Mineral Processing
S. Ghasemi; A. Behnamfard; R. Arjmand
Abstract
The Sangan processing plant consists of four consecutive low-intensity magnetic separation steps with the same magnetic field intensity of 1300 Gauss for upgradation of iron ore. Hence, the iron ore minerals with lower magnetic susceptibility or interlocked with gangue minerals have no opportunity for ...
Read More
The Sangan processing plant consists of four consecutive low-intensity magnetic separation steps with the same magnetic field intensity of 1300 Gauss for upgradation of iron ore. Hence, the iron ore minerals with lower magnetic susceptibility or interlocked with gangue minerals have no opportunity for upgradation, and proceed to the tailing dam. Flotation is a powerful technique for upgradation of these materials, and it is the focus of this research work. A sample of 43.09% Fe and 12.1% FeO was taken from the tailings of second step of magnetic separation. The ore minerals of the sample were determined to be magnetite and hematite. A concentrate of 67% Fe and mass recovery of 50% was produced through the Davis tube test. A reverse flotation route was selected for upgradation of the sample. Fatty acid-based anionic collectors with trade names Alke and Dirol were used in the flotation experiments. The design of experiments was done by resolution IV fractional factorial design with nine factors at two levels per factor. A resolution IV design allows discrimination of all main effects and two-factor interactions. A concentrate of 53.92% Fe at a mass recovery of 60% was obtained at optimum flotation conditions of solid content 20%, pH 12, collector concentration of 1 kg/t, starch as depressant at a concentration of 5 kg/t, Alke/Dirol collector mass ratio of 30/70, conditioning time of 10 min., and concentration of Ca2+ as activator 1 kg/t. In this research work, the concept of natural depression of iron minerals in the reverse flotation was introduced and evaluated.
Mineral Processing
H. Ebadi; P. Pourghahramani; E. Dehgani; M. Ganjeh
Abstract
In this work, the effects of temperature, acid concentration, and mechanical activation on dissolution of ilmenite were studied using the statistical design of experiment technique. Mechanical activation was carried out using a planetary ball mill in dry mode, and the resulting structural changes were ...
Read More
In this work, the effects of temperature, acid concentration, and mechanical activation on dissolution of ilmenite were studied using the statistical design of experiment technique. Mechanical activation was carried out using a planetary ball mill in dry mode, and the resulting structural changes were characterized by the particle size analysis, specific surface area measurements, and X-ray diffraction method. The results obtained indicated that intensive milling led to a significant decrease in the ilmenite particle size and that after 20 minutes, particles tended to agglomerate. However, after 90 minutes, the BET specific surface area increased to 9.36 m2/g. In addition to surface changes, mechanical activation led to intense changes and disorders in the crystal structure of ilmenite as amorphization degree increased to 94.30% and the volume weighted crystallite size and lattice strain changed from 346 nm and 0.13% to 14 nm and 1.44%, respectively. The results of the dissolution tests in the form of experimental design indicated that a suitable model could fit the experimental data in 95% confidence level. The coefficient factors for acid concentration, mechanical activation, and temperature were 3.75%, 33.04%, and 9%, respectively. Mechanical activation had the highest effect on titanium extraction in comparison to the other factors involved. Also in addition to its dominant effect on ilmenite dissolution, it also weakened the temperature effect. However, the results of the kinetic tests proved that mechanical activation led to promotion of the temperature effect on increasing the dissolution reaction rate in the initial stages. Finally, a dissolution yield of more than 98% was achieved through 90 minutes of activation at 95° C and 55 wt.% acid concentration.
Mineral Processing
K. Barani; M. Azghadi; M. R. Azadi; A. Karrech
Abstract
The influence of microwave treatment on the surface roughness, hydrophobicity, and chemical composition of galena was studied. The pure galena specimens and purified galena concentrate were used in this work. A conventional multi-modal oven (with a frequency of 2.45 GHz and a maximum power of 900 W) ...
Read More
The influence of microwave treatment on the surface roughness, hydrophobicity, and chemical composition of galena was studied. The pure galena specimens and purified galena concentrate were used in this work. A conventional multi-modal oven (with a frequency of 2.45 GHz and a maximum power of 900 W) was used to conduct the experiments. The results obtained from the atomic-force microscopy analysis showed that the surface roughness of galena decreased after the microwave radiation. The results also showed that the surface hydrophobicity of galena increased with increase in the duration of the microwave radiation, which was in good agreement with the micro-flotation mass recovery results. The increased surface hydrophobicity may be attributed to the decreased surface roughness by microwave radiation or formation of sulfur on the surface. The results of the SEM/EDS analyses indicated that after microwave radiation, the amount of S increased, whereas Pb decreased on the surface of galena, indicating that the average atomic number of the galena surface changed due to microwave treatment.
Mineral Processing
M. R. Khani; M. Karamoozian
Abstract
In the present work, we investigated and optimized the digestion efficiency, A/S (Al2O3/SiO2 in red mud), and N/S (Na2O/SiO2 in red mud) of mixed bauxite in Iran Alumina Company using the Bayer process. Digestion experiments were carried out in an induction rotary autoclave on a mix of Jajarm, Yazd, ...
Read More
In the present work, we investigated and optimized the digestion efficiency, A/S (Al2O3/SiO2 in red mud), and N/S (Na2O/SiO2 in red mud) of mixed bauxite in Iran Alumina Company using the Bayer process. Digestion experiments were carried out in an induction rotary autoclave on a mix of Jajarm, Yazd, Tash, and Shirin Cheshmeh bauxites. A 4-factor 3-level response surface methodology was applied for the design and analysis of the experiment with the optimization of Na2O concentration, digestion temperature, residence time, and amount of lime addition. Towquadratics and one linear model were derived for the prediction of digestion efficiency, and A/S and N/S responses. The results obtained showed that the optimum amounts for Na2O concentration, temperature, amount of lime addition and residence time were 180 g/L, 275°C, 7.73%, and 50 minutes, respectively, in which the digestion efficiency, A/S, and N/S reached 72.05%, 1.169, and 0.27, respectively. Validation experiment showed that the digestion efficiency, A/S, and N/S were 72.24%, 1.162, and 0.28% respectively, which meant a 2% increase in digestion efficiency and a 0.09 and 0.02 decrease in A/S and N/S, respectively, compared to the current operating condition.
Mineral Processing
A. Abbasi Gharaei; B. Rezai; H. Hamidian Shoormasti
Abstract
According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based ...
Read More
According to the classification of the nickel laterite, this paper describes mineralogy test is to reveal where valuable elements are located in the ore, in which mineralogical form. The purpose of the sieving test was to study if some specific particle size contains most of the valuable metals. Based on its chemical composition nickel laterite is classified as a limonite type and the nickel and cobalt content was 0.7 and 0.04%, respectively. Nickel is predominantly associated with hematite and goethite. Based on the mineralogical analysis of the ore, it is observed that remarkable part of nickel is located in hematite. Therefore, nickel cannot be released from hematite lattice. The nickel content in the laterite was 0.7% and the cobalt content 0.04%. The chemical composition of laterite equals with the occurrence of 38.9% iron oxides, 26.9% carbonates, 26.9% quartz, 4.8% chromite, 2.7% magnetite and 1.9% other minerals. EDS line profile analyses were completed on hematite/goethite ooids and there was a slight correlation in the quantities between iron and nickel in each individual ooid. However, iron and nickel do not always show a positive correlation. Nickel grade could be enriched from 0.7 wt.-percent to 0.91 wt.-percent; however nickel recovery was only 45%.
Mineral Processing
M. Maleki Moghaddam; E. Arghavani; A.R. Ghasemi; S. Banisi
Abstract
Liner design has become an increasingly more important tool for the AG/SAG mill performance optimization. The Sarcheshmeh copper complex concentration plant uses a SAG mill lined with 48 rows of Hi-Low type liners. Because of breakage of Low type liners and cold welding, the liner replacement task of ...
Read More
Liner design has become an increasingly more important tool for the AG/SAG mill performance optimization. The Sarcheshmeh copper complex concentration plant uses a SAG mill lined with 48 rows of Hi-Low type liners. Because of breakage of Low type liners and cold welding, the liner replacement task of Low with new Hi type liners has become very difficult and time-consuming. With the objective of finding a new design for liners, numerical (3D DEM; discrete element method) simulation and physical modelling in a laboratory mill were used. It was found that changing the liner type from Hi-Low to Hi-Hi could provide an appropriate charge trajectory. The new Hi-Hi type shell liners were designed, manufactured, and installed. With the new liners, the number of broken liners over liner life reduced from 6 to 0 piece, the total changing time for one liner decreased from 21 to 16 minutes, and no cold welding of shell liners was observed. Comparison of the feed rate before and after installation of the new liners for a period of liner life showed an increase from 750 to 850 t/h, which was indicative of a higher flexibility of the mill in encountering ore hardness variations.
Mineral Processing
H. Shadi Naghadeh; M. Abdollahy; A. Khodadadi Darban; P. Pourghahramani
Abstract
The Esfordi phosphate concentrate mainly contains fluorapatite, monazite, and xenotime as rare earth element (REE) minerals, accounting for 1.5% of rare earth metals. The monazite and xenotime minerals are refractory and their decomposition is only possible at high temperatures. Thus mechanical activation ...
Read More
The Esfordi phosphate concentrate mainly contains fluorapatite, monazite, and xenotime as rare earth element (REE) minerals, accounting for 1.5% of rare earth metals. The monazite and xenotime minerals are refractory and their decomposition is only possible at high temperatures. Thus mechanical activation was used in the present work for this purpose. After 90 minutes of mechanical activation, the X-ray amorphization phase and the maximum BET surface area were increased to 93.4% and 8.4 m2/g, respectively. The Williamson-Hall plot indicated that the crystallite size was decreased and the lattice strain was increased as a function of the milling intensity. A volume-weighted crystallite size of 64 nm and a lattice strain of 0.9% were achieved from the mechanically activated sample for 90 minutes. The leaching efficiency of REEs with 32% nitric acid at 85 °C was increased from 25% for the initial sample to about 95% for the activated samples. The first stage reaction rate constants for La, Nd, and Ce were increased from 8 × 10-7, 9 × 10-7,and 6 × 10-7 for the initial sample to 1.3 × 10-3, 9 × 10-4, and 7 × 10-4 for the mechanically activated samples at 60 °C, respectively. Also the apparent activation energy for La, Nd, and Ce for the initial sample was found to be about 210, 231, and 229 kJ/mol, which were decreased to 120, 91, and 80 kJ/mol, respectively, after 20 minutes of mechanical activation in an argon atmosphere. The results obtained suggested mechanical activation as an appropriate pre-treatment method for dissolution of REEs from phosphate concentrates containing refractory REE minerals at a lower cost and a higher recovery rate.
Mineral Processing
S. Khoshjavan; K. Moshashaei; B. Rezai
Abstract
In this research work, the effects of flotation parameters on coking coal flotation combustible material recovery (CMR) were studied by the artificial neural networks (ANNs) method. The input parameters of the network were the pulp solid weight content, pH, collector dosage, frother dosage, conditioning ...
Read More
In this research work, the effects of flotation parameters on coking coal flotation combustible material recovery (CMR) were studied by the artificial neural networks (ANNs) method. The input parameters of the network were the pulp solid weight content, pH, collector dosage, frother dosage, conditioning time, flotation retention time, feed ash content, and rotor rotation speed. In order to select the most efficient model for this work, the outputs of different models were compared with each other. A five-layer ANN was found to be optimum with the architecture of 8, 15, 10, and 5 neurons in the input layer, and the first hidden, second hidden, and third hidden layers, respectively, as well one neurons in the output layer. In this work, the training, testing, validating, and data square correlation coefficients (R2) were achieved to be 0.995, 0.999, 0.999, and 0.998, respectively. The sensitivity analysis showed that the rotor speed and the solid weight content had the highest and lowest effects on CMR, respectively. It was verified that the predicted ANN values coincided very well with the experimental results.
Mineral Processing
M. Noori; R. Dehghan
Abstract
In the Tabas coal preparation plant (SE Iran), -50 + 6 mm raw coal was treated in a 700 mm two-stage two-density Tri-Flo dynamic dense medium separator. In order to study the circuit performance and to evaluate the separator efficiency, 32 mm cubic density tracers were used in the range of 1.28-2.1 g/cm3 ...
Read More
In the Tabas coal preparation plant (SE Iran), -50 + 6 mm raw coal was treated in a 700 mm two-stage two-density Tri-Flo dynamic dense medium separator. In order to study the circuit performance and to evaluate the separator efficiency, 32 mm cubic density tracers were used in the range of 1.28-2.1 g/cm3 and under different operational conditions. The performance of Tri-Flo was evaluated in a rapid manner, and an acceptable partitioning performance was observed under the process regime; the misplacements were in the normal range. Contrary to the dense media cyclones where the cut point shift (CPS) is usually positive, the results of this work showed that CPS was negative in both stages of the Tri-Flo separator. The Ecart probable value for the first stage of the separator (Epf = 0.023) was rather greater than the second stage (Eps = 0.018), representing the higher performance achieved in the second stage. In addition, the Tri-Flo operational parameters were found to be adjustable on the basis of raw coal specifications in order to reach good metallurgical results. Therefore, the optimum operational feed capacities of the Tri-Flo separator were determined to be in the range of 80-140 t/h, depending on the type of raw coal.
Mineral Processing
V. Radmehr; Seyed Z. Shafaei; M. Noaparast; H. Abdollahi
Abstract
This paper presents a new approach for flotation circuit design. Initially, it was proven numerically and analytically that in order to achieve the highest recovery in different circuit configurations, the best equipment must be placed at the beginning stage of the flotation circuits. The size of the ...
Read More
This paper presents a new approach for flotation circuit design. Initially, it was proven numerically and analytically that in order to achieve the highest recovery in different circuit configurations, the best equipment must be placed at the beginning stage of the flotation circuits. The size of the entering particles and the types of streams including pulp and froth were considered as the basis for specialization of the flotation processes. In the new approach, the flotation process plays as the two functions of primary and secondary concentrations. The proposed approach was applied to a lead flotation circuit of a lead-zinc flotation plant. The results obtained showed that in most traditional-oriented circuits, a large part of the streams containing valuable metals were returned to the rougher stage, which, in turn, reduced the efficiency and caused perturbation. In the new approach, providing more control over unit operations in the circuit could provide a higher performance. In addition, in cases where zinc minerals are liberated from their gangue in coarse size, the new approach, by generating coarse-grained tailing, can prevent excessive grinding of zinc minerals in the feed into the zinc flotation circuit.
Mineral Processing
Y. Kianinia; M. R. Khalesi; M. Abdollahy; A. Khodadadi Darban
Abstract
Processing of gold ores with high sulfide minerals is problematic as they consume cyanide and reduce gold leaching. Optimization of gold leaching and cyanide consumption requires a methodology to estimate the amount of exposed cyanicides, their leaching kinetics, and speciation of cyanide complexes that ...
Read More
Processing of gold ores with high sulfide minerals is problematic as they consume cyanide and reduce gold leaching. Optimization of gold leaching and cyanide consumption requires a methodology to estimate the amount of exposed cyanicides, their leaching kinetics, and speciation of cyanide complexes that consume the free cyanide and compete with gold. In this paper, a physico-chemical approach is presented to estimate the liberation and exposure of cyanicides to the leaching solution, and then prediction of the speciation of all possible related species in the solution. The results obtained show that this methodology not only could successfully estimate the gold leaching and cyanide consumption based on the mineralogical data with a lower number of parameters compared to existing empirical models, but also offers the prediction of formation of all the possible complexes that could be used for optimization purposes.
Mineral Processing
M. Jahani Chegeni
Abstract
A deeper understanding of the milling operation of ball mills helps mineral processing engineers to control and optimize them, and therefore, reduce their consuming power. In this work, the milling operation of ball mills is investigated using two methods, i.e. DEM and combined DEM-SPH. First, a pilot ...
Read More
A deeper understanding of the milling operation of ball mills helps mineral processing engineers to control and optimize them, and therefore, reduce their consuming power. In this work, the milling operation of ball mills is investigated using two methods, i.e. DEM and combined DEM-SPH. First, a pilot scale ball mill with no lifter is simulated by both methods. Then another pilot scale ball mill with eight rectangle lifters is simulated again by both methods. The effects of lifters on ball shoulder and toe points as well as on creation of cascading and cataracting movements for balls are studied by both methods. At the present time, there is not enough measured data available for dense slurries interacting with the coarse particulates available in the public domain that can be used adequately to validate these types of predictions. The results obtained indicated that fluid slurry in the mill lowered the charge shoulder by about 28 cm and 25 cm in the no-lifter and eight-lifter cases, respectively. However, it raised the charge toe by about 36 cm and 6 cm in the no-lifter and eight-lifter cases, respectively.
Mineral Processing
A. Behnamfard; E. Khaphaje
Abstract
Beneficiation of a low-grade iron ore was investigated by combination of the low-intensity magnetic separation and reverse flotation methods. The main constituents of the representative sample were 36.86% Fe, 8.1% FeO, 14.2% CaO, 13.6% SiO2, and 0.12% S based on the X-ray fluorescence, titration, and ...
Read More
Beneficiation of a low-grade iron ore was investigated by combination of the low-intensity magnetic separation and reverse flotation methods. The main constituents of the representative sample were 36.86% Fe, 8.1% FeO, 14.2% CaO, 13.6% SiO2, and 0.12% S based on the X-ray fluorescence, titration, and Leco analysis methods. The mineralogical studies by the X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe micro-analyzer, and Fe/FeO titration methods showed that the ore minerals present in the representative sample were magnetite, hematite, and goethite, and the main gangue minerals were calcite and quartz. The effects of the operating parameters including the feed size, solid content, and drum rotation speed were investigated on the performance of the wet low-intensity magnetic separation (WLIMS). The optimum operating conditions of WLIMS were determined to be feed size = 135 μm, solid content = 40%, and drum rotation speed = 50 rpm. Under these conditions, a concentrate of 62.69% Fe grade and 55.99% recovery was produced. The tailing of WLIMS with an iron grade of 28.75% was upgraded by reverse flotation with fatty acids as the collector. The effects of five parameters on two levels were investigated using the 25-1 fractional factorial design in 16 experiments. The optimum flotation conditions were determined to be pH = 12; dosage of collector, 1 kg/t; dosage of Ca2+ as activator, 4 kg/t; and dosage of starch as depressant, 1 kg/t. Under these conditions, a concentrate of 53.4% Fe grade and 79.91% recovery was produced.
Mineral Processing
A.R. Ghasemi; A.R. Hasankhoei; E. Razi; Gh.A. Parsapour; S. Banisi
Abstract
Pelletizing plant of the Gol-E-Gohar mining and industrial company consists of a burner, a dry ball mill (6.2 m × 13 m), and an air separator. The ball mill consists of a 2 m-long drying and an 11 m-long grinding chambers. The iron ore concentrate is fed to the drying chamber by a feed chute. It ...
Read More
Pelletizing plant of the Gol-E-Gohar mining and industrial company consists of a burner, a dry ball mill (6.2 m × 13 m), and an air separator. The ball mill consists of a 2 m-long drying and an 11 m-long grinding chambers. The iron ore concentrate is fed to the drying chamber by a feed chute. It was found that when the feed moisture content increased from 1.3% to 3.5%, the throughput decreased by 12% (35 t/h) indicating a low performance of the dryer. Monitoring the wear rate of flights for a period of 12 months showed that the first 0.8 m (59%) length of the dryer length did not experience any wear. To overcome this problem, various feed chute designs with different geometries were simulated by the KMPCDEM© software. With the aim of arriving at a proper material trajectory, where the total length of the dryer is used, a new feed chute was selected. The simulation results indicated that if the height of the feed chute is increased from 1.60 to 2.26 m and the slope is increased from 45 to 48 degrees the material arrives at the first 0.48 m of the drying chamber. In this manner, the unused part of the drying chamber decreases from 59% to 36% of the length. After installation of the new feed chute during a period of three months, the throughput increased by 36 t/h.
Mineral Processing
D. Ghoddocy Nejad; M. Taghizadeh; A. R. Khanchi
Abstract
In this work, thealkaline roasting and sulfuric acid leaching processes were employed to extract vanadium from the magnetite ore of Saghand mine in central Iran. The response surface methodology based on the central composite design model was applied to optimize the parameters involved in the processes. ...
Read More
In this work, thealkaline roasting and sulfuric acid leaching processes were employed to extract vanadium from the magnetite ore of Saghand mine in central Iran. The response surface methodology based on the central composite design model was applied to optimize the parameters involved in the processes. The studied roasting parameters were temperature (900-1100 °C), sodium carbonate percentage (30-50 wt%), and time (1-3 h). In addition, the studied leaching factors included temperature (70-90 °C), liquid-to-solid ratio (L/S) (5-20 mL/g), sulfuric acid concentration (2-6 M), and time (3-6 h). Under the optimal conditions, the values for temperature, time, and sodium carbonate amounted to 1010 °C, 2.1 h, and 41 wt%, respectively, for the roasting process, while the values for temperature, L/S, sulfuric acid concentration, and time for the leaching process were estimated to be 85 °C, 12.4 mL/g, 4.25 M, and 4.7 h, respectively. Under these conditions, about 83.8 ± 0.9% of vanadium was leached from the magnetite ore.
Mineral Processing
G.G. Berhe; A. Velázquez del Rosario; Y. Abubeker; W. Girma; T. Bogale; C. Mulugeta Sisay
Abstract
The decomposition of the Ethiopian Kenticha tantalite ore was studied using the KOH fusion and H2O leaching system at 400 0C for a 1 h reaction time. The experimental results obtained showed that 27 wt% of Ta2O5 was mainly transformed into insoluble KTaO3, not to be KNbO3, and as well, into the dissolved ...
Read More
The decomposition of the Ethiopian Kenticha tantalite ore was studied using the KOH fusion and H2O leaching system at 400 0C for a 1 h reaction time. The experimental results obtained showed that 27 wt% of Ta2O5 was mainly transformed into insoluble KTaO3, not to be KNbO3, and as well, into the dissolved liquor containing 94.73 vol% of Nb2O5 and 75.80 vol% of Ta2O5. The observations, supported by the EDXRF, XRD, and ICP-OES techniques, showed that the ratio of the dissolved mixture of Nb and Ta metal ions was beneficial to the solvent extraction from both Ta2O5 and Nb2O5. Niobium and tantalum were extracted from their neutralized alkaline dissolved and hydrolyzed solution by a new process using the EMIC/AlCl3 ionic liquid as the extractant using selective stripping, precipitation, and calcination of a highly crystalline pure 99.84 wt% of Nb2O5 and amophours 90.81 wt% of Ta2O5. The compositions of the dissolved metal ions and solids were analyzed by the ICP-OES, EDXRF, XRD, and FT-IR techniques.
Mineral Processing
S. Razmjooei; M. Abdollahy; M. R. Khalesi
Abstract
Flotation process in mechanical cells is carried out in highly turbulent conditions. In this work, the impact of impeller speed on four characteristics of the quiescent zone, i.e. zone height, turbulence, solid percentage, and gas holdup, and their relationship with the entrainment is investigated, and ...
Read More
Flotation process in mechanical cells is carried out in highly turbulent conditions. In this work, the impact of impeller speed on four characteristics of the quiescent zone, i.e. zone height, turbulence, solid percentage, and gas holdup, and their relationship with the entrainment is investigated, and it is shown why at a higher impeller speed, entrainment is not significant. The height of the quiescent zone and its turbulence are measured using a piezoelectric sensor, while an electrical conductivity sensor measures the gas hold-up. A peristaltic pump is applied to take samples from the pulp to measure the solid percentage. The results obtained showed that with increase in the impeller speed from 750 to 1100 rpm, the entrainment value changed from 2.01% to 5.69%. However, the variations in entrainment were not significant at speeds higher than 1100 rpm. It was found that the height of the quiescent zone was independent from the impeller speed, while raising the impeller speed, as long as the solid percentage, turbulence, and gas hold-up are increased, caused a drastic increase in entrainment. Despite the increase in the solid percentage and turbulence, the gas hold-up decreased at impeller speeds higher than 1100 rpm due to the variation in the bubble distribution pattern, so the entrainment raised with a smaller slope. Finally, a model is presented for the entrainment as a function of the three correlated variables using the Ridge regression. The entrainment is then correlated to the impeller speed, explaining the contradictory results from the literature on the effect of impeller speed on the entrainment.
Mineral Processing
S. Feizollahi; A. Azizi
Abstract
The extraction behavior of Cu(II) ions from a real sulfate liquor obtained from the heap leaching stage of a copper oxide ore was investigated using a chelating reagent, Chemorex CP-150 in kerosene. A comparative study was also carried out on the extraction capability of Cu(II) ions using other solvents ...
Read More
The extraction behavior of Cu(II) ions from a real sulfate liquor obtained from the heap leaching stage of a copper oxide ore was investigated using a chelating reagent, Chemorex CP-150 in kerosene. A comparative study was also carried out on the extraction capability of Cu(II) ions using other solvents including D2EHPA and Cyanex 272.Chemorex CP-150 demonstrated an effective and selective extraction performance of copper with the amount of extracted Fe less than 15%. Also the results obtained indicated that more than 66.4% and 96.99% of Cu were transferred to the organic phase in a single extraction stage using 15% (v/v) Chemorex CP-150 at the A:O phase ratios of 1:1 and 1:4, respectively. In addition, the McCabe-Thiele diagram exhibited that two extraction stages were required to achieve the maximum amount of Cu at a 1:1 phase ratio under the optimal conditions (25 °C, pH 2.5, and 20 min contact time). Also, thermodynamic data proved that the extraction process was slightly endothermic (ΔH = 7.62 kJ/mol), indicating the relatively smaller heat effects on the formation of a single complex species (CuR2). Stripping of copper from the loaded organic phase was also conducted, and it was found that ~99.38% copper could be recovered using 165 g/L H2SO4 at a 2:1 A:O phase ratio after 5 minutes stripping.
Mineral Processing
R. Ahmadi; E. Ravanasa; Y. Mirzapour
Abstract
In this work, adsorption of the potassium amyl xanthate collector on the pure chalcopyrite surface was studied by applying atomic force microscopy (AFM). The adsorption experiments were carried out at different concentrations of the collector and at diverse pH values in the presence or absence of exterior ...
Read More
In this work, adsorption of the potassium amyl xanthate collector on the pure chalcopyrite surface was studied by applying atomic force microscopy (AFM). The adsorption experiments were carried out at different concentrations of the collector and at diverse pH values in the presence or absence of exterior ions. The changes occurring in the surface morphology of chalcopyrite due to the collector adsorption were evaluated by measuring the contact angle of the collector and its surface coating. According to the 3D images obtained by AFM, an increase in the pH value from 7.5 to 9.5 at two concentrations of 25*10-3 and 50*10-3 g/ton of the collector would increase the number of particles adsorbed on the surface, improve the adsorption morphology, and reduce the contact angle. Moreover, at a constant pH value, increasing the collector would result in the proliferation of contact angles as well as a relative increase in the number of particles. By comparing the morphological surface changes in the tap and distilled water samples, applying tap water, owing to the presence of Cu2+ ions and activation of the surface through the production of CuS, the quality and quantity of adsorption would be increased. The use of tap water not only can account for an appropriate coating by the collector but also causes to reduce the consumption of collector for at least 50%.
Mineral Processing
M. Salehfard; M. Noaparast; Seyed Z. Shafaei; H. Abdollahi
Abstract
A lead-zinc carbonate ore sample containing 2.5% Pb and 9.39% Zn was used in this research work. The sample was prepared from the Darreh-Zanjir mine located in the Yazd province (Iran). Influences of the influential factors on flotation of smithsonite and cerussite were investigated. Among the different ...
Read More
A lead-zinc carbonate ore sample containing 2.5% Pb and 9.39% Zn was used in this research work. The sample was prepared from the Darreh-Zanjir mine located in the Yazd province (Iran). Influences of the influential factors on flotation of smithsonite and cerussite were investigated. Among the different parameters involved, dosages of the dispersant, depressants, sulfidizing agent, and collectors de-sliming prior to lead or zinc flotation were essential for the effective recovery and grade of the Zn and Pb flotation concentrates. In addition, the anionic, cationic, and mixed (cationic/anionic) collectors were employed for flotation of smithsonite. The results of reverse and cumulative flotation of both Zn and Pb were relatively low in comparison with the direct process without depressant. Flotation of smithsonite using mixed collectors (Armac C+KAX) showed promising results. Also dosages of chemicals in the cleaning stage for the Zn and Pb concentrates were optimized, and finally, after the cleaner stage for both lead and zinc, a cerussite concentrate with Pb grade and recovery of 49.82% and 60.06%, respectively, and smithsonite concentrate with Zn grade and recovery of 35.47% and 68.56%, respectively, were obtained under the optimal conditions. Furthermore, kinetics of Zn and Pb oxide mineral flotations in the rougher and cleaner stages were studied, which showed that some kinetics models, especially the classical first-order model, could predict the flotation behaviour of the Zn and Pb oxide minerals.
Mineral Processing
I. Kursun Unver; M. Terzi
Abstract
Today coal is among the most important energy sources. In order to meet the world's energy demands, low-calorie lignite with a high ash content is generally used in the large capacity coal-fired thermal power plants. As a result of coal firing, wastes such as fly ash, slag, and flue gas are also produced. ...
Read More
Today coal is among the most important energy sources. In order to meet the world's energy demands, low-calorie lignite with a high ash content is generally used in the large capacity coal-fired thermal power plants. As a result of coal firing, wastes such as fly ash, slag, and flue gas are also produced. Subsequently, toxic trace elements within coal are transferred to wastes such as slag, fly ash, and flue gases. Large amounts of these, which are usually stored in collection ponds or stockpiles, are problematic in terms of environment. Although coal fly ash (CFA) has been utilized in construction and several other industries for decades, its current ratio of utilization is still quite limited. As an important fact, CFA also contains many valuable metals including germanium (Ge), gallium (Ga), vanadium (V), titanium (Ti), and aluminum (Al). In addtion, coal and CFA can be regarded as alternative sources of radioactive elements. Therefore, they also have a great potential in terms of the precious metals and trace elements they contain. In this study, the present literature on the distribution of trace elements in coal and coal ash during firing and ore preparation processes and their recovery possibilities with mineral processing practices are reviewed. While many research works on the subject clearly indicate that the large amounts of the ashes produced from firing of coal could be problematic in terms of environment, many studies and practices also show that coal combustion products also have a great potential in terms of the precious metals and trace elements.
Mineral Processing
S. Shahraki; M. Karamoozian; A. Azizi
Abstract
Sulfur is one of the most significant impurities in coal, which reduces the quality of coal and also results in environmental pollution. This work was aimed to investigate the removal of sulfur from coal by the leaching method employing parameters expected to affect the removal rate such as acid concentration ...
Read More
Sulfur is one of the most significant impurities in coal, which reduces the quality of coal and also results in environmental pollution. This work was aimed to investigate the removal of sulfur from coal by the leaching method employing parameters expected to affect the removal rate such as acid concentration (10-30%), temperature (40-80 °C), and reaction time (40-100 min). A response surface methodology using Box-Behnken design was employed to maximize, model, and evaluate the factors affecting the desulfurization process. The results obtained indicated that the desulfurization value increased with increase in the acid concentration, temperature, and reaction time. A quadratic model with a high correlation coefficient (R2=0.98) is proposed and developed for the relationship between the removal value and the influential factors. The modeling results demonstrated that the significance degree of factors was in the order of acid concentration>temperature>reaction time. It was also found that the maximum desulfurization (about 87%) could be obtained under the optimal conditions of acid concentration=25%, temperature=80 °C, and leaching time=84 minutes.
Mineral Processing
S. G. Ozkan
Abstract
Ultrasound can be used both simultaneously or as a pretreatment technique for flotation to produce higher combustible recoveries, higher heat values, and lower ash data from raw hard coals. The recent research works have indicated that modifying coal surfaces, especially physical surface cleaning with ...
Read More
Ultrasound can be used both simultaneously or as a pretreatment technique for flotation to produce higher combustible recoveries, higher heat values, and lower ash data from raw hard coals. The recent research works have indicated that modifying coal surfaces, especially physical surface cleaning with the help of the cavitation process created by power ultrasound at certain frequency and time intervals, might cause significant changes in flotation responses by a thorough adsorption of reagents on coal surfaces. When power ultrasound is applied to a coal slurry that makes the bubbles to collapse near a coal surface, a high-speed jet of liquid is driven into the particles, and this jet may deposit enormous energy densities at the site of impact. The simultaneous ultrasonic treatment also causes significant changes in local temperatures and pressures within the slurry containing coal and a certain number of reagents at variable dosages during flotation. This treatment improves the effectiveness of reagent molecules at coal surfaces and interfaces due to their more uniform distribution in the pulp and also enhancement of the activity of the reagents used. This paper reviews the results of the recent studies and the possible mechanism of simultaneous ultrasound-assisted coal flotation.
Mineral Processing
R. Solis-Rdoriguez; S. Bello-Teodoro; A. Moreno-Baez; J. I Galvan-Tejada; J. G Arceo-Olague; H. Luna-Garcia; O. Alonso-Gonzalez
Abstract
Precious metals are currently associated with selenium (naumannite, Ag2Se) and tellurium (calaverite, AuTe2; sylvanite, (Au,Ag)2Te4) to form species refractory to cyanidation. The aim of this preliminary work was to study the use of the solvent extraction technique to recover tellurium and selenium ions ...
Read More
Precious metals are currently associated with selenium (naumannite, Ag2Se) and tellurium (calaverite, AuTe2; sylvanite, (Au,Ag)2Te4) to form species refractory to cyanidation. The aim of this preliminary work was to study the use of the solvent extraction technique to recover tellurium and selenium ions from a synthetic solution similar to the cyanidation effluents to recycle the free cyanide back to the process. For the extraction of the Se and Te anions, the use of quaternary amines as extractants was evaluated (tallow trimethyl ammonium chloride, Quartamin TPR; hexadecyl trimethyl ammonium chloride, Amine F; and trioctyl methyl ammonium chloride, Aliquat 336) employing nonylphenol as a modifier in the organic phase (iso-octane). The results obtained showed that the extraction was strongly affected by the pH and that it was possible to recover up to 83% of Se and 10% of Te with Quartamin TPR from two synthetic solutions containing 23 mg/L of Te and 20 mg/L of Se with a molar cyanide:metal ratio of 1:4 at pH 11, a ratio of aqueous/organic (A/O) = 1 (V/V) and an extractant concentration of 0.022 mol/L. A maximum distribution coefficient (D) of 4.97 was obtained at pH 11. The McCabe-Thiele diagram indicates that two theoretical extraction stages are necessary to obtain a good extraction of Se complexes using Quartamin TPR.
Mineral Processing
M. Heshami; R. Ahmadi
Abstract
The aim of this work is to investigate the effect of thermal treatment on the grinding behavior of manganese ore in the various size fractions of -1.7+1.18, -1.18+0.6, -0.6+0.3 and -0.3+ 0.15 mm. Breakage Function Determination Software (BFDS) is used to calculate the selection function of the experiment. ...
Read More
The aim of this work is to investigate the effect of thermal treatment on the grinding behavior of manganese ore in the various size fractions of -1.7+1.18, -1.18+0.6, -0.6+0.3 and -0.3+ 0.15 mm. Breakage Function Determination Software (BFDS) is used to calculate the selection function of the experiment. The results of SEM analysis show the micro-cracks in the thermally treated manganese sample, and DTA/TG analysis show that heating at 750 °C leads to dehydroxylation of montmorillonite, and decomposition of calcite and decomposition of montmorillonite to silicate minerals occur at 850 °C. Montmorillonite mineral with a hardness of 2 is turned into silicate minerals with an average hardness of 7. Therefore, it can be seen that the thermal treatment leads to a decrease in the specific rate of breakage from 1.04 min-1 to 0.65 min-1 (approximately to 37%) for a size fraction of -0.300+ 0.15 mm. It; can be expressed that the thermally treated sample is broken more slowly than the untreated sample. Also, parameter “A” is the maximum Si value, decreasing for the heated sample from 4.36 min-1 to 4.28 min-1. The selection function results show that all size fractions of this material follow a first-order kinetics.
