Mineral Processing
A.R. Javadi
Abstract
Carnallite, with the chemical formula KMgCl3.6H2O, is a mineral that was first discovered in the Urals Mountains in Russia. The reverse flotation has been established for carnallite processing in the current decades, and the alkyl morpholine collector is used for the removal of NaCl from carnallite using ...
Read More
Carnallite, with the chemical formula KMgCl3.6H2O, is a mineral that was first discovered in the Urals Mountains in Russia. The reverse flotation has been established for carnallite processing in the current decades, and the alkyl morpholine collector is used for the removal of NaCl from carnallite using the reverse flotation. The carnallite processing method involves reverse flotation with the dodecyl morpholine collector, and then centrifugation and cold crystallization. In this research work, kimiaflot 619, as a new collector, is synthesized, and the bench-scale flotation shows that kimiaflot 619 reveals a better selectivity and affinity for the NaCl crystals at an acidic pH with a less collector dosages–only 1/2 of the Armoflot 619 collector. The flotation results indicate that the NaCl grade in carnallite concentrated by Armoflot 619 (200 g/t) is 2.86%, while the NaCl grade in carnallite concentrated by kimiaflot 619collector (100 g/t) is 2.75%. The frother’s stability of the Armoflot 619 collector after flotation is very high and uncontrollable, while kimiaflot 619 has solved this problem, and it is completely controllable.
Mineral Processing
S. Kolahi; M. Jahani Chegeni
Abstract
The number of lifters of mill shell liners, mill rotation speed, and filling percentage of grinding media are three of the most important parameters influencing the charge behavior and the trajectory of ball motion inside the SAG mills, and consequently, their performance. In this paper, the milling ...
Read More
The number of lifters of mill shell liners, mill rotation speed, and filling percentage of grinding media are three of the most important parameters influencing the charge behavior and the trajectory of ball motion inside the SAG mills, and consequently, their performance. In this paper, the milling operation of pilot-scale SAG mills using the discrete element method (DEM) is investigated. First, a pilot-scale SAG mill with dimensions of 3.0 m × 1.5 m with no lifter is simulated. Then by adding, respectively, one, two, four, eight, sixteen, and thirty-two rectangle lifter(s), six other independent simulations are performed. The effects of the number of lifters on the two new parameters introduced by the authors, i.e. ‘head height’ and ‘impact zone length’ as well as on creation of cascading, cataracting, and centrifuging motions for balls at two different mill speeds, i.e. 70% and 80% of its critical speed (NC), are evaluated. Also in order to validate the simulation results, a laboratory-scale SAG mill is simulated. The results obtained indicate that the optimum number of lifters for pilot-scale SAG mills is between 16 and 32 lifters with medium thickness. Liners with the number of lifters in this range require less mill speed to create cataract motions. However, liners with the number of lifters less than this range require a higher mill speed. Also liners with the number of lifters beyond this range require less mill speed, and can cause centrifugal motions in the balls. Comparison of the simulations related to the laboratory-scale SAG mill with experimental results demonstrates a good agreement, which validates the DEM simulations and the software used.
Mineral Processing
S. Mohammadi; B. Rezai; A. A. Abdolahzadeh
Abstract
Geometallurgy tries to predict the instability the behavior of ores caused by variability in the geological settings, and to optimize the mineral value chain. Understanding the ore variability and subsequently the process response are considered to be the most important functions of an accurate geometallurgical ...
Read More
Geometallurgy tries to predict the instability the behavior of ores caused by variability in the geological settings, and to optimize the mineral value chain. Understanding the ore variability and subsequently the process response are considered to be the most important functions of an accurate geometallurgical study. In this paper, the geometallurgical index is presented as a new tool to optimize the mining activities. Geometallurgical index is described as any geological feature that makes a footprint on the process performance of ores. In a comprehensive research work at the Sarcheshmeh porphyry copper mine, the geological features that affect the main process responses including the product grade and recovery and plant’s throughput are subjected to investigation. In the current report, the rock hardness variability in terms of semi-autogenous grinding power index (SPI) and its effects on the mill throughput and energy consumption are presented. Ninety samples are collected based on the geological features including lithology, hydrothermal alteration, and geological structures. The samples are mineralogically characterized using XRD, XRF, and electron and optical microscopy. The Starkey laboratory mill, commercialized by Minnovex, is used to perform the SPI comminution test. The SPI results show a wide range of hardness, varying from 12 to 473 minutes. The correlation between the SPI results and the geological features show that lithology is a key geological feature that defines the hardness variability. In addition, the hydrothermal alteration would be an effective parameter in the period that the plant is fed with a single lithology.
Mineral Processing
M. Jahani Chegeni; S. Kolahi
Abstract
The shell liner type, rotation speed, and ball filling percent are the key factors influencing the charge behavior inside the SAG mills, and consequently, their performance. In this work, the milling operation of industrial SAG mills is investigated using the Discrete Element Method (DEM). First, an ...
Read More
The shell liner type, rotation speed, and ball filling percent are the key factors influencing the charge behavior inside the SAG mills, and consequently, their performance. In this work, the milling operation of industrial SAG mills is investigated using the Discrete Element Method (DEM). First, an industrial SAG mill with dimensions of 9.50 m × 4.42 m that has a Smooth-type liner is simulated. Then by changing the liner types, i.e. Wave, Rib, Ship-lap, Lorain, Osborn, and Step liners, six other independent simulations are performed. In order to investigate the impact mechanism and improve the mill performance, two new parameters called ‘head height’ and ‘impact zone length’ are introduced. Then the effects of the mill shell liner type on those parameters at two different mill speeds, i.e. 70% and 80% of its critical speed (CS), are evaluated. Also for validation of the simulation results, a laboratory-scale SAG mill with dimensions of 57.3 cm × 16.0 cm is simulated. The results obtained indicate that the Osborn liner, due to the angularity of its lifters and their proper number and thickness, performs best because it increases both parameters more than the other liners. Thus this liner is recommended as the best and optimal liner in this research work and is suggested for installation inside the industrial SAG mills. Also the Wave liner, due to its specific geometrical shape and its wavy lifters as well as their low number and inadequate thickness, provides the lowest charge ‘head height’. Therefore, it is not recommended to install this liner inside the industrial SAG mills. Meanwhile, comparison of the simulations related to the laboratory-scale SAG mill with the experimental results demonstrates a good agreement that validates the DEM simulations and the software used.
Mineral Processing
A.H. Rezaei; H. Abdollahi; M. Gharabaghi; A. A. Mohammadzadeh
Abstract
In the recent decades, water scarcity has become a major challenge for many reasons, especially the inadequate use of water resources. The mineral processing plant is among the most important water-consuming industries. Filtration, as one of the important processes in water recovery, is a process in ...
Read More
In the recent decades, water scarcity has become a major challenge for many reasons, especially the inadequate use of water resources. The mineral processing plant is among the most important water-consuming industries. Filtration, as one of the important processes in water recovery, is a process in which the solid-suspended particles are removed from the liquid. In the present work, the effect of the additives affecting the filtration process upon the responses including the resistance to filter cloth (R), specific cake resistance (α), moisture content, water recovery rate, and cake formation rate by the vacuum top-feed method is investigated. The experiments are performed by two methodologies: one-factor-at-a-time and statistical analysis. The additives are the flocculant, coagulant, surfactant, and filter aid. According to the one-factor-at-a-time methodology, the optimal type and dosage of the variables are as follow: flocculant A25 with a concentration of 15 g/L, perlite as the filter aid with an amount of 2.5%, surfactant cop 20-101 with a concentration of 3 cc/L, and the coagulant CaCl2.2H2O with a concentration of 2.5 g/L. The usage of the flocculant, surfactant, and filter aid at the same time is also statistically analyzed with the aim of maximizing the cake formation rate and minimizing the moisture content of the filter cake. Under the optimal conditions and taking into account 11.68 g/t of the flocculant A25, 3.8% of perlite as the filter aid, and2.92 cc/L of the surfactant cop 20-101, the cake formation rate and the moisture content were obtained to be 0.297 mm/s and 12.7 %, respectively.
Mineral Processing
B. Nemati Akhgar; A. Fathzade; B. Golizadeh; S. Hajilou
Abstract
The flotation circuit in Sungun copper plant consists of two column flotation cells as cleaner, having fixed-spargers system. To achieve the expected aims in flotation step, there are serious operational challenges such as: fast choking of the static mixers, boiling problem, burping phenomena and pulp ...
Read More
The flotation circuit in Sungun copper plant consists of two column flotation cells as cleaner, having fixed-spargers system. To achieve the expected aims in flotation step, there are serious operational challenges such as: fast choking of the static mixers, boiling problem, burping phenomena and pulp overflow to concentrate lander, maintenance and control problems. An attempt was exerted by implementing new helical static mixer in one of cleaner cells instead of old elliptical type to overcome the challenges. The changes resulted in proper performance of the column whereas burping phenomena due to choking was eliminated, finer bubbles were produced, and the boiling and overflow problems were solved. Also, the static mixers life time increased to 7 months in helical column cells from one month in elliptical column cells. In addition to 40% air consumption reduction and 20% solid percent increase in final product, the grade of Cu and Mo increased by helical static mixer replacement up to about 18.7% from 16.8% (11%) and to 511.1 ppm from 263 ppm (94%) in the cleaner step, respectively. Recovery of Cu and Mo were increased about 1.5% and 0.2%, respectively. Finally, the results proved the effectiveness of finer bubble generation on grade improvement is depend on minerals hydrophobicity as Mo grade increased more than Cu.
Mineral Processing
H. Jafari; H. Abdollahi; M. Gharabaghi; A.A. Balesini
Abstract
In this research work, solvent extraction and stripping of zinc ions from a Zn-Mn-Cd-bearing solution was investigated using D2EHPA as the extractant in a chloride medium. The efficiency of the extraction and stripping stages was evaluated separately, and different parameters such as the pH, extractant ...
Read More
In this research work, solvent extraction and stripping of zinc ions from a Zn-Mn-Cd-bearing solution was investigated using D2EHPA as the extractant in a chloride medium. The efficiency of the extraction and stripping stages was evaluated separately, and different parameters such as the pH, extractant concentration, reaction temperature, and contact time were studied. Based on the results obtained, 97% of zinc, 14% of manganese, and 3% of cadmium were extracted at pH = 2.5, 10% (v/v) of D2EHPA, and 40 °C from the solution containing 5 g L-1 of each metal ion. The stripping isotherms of zinc, manganese, and cadmium at different pH values showed that manganese and zinc were stripped at two different pH values. Thus more than 70% of manganese and more than 90% of zinc were stripped at pH = 2.5 and pH = 0.5, respectively. Kinetic studies indicated that the extraction and stripping of zinc in the first 0.5-1 minute was high. The McCabe–Thiele diagrams showed that two stages of extraction and two stages of stripping in the continuous counter-current flow condition were adequate to separate zinc from Mn and Cd. The dominant Zn species extracted by D2EHPA was ZnCl+, and the values for the thermodynamic parameters ΔHo, ΔSo, and ΔGo were 25.65 kJ mol−1, 79.20 J K−1 mol−1, and 0.86 kJ mol−1, respectively, which showed that the reaction was endothermic at equilibrium.
Mineral Processing
P. Karimi; A. Khodadadi Darban; Z. Mansourpour
Abstract
Low-intensity magnetic separators are widely used in the research works and the industry. Advancement in the magnetic separation techniques has led to an expansion in the application of this method in different fields such as enrichment of magnetic mineral, wastewater treatment, and medicine transfer ...
Read More
Low-intensity magnetic separators are widely used in the research works and the industry. Advancement in the magnetic separation techniques has led to an expansion in the application of this method in different fields such as enrichment of magnetic mineral, wastewater treatment, and medicine transfer in the human body. In the mineral processing industry, the main application of wet magnetic separation is via drum separators. The design of this separator is based on drum rotation inside a tank media, where a permanent magnet placed inside the drum as an angle form produces a magnetic field. In the present work, the magnetic variables involved (magnetic flux density, intensity of magnetic field, and gradient of magnetic field intensity) were simulated in the drum wet low-intensity magnetic separator using the finite element method and a COMSOL Multiphysics simulator; these variables were further validated through the measured data. A comparison between the simulation and laboratory measurements (of the magnetic field) showed that the mean value of the simulation error in 94 points in 2 sections was equal to 9.6%. Furthermore, the maximum simulation error in the middle of the magnets, as the most important part of the magnetic field distribution in the process of magnetic separation, was in the 6th direction and equal to 7.8%. Therefore, the performed simulation can be applied as a first step to design and construct more advanced magnetics separators.
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.
