore. Physiological and biochemical characteristics indicate that strain YXW is a strict chemoautotrophic microorganism, and the optimal condition for its growth is temperature of 40 °C and pH 1.5. After mutation by ultrasonic, UV and microwave, the density of bacterial cells reached 9×109, 8.4×109 and 4.3×108 mL-1, increased by 291%, 265%and 87%, respectively, compared with the original culture. The bacterial total protein activity was improved by microwave and UV mutations, but was reduced by ultrasonic. Mutations had effects on bioleaching of gold ore in sequence of microwave〉UV〉ultrasonic. During gold ore bioleaching, the bacterial mutant after mutation by microwave had the best effect on the extraction rates of arsenic and iron, which were 19.6%and 17.7%higher than that of the original strain after bioleaching for 10 d, respectively. The results suggested that the effects of mutation on bioleaching of gold ore may not be mainly due to increase of bacterial cells density, but may be mainly attributed to the improvement of bacterial total protein activity.
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 %.
文摘A novel process based on chlorination roasting was proposed to simultaneously recover gold and zinc from refractory carbonaceous gold ore by using NaCl as chlorination agent.The effects of roasting temperature,roasting time and NaCl content on the volatilization rates of gold and zinc were investigated.The reaction mechanism and the phase transition process were also analyzed by means of SEM,EDS and XRD.The results demonstrated that under the optimal conditions of NaCl content of 10%,roasting temperature of 800℃,roasting time of 4 h and gas flow rate of 1 L/min,the rates of gold and zinc were 92%and 92.56%,respectively.During low-temperature chlorination roasting stage,a certain content of sulfur was beneficial to the chlorination reactions of gold and zinc;and during high-temperature chlorination roasting stage,the crystal structure of vanadium-bearing mica was destroyed,and the vanadium-containing oxides were beneficial to the chlorinating volatilization of gold and zinc.Eventually,the chlorinated volatiles of gold and zinc could be recovered by alkaline solution.
基金Projects(50674029, 50874030) supported by the National Natural Science Foundation of ChinaProject(2006AA06Z127) supported by the National High-tech Research and Development Program of ChinaProject(20060145015) supported by Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘The concentration and variational trend of As3 +and As 5+,the bacterial resistance for the As 3+and As 5+and converting conditions from As3 +to As 5+were analyzed.The additive was used to prompt the bacterial leaching efficiency by changing valence state of arsenic.The results show that the concentration of As 3+ is larger than that of As 5+ in the lag phase.The concentration of As 3+ decreases in the log phase,and is lower than that of As5 +.HQ-0211 typed bacteria express better resistance for As 3+and As 5+and remain growing when the concentrations of As3 +and As 5+are above 6.0 g/L and 12.0 g/L,respectively.It is found that Fe 3+cannot oxidize As3 +singly as strong oxidant in the leaching system,but can cooperate with pyrite or chalcopyrite to do that.The oxidation of As 3+ is prompted with addition of H2O2.The bacterial activity is improved in favor of bacterial leaching efficiency.NaClO restrains the bacterial growth to depress leaching efficiency because of the chloric compounds affecting bacterial activity.
基金Project(U1608254)supported by the Special Fund for the National Natural Science Foundation of ChinaProjects(ZJKY2017(B)KFJJ01,ZJKY2017(B)KFJJ02)supported by the Zijin Mining Group Co.,Ltd,China。
文摘To design heap biooxidation process,it is necessary to understand its internal rules.The heap biooxidation of gold ore from Anhui province was researched in this study.The results showed that the main microorganisms in the heap were A.ferrooxidans,F.acidiphilum and L.ferrodiazotrophum.Under their combined action,gold leaching extent rose from 35.62%to 78.08%in 80 d.Boltzmann model matches the actual oxidation effect better and the model equations were obtained.The model predicted that the oxidation extents of arsenic and sulfur are 58.577%and 42.122%after one year,and the gold leaching extent was 80.40%.The arsenic and sulfur oxidation extents,and gold leaching extent were all linearly correlated.It is more reliable to predict gold leaching extent by sulfur oxidation extent.These results provided good guidance for practical application in the actual production.
基金supported by the Key Subject of Shanghai Municipality (No.S30109)Shanghai Science and Technology Commission (No.10dz1205302)
文摘The resources of refractory gold ores are abundant, and their effective treatment can bring good economic benefits. This paper investigated the kinetics of leaching gold from refractory gold ores by ultrasonic-assisted electro-chlorination. The effects of ultrasound time ratio, initial hydrochloric acid concentration and leaching temperature on the kinetic parameters were discussed. It is found that the leaching ratio goes up with all the factors increasing. The reaction kinetics is controlled by diffusion. When ultrasound improves the diffusion by reducing the diffusion resistance, the activation energy increases to 37.1 kJ/mol.
基金Project(51404296)supported by the Young Scientists Fund of National Natural Science Foundation of ChinaProject(134414)supported by the Postdoctoral Funded Program of Central South University,China
文摘Carbonate decomposition of carbonic refractory gold ore and the following pressure oxidation were studied.In the carbonate decomposition procedure,the effects of liquid-to-solid ratio and reaction time on decomposition ratio of carbonate were investigated.The experimental result shows that the decomposition ratio of carbonate is 98.24%under the conditions of liquid-to-solid ratio of 5:1,Fe^(3+)concentration of 20 g/L,sulfuric acid concentration of 20 g/L,reaction temperature of 80 ℃ and reaction time of 2 h.Then,the slurry obtained from carbonate decomposition was put into the titanium autoclave for pressure oxidation leaching.Effects of liquid-to-solid ratio,temperature,time and oxygen partial pressure on sulfur oxidation ratio were studied during pressure oxidation.With the prolonged time,pyrite and arsenopyrite are oxidized to ferric subsulfate,hydrated ferric sulfate and jarosite,resulting in the increasing residue ratio.The residue ratio and the sulfur content in the residue can be decreased by ferric subsulfate dissolution.The oxidation ratio of the sulfur is 99.35% under the conditions of oxidation time of 4 h,temperature of 210 ℃,oxygen partial pressure of 0.8 MPa and stirring speed of 600 r/min.
文摘In this work, different flotation–preoxidation–cyanidation methods are considered for treating a lowgrade refractory gold ore. On the one hand, the results of selective flotation show that 22% and 31.1%of total Sb and As, respectively, remained in the final tailings and only about 28% of the total Au remained for further cyanidation processes. On the other hand, in bulk method of flotation the maximum Au recovery of 90.6% achieved after 60 min of flotation at the grind size with K80 of 146 micron. In addition, the bulk flotation method resulted in the concentrate with low concentrations of Sb and As elements. To improve the recovery of low-grade refractory gold ores, flotation should be followed by roasting, biological, or pressure oxidation processes so that the gold could be liberated prior to cyanidation processes. It is also found that the pressure oxidation pre-treatment of the concentrates prior to cyanidation may yield high gold recoveries of over than 83%. In these processes, recoveries are controlled by the temperature and the oxygen partial pressure in the solvent. However, by utilizing the bio-oxidation technique, the oxidation of sulfur to sulfate cannot be completed and, consequently, the gold recovery may be limited to only 72.2%.
文摘The present work investigated microbial leaching of zinc from ore using Acidithiobacillus ferrooxidans （ATCC 14859）. The ore samples, consisted of 13wt% zinc, were obtained from a gold mine in north-eastern Thailand. A shake flask study was performed on the ore samples using a rotary shaker under the following fixed conditions （250 r·min^-1, 30℃ for 16 d）. The influence of various conditions, namely medium type （with and without iron）, particle ore size （〈20, 20-40, 40-60, 60-100, and 〉100 mesh）, ore density （20 kg·m^-3, 50 kg·m^-3, and 100 kg·m^-3）, and pH of the medium （2, 2.5, 2.8, and 3）, were investigated. The microbial leaching was assessed by determining the concentration of zinc in the medium and compared with the initial sample concentration. The results show that Acidithiobacillus ferrooxidans can successfully leach zinc by as much as 6 times compared with the control experiment （without Acidithiobacillus ferrooxidans ferrooxidans）. The maximum efficiency （92.3%） for microbial leaching is obtained in iron-containing medium, 20-40 mesh ore sizes, 20 kg·m^-3 ore density at pH 2.8, and the zinc content is found in the medium at about 120 mg·m^-1.
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Gold ore processing is often ineffective in obtaining gold metal. Various methods have been successfully developed on an industrial scale, but small-scale gold mines are often problematic. The problem of inefficiency of processing is caused by gold ore characterization and evaluation of gold ore preparation process is not implemented. In this study, the conditions of gold ore deposits have a thin thickness （vein）. These gold ore deposits have an economic value if they are developed by traditional gold mining. The objective of the research is to identify and characterize gold ore as well as to analyze the optimum condition to obtain the perfect gold mineral liberation degree. Research methods include characterization of gold ore geology, sampling for test preparation using rod mill （amalgamation）, gold mineral liberation using time variables and number of rods. After the grinding process, grain size analysis is performed with various mesh sizes, and the analysis of each fraction uses a polarization microscope. The results show that gold ore minerals are associated with pyrite, chalcopyrite, galena and gangue minerals. Gold minerals are fully liberated at a certain size. The results of this research are very useful for the gold ore grinding process to obtain an efficient gold processing.
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The refractory gold ores associated with rich copper and trapped in pyrite and quartz were studied. With conventional technique （all-sliming cyanidation）, the gold recovery rate is only 51.78%. To eliminate the negative effects of copper and pyrite on cyanidation and increase the gold recovery rate, the investigation on bio-heap leaching pretreatment was made, by which Cu would be dissolved and gold would be liberated from pyrite. The experiment adopted mixed bacteria, mainly ThiobaciUus ferrooxidan （named T.fl ）, as the bacterial catalyst for bio-preconditioning and was carried out in a PVC column with a diameter of 20 cm and a height of 1.3 m loaded with gold ores. The temperature was controlled between 28 and 30℃, the pH value was kept between 2.0-2.5, and the flux of sprinkling bacterial liquid was maintained 0.80 L/h. After 45-day＇s bio-oxidization, among the samples sizing from 0 to 5 mm, the oxidation rates of Cu, Fe and S were respectively 44.62%, 28.16% and 25.46%, and the gold recovery rate by cyaniding increased to 80.35%. The bio-heap leaching pretreatment can therefore effectively dissolve Cu and liberate gold from pyrite and lead to the increase of gold extraction.
文摘Five gold deposits (mineralization) were found in the study area by means of geologi</span><span style="font-family:Verdana;">cal mapping, soil geochemical survey and trough exploration engineering. The</span><span style="font-family:Verdana;"> ore-bearing lithology is mainly metam</span></span><span style="font-family:Verdana;">orphic feldspar sandstone of </span><span style="font-family:Verdana;">the </span><span style="font-family:""><span style="font-family:Verdana;">Upper Carboniferous Benbatu Formation, and the gold (mineralization) body is controlled by both structural factors </span><span style="font-family:Verdana;">and stratigraphic factors of </span></span><span style="font-family:Verdana;">the </span><span style="font-family:Verdana;">Upper Carboniferous Benbatu Formation. The genetic</span><span style="font-family:""><span style="font-family:Verdana;"> type is preliminary concluded to be volcanic hyd</span><span style="color:black;font-family:Verdana;">rothermal type, and the metallogenic age is late Variscan. In this paper, by studying the geological characteristics and metallogenic geological conditions of the gold orebody in the area, a regional prospecting model has been established, which is of great significance to better guide the prospecting work of similar gold deposits in the area and the region.
文摘The response of Imogbara (Nigeria) gold ore to shaking tabling gravity separation methods was investigated in this research work. Gold concentration in run-off mines is usually as low as 0.005 ppm and must be upgraded in order to reduce the recovery process extraction costs. Gravity separation method (the focus of this work) is one of the readily affordable beneficiation methods. Shaking table is a developed separation equipment of gravity method that has been adopted to increase concentrate based on difference of specific gravity. The output result of the concentration process using shaking table is basically influenced by a number of variables, such as rotational shaking speed, particle size and deck slope. In this research, the range of rotational speed shaking was between 100 rpm and 200 rpm, the particle size was between (−300 μm > X −75 μm) and deck slope was between 10°and 30°. EDXRF was used to measure gold concentration in the concentrate as well as the tailings. The result shows that the optimum condition is obtained at a shaking speed of 100 rpm, with a slope of 10°and particle size less than 75 μm.
基金Supported by the National "305" Project(2001BA609A-07-08)Innovative Project of CAS(KZCX1-Y-03-01)
文摘Altai polymetallic mineralization belt is famous copper-polymetallic mineralization belt in the world. There are a lot of gold deposits in the Altai ore belt in Xinjiang, China. These gold deposits belong to two genetic types: volcanogene late-stage hydrothermal type and fractured altered rock type. The authors discuss mainly the geological and mineralized features of fractured altered rock type of gold deposits in Altai gold ore belt. Base on this study, the metallogenic law is summarized and the deep metallogenic prognosis has been done in Duolanasayi and Tuokuzibayi gold deposits, and some mineralized anomalys have been discovered.
基金supported by the Fundamental Research Funds for the Central Universities(2022QN1005)
文摘To overcome the limitations of geography,climate,and ore characteristics on the ore beneficiation process,biooxidation studies on low-grade arsenic-bearing refractory gold ore by pool leaching were carried out,as well as process fitting analysis.The gold particles are encapsulated by pyrite and arsenopyrite.After 60 days of biooxidation,the oxidation rates of arsenic,sulfur,and gold were 39%~69%,24%~41%,and 49%~83%,respectively.The inoculated Acidithiobacillus ferrooxidans,Ferroplasma acidiphilum,and Leptospirillum ferrodiazotrophum could all mediate the initial pyrite/arsenopyrite oxidation and the Fe^(2+)oxidation reaction,but only the former could mediate the subsequent sulfur compound oxidation.When compared to daily bacterial circulation and bacterial replacement every ten days,aeration improved the gold leaching rate by 14%~22%.The Boltzmann model could fit both the arsenic and sulfur bio-oxidation,with model fit variances greater than 0.98.Based on the experimental and fitting results,the bio-oxidation cycle was determined to be 60 days,and the bio-oxidation mechanisms are summarized.This study has significant practical implications for the rational utilization of gold resources and provides theoretical and practical guidance for similar gold ores.
