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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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    Performance assessment of an innovative precise low-intensity magnetic separator

    Wang F.Dai H.Tong X.Zhang S....
    8页
    查看更多>>摘要：? 2022 Elsevier LtdAn innovative precise low-intensity magnetic separator (PLIMS) was developed for recovering low-grade magnetite. The effects of the key parameters on the separation performance of the PLIMS in recovering magnetite were investigated. The results indicated that the drum rotation speed and feed particle size played major roles in enhancing the grade of the concentrate and the recovery. Additionally, the performances of the PLIMS and selected conventional low-intensity drum magnetic separators (CLIMSs) and Davis tube testers (DTTs) were compared. The comparison revealed that the performance of the PLIMS was consistent with that of the DTT in terms of the grade of the concentrate and the recovery. In addition, the PLIMS had a higher iron grade with fewer gangue particles and higher recovery compared with the CLIMS. For the PLIMS, the remnant flux density of the magnet assembly was designed to gradually increase from low to high along the flow direction of the slurry. In the entire magnetic separation process, the magnetic force acting on the captured magnetic particles is always the most minor magnetic force required to achieve precise magnetic separation, which results in improved selectivity. Furthermore, the advantage of the PLIMS is that seven concentrates can be obtained by one magnetic separation. Therefore, the newly developed PLIMS simplifies the magnetic separation process and produces multiple products, and the grade of the concentrate can be flexibly controlled. It has a high recovery and can create various high-, medium-, and low-grade concentrates.
      原文链接:
    • NSTL
    • Elsevier

    The role of sodium phytate in the flotation separation of smithsonite from calcite

    Wang L.Lyu W.Zhou W.Zhang H....
    10页
    查看更多>>摘要：? 2022 Elsevier LtdThe effective flotation separation of smithsonite and calcite has always been a thorny problem due to their relatively similar physicochemical property. Developing efficient and selective depressant is the key to address this obstacle. In this study, sodium phytate (SP) was introduced as a novel depressor for high-efficient flotation separation of smithsonite and calcite. Influences in flotation performances induced by SP and its possible underlying mechanism were thoroughly studied by various advanced detection techniques. Flotation tests indicated that calcite flotation was significantly depressed, whereas the smithsonite flotation was barely affected. Zeta potential analysis showed that SP adsorbed stronger on calcite than smithsonite. Furthermore, the SP adsorption exhibited little influence on the subsequent sodium oleate (NaOl) adsorption onto smithsonite, whereas it strongly hindered the NaOl adsorption on the calcite surface. Fourier transform infrared (FTIR) measurement and X-ray photoelectron spectroscopy (XPS) analysis further unveiled that SP weakly adsorbed on the smithsonite surface through electrostatic attraction that did not interfered the subsequent NaOl adsorption, whereas SP chemically adsorbed on the calcite surface strongly which greatly blocked the following adsorption of NaOl on the calcite surface. As a result, the calcite flotation was selectively depressed and the flotation separation of smithsonite from calcite was eventually achieved.
      原文链接:
    • NSTL
    • Elsevier

    Efficient extraction of nickel from sintered alloy by stepwise leaching: Thermodynamic and kinetic studies

    Han J.Wang Y.Qin W.Mao X....
    13页
    查看更多>>摘要：? 2022 Elsevier LtdAtmospheric acid leaching is widely used to extract nickel from secondary resources due to its mild effect, but the extraction efficiency of nickel still remains limited. In this work, a sulfuric acid curing process was developed to improve the extraction of nickel by treating the leaching residues after acid leaching. The factors influencing the extraction of nickel from sintered alloy have been systematically studied based on thermodynamic calculations. The results show that the extraction of nickel reached 80.34 % after acid leaching under the optimized conditions. Reaction kinetic studies indicate that the leaching process was governed by a combination of the mixed control model (0–60 min) and the surface chemical reaction control model (60–100 min), with the apparent activation energies of these two stages determined as 33.32 and 67.07 kJ/mol, respectively. The X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS) analyses indicate that the NiO coated by Ni2O3 in the sintered alloy and NiO passivation films generated during the acid leaching process hindered further dissolution of metallic nickel. The nickel oxides and passivation films could be transformed into water-soluble NiSO4 after sulfuric acid curing with 60 % H2SO4 solution at 140 ℃. The overall extraction efficiency of nickel can reach as high as 99.13 % by using the two-stage leaching developed. This work provides a feasible and highly efficient approach to extract nickel from sintered alloy.
      原文链接:
    • NSTL
    • Elsevier

    Selective sulfate sorption from boric acid factory process liquor: Chitosan-bentonite biocomposite film synthesis as sorbent

    Kaya F.Ozer A.
    15页
    查看更多>>摘要：? 2022 Elsevier LtdChitosan is a natural polymer that is renewable, biocompatible, and biodegradable. Bentonite is a natural mineral with low environmental effects. For this reason, chitosan- bentonite biocomposite film was synthesized as a sorbent and its characterized by FT-IR, SEM, EDX, CHNS elemental analysis and thermal analysis techniques. The sorbent was utilized for selective sulfate (SO42?) sorption from boric acid factory process liquor, because one of the most important problems in the boric acid production process is sulfate impurity. The sulfate sorption capacity in the acidic region (pH < 5) was determined as 308.38 mg/g and the equilibrium time was determined as 10 min. It has also been found that the sorbent is regenerative and reusable. Sulfate sorption took place by means of primary amine (-NH2) groups in the structure of the biocomposite. In addition, it was considered that the synthesized sorbent acts as a weakly basic anion exchanger resin. It was determined that the total sulfate salt concentration in the process liquor medium decreased by approximately 30.36% depending on the sulfate sorption. In this context, it is considered that the boric acid factory process liquor has been successfully purified.
      原文链接:
    • NSTL
    • Elsevier

    Validation of a dynamic non-linear grinding circuit model for process control

    le Roux J.D.Steyn C.W.
    10页
    查看更多>>摘要：? 2022 Elsevier LtdA step-wise algebraic routine is used to fit a dynamic non-linear model, specifically developed for process control, to steady-state process data of an industrial single-stage grinding mill circuit. Step-test data from the industrial plant is used to validate the response of the non-linear model. The results indicate that the model provides a qualitatively accurate response of the main process variables. Because the non-linear model parameters can be calculated from steady-state data, it provides an advantage over classical system identification methods as it does not require an expensive and disruptive step-test campaign to develop linear transfer function models. The model is ideal for model-based predictive process control.
      原文链接:
    • NSTL
    • Elsevier

    Feed hardness and acoustic emissions of autogenous/semi-autogenous (AG/SAG) mills

    Owusu K.B.Skinner W.Asamoah R.
    15页
    查看更多>>摘要：? 2022 Elsevier LtdIn this study, the relationship between acoustic emissions and hardness of different rock types (model quartz, model calcite, and real iron ore) coupled with binary mix ratios of model quartz and iron ore (1:3, 1:1 and 3:1) was investigated in a laboratory-based AG/SAG mill. The acoustic emission response and sensitivity of the mill were compared, along with its product particle size distribution. Features, such as discrete wavelet transform (DWT), power spectral density estimate (PSDE), and statistical root mean square (RMS) were extracted from the mill acoustic emissions. From the results, it was evident that the mill acoustic emission response can be used to classify different rock hardness and their binary mixtures. Model quartz emitted the highest acoustic response, followed by iron ore and model calcite at the initial stages of grinding (5 min). The results further indicated that as the rock feed sizes reduced, the average mill noise also increased as a function of grinding time. Accordingly, the acoustic emission presented a contrasting effect with model calcite and model quartz emitting the highest and lowest noise emission, respectively. The proportions of different mineral types (model quartz and iron ore) were reflected well in the acoustic emissions. The study has demonstrated that the integration of acoustic sensing techniques in AG/SAG mills can serve as a proxy for online measurement of different rock/ore hardness, for example, as a fast track method to determine the hardness of ores in comparison to the traditional ore grindability procedures, such as Bond work index (BWI) and SAG power index(SPI) tests which can be laborious and time-consuming.
      原文链接:
    • NSTL
    • Elsevier

    Activation mechanism of diasporic bauxite calcined with sodium carbonate

    Sun Y.Pan A.Li K.Hu S....
    11页
    查看更多>>摘要：? 2022 Elsevier LtdA series of sodium aluminosilicates (Na2-xAl2-xSixO4, x = 0.85, 0.55, 0.45, 0.35, 0.25 and 0.05) can be generated in the soda sintering process, some of which can be dissolved in sodium aluminate solution. This paper focuses on the transformation of aluminum-bearing minerals into Na2-xAl2-xSixO4 during the calcination of diasporic bauxite with different proportions of Na2CO3 at 400–1100 °C. Based on thermodynamic analysis, the thermal behaviors, phase transformations and bonding changes of the aluminum-bearing minerals are investigated using thermogravimetric analysis and differential scanning calorimetric (TGA-DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) techniques. In addition, the dissolution performances of some Na2-xAl2-xSixO4 are verified by water leaching. The results demonstrate that the aluminum-bearing minerals in diasporic bauxite are diaspore and kaolinite, which are converted into Na2-xAl2-xSixO4 after calcination with Na2CO3 at 700–1100 °C. Increasing the calcination temperature in the range of 700–1000 °C and the proportion of Na2CO3 results in Na2-xAl2-xSixO4 having lower x value and decomposing into NaAlO2 and Na2SiO3 if Na2CO3 is present in excess. As the mass ratio of bauxite to Na2CO3 is 1, Na1.95Al1.95Si0.05O4 is primarily formed at 900–1000 °C, which has excellent dissolution performance, close to that of NaAlO2. Upon further increasing the calcination temperature to 1100 °C, Na1.95Al1.95Si0.05O4 transforms into Na2-xAl2-xSixO4 with a higher x value, which has worse dissolution performance.
      原文链接:
    • NSTL
    • Elsevier

    Decomposition of organic additives in the oxidative chalcopyrite leaching with hydrogen peroxide

    Lapidus G.T.Ruiz-Sanchez A.
    9页
    查看更多>>摘要：? 2022 Elsevier LtdRecent investigations have shown that the addition of short-chain organic additives (methanol, ethanol, ethylene glycol, acetone, isopropanol, formic and acetic acids), surfactants (Tween 20 and 80) and organic ligands (EDTA, oxalic and citric acids) in acidic leaching solutions with hydrogen peroxide, significantly promote chalcopyrite dissolution. However, despite these positive findings, until now, the relation between the percentage of dissolution of chalcopyrite, hydrogen peroxide decomposition by Fenton and Fenton type reactions, and the level of decomposition (partial or complete oxidation to CO2 and H2O) of organic additives due to electrophilic attack by the OH* radical, has not been reported. For that reason, a systematic study was undertaken to explore those aspects. The results demonstrated that all the organic additives slowed, but did not prevent the decomposition of hydrogen peroxide, which favored the production of OH*, a radical with elevated oxidizing power capable of promoting the oxidation of organic additives. The degree of organic compound (RH) mineralization (complete oxidation to CO2 and H2O) was structure-dependent, as well as the R* reactivity with H2O2, dissolved copper and iron, although it was not proportional to H2O2 decomposition. Finally, it was found that cyclohexanol is the most promising organic additive because it greatly slows the decomposition of hydrogen peroxide, but it is not mineralized by the OH* radical, and substantially improves chalcopyrite dissolution.
      原文链接:
    • NSTL
    • Elsevier

    Comparison of flip-flow screen and circular vibrating screen vibratory sieving processes for sticky fine particles

    Yu C.Pu K.Geng R.Qiao D....
    15页
    查看更多>>摘要：? 2022 Elsevier LtdScreening is a separation process that classifies materials according to their particle size and is a key unit for mineral processing and utilization. Recently, vibrating flip-flow screens (VFFSs) characterized by large vibration intensity of the screen surface and high efficiency for sticky fine particles have been widely applied. Unlike the traditional vibrating screens, the VFFS is a two-body vibration system, including two vibrating bodies, comprising the main screen frame and a floating screen frame. In this paper, a single-deck type of 0827 VFFS excited by an exciter was designed and produced, and a five-degree-of-freedom translational and rotational dynamic model and equations reflecting the VFFS's motion behavior were established. Then, the dynamic characteristics and spatial trajectories of the main and floating screen frame were investigated through the theoretical analysis and vibration testing. When the connecting stiffness between these two screen frames is very large, the two-body VFFS becomes a single-body circular vibrating screen (CVS). Through screening experiments on the CVS and VFFS, the screening behaviors of sticky fine materials were further studied. The results show a phenomenon of fine particles adhering to the screen surface in the process of screening the sticky fine materials with the CVS. In addition, due to the effects of adhesion and agglomeration, 3–1 mm and 1–0 mm particles cannot easily pass through the screen aperture. The screening efficiency is only 61.99 %, and the total misplaced materials is 9.82 % in the CVS. Compared with the CVS, due to the larger vibration intensity of the sieve mat in the VFFS, there are almost no adhered fine particles on the screen surface. Furthermore, the larger vibration acceleration of the screen surface can improve the desorption and depolymerization of fine particles. Therefore, the screening performance of the VFFS is significantly better than the CVS, with a screening efficiency of 77.62 % and total misplaced materials of 5.76 %.
      原文链接:
    • NSTL
    • Elsevier

    Comparison of sphalerite concentrate leaching by chemical and microbially produced ferric sulfate

    Muravyov M.Panyushkina A.
    10页
    查看更多>>摘要：? 2022 Elsevier LtdHigh-temperature ferric leaching is a promising method to improve the recovery of nonferrous metals from sulfide ores and concentrates. In this study, differences in the leaching kinetics of a sphalerite concentrate using chemical and biogenic ferric iron have been revealed. A comparison of leaching with a (i) biosolution containing ferric iron produced by microbial cells assigned to the strain Leptospirillum ferriphilum BUT, (ii) cell-free iron-containing L. ferriphilum culture liquid, and (iii) commercial reagent of ferric iron indicated that the latter allowed the maximum zinc and copper extraction into the solution. It is suggested that the products of the microbial cell lysis interacted with metal cations, decreasing their reactivity, and slowed down the removal of products from the reaction zone. This led to the formation of a dense layer of reaction products coating sulfide minerals. Probably, the rate of zinc and copper leaching was controlled by both the diffusion of the oxidant through a layer of the reaction products and a chemical reaction on the surface of mineral particles, indicating a mixed type of control. This pattern was independent of the chemical or biological origin of the ferric iron solution. The results provide new insights into the kinetic patterns and structural changes of sulfide minerals during ferric leaching and may contribute to the intensification of the processing of sulfide raw materials.
      原文链接:
    • NSTL
    • Elsevier