In order to better understand the leaching process of rare earth （RE） and aluminum （Al） from the weathered crust elutiondepositedRE ore, the mass transfer of RE and Al in column leaching was investigated using the...In order to better understand the leaching process of rare earth （RE） and aluminum （Al） from the weathered crust elutiondepositedRE ore, the mass transfer of RE and Al in column leaching was investigated using the chromatographic plate theory. Theresults show that a higher initial ammonium concentration in a certain range can enhance the mass transfer process. pH of leachingagent in the range of 2 to 8 almost has no effect on the mass transfer efficiency of RE, but plays a positive role in the mass transferefficiency of Al under strong acidic condition （pH〈4）. There is an optimum flow rate that makes the highest mass transfer efficiency.The optimum leaching condition of RE is the leaching agent pH of 4？8, ammonium concentration of 0.4 mol/L and flow rate of0.5 mL/min. The mass transfer efficiencies of RE and Al both follow the order： （NH4）2SO4〈NH4Cl〈NH4NO3, implying thecomplexing ability of anion.展开更多
The ion exchange model of the leaching process was determined via batch leaching experiments using the Kerr model, with the selectivity coefficient experimentally determined to be 12.59×10^-10 L^2/g^2. Solute tra...The ion exchange model of the leaching process was determined via batch leaching experiments using the Kerr model, with the selectivity coefficient experimentally determined to be 12.59×10^-10 L^2/g^2. Solute transport laws of ammonium ions (NH4 +) and rare earth ions (RE^3+) in column leaching were described by the convection-dispersion equation (CDE). The source and sink in the CDE were determined by the Kerr model. The CDE with strong nonlinearity was solved using the sequential non-iterative method. Compared with the breakthrough curve of RE^3+, the correlation coefficient between the simulated and experimental curves reached 0.8724. Therefore, this method can simulate the one-dimensional column leaching of weathered crust elution-deposited rare earth ore. Moreover, the effects of different concentrations of ammonium sulfate ((NH4)2SO4) solution on the leaching rate of rare earth were analyzed. The optimal concentration of the (NH4)2SO4 solution had a linear relationship with the rare earth grade.展开更多
The dynamic leaching of lanthanides from a west desert phosphate ore, Egypt (Abu Tartur) by hydrochloric acid, nitric acid and sulfuric acid solutions was investigated in this study as a function of acid concentration...The dynamic leaching of lanthanides from a west desert phosphate ore, Egypt (Abu Tartur) by hydrochloric acid, nitric acid and sulfuric acid solutions was investigated in this study as a function of acid concentration, flow rate and the presence of some additives such as boric acid. Also the kinetics of leaching of lanthanides was investigated as a function of temperature. It was found that the leaching process could be described by a shrinking-core model, with activation energy about 5.9, 13.8 and 21.9 kJ/...展开更多
For the low-grade copper sulfide ores with 0.99% of copper, of which 41.5% was primary copper sulfide, and 54.5% was secondary copper sulfide, well-controlled column bioleaching on a novel equipment was carried out to...For the low-grade copper sulfide ores with 0.99% of copper, of which 41.5% was primary copper sulfide, and 54.5% was secondary copper sulfide, well-controlled column bioleaching on a novel equipment was carried out to investigate the optimal conditions of pre-leaching, particle sizes of ores, temperature, spray intensity and strain consortium. Results show that copper extraction of 91.11% can be obtained after 90 d with the optimal p H value of pre-leaching of 0.8; the p H values of pre-leaching significantly affect the final copper extractions. Copper extractions of 93.11%, 91.04% and 80.45% can be obtained for the bioleaching of ores with particles size of 5-8 mm, 5-15 mm and 5-20 mm, respectively. Copper extractions are 83.77% and 91.02% for bioleaching under the conditions of room temperature and 35 oC. Copper extractions are 77.25%, 85.45% and 91.12% for the bioleaching when flow rate of spray was 5 L/（h·m2）, 10 L/（h·m2） and 15 L/（h·m2）, respectively. Additionally, the strain consortium C3 is the best among the four strain consortia in bioleaching. By considering the energy consumption, the optimal conditions of bioleaching in this work are determined as p H of pre-leaching of 0.8, particles size of 5-15 mm, temperature of 35 ℃, spray intensity of 15 L/（h·m2）, and strain consortium C3.展开更多
In this paper,a multi-stage leaching process for the weathered crust elution-deposited rare earth ore was proposed using MgSO_(4)as a leaching agent.The results indicate that with increasing the concentration of MgSO_...In this paper,a multi-stage leaching process for the weathered crust elution-deposited rare earth ore was proposed using MgSO_(4)as a leaching agent.The results indicate that with increasing the concentration of MgSO_(4)from 0.5 wt%-1.0 wt%to 2.0 wt%-4.0 wt%,the peak concentrations of rare earths increase from 1.87 to 3.59 to 5.49-10.21 g/L,and the collection periods of leach solution are sho rtened from 0.85 to 1.54 to 0.31-0.47(liquid-to-ore ratio).When the rare earth ore is leached with leaching agent solution with high initial pH(3.0-5.0),the rare earths and aluminum are predominantly leached by Mg^(2+)instead of H+.However,H+participate in the leaching process of rare earths and aluminum at lower initial pH(1.5-3.0)of the leaching agent solution.Especially,when the initial pH of leaching agent solution is 2.0,a large amount of aluminum is leached when the liquid-to-ore ratio is greater than 1.2.Based on the above insights,increasing the initial pH(3.0-5.0)of leaching agent solution in the injection stage using high-concentration MgSO_(4)(>1.0 wt%)can increase the peak concentration of rare earths in the leach solution and shorten the collection period.However,in the injection stage using low MgSO_(4)concentration(<1.0 wt%),an initial pH of leaching agent solution of 2.0 is selected to reduce the leaching amount of aluminum and the consumption of MgSO_(4).Comparing to the Leaching process using constant MgSO_(4)concentration(2.0 wt%,initial pH of 5.0),the leaching efficiency of rare earths using a multi-stage leaching process is approximately equal(about 94.6%)under optimal conditions.The leaching amount of aluminum is reduced by 16.9%.The consumption of MgSO_(4)is reduced by 67.1%.展开更多
The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolip...The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolipid and non-ionic biosurfactant saponin were used as washing solutions. Soil properties and the rare earth element fractions were analysed to define the effect of leaching on soil and elemental speciation. Column leaching results showed that saponin solution was more effective than rhamnolipid in the removal of the four rare earth elements tested, with the accumulative removal efficiency of La, Ce, Y and Eu following flushing with 400 mL of 25 g/L saponin, reaching 35.258%, 26.072%, 31.476% and 30.849%, respectively. The change in REE speciation showed that REE removed from soils were mainly derived from the acid-soluble and residual fractions released when rhamnolipid solution was used as a leaching agent. However, for saponin leaching, removed REE amounts were derived from acid-soluble and reducible fractions. Complexation interactions were identified between saponin and REEs, according to infrared spectroscopy and ion exchange data, with saponin complexing with La, Ce, Y, and Eu at a complex ratio of 1：1.展开更多
Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV(vs.SHE) and different temperatures of 30 and 60℃.For sterile experiments,the redox potential of ir...Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV(vs.SHE) and different temperatures of 30 and 60℃.For sterile experiments,the redox potential of irrigation solution was controlled by adding hydrogen peroxide solution(15 wt%),while the redox potential of irrigation solution for bioleaching was elevated by flowing through the packed bed in which bacteria were activated and colonized.The rate of pyrite bioleaching is faster than that of sterile oxidation at temperature of 30℃.The reason is that the potential gradient of leaching solution in bioleaching column is much smaller than that in sterile column.The redox potentials of irrigation solution and leaching solution are similar for bioleaching;however,the redox potential difference of irrigation solution and leaching solution for sterile oxidation is about 150 mV.When temperature increases to 60℃ for sterile oxidation,the rate of pyrite leaching is faster than that of bioleaching at temperature of 30℃,even though the redox potential gradient of leaching solution is great.The mineralogy analyses of pyrite residue were performed by scanning electron microscopy-energy-dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analyses.The results confirm that pyrite oxidation might only occur at specific sites with high surface energy on surface and obeys the "indirect mechanism" whether there are bacteria or not.The pyrite oxidation rate is not inhibited by inert sulfur on residue surface at elevated redox potential.According to the conclusions,the way to accelerate pyrite oxidation is proposed.展开更多
Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural so...Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural soils. We conducted a soil column leaching experiment to study the effects of BF on the leaching of total nitrogen(TN), total phosphorus, and total potassium(TK) in tobacco soils. The distribution characteristics of NH_4^+-N, available P, and available K in soil profiles were analyzed after the application of BF. Biochar was prepared by pyrolysis of fluecured tobacco stems. It was applied at four levels, 0%, 3%,9%, and 15%(w/w), respectively, to the compound fertilizer. Compared with the control, the leaching loss of soil TN decreased by 8.36%, 6.72%, and 6.45%, and the loss of soil TK decreased by 9.18%, 9.31% and 11.82% in the 3%,9%, and 15% BF treatments, respectively. However, BF had no significant effect on the P leaching due to the low movement of P in the soil profile. In addition, the BF addition increased the immobilization of NH_4^+-N, available P, and available K in the soil profile. These results indicate that addition of BF to a tobacco-planting soil reduced nutrient leaching, and suggest that BF could be an effective method of applying biochar to agriculture fields.展开更多
The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanx...The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.展开更多
Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the...Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.展开更多
The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validat...The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validation of their passivation competence as soil remediation agents by examining the multifaceted role of potassium-silicon-calcium mineral fertilizer combined with rice husk-based biochar generated at different pyrolysis temperatures.The soil leaching column experiment,conducted based on the adsorption experiments,has facilitated our scrutiny of the passivation impacts of cadmium(Cd)and lead(Pb)when introducing different proportions of mineral fertilizers and biochar into the soil.These results indicate that biochar’s adsorption efficiency for Cd and Pb is significantly improved at escalated pyrolytic temperature conditions in a single solution.The biochar generated at 700℃(C700)renders adsorption effectiveness of approximately 84.24%for Cd and 99.74%for Pb.Biochar conspicuously registers superior adsorption efficiency towards Pb relative to Cd.The mineral fertilizer,which achieves an adsorption efficiency of 97.76%for Cd,is identified as the main adsorbent for Cd,although its competence is slightly lower compared to C700 for Pb adsorption.Within a complex solution,biochar and mineral fertilizer show reduced Cd and Pb adsorption levels compared to single solutions.There is a keen competition for adsorption surfaces witnessed between Cd and Pb,with Pb’s distribution coefficient(Kd)notably outpacing that of Cd.The isothermal adsorption analyses depict that the mineral fertilizer follows the Langmuir model for Cd adsorption,while C700 conveys the Freundlich model for Pb adsorption.The soil leaching column experiment’s results signify that the composite passivation agents significantly outperform the individual passivation agents in efficiency.The combined application of biochar and mineral fertilizer minimizes the cumulative leaching of Cd and Pb,with the optimal soil remedy proportion for heavy metal contamination being 7∶3.In practical application,mindful consideration should be accorded to the deployment ratios of different passivation agents.展开更多
In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed colum...In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed columns and various aqueous media (H2O-milliQ, NaOH, HCl, SDS, Triton X-114, Humic acids and Acetonitrile). The leachate samples were analyzed on an Agilent Technologies 6890N Gas Chromatograph with electron capture in a# AB002 Column 30.0 m × 250 μm × 0.25 μm calibrated, 25 psi pressure, flow 2.9 ml/min, temperature 25°C, ultra-high purity Helium as the entrainment gas and an elution time of 50 min. The results show that the highest extraction percentage of pollutants in the soil washing was obtained with acetonitrile recovering: p, p’-DDT (91.0%);p, p’-DDE (92.0%);p, p’-DDD (96.0%);aldrin (98.6%);dieldrin (98.0%). With Triton X-114, the extractions recovery was: p, p’-DDT (63.0%);p, p’-DDE (64.0%);p, p’-DDD (65.0%);aldrin (67.0%);dieldrin (72.0%). This study illustrates the potential Applicability of SPME for routine analysis of organochlorine pesticides in soils.展开更多
基金Projects(51274152,41472071)supported by the National Natural Science Foundation of ChinaProject(T201506)supported by the Program for Excellent Young Scientific and Technological Innovation Team of Hubei Provincial Department of Education,China
文摘In order to better understand the leaching process of rare earth （RE） and aluminum （Al） from the weathered crust elutiondepositedRE ore, the mass transfer of RE and Al in column leaching was investigated using the chromatographic plate theory. Theresults show that a higher initial ammonium concentration in a certain range can enhance the mass transfer process. pH of leachingagent in the range of 2 to 8 almost has no effect on the mass transfer efficiency of RE, but plays a positive role in the mass transferefficiency of Al under strong acidic condition （pH〈4）. There is an optimum flow rate that makes the highest mass transfer efficiency.The optimum leaching condition of RE is the leaching agent pH of 4？8, ammonium concentration of 0.4 mol/L and flow rate of0.5 mL/min. The mass transfer efficiencies of RE and Al both follow the order： （NH4）2SO4〈NH4Cl〈NH4NO3, implying thecomplexing ability of anion.
基金Projects(51664015,41602311,51774156) supported by the National Natural Science Foundation of China
文摘The ion exchange model of the leaching process was determined via batch leaching experiments using the Kerr model, with the selectivity coefficient experimentally determined to be 12.59×10^-10 L^2/g^2. Solute transport laws of ammonium ions (NH4 +) and rare earth ions (RE^3+) in column leaching were described by the convection-dispersion equation (CDE). The source and sink in the CDE were determined by the Kerr model. The CDE with strong nonlinearity was solved using the sequential non-iterative method. Compared with the breakthrough curve of RE^3+, the correlation coefficient between the simulated and experimental curves reached 0.8724. Therefore, this method can simulate the one-dimensional column leaching of weathered crust elution-deposited rare earth ore. Moreover, the effects of different concentrations of ammonium sulfate ((NH4)2SO4) solution on the leaching rate of rare earth were analyzed. The optimal concentration of the (NH4)2SO4 solution had a linear relationship with the rare earth grade.
文摘The dynamic leaching of lanthanides from a west desert phosphate ore, Egypt (Abu Tartur) by hydrochloric acid, nitric acid and sulfuric acid solutions was investigated in this study as a function of acid concentration, flow rate and the presence of some additives such as boric acid. Also the kinetics of leaching of lanthanides was investigated as a function of temperature. It was found that the leaching process could be described by a shrinking-core model, with activation energy about 5.9, 13.8 and 21.9 kJ/...
基金Projects(51374248,51320105006) supported by National Natural Science Foundation of ChinaProject(NCET-13-0595) supported by the Program for New Century Excellent Talents in University,ChinaProject(2014T70692) supported by the China Postdoctoral Science Foundation
文摘For the low-grade copper sulfide ores with 0.99% of copper, of which 41.5% was primary copper sulfide, and 54.5% was secondary copper sulfide, well-controlled column bioleaching on a novel equipment was carried out to investigate the optimal conditions of pre-leaching, particle sizes of ores, temperature, spray intensity and strain consortium. Results show that copper extraction of 91.11% can be obtained after 90 d with the optimal p H value of pre-leaching of 0.8; the p H values of pre-leaching significantly affect the final copper extractions. Copper extractions of 93.11%, 91.04% and 80.45% can be obtained for the bioleaching of ores with particles size of 5-8 mm, 5-15 mm and 5-20 mm, respectively. Copper extractions are 83.77% and 91.02% for bioleaching under the conditions of room temperature and 35 oC. Copper extractions are 77.25%, 85.45% and 91.12% for the bioleaching when flow rate of spray was 5 L/（h·m2）, 10 L/（h·m2） and 15 L/（h·m2）, respectively. Additionally, the strain consortium C3 is the best among the four strain consortia in bioleaching. By considering the energy consumption, the optimal conditions of bioleaching in this work are determined as p H of pre-leaching of 0.8, particles size of 5-15 mm, temperature of 35 ℃, spray intensity of 15 L/（h·m2）, and strain consortium C3.
基金Project supported by the Major Research Plan of the National Natural Science Foundation of China(91962211)the National Key Research and Development Program of China(2021YFC2902202)+2 种基金the Science and Technology Innovation Fund of GRINM(2022PD0102)the Major Program of Qingyuan Innovation Laboratory(00122004)the Beijing Nova Program(20230484379)。
文摘In this paper,a multi-stage leaching process for the weathered crust elution-deposited rare earth ore was proposed using MgSO_(4)as a leaching agent.The results indicate that with increasing the concentration of MgSO_(4)from 0.5 wt%-1.0 wt%to 2.0 wt%-4.0 wt%,the peak concentrations of rare earths increase from 1.87 to 3.59 to 5.49-10.21 g/L,and the collection periods of leach solution are sho rtened from 0.85 to 1.54 to 0.31-0.47(liquid-to-ore ratio).When the rare earth ore is leached with leaching agent solution with high initial pH(3.0-5.0),the rare earths and aluminum are predominantly leached by Mg^(2+)instead of H+.However,H+participate in the leaching process of rare earths and aluminum at lower initial pH(1.5-3.0)of the leaching agent solution.Especially,when the initial pH of leaching agent solution is 2.0,a large amount of aluminum is leached when the liquid-to-ore ratio is greater than 1.2.Based on the above insights,increasing the initial pH(3.0-5.0)of leaching agent solution in the injection stage using high-concentration MgSO_(4)(>1.0 wt%)can increase the peak concentration of rare earths in the leach solution and shorten the collection period.However,in the injection stage using low MgSO_(4)concentration(<1.0 wt%),an initial pH of leaching agent solution of 2.0 is selected to reduce the leaching amount of aluminum and the consumption of MgSO_(4).Comparing to the Leaching process using constant MgSO_(4)concentration(2.0 wt%,initial pH of 5.0),the leaching efficiency of rare earths using a multi-stage leaching process is approximately equal(about 94.6%)under optimal conditions.The leaching amount of aluminum is reduced by 16.9%.The consumption of MgSO_(4)is reduced by 67.1%.
基金Project(50621063)supported by the National Natural Science Foundation of ChinaProject(2004CB619205)supported by the National Basic Research Program of ChinaProject(2007AA060902)supported by the High-tech Research and Development Program of China
基金supported by“Twelfth five-year”National Science and Technology Support Program(2012BAC11B07)National Natural Science Foundation of China(51664024)+1 种基金Outstanding Doctoral Dissertation Project Funding of Jiangxi University of Science and Technology(YB2016003)Talent Project of Jiangxi Province's Innovation-drive“5511”Program(20165BCB18013)
文摘The effective leaching of rare earth elements（La, Ce, Y and Eu） from simulated contaminated soil using bio-surfactant was investigated in a lab-scale column leaching experiment, where anionic biosurfactant rhamnolipid and non-ionic biosurfactant saponin were used as washing solutions. Soil properties and the rare earth element fractions were analysed to define the effect of leaching on soil and elemental speciation. Column leaching results showed that saponin solution was more effective than rhamnolipid in the removal of the four rare earth elements tested, with the accumulative removal efficiency of La, Ce, Y and Eu following flushing with 400 mL of 25 g/L saponin, reaching 35.258%, 26.072%, 31.476% and 30.849%, respectively. The change in REE speciation showed that REE removed from soils were mainly derived from the acid-soluble and residual fractions released when rhamnolipid solution was used as a leaching agent. However, for saponin leaching, removed REE amounts were derived from acid-soluble and reducible fractions. Complexation interactions were identified between saponin and REEs, according to infrared spectroscopy and ion exchange data, with saponin complexing with La, Ce, Y, and Eu at a complex ratio of 1：1.
基金financially supported by the Research Fund for Program of Efficient Gold Extraction from Refractory Gold Ore of Sichuan Province,China (No.12120113088100)the National Natural Science Foundation of China (Nos.41401541 and 51474075)the Bureau of International Co-operation,Chinese Academy of Sciences (No.122111KYSB20150013)
文摘Comparisons on the bioleaching and sterile oxidation of pyrite were performed at controlled redox potential of 900 mV(vs.SHE) and different temperatures of 30 and 60℃.For sterile experiments,the redox potential of irrigation solution was controlled by adding hydrogen peroxide solution(15 wt%),while the redox potential of irrigation solution for bioleaching was elevated by flowing through the packed bed in which bacteria were activated and colonized.The rate of pyrite bioleaching is faster than that of sterile oxidation at temperature of 30℃.The reason is that the potential gradient of leaching solution in bioleaching column is much smaller than that in sterile column.The redox potentials of irrigation solution and leaching solution are similar for bioleaching;however,the redox potential difference of irrigation solution and leaching solution for sterile oxidation is about 150 mV.When temperature increases to 60℃ for sterile oxidation,the rate of pyrite leaching is faster than that of bioleaching at temperature of 30℃,even though the redox potential gradient of leaching solution is great.The mineralogy analyses of pyrite residue were performed by scanning electron microscopy-energy-dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analyses.The results confirm that pyrite oxidation might only occur at specific sites with high surface energy on surface and obeys the "indirect mechanism" whether there are bacteria or not.The pyrite oxidation rate is not inhibited by inert sulfur on residue surface at elevated redox potential.According to the conclusions,the way to accelerate pyrite oxidation is proposed.
基金supported by the National Natural Science Foundation of China (Nos. 41773144 U1612441+5 种基金 41503080)the Key Technologies R&D Project in Agriculture of Guizhou province (Nos. NY [2013] 3019 NY [2015] 3001-1)the Major S&T Special Project of Guizhou province (No. [2014] 6015-21)the Opening Fund of the State Key Laboratory of Environmental Geochemistry (SKLEG2018905)Innovative Plan of Guizhou province and the Science and Technology Project of Guizhou Tobacco Company (201614)
文摘Biochar is a soil amendment for increasing soil quality and decreasing nutrient leaching. However, there is little information on the impact of biochar-based fertilizer(BF) on soil nutrient leaching in agricultural soils. We conducted a soil column leaching experiment to study the effects of BF on the leaching of total nitrogen(TN), total phosphorus, and total potassium(TK) in tobacco soils. The distribution characteristics of NH_4^+-N, available P, and available K in soil profiles were analyzed after the application of BF. Biochar was prepared by pyrolysis of fluecured tobacco stems. It was applied at four levels, 0%, 3%,9%, and 15%(w/w), respectively, to the compound fertilizer. Compared with the control, the leaching loss of soil TN decreased by 8.36%, 6.72%, and 6.45%, and the loss of soil TK decreased by 9.18%, 9.31% and 11.82% in the 3%,9%, and 15% BF treatments, respectively. However, BF had no significant effect on the P leaching due to the low movement of P in the soil profile. In addition, the BF addition increased the immobilization of NH_4^+-N, available P, and available K in the soil profile. These results indicate that addition of BF to a tobacco-planting soil reduced nutrient leaching, and suggest that BF could be an effective method of applying biochar to agriculture fields.
基金financially supported by the National Natural Science Foundation of China(Nos.41120124003 and 41372251)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20130145120014)+1 种基金the Natural Science Foundation of Hubei Province,China(No.2013CFB41)the Opening Fund of State Key Laboratory of Geohazard Prevention and Geoenvironment Protection(Chengdu University of Technology)(No.SKLGP2012K022)
文摘The long-term dumping of coal waste piles has caused serious environmental problems. Release of trace elements（including rare earth elements, REEs） from coal spoils gobs was investigated at Yangquan coal mine, Shanxi Province, China. X-ray diffraction（XRD） was used to analyze the mineral composition of the coal spoils. The minerals of the coal-spoil samples are mainly kaolinite and quartz, with a minor proportion of pyrite. The batch and column tests were employed to simulate the leaching behavior of trace elements from coal spoils. Elements V, Cr, Zn, As, Pb, and Cd are highly enriched in all coal spoils. The coal spoils also have elevated levels of Ga, Ge, Se, Sn, Hf, and Th. The leachate of coal spoils, fried coal spoils and CSFGM（coal spoils fire gas mineral） samples are acidic, with the p H values ranging between 3.0 and 6.6. The released elements with high concentrations（over 100 μg/L） include Fe, Mn, Co, Ni and Zn, while moderately-released elements are Cu, Se, Mo and As. A high content of heavy metals in batch-test leachate with CSFGM indicates an increased mobility of heavy metals in coal spoil combustion byproduct. Within the first hour washing with the electrolyte solution, a rapid rise of common cations, trace elements, and REEs content, as well as a drop of p H value, in effluent was observed. An increased leaching velocity favors the release of trace elements from coal spoils. In addition, the pulse input of precipitation led to more elements to be released than continuous leaching.
文摘Heap leaching is a promising, less costly, alternative technology for processing low grade gold ores compared with traditional, energy intensive processes (e.g. autoclave/tank leaching). This research investigated the effectiveness of lime for enhancing gold leaching rates of gold ores from ajialongwa gold mine in china. Column and heaping experiments were performed using cyanide leaching solutions at pH=10, with and without lime (CaO). The presence of lime greatly increased gold leaching rates. Column leaching experiments showed without the addition of lime, there was 35.2% of gold leached. The addition of lime resulted in the release of 50.56% gold. Lime assisted cyanide of refractory gold was proved by heap leaching experiments.
基金supported by the National Natural Science Foundation of Sichuan Province(22NSFSC0191,22NSFSC3990)。
文摘The combined application of mineral fertilizer and biochar significantly improves the passivation of heavy metal-contaminated soil,surpassing the effects of individual application.This study has reinforced the validation of their passivation competence as soil remediation agents by examining the multifaceted role of potassium-silicon-calcium mineral fertilizer combined with rice husk-based biochar generated at different pyrolysis temperatures.The soil leaching column experiment,conducted based on the adsorption experiments,has facilitated our scrutiny of the passivation impacts of cadmium(Cd)and lead(Pb)when introducing different proportions of mineral fertilizers and biochar into the soil.These results indicate that biochar’s adsorption efficiency for Cd and Pb is significantly improved at escalated pyrolytic temperature conditions in a single solution.The biochar generated at 700℃(C700)renders adsorption effectiveness of approximately 84.24%for Cd and 99.74%for Pb.Biochar conspicuously registers superior adsorption efficiency towards Pb relative to Cd.The mineral fertilizer,which achieves an adsorption efficiency of 97.76%for Cd,is identified as the main adsorbent for Cd,although its competence is slightly lower compared to C700 for Pb adsorption.Within a complex solution,biochar and mineral fertilizer show reduced Cd and Pb adsorption levels compared to single solutions.There is a keen competition for adsorption surfaces witnessed between Cd and Pb,with Pb’s distribution coefficient(Kd)notably outpacing that of Cd.The isothermal adsorption analyses depict that the mineral fertilizer follows the Langmuir model for Cd adsorption,while C700 conveys the Freundlich model for Pb adsorption.The soil leaching column experiment’s results signify that the composite passivation agents significantly outperform the individual passivation agents in efficiency.The combined application of biochar and mineral fertilizer minimizes the cumulative leaching of Cd and Pb,with the optimal soil remedy proportion for heavy metal contamination being 7∶3.In practical application,mindful consideration should be accorded to the deployment ratios of different passivation agents.
文摘In this study, it is reported an analytical approach to recover organochlorine pesticides from a clay soil. Soil was physical and chemically characterized. Also pesticides extraction was carried out using packed columns and various aqueous media (H2O-milliQ, NaOH, HCl, SDS, Triton X-114, Humic acids and Acetonitrile). The leachate samples were analyzed on an Agilent Technologies 6890N Gas Chromatograph with electron capture in a# AB002 Column 30.0 m × 250 μm × 0.25 μm calibrated, 25 psi pressure, flow 2.9 ml/min, temperature 25°C, ultra-high purity Helium as the entrainment gas and an elution time of 50 min. The results show that the highest extraction percentage of pollutants in the soil washing was obtained with acetonitrile recovering: p, p’-DDT (91.0%);p, p’-DDE (92.0%);p, p’-DDD (96.0%);aldrin (98.6%);dieldrin (98.0%). With Triton X-114, the extractions recovery was: p, p’-DDT (63.0%);p, p’-DDE (64.0%);p, p’-DDD (65.0%);aldrin (67.0%);dieldrin (72.0%). This study illustrates the potential Applicability of SPME for routine analysis of organochlorine pesticides in soils.
