查看更多>>摘要：Pentlandite is very important to the mining industry since it is the main source of metallic nickel. However, its separation from hexagonal pyrrhotite by froth flotation is challenging due to their similar floatabilities, and inefficiencies in this process generate environmental issues caused by emissions of sulfur oxide gases during the pyrometallurgy of nickel concentrates. Although successful, the current pyrrhotite depressant (diethylenetriamine - DETA) is also harmful to the environment which compels the research and development of non-toxic and biodegradable reagents such as polysaccharides. Therefore, three starch depressants for hexagonal pyrrhotite were used in this study. They include a paste starch with higher molecular weight (MW), a paste starch with lower molecular weight, and a crosslinked starch formed by mixing the lower MW paste starch and copper ions. We hypothesize that the presence of crosslinking additives such as copper provide a "driving" effect towards the gangue mineral. The performance of depressants was investigated in single and binary mineral systems. For single minerals, all depressants impacted hexagonal pyrrhotite and pentlandite flotation recovery. For the binary mineral systems, the higher MW paste starch and crosslinked starch showed an improved Ni separation efficiency of 90.5% and 85.6%, respectively, at an intermediate PIBX dosage (9.66x10-6 M) compared to the lower MW paste starch (58.6%), demonstrating a certain selectivity. The choice of the most suitable starch depressant proved to be complex since both minerals were able to chemically interact with the starch depressants as verified via X-ray photoelectron spectroscopy (XPS). Hydroxyl groups present on the alpha-D-glucose units bound with surface metal (Fe and/or Ni) hydroxylate species while the crosslinked starch also interacts with the mineral surfaces by electrostatic attraction. These findings will contribute to the advancement of knowledge related to the use of polysaccharides as depressants for complex sulfide mineral systems.
查看更多>>摘要：An industrial gas holdup sensor was designed, constructed, and its performance assessed on a 250 m3 self-aerated Wemco cell at Los Pelambres concentrator. The submersible sensor comprised a ceramic-liner IP68 magnetic flowmeter assembled to a stainless steel gas exclusion cell, which resembles an inverted truncated cone. The gas exclusion cell was designed to avoid low-velocity sections where particles could settle. When the sensor device is vertically immersed in an aerated pulp a continuous downward flow of pulp without bubbles is induced through it. A remotely installed processing unit converts the flow velocity signal , provided by the magnetic meter, into a gas holdup signal, by applying Bernoullis equation to the induced flow. The ideal velocity in the Bernoullis equation is obtained by multiplying the measured velocity and the discharge coefficient. The discharge coefficient was found to be fairly constant over a wide range of Reynolds numbers. Gas holdup measurements were compared against those obtained by sampling a fixed volume of aerated pulp using the J K Tech Air Holdup Probe. These tests were conducted on different days over nine months to allow for the pulp properties to change. Gas holdup changes in the flotation machine were achieved by restricting the air intake to the cell by placing a stainless steel cap on top of the air suction pipe. Short and long-term testing demonstrated the sensor capability to provide reliable and accurate continuous-time gas holdup measurements for industrial flotation machines.
查看更多>>摘要：Four kinds of ionic liquids (ILs) with different counterions were used as collectors to perform flotation tests for pure quartz and quartz-hematite mixed ore. Pure quartz flotation showed that all ILs had excellent collection performance, exceeding 95% of the quartz was floated below the concentration of 8*10- 5mol*L-1. All ILs showed much better collecting capacity than DDA. Mixed ore tests without inhibitor showed the best effect using imidazole ILs with chlorine ligands as collector, 61.9% grade iron ore was obtained from the 51% TFe quartz-hematite mixed ore, and the recovery rate was 94.54%. The flotation using starch inhibitor showed that imidazole-based ILs containing hexafluorophosphate ligands achieve the highest beneficiation efficiency. It obtains 64.86% iron concentrate and 86.07% recovery rate. In the tests with inhibitor, all four ILs performed better flotation effects than DDA. X-ray photoelectron spectroscopy (XPS) investigation was conducted of quartz that was treated by ILs and DDA, and adsorption analysis was performed based on N(1S) position, N/Si ratio and C(1S) peaks. Fourier transform infrared spectroscopy (FTIR) study was also conducted, and the adsorption of ILs and DDA was further analyzed by the appearance of new peaks and the shift of peaks in IR spectrum, Zeta potential study intuitively showed the adsorption difference between the four imidazole ILs and DDA. The flotation results were discussed together with XPS, IR and Zeta potential study. In conclusion the higher charge density on the overall semi-micelle of ILs caused greater collecting capacity than that of DDA, and weaker charge of single adsorption site caused greater selectively. And, it is believed that the counterions of ILs affect the floatation effect by affecting the formation process of the semi-micelle.
查看更多>>摘要：Beneficiation of niobium and titanium carbides from pyrochlore ore via carbothermic reduction followed by magnetic separation was investigated in this work. During carbothermic reduction, Nb, Ti and Fe oxides within the pyrochlore ore could be reduced into NbC, TiC and metallic iron, respectively. The carbides gather around and dissolve into the metallic iron grains, enabling the enrichment of niobium and titanium carbides by magnetic separation with the carrier of metallic iron. Under the optimal conditions: coke dosage of 6%, reducing temperature of 1400 degrees C and time of 120 min, a magnetic concentrate with 4.18% Nb, 4.60% Ti and 70.57% Fe can be obtained followed by wet magnetic separation. The corresponding recoveries of Nb, Ti and Fe were 70.5%, 59.8% and 92.6%, respectively.
查看更多>>摘要：Fungal leaching is a promising method for uranium extraction from its low-grade ores. Nevertheless, an efficient leaching process needs to be developed. Herein, we proposed a macroparticle-enhanced method by which millimetre-sized inert particles were added to a culture medium for a two-step fungal leaching process. The impact of the addition of glass bead macroparticles on Aspergillus niger morphology and subsequent uranium extraction were investigated. Pellet-type morphology was found to be favorable to uranium extraction, and bioore pellets with 4-5 mm diameters showed a high leaching efficiency. However, the morphology of A. niger was driven toward dispersed mycelia and uranium extraction decreased at 210 rpm. The maximum uranium extraction of 75.5% was achieved with glass beads (40 g/L, 0.5 mm) at 180 rpm, an increase of approximately 10% compared to the control without glass beads. Analyses of organic acids by ion chromatograph showed that at these conditions, the amount of citric acid and oxalic acid consumed for uranium dissolution was the greatest. The three dimensional (3D) structures of bio-ore pellets were characterized by nano-computed tomography (nano-CT), and they presented different structures under the conditions with and without glass beads. The effect of stress energy (SE) induced by the glass beads was evaluated by a mathematical model, which revealed that the proper amount of energy input would contribute to increased uranium extraction.
Merrill-Cifuentes, JavierCracknell, Matthew J.Escolme, Angela
18页
查看更多>>摘要：The value of rock characterisation, whether it is for mineral exploration, extraction, or concentration, lies in the ability to describe its composition and texture. In the past century, extensive technological developments have provided new opportunities to assess compositional properties, both geochemical and mineralogical, and at different scales: X-ray diffraction, X-ray fluorescence, inductively coupled plasma mass spectrometry, reflectance spectroscopy, etc. More recently, the advent of imaging characterisation techniques and high-performance computing power has enabled the assessment of mineral texture in a robust and quantitative manner. This study proposes and validates an end-user focused workflow for the identification of textural families in a large drill-core hyperspectral imagery dataset, based on a novel textural feature extraction method named Mineral CoOccurrence Probability Field (MCOPF). This workflow combines vintage image textural assessment methods with modern machine learning techniques for the automated unsupervised classification of textures within a drill core hyperspectral imagery dataset. The results demonstrate a meaningful and robust identification of rock textural families (clusters), enabling a wide range of applications in geology, mining, and metallurgy in the academic and industrial sectors.
查看更多>>摘要：Bubble size distribution (BSD) is a factor that is well known for influencing the performance of many industrial processes, such as froth flotation. The most commonly used method for measuring bubble size consists of pro-cessing photographs of the bubbles. However, the source code of the algorithms for performing the image processing has been seldom published. This article addresses the above by presenting a comprehensive open -source software for processing images of bubbles, allowing researchers to quantify BSD. This software -Bubble Analyser -includes a standard image processing algorithm that was tested against manually segmented images, showing errors under 5% in the calculation of the Sauter mean diameter, the most common descriptor of BSD. Additionally, Bubble Analyser has been designed to easily incorporate new segmentation algorithms developed by other researchers, in order to expand the software capabilities, allow for algorithm comparisons, and foster collaboration in research.
查看更多>>摘要：The dodecylbenzenesulfonate isopropanolamine (DBIA) as a collector was first adopted in ilmenite flotation in this study, and its effect on the surface properties of ilmenite and titanaugite was investigated by contact angle and zeta potential measurements, X-ray photoelectron spectroscopy (XPS) analysis, and atomic force microscopy (AFM) detection. The flotation results showed that ilmenite obtained a superior floatability after being treated by DBIA, and that was ascribed to the improvement of the surface hydrophobicity of ilmenite. The zeta potential analysis indicated that the adsorption of DBIA onto ilmenite was stronger than that onto titanaugite. In addition, XPS detection revealed that the DBIA chemisorbed on the surface of ilmenite through reacting with Fe3+ active site, while weakly physisorbed onto titanaugite surface. Furthermore, the adsorption difference of DBIA led to a thick hydrophobic layer onto ilmenite surface but a sparse on the surface of titanaugite, which was vividly evidenced by the scanning results of AFM.
查看更多>>摘要：The world is facing critical technological and environmental challenges in the production of basic materials in high demand, such as aluminium and silica, whose processes were developed long ago. New production routes, involving using alternative resources and innovative technological solutions, are needed to secure access to these base materials at a lower cost to the environment, in terms of waste and carbon footprint. The European project AlSiCal is currently investigatingan environmentally friendly multi-step process for producing alumina and silica from anorthosite, an abundant feldspar mineral. The present paper focuses on the modelling strategy of the dissolution of anorthosite in concentrated hydrochloric acid, which is the first step of the AlSiCal process. The objectives of this study are (i) to give a reliable first-level prediction of the product speciation in the aqueous and solid phases, (ii) to provide the sensitivity of the process to key operating variables, and finally, (iii) to evaluate the performance of both batch and continuous leaching processes. The proposed methodology is based on the coupling of geochemical equilibrium simulations and particle reaction models, using different computational tools and relevant literature data. This makes it possible to select the favourable operation window and process configuration for the quantitative extraction of aluminium in solution and the production of amorphous silica with an acceptable purity for large-market applications.
查看更多>>摘要：Recent investigations suggest that ethylene glycol (EG) performs two important functions in the oxidative dissolution of chalcopyrite with hydrogen peroxide: it prevents H2O2 dismutation on the chalcopyrite surface and, secondly, it hinders H2O2 decomposition due to the presence of dissolved copper and iron in the leach liquor. Of these two, retarding the H2O2 breakdown probably contributes most to the observed improvement in copper leaching; however, the nature of the role that EG plays in the solution is unclear. For that reason, a systematic study was undertaken, at different concentrations of sulfuric acid and EG, to reveal the role of EG in the leaching process. The results of this investigation show that EG hinders H2O2 degradation by decreasing the copper and iron activities in the solution through Cu (II)-EG and Fe (II, III)-EG complex formation. Likewise, the slowing effect strongly depends on the H2SO4 concentration because the Fenton reaction, which is responsible for the decomposition, increases its efficiency with lower acid concentrations (< 0.1 M). Thus, successful leaching could be attained with concentrations above 0.7 M and 0.1 M of sulfuric acid and EG, respectively; otherwise, rapid H2O2 degradation and simultaneous EG mineralization (complete oxidation, in other words, oxidation to CO2 and H2O) are favored as a consequence of the reactions between H2O2 and the leached metals and the OH* radicals produced in the leach liquor, respectively. In view of these results, a brief discussion is presented on the implications of chalcopyrite leaching with H2O2, showing alternatives to increase its performance.
NSTL
Elsevier