Beneficiation of the gold bearing ore by gravity and flotation

Gold concentration usually consists of gravity separation, flotation, cyanidation, or the combination of these processes. The choice among these processes depends on the mineralogical characterization and gold content of the ore. Recently, the recovery of gold using gravity methods has gained attention because of low cost and environmentally friendly operations. In this study, gold pre-concentrates were produced by the stepwise gravity separation and flotation techniques. The Knelson concentrator and conventional flotation were employed for the recovery of gold. Gold bearing ore samples were taken from Gümüshane Region, northern east part of Turkey. As a result of stepwise Knelson concentration experiments, a gold concentrate assaying around 620 g/t is produced with 41.4wt% recovery. On the other hand, a gold concentrate about 82 g/t is obtained with 89.9wt% recovery from a gold ore assaying 6 g/t Au by direct flotation.

Recovery of iron from copper slag by deep reduction and magnetic beneficiation

Aiming at recovering iron from high-iron-content copper slag, this article introduced a combination technol- ogy of deep reduction and magnetic beneficiation, investigated the iron recovery efficiency and optimized the technical conditions. When coke powder with 86wt% fixed carbon was used as a reductant, iron was successfully extracted from the copper slag. Under the optimized condition of the coke powder content of 14wt%, the calcium-to-silicon mass ratio （Ca/Si） of 0.2, the roasting temperature of 1300℃, the roasting time of 3 h, the grinding time of 20 min, and the magnetic field intensity of 61 kA-m-1, the iron recovery rate of the copper slag can reach 91.82%, and the extracted iron powder has an iron grade of 96.21%. With the characteristics of high iron grade and low impurity content, the extracted iron powder can be used as high-quality raw materials of weathering steel.

Progress in developments of dry coal beneficiation

China’s energy supply heavily relies on coal and China’s coal resource and water resource has a reverse distribution.The problem of water shortages restricts the applications of wet coal beneficiation technologies in drought regions.The present situation highlights the significance and urgency of developing dry beneficiation technologies of coal.Besides,other countries that produce large amounts of coal also encounter serious problem of lack of water for coal beneficiation,such as American,Australia,Canada,South Africa,Turkey and India.Thus,dry coal beneficiation becomes the research hot-points in the field of coal cleaning worldwide in recent years.This paper systematically reviewed the promising research efforts on dry coal beneficiation reported in literature in last 5 years and discussed the progress in developments of dry coal beneficiation worldwide.Finally,we also elaborated the prospects and the challenges of the development of dry coal beneficiation.

FINE COAL AND THREE PRODUCT DRY BENEFICIATION WITH VIBRATION AND DOUBLE-DENSITY FLUIDIZED BEDS

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Research on new beneficiation process of low-grade magnesite using vertical roller mill

We investigated whether the vertical roller mill can be efficiently used in the beneficiation of low-grade magnesite and whether it can improve upon the separation indices achieved by the ball mill.We conducted experiments involving the reverse flotation and positive flotation of low-grade magnesite to determine the optimum process parameters,and then performed closed-circuit beneficiation experiments using the vertical roller mill and ball mill.The results show that the optimum process parameters for the vertical roller mill are as follows:a grinding fineness of 81.6wt%of particles less than 0.074 mm,a dodecyl amine(DDA)dosage in magnesite reverse flotation of 100 g·t?1,and dosages of Na2CO3,(NaPO3)6,and NaOL in the positive flotation section of 1000,100,and 1000 g·t?1,respectively.Compared with the ball mill,the use of the vertical roller mill in the beneficiation of low-grade magnesite resulted in a 1.28%increase in the concentrate grade of MgO and a 5.88%increase in the recovery of MgO.The results of our causation mechanism analysis show that a higher specific surface area and greater surface roughness are the main reasons for the better flotation performance of particles ground by the vertical roller mill in the beneficiation of lowgrade magnesite.

Primary beneficiation of tantalite using magnetic separation and acid leaching

Primary beneficiation was successfully performed prior to dissolution of manganotantalite （sample A） and ferrotantalite （sample C） samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and -2wt% each of Nb205 and Ta205 were removed from sample C （ferrotantalite） using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe203 and TiO2, respectively, and -2wt% each of NbEOs and Ta2O5 were removed from sample A （manganotantalite）. A temperature of 50℃ and a leaching time of 3 h in the presence of concentrated HESOa were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.

Beneficiation of coal using supercritical water and carbon dioxide extraction:sulfur removal

This work explores the use of carbon dioxide,water,and their mixtures as solvent for the precombustion beneficiation of raw coal without using any toxic mineral acids in the temperature range of 200-400℃.The fluid polarity,ionic constant,and supercritical point can be adjusted by H_(2)O/CO_(2)ratio and temperature.Adding carbon dioxide to hydrothermal fluid also increases the ionization by forming carbonic acid.Extractions with supercritical fluids have several benefits including enhanced mass transport,ease of separation and recycle,wide range of extractive capability and tunability,better inherent safety,and in the case of carbon dioxide and water-low cost.A semi-continuous extraction system was designed and built in which pressure,temperature and the relative flow rates of CO_(2)and H_(2)O can be controlled.Coal powder is kept in a packed bed and the extraction is carried out at 143 bar pressure.Using sulfur as a model heteroatom,extractive efficiency is examined as a function of the temperature,fluid composition,fluid flow,and extraction time.The results indicate that carbon dioxide,water,and supercritical water-carbon dioxide(ScWC)all can effectively extract about 50%of total sulfur from bituminous coal in 1 h.Extraction above 350℃decreased effectiveness,and extraction above the supercritical point of pure water caused hydrothermal carbonization.ScWC extraction may provide necessary control to prevent organic dissolution while removing sulfur.

Negative-pressure pneumatic separator:a new solution for hard-coal beneficiation

Hard coal is an important source of energy worldwide.Owing to the imperfections of excavation technology,most run-of-mine coals must be processed before they can be utilised as fuel.In this study,tests on the dry separation process were performed with numerous different raw hard coal and coal waste material samples,using a newly designed and constructed negative-pressure pneumatic separator(NPPS).The experiments revealed the effects of the feed-material properties and material processing conditions.These experiments were preceded by additional tests for evaluating the influence of each device operating parameter on the process,to determine the optimal method of supplying the feed material.The calorific value of the processed materials was improved by 5%–40%,while a minimal output yield of products(60%–70%)was maintained.The trials indicated that in coal material processing,the developed NPPS can be used for not only raw coal enrichment but also coal recovery from materials stored at coal-waste dumps.The main advantages of the device are its mobility,low material processing cost,and lack of water consumption during operation.

Quantitative mineralogical characterization of chrome ore beneficiation plant tailing and its beneficiated products

Mineralogical characterization and liberation of valuable minerals are primary concerns in rnineml processing industries. The pre- sent investigation focuses on quantitative mineralogy, elemental deportment, and locking-liberation characteristics of the beneficiation of tailings from a chrome ore beneficiation plant in the Sukinda region, Odisha; methods used for the study of the beneficiated tailings are QEMSCAN~, X-ray diffraction （XRD）, and mineral chemistry by a scanning electron microscope equipped with an energy-dispersive spec- trometer （SEM-EDS）. The tailing sample was fine grained （69.48wt% below 45 μm size）, containing 20.25wt% Cr203 and 39.19wt% Fe203, with a Cr：Fe mass ratio of 0.51. Mineralogical investigations using QEMSCAN studies revealed that chromite, goethite, and gibbsite are the dominant mineral phases with minor amounts of hematite, kaolinite, and quartz. The sample contained 34.22wt% chromite, and chromite liberation is more than 80% for grains smaller than 250 ~tm in size. Based on these results, it was predicted that liberated chromite and high-grade middling chromite particles could be separated from the gangue by various concentration techniques. The tailing sample was beneficiated by hydrocyclone, tabling, wet high-intensity magnetic separation （WHIMS）, and flotation in order to recover the chromite. A chromite concentrate with 45.29wt% Cr203 and a Cr：Fe mass ratio of 1.85 can be produced from these low-grade chromite ore beneficiation plant rejects.

Integrated Mineralogical Characterisation of Banded Iron Ores of Orissa and Its Implications on Beneficiation

Iron is a primary raw material for steel industry. Increase in demand for steel puts pressure on iron resources of India in respect of its grade and reserve. With increase in demand for good grade of ore vis-a-vis its limited reserve, the utilization of low to medium grade iron ores is the order of the day with adoption of advanced beneficiation techniques. In order to find out the effective way of utilization, an in depth mineralogical study is essential as it throws light on the mineralogical peculiarities associated with the ores which affect the resultant beneficiation technique as well as the final product. In order to have a detail insight into the different mineralogical attributes, various characterisation studies megascopic, microscopic (both optical & electron), XRD, mossbauer and VSM are undertaken on the iron ores from different iron ore formations of Orissa. Importance of integrated mineralogical characterisation in beneficiation of iron ores is discussed.

Alternative beneficiation of tantalite and removal of radioactive oxides from Ethiopian Kenticha pegmatite–spodumene ores

The beneficiation methods for Ethiopian Kenticha pegmatite–spodumene ores were assessed through mineralogical and quantitative analyses with X-ray diffraction（XRD） and energy-dispersive X-ray fluorescence（EDXRF）. The tantalite in the upper zone of the Kenticha pegmatite–spodumene deposit is 58.7wt% higher than that in the inner zone. XRD analysis revealed that the upper zone is dominated by manganocolumbite, whereas the inner zone is predominantly tantalite-Mn. Repeated cleaning and beneficiation of the upper-zone ore resulted in concentrate compositions of 57.34wt% of Ta_2O_5 and 5.41wt% of Nb_2O_5. Washing the tantalite concentrates using 1vol% KOH and 1 M H_2SO_4 led to the removal of thorium and uranium radioactive oxides from the concentrate. The findings of this study suggest that the beneficiation and alkaline washing of Kenticha pegmatite–spodumene ores produce a high-grade export-quality tantalite concentrate with negligible radioactive oxides.

Comparative Beneficiation Study of Gyel Columbite Ore Using Double Stage (Magnetic-to-Magnetic and Magnetic-to-Gravity) Separation Techniques

The comparative beneficiation study of Gyel columbite ore using double stage (magnetic-to-magnetic and magnetic-to-gravity), located in the vicinity of Gyel village in Jos South Local Government Area of Plateau State to metallurgical grade was carried out. The ore sample was sourced from 20 different pits each 1.5 × 1.5 × 2 meters deep, 50 meter apart covering a land of 50 hectares. The samples from the 20 pits were crushed, pulverized and homogenized. 200 kg of the homogenized ore sample was used for the experiment and laboratory works. Chemical characterization of the ore sample was carried out using energy dispersive X-ray fluorescence spectrometer (ED-XFR). Single and double stage concentration tests using magnetic and gravity methods were carried out respectively. The results of the chemical analysis of ore sample reveal that, Pit 1 contains 12.26% Nb2O5, 21.6% Fe2O3, 36.1% SiO2;Pit 20 contains 4.78% Nb2O5, 19.34% Fe2O3, 23.96% SiO2 and the homogenized sample contains 6.71% Nb2O5, 23.1% Fe2O3 and 27.0% SiO2 averagely. The liberation study reveals that the niobium of ore can be liberated over a range of sieve size fractions of -355 + 63 μm for the coarse and -63 + 45 μm for the fine particle size fractions. On the basis of this, sieve size fractions of -1400 + 355 μm (as coarse size), -355 + 90 μm (as medium size) and -90 + 45 μm (as fine size) were used for the concentration tests. The concentration test using the double stage processes revealed that the air-floatation followed by rapid magnetic method produced a concentrate with the highest percent assay of 54.48% Nb2O5 with a recovery of 96.53% followed by the rapid-to-rapid magnetic method which produced a concentrate assaying 52.12% Nb2O5 with a recovery of 86.96%. These results meet and surpass the 50% Nb2O5 stipulated as the acceptable metallurgical grade concentrate for niobium metal production in the literature.

MECHANISM AND APPLICATION OF COAL DRY BENEFICIATION WITH AIR-DENSE MEDIUM FLUIDIZED BED

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Applications of two electric arc plasma torches for the beneficiation of natural quartz

Experimental beneficiation processes of quartz concentrate in arc plasma torches of two different types and electric powers were studied. An emission scanning electron microscope and a universal laser analyzer were used to investigate the structures as well as the size distributions of grains and microparticles. Inductively coupled plasma–mass spectrometry was used to determine the chemical compositions of nonstructural solid-phase mineral impurities in quartz concentrate. Results related to the modified grains' structure and size distribution, the compositions of impurities, and the gas–liquid inclusions in the quartz concentrate were investigated. The total impurities concentrations in the processed grains were found to satisfy the IOTA-STD standard(industry standard for grading high quality fused quartz products). The optimal condition(i.e., the optimal specific plasma enthalpy) for the production of high-purity quartz in arc plasma torches was found to depend on the geological-genetic type and the structural and textural features(i.e., chemical composition and gas–liquid inclusions) of the quartz concentrate.

Beneficiation and Characterization of Detrital Zircons from Beach Sand and Red Sediments in India

This paper deals with the recovery of zircon minerals from beach sand and red sediments of bad land topography and flow sheets with material balance are suggested. The experimental data reveal that the total heavy mineral content of red sediment sample is 43.9% in which zircon mineral concentrate is 2.75% by weight, where as for beach-dune sand sample the THM content is 16.7% in which zircon mineral concentrate is 0.16% by weight. It is found that U and Th and REE elements contents are much higher in red sediment zircon sample than beach sand zircon. Zircon concentrates recovered from beach-dune sand and red sediments contain 98 to 98.1% zircon with 79.6 to 80% recovery respectively. These zircon minerals from both the sources are suitable for industrial applications.

Liberation Size and Beneficiation of Enyigba Lead Ore, Ebonyi State, South-East Nigeria

This research work centered on the determination of Liberation Size and Enrichment of Enyigba Lead Ore in Ebonyi state, Nigeria. The study reviews the fundamental operations in mineral processing i.e. the comminution process for the release and liberation of the valuable minerals particles from the ore association, and the eventual separation and concentration of the valuables from the gangue. The ore was pulverized, sieved to liberation size and beneficiated. The mesh of grind was found to be 189 μm, and the liberation size was established to be 63 μm sieve size having the highest percentage of lead of 15.1% then enriched to 69.8% by froth flotation method and was assessed by using x-ray fluorescence (XRF). The lead concentrate by weight was obtained to be 81.80%, confirmed being of high economic grade having surpassed 60% wt Pb element in an ore. It is hoped that this will enhance its development to meet both local and international demand for potential investment opportunities.

Recovery of Iron Bearing Minerals from Beneficiation Plant 2 Thickner Underflow of JSW Steel Limited

To identify and establish beneficiation techniques for slime, a comprehensive research work was carried out on beneficiation plant 2 thickener underflow (Tailing). Iron ore slimes (-45 micron ~80.0%) generated at beneficiation plant 2 assaying 46.7% Fe, 10.82% SiO2, and 4.58% Al2O3 have been subjected to various beneficiation studies like cyclone, wet high intensity magnetic separator and flotation to recover the iron bearing minerals. The effects of different operating parameters have been studied to get a product suitable for pellet making. Detailed beneficiation studies indicate that it is possible to obtain a product containing 61.8% to 66.6% Fe, 1.80% to 3.35% SiO2, and 1.65% to 2.40% Al2O3 with 8.0% to 22.3% weight recovery by adopting de-sliming followed by magnetic separation. Within this product grade range the pellet grade fines (JSW norms-minimum 63.0% Fe) consist of 63.0% Fe, 2.97% SiO2 and 2.48% Al2O3 with 16.9% weight recovery and 56.9% Fe recovery at 0.5 Tesla magnetic field intensity, pulsation rate 230 rpm and 2 min residence time.

Influence of Microstructure on Beneficiation of Low-Grade Siliceous Manganese Ore from Orissa, India

Two low-grade siliceous manganese ores such 1) siliceous crystalline and 2) siliceous cherty types from north Orissa, Indiawas mineralogically characterized and investigated for their possible upgradation. Both the Mn-ore types were subjected to different physical beneficiation techniques under identical conditions and results reported. The results revealed that in the case of low-grade siliceous crystalline type Mn-ore a feed having 26% Mn could be upgraded to more than 45% Mn by dry magnetic separation with 69% recovery at 1.00 tesla magnetic intensity. But the cherty type Mn-ore could not respond well to any of the beneficiation techniques, particularly dry magnetic separation, because of poor liberation even at a size fraction below 100 mesh, though the other type gives best result at this size fraction.

Beneficiation Study on a Nigerian Baryte Ore for Industrial Use

Beneficiation study on samples of baryte ore from Azare in the Plateau State of Nigeria was carried out using chemical analysis, atomic absorption spectrophotometric analysis, jigging and magnetic separation. Results show that Azare baryte can profitably be concentrated for use in oil drilling and other industrial purposes. Barium sulphate content in the head ore analyzed, is 98%. Comparison between jigging and magnetic separation shows that jigging produces a more satisfactory result.

The Upper Cretaceous-Paleogene of Phosphate Clays of the Ouled Bou Sbaa Deposit: Mineralogy, Geochemistry, and Beneficiation (Meskala, Morocco)

This work aims first to characterize the Maastrichtian and Paleogene clays of the Ouled Bou Sbaa phosphate deposit located in the northern part of the Meskala Basin;and as a second goal, the most efficient clay fractions are tested and identified for organic dyes removal. Several techniques and methods have been adopted for the characterization of clays: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), Scanning electron microscope (SEM), and thermogravimetric analysis (TGA). Tests for the removal of methylene blue from clays were carried out by adsorption. The XRD study shows that the clays of the Ouled Bou Sbaa deposit contain fibrous clay types of palygorskite and sepiolite, and phyllite clays such as montmorillonite and illite. Stratigraphically, the Maastrichtian sample yielded, mainly aluminous clays dominated by montmorillonites, while in the Paleogene clays, the palygorskite-types clays, also rich in magnesium, are more common. The results of FTIR, XRF and SEM analyses confirm the mineralogical data, respectively, by the presence of characteristic bands and the dominance of oxides of silica, aluminum, magnesium, and the large dominance of palygorskite which is presented in the form of bundles or platelets of long fibers and montmorillonite which is presented in the form of a stack of sheets. The adsorption of methylene blue (MB) on these clays showed very fast fixation kinetics and a very efficient purifying power for this organic pollutant. The equilibrium isotherms were determined using the Langmuir, Freundlich and Elovich models. The results show that the Freundlich isotherm had better agreement with the methylene blue on clay with a correlation coefficient of 0.959.