Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated u...Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.展开更多
The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment ...The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.展开更多
Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size dis...Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size distribution of the pretreated limestone,the particle morphology,the activity of the calcined limestone and the fluidity of the liquid phase during sintering are all improved.When the substitution ratio of the pretreated limestone for burnt lime is kept at 50%,the granulation performance and sinter indices in sinter pot tests are both better compared with that of the base case.Much denser interleaved texture in product sinter is formed with the reduction of sinter porosity and improvement of silico-ferrite of calcium and alumina amount.When the particle size of the pretreated limestone is maintained within the optimal range of 0–2 mm,the tumble index,yield and productivity increase by 7.2%,2.6%and 11.2%,respectively,while the solid fuel rate decreases by 8.7%.In the corresponding sinter industry production,the tumble index and output of the product sinter are comparable to those of the base case,while the coke dosage is reduced by 9.0%.Reduction index and reduction degradation index(RDI_(+3.15))are both higher than 74%.The cost of raw materials in sintering process can be greatly reduced.展开更多
The effects of oxidation-reduction treatment and mechanical activation on the hydrochloric acid leaching performance of Panxi ilmenite concentration were investigated.The results show that both of oxidation-reduction ...The effects of oxidation-reduction treatment and mechanical activation on the hydrochloric acid leaching performance of Panxi ilmenite concentration were investigated.The results show that both of oxidation-reduction treatment and mechanical activation significantly accelerate the extraction of Fe,Ca and Mg from Panxi ilmenite concentration;however,the CaO and MgO contents of the calcined residues obtained from oxidized-reduced ilmenite concentration are higher than the standard values required by chlorination process.The Ca and Mg in oxidized-reduced ilmenite concentration can be leached much faster after mechanical activation,yielding a synthetic rutile which meets the requirements of chlorination process containing 90.50% TiO2 and 1.37% total iron as well as combined CaO and MgO of 1.00%.The optimum oxidation and reduction conditions are as follows：oxidization at 900 ℃ in the presence of oxygen for 15 min and reduction at 750 ℃ by hydrogen for 30 min.展开更多
Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The ...Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation （MA） induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H2SO4 concentration were found to be 0.34, 0.30, and 0.29, respectively.展开更多
In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures ...In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures and heat behaviors of activated samples were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） analysis,and simultaneous thermal analysis（STA）.It is found that the sulfide minerals after mechanical activation show many changes with increased specific surface areas,aggregation phenomenon,decreased diffraction peak intensity,broadened diffraction peak,declined initial temperatures of heat release and self-ignition points.A new theory for explaining the spontaneous combustion of sulfide minerals is put forward：the chemical reaction activity of sulfide minerals is heightened by all kinds of mechanical forces during the mining,and the spontaneous combustion takes place finally under proper environment.展开更多
The use of mechanical activation to enhance gold recovery from a CuPbZn complex sulfide concentrate was investigated. The effects of milling time, ball size, sample to ball ratio and milling speed on thiosulfate leach...The use of mechanical activation to enhance gold recovery from a CuPbZn complex sulfide concentrate was investigated. The effects of milling time, ball size, sample to ball ratio and milling speed on thiosulfate leaching were studied. Under optimum conditions of milling time 1 h, ball size 20 mm, sample to ball ratio 1/15 and mill speed 600 r/min, nearly 78% of sample is amorphized, particle size decreases from d100=30 μm to d100=8 μm, specific surface area increases from 1.3 m2/g to 4.6 m2/g and gold recovery enhances from 17.4 % in non-activated sample to 73.26 %.展开更多
On the basis of analyzing coal gangue＇s chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the c...On the basis of analyzing coal gangue＇s chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.展开更多
The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. There- fore, this study optimized an innovative process, which does not require a high-temperatu...The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. There- fore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from le- pidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and re- sponse-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphi- zation and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.展开更多
Mechanical activation was used to improve the extraction of chromium in molten NaOH.It is observed that the extraction ratio reaches 97% after leaching for 200 min when chromite ore is mechanically activated for 10 mi...Mechanical activation was used to improve the extraction of chromium in molten NaOH.It is observed that the extraction ratio reaches 97% after leaching for 200 min when chromite ore is mechanically activated for 10 min,but only 34% if not activated.Mechanical activation can decrease the particle size,increase the surface area,and enhance the lattice distortion.Further,the mechanisms for mechanical activation were exposed.The results show that the mechanical activation mainly focuses on chromite ore particle size decrease and the lattice distortion.The formation of aggregation weakens the strengthening effect of mechanical activation for releasing high surface energy.展开更多
Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malach...Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malachite reached the maximum and the particle size reached the minimum of 0.7–100 μm. Agglomeration occurred between mineral particles when the rotational speed was increased to 580 r/min in DPG.However, no agglomeration was observed among particles with sizes 0.4–3 μm in WIG. X-ray diffraction analysis showed that, at a 580 r/min rotational speed in DPG, the amorphization degree of malachite was 53.12%, whereas that in WIG was 71.40%, indicating that MA led to amorphization and distortion of crystal structures. In addition, in the Fourier transform infrared(FT-IR) spectra of activated malachite, the bands associated with –OH, CO_3^(2-)and metal lattice vibrations of Cu–O and Cu–OH were weakened, and a new H–O–H bending mode and peaks of gaseous CO_2 appeared, indicating that MA decreased the band energy, enhanced dihydroxylation, and increased the chemical reactivity of the malachite.Furthermore, the leaching behavior of copper ore was greatly improved by MA.展开更多
The effect of mechanical activation （MA） on the kinetics of terbium （Tb） leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy...The effect of mechanical activation （MA） on the kinetics of terbium （Tb） leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy and reaction order, were determined using the shrinking-core model and the Arrhenius equation. Results obtained from experiments with different concentrations of HC1 and under different leaching temperatures were used for the determinations. The impacts of factors such as rotational speed, HC1 concen- tration and leaching temperature on the leaching rate of Tb were also discussed. The results showed that MA could dramatically increase the leaching rate of Tb from waste phosphors, and the apparent reaction rate （kap） of leaching was accelerated as well. For inactivated waste phosphors, the apparent activation energy （Eap） was 52.82±3.95 kJ/mol, indicating that the rate-controlling step of the leaching process was the chemical reaction. The Eap dropped to 25.96 ±3.90 kJ/mol and 10.96±2.79 k J/tool when the waste phosphors were mechanically activated at rotational speeds of 400 and 600 r/min, respectively; the leaching process transformed to a hybrid （chemical-reaction and diffusion） control process, and even a reagent-diffusion （through the product layer） control process. The apparent reaction order for Tb leaching from 400 r/min-activated waste phosphors was 2.49±0.11, and it decreased to 1. 16±0.17 when the rotational speed of 600 r/min was used. Kinetics results indicated that MA could make Tb leaching occur spontaneously, and thc activation intensity of waste phosphors was strengthened with higher rotational speed.展开更多
Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic ...Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic performance.Tetracycline degradation was evaluated in the presence of hydrogen peroxide and mechanically activated chalcopyrite.Tetracycline degradation at 100 min is 55.52%(Chp10), 68.97%(Chp30), 77.79%(Chp60), and 86.43%(Chp120),respectively, and the rate constant of pseudo-first-order kinetics is 0.0079, 0.0109, 0.0137 and 0.0192 min^(-1), respectively.Chalcopyrite samples were examined by multiple characterizations. Mechanical activation of natural chalcopyrite induces the decline of particle size and slight increase of surface area, smaller grain size, lattice strain, and partial sulfur oxidation. The relationship between catalytic activity and property change manifests that the improved catalytic ability is mainly ascribed to the increase of surface area and surface oxidation induced by mechanical activation. This work provides novel insights into the improvement of catalytic performance of natural minerals by mechanical activation.展开更多
The effects of mechanical activation on particle size distribution,crystalline phase,morphology,and mechanical energy storage of nickel slag were studied.Then,the direct reduction experiments of mechanically activated...The effects of mechanical activation on particle size distribution,crystalline phase,morphology,and mechanical energy storage of nickel slag were studied.Then,the direct reduction experiments of mechanically activated nickel slag mixed with reducing agent graphite powder were performed under conditions of 873-1273 K and reduction for 30-70 min.The results show that after 12 h of activation,90%of the nickel slag has a particle diameter less than 1.05 pm,and the total energy storage is 1790.4 kJ mol^(-1).With the extension of the mechanical activation duration,the intensity of the dift'raction peaks of the main crystalline phases Fe_(2)SiO_(4) and Mg2SiO4 in the nickel slag decreases.Mechanical activation is also an effective means to enhance the reduction of nickel slag.With the extension of the activation time,the reduction effect of the nickel slag and metallization degree increase.After 12 h of mechanical activation,the nickel slag was reduced at 1273 K for 70 min,and the metallization degree of the reduced product could reach 83.12%.展开更多
After milling in a high energy ball miller for various times, the synthesis reaction process of the Al Ti C powder mixture were investigated by difference thermal analysis (DTA) and X ray diffractometry (XRD). Accordi...After milling in a high energy ball miller for various times, the synthesis reaction process of the Al Ti C powder mixture were investigated by difference thermal analysis (DTA) and X ray diffractometry (XRD). According to the patterns of reaction peaks on the DTA curves, the activation energy of each reaction was calculated. The experimental results of DTA show that the synthesis reaction of Al Ti C powder mixture can be enhanced after high energy milling. The longer the milling time, the lower the reaction temperature. The synthesis reaction of TiC is transformed from Ti+C→TiC to Al 3Ti+C→TiC+3Al with long period milling. Meanwhile, the activation energy of the reaction reduces with increasing milling time. The effect of milling time on reduced activation energy for low temperature region is more significant than that for high temperature region.展开更多
To explore the effects of mechanical activation methods(ball mill, planetary mill and rod mill) on the oxidation and the spontaneous combustion of pyrite, the kinetic curves of non-activated pyrite and mechanically ac...To explore the effects of mechanical activation methods(ball mill, planetary mill and rod mill) on the oxidation and the spontaneous combustion of pyrite, the kinetic curves of non-activated pyrite and mechanically activated pyrite were created by simultaneous thermal analysis. The structural characteristics and changes of mechanically activated pyrite were investigated by X-ray diffraction and SEM, and the relationship between the mean diameter and the grinding time was obtained by using a laser particle size analyzer. The kinetic model of pyrite and the kinetic parameters were deduced using Bagchi method. The relationship between the kinetic parameters indicates that, pyrite activated by ball milling shows the best thermal stability at the same diameter. By comparing and analyzing the X-ray diffraction patterns, results show that different mechanical activation ways played different roles in structural changes of pyrite.展开更多
The effects of mechanical activation in a planetary mill on the structural changes and microstructural characteristics of the components of ferruginous quartzite beneficiation railings generated by wet magnetic separa...The effects of mechanical activation in a planetary mill on the structural changes and microstructural characteristics of the components of ferruginous quartzite beneficiation railings generated by wet magnetic separation process were studied using X-ray and laser diffraction methods. The results revealed the relationship between variations in the mean particle size of activated powders and the milling time. The crystallite size, microstrain, lattice parameters and unit cell volumes were determined for different milling times in powder samples of quartz, hematite, dolomite, and magnetite from the beneficiation tailings. The main trends in the variation of the crystallite size of quartz, hematite, dolomite, and magnetite as a function mean particle size of powder samples were revealed. Changes in the particle shape as a function of the activation time was also investigated.展开更多
A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni（OH）2-NiCO3-4H2O was synthesized by chemical precipitation. The precursor was milled...A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni（OH）2-NiCO3-4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio （BPR）, and nickel chlo-ride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption （λmax）. The effects of these pa-rameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a mill-ing time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio （NPR） of 6/1. In these conditions,λmax was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.展开更多
Spontaneously polarized crystals with intrinsic electric dipole moment have attracted immense interest as excellent functional materials for extensive applications.It is of great significance to engineer sustainable s...Spontaneously polarized crystals with intrinsic electric dipole moment have attracted immense interest as excellent functional materials for extensive applications.It is of great significance to engineer sustainable spontaneously polarized materials with fascinating characteristics and performance for activating air and water.Herein,a novel strategy based on the synergy of mechanical activation(MA)and biomimetic mineralization(BM)was created to construct spontaneously polarized ceramic.MA induced the structural damage of clay and promoted the dissolution of ions and the release of free proteins,contributing to the formation of silicate precursor in BM process.After high temperature firing,the silicate precursor in clay was converted to form KCa_(3)AlCa_(3)Si_(4)O_(16)(hexagonal crystal system,L^(6)symmetry type,and P63 space group)in the resulting spontaneously polarized ceramic.The non-centrosymmetric structure of KCa_(3)AlCa_(3)Si4O_(16)and the high intrinsic electric dipole moments contributed by K(1)polyhedrons resulted in high spontaneous polarization(0.2322μC/cm^(2))and far-infrared emissivity(0.951)of spontaneously polarized ceramic.In air,spontaneously polarized ceramic can activate H_(2)O and O_(2)molecules to form negative air ions owing to surface electric field.In water,spontaneously polarized ceramic can disaggregate large water clusters to form small water clusters ascribed to surface electric field and far-infrared emission;water pH can be regulated from weak acidity to approximate neutrality via the capture of electrons by H+ions to produce releasable hydrogen gas.This work provides great promise for rational design and synthesis of spontaneously polarized materials for functional applications.展开更多
Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The c...Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The crystalline of the activation derived perovskite BPO phase was further established when the activated mixture was subjected to calcination at 650 ℃. The perovskite phase was sintered to a density of 98% of theoretical value at 980 ℃ for 2 h. The sintered BPO with 0.1% Nd doped exhibits a resistivity of 2×10 -4 Ω·cm and an excellent PTC effect at Curie temperature of 750 ℃ .展开更多
基金Project(GZC20233199) supported by the Postdoctoral Fellowship Program of CPSF,ChinaProject(2022YFC2105300) supported by the National Key Research and Development Program of China。
文摘Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.
基金financially supported by the General Program of National Natural Science Foundation of China(No.52174330)Hunan Provincial Innovation Foundation for Postgraduate(No.QL20220069)Postgraduate Innovative Project of Central South University(No.1053320214756).
文摘The utilization of ironsand for preparing oxidized pellets poses challenges,including slow oxidation and low consolidation strength.The effects and function mechanisms of high-pressure grinding roll(HPGR)pretreatment on the oxidation and consolidation of ironsand pellets were investigated,and the energy utilization efficiency of HPGR with different roller pressure intensities was evaluated.The results indicate that HPGR pretreatment at 8 MPa improves the ironsand properties,with the specific surface area increasing by 740 cm^(2) g^(-1) and mechanical energy storage increasing by 2.5 kJ mol^(-1),which is conducive to oxidation and crystalline connection of particles.As roller pressure intensity increases to 16 MPa,more mechanical energy of HPGR is applied for crystal activation,with mechanical energy storage further rising by 18.1 kJ mol^(-1).The apparent activation energy for pellet oxidation initially decreases and then increases,reaching a minimum at 12 MPa.Simultaneously,the roasted pellets porosity decreases by 2.8%,while the compressive strength increases by 789 N.At higher roller pressure intensity,the densely connected structure between particles impedes gas diffusion within the pellets,diminishing the beneficial effects of HPGR on pellet oxidation.Moreover,excessive roller pressure intensity decreases the HPGR energy utilization efficiency.The optimal HPGR roller pressure intensity for ironsand is 12 MPa,at which the specific surface area increases by 790 cm^(2) g^(-1),mechanical energy storage increases by 10.6 kJ mol^(-1),the compressive strength of roasted pellets rises to 2816 N,and the appropriate preheating and roasting temperatures decrease by 250 and 125°C,respectively.
基金supported by Natural Science Foundation of Chongqing(No.CSTB2023NSCQ-BHX0166)Postdoctoral Science Foundation of China(No.2024T171095)Fundamental Research Funds for the Central Universities(No.2024CDJXY003).
文摘Limestone was pretreated via the mechanical activation method,and burnt lime was partially substituted by the pretreated limestone for better sinter indices and lower sintering costs.With the reduction in the size distribution of the pretreated limestone,the particle morphology,the activity of the calcined limestone and the fluidity of the liquid phase during sintering are all improved.When the substitution ratio of the pretreated limestone for burnt lime is kept at 50%,the granulation performance and sinter indices in sinter pot tests are both better compared with that of the base case.Much denser interleaved texture in product sinter is formed with the reduction of sinter porosity and improvement of silico-ferrite of calcium and alumina amount.When the particle size of the pretreated limestone is maintained within the optimal range of 0–2 mm,the tumble index,yield and productivity increase by 7.2%,2.6%and 11.2%,respectively,while the solid fuel rate decreases by 8.7%.In the corresponding sinter industry production,the tumble index and output of the product sinter are comparable to those of the base case,while the coke dosage is reduced by 9.0%.Reduction index and reduction degradation index(RDI_(+3.15))are both higher than 74%.The cost of raw materials in sintering process can be greatly reduced.
基金Project(2009FJ3082)supported by Research Project of Science and Technology in Hunan Province,ChinaProject(2007CB613606)supported by the National Basic Research Program of China
文摘The effects of oxidation-reduction treatment and mechanical activation on the hydrochloric acid leaching performance of Panxi ilmenite concentration were investigated.The results show that both of oxidation-reduction treatment and mechanical activation significantly accelerate the extraction of Fe,Ca and Mg from Panxi ilmenite concentration;however,the CaO and MgO contents of the calcined residues obtained from oxidized-reduced ilmenite concentration are higher than the standard values required by chlorination process.The Ca and Mg in oxidized-reduced ilmenite concentration can be leached much faster after mechanical activation,yielding a synthetic rutile which meets the requirements of chlorination process containing 90.50% TiO2 and 1.37% total iron as well as combined CaO and MgO of 1.00%.The optimum oxidation and reduction conditions are as follows：oxidization at 900 ℃ in the presence of oxygen for 15 min and reduction at 750 ℃ by hydrogen for 30 min.
基金Project(51064002)supported by the National Natural Science Foundation of ChinaProject(0728238)supported by the Natural Science Foundation of Guangxi Province,China
文摘Neutral leach residue of zinc calcine （NLRZC） was mechanically activated by a stirring ball mill. Subsequently, the changes in physicochemical properties and dissolution kinetics in sulphuric acid were studied. The crystalline structure, morphology, particle size and specific surface area of the non-activated and mechanically activated NLRZC were characterized by X-ray diffraction, scanning electron microscope, particle size analyzer and volumetric adsorption analyzer, respectively. The characterization results indicate that mechanical activation （MA） induced remarkable changes in the physicochemical properties of NLRZC. The leaching experiments show that MA significantly enhances the leaching reactivity of NLRZC using the zinc extraction as evaluating index. After NLRZC is mechanically activated for 30 min and 60 min, the activation energy decreases from 56.6 kJ/mol of non-activated NLRZC to 36.1 kJ/mol and 29.9 kJ/mol, respectively. The reaction orders of the non-activated, 30 and 60 min activated NLRZC dissolution with respect to H2SO4 concentration were found to be 0.34, 0.30, and 0.29, respectively.
基金Project(2012J05088) supported by the Natural Science Foundation of Fujian Province,ChinaProject(022409) supported by the School Talent Foundation of Fuzhou University,China
文摘In order to uncover the intrinsic reasons for spontaneous combustion of sulfide minerals,representative samples were collected from typical metal mines to carry out the mechanical activation experiment.The structures and heat behaviors of activated samples were characterized by scanning electron microscopy（SEM）,X-ray diffraction（XRD） analysis,and simultaneous thermal analysis（STA）.It is found that the sulfide minerals after mechanical activation show many changes with increased specific surface areas,aggregation phenomenon,decreased diffraction peak intensity,broadened diffraction peak,declined initial temperatures of heat release and self-ignition points.A new theory for explaining the spontaneous combustion of sulfide minerals is put forward：the chemical reaction activity of sulfide minerals is heightened by all kinds of mechanical forces during the mining,and the spontaneous combustion takes place finally under proper environment.
基金supported by Iran Mineral Processing Research Center (IMPRC)the IMPRC for the financial support of this work
文摘The use of mechanical activation to enhance gold recovery from a CuPbZn complex sulfide concentrate was investigated. The effects of milling time, ball size, sample to ball ratio and milling speed on thiosulfate leaching were studied. Under optimum conditions of milling time 1 h, ball size 20 mm, sample to ball ratio 1/15 and mill speed 600 r/min, nearly 78% of sample is amorphized, particle size decreases from d100=30 μm to d100=8 μm, specific surface area increases from 1.3 m2/g to 4.6 m2/g and gold recovery enhances from 17.4 % in non-activated sample to 73.26 %.
基金Funded by the Key Laboratory Foundation of Ecological-Environment Materials (Yancheng Institute of Technology) of Jiangsu Province (XKY2006020)the Natural Science Foundation of Jiangsu Provincial Education Depart-ment(07KJB430123)
文摘On the basis of analyzing coal gangue＇s chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.
基金the doctorate grant ref.9244/13-1 supplied by CAPES Foundation,Ministry of Education of Brazil
文摘The recovery of lithium from hard rock minerals has received increased attention given the high demand for this element. There- fore, this study optimized an innovative process, which does not require a high-temperature calcination step, for lithium extraction from le- pidolite. Mechanical activation and acid digestion were suggested as crucial process parameters, and experimental design and re- sponse-surface methodology were applied to model and optimize the proposed lithium extraction process. The promoting effect of amorphi- zation and the formation of lithium sulfate hydrate on lithium extraction yield were assessed. Several factor combinations led to extraction yields that exceeded 90%, indicating that the proposed process is an effective approach for lithium recovery.
基金Project(2009AA06XK1485430) supported by the National Hi-tech Research and Development Program of ChinaProject(2007CB613501) supported by the National Basic Research Program of China
文摘Mechanical activation was used to improve the extraction of chromium in molten NaOH.It is observed that the extraction ratio reaches 97% after leaching for 200 min when chromite ore is mechanically activated for 10 min,but only 34% if not activated.Mechanical activation can decrease the particle size,increase the surface area,and enhance the lattice distortion.Further,the mechanisms for mechanical activation were exposed.The results show that the mechanical activation mainly focuses on chromite ore particle size decrease and the lattice distortion.The formation of aggregation weakens the strengthening effect of mechanical activation for releasing high surface energy.
基金financially supported by the Special Funds for the National Natural Science Foundation of China(No.U1608254)the National Key R&D Program of China(No.2018YFC1902002)
文摘Mechanical activation(MA) of malachite was carried out by dry planetary grinding(DPG) and wet Isa grinding(WIG) methods. When the rotational speed was increased to 400 r/min in DPG, the specific surface area of malachite reached the maximum and the particle size reached the minimum of 0.7–100 μm. Agglomeration occurred between mineral particles when the rotational speed was increased to 580 r/min in DPG.However, no agglomeration was observed among particles with sizes 0.4–3 μm in WIG. X-ray diffraction analysis showed that, at a 580 r/min rotational speed in DPG, the amorphization degree of malachite was 53.12%, whereas that in WIG was 71.40%, indicating that MA led to amorphization and distortion of crystal structures. In addition, in the Fourier transform infrared(FT-IR) spectra of activated malachite, the bands associated with –OH, CO_3^(2-)and metal lattice vibrations of Cu–O and Cu–OH were weakened, and a new H–O–H bending mode and peaks of gaseous CO_2 appeared, indicating that MA decreased the band energy, enhanced dihydroxylation, and increased the chemical reactivity of the malachite.Furthermore, the leaching behavior of copper ore was greatly improved by MA.
基金Project supported by the National Key Technologies R&D Program(2014BAC03B04)
文摘The effect of mechanical activation （MA） on the kinetics of terbium （Tb） leaching from waste phosphors using hydrochloric acid was investigated. Leaching kinetics, such as apparent reaction rate, activation energy and reaction order, were determined using the shrinking-core model and the Arrhenius equation. Results obtained from experiments with different concentrations of HC1 and under different leaching temperatures were used for the determinations. The impacts of factors such as rotational speed, HC1 concen- tration and leaching temperature on the leaching rate of Tb were also discussed. The results showed that MA could dramatically increase the leaching rate of Tb from waste phosphors, and the apparent reaction rate （kap） of leaching was accelerated as well. For inactivated waste phosphors, the apparent activation energy （Eap） was 52.82±3.95 kJ/mol, indicating that the rate-controlling step of the leaching process was the chemical reaction. The Eap dropped to 25.96 ±3.90 kJ/mol and 10.96±2.79 k J/tool when the waste phosphors were mechanically activated at rotational speeds of 400 and 600 r/min, respectively; the leaching process transformed to a hybrid （chemical-reaction and diffusion） control process, and even a reagent-diffusion （through the product layer） control process. The apparent reaction order for Tb leaching from 400 r/min-activated waste phosphors was 2.49±0.11, and it decreased to 1. 16±0.17 when the rotational speed of 600 r/min was used. Kinetics results indicated that MA could make Tb leaching occur spontaneously, and thc activation intensity of waste phosphors was strengthened with higher rotational speed.
基金Project(2020YFC1908802) supported by the National Key Research and Development Project of China。
文摘Natural minerals receive growing attention as inexpensive, green, and efficient catalysts for degradation of organic pollutants. Mechanical activation of natural chalcopyrite was conducted for improving the catalytic performance.Tetracycline degradation was evaluated in the presence of hydrogen peroxide and mechanically activated chalcopyrite.Tetracycline degradation at 100 min is 55.52%(Chp10), 68.97%(Chp30), 77.79%(Chp60), and 86.43%(Chp120),respectively, and the rate constant of pseudo-first-order kinetics is 0.0079, 0.0109, 0.0137 and 0.0192 min^(-1), respectively.Chalcopyrite samples were examined by multiple characterizations. Mechanical activation of natural chalcopyrite induces the decline of particle size and slight increase of surface area, smaller grain size, lattice strain, and partial sulfur oxidation. The relationship between catalytic activity and property change manifests that the improved catalytic ability is mainly ascribed to the increase of surface area and surface oxidation induced by mechanical activation. This work provides novel insights into the improvement of catalytic performance of natural minerals by mechanical activation.
基金the National Natural Science Foundation of China(No.51774224)for the funding of this research.
文摘The effects of mechanical activation on particle size distribution,crystalline phase,morphology,and mechanical energy storage of nickel slag were studied.Then,the direct reduction experiments of mechanically activated nickel slag mixed with reducing agent graphite powder were performed under conditions of 873-1273 K and reduction for 30-70 min.The results show that after 12 h of activation,90%of the nickel slag has a particle diameter less than 1.05 pm,and the total energy storage is 1790.4 kJ mol^(-1).With the extension of the mechanical activation duration,the intensity of the dift'raction peaks of the main crystalline phases Fe_(2)SiO_(4) and Mg2SiO4 in the nickel slag decreases.Mechanical activation is also an effective means to enhance the reduction of nickel slag.With the extension of the activation time,the reduction effect of the nickel slag and metallization degree increase.After 12 h of mechanical activation,the nickel slag was reduced at 1273 K for 70 min,and the metallization degree of the reduced product could reach 83.12%.
文摘After milling in a high energy ball miller for various times, the synthesis reaction process of the Al Ti C powder mixture were investigated by difference thermal analysis (DTA) and X ray diffractometry (XRD). According to the patterns of reaction peaks on the DTA curves, the activation energy of each reaction was calculated. The experimental results of DTA show that the synthesis reaction of Al Ti C powder mixture can be enhanced after high energy milling. The longer the milling time, the lower the reaction temperature. The synthesis reaction of TiC is transformed from Ti+C→TiC to Al 3Ti+C→TiC+3Al with long period milling. Meanwhile, the activation energy of the reaction reduces with increasing milling time. The effect of milling time on reduced activation energy for low temperature region is more significant than that for high temperature region.
基金Funded by the National Natural Science Foundation of China(Nos.51174153 and 51374164)Hubei Natural Science Foundation(No.2014CFB879)
文摘To explore the effects of mechanical activation methods(ball mill, planetary mill and rod mill) on the oxidation and the spontaneous combustion of pyrite, the kinetic curves of non-activated pyrite and mechanically activated pyrite were created by simultaneous thermal analysis. The structural characteristics and changes of mechanically activated pyrite were investigated by X-ray diffraction and SEM, and the relationship between the mean diameter and the grinding time was obtained by using a laser particle size analyzer. The kinetic model of pyrite and the kinetic parameters were deduced using Bagchi method. The relationship between the kinetic parameters indicates that, pyrite activated by ball milling shows the best thermal stability at the same diameter. By comparing and analyzing the X-ray diffraction patterns, results show that different mechanical activation ways played different roles in structural changes of pyrite.
文摘The effects of mechanical activation in a planetary mill on the structural changes and microstructural characteristics of the components of ferruginous quartzite beneficiation railings generated by wet magnetic separation process were studied using X-ray and laser diffraction methods. The results revealed the relationship between variations in the mean particle size of activated powders and the milling time. The crystallite size, microstrain, lattice parameters and unit cell volumes were determined for different milling times in powder samples of quartz, hematite, dolomite, and magnetite from the beneficiation tailings. The main trends in the variation of the crystallite size of quartz, hematite, dolomite, and magnetite as a function mean particle size of powder samples were revealed. Changes in the particle shape as a function of the activation time was also investigated.
文摘A mechanical activation process was introduced as a facile method for producing nickel oxide nanopowders. The precursor compound Ni（OH）2-NiCO3-4H2O was synthesized by chemical precipitation. The precursor was milled with NaCl diluent. A high-energy ball milling process led to decomposition of the precursor and subsequent dispersal in NaCl media. Nickel oxide nanocrystalline powders were produced by subsequent heat treatment and water washing. Milling rotation speed, milling time, ball-to-powder ratio （BPR）, and nickel chlo-ride-to-precursor ratio were introduced as influential parameters on the wavelength of maximum absorption （λmax）. The effects of these pa-rameters were investigated by the Taguchi method. The optimum conditions for this study were a milling rotation speed of 150 r/min, a mill-ing time of 20 h, a BPR of 15/1, and a NaCl-to-powder weight ratio （NPR） of 6/1. In these conditions,λmax was predicted to be 292 nm. The structural properties of the samples were determined by field emission scanning electron microscopy, X-ray diffraction, and energy dispersive spectrometry.
基金the National Natural Science Foundation of China(nos.22008041 and 22178074)the Natural Science Foundation of Guangxi Province,China(nos.2019GXNSFDA245020 and 2020GXNSFGA297001).
文摘Spontaneously polarized crystals with intrinsic electric dipole moment have attracted immense interest as excellent functional materials for extensive applications.It is of great significance to engineer sustainable spontaneously polarized materials with fascinating characteristics and performance for activating air and water.Herein,a novel strategy based on the synergy of mechanical activation(MA)and biomimetic mineralization(BM)was created to construct spontaneously polarized ceramic.MA induced the structural damage of clay and promoted the dissolution of ions and the release of free proteins,contributing to the formation of silicate precursor in BM process.After high temperature firing,the silicate precursor in clay was converted to form KCa_(3)AlCa_(3)Si_(4)O_(16)(hexagonal crystal system,L^(6)symmetry type,and P63 space group)in the resulting spontaneously polarized ceramic.The non-centrosymmetric structure of KCa_(3)AlCa_(3)Si4O_(16)and the high intrinsic electric dipole moments contributed by K(1)polyhedrons resulted in high spontaneous polarization(0.2322μC/cm^(2))and far-infrared emissivity(0.951)of spontaneously polarized ceramic.In air,spontaneously polarized ceramic can activate H_(2)O and O_(2)molecules to form negative air ions owing to surface electric field.In water,spontaneously polarized ceramic can disaggregate large water clusters to form small water clusters ascribed to surface electric field and far-infrared emission;water pH can be regulated from weak acidity to approximate neutrality via the capture of electrons by H+ions to produce releasable hydrogen gas.This work provides great promise for rational design and synthesis of spontaneously polarized materials for functional applications.
文摘Fifty hours of mechanical activation of mixed oxides at room temperature did not trigger the formation of Nd BaPbO 3 (BPO) in the existence of excessive PbO, but decreased the synthesis temperature of the BPO. The crystalline of the activation derived perovskite BPO phase was further established when the activated mixture was subjected to calcination at 650 ℃. The perovskite phase was sintered to a density of 98% of theoretical value at 980 ℃ for 2 h. The sintered BPO with 0.1% Nd doped exhibits a resistivity of 2×10 -4 Ω·cm and an excellent PTC effect at Curie temperature of 750 ℃ .
