查看更多>>摘要：? 2022 Elsevier LtdMineral processing plant performance depends on multiple factors, including the feed and the parameters to control the process. In this work, we show how to assess plant performance using geometallurgical modeling and dynamic simulation. Several models that describe comminution, classification, flotation, and residence time distribution (RTD) are implemented as modules and then connected to represent generic plant configurations. The estimation of the RTD is used to assess the ore blending generated within the plant through a methodology based on weighting the ore contribution at the plant discharge. Additionally, the RTD is used to display the ore permanence at different plant stages, which can be used as an operational input to anticipate the consequences of a perturbation in the feed. Different simulation scenarios are tested using synthetic data, including different plant configurations, time support for blending assessment, and ore feeding sequence. The results show that the simulation is sensitive to these attributes. Significant differences are detected in the generated product compositions when the plant configuration is changed. Also, distinct mine plans can be evaluated through simulation, predicting their processing performance. Therefore, the simulation tool developed can be used to evaluate real mineral processing operations and to test different operative strategies.
查看更多>>摘要：? 2022This study assessed the technical feasibility of using biofuels as renewable reductants in the production of synthetic rutile (88–95% TiO2) from ilmenite (FeTiO3) by the Becher process. Three biofuels were evaluated—charcoal (CC), wood kindling (WK) and gum tree sticks (GTS)—for the quality of the synthetic rutile products that were produced from a representative ilmenite sample and compared with that of a Western Australian coal (WAC), which is typical of coals that are being used in this technology. The results show that the carbon content of the different reductants ranged from 46% each for GTS and WK to 82% for CC, compared with 58% for WAC. The renewable reductants yielded synthetic rutile products with TiO2 content between 93% for GTS and 95% each for CC and WK, compared with 94% for WAC. The iodine numbers of carbon residues from the reduction process were 900 each for WK, CC and GTS, while that of WAC was 700. Overall, these results indicate that biofuels could be alternatives to coal in the production of synthetic rutile from ilmenite.
查看更多>>摘要：? 2022 Elsevier LtdThe removal of heavy metals, especially cadmium, from wet phosphoric acid is still a challenging stage during the manufacturing of phosphate fertilizers. In this work, a novel approach was developed to improve the performance of the sulfide precipitation process as a purification technique. This is based on NaHS rather than Na2S as a precipitating agent in both batch and continuous modes for cadmium removal from synthetic wet phosphoric acid. First, the respective performance of Na2S and NaHS was compared in the batch mode. NaHS was shown to improve decadmiation in comparison to Na2S even though the same trends were observed for both precipitating agents as a function of operating conditions. An increase in Sulfur/Cd2+ molar ratio improved cadmium sulfide precipitation. Conversely, increasing temperature and phosphoric acid concentration impaired the effectiveness of cadmium removal efficiency. An apparent kinetic model was developed taking into consideration the reaction mechanisms and supersaturation to predict the residual cadmium concentration in phosphoric acid solutions. The feasibility of the continuous process based on NaHS was also assessed. The results showed that a residence time of 40 min was needed to achieve 85.6 % of Cd2+ elimination at 25 °C. As aggregation seemed to be the main mechanism governing particle size, this increased with the Sulfur/Cd2+ ratio, which could improve downstream solid separation. Eventually, these findings of this study provide useful insights into the feasibility of chemical precipitation using NaHS as a technology of phosphoric acid decadmiation in the industry.
查看更多>>摘要：? 2022 Elsevier LtdThis study is focused on the development of iridium(IV)-specific quaternary diammonium cations containing electron-donating and electron-withdrawing groups. Quaternary diammonium cations used were tetramethylbenzyl-1,10-diammonium decane chloride (QuatDMDAMeBnz), tetrabenzyl-1,10-diammonium decane chloride (QuatDMDABnz), tetratrifluoromethylbenzyl-1,10-diammonium chloride (QuatDMDACF3Bnz), and tetranitrobenzyl-1,10-diammonium chloride (QuatDMDANO2Bnz). Polyvinylbenzylchloride (PVBC) nanofibers were used as a support material, and the functionalised nanofibers were used for the separation of Ir(IV) from Rh(III). The efficiency of the quaternary diammonium cations was investigated in a column study under dynamic flow adsorption conditions. Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibers functionalized with diammonium cations showed [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- on the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (3.08 mg/g; 16.01 mmol/g) < F-QuatDMDABnz (3.39 mg/g; 17.63 mmol/g) < F-QuatDMDACF3Bnz (5.46 mg/g; 28.42 mmol/g) < F-QuatDMDANO2Bnz (7.10 mg/g; 36.96 mmol/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibers increased with an increase in the electron-withdrawing nature of the substituent on the quaternizing group. This trend was further explained by considering the anion binding energies and electrostatic charges of the diammonium cations as well as their ion-pairing interactions with [IrCl6]2- and [RhCl5(H2O)]2- using molecular modeling calculations. The formation of [(L)IrCl6] ion-pairs with the charge diffuse [IrCl6]2- anion was energetically favoured from QuatDMDAMeBnz to QuatDMDANO2Bnz. The positive electrostatic potential (ESP) values of 473.92 kcal/mol for QuatDMDAMeBnz, 495.85 kcal/mol for QuatDMDABnz, 991.12 kcal/mol for QuatDMDACF3Bnz and 1133.05 kcal/mol for QuatDMDANO2Bnz also followed this trend. This trend was also well correlated with binding energies of the respective cations with [IrCl6]2- which were 22.66 kcal/mol for QuatDMDAMeBnz, 27.43 kcal/mol for QuatDMDABnz, 49.19 kcal/mol for QuatDMDACF3Bnz and 51.04 kcal/mol for QuatDMDANO2Bnz.
查看更多>>摘要：? 2022 Elsevier LtdIn the United States, sandstone-hosted ore deposits of the Paradox Basin (Colorado Plateau) are major resources of uranium and vanadium, two metals important to green energy among other applications. Despite historic and current mining interest, and their significance as major domestic resources of critical elements, the geometallurgy of these deposits has received little study. This article documents the geometallurgy and process mineralogy of the U-V ores and identifies the principal barriers to optimal recovery by acid leaching. Most of the metals occur as pitchblende (mixed uranium oxide-silicate), V-hydroxides, V-bearing phyllosilicates, and diverse vanadates of U, Pb, Cu, and other metals. Commercial extraction is by two-stage heated tank leaching with H2SO4 and NaClO3, yielding high U but lower V recovery (70–75% in the industrial operation). Laboratory leaching experiments coupled with comparisons of head and residue mineralogy indicate that the unrecovered U consists of micron-scale pitchblende grains locked within quartz and other insoluble minerals. The principal cause of suboptimal V recovery is the V-phyllosilicates, which show variable but generally poor solubility at room temperatures. An ancillary cause is locking of a small amount of fine-grained V-hydroxide and pitchblende by authigenic quartz and V-phyllosilicates. Comparison with other global V resources suggests that variable solubility of V-phyllosilicate ore minerals may also diminish recovery from more common ore deposit types, such as V hosted in black shales or stone coal, particularly in heap leaching of low-grade ores at coarse grain sizes.
查看更多>>摘要：? 2022 Elsevier LtdA new random packed agitation column was presented to enhance the evaluation of dispersed phase holdup and hydrodynamic velocities. The extraction of cobalt ions from an aqueous to organic phase was observed under operating conditions. The interaction and association between operating parameters (rotor speed, aqueous phase flow rate (Qc), and organic phase flow rate (Qd)) were investigated by designing response surface methodology (RSM). Quadratic models for three responses (holdup (φ), slip velocity (Vs), and extraction efficiency (%E)) were obtained by statistical analysis. The achieved optimal conditions included 203 rpm of rotor speed, 32 L/h of Qd and 28 L/h of Qc. The model outcomes were 0.094, 10.57 mm/s, and 99.91% for φ, Vs, and %E, respectively. Comparison between results obtained from the central composite design approach and artificial neural network (ANN) proved that both techniques had a high ability to predict the experimental data, but the ANN technique had a higher coefficient of determination (0.9999) and lower error. The cobalt recovery can be significantly increased using higher rotor speed and phase flow rates. The data clearly demonstrates that the column configuration can be applied with high efficiency for the recovery of cobalt ions or other elements from secondary sources.
Vaziri Hassas B.Shekarian Y.Rezaee M.Pisupati S.V....
12页
查看更多>>摘要：? 2022Rare earth elements (REEs) and critical elements (CEs) have been in the spotlight recently due to their vital role in high-tech applications and green energy initiatives. Due to the scarcity of mineral resources for the majority of these elements, there has been significant interest in the recovery of these elements from secondary resources. Among the secondary resources, acid mine drainage (AMD) and associated sludge materials have been found to be viable sources of multiple critical elements, including REEs, Al, Co, and Mn. AMD and sludge samples from 3 AMD treatment sites in Pennsylvania were characterized for elemental content and contained value evaluation. A novel purification process based on a previously developed 3-stage AMD treatment process was designed to recover high-grade Al, REE, Co, and Mn products from the sludge materials through aqueous processing with multiple cleaner steps and precise control of the process parameters. The final products of the three stages of this purification process are boehmite and dawsonite in Stage I, adamsite-(REE) in Stage II, and cobalt oxide and ramsdellite in Stage III. Recoveries of > 99 % for the target elements were achieved with the design of a recycling load. Through the proposed purification process, 92.8 % aluminum minerals in Stage I, 88.5 % mixed-REE-carbonate in Stage II, 68 % ramsdellite, and 6.9 % cobalt oxide in Stage III were produced.
查看更多>>摘要：? 2022 Elsevier LtdThis paper describes a 3D cellular automaton (CA) for modelling ore pile formation that incorporates size segregation due to surface stratification. Ore stockpiles and bins are essential in mining operations as a buffer between the mine and the mineral processing plant, and their operation plays an important role in the overall performance of the downstream equipment. Size segregation can occur if the feed size to the pile varies over time or due to a variety of segregation mechanisms occurring in the pile itself. In particular,it can occur as a result of percolation stratification within surface flows. The structure of the newly developed CA model is described, and the simulated surface profile and size segregation response is validated through a series of laboratory-scale piles for characterizing the segregation potential of the feed particles. It is found that the model adequately describes the segregation behaviour at a range of model scales where coarse particles roll to the outside of the pile and fine particles are concentrated around the centre of the pile. Moreover, it is found that the model is sufficiently fast to use in real-time applications such as dynamic process control and digital twins.
查看更多>>摘要：? 2022The selective flotation separation of pyrite and chalcopyrite, and the comprehensive utilization of AMD play a vital role in the cleaner production of copper sulfide ore. In this paper, flotation separation of chalcopyrite and pyrite via Fenton oxidation modification in a low alkaline acid mine drainage (AMD) system was investigated. The results of micro-flotation experiment displayed that the maximum recovery difference between chalcopyrite and pyrite was 74.6% at recommended test conditions. The artificial mixed-mineral flotation experiment further confirmed the desirable flotation separation of minerals. Zeta potential, FTIR spectra analysis, contact angle measurement and adsorption amount analysis results confirmed that the hydrophilic species caused by Fenton oxidation could seriously hinder the interaction between pyrite surfaces and EX collector. Whereas, the Fenton oxidation had feeble influence on the floatability of chalcopyrite. The XPS study indicated that Fenton oxidation significantly increased the contents of SO42- on pyrite surfaces, and the concentration of SO42- increased from 5.9% to 37.65%. Meanwhile, this modification promoted the deep transformation of Fe chemical states mainly from Fe(Ⅱ)-S to Fe(III)–OOH and Fe2(SO4)3. As a result, the contents of Fe(III)–OOH and Fe2(SO4)3 reached 50.04% and 29.19%, respectively. For chalcopyrite, a small amount of oxide/hydroxide species were formed during this processing, and the chalcopyrite can interact with EX collector effectively. Thus, flotation separation of chalcopyrite and pyrite via Fenton oxidation modification in a low alkaline AMD system mainly attributes to the significant differences in the number and species of hydrophilic species.
查看更多>>摘要：? 2022 Elsevier LtdLithium-ion industry requires high amounts of lithium in high purity and spodumene, together with brine, are the major sources. Spodumene has three polymorphic forms, the one occurring in nature is α-spodumene. This form is highly resistant to chemical attack due to its compact structure containing silicon and aluminium oxides. Chemical analysis of this material is usually performed by combining fusion followed by acid digestion. However, microwave radiation converts α-spodumene to β-spodumene and it is known that this latter form can be chemically attacked using less critical reaction conditions. Based on this behaviour, it was developed a microwave-assisted procedure for chemical analysis of α-spodumene aiming the determination of lithium and other metals of interest by using an acid mixture composed by sulphuric and phosphoric acids and diluted hydrofluoric acid solution. The feasibility of using ammonium fluoride, a less critical reagent, instead of HF was also demonstrated. The heating program was implemented in 60 min at a maximum temperature of 230 °C using closed vessels for digestion of α-spodumene. All elements were determined by inductively coupled plasma optical emission spectrometry.
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