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Minerals Engineering
Pergamon Press, Inc.,
Minerals Engineering

Pergamon Press, Inc.,

0892-6875

Minerals Engineering/Journal Minerals EngineeringSCIISTPEI
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    Utilization of gellan gum as a novel eco-friendly depressant in the flotation separation of fluorite from barite

    Wang, LongLyu, WeijianHuang, LingyunLi, Fuping...
    11页
    查看更多>>摘要：The relatively similar physicochemical features and floatabilities of fluorite and barite in the flotation process make the separation of these two minerals rather difficult. Exploration and utilization of efficient depressants is vital to improve the flotation separation performance. In this study, gellan gum (GG) was adopted as the depressant in the flotation separation of fluorite and barite with sodium oleate (NaOL) as collector for the first time. The inhibitory impact of gellan gum on the flotation performances of these two minerals was evaluated via flotation tests. The potential inhibiting mechanism of GG was systematically revealed via series of surface analytical measurements. Flotation experiments indicated that GG exhibited strong depressing effect on the barite flotation, whilst it showed little impact on the fluorite flotation. Zeta potential tests and surface wettability analyses demonstrated that GG intensely adhered onto barite and strongly prevented the subsequent NaOL adsorption, while it barely affected the NaOL adsorption onto fluorite. Adsorption capacity measurements confirmed that much higher amount of GG adsorbed onto barite than fluorite. Fourier transform infrared (FTIR) spectroscopy analyses and X-ray photoelectron spectroscopy (XPS) results implied that the quite weak physisorption of GG on the fluorite surface occurred, whereas strong chemical adhesion of GG occurred between GG and barite, which resulted in completely disparate flotation behaviors of these two minerals. As a result, selectively depression of barite flotation and the flotation separation of fluorite from barite were achieved. Therefore, GG can be used as an efficient and eco-friendly depressant to realize the flotation separation of fluorite and barite.
      原文链接:
    • NSTL
    • Elsevier

    Joint recovery of graphite and lithium metal oxides from spent lithium-ion batteries using froth flotation and investigation on process water re-use

    Salces, Aliza MarieBremerstein, IrinaRudolph, MartinVanderbruggen, Anna...
    8页
    查看更多>>摘要：Spent lithium-ion batteries (LIBs) contain critical raw materials that need to be recovered and recirculated into the battery supply chain. This work proposes the joint recovery of graphite and lithium metal oxides (LMOs) from pyrolyzed black mass of spent LIBs using froth flotation. Since flotation is a water-intensive process, the quality of the aqueous phase directly impacts its performance. In pursuit of an improved water-management strategy, the effect of process water recirculation on black mass flotation is also investigated. The fine fraction (<90 mu m) of the black mass from pyrolyzed and crushed spent LIBs was used. After flotation, 85% of the graphite in the overflow product and 80% of the LMOs in the underflow product were recovered. After flotation with 8 wt% solids, the process water contained about 1,000 mg/L Li and accumulated up to 2,600 mg/L Li after three cycles. The flotation with process water showed no significant impact on the recovery and grade of flotation products, suggesting the feasibility of water recirculation in black mass flotation.
      原文链接:
    • NSTL
    • Elsevier

    The differential effect of amorphous ?-S and orthorhombic a-S-8 on chalcopyrite bioleaching by Acidithiobacillus ferrooxidans

    Zheng, Xing-fuXia, Jin-lanLiu, Hong-changNie, Zhen-yuan...
    12页
    查看更多>>摘要：Elemental sulfur (S0), as one of the most important intermediates formed during chalcopyrite bioleaching, can exist in a variety of allotropic forms, among which amorphous mu-S and orthorhombic a-S8 are the most common forms. Although previous studies have focused on the effect of S0 on chalcopyrite bioleaching, how S0 allotropes affect chalcopyrite bioleaching is unclear. Therefore, in this work, the differential effect of a-S8 and mu-S on chalcopyrite bioleaching by Acidithiobacillus ferrooxidans (A. ferrooxidans) was studied at the molecular and atomic levels by combining synchrotron radiation-based X-ray absorption near edge structure (XANES) spectroscopy, comparative transcriptome analysis and density functional theory (DFT) calculations, accompanied by the determination of solution behaviors and mineral surface morphologies. The results showed that mu-S was favorable for bacterial adsorption and that the addition of mu-S could promote the copper extraction rates by A. ferrooxidans, while the addition of a-S8 inhibited the copper extraction rates. The XANES results showed that both cases with the addition of a-S8 and mu-S could affect the formation and evolution of secondary minerals during bioleaching by A. ferrooxidans. The comparative transcriptome analysis showed that the gene expression of A. ferrooxidans was much more affected by the addition of mu-S, with more genes upregulated than a-S8. The DFT results indicated that both a-S8 and mu-S could adsorb on the CuFeS2 (001) surface easily, and mu-S could make the CuFeS2 surface obviously change, while a-S8 hindered the adsorption of bacterial cells. Of note, mu-S could enhance the interaction between the CuFeS2 (001) surface and bacterial cells with stronger bonding and more transferred electrons than a-S8.
      原文链接:
    • NSTL
    • Elsevier

    Improvement of dynamic foam stability with low-frequency acoustic sound

    Ng, Chun YongYang, BingyuPark, HangilWang, Liguang...
    7页
    查看更多>>摘要：Exposing the froth phase of a flotation system to low-frequency acoustic sound was reported to improve the process efficiency, which was thought to be due to the improvement in the froth stability. However, no direct evidence of the stabilization effect of sound on froths or foams is available to date. The present work aims to resolve this issue by experimentally studying the effect of low-frequency acoustic sound on the stability of a foam, the two-phase counterpart of flotation froth, across a wide range of experimental conditions. Three different setups consisting of a flotation column or a bottom-driven mechanical flotation cell, with the foam being exposed to sound from above or below, were tested. The equilibrium height of the foam with a given flow rate of air supply was measured at steady state using the Bikerman's method. The equilibrium foam height was found to increase within certain ranges of sound frequencies and amplitudes, and at various surfactant concentrations (3-50 ppm) and superficial gas velocities (0.3-2.0 cm.s(-1)). An increase in sound amplitude or superficial gas velocities was also found to broaden the range of sound frequency that led to the stabilization effect. These findings were largely common for the three different setups tested, suggesting that this is a versatile method for improving the stability of foams. A strong correlation was also found between the stabilization of foam demonstrated in the present work and the stabilization of froth reported in a previous study, implying that the stabilization mechanisms could be similar.
      原文链接:
    • NSTL
    • Elsevier

    Recovery of fine gold loss to tailings using advanced reactor pneumatic flotation Imhoflot (TM)

    Duong Huu HoangImhof, RainerSambrook, TimBakulin, Alexander E....
    12页
    查看更多>>摘要：Gold concentration usually consists of gravity separation and froth flotation. However, flotation faces difficulties due to gold-bearing ores often being refractory and finely disseminated in nature. Poor recovery and low flotation kinetics of fine particles are mainly due to the low frequencies of particle-bubble collisions and an increase in entrainment of fine gangue particles decreases the grade. In this study, applications of two pilot Imhoflot (TM) G-14 (tangential feed to the separator vessel with 1.4 m diameter) cells in an open circuit demonstrated its ability to recover fines with high gold grade and achieved a high recovery of 65-68 % for the particle size fraction of -20 mu m. The gold content in the -20 mu m fraction of tailings is only about 0.36 g/t, which is lower than in the existing flotation circuit (0.47 g/t), including rougher and scavenger banks. Furthermore, bubble size measurements indicate that pneumatic Imhoflot (TM) generated very fine bubbles in a high shear environment, improving particle-bubble collision frequencies.
      原文链接:
    • NSTL
    • Elsevier

    Optimization of combined mechanical activation-leaching parameters of low-grade ?-spodumene/NaF mixture using response surface methodology

    Rosales, Gustavo D.Resentera, Alexander C. J.Wuilloud, Rodolfo G.Rodriguez, Mario H....
    9页
    查看更多>>摘要：This paper studied the optimization of the Li extraction process by mechanical activation of low-grade alpha-spodumene ore with NaF followed by leaching with NaF/H2SO4 solution at low temperatures (<= 90 degrees C). The effects of mechanical activation on the structural and microstructural parameters (crystallite size and lattice strain) of the mineral/NaF mixture were analyzed. In addition, the investigated operating parameters were mechanical activation time, reaction temperature, and leaching time. The response surface methodology based on a D-optimal design was used to comprehend the effect of the process parameters on the leaching efficiency of Li. The results indicated that the milling time, the temperature, and the leaching time had a positive effect on the lithium extraction. The temperature, the leaching time, and their interaction had the greatest effect on the lithium extraction. The optimum Li extraction value achieved was 81% working with a sample activated 600 min, and a temperature and leaching time of 90 degrees C and 240 min, respectively. The characterization of the products showed that Al and Si were recovered as Na3AlF6 and Na2SiF6 during the leaching process. The presence of albite and quartz indicated that the leaching reaction was highly selective on alpha-spodumene, allowing to work with mineral samples with low Li content.
      原文链接:
    • NSTL
    • Elsevier

    A review on steeply inclined settlers for water clarification

    Reyes, CristianApaz, FernandoNino, YarkoBarraza, Belen...
    18页
    查看更多>>摘要：Steeply inclined settlers (SIS) are solid-liquid separators that feature close, inclined confining elements that allow significant settling enhancement when compared to vertical tanks, resulting in relatively low footprints at equal throughput. The present article reviews the working principle, flow configuration, capacity, and several technological advances related to this kind of equipment. The consistency of the Ponder, Nakamura and Kuroda theory, developed after the discovery of the Boycott effect in 1920, which is essential to the settling enhancement effect, and the engineering approach developed independently for the design of SIS settlers during the late 1960's, based on particle trajectory analysis, is established. A discussion about potential developments for future improvement of the technology is made, with emphasis on three main topical areas: improvements of settling element array, optimization of inlet conditions, and potential improvements of the design of settling elements. The application of the technology to the mining industry is discussed in the context of increasing water scarcity and the progressive ore grade decrease.
      原文链接:
    • NSTL
    • Elsevier

    Process flowsheet for extraction of Fe, Al, Ti, Sc, and Ga values from red mud

    Agrawal, ShreyDhawan, Nikhil
    12页
    查看更多>>摘要：A comprehensive process flowsheet is investigated to recover metallic values from red mud with high-purity products such as alumina, silica, ferrous oxalate, titania, and Sc-Ga containing purified solution. The carbonated red mud leached in 1 M hydrochloric acid at 50 degrees C for 1 h dissolves 44.5% Al and 51% Si, followed by 2 M oxalic acid leaching at 90 degrees C for 2.5 h yielding 61% Fe and 46-48% Sc and Ga dissolution. High-purity ferrous oxalate product is retrieved from the leach solution, and the Sc and Ga ions report to the solution. Titanium enriched residue is baked with 1 mL/g sulfuric acid at 300 degrees C for 1 h, forming TiOSO4, Fe-2(SO4)(3), and Al-2(SO4)(3) phases, followed by water leaching. 64.5% Ti and similar to 27% Fe dissolution is attained, and solution contains Fe (7.47 g/L), Ti (3.09 g/L), Al (2.44 g/L), Si (0.17 g/L), Sc (2 mg/L), and Ga (3 mg/L) ions. Thermal hydrolysis of solution recovers titania precipitate (96.9% purity), and the solution after hydrolysis contains Fe, Sc, and Ga values. The overall metal extraction (84% Fe, 79% Ti, 92% Al, 78% Sc, 89 % Ga) in the proposed flowsheet is higher compared to direct acid baking process (51% Fe, 65% Ti, 89% Al, 51% Sc, 48 % Ga). Products recovered include high-purity silica (4.8 wt%), alumina (9.3 wt%), Fe(II) oxalate (20.7 wt%), titania (8.9 wt%), and a final residue yield of 12.6 wt%. Microwave exposure at 2 kW for 7 min improves the dissolution of the Sc (84%) and Ti (85.5%). H-2 reduction at 450 degrees C, 30 min converted hematite to magnetite and increased Fe dissolution to 90%. Red mud's mineralogical and composition modification by magnetic separation, reduction, and microwave exposure were ineffective to improve selective dissolution.
      原文链接:
    • NSTL
    • Elsevier