Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water conten...Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.展开更多
Driven by rapid technological advancements and economic growth,mineral extraction and metal refining have increased dramatically,generating huge volumes of tailings and mine waste(TMWs).Investigating the morphological...Driven by rapid technological advancements and economic growth,mineral extraction and metal refining have increased dramatically,generating huge volumes of tailings and mine waste(TMWs).Investigating the morphological fractions of heavy metals and metalloids(HMMs)in TMWs is key to evaluating their leaching potential into the environment;however,traditional experiments are time-consuming and labor-intensive.In this study,10 machine learning(ML)algorithms were used and compared for rapidly predicting the morphological fractions of HMMs in TMWs.A dataset comprising 2376 data points was used,with mineral composition,elemental properties,and total concentration used as inputs and concentration of morphological fraction used as output.After grid search optimization,the extra tree model performed the best,achieving coefficient of determination(R2)of 0.946 and 0.942 on the validation and test sets,respectively.Electronegativity was found to have the greatest impact on the morphological fraction.The models’performance was enhanced by applying an ensemble method to the top three optimal ML models,including gradient boosting decision tree,extra trees and categorical boosting.Overall,the proposed framework can accurately predict the concentrations of different morphological fractions of HMMs in TMWs.This approach can minimize detection time,aid in the safe management and recovery of TMWs.展开更多
Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize th...Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize the resource utilization of magnesium slag(MS)and blast furnace slag(BFS),the effects of different contents of MS and BFS as partial CSs on the deformation and energy characteristics of cemented tailings backfill on different curing ages(3,7,and 28 d)were discussed.Meanwhile,the destabilization failure energy criterion of the backfill was established from the direction of energy change.The results show that the strength of all backfills increased with increasing curing age,and the strengths of the backfills exceeded 1.342 MPa on day 28.The backfill with 50%BFS+50%cement has the best performance in mechanical properties(the maximum strength can reach 6.129 MPa)and is the best choice among these CS combinations.The trend in peak strain and elastic modulus of the backfill with increasing curing age may vary depending on the CS combination.The energy index at peak stress of the backfill with BFS as a partial CS was significantly higher than that of the backfill under other CS combinations.In contrast,the enhancement of the energy index when MS was used as a partial CS was not as significant as BFS.Sharp changes in the energy consumption ratio after continuous smooth changes can be used as a criterion for destabilization and failure of the backfill.The research results can provide guidance for the application of MS and BFS as partial CSs in mine filling.展开更多
The distribution of tailings lenticles reflects the sediment state of tailing dam, and has a great influence on the stability of the dam. In order to disclose the distribution law of tailings lenticles in theory, 12 g...The distribution of tailings lenticles reflects the sediment state of tailing dam, and has a great influence on the stability of the dam. In order to disclose the distribution law of tailings lenticles in theory, 12 geological cross-sections, including 7 cross-sections of tailings dam constructed by the upstream method and 5 cross-sections by the middle line method, were analyzed with box dimension method. The results show that the distribution of tailings lenticles has better fractal character with box dimension from 1.290 7 to 1.513 6. The box dimension of the tailings dam constructed by upstream method is nearly 1.50 and that by middle line method is 1.30. Thereby the values of lenticles dimension have obvious relation to the method of constructing dam, and reflect the sediment state of tailings dam with the rule that smaller value means better state.展开更多
The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship amo...The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters. They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine.展开更多
A new technology characterized by rapidly non-mechanical settlement of unclassified tailings was developed based on a large number of tests, and dynamic settlement and continual slurry preparation without hardening in...A new technology characterized by rapidly non-mechanical settlement of unclassified tailings was developed based on a large number of tests, and dynamic settlement and continual slurry preparation without hardening in vertical sand silo were eventually realized by the addition of an effective flocculating agent (NPA). The results show that the sedimentation velocity of interface between unclassified tailings and water after the addition of NPA increases by 10-20 times, the sedimentation mass fraction of unclassified tailings at the bottom of vertical sand silo is up to 64%, the solid particle content of waste water meets the national standard, and the side influences of NPA can be removed by the addition of fly ash. The industrial test result shows that the system, the addition manner and the equipments are rational, and the vertical sand silo is used efficiently. This developed system is simple with large throughput, and the processing cost is 2.2 yuan(RMB)/m3, only 10%-20% of that by mechanical settlement.展开更多
Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-ag...Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.展开更多
Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process ca...Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.展开更多
It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformat...It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformation properties of CTB was examined and discussed.Results indicate that the triaxial compressive and deformation behavior of CTB is strongly affected by the cement content,curing age and confining pressure.The increase in cement content,curing age and confining pressure leads to a change in stress−strain behavior and an increase in the axial strain at failure and post-peak strength loss.The cohesion of CTB rises as the curing age and cement content increase.However,the enhancement in internal friction angle is trivial and negligible.It should be noted that the failure pattern of CTB samples in triaxial compression is mainly along a shear plane,the confining pressure restrains the lateral expansion and the bulging failure pattern is dominantly detected in CTB samples as curing age length and cement content increase.The results will help to better understand the triaxial mechanical and deformation behavior of CTB.展开更多
In order to develop the applications of ore tailings, the glass ceramics were prepared by using a conventional melting-quenching-sintering process. The phase component, microstructures, magnetic properties and thermal...In order to develop the applications of ore tailings, the glass ceramics were prepared by using a conventional melting-quenching-sintering process. The phase component, microstructures, magnetic properties and thermal conductivities of the prepared glass ceramics were investigated by using X-ray diffractometer, scanning electron microscopy, vibrating sample magnetometer and thermophysical properties tester, respectively. The results show that orthorhombic olivine-type phase and triclinic sunstone-type phase formed when the glass was annealed at 700 oC, the concentration of olivine-type and sunstone-type phases decreased, the spinel-type cubic phase occurred and the amount increased when the annealing temperatures increased. The magnetic properties from the cubic spinel ferrites were detected in the glass ceramics, and the related saturation magnetization increased with the annealing temperature increasing. The porous glass ceramics with magnetic property showed much lower thermal conductivity, compared with the non-magnetic porous glass-ceramic and the dense glass-ceramics.展开更多
Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation wer...Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation were also investigated in the current study.The flocculation mechanism of the flocculant on tailings was investigated using zeta potential and Fourier transform infrared(FTIR)measurements.The results obtained reveal that 1)sodium silicate gel,used as a binder for the consolidation of tailings form primary flocs,acts as an anchor and the adsorption of polymer flocculant on these anchors results in the formation of larger flocs and,consequently,enhanced settling rate;2)flocculation in the presence of silica gel and polymer has a faster settling rate than single-polymer flocculation owing to the mechanisms of charge neutralization and bridging as identified using zeta potential and FTIR measurements.A pilot level study was conducted to investigate the influence of processed water on the flotation of scheelite.The results show that the proposed tailing disposal method could improve scheelite recovery by 2%(approximately)and could reduce the daily operation costs of the plant by approximately 108.57 USD.展开更多
The effect of sulfur addition/solids content(SA/SC)ratio on heavy metals(e.g.copper,zinc and lead)obtained from mine tailings by indigenous sulfur-oxidizing bacteria was studied,and the changes in the chemical forms o...The effect of sulfur addition/solids content(SA/SC)ratio on heavy metals(e.g.copper,zinc and lead)obtained from mine tailings by indigenous sulfur-oxidizing bacteria was studied,and the changes in the chemical forms of heavy metals after bioleaching were explored.The results show that the solubilization of metals is significantly influenced by SA/SC ratio,and SA/SC ratio of 2.50 is found to be the best for bacterial activity and metal solubilization among six SA/SC ratios tested(such as 1.00,1.33,1.50,1.67,2.00 and 2.50)under the chosen experimental conditions.The pH decreases fast and the maximum solubilizations of copper and zinc are respectively 81.76% and 84.35% while that of lead only reaches 40.36%.After bioleaching,the chemical forms of heavy metals have changed.The metals remained in mine tailings are mainly found in residual fractions,which is harmless to the surrounding environment.展开更多
Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for...Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diffusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam’s acceleration, seismic dynamic stress and pore water pressure were obtained. The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly. The interior stress is compressive stress, the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method. The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams’ stability during earthquake is secondary reason.展开更多
The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geop...The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geopolymers with compressive strength of 38.8 MPa were prepared by using phosphate tailings as the main raw material,fly ash as the active silicon-aluminum material,and water glass as the alkaline activator.The solid content of phosphate tailings and fly ash was 60%and 40%,respectively,and the water-cement ratio was 0.22.The results of XRD,FTIR,SEM-EDS and XPS show that the reactivity of phosphate tailings with alkaline activator is weak,and the silicon-aluminum material can react with alkaline activator to form zeolite and gel,and encapsulate/cover the phosphate tailings to form a dense phosphate tailings-based geopolymer.During the formation of geopolymers,part of the aluminum-oxygen tetrahedron replaced the silicon-oxygen tetrahedron,causing the polycondensation reaction between geopolymers and increasing the strength of geopolymers.The leaching toxicity test results show that the geopolymer has a good solid sealing effect on heavy metal ions.The preparation of geopolymer from phosphate tailings is an important way to alleviate the storage pressure and realize the resource utilization of phosphate tailings.展开更多
Based on the collaborative exploitation of deep mineral resources and geothermal resources, the thermal accumulation process of cemented tailings backfill(CTB) was studied by numerical simulation. The effects of therm...Based on the collaborative exploitation of deep mineral resources and geothermal resources, the thermal accumulation process of cemented tailings backfill(CTB) was studied by numerical simulation. The effects of thermal accumulation time, slurry proportions and temperature conditions on the thermal accumulation of backfill are analyzed, the influence of the heat conduction between backfill and surrounding rock, the heat convection between backfill and airflow on thermal accumulation were compared simultaneously. The results show that the total thermal accumulation capacity increases by approximately 85% within 10-90 d. The influence of surrounding rock temperature and initial temperature on total thermal accumulation capacity is more significant and it is approximately 2 times of the influence of slurry proportions under the conditions of this study. It is clear that the rise of surrounding rock temperature and the decrease of initial temperature can improve the thermal accumulation capacity more effectively. Moreover, the heat conduction accounts for a considerable proportion in the process of thermal accumulation, the average heat conduction capacity is approximately 25 times of the heat convection capacity. This study can provide the theoretical basis and application reference for the optimization of thermal accumulation process of CTB in the exploitation of geothermal resources.展开更多
Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and ...Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and composition of rare-earth tailings were investigated. The results show that roast conditions with the temperature of 650℃, carbon to oxygen ratio of 3.85, and holding time of 2.5 h are in favor of reduction of Fe_2O_3 to Fe_3O_4 when the roasted rare-earth tailings is cooled along with furnace. Under these roast conditions, magnetic susceptibility of rare-earth tailings is 2.36 that is very close to theoretical value（2.33）. However, magnetic separation results of iron in rare-earth tailings cooled along with furnace are not satisfactory. Through comparing magnetic separation results of iron in rare-earth tailings cooled by different ways, it is found that water cooling is more favored of magnetic separation of iron in the roasted rare-earth tailings than furnace cooling and air cooling. Grade and recovery of iron in concentrate from rare-earth tailings cooled by water are 45.00%-49.00% and 65.00%-77.50%, respectively.展开更多
A new technique of combining accretion by cyclone separator and scattertube for tailings dams was developed according to laboratory experiment, model experiment and spot experiment technology. Three tailings dams were...A new technique of combining accretion by cyclone separator and scattertube for tailings dams was developed according to laboratory experiment, model experiment and spot experiment technology. Three tailings dams were successfully constructed by the new technique. The results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailings dams prove that the new technique improves structure and stability of the dams and working conditions compared with the traditional technique. The thin layers of fine-grained soils are greatly reduced, fine tailings sand is solid to make the dam stable and seepage conditions are well improved; the immersing line of the dam descends. In addition, the stability and liquefaction resistance of tailings dams are strengthened remarkably. The interior stress is compressive stress, stress level of every element is less than 1.0 and safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailings dams is greater than 1.5 according to the analysis of seismic response by finite element method.展开更多
In this study,ceramics was prepared by slip casting(no pressure was used during shaping step)and atmospheric pressure sintering with low-melting point glass(LPG)powder as the binding material to facilitate the transfo...In this study,ceramics was prepared by slip casting(no pressure was used during shaping step)and atmospheric pressure sintering with low-melting point glass(LPG)powder as the binding material to facilitate the transformation of spodumene flotation tailings(SFTs)into ceramics at lower temperatures.The influence of sintering temperature and mass ratio of LPG on the mechanical properties(flexural strength and compressive strength)of ceramic materials was studied by orthogonal test.The results showed that when the mass ratio of LPG powder was higher than or equal to 20 wt%and the sintering temperature was higher than or equal to 550℃,mutual adhesion between the sample particles was realised and consequently the ceramic materials could be prepared with good mechanical properties(the maximum flexural strength=19.55 MPa,the maximum compressive strength=42.25 MPa,average porosity=24.52%,average apparent density=1.66 g/cm^(3),and average water absorption=14.79%).The sintered ceramics were characterized by XRF,XRD,optical microscopy analysis,SEM,TGA-DSC and FT-IR.The formation of liquid phase at high temperature may lead to the mutual bonding between particles,which might be the main reason for the improvement of mechanical properties of ceramic materials.Overall,SFTs were successfully sintered at low temperature to prepare ceramic materials with good mechanical properties,which are crucial for energy conservation and environmental preservation.展开更多
The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, ...The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the tailings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most tailings. The large proportion of heavy metals exists in the form of residual fraction in most tailings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the tailings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387.00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.展开更多
The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a funct...The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage,solution pH value and shaking time were determined by batch experiments.The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation tailings as adsorbent.The methods,such as zeta potentials,specific surface area measurements and the analysis of adsorption kinetics,were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings.The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb2+ ions.The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions.These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings.Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model,and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation tailings.展开更多
基金Project(5206800)supported by the National Natural Science Foundation of ChinaProject(2024JJA160096)supported by the Natural Science Foundation of Guangxi Province,China。
文摘Bauxite tailing(BT)slurry has been generated and accumulated in large quantities,posing a threat to the green and sustainable development of the alumina industry.The regression equation between the actual water content and mud water separation rate was established to achieve efficient resource utilization,and the feasibility of foam lightweight soil(FLS)prepared from BT was investigated.The effects of industrial waste residues(fly ash and slag powder)on the properties of FLS were studied.Meanwhile,the micro-mechanisms were revealed by XRD,SEM-EDS,and TG-DSC.The results revealed that fly ash reduced the workability and compressive strength of FLS.Slag powder can significantly enhance the compressive strength of FLS,which increased by 18.60%-23.26%,17.07%-58.54% and 12.12%-52.12%,respectively.Besides,slag powder can improve the long-term water stability performance and enhance carbonation resistance.XRD and thermal analyses showed that adding fly ash decreased the hydration degree of FLS,leading to a decrease in the hydration products.Slag powder improved the pore structure and compacted the skeleton structure of FLS.This study would provide an effective way to realize the resource utilization of BT,fly ash,and slag powder,with certain socio-economic and environmental benefits.
基金Project(2024JJ2074) supported by the Natural Science Foundation of Hunan Province,ChinaProject(22376221) supported by the National Natural Science Foundation of ChinaProject(2023QNRC001) supported by the Young Elite Scientists Sponsorship Program by CAST,China。
文摘Driven by rapid technological advancements and economic growth,mineral extraction and metal refining have increased dramatically,generating huge volumes of tailings and mine waste(TMWs).Investigating the morphological fractions of heavy metals and metalloids(HMMs)in TMWs is key to evaluating their leaching potential into the environment;however,traditional experiments are time-consuming and labor-intensive.In this study,10 machine learning(ML)algorithms were used and compared for rapidly predicting the morphological fractions of HMMs in TMWs.A dataset comprising 2376 data points was used,with mineral composition,elemental properties,and total concentration used as inputs and concentration of morphological fraction used as output.After grid search optimization,the extra tree model performed the best,achieving coefficient of determination(R2)of 0.946 and 0.942 on the validation and test sets,respectively.Electronegativity was found to have the greatest impact on the morphological fraction.The models’performance was enhanced by applying an ensemble method to the top three optimal ML models,including gradient boosting decision tree,extra trees and categorical boosting.Overall,the proposed framework can accurately predict the concentrations of different morphological fractions of HMMs in TMWs.This approach can minimize detection time,aid in the safe management and recovery of TMWs.
基金Projects(52274108,U2341265)supported by the National Natural Science Foundation of ChinaProject(2022YFC2904103)supported by the National Key Research and Development Program of China。
文摘Utilizing mine solid waste as a partial cement substitute(CS)to develop new cementitious materials is a significant technological innovation that will decrease the expenses associated with filling mining.To realize the resource utilization of magnesium slag(MS)and blast furnace slag(BFS),the effects of different contents of MS and BFS as partial CSs on the deformation and energy characteristics of cemented tailings backfill on different curing ages(3,7,and 28 d)were discussed.Meanwhile,the destabilization failure energy criterion of the backfill was established from the direction of energy change.The results show that the strength of all backfills increased with increasing curing age,and the strengths of the backfills exceeded 1.342 MPa on day 28.The backfill with 50%BFS+50%cement has the best performance in mechanical properties(the maximum strength can reach 6.129 MPa)and is the best choice among these CS combinations.The trend in peak strain and elastic modulus of the backfill with increasing curing age may vary depending on the CS combination.The energy index at peak stress of the backfill with BFS as a partial CS was significantly higher than that of the backfill under other CS combinations.In contrast,the enhancement of the energy index when MS was used as a partial CS was not as significant as BFS.Sharp changes in the energy consumption ratio after continuous smooth changes can be used as a criterion for destabilization and failure of the backfill.The research results can provide guidance for the application of MS and BFS as partial CSs in mine filling.
文摘The distribution of tailings lenticles reflects the sediment state of tailing dam, and has a great influence on the stability of the dam. In order to disclose the distribution law of tailings lenticles in theory, 12 geological cross-sections, including 7 cross-sections of tailings dam constructed by the upstream method and 5 cross-sections by the middle line method, were analyzed with box dimension method. The results show that the distribution of tailings lenticles has better fractal character with box dimension from 1.290 7 to 1.513 6. The box dimension of the tailings dam constructed by upstream method is nearly 1.50 and that by middle line method is 1.30. Thereby the values of lenticles dimension have obvious relation to the method of constructing dam, and reflect the sediment state of tailings dam with the rule that smaller value means better state.
文摘The initial shear stress and plastic cohesion ( η ) are the most important parameters reflecting the rheological properties of the paste slurry. The rheological parameters as well as the quantitative relationship among the consumption of different fill materials were obtained through the experiment and research on these parameters. They can be used to predict the scope of the values of τ and η in production for a given ratio, which can reduce the conveying resistance of fill slurry along the pipelines and avoid the blockage of the pipelines. It is found that the rheological model of the total tailing slurry belongs to the Bingham type, which has a feature of strong internal structure and large initial shear stress. The calculation formula for the resistance loss of pipelines conforms nicely to the field test and the actual production in Jinchuan Nickel Mine.
基金Project(2006BAB02A03) supported by National Key Technology Research and Development ProgramProject(2006BA02B05) supported by Key Programs for Science and Technology Development of China during the 11th Five Year
文摘A new technology characterized by rapidly non-mechanical settlement of unclassified tailings was developed based on a large number of tests, and dynamic settlement and continual slurry preparation without hardening in vertical sand silo were eventually realized by the addition of an effective flocculating agent (NPA). The results show that the sedimentation velocity of interface between unclassified tailings and water after the addition of NPA increases by 10-20 times, the sedimentation mass fraction of unclassified tailings at the bottom of vertical sand silo is up to 64%, the solid particle content of waste water meets the national standard, and the side influences of NPA can be removed by the addition of fly ash. The industrial test result shows that the system, the addition manner and the equipments are rational, and the vertical sand silo is used efficiently. This developed system is simple with large throughput, and the processing cost is 2.2 yuan(RMB)/m3, only 10%-20% of that by mechanical settlement.
基金Project(51722401)supported by the National Science Foundation for Excellent Young Scholars of ChinaProject(51334001)supported by the Key Program of National Natural Science Foundation of ChinaProject(FRF-TP-18-003C1)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Adding polypropylene(PP)fibers and coarse aggregates has become a popular way to enhance the strength and stability of the cemented tailings backfilling(CTB)body.It is essential to explore the influence of tailings-aggregate ratio and fiber content on the mechanical properties of CTB samples.The comprehensive tests of the unconfined compressive strength(UCS),slump and microstructure were designed,and the regression models were established to characterize the effect of the strength,ductility and fluidity.The results indicate that the tailings-aggregate ratio of 5:5 and PP fiber content of 0.5 kg/m^(3) are the optimum point considering the UCS,cracking strain,peak strain and post-peak ductility.The tailings-aggregate ratio is consistent with the unary quadratic to the UCS and a linear model with a negative slope to the slump.Microstructural analysis indicates that PP fiber tends to bridge the cracks and rod-mill sand to serve as the skeleton of the paste matrix,which can enhance the compactness and improve the ductility of the CTB.The results presented here are of great significance to the understanding and application of coarse aggregates and fibers to improve the mechanical properties of CTB.
基金Project(SKLCRSM13KFB05)supported by State Key Laboratory for Coal Resources and Safe Mining(China University of Mining&Technology)
文摘Cemented tailings backfill(CTB) is made by mixing cement, tailings and water together, thus cement hydration and water seepage flow are the two crucial factors affecting the quality of CTB. Cement hydration process can release significant amount of heat to raise the temperature of CTB and in turn increase the rate of cement hydration. Meanwhile, the progress of cement hydration consumes water and produces hydration products to change the pore structures within CTB, which further influences the hydraulic behavior of CTB. In order to understand the hydraulic behavior of CTB, a numerical model was developed by coupling the hydraulic,thermal and hydration equations. This model was then implemented into COMSOL Multiphysics to simulate the evolutions of temperature and water seepage flow within CTB versus curing time. The predicted outcomes were compared with correspondent experimental results, proving the validity and availability of this model. By taking advantage of the validated model, effects of various initial CTB and curing temperatures, cement content, and CTB's geometric shapes on the hydraulic behavior of CTB were demonstrated numerically. The presented conclusions can contribute to preparing more environmentally friendly CTB structures.
基金Projects(2018YFC0808403,2018YFE0123000)supported by the National Key Technologies Research&Development Program of ChinaProject(800015Z1185)supported by the Yueqi Young Scholar Project,ChinaProject(2020YJSNY04)supported by the Fundamental Research Funds for the Central Universities,China。
文摘It is of great significance for safety reason to obtain the triaxial compressive properties of cemented tailings backfill(CTB).The influence of cement content,curing age and confining pressure on strength and deformation properties of CTB was examined and discussed.Results indicate that the triaxial compressive and deformation behavior of CTB is strongly affected by the cement content,curing age and confining pressure.The increase in cement content,curing age and confining pressure leads to a change in stress−strain behavior and an increase in the axial strain at failure and post-peak strength loss.The cohesion of CTB rises as the curing age and cement content increase.However,the enhancement in internal friction angle is trivial and negligible.It should be noted that the failure pattern of CTB samples in triaxial compression is mainly along a shear plane,the confining pressure restrains the lateral expansion and the bulging failure pattern is dominantly detected in CTB samples as curing age length and cement content increase.The results will help to better understand the triaxial mechanical and deformation behavior of CTB.
基金Project(51172287)supported by the National Natural Science Foundation of ChinaProject(2012-2013)supported by the Laboratory Research Fund of the State Key Laboratory of Powder Metallurgy,China
文摘In order to develop the applications of ore tailings, the glass ceramics were prepared by using a conventional melting-quenching-sintering process. The phase component, microstructures, magnetic properties and thermal conductivities of the prepared glass ceramics were investigated by using X-ray diffractometer, scanning electron microscopy, vibrating sample magnetometer and thermophysical properties tester, respectively. The results show that orthorhombic olivine-type phase and triclinic sunstone-type phase formed when the glass was annealed at 700 oC, the concentration of olivine-type and sunstone-type phases decreased, the spinel-type cubic phase occurred and the amount increased when the annealing temperatures increased. The magnetic properties from the cubic spinel ferrites were detected in the glass ceramics, and the related saturation magnetization increased with the annealing temperature increasing. The porous glass ceramics with magnetic property showed much lower thermal conductivity, compared with the non-magnetic porous glass-ceramic and the dense glass-ceramics.
基金Project(2016zzts109)supported by the Innovation Driven Plan of Central South University,ChinaProject(2015CX005)supported by the Innovation driven Program of National Basic Research Program of ChinaProject(B14034)supported by the Program of Introdution Talents of Discipline to Universities,China(111 Project)
文摘Flotation tailings were successfully flocculated in the presence of cationic polyacrylamide and silica gel.The effects of various parameters such as polymer weight,charge density,and pH on the rate of flocculation were also investigated in the current study.The flocculation mechanism of the flocculant on tailings was investigated using zeta potential and Fourier transform infrared(FTIR)measurements.The results obtained reveal that 1)sodium silicate gel,used as a binder for the consolidation of tailings form primary flocs,acts as an anchor and the adsorption of polymer flocculant on these anchors results in the formation of larger flocs and,consequently,enhanced settling rate;2)flocculation in the presence of silica gel and polymer has a faster settling rate than single-polymer flocculation owing to the mechanisms of charge neutralization and bridging as identified using zeta potential and FTIR measurements.A pilot level study was conducted to investigate the influence of processed water on the flotation of scheelite.The results show that the proposed tailing disposal method could improve scheelite recovery by 2%(approximately)and could reduce the daily operation costs of the plant by approximately 108.57 USD.
基金Project(11JJ2031)supported by the Key Project of Natural Fund of Hunan Province,ChinaProject(2009SK3029)supported by the Plan of Hunan Provincial Science and Technology Department,China
文摘The effect of sulfur addition/solids content(SA/SC)ratio on heavy metals(e.g.copper,zinc and lead)obtained from mine tailings by indigenous sulfur-oxidizing bacteria was studied,and the changes in the chemical forms of heavy metals after bioleaching were explored.The results show that the solubilization of metals is significantly influenced by SA/SC ratio,and SA/SC ratio of 2.50 is found to be the best for bacterial activity and metal solubilization among six SA/SC ratios tested(such as 1.00,1.33,1.50,1.67,2.00 and 2.50)under the chosen experimental conditions.The pH decreases fast and the maximum solubilizations of copper and zinc are respectively 81.76% and 84.35% while that of lead only reaches 40.36%.After bioleaching,the chemical forms of heavy metals have changed.The metals remained in mine tailings are mainly found in residual fractions,which is harmless to the surrounding environment.
基金Projects(03JJY3078, 04JJ40032) supported by the Natural Science Foundation of Hunan Province, China project(03A006) supported by Scientific Research Fund of Hunan Provincial Education Department, China
文摘Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diffusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam’s acceleration, seismic dynamic stress and pore water pressure were obtained. The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly. The interior stress is compressive stress, the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method. The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams’ stability during earthquake is secondary reason.
基金Project(202202AG050010)supported by the Yunnan Major Scientific and Technological Projects,ChinaProject(202103AA080007)supported by the Key R&D Project of Science and Technology Department of Yunnan Province,ChinaProject(NECP2023-06)supported by the Open Project Fund of National Engineering and Technology Research Center for Development&Utilization of Phosphorous Resources,China。
文摘The long-term storage of phosphate tailings will occupy a large amount of land,pollute soil and groundwater,thus,it is crucial to achieve the harmless disposal of phosphate tailings.In this study,high-performance geopolymers with compressive strength of 38.8 MPa were prepared by using phosphate tailings as the main raw material,fly ash as the active silicon-aluminum material,and water glass as the alkaline activator.The solid content of phosphate tailings and fly ash was 60%and 40%,respectively,and the water-cement ratio was 0.22.The results of XRD,FTIR,SEM-EDS and XPS show that the reactivity of phosphate tailings with alkaline activator is weak,and the silicon-aluminum material can react with alkaline activator to form zeolite and gel,and encapsulate/cover the phosphate tailings to form a dense phosphate tailings-based geopolymer.During the formation of geopolymers,part of the aluminum-oxygen tetrahedron replaced the silicon-oxygen tetrahedron,causing the polycondensation reaction between geopolymers and increasing the strength of geopolymers.The leaching toxicity test results show that the geopolymer has a good solid sealing effect on heavy metal ions.The preparation of geopolymer from phosphate tailings is an important way to alleviate the storage pressure and realize the resource utilization of phosphate tailings.
基金Projects(51974225,51674188,51874229,51904224,51904225,51704229)supported by the National Natural Science Foundation of ChinaProject(2018KJXX-083)supported by the Shaanxi Innovative Talents Cultivate Program-New-Star Plan of Science and Technology,China+2 种基金Projects(2018JM5161,2018JQ5183,2015JM-074)supported by the Natural Science Basic Research Plan of Shaanxi Province,ChinaProject(19JK0543)supported by the Scientific Research Program funded by Education Department of Shaanxi Province,ChinaProject(2018YQ201)supported by the Outstanding Youth Science Fund of Xi’an University of Science and Technology,China。
文摘Based on the collaborative exploitation of deep mineral resources and geothermal resources, the thermal accumulation process of cemented tailings backfill(CTB) was studied by numerical simulation. The effects of thermal accumulation time, slurry proportions and temperature conditions on the thermal accumulation of backfill are analyzed, the influence of the heat conduction between backfill and surrounding rock, the heat convection between backfill and airflow on thermal accumulation were compared simultaneously. The results show that the total thermal accumulation capacity increases by approximately 85% within 10-90 d. The influence of surrounding rock temperature and initial temperature on total thermal accumulation capacity is more significant and it is approximately 2 times of the influence of slurry proportions under the conditions of this study. It is clear that the rise of surrounding rock temperature and the decrease of initial temperature can improve the thermal accumulation capacity more effectively. Moreover, the heat conduction accounts for a considerable proportion in the process of thermal accumulation, the average heat conduction capacity is approximately 25 times of the heat convection capacity. This study can provide the theoretical basis and application reference for the optimization of thermal accumulation process of CTB in the exploitation of geothermal resources.
基金Project(2012CBA01205)supported by National Basic Research Program of ChinaProjects(50934004,51274061)supported by the National Natural Science Foundation of ChinaProject(N110502002)supported by the Fundamental Research Funds for the Central Universities,China
文摘Magnetic separation of iron in rare-earth tailings was achieved by magnetizing roast process with coal as reductant. Effects of the temperature, carbon to oxygen ratio, and cooling type on magnetic susceptibility and composition of rare-earth tailings were investigated. The results show that roast conditions with the temperature of 650℃, carbon to oxygen ratio of 3.85, and holding time of 2.5 h are in favor of reduction of Fe_2O_3 to Fe_3O_4 when the roasted rare-earth tailings is cooled along with furnace. Under these roast conditions, magnetic susceptibility of rare-earth tailings is 2.36 that is very close to theoretical value（2.33）. However, magnetic separation results of iron in rare-earth tailings cooled along with furnace are not satisfactory. Through comparing magnetic separation results of iron in rare-earth tailings cooled by different ways, it is found that water cooling is more favored of magnetic separation of iron in the roasted rare-earth tailings than furnace cooling and air cooling. Grade and recovery of iron in concentrate from rare-earth tailings cooled by water are 45.00%-49.00% and 65.00%-77.50%, respectively.
文摘A new technique of combining accretion by cyclone separator and scattertube for tailings dams was developed according to laboratory experiment, model experiment and spot experiment technology. Three tailings dams were successfully constructed by the new technique. The results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailings dams prove that the new technique improves structure and stability of the dams and working conditions compared with the traditional technique. The thin layers of fine-grained soils are greatly reduced, fine tailings sand is solid to make the dam stable and seepage conditions are well improved; the immersing line of the dam descends. In addition, the stability and liquefaction resistance of tailings dams are strengthened remarkably. The interior stress is compressive stress, stress level of every element is less than 1.0 and safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailings dams is greater than 1.5 according to the analysis of seismic response by finite element method.
基金Projects(51674207,51922091)supported by the National Natural Science Foundation of ChinaProject(2018QNRC001)supported by the Young Elite Scientists Sponsorship Program by CAST,ChinaProjects(2019YFS0453,2018JY0148)supported by the Sichuan Science and Technology Program,China。
文摘In this study,ceramics was prepared by slip casting(no pressure was used during shaping step)and atmospheric pressure sintering with low-melting point glass(LPG)powder as the binding material to facilitate the transformation of spodumene flotation tailings(SFTs)into ceramics at lower temperatures.The influence of sintering temperature and mass ratio of LPG on the mechanical properties(flexural strength and compressive strength)of ceramic materials was studied by orthogonal test.The results showed that when the mass ratio of LPG powder was higher than or equal to 20 wt%and the sintering temperature was higher than or equal to 550℃,mutual adhesion between the sample particles was realised and consequently the ceramic materials could be prepared with good mechanical properties(the maximum flexural strength=19.55 MPa,the maximum compressive strength=42.25 MPa,average porosity=24.52%,average apparent density=1.66 g/cm^(3),and average water absorption=14.79%).The sintered ceramics were characterized by XRF,XRD,optical microscopy analysis,SEM,TGA-DSC and FT-IR.The formation of liquid phase at high temperature may lead to the mutual bonding between particles,which might be the main reason for the improvement of mechanical properties of ceramic materials.Overall,SFTs were successfully sintered at low temperature to prepare ceramic materials with good mechanical properties,which are crucial for energy conservation and environmental preservation.
基金Project (2001AA644020) supported by the National"863"High Technology Research and Development Program of China
文摘The tailing soils were from 10 mining areas in Hunan Province. To predict the potential impact of tailings on nearby environments, the characteristics such as the pH value, loss on ignition, cation exchange capacity, and the concentration and speciation of heavy metals in the tailings were investigated. Based on these characteristics, the pollution index and danger index were calculated so as to evaluate the priorities of remediation. The results show that the concentrations of Pb, Cd, Cu and Zn exceed the tolerable levels of the phytotoxicity in the most tailings. The large proportion of heavy metals exists in the form of residual fraction in most tailings, followed by sulfides/organic and Fe/Mn oxide fractions, and a little in the exchangeable and carbonate fraction. The calculated pollution indices for the tailing samples range from 1.41 to 83.42, which indicates that all the tailings contain heavy metals at a level that causes toxicity to the ecosystem. The danger indices for the tailing samples range from 0.06 to 387.00. The highest value of the danger indices is that of Yongzhou sample, reaching 387.00; the lowest one is that of Xikuangshan sample, only 0.06. Considering the results of pollution index and danger index in combination, the priority of remediation is determined to be Yongzhou, Baoshan, Xiangtan and Lengshuijiang.
基金Project(2005CB623701) supported by the Major State Basic Research Development Program of China
文摘The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings.The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage,solution pH value and shaking time were determined by batch experiments.The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation tailings as adsorbent.The methods,such as zeta potentials,specific surface area measurements and the analysis of adsorption kinetics,were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings.The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb2+ ions.The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions.These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings.Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model,and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation tailings.
