Siliceous Ore Research Articles

Ammoniacal Solvoleaching of Copper from High-Grade Chrysocolla

The copper silicate ore chrysocolla forms a large potential copper resource, which has not yet been fully exploited, due to difficulties associated with its beneficiation by flotation and metallurgical processing. Direct acid leaching of chrysocolla causes silica gel formation. Therefore, in this work, the feasibility of solvometallurgical methods to leach copper from high-grade chrysocolla while avoiding issues with silica gel formation was assessed. Ammoniacal solvoleaching was performed with a solvent comprising the chelating extractant LIX 984 N or the acidic extractant Versatic acid 10 in an aliphatic diluent (ShellSol D70 or GTL Fluid G70), combined with a small volume of aqueous ammonia. In the three-phase system, aqueous ammonia dissolves copper from milled and sieved chrysocolla, while copper is simultaneously extracted to the organic phase, releasing ammonia that can be reused for further extraction. The best results were obtained with LIX 984 N as extractant: using a 50 vol% LIX 984 N solution, about 75% of copper could be extracted after 60 min of leaching at 25 °C. The stripping of copper from the pregnant leach solution was optimized. Quantitative stripping of copper was achieved with 1.89 M sulfuric acid and the final aqueous solution of copper sulfate had a concentration of 33 g L−1. Experiments in a leaching reactor (1 L) and small battery of mixer-settlers (3 stages, 35 and 143 mL effective volume in the mixer and the settler, respectively, per stage) were successfully conducted and allowed to recover copper with a purity of 99.9%. A conceptual flow sheet has been developed.Graphical

A Process Mineralogical Evaluation of Chromite at the Nkomati Nickel Mine, Uitkomst Complex, South Africa

A process mineralogical study based on three texturally and mineralogically different chromite-bearing ore types at the Nkomati nickel mine was undertaken, with focus on chromite. Chromite is a by-product of the Ni-Cu-Co-PGE ore at Nkomati Nickel mine. These being the PCMZ_MG (medium-grade Ni-Cu sulphide silicate ore with disseminated chromite), PCMZ_HG (high-grade Ni-Cu sulphide silicate ore containing disseminated chromite) and MCHR (massive chromite unit) ore types. These were processed using benchtop flotation followed by gravity concentration using a shaking table at different grind sizes. Quantitative mineralogical data was obtained using a 600F Mineral Liberation Analyser for the unprocessed and processed ores at three selected target grinds. The Mineral Liberation Analyser data indicated that increased milling does not relate to increased chromite grades and recoveries, particularly for the disseminated PCMZ type ores based on laboratory-scale gravity concentration. The recovery is controlled largely by the chromite chemistry. The results also showed that the MCHR samples that underwent a pre-flotation stage before gravity separation had better Cr2O3 grades (45% to 47%) and recoveries (52% to 61%) than MCHR ore that did not undergo a pre-flotation stage, which recorded grades ranging from 44% to 46% and recoveries ranging from 43% to 60%. This holds promise for the blending of MCHR ores with the PCMZ ores. The PCMZ ores also displayed better Cr2O3 grades and recoveries at coarser grinds. The optimal target grind to process all three ore types is a P80 of 75 μm, which is the current grind size employed at Nkomati Nickel mine. Due to the low nickel price and grade the Nkomati Nickel mine is currently under care and maintenance.

Processing of Low-Grade Chromite Ore for Ferroalloy Production: A Case Study from Ghutrigaon, Odisha, India

The low-grade siliceous chromite ore from Ghutrigaon, Odisha, India, containing ~ 16% Cr2O3, with Cr/Fe ratio of 1.97 and ~ 55% of SiO2, does not find any use in metallurgical industry and hence considered as waste. Mineralogical investigation indicates the presence of chromite and quartz as major minerals with minor fuchsite and kaolinite. The beneficiation studies reveal that the product can be enriched to a Cr/Fe ratio of 3.35 and 3.02 by gravity concentration (wet shaking table) and wet high intensity magnetic separation, respectively. Tiny Cr-grains within quartz and fine silica dusts within chromite inhibit liberation of chromite resulting in poor response to physical beneficiation. As an alternative, processing of ore through pyro-metallurgical route was evaluated. Chromite fines mixed with carbon and lime in the form of pellets/granules was charged to a plasma reactor. In about ten minutes, the metal globules/prills were separated from the slag in 1:6 ratio. The metal, examined through XRD and optical microscope, was found to be ferrochrome alloy. In situ EDAX analysis indicated the metal to have 61.51% Cr, 26.52% Fe and 13.1% C with minor silica (2.42%), and the slag was composed of Ca2Al2SiO7 which revealed that both metal and slag so obtained could suitably be used in different industries.

New Insights into the Pre-Concentration of Alunite from a Siliceous ore using Froth Flotation

Alunite is the main non-bauxite source of aluminum. Due to the low Degrees Of Freedom (DOF) of alunite, froth flotation, as a pre-concentration method, is a viable alternative to increase selectivity in downstream processes. The current study was aimed at investigating the pre-concentration of alunite using micro-flotation. In the first step, an optical microscope studies were done to determine DOF of alunite. In the next step, flotation tests were designed. The experiments were performed based on the surface charge differential between alunite and quartz using direct and reverse flotation. In the reverse flotation, Ca+2 and Ba+2 were used to activate the quartz surface. Anionic collector was used to float the gangue minerals. The highest grade and recovery using reverse flotation were 34.96 and 81.33%, respectively. In the direct flotation, the surface of alunite was activated using Ba2+, Ca2+ and F-. The optimum condition was achieved using F- as an alunite activator for particles ranged -37+25 µm with the grade of 31.47%. The grade and recovery were 50 and 89%, respectively. All experiments were conducted in Hallimond Tube. During the experiments, several parameters were controlled.

Genetic implications of regional vs. fracture-controlled fluid flow in carlin-type gold deposits, Nevada

The ability to identify differences in the chemistry of hydrothermal solutions that formed Carlin-type gold deposits in areas that experienced regional fluid flow in proximity to Eocene igneous rocks (e.g., the Carlin trend) vs. fracture-controlled fluid flow distal to Eocene igneous rocks (e.g., the Getchell trend) was evaluated using fluid inclusion microthermometry, quadrupole mass spectrometer (QMS) gas analyses, and H-isotopes.Primary fluid inclusions were measured in eleven samples of Main-stage quartz; Late-stage quartz, realgar, and barite; and post-ore calcite interlayered with chalcedonic quartz from the Getchell and Twin Creeks mines. Fluid inclusions in Main-stage jasperoid from the NE-trending Turquoise Ridge Fault are cogenetic one-phase CO2 and liquid-rich that homogenize at 178°–237°C, with salinities of 4.3–6.2 wt% NaCl equiv. Inclusions in Late-stage quartz containing disseminated stibnite have Th of 122°–253°C and salinities of 4.2–6.7 wt% NaCl equiv. Barren realgar hosts inclusions with Th of 65°–119°C and salinities of 0–18 wt% NaCl equiv. Finally, inclusions in hydrothermal barite and post-ore calcite have salinities of 5.7–8.1 wt% NaCl equiv. and 0.9–1.1 wt% NaCl equiv., respectively, but Th overlap between 65°–134°C.Gas data include 22 samples of Late-stage realgar-stibnite-orpiment mineralization from the Getchell, Twin Creeks, and Betze mines. Fluid inclusions in samples of auriferous stibnite from the Getchell trend have total-gas contents ≤ 7.7 mol%; plot near the N2 apex (magmatic gas source) in a N2-Ar-He ternary diagram; and trend from the shallow meteoric to magmatic field of a CO2/CH4 vs. N2/Ar diagram. Barren stibnite and realgar contain gas-poor inclusions (0.01–2.2 mol% total gas), with fluid mixing for realgar indicated by the positive correlation of He-CH4 and data trending from the shallow meteoric to evolved crustal field in a CO2/CH4 vs. N2/Ar diagram.Hydrogen isotopes were measured for nine samples of Main- and Late-stage minerals from the Getchell, Twin Creeks, and Betze mines. Main-stage siliceous ore from the Getchell trend have бD of −128‰ to −98‰, realgar samples from all three mines have бD of −152‰ to −142‰, and two orpiment samples from the Getchell mine have бD of −57‰ and −44‰.Distinct differences are evident in the fluid inclusion and H-isotope data for hydrothermal systems that formed Carlin-type deposits distal vs. proximal to Eocene igneous rocks. Magmatic and crustal fluids dominated in the fracture-controlled Turquoise Ridge deposit, Getchell trend and meteoric water did not become prominent until the formation of post-ore chalcedonic quartz–calcite veins. In contrast, regional flow along the Carlin trend incorporated large amounts of meteoric water. By interpreting H-isotopes with respect to fluid inclusion data for the Carlin and Getchell trends, gold did have a magmatic source in both areas. However, meteoric water also leached gold from country rocks during regional flow to contribute to the large endowment of gold in the Carlin trend. Genetic models used in the exploration for Carlin-type deposits must therefore account for mineralization that is fracture-controlled or related to regional fluid flow.

The Role of Hydrothermal Activity in the Formation of Karst-Hosted Manganese Deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits.

Determination of maximum zinc recovery of Vazante mine ore by flotation process

Abstract Nowadays, Nexa Resources (ex-Votorantim Metais) operates two zinc mines in Brazil, represented by the Vazante unit in Vazante - MG and the Morro Agudo unit in Paracatu - MG. The present study was carried out at the Vazante unit, where zinc concentrate is produced from a silicate ore called Willemite (Zn2SiO4) through froth flotation processes. The two main objectives of the study were the determination of the maximum zinc recovery that could be obtained in flotation bench tests with specific controlled conditions and the mineral characterization of the tailings generated, using a SEM/EDS (scanning electron microscope with energy dispersive x-ray spectroscopy) with MLA (mineral liberation analyzer). The flotation results showed a maximum recovery of 91.91 % with 1.68 % of zinc in the tailings after an eleven-minute flotation. Considering the mean results of all the tests, the maximum zinc recovery obtained was 91.07 % with 1.75 % zinc grade in the tailings. Mineral characterization analysis showed that zinc minerals besides Willemite, such as Gahnite and Franklinite are present in the zinc tailings. In addition, the analysis demonstrated that the Willemite present in the tailings is very fine (80 % < 0.015 mm) and well liberated. With no liberation problems, it was concluded that the main reason responsible for preventing zinc recovery to increase even more along the flotation tests was the presence of the extremely fine Willemite minerals. The test results showed that, to increase zinc recovery, two main processes needed to be considered. The grinding process, that will need to be improved and carefully revised to reduce Willemite fine grain size generation; and the flotation process, regarding bubble formation, reagent addition, resident time and a redesign of flotation machines, aiming to increase the recovery of extremely fine Willemite ore particles.

Ni-smectitic ore behaviour during the Caron process

Niquelândia is a nickel-lateritic ore deposit located in the State of Goiás, Brazil. This deposit is one of the best-known nickel-lateritic orebodies in Brazil and contains both oxidized and silicate ores. In the oxidized ores, nickel is essentially associated with goethite, while in the silicate ores, it is associated with clay minerals, especially smectites. Two types of smectites were found: a nickel-magnesium-rich trioctahedral and an aluminium‑iron-rich dioctahedral structure.Nickel was produced at Niquelândia by the Caron process, a reduction roasting operation followed by ammoniacal leaching; however, due to the collapse of the nickel prices, Niquelândia mine interrupted its activities in 2016. Usually, the Caron process is able to extracts over 90% of Ni from the oxidized ore and less than 60-70% from the silicate ore. At Niquelândia the nickel recoveries varied from 70 to 75% of nickel from the Run of Mine (oxidized+silicate ores).A detailed study of the mineralogy from the silicate ore residues of the Caron process was conducted in order to find out why nickel extraction is not properly performed in this type of ore. The results revealed: 1) higher nickel extraction is assigned to iron-rich dioctahedral smectites and 2) lower nickel extraction is assigned to nickel-rich trioctahedral smectites; finally, 3) the low Fe content of Ni-rich trioctahedral smectites does not allow forming Ni-Fe phases which can be dissolved by the ammoniacal leaching.

Direct Leaching of Low-Grade Zinc Oxide Ore Containing High Amounts of Iron and Manganese

Consumption of zinc metal has been rapidly increased in the world. Zinc metal exists as oxide, sulfide, carbonate and silicate ores, among which zinc oxide ores have not been mined because it is very difficult to separate zinc from gangue or to concentrate using the conventional flotation processes. In the current study, a low-grade zinc oxide ore containing 5.9% Zn, 33.4% Fe and 13.7% Mn was selected to investigate direct leaching. Results of the direct leaching at conventional conditions showed that the Zn leaching efficiency was improved at high acidity, high temperature and grinding conditions and reached about 60% at temperature of 50 °C, d80 of 110 microns, leaching time of 120 min and sulfuric acid consumption of 3.3 kg/kg Zn. Results showed that between 20 and 30% of zinc is associated with other species containing manganese IV. In the reductive leaching experiments by using Na2SO3 as reductant, the maximum Zn and Mn leaching efficiencies are about 82.7% and 96.2%. Dissolving high manganese as impurity in the pregnant solution is a potential concern with the reductive leaching process that needs further investigation.

Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)

The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion.

An Archaeometallurgical Explanation for the Disappearance of Egyptian and Near Eastern Cobalt-Blue Glass at the end of the Late Bronze Age

A recent compositional study of Egyptian cobalt-blue glass from museum collections in Japan (18th Dynasty) and from the site of Dahshur (18th and 19th-20th Dynasties) concluded that a new source of cobalt was exploited for the later Dahshur glass, thereby suggesting that glass production continued into the Ramesside period (Abe et al. 2012). It is shown in the current article that some of this 18th Dynasty glass and the majority of the 19th-20th Dynasty glass had been recycled, not only supporting the general consensus that glass production virtually disappeared by 1250 BC, but that the cobalt source did not necessarily change. It is further proposed, however, that the generally accepted cobalt source for Egyptian glass was not the alum deposits of Egypt's Western Desert, but derived from cobaltiferous siliceous ores, possibly from central Iran. Re-analysis of the compositions of cobalt-blue glass frit found at Amarna, as well as Egyptian and Mesopotamian glass, suggests that the cobalt colourant was a by-product of silver extraction from these ores and can therefore be considered as a concentrated cobalt glass slag, which travelled in the form of a frit to glass producers who added it to locally derived base glasses and/or their precursors. Experiments conducted on ore containing cobalt-nickel arsenides with native silver demonstrate that not only can silver be extracted and that concentrated cobalt glass can be produced simply by adding a flux, but that some components of the ore partition preferentially into the silver or the glass slag, thereby weakening their associations with the other components in archaeological glass. Treating the cobalt-blue colourant as a slag composed of the gangue of a smelting system provides an explanation for the unique elevated levels of alumina and lower levels of potash found in cobalt-blue glasses, as well as providing an explanation for the cessation of cobalt exploitation at the end of the Late Bronze Age. It is suggested that the exhaustion of native silver and siliceous silver ore deposits during the Bronze Age, with argentiferous lead ores becoming the main source of silver, depleted the amount of cobalt available, thereby reducing the amount of glass produced which, in turn, led to increases in recycling during the New Kingdom period.

Siliceous Manganese Ore from Eastern India:A Potential Resource for Ferrosilicon-Manganese Production

Abstract Siliceous manganese ore, associated with the banded iron formation occurs in large volume in northern Odisha, India. It is a sub-grade ore containing 21% Mn, 60% SiO2 and 3% Fe, hence do not find any use and considered as waste. Such ore does not respond to any physical beneficiation techniques because of intricate microstructure and poor liberation of Mn-phase. It could only be up-graded to 32% Mn with 36% yield and 52% recovery by processing it through mineral separator followed by WHIMS. Siliceous manganese ore along with calcite and coke in appropriate ratio, when charged to a plasma reactor, a product with slag metal ratio of 2.5:1 was obtained within a period of 10 min. Electron probe micro-analysis of the metal confirmed it to be ferrosilicomanganese while the slag constitute of tricalcium silicate (C3S) with around 5% Mn in adsorbed state.

Addition of pebbles to a ball-mill to improve grinding efficiency – Part 2

Nkwanyana and Loveday (2017) used batch grinding experiments in a 0.6 m diameter mill to test partial replacement of steel balls (37.5 mm) for secondary grinding, by partly rounded pebbles (19–75 mm) from a SAG mill. At the optimum pebble content of 25% by volume, a 25% saving in steel ball consumption and a 15% saving in energy consumption was achieved, with no change in productivity. These very encouraging results were discussed with operators and designers of SABC circuits.This paper compares the performance of a 25/75 pebble/ball (volume ratio) composite charge to ball-milling, under conditions typical for a ball-mill in SABC circuits, i.e. a large ball top size (75 mm), a high mill speed (75% of critical speed) and a coarse feed top size (19 mm). The volume of pulp in some experiments was increased to mimic pulp filling in an overflow discharge ball-mill. All the experiments in this phase were conducted using a silicate ore. The rate of production of material finer than 75 µm, when using a 25/75 mixture, was virtually identical to that of the corresponding ball-milling experiment. The average saving in energy consumption was about 13% and a saving in ball consumption of 25% applies.It was noted that the replacement of balls by pebbles reduced the rate of grinding of coarse particles. This problem was solved by retaining the original quota of large balls, and replacing only smaller ball sizes. This method had a minimal effect on the rate production of fines (−75 µm) and makes composite secondary milling even more attractive, for reducing the cost of balls.Concerns about accumulation of ‘scats’ (coarse particles) have also been analysed. The effect of scats on ball-mill productivity was tested and it was concluded that scats may not have an adverse effect on productivity in secondary ball-mills and composite mills, if large balls are present. The use of a trommel on the ball-mill is suggested to solve related problems in the classification circuit.

Processing technology of silicate and carbonate uranium-molybdenum ore

Processing technology of silicate and carbonate uranium-molybdenum ore

Lithium Extracting from Zinnwaldite: Economical Comparison of an Adapted Spodumene and a Direct‐Carbonation Process

AbstractLithium is used in a variety of everyday objects. The most important field of application is as components of battery electrolytes and electrodes. Next to salar brines, commercial lithium production relies on mineral ore sources such as spodumene, petalite, and lepidolite. This study provides an economic comparison of two processes for the extraction of lithium from zinnwaldite concentrate, a lithium mineral that can be found along the Czech/German border at Cínovec/Zinnwald. In contrast to the state‐of‐the‐art lithium extraction from siliceous ores, which is a hydrometallurgical extraction process with sulfuric acid, the novel direct‐carbonation process is based on digestion using supercritical carbon dioxide. An assessment of the capital and operating expenditures was also carried out.

Geochemical Constraints on the Origin of Banded Iron Formation‐Hosted Iron Ore from the Archaean Ntem Complex (Congo Craton) in the Meyomessi Area, Southern Cameroon

AbstractBanded iron formations (BIFs) are the most significant source of iron in the world. In this study, we report petrographic and geochemical data of the BIF from the Meyomessi area in the Ntem Complex, southern Cameroon, and discuss their genesis and the iron enrichment process. Field investigations and petrography have revealed that the studied BIF samples are hard; compact; weakly weathered; and composed of magnetite, subordinate quartz, and geothite. The geochemical composition of the whole rock reveals that iron and silica represent more than 98 wt% of the average composition, whereas Al2O3, TiO2, and high‐field strength elements (HFSE) contents are very low, similar to detritus‐free marine chemical precipitates. The total iron (TFe) contents range from 48.71 to 65.32 wt % (average of 53.29 wt %) and, together with the low concentrations of deleterious elements (0.19 wt % P on average), are consistent with medium‐grade iron ores by global standards. This interpretation is confirmed by the SiO2/Fe2O3total versus (MgO + CaO + MnO)/Fe2O3total discrimination plot in which most of the Meyomessi BIF samples fall in the field of medium‐grade siliceous ore. Only one sample (MGT94) plots in the high‐grade magnetite–geothite ore domain. The high Fe/Ti (376.36), Fe/Al (99.90), and Si/Al (29.26) ratios of the sample are consistent with significant hydrothermal components. The rare earth elements (REE) contents of the studied BIF samples are very low (∑REE: 0.81–1.47 ppm), and the Post‐Archaean Australian Shale (PAAS)‐normalized patterns display weak positive Eu anomalies (Eu/Eu*: 1.15–1.33), suggesting a syngenetic low‐temperature hydrothermal solutions, similar to other BIF worldwide. However, the Meyomessi BIFs show high Fe contents when compared to the other BIFs. This indicates an epigenetic mineralization process affected the Meyomessi BIF. From the above results and based on the field and analytical data, we propose that the genetic model of iron ores at the Meyomessi area involves two stages of the enrichment process, hypogene enrichment of BIF protore by metamorphic and magmatic fluids followed by supergene alteration as indicated by the presence of goethite in the rocks.

Applied research of shaking table for scandium concentration from a silicate ore

A poor magnetite iron ore is a super large independent scandium deposit with over the multi-billion potential utilizable value. Shaking table separation is very useful for impurities removing and scandium content increasing as a follow-up step of high-intensity magnetic separation. In the present study, a satisfactory index, namely scandium content of 83.10 g/t and recovery rate of 79.45 wt%, was obtained by shaking table separation. The good result was achieved under the conditions which the parameters were feed concentrate of 18 wt%, feeding quantity of 11 L/min, stroke frequency of 275 times/min and stroke of 17mm.

Heterogeneous catalytic ozonation of ciprofloxacin in aqueous solution using a manganese-modified silicate ore.

Manganese modified silicate ore (MnSO) prepared using an impregnation method was used as a heterogeneous ozonation catalyst, and the catalytic activity was evaluated by the degradation of ciprofloxacin (CIP). The results showed that the manganese oxide was successfully loaded onto natural silicate ore (SO). The degradation and mineralization efficiencies of CIP were considerably improved in the presence of MnSO. Under optimal conditions, the CIP removal process followed the pseudo-first-order reaction model well. The degradation rate constant of MnSO/O3 was 1.7 times and 3.3 times higher than those of SO/O3 and only O3, respectively. During the ozonation of the CIP aqueous solution in the presence of MnSO, the TOC removal rate reached 61.2% at 60 min, but was only 30.8% using ozonation alone. The addition of tert-butanol (TBA) significantly inhibited the degradation efficiency of CIP, which indicated that catalytic ozonation of MnSO followed a hydroxyl radical (·OH) reaction mechanism. Furthermore, MnSO showed great stability and durability over several reaction cycles.

Study of catalytic ozonation for tetracycline hydrochloride degradation in water by silicate ore supported Co3O4.

Tetracycline hydrochloride (TCH) degradation by cobalt modified silicate ore (CoSO) catalytic ozonation in aqueous solution was investigated. CoSO catalyst was synthesized by an impregnation method using Co(NO3)2 as the precursor and natural silicon ore (SO) as the support. The key catalyst preparation conditions (i.e., impregnation concentration, calcination temperature and time) were optimized. The activity and stability of CoSO catalyst and its catalytic ozonation mechanism for TCH degradation were studied. The results showed that Co3O4 was successfully coated on the silicon ore and the CoSO catalyst was highly efficient in catalytic ozonation for TCH degradation. The TCH removal by CoSO/O3 could reach 93.2%, while only 69.3% by SO/O3 and only 46.0% by O3 alone at 25 min. The reaction of TCH degradation followed pseudo-first order kinetics. TOC removal rate by CoSO/O3 was 2.0 times higher than that by SO/O3, and 3.5 times higher than that by O3 alone. The reaction conditions (TCH initial concentration, catalyst concentration, pH and temperature) for catalytic ozonation were systematically investigated. The possible mechanism for the CoSO catalytic ozonation process was proposed, where hydroxyl radical oxidation mainly accounted for the substantial TCH degradation. Furthermore, CoSO showed great durability and stability after seven reaction cycles.

Mineralogical characterization using QEMSCAN® and leaching potential study of REE within silicate ores: A case study of the Matamec project, Québec, Canada

The mineralogy and leachability of the rare earth elements (REE) from the Kipawa deposit, a Heavy REE (HREE) mine project of Matamec Resources (Quebec, Canada), was investigated in order to predict their geochemical behavior and to evaluate the factors controlling the REE mobility in ambient conditions. All deposit lithologies defined, including ore and waste rocks, were sampled, characterized using a mineralogical multi-technique approach (automated SEM-EDS, EPMA-WDS, XRD), and then submitted to kinetic testing using weathering cells to investigate REE release potential. The mineralogical characterization shows that REE bearing minerals are mainly represented by mosandrite, fluorbritholite, apatite, monazite and Zr silicates (i.e., aqualite, reidite). Mineralogical analysis indicates that REE particles are at least 70% liberated and the remaining portion (around 30%) is locked within gangue minerals, containing 100% REE by area. The remaining fraction is either partially or totally locked in gangue minerals (i.e. carbonates, amphibole/pyroxene, and micas). The degree of liberation of these minerals is directly linked to their weathering. All kinetic test leachates showed a neutral to alkaline pH (7.0 to 9.5) and alkalinity values between 10 and 173mgCaCO3/l. REE release from the materials are all below 15μg/l. Thermodynamic equilibrium calculations using VminteQ shows the possibility of secondary mineral precipitation (i.e. iron oxide and clays), which could be sorbed and/or co-precipitated the leached REE.