处理较大尺寸低磁性铁含量铁矿物的HQW型湿式磁选机

介绍了一种处理较大尺寸铁矿物的湿式筒型磁选机。它处理粒度介于湿式磁选机和干式磁选机处理粒度之间,适用于低品位或低磁性铁含量的铁矿石,以及尾矿再选,具有较高分选效率和处理能力,提高了产量,降低了成本。     

Physical Methods and Flotation Practice in the Beneficiation of a Low Grade Tungsten-Bearing Scheelite Ore

In this paper, beneficiation studies were carried out on a low-grade tungsten-bearing scheelite from Nezam Abad ore with total WO₃ grade of 0.11%. Mineralogical studies showed that scheelite is mainly distributed in the ore and gangue minerals include Quartz and Tourmaline. Liberation degree (d₈₀) of tungsten- bearing scheelite is achieved around particles size 150 μm. Gravity concentration, magnetic and flotation methods were conducted by using experimental designs including fractional factorial and response surface methodology. Gravity concentration results indicated that jig separator could not be able to improve tungsten grade in size fraction +600–1750 μm; however, shaking table increased feed grade up to 27.05% with total recovery more than 50% by using four stages concentration in the size range of +125–600 μm. Multi Gravity Separator (MGS) applied on the intermediate products, improved efficiently the total tungsten recovery of the circuit. The results of flotation practice on the pre-concentrated product demonstrated that WO₃ grade could be increased up to 9.2% with total recovery of 27.04% by using one stage rougher and four stages of cleaning. Different methods including MGS, wet and dry magnetic separation were considered for upgrading fines from grinding stages; however, only MGS result was satisfactory. The MGS produced a product with WO₃ grade 0.64% and total recovery 93%.     

Chemical-Enhanced Washing for Remediation of Soils Contaminated with Marine Diesel Fuel in the Presence/Absence of Pb

The effects of the operating conditions, the initial concentrations of marine diesel fuel (MDF) and the coexisting Pb in the soil, and the ethylene diamine tetra acetic salt (EDTA) in solution on MDF removal by sodium dodecyl sulfate (SDS) washing were extensively investigated with the aim of optimizing the process parameters and determining the MDF removal efficiency by SDS under different contamination conditions. The experimental results from batch tests indicated that the majority of MDF was removed by SDS in the first 2?h, and its optimal pH was nearly neutral. Increasing the SDS concentration linearly increased the MDF removal efficiency. At a given SDS concentration, the removal efficiency was dependent on the existing forms of MDF in soils, and the free phase of MDF was found to be more easily removed than the adsorbed phase. MDF removal by SDS was significantly reduced by the coexisting Pb in soils, which likely forms a complexation with SDS and thereby enhances the partitioning of MDF in the soil by the re-adsorption of released MDF onto the hydrophobic tails of the adsorbed SDS. EDTA alone, or with SDS, could remove MDF, but the remaining MDF in the contaminated soil after EDTA washing became more difficult to be removed by SDS. Therefore, the EDTA washing followed by SDS washing is not recommended for MDF removal.     

连续式磁性颗粒去除器永磁分离机理及其影响分析

文章就连续式磁性颗粒去除器中磁性悬浮颗粒在磁场中受力分析，从而获得磁性悬浮颗粒最小捕获粒径的计算公式，进而指导试验，提出提高捕获率的措施．     

Physical Modeling of Hydrodynamic Separators Operating with Underflow

Model studies using geometrically similar 300-mm-diameter and 1,600-mm-diameter hydrodynamic separators operating with an underflow have confirmed earlier results indicating that a combination of Froude and Hazen scale laws should be used when predicting prototype separator performance. A hybrid equation is proposed to scale the model inflow rates. This equation provides a good fit to the observed prototype flow versus efficiency data. The need to scale particles using a Hazen scale for settling velocity and a Froude scale for flows is discussed. Treatment factors are calculated for the different particle sizes used, and these confirm the suitability of the device to remove particles with higher settling velocities while passing organic particles with low settling velocities forward to treatment when the device is configured as a grit separator.     

Process mineralogy of suspended particles from a simulated commercial flash smelter

Polished sections of pyrometallurgical intermediate products from a simulated commercial flash furnace were examined by reflected light microscopy, scanning electron microscopy-energy dispersive spectrometry and electron backscatter analysis, and microprobe analysis for phase and textural relationships. The smelter feed is a copper concentrate from a porphyry copper deposit. The concentrate consists primarily of chalcopyrite, bornite, and pyrite with smaller amounts of covellite, chalcocite, molybdenite, magnetite, galena, and sphalerite. The flash furnace reactions for pyrite and chalcopyrite can be observed by reflected light microscopy. Reacted angular particles of pyrite exhibit successive rims of fibrous pyrrhotite and hematite or magnetite. Reacted angular chalcopyrite particles show successive rims of bornite, digenite, and chalcocite. Spherical particles, formed by the complete melting of former pyrite and chalcopyrite particles, consist of variable amounts of granular pyrrhotite with magnetite rims and minor hematite. Spherical particles, formed by the complete melting of former chalcopyrite particles, exhibit exsolution intergrowths with varying proportions of intermediate solid solution, bornite, digenite, and chalcocite, and have rims of hematite, magnetite, and copper-iron spinel. Electron microprobe analyses show that the iron oxides contain significant copper and minor zinc in their structures. Sphalerite and molybdenite do not show evident mineralogical reactions.     

Process mineralogy of suspended particles from a simulated commercial flash smelter

Polished sections of pyrometallurgical intermediate products from a simulated commercial flash furnace were examined by reflected light microscopy, scanning electron microscopy-energy dispersive spectrometry and electron backscatter analysis, and microprobe analysis for phase and textural relationships. The smelter feed is a copper concentrate from a porphyry copper deposit. The concentrate consists primarily of chalcopyrite, bornite, and pyrite with smaller amounts of covellite, chalcocite, molybdenite, magnetite, galena, and sphalerite. The flash furnace reactions for pyrite and chalcopyrite can be observed by reflected light microscopy. Reacted angular particles of pyrite exhibit successive rims of fibrous pyrrhotite and hematite or magnetite. Reacted angular chalcopyrite particles show successive rims of bornite, digenite, and chalcocite. Spherical particles, formed by the complete melting of former pyrite and chalcopyrite particles, consist of variable amounts of granular pyrrhotite with magnetite rims and minor hematite. Spherical particles, formed by the complete melting of former chalcopyrite particles, exhibit exsolution intergrowths with varying proportions of intermediate solid solution, bornite, digenite, and chalcocite, and have rims of hematite, magnetite, and copper-iron spinel. Electron microprobe analyses show that the iron oxides contain significant copper and minor zinc in their structures. Sphalerite and molybdenite do not show evident mineralogical reactions.     

旋风子中气相流动特性及颗粒分离效率的数值研究

采用Fluent软件对轴向进口旋风子内的气相流场和颗粒分离效率进行了三维数值研究。用RNG（重整化群）κ－ε湍流模型模拟气相紊流特性。采用拉格朗日模型对固相颗粒的轨迹进行了模拟,并对固体颗粒的分离效率进行了分析。     

Development of a Fluidized Dry Magnetic Separator and Its Separation Performance Tests

ABSTRACT

In order to efficiently purify and recover the magnetite powder (dense medium) in the process of dry coal preparation of air-dense medium fluidized beds, a new type of fluidized dry magnetic separator was developed in this paper by changing the feeding device and mode, the location and structure of the separating tank, and the particles’ movement direction in the separating tank on the basis of the traditional permanent drum dry low-intensity magnetic separator. The magnetic pole arrangement, magnetic field intensity, magnetic field gradient, and action depth of magnetic field of the magnetic system were studied to determine the reasonable parameters of magnetic system for magnetic separation tests. The results of magnetic separation tests for the mixture of magnetite powder and coal powder show that the fluidized dry magnetic separator can improve the grade of magnetite powder as much as possible on the basis of ensuring the recovery of magnetite powder, and obtain the high efficiency purification and recovery of magnetite powder.     

Simultaneous Prediction of Saturated Hydraulic Conductivity and Drainable Porosity Using the Inverse Problem Technique

The saturated hydraulic conductivity K and the effective porosity f are two important input parameters needed for lateral drain spacing design, as well as some other applications. The technical and economic justification, of most drainage projects, is mainly connected to these two parameters. The current design procedure is based upon calculation of the lateral spacing, using some average values of K and f within the drainage area. The objectives of this study were to introduce a new method for simultaneous estimation of K and f parameters using the inverse problem technique, and to evaluate five different unsteady drainage analytical models of the Boussinesq equation, suggested by different researchers for simultaneous prediction of the parameters. Consequently, five different analytical models for predicting water table profiles were solved, using the inverse problem technique. Each model was then evaluated. A physical drainage model of 2.2?m length, 0.3?m width, and 0.5?m height was established in the laboratory and carefully packed with a sandy loam soil. A perforated drainage pipe of 4.5?cm in diameter was installed at the bottom end of the model. Many piezometers were inserted in the soil for spatial and temporal water table monitoring. Different data sets from the experiments and literature were used for model calibration. The newly proposed approach that is based upon measuring water table profiles, at different times, was then evaluated with both constant and variable f. The predicted values of the proposed approach indicated reasonable agreement with the measured data. With variable effective porosity, the method was even more accurate to predict the water table profiles. Using the inverse problem technique, all the analytical models provided good agreement with the measured data. Among these, however, the Topp and Moody model predicted more accurate results than other models.     

Effect of the Morphological Types in Grinding of Iron-Ore Products

The iron-ore products are characterized in order to investigate the effect of the mineralogical features on the grinding results into pelletizing plant. The studied materials are from four mines of the different regions of Iron Quadrangle, processed by flotation, magnetic separator and produced from screening with P₈₀ in 8 mm. In this study, we apply for the first time the novelty of electron backscatter diffraction technique for the iron ore phase identification and quantification of the microstructural parameters. The mineralogical and microstructural parameters were introduced as a base in the specific grinding test applied in the industrial routine. Each sample was characterized based on the mineral shape, pores, fractures, polycrystalline hematite, and aggregate of hematite with goethite. The test results demonstrate that there is a strong relationship between the gain of the specific surface area, represented by the K-factor, and the morphological types.     

SVE Design: Mass Transfer Limitation due to Molecular Diffusion

Vaporization and soil adsorption are the two mass transfer mechanisms that control contaminant recovery rates for soil vapor extraction (SVE) systems. At most soil remediation sites, contaminants are distributed among three phases, namely, soil particles, pore water, and soil vapor. Contaminant mass transfer from adsorption sites into a convective vapor stream involves desorption, diffusion through pore water, and vaporization into soil vapor. An SVE design model is proposed to describe this three-phase mass transfer process and assist the design and evaluation of SVE systems. The model contains analytical solutions developed to estimate contaminant concentrations in the vapor phase and predict contaminant removal rates. Monitoring data from two full-scale SVE systems were used for model development and calibration. The results suggest that contaminant diffusion through the pore water is the rate-limiting step and leads to remediation inefficiency of an SVE system. Mass transfer retardation from molecular diffusion in water is likely the major contributing component to the venting efficiency coefficient of Staudinger et al.     

一种具有高速旋转磁系的干湿磁选机初级模型

经过大量查阅磁选机和磁系的发展现状资料和总结整理后发现,铁矿石磁选过程中的磁团聚现象仍是阻碍精矿品位提高的重要原因。为避免其不良影响,本项目对磁选机磁场特性对磁性颗粒的受力和运动的影响进行了研究,并计划采用高速旋转的交变磁场,设计一种新型磁系及磁系伸缩调节装置,避免磁性颗粒在磁选过程中磁链的形成和磁性夹杂,从而最大限度提高磁铁矿精矿品位。     

Oil Spill Remediation Using Magnetic Separation

Magnetic separation technology was applied to remove dispersants and crude oil from water with magnetite and maghemite. Maghemite exhibited rather constant removal efficiency for dispersants regardless of surfactant types, while magnetite exhibited higher removal efficiency for anionic surfactant, and the efficiency was higher in deionized water than in salty water that contains more ions. Sorption of the dispersants to magnetite can be explained with electrostatic attraction, while binding of the dispersants to maghemite can be described with electrostatic attraction as well as with the structural characteristics that provide high sorption capacity. The result from a water bath experiment, which was to test the collection efficiency of magnetic particles from water, indicated that the recovery efficiency of magnetic particles was nearly 100% after the dispersants had been sorbed. More than 80% of the oil was collected when the magnetite-to-oil ratio was more than 0.89, while the same percentage of oil was harvested when the maghemite-to-oil ratio was more than 0.46 in the oil removal experiment. Sorption of crude oil to magnetic particles can be explained with the fine particle–oil flocculation, which is associated with an electrostatic attraction between the magnetic particles with charged surface and polar compounds in the crude oil.     

Behaviour of manganese oxides during magnetising reduction of Baharia iron ore by CO–CO2 gas mixture

Abstract

High manganese containing iron ore samples were isothermally reduced with a CO–CO₂ gas mixture at 600–1000°C. The course of reduction was followed by a weight loss technique. The influence of reducing gas composition and temperature on the reduction kinetics was investigated. The different phases formed during reduction were identified by X-ray phase analysis, while their structures were microscopically examined. The reduced samples were magnetically tested by means of a Davis tube tester. The effect of grain size, drum speed, and cleaning conditions on the efficiency of magnetic separation was studied using a Box-Mag wet low intensity magnetic separator. The separation efficiency was determined by analysing total iron, manganese, and acid insoluble contents in both magnetic and non-magnetic fractions. Best testing results were obtained on separation of the sample reduced with 80CO–20CO₂ (vol.-%) at 800°C. The optimum grain size for magnetic separation is below 0·15 mm while that of the drum speed is 100 rev min^-1 . The cleaning of the magnetic fraction increases the iron content and decreases the manganese and acid insoluble contents.     

Optimization of Settling Tank Design to Remove Particles and Metals

Mass reduction rates of particles and metals were simulated for a two-compartment settling tank composed of a storage compartment and a continuous flow compartment. Particle-size distribution, rainfall, and flow data from 16 storm events measured at three highway sites were used. The volume ratio (i.e., ratio of surface areas for a given depth) between storage and continuous flow compartment was optimized for a given design storm size to maximize total mass reduction rates of particles and heavy metals. Measured settling velocity profiles of runoff samples were used in the simulation. Simulation results showed that in a given total design storm, larger storage compartment fractions (>0.95) enhanced the removal of smaller particles (2–104?μm) and particulate phase metals, and even a small fraction (<0.05) of continuous flow compartment effectively removed larger particles (104–1,000?μm). A volume fraction of 0.75 for the storage compartment is suggested to optimize annual reductions of particles and associated heavy metals.     

Innovation Features of a New Magnetic Separator and Classifier

Abstract

A short review of magnetic separation methods sharing some sort of similarities with the new magnetic separator and classifier developed is presented. A short review of the magnetic separation methods inherently exhibiting some sort of magnetic classification process is presented. The main innovation features of the new magnetic separator and classifier developed are described, mainly the ability to provide a differential magnetic classification of the magnetic particles, which is shown to be a novel process by itself.     

Experimental Studies on Heavy Metal Extraction from Contaminated Soil Using Ammonium Citrate as Alkaline Chelate during the Electrokinetic Process

Researchers have performed experimental studies using ammonium citrate (AC) during the electrokinetic (EK) remediation process for the extraction of cadmium (Cd) and copper (Cu) from the contaminated soil. They evaluated the efficiency of ammonium citrate by considering it as a washing solution and a purging solution at the anode electrode compartment. The efficiency of electrokinetic extraction was observed to be significantly influenced by the pH and buffering nature of the soil medium. The experimental studies indicate that the removal of cadmium and copper was 48.9% and 30.0%, respectively, when ammonium citrate was used both washing and purging solution. The solubility of both cadmium (Cd++) and copper (Cu++) in EK-treated soils has also been estimated by sequential extraction studies with deionized (DI) water. The analytical techniques, X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscope (SEM) provide the evidence of migration of cations during treatment of contaminated soil by process of electroosmosis (EO). The SEM images of both cadmium- and copper-contaminated soils show that these soils have a fluffier and more porous structure. This might be caused by the change in surface charges of the clay particles as a result of introduction of heavy metals. The mineralogical compositions of soil are not altered significantly by electrokinetic process.     

Mineralogy,physical characterization and magnetic separation performance of a raw ilmenite concentrate for its purification

Mineralogy, physical characterization and magnetic separation performance were investigated for purification of a raw ilmenite concentrate. With the aid of mineral liberation analyzer (MLA) and optical microscope, it was found that (1) most of heavy minerals were distributed in the narrow size fraction, (2) clays and Ti-bearing magnetite needed to be separated prior to magnetic separation, (3) harmful elements such as Ca, P, ²³²Th and except Mg would’t be enriched in ilmenite concentrate, but enrichment of Mg could’t affect the concentrate quality, (4) Monazite was the main carrier mineral of Th, Ca and P. In addition, the expected yield of rejection and theoretical magnetic inductions were determined by separation tests of heavy minerals and magnetic analysis, respectively. Both the wet and dry magnetic separations were performed focusing on the examination of magnetic induction and it was found that the dry separator has an excellent selectivity against radionuclide bearing minerals. Finally, the dry magnetic separation as a core process technology was proposed to purify the raw concentrate.     

Cr-Polluted Soil Studied by High Gradient Magnetic Separation and Electron Probe

An Fe-rich soil from the site of a former leather tannery, heavily polluted with Cr, was studied using a combination of wet chemical analysis, high gradient magnetic separation (HGMS), and electron probe microanalysis (EPMA). It is demonstrated that such a combination is a powerful tool for the characterization of polluted soils, especially in cases where the pollution is present as discrete particles. Both EPMA and magnetic separation data indicated that the Cr pollution was present as a hydrous Cr-oxide phase. The Cr does not correlate with the Fe minerals, most likely as a result of the initial high Cr concentrations in the soil, which lead to precipitation of separate hydrous Cr-oxide minerals and Fe minerals. The Cr-containing material is present as (layered) aggregates, which are formed around larger quartz grains or around very small other particles that served as precipitation nuclei. Magnetic separation tests show that the Cr pollution can largely be removed by HGMS.