Ore Particle Size Research Articles

Estimating Ore Particle Size Distribution using a Deep Convolutional Neural Network

In this work the ore particle size distribution is estimated from an input image of the ore. The normalized weight of ore in each of 10 size classes is reported with good accuracy. A deep convolutional neural network, making use of the VGG16 architecture, is deployed for this task. The goal of using this method is to achieve accurate results without the need for rigorous parameter selection, as is needed with traditional computer vision approaches to this problem. The feed ore particle size distribution has an impact on the performance and control of minerals processing operations. When the ore size distribution undergoes significant changes, operational intervention is usually required (either by the operator or by an automatic controller).

Optimization of flotation columns to provide added value of local sphalerite ore

Sphalerite is the most important mineral in the formation of zinc metal. According to regulation of Ministry ESDM No.5/2017 stated that the minimum grade of zinc concentrates to be exported is 51%. Therefore, it is necessary to do a beneficiation process for sphalerite ore to fulfil the requirements. Sphalerite is hydrophobic mineral, therefore it is the best way to processed sphalerite by flotation. Flotation is the process of concentrating valuable minerals from impurities based on the nature of the mineral surface. Column flotation is a flotation technology without an agitator as a producer of air bubbles like conventional flotation machines. Recovery is the most important factor in flotation and it shows the rate of acquisition of the flotation process. The purpose of this research was to determine the effect of air flow rates (2, 2.5, 3, 3.5, and 4 L / min.), percent solid (7.5%, 10%, 12.5%, and 15%), dose of reagent frother (10, 20, 30 and 40 ppm), and particle size of ore (-80 + 100 #, -100 + 140 #, -140 + 200 #, -200 #) on ZnS recovery. The research was carried out by using a laboratory scale flotation column with 4.6 cm in diameter and 150 cm column height. The flotation reagent used was activator (CuSO4), pH regulator (NaCO3), collector (PAX), and frother (dowfroth 1012). The highest recovery (90.29%) was achieved at a flow rate of 4.0 L/min, while on variation of particle size the highest recovery was 85.55% at (-100+140) #. The increase in percent solid or dilution of pulp is not always followed by an increase in recovery and the highest recovery ((71.26%) was achieved at 7.5% solid. In addition, recovery increases with increasing doses of frother, the highest recovery (86.04%) was achieved at 40 ppm doses of frother.

Kinetics model for leaching of ion-adsorption type rare earth ores

This paper aims to establish a mathematical model that can analyze the whole leaching kinetics process of ion-adsorption type rare earth ores. This leaching process is composed of three steps: (1) ammonium ions arrive at the ore particle surface through the diffusion layer; (2) ammonium ions exchange with rare earth ions; and (3) rare earth ions enter into the external solution through the diffusion layer. In the leaching process, it is hypothesized that the ore particle size remains constant. The process of ammonium ions and rare earth ions passing through the diffusion layer was described by the Fick law, and the reversible ion exchange process between ammonium ions and rare earth ions was described by the Kerr model. A leaching kinetics model of rare earth ions by ammonium ions was constructed. Accuracy of this kinetics model was verified with laboratory tests. It is found that the correlation coefficients of all data are greater than 0.9000. The proposed kinetics model is therefore feasible for kinetics analysis throughout the leaching process.

A novel process for simultaneously extracting Ni and Cu from mixed oxide-sulfide copper-nickel ore with highly alkaline gangue via FeCl3∙6H2O chlorination and water leaching

An innovative and clean technique for simultaneously extracting Ni and Cu from mixed oxide-sulfide copper‑nickel ore using FeCl3∙6H2O chlorination was developed. This technique not only prevented environmental pollution, but also allowed the efficient recovery of valuable metals. Various roasting factors were investigated in detail to obtain the optimum conditions for the extraction of Ni and Cu: chlorination temperature of 175 °C, chlorination time of 2 h, chlorinating agent dosage of 50%, and ore particle size of 80–96 μm. After chlorination followed by water leaching, >92.33% Ni and 89.43% Cu were extracted, while, only 7.37% Fe was transferred into the leaching solution, which resulted in the Fe concentration in the leaching solution of 0.12 mol/L. The mechanism of chlorination roasting and transformation rules of the mineral phase were determined using differential thermal and thermogravimetric analysis (DTA-TG), X-ray diffraction (XRD), thermodynamic analysis of chlorination reactions, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The content of gaseous chlorinating agent produced can be controlled by the dosage of ferric chloride so that no exhaust gas is emitted. The chlorination technique using FeCl3∙6H2O provided an effective approach for the simultaneous and direct extraction of Ni and Cu from mixed oxide-sulfide copper‑nickel ore.

Comprehensive Recovery Technology for Te, Au, and Ag from a Telluride-Type Refractory Gold Mine

While extracting gold and silver from telluride-type gold deposits, it is beneficial to develop a comprehensive recovery technology for tellurium. In this paper, we report process mineralogy based on the backward processing technology and the low comprehensive utilization rate of typical telluride-type gold deposits in Xiaoqinling, China. The findings show that tellurium, gold, and silver are the most valuable elements in the ore fissures and gangue minerals and are encapsulated in metallic sulfur ore in the form of altaite, hessite, calaverite, antamokite and natural gold. The flotation method was innovatively applied in this study to comprehensively recover Te, Au and Ag. The results show that when the ore particle size was −0.074 mm (70%), the flotation pulp density was 33%, the pulp pH was 8, and the combined collector (isoamyl xanthate + ethyl thio- carbamate (1:1)) was 120 g/t, in the process involving one rough flotation step, two cleaning flotations and two scavenging flotations as well as a continuous 8 d industrial test, the recovery degree was stable and the average grades of Te, Au, and Ag were 241.61, 90.30, and 92.74 g/t with 95.42%, 97.28%, and 94.65% recovery rates, respectively; thus, excellent recovery degrees were obtained. Compared with the original flotation process, the recovery rates of Te, Au, and Ag were increased by 19.91%, 6.93%, and 5.67%, which boosted the effective enrichment of all valuable elements in the telluride-type gold mine and achieved technological progress.

Extraction of Copper and Nickel from Low-Grade Nickel Sulfide Ore by Low-Temperature Roasting, Selective Decomposition and Water-Leaching Process

Low-temperature roasting, selective decomposition and water-leaching were used to extract nickel and copper from low-grade nickel sulfide ore with highly alkaline gangue. The effects of variable factors, such as the dosage of roasting additives, the ore particle size, roasting time and roasting temperature, selective decomposition temperature and leaching temperature on the conversion of metals were investigated. The roasting process contained liquid–solid and gas–solid reactions, which were controlled by internal diffusion. X-ray diffraction analysis of the roasting clinkers presented that the metal sulfides were first converted into intermediate products of metallic ammonium sulfate salts or metal sulfate by reacting with ammonium sulfate, and finally formed stable metal-sodium double salts by the action of sodium sulfate. Proportions of 99.13% nickel and 96.74% copper can be effectively extracted, while 95.95% iron was removed by selectively decomposing iron-containing sulfates to form ferric oxide, or separating as natrojarosite in a water-leaching process.

Multi-scale impact crushing characteristics of polymetallic sulphide ores

Abstract The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead−zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer (MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower; on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.

Oxygen pressure leaching–flotation joint process for Jinbaoshan platinum group minerals

Abstract An oxygen pressure leaching–flotation joint process was proposed to treat Jinbaoshan platinum group minerals to produce a desired concentrate. The result demonstrates that leaching parameters which include particle size, stirring speed, liquid–solid ratio, and the dosage of calcium lignosulfonate, simultaneously affect the leaching rates of base metals and the recovery of platinum group metals (PGMs). The complete dissolution of base metals sulfides leads to a reduction in the amount of flotation carrier for enriching PGMs, decreasing the recovery of PGMs. The optimum leaching conditions are determined as follows: liquid–solid ratio of 10 mL/g, 73% occupancy of ore particle size below 0.043 mm, stirring speed of 400 r/min, and 0.6 g dosage of calcium lignosulfonate. Under optimal conditions, the leaching rates of Cu, Ni and Fe are 87.6%, 87.6% and 90.3%, respectively. The grade of PGMs enriched in the flotation concentrate is 420 g/t through the flotation technology.

Leaching kinetics of scheelite with sodium phytate

Considering the environmental requirements and cost of energy consumption, organic phytic acid salt, a non-toxic and non-polluted green reagent, was used to decompose scheelite. The present study investigated the leaching kinetics of scheelite ore with sodium phytate. The effects of reaction temperature, initial sodium phytate concentration, scheelite ore particle size, and stirring speed on the scheelite leaching rate were analyzed. While independent of stirring speed, it was found that the leaching rate was significantly influenced by the temperatures and particle sizes at the investigated range. The leaching data revealed that the effects of the relevant operating variables on leaching rates are consistent with the shrinking-core model, with internal diffusion being the rate-controlling step. The apparent activation energy based on the Arrhenius expression was calculated as 84.54 kJ/mol, and the kinetic equation associated with the leaching rate of scheelite was established using quadratic regression.

Research on prediction model of ore grinding particle size distribution

The prediction of grinding particle size is an effective measure to optimize the grinding process. Cassiterite polymetallic sulfide ore and lead-zinc ore, as the research object in this paper, their particle size prediction mechanism are studied based on the drop weight test, batch grinding test, the theory law of media motion in ball mill and population balance model. The results show that particle size distribution of crushing products under different crushing energies and ore particle sizes is obtained by drop weight test, and the crushing parameters A and b are calculated by fitting regression, and then the correlation between tx and t10 obtained in drop weight test is also applicable to the correlation between tx and t10 of grinding products in ball mill medium throwing motion, which can effectively solve the crushing function and the selection function with the help of Matlab, and then establish the grinding population balance prediction model based on the drop weight test and the motion law of ball mill medium. The adaptability and reliability of the prediction model of grinding particle size are verified by batch grinding test.

Assessment of grinding additives for promoting chromite liberation

Liberation of the valuable minerals of an ore from its gangue is a prerequisite for the economic recovery of the valuable minerals to concentrates. Mineral liberation is achieved by reducing the size of ore particles in various crushing and grinding devices. The fineness to which the ore must be ground, so as to yield sufficient degrees of liberation, increases if the valuable minerals with small grain sizes are disseminated throughout the gangue. Intensive fine grinding, however, increases energy costs and can lead to the loss of very fine untreatable particles into the tailings. Therefore, research should be oriented toward developing methods to foster breakage through the mineral grain boundaries to accomplish liberation at relatively coarser grinds. The purpose of this study is to determine if the pretreatment of the samples of a chromite ore with aqueous solutions of some salt and surfactant additives could improve the liberation by promoting preferential fracturing at the grain boundaries between the chromite and silicate minerals in the ore. For this purpose, untreated and pretreated samples of −9.53 + 6.35 mm size fraction of the ore were broken in a drop-weight tester, and the liberation spectra and the mass distribution of the resultant progenies were measured and compared. Optical and scanning electron microscope images and spectroscopic tools were used to find evidence for grain-boundary fracturing in the breakage progeny fragments. Results support the promoting effect of hydrolysis on grain-boundary fracturing. Aqueous salt and surfactant species enhance grain-boundary fracturing by forming surface complexes and dislocating aluminum atoms at the grain boundaries. Grain-boundary fracturing yields exposed chromite surfaces and enriched chromite content in the coarse progeny particles. The grain-boundary weakening is associated with slight hardness variation along the boundary.

Effect of particle size on uranium bioleaching in column reactors from a low-grade uranium ore

This study evaluated the effectiveness of ore particle size on column bioleaching from low-grade uranium ore using an indigenous Acidithiobacillus ferrooxidans, isolated from local uranium ore. The uranium content was 0.033% by weight and ore particle size was crushed to <50 mm, <30 mm, and <15 mm. The additive content of sulfuric acid 5 g/L, Fe3+ dosage of 5.0 g/L, spray strength of 2.57 L/(h·m2) and temperature of 25 °C were controlled. After 150 days of leaching, acid consumption amounted to 2.73 g H2SO4 per kg ore, the obtained maximum uranium extraction was 64.85% with the ore particle size of <15 mm. The results showed that a smaller particle size ore had a higher uranium extraction and that an economic uranium extraction can be obtained by correctly controlling the ore granularity.

Performance of Kulon Progo low grade manganese ore leaching using acetic acid and its selectivity

The need of manganese to support human life has led to the exploitation of low-grade manganese ore. However, the appropriate technique has not been established and still under development. Having total amount of 120 thousand metric tons, Indonesia has huge potential of low grade manganese ore deposited in several areas such as Kulon Progo, Yogyakarta. In this study, leaching of low grade manganese ore was conducted using acetic acid which isenvironmentally friendly due to its ease to decompose naturally. Ore characterization was performed by X-Ray Diffraction (XRD), X-Ray fluorescence (XRF), and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) showing that 7.16 % is manganese while 32 % of the ore is dominated with calcite. Effects of leaching temperature and particle size on Kulon Progo low grade manganese ore were investigated. Particle sizes under study were less than 200 mesh and between 70 mesh and 100 mesh. The pH and temperature of experiment were varied on 0.7, 1.7, and 3; and 30 °C, 60 °C and 80 °C, subsequently. It was obtained that the ore particle size has no significant effect on Mn recovery. The manganese recovery of 76.08 % was obtained, containing lower recovery of calcium and iron which were 10%. The findings showed acetic acid is more selective towards manganese than to calcium and iron.

Leaching of El-Missikat low-grade fluoritized uranium ore by sulfuric acid: mechanism and kinetic

A well-characterized low-grade fluoritized uranium samples from new occurrence in Gabal El-Missikat prospect, Eastern Desert, Egypt was subjected to sulfuric acid leaching. The effects of leaching parameters on uranium dissolution mechanism were investigated. The shrinking core model was used to model leaching reactions. The kinetics equations indicates that the reactions appear to be controlled by layer diffusion process. The activation energy for uranium dissolution was evaluated. Low activation energy value (2.54 kJ mol−1) confirm the diffusion layer mechanism. The presence of fluoride ions in the solution increases the dissolution of uranium. The optimum process operating parameters were: sulfuric acid concentration: 1.5 M, solid–liquid ratio: 1:3, contact time 8 h; agitation speed rate 200 rpm; and ore particle size − 75 µm at temperature 60 °C, in the absence of an external oxidant. Under these experimental conditions, the extraction efficiency of uranium was about 91%.

Ore particle size classification model based on bi-dimensional empirical mode decomposition

The frequency domain information of ore multi-scale image is difficult to distinguish boundary and texture details of ore objects, and hard to apply to particle size detection. Particle size classification model based on Bi-dimensional empirical mode decomposition (BEMD) is proposed, which is applied to particle detection of multi-size scenarios. Different size fraction ore images’ local frequencies are extracted by BEMD reflecting the edge and texture features. The instantaneous frequencies of each high-frequency images are statistic with image multivariate multiscale entropy, and the entropy ranges can be mapped into the particle size distribution. Three different size fraction images are used to verify the accuracy of the proposed method. The experimental results show that the validity and accuracy of our proposed model is better than other methods in multi-scenario ore particle size detection.

Effect of the Particle Size of Iron Ore on the Pyrolysis Kinetic Behaviour of Coal-Iron Ore Briquettes

High reactivity coke is beneficial for achieving low carbon emission blast furnace ironmaking. Therefore, the preparation of highly reactive ferro-coke has aroused widespread attention. However, the effects of the particle size of iron ore on the pyrolysis behaviour of a coal-iron ore briquette are still unclear. In this study, the effect of three particle sizes (0.50–1.00 mm, 0.25–0.50 mm and &lt;0.74 mm) of iron ore on the thermal and kinetic behaviours of coal-iron ore briquettes were investigated by non-isothermal kinetic analysis. The results showed that the synergistic effect of iron ore and coal during coking mainly occurred during the later reaction stage (850–1100 °C) and smaller particle sizes of iron ore have a stronger synergistic effect. The addition of iron ore had little effect on T0 (the initial temperature) and Tp (the temperature at the maximum conversion rate) of briquette pyrolysis, however itgreatly affected the conversion rate and Tf (the final temperature) of the briquettes. T0 decreased with the decrease of iron ore particle sizes, while Tp and Tf showed opposite trends. After adding iron ore into the coal briquette, the reaction kinetics at all stages of the coal-iron ore briquettes changed. The weighted apparent activation energy of the caking coal (JM) briquette was 35.532 kJ/mol, which is lower than that of the coal-iron ore briquettes (38.703–55.627 kJ/mol). In addition, the weighted apparent activation energy gradually increased with decreasing iron ore particle sizes.

Extraction of iron and aluminum from high-iron bauxite by ammonium sulfate roasting and water leaching

High iron content is one of the challenges in utilizing the refractory bauxites in China. An improved method for treating the high-iron bauxite by roasting with (NH4)2SO4 was proposed, which offers a possible alternative method for utilizing the high-iron bauxite. The influences of the roasting time, roasting temperature, material ratio, and ore particle size on the extraction ratios of Fe and Al were studied, and the orthogonal test was used to optimize the reaction conditions. The optimized reaction conditions were proposed as follows: roasting temperature of 450 °C, roasting time of 120 min, material ratio of (NH4)2SO4 to ore of 2.5:1.0, and ore particle size below 80 μm. The roasting mechanism and kinetic parameters including the apparent activation energy and reaction rate constant were investigated. The results showed that the control step of the roasting process was the internal diffusion on the product layer and the apparent activation energy was 19.22 kJ mol−1 in the reaction temperature range. The kinetic equation was obtained finally.

Fractal kinetic characteristics of hard-rock uranium leaching with sulfuric acid.

In order to study the fractal dynamic properties of uranium leach mining and discuss the influence of ore crushing on the dynamics of leach mining, uranium mine ore rocks in southern China were selected as the research object and an acid leaching experiment was performed on the ore samples with different fractal dimensions of 1.1, 1.4, 1.7, 2.0, 2.3 and 2.6. In the column leaching experiment, a PVC pipe with an inner diameter of 112 mm and a height of 1500 mm was used. The uranium content was determined by using titanium trioxide that was placed into a 0.1 mg ml−1 standard uranium solution, and a sampling rate of once daily with a 5 ml volume of leaching solution was adopted after 8 h drenching time. The results show that the flow rate of the leaching solution depends on the distribution of the ore's particle size, that is, a larger fractal dimension results in a smaller flow rate. The concentration of the uranium leaching solution reaches a maximum value which subsequently decreases with time on the third day of the experiment, and it seems that the changes in the uranium concentration tend to be stable at around 15 days. Moreover, the concentration seems to increase with the increasing fractal dimension, and the fractal dimension of the ore particle size has a significant impact on the leaching kinetics. When the fractal dimension is between 1.1 and 2.6, the uranium dissolution rate, K, increases with the increasing fractal dimension. The kinetic reaction of the uranium leaching is a liquid–solid one, which is controlled by chemical reactions in the earlier phase. While the middle reaction phase is mainly chemical-diffusion reaction coupling, and the latter part of the reaction is controlled by diffusion. As the fractal dimension increases, the liquid–solid reaction controlled by diffusion appears at earlier phases. When the fractal dimension is greater than 2.0, the time of entering the diffusion control phase only changed little with the increasing of the fractal dimension. At last, a fractal dimension of 2.0 is suggested for the acid leaching of uranium ore crushing.

Reductive recovery of manganese from low-grade manganese dioxide ore using toxic nitrocellulose acid wastewater as reductant

The hydrometallurgical strategy of extracting Mn from low-grade Mn ores has attracted attention for the production of electrolytic manganese metal (EMM). In this work, the reductive dissolution of low-grade MnO2 ores using toxic nitrocellulose acidic wastewater (NAW) as a reductant was investigated for the first time. Under the optimized conditions of an MnO2 ore dosage of 100 g·L−1, an ore particle size of −200 mesh, concentrated H2SO4-to-NAW volume ratio of 0.12, reaction temperature of 90°C, stirring speed at 160 r·min−1, and a contact time of 120 min, the reductive leaching efficiency of Mn and the total organic carbon (TOC) removal efficiency of NAW reached 97.4% and 98.5%, respectively. The residual TOC of 31.6 mg·L−1 did not adversely affect the preparation of EMM. The current process offers a feasible route for the concurrent realization of the reductive leaching of Mn and the treatment of toxic wastewater via a simple one-step process.

Reductive leaching of low-grade manganese oxide ores using pretreated straw as reductant

ABSTRACT The extraction of manganese from a low-grade manganese oxide ore was investigated in the presence of pretreated straw as reductant in sulfuric acid medium. It was found that concentrated sulfuric acid disrupted the structure of cellulose, hemicellulose and lignin of straw, making it possible to hydrolyse into monosaccharide. The effects of stirring speed, reductant/ore mass ratio, sulfuric acid concentration, ore particle size, leaching temperature and leaching time were examined. The optimal leaching conditions were determined as: stirring speed of 300 rpm, reductant/ore mass ratio of 0.3, sulfuric acid concentration of 9% (v/v), particle size of 45–75 μm and temperature of 85°C for 180 min. Under the above conditions, 92.8% manganese and 10.8% iron were extracted. The experimental results indicated that a high manganese leaching efficiency was achieved with a relatively low iron extraction.