Mixture Of Quartz Research Articles

Unveiling the Bluish Green Chalcedony Aquaprase™—The Study of Its Microstructure and Mineralogy

A bluish green chalcedony (a micro to crypto polycrystalline form of silica) from Africa has been marketed with the trademark AQUAPRASETM. A multimethodological approach, combining gemological analyses, thin section examination, scanning electron microscopy, X-ray powder diffraction, Raman spectroscopy, and trace elements chemical analyses by LA–ICP–MS, was carried out to characterize this material from a gemological and mineralogical point of view. The chalcedony samples consist of a mixture of quartz and moganite, as shown by the X-ray powder diffraction analysis and Raman spectroscopy. “Aquaprase” showed a strong microstructural zoning in terms of grain size, from macrocrystalline to micro and crypto, and morphology. Trace element variations correlated well with the different colored areas of the samples. In particular, the main chromophore ion present in the bluish green areas of the “aquaprase” chalcedony was chromium, followed by iron and nickel, so this chalcedony could be included in the group of chromium-bearing chalcedony. Rayleigh light scattering contributed to the blue hue of the gems.

Vitreous silica supported metal catalysts for direct non-oxidative methane coupling

Direct non-oxidative methane coupling (NMC) transforms methane into valuable chemicals and hydrogen, which is a promising pathway to boost industrial decarbonization. The reaction, however, is challenged by high C-H bond activation temperature, catalyst coking, and low selectivity towards hydrocarbon products. Here we studied the efficacy of five vitreous silica supported 3d transition metal (Mn, Fe, Co, Ni, and Cu) catalysts (denoted as M/SiO2-v) for NMC. These catalysts were prepared by flame fusion of mixtures of quartz and metal silicate precursors. The metal species in the as-synthesized catalysts were fully or partially oxidized, with their stability following the order of Mn > Fe ≈ Co > Ni > Cu in the NMC reaction. The Cu species has low methane reaction rate, due to the high adsorption and dissociation energies of methane. The Mn and Ni species have high methane reaction and coke formation rates, which is supported by easy kinetics of methane deep dehydrogenation to carbon. In contrast, Fe and Co species showed the best hydrocarbon product selectivity. Particularly, the Co species emerged as the optimal catalyst for NMC, showcasing a balanced methane activation, hydrocarbon formation, and low coke yield. The relationship between the evolved metal species under reaction conditions and their NMC performance was discussed. The present study screens and provides effective catalyst formulations for NMC reactions.

Assessment of mineral compositions on geo-mechanical time dependent plastic creep deformation

Understanding rock mechanical time-dependent plastic deformation enables the researchers to accurately predict rock responses during loading and unloading. This research focuses on the geomechanical aspects of hydrogen storage, particularly rock resistance to creep deformation under varying stresses and pressures. Modelling creep deformation in underground storage mediums has been overlooked and requires further consideration, as it is a critical, cyclical, time-dependent phenomenon essential for hydrogen containment. The study's novelty is demonstrated in its focus on geomechanical properties of rock minerals, providing insights that aid in site-selection criteria for hydrogen storage A creep deformation model with varying mineral compositions is used to assess creep deformation strain. In homogenous cases, calcite showed the highest resistance to creep deformation after three loading cycles, primarily due to its high Young's Modulus. As for the heterogenous cases, the results indicated that the mixture of calcite and quartz was the most creep-resistant rock composition. In terms of rock types, basalt samples demonstrated the highest resistance to creep deformation, while siltstone exhibited the highest susceptibility to deformation. It was observed that as the number of cycles increase, the rock mechanical stability decreases, hence optimizing the number of cycles is a must to ensure hydrogen geo-containment.

On Liangzhu Culture Tremolite-Tempered Pottery: Social complexity, logistical networks and cross-craft interaction in Neolithic China

This investigation delves into the utilization of tremolite, a rare mineral, as a pottery temper for cooking vessels of the late Neolithic lower Yangtze Liangzhu culture. Raman spectroscopy analysis of 165 mineral-tempered pottery sherds from the Dazemiao site revealed that tremolite was the predominant tempering material for tripods (ding), whereas a mixture of feldspar and quartz was used for open-topped vats (da-kou-gang). SEM images indicate that the tremolite temper exhibits relatively coarse fiber structure, corresponding to one of the nephrite materials used for the Liangzhu jade. It is suggested that the Liangzhu miners reallocated materials according to nephrite quality, formulating different product lines, including different types of jade objects and pottery temper. Additionally, the utilization of tremolite temper persisted throughout the entire Liangzhu culture. The presence of tremolite-tempered pottery in regions without indigenous tremolite mines necessitated robust logistical networks for the transportation of these bulky materials. The tremolite temper not only reconfirms the strong ‘jade culture’ of Liangzhu, but also provides evidence of extensive socio-economic exchanges between different geographical regions on the Yangtze River delta.

Selective aggregation of fine copper minerals using charged polyacrylamides

Selective aggregation can be used to improve the collection of fine valuable mineral particles often lost in industrial separation processes. This approach might be applicable to flocculate fine copper mineral particles such as chalcopyrite. It is hypothesised that the polymeric flocculant charge type will influence selectivity between chalcopyrite and waste minerals. This work investigates the use of charged anionic (APAM) and cationic (CPAM) polyacrylamides to selectively aggregate negatively charged chalcopyrite from its common waste (quartz). The interaction of the polymers with the mineral's surfaces as well as its flocculation capability were investigated through adsorption isotherms, turbidity tests, and in-situ aggregate size measurement. Furthermore, the ability to selectively aggregate and recover the valuable chalcopyrite from a quartz mixture by sedimentation was assessed. The results indicated that both charged polymers can be used to aggregate fine chalcopyrite particles, however, CPAM is non-selective towards the valuable mineral, as it also aggregates quartz. CPAM has a stronger affinity for both minerals, probably due to charge-charge interaction adsorption mechanisms, whereas APAM adsorption was lower, and more likely to be driven by hydrogen bonding. The interaction of APAM with quartz was limited probably because its highly negatively charged surface tends to repel the anionic polymer. Finally, the recovery of the chalcopyrite by sedimentation separation improved when using both polymers, but higher recoveries were obtained when using APAM.

Prediction of the mineral components spatial distribution in tailings ferruginous quartzite enrichments

In Ukraine, a significant mass of potential man-made deposits is represented by waste from ferruginous quartzite enrichment. The mineral mass of such deposits is mixture of iron-containing minerals (magnetite, ilmenite) and quartz. The M.S. Poliakov Institute of Geotechnical Mechanics has developed a new methodology for the mineral components spatial distribution predicting in tailings of ferruginous quartzite enrichment. It includes the fractional and mineralogical composition of the samples study by optical method, and spatial useful components distribution of prognostication in waste and predictive plans construction for the useful components spatial placement. A previously unknown pattern of changes in mineral composition of wastes from mining ore production was revealed which caused by the turbulent transportation mode and waste deposition on the tailing (potential man-made deposit) area. This regularity arises from the fact that with decrease in the size of the mineral components particles with size of 0-200 microns, the share of the magnetic mineral magnetite increases linearly and, accordingly, the share of the non-magnetic mineral quartz decreases. The obtained new properties of man-made deposits from the waste (tailings) can be used in creation of resource-saving technology for the iron ore man-made raw materials processing and to determine their suitability for mining.

Transient and Steady‐State Friction in Non‐Isobaric Conditions

AbstractThe frictional properties of faults control the initiation and propagation of earthquakes and the associated hazards. Although the ambient temperature and instantaneous slip velocity controls on friction in isobaric conditions are increasingly well understood, the role of normal stress on steady‐state and transient frictional behaviors remains elusive. The friction coefficient of rocks exhibits a strong dependence on normal stress at typical crustal depths. Furthermore, rapid changes in normal stress cause a direct effect on friction followed by an evolutionary response. Here, we derive a constitutive friction law that consistently explains the yield strength of rocks from atmospheric pressure to gigapascals while capturing the transient behavior following perturbations in normal stress. The model explains the frictional strength of a variety of sedimentary, metamorphic, and igneous rocks and the slip‐dependent response upon normal stress steps of Westerly granite bare contact and synthetic gouges made of quartz and a mixture of quartz and smectite. The nonlinear normal stress dependence of the frictional resistance may originate from the distribution of asperities that control the real area of contact. The direct and transient effects may be important for induced seismicity by hydraulic fracturing or for naturally occurring normal stress perturbations within fault zones in the brittle crust.

Pyrolysis of Polyethylene from Plastic Waste using Activated Ende Natural Zeolite as a Catalyst

Plastic waste has many complex chemical components. In developing countries, direct incineration is often used to reduce plastic waste, releasing pollutants into the atmosphere. A more environmentally sound alternative is pyrolysis. It can turn plastic waste into an alternative fuel. A catalyst, such as natural zeolite, can reduce the energy used in pyrolysis. However, mineral contaminants must be removed first to get optimum activity. This research was focused on using Ende natural zeolite as a catalyst, determining the properties of the mineral in its activated form. It also investigated the interaction between H-zeolite composition and the operating temperature towards pyrolysis oil yield. The experimental results showed that Ende natural zeolite contained a mixture of mordenite, clinoptilolite, and quartz. After activation and modification, there was an increase in the surface area from 53.17–104.67 m2/g. The average pore radius ranged from 19.96–34.21 Å. There was an increase in the pore volume from 22.01–72.34 cc/g. The total acidity changed from 1.456–5.342 NH3/g. The optimum catalyst concentration was 10% in the pyrolysis of 1000 grams of plastic waste catalyzed by 100 grams of H-zeolite. The oil yield decreased at 15% concentration. The 10% concentration worked best at 400 ℃.

Ceramic floor tiles with yellow pigment from Kievan Rus’: A technological study

Colored glazed ceramic tiles were widely used for paving floors of the main buildings, mostly Orthodox churches, in the Kievan Rus’ (10th-13th centuries AD). The production of ceramic floor tiles was localized near the site of construction, and the date of production can be attributed to the date of construction or renovation of the church. Therefore, the study of glazed tiles makes it possible to determine the local and chronological features of their production technology.. Local production technology in Ancient Rus' was studied using thirteen yellow glazed ceramic tiles from six cities (Kiev, Galich, Polotsk, Vladimir-Volynsky, Pereslavl-Zalessky and Novgorod). Also, two samples were selected from churches in Polotsk, Vladimir-Volynsky and Vyshgorod at different times of construction or renovation to study chronological variations in tile production technology. Chemical compositions and crystalline phases of yellow glaze and ceramic body have been analyzed by X-ray diffraction, Raman and X-ray fluorescence spectroscopy. In all cases, samples of ceramic tiles were glazed with high-lead silicate glass, and lead tin yellow type II (PbSn1-xSixO3) was used as a pigment. Local production technology in Ancient Rus' was studied using thirteen yellow glazed ceramic tiles from six cities (Kiev, Galich, Polotsk, Vladimir-Volynsky, Pereslavl-Zalessky and Novgorod). Also, two samples were selected from churches in Polotsk, Vladimir-Volynsky and Vyshgorod at different times of construction or renovation to study chronological variations in tile production technology. Most likely, the glaze layer on the ceramic tile was formed using pre-synthesized glass; this technology differs from the conventional technology for pottery, uses lead oxide or a mixture of lead oxide and quartz. Data on the chemical composition of yellow lead glazed tiles dating from the 10th-13th centuries AD can be used to determine the region of glazed ceramic production.

Fabrication and characterization of the novel tubular ceramic membrane using walnut shells and its application in TiO2 nanoparticles separation from suspension

Low-cost ceramic membranes have become highly popular in water treatment and gas separation industries. This study focuses on creating an affordable yet efficient ceramic membrane for effective separation processes. The cost-effective fabrication process combines locally sourced raw materials with optimal manufacturing techniques, resulting in minimal production expenses. To create this unique, low-cost ceramic membrane, a mixture of kaolin, quartz, and additives like zirconia and dolomite is used in shaping and sintering procedures. Walnut shell powder serves as a pore-forming agent, while carmellose sodium acts as a membrane-binding agent. The membrane is prepared through extrusion with dimensions of 110 mm in length and 12 mm in diameter, and it is sintered at temperatures of 850 °C, 900 °C, and 950 °C. Various analytical methods, including FESEM, XRD, and TGA, are employed for comprehensive characterization. The water flux increased with increasing pressure (54–215 kPa), and the pore diameter obtained from the test was consistent with the pore size obtained from FESEM. The membranes' pore size increases with higher sintering temperatures while porosity decreases. The membrane demonstrates mechanical strength, chemical stability, and high rejection efficiency in TiO2 separation. The total cost of one tubular membrane comes out to be $112 per square meter.

Geochemical study on the deposition of silica scale at Olkaria well OW-35: A key to understanding the formation mechanisms of silica scale at the Olkaria Geothermal Field, Kenya

In the Olkaria geothermal field, Kenya, a silica scale formed from geothermal water at the OW-35 production well was geochemically investigated. The geothermal water is highly alkaline, with a pH of 10.13, while the salinity is low, with a total Cl concentration of 432.4 ppm. The silica scale was precipitated from geothermal water with a high temperature (150–190 °C) in the OW-35 separator. For the mineral composition of the scale sample, it is mainly amorphous Opal-A and crystalline quartz. The SiO2 content was 85.47 wt.%, and the Al2O3 and Fe2O3 contents were high at 3.16 and 1.11%, respectively, despite the fact that Al and Fe concentrations in the geothermal water were low. Based on the enrichment factor, Al was extremely concentrated from the geothermal water onto the silica scale during the formation, suggesting that Al may participate in the formation of the silica scale. For Fe, there was no contribution of Fe to the formation of silica scale, which was present as magnetite. This silica scale is a mixture of crystalline quartz and amorphous opal-A. The deposition mechanism was considered as follows. The quartz was formed by continuous and slow adsorption of monosilicic acid on the surface of the solid due to the slight supersaturated condition. On the other hand, opal-A was formed by a reaction between aluminate ion and monosilicic acid or monosilicate ion on the solid surface.

Isotopic (δ13C, δ18O) Analysis of Small Amounts of Carbonate in Silicate Rocks by the Continuous Flow Isotope Ratio Mass Spectrometry Method

An experimental study of the main factors affecting the accuracy of oxygen and carbon isotopic analysis in carbonates dispersed in silicate matrix is carried out. Artificial 1, 2, 5, and 10% mixtures of quartz with carbonates with different isotopic parameters (KH-2, Ko, MCA-8) were analyzed by continuous flow isotope ratio mass spectrometry (CF IRMS). It is established that, in addition to the influence of the instrumental nonlinearity, the results are affected by two factors: trace amounts of CO2, constantly present in the system (the blank effect) and the presence of chemically neutral silicate particles (the matrix effect). The blank effect depends on the isotopic parameters of the sample and has very little influence on the estimated carbonate content in the rock. The matrix effect, on the contrary, strongly affects the estimated carbonate content, and produces the isotopic shift towards underestimated contents of heavy 13C and 18O isotopes. It is shown that this effect is related to the processes occurring near the CO2–acid–quartz interface, which are accompanied by kinetic fractionation of carbon and oxygen isotopes. Both effects are dependent on the amount of silicate matrix in the system and most clearly manifested during analysis of carbonate-poor rocks. When the carbonate content in the rock is about 1–2%, deviations from the true δ13C and δ18O values can reach the first ppm, while carbonate content obtained by chromatographic peak calibration can be underestimated by 20–40%.

Isotopic (δ13C, δ18O) Analysis of Small Amounts of Carbonate in Silicate Rocks by the Continuous Flow Isotope Ratio Mass Spectrometry Method

An experimental study of the main factors affecting the accuracy of oxygen and carbon isotopic analysis in carbonates dispersed in silicate matrix is carried out. Artificial 1, 2, 5, and 10% mixtures of quartz with carbonates with different isotopic parameters (KH-2, Ko, MCA-8) were analyzed by continuous flow isotope ratio mass spectrometry (CF IRMS). It is established that, in addition to the influence of the instrumental nonlinearity, the results are affected by two factors: trace amounts of CO2, constantly present in the system (the blank effect) and the presence of chemically neutral silicate particles (the matrix effect). The blank effect depends on the isotopic parameters of the sample and has very little influence on the estimated carbonate content in the rock. The matrix effect, on the contrary, strongly affects the estimated carbonate content, and produces the isotopic shift towards underestimated contents of heavy 13C and 18O isotopes. It is shown that this effect is related to the processes occurring near the CO2–acid–quartz interface, which are accompanied by kinetic fractionation of carbon and oxygen isotopes. Both effects are dependent on the amount of silicate matrix in the system and most clearly manifested during analysis of carbonate-poor rocks. When the carbonate content in the rock is about 1–2%, deviations from the true δ13C and δ18O values can reach the first ppm, while carbonate content obtained by chromatographic peak calibration can be underestimated by 20–40%.

The Role of Clay in Limiting Frictional Healing in Fault Gouges

AbstractFrictional healing is fundamental to the seismic cycle and plays a role in the energy balance, dynamics, and recurrence interval of earthquakes and slow slip events. Although the healing behavior of quartz has been studied extensively, the role of clay content is less understood. We tested synthetic mixtures of quartz and smectite (10%–100% smectite) in a double‐direct shear configuration to measure frictional healing. We show that the magnitude and rate of healing decreases systematically with higher clay content (from 0.008/decade at 10% smectite to 0.002/decade at 100% smectite). Healing scales with both the magnitude of stress relaxation during holds and layer‐normal compaction of the gouge. We suggest this reflects the alignment of clay minerals, leading to saturation of the real area of contact that limits restrengthening during holds. The low healing rates of clay‐rich faults—together with rate‐neutral to rate‐strengthening friction—should promote frequent, small failures or stable sliding.

Effects of agitation intensity and foam stability on the Floc-flotation of ultrafine minerals using a laboratory flotation column

In the present study flocculation flotation (floc-flotation) of ultrafine hematite and quartz was investigated in a laboratory-scale flotation column. A direct flotation scheme was used to float hematite using in-house synthesized n-octyl hydroxamic acid (OHA) as a collector. A polymer system containing tannic acid (TAN) and poly(ethylene oxide) (PEO) was used to flocculate quartz to reduce its entrainment. The effects of agitation intensity and foam stability on floc size distribution, entrainment reduction, and flotation kinetics/recovery were investigated. It was shown that the dual polymers TAN-PEO were effective in reducing quartz entrainment, and that the degree of entrainment reduction was affected by the intensity of agitation. A correlation was established between the mean floc size and a reduction in quartz entrainment. TAN-PEO dual polymer system also enhanced the flotation kinetics and recovery of hematite by OHA, originating from a synergistic effect between PEO and OHA. Therefore, higher separation efficiency was achieved from synthetic ultrafine hematite and quartz mixtures when TAN-PEO was added after OHA. The underlying mechanisms were studied by floc size distribution, surface tension, and foam height and decay time measurement. This work helps understand the relationship between hydrodynamic condition, flocs size, and mechanical entrainment when polymeric flocculation is used for entrainment reduction in fine and ultrafine minerals flotation.

Deciphering the origin(s) of H and Cl in Apollo 15 quartz monzodiorites: Evidence for multiple processes and reservoirs

Apollo 15 quartz monzodiorites (QMDs) are reported to contain some of the most deuterium-depleted apatite found in lunar samples. In this study, apatite from six Apollo 15 QMDs, including three samples from 15405 not previously investigated, were analyzed for their H and Cl isotopes. Apatite in 15405 are extremely 2H (or D)-poor, with δD values ranging from −658 ± 53 to −378 ± 113‰, comparable to apatite data from related samples 15403 and 15404. In addition to new H isotope data, the first Cl-isotope data for lunar QMDs are presented. Apatite in 15405 and related samples are enriched in 37Cl with respect to Earth, with measured δ37Cl values ranging from +13 to +37‰. These values are within the reported δ37Cl range for KREEP-rich samples. The fact that the Cl isotopic composition of apatite in QMDs are similar to those in other lunar lithologies, but the H isotopic data are distinct and unique, provides possible further evidence for the existence of a D-poor reservoir in the lunar interior. Raman spectroscopy of the silica polymorph in sample 15405 reveals it to be a mixture of quartz and cristobalite. Based on available experimental data on the stability of various silica phases over a range of pressure and temperature regime, a deep-seated origin in the crust for QMDs may be possible which would support an endogenous origin of the H-Cl isotope systematics of the QMDs. The role of impact-induced transformation of silica phases and its contributing towards low D/H ratio in apatite, however, cannot be ruled out.

An investigation into the dry processing of low specific gravity ores using a laboratory Knelson concentrator

ABSTRACT The Knelson concentrator (KC) was originally invented and developed for treating gold ores, and due to its high efficiency, low cost and minor environmental impact, it has become an active research area for processing low specific gravity (SG) deposits. The laboratory scale KC has shown its potential for processing high-density ores on a dry basis. This work investigated the feasibility and the optimum operating conditions when processing a dry low SG feed with a modified KC. A synthetic mixture of magnetite (SG 5.2) and quartz (SG 2.65) with a grade of 1% magnetite and three synthetic mixtures of magnetite and quartz with a grade of 5% magnetite in different sizes were used to mimic a low-density ratio ore. Central composite design (CCD) and response surface method (RSM) were used to design the experiments and optimise each process. The effects of each individual factors and their interactions on concentrate grade and magnetite recovery were evaluated for each feed. Optimum operating conditions were obtained at a bowl speed, solids feed rate and air fluidising pressure of 20G, 100 g/min and 12 psi, for 1% grade feed; 14, 300 g/min and 13 psi, for 5% coarse feed; 18 G, 300 g/min and 13 psi, for 5% intermediate feed; and 10 G, 100 g/min and 14 psi for 5% full-size feed.

Deformation mechanisms and rheology inversion of jointly deformed marble and quartzite in natural thermal gradient

Amphibolite facies marble surrounded by locally pure but mostly impure quartzite with ∼10–14% of dispersed white mica and crosscut by granite veins were jointly deformed within an extensional shear zone. Both marble and quartzite show three microstructural stages, M1m-M3m and M1q-M3qm, respectively, correlated with the onset of extension Stage 1 at ∼600 °C, and retrograde extension Stage 2 at ∼380 °C and Stage 3 at ∼300 °C. The coarse-grained microstructures M1m (1200 μm) in marble and M1q (300 μm) in pure quartzite showed the activity of basal ⟨a⟩ slip and prism ⟨a⟩ − rhomb ⟨a⟩ slip, respectively. The finer grained M2m (∼50 μm) microstructure in marble is associated with strain localization, subgrain rotation recrystallization and persistence of basal ⟨a⟩ slip. The M2q (175 μm) microstructure in pure quartzite shows a crossed girdle c-axis pattern, while the M2qm (120 μm) in impure quartzite shows locally c-axes parallel to the lineation, indicating the possible activity of prism [c] slip. Stage 3 in marble is characterised by minor recrystallization M3m that occurs mostly along microcracks formed subparallel to foliation. The impure quartzite M3qm microstructure shows further reduction in quartz grain size (80–90 μm) related to pining of well-dispersed white mica. The microstructure M1m-M1q and M2m-M2q formed by dislocation creep, while the M2qm and M3qm suggest the Rachinger grain boundary sliding of quartz grains along micas. Piezometric calculations suggest differential stresses of 1–5 MPa and ∼20 MPa for the M1m and M2m microstructures and 7 MPa and 11 MPa for the M1q and M2q microstructures, respectively. Comparison of these data with experimental flow laws confirmed that during Stage 1 marble is weaker than quartzite. However, during Stages 2 and 3, mica in impure quartzite became more dispersed but also locally aggregated; thus, the bulk strength of quartzite became governed by mixture of quartz and weak mica behaviour. This change in microstructure and the resulting deformation mechanism facilitated fluid transport across quartzite, which resulted in embrittlement of dominantly coarse-grained and impermeable competent marble. This process is accompanied by the formation of stretching faults developed parallel to weak layers of altered granite dykes in the vicinity of the marble-quartzite contact. The rheology inversion thus results from a mixture of deformation mechanisms in the weak polyphase quartzite and fluid-induced drop of effective pressure of strong and brittle marble at late stages of the extensional deformation.

Green hematite depression for reverse selective flotation separation from quartz by locust bean gum

Reverse cationic flotation is currently the main processing technique for upgrading fine hematite from silicates. Flotation is known as an efficient method of mineral enrichment that deals with possibly hazardous chemicals. Thus, using eco-friendly flotation reagents for such a process is an emerging need for sustainable development and green transition. As an innovative approach, this investigation explored the potential of locust bean gum (LBG) as a biodegradable depressant for the selective separation of fine hematite from quartz through reverse cationic flotation. Various flotation conditions (micro and batch flotation) were conducted, and the mechanisms of LBG adsorption have been examined by different analyses (contact angle measurement, surface adsorption, zeta potential measurements, and FT-IR analysis). The micro flotation outcome indicated that the LBG could selectively depress hematite particles with negligible effect on quartz floatability. Flotation of mixed minerals (hematite and quartz mixture in various ratios) indicated that LGB could enhance separation efficiency (hematite recovery > 88%). Outcomes of the surface wettability indicated that even in the presence of the collector (dodecylamine), LBG decreased the hematite work of adhesion and had a slight effect on quartz. The LBG adsorbed selectively by hydrogen bonding on the surface of hematite based on various surface analyses.

A preliminary investigation of dry gravity separation with low specific gravity ores using a laboratory Knelson Concentrator

It has become an active research area for treating low specific gravity (SG) deposits by centrifugal separation due to its high efficiency, low cost and minor environmental impact. Laboratory Knelson Concentrator has shown its potential for processing high density ores on a dry basis. This study investigated the feasibility and the optimum operating conditions when processing a dry low SG feed with a modified Knelson Concentrator. A synthetic mixture of magnetite and quartz with a grade of 1% magnetite was used to mimic a low-density ratio ore. Bowl speed (G), air fluidizing pressure (psi) and solids feed rate (g/min) were chosen as the operating variables. Box-Behnken design was used to design the experiments and response surface method was used for optimization. The effects of each individual factors and their interactions on concentrate grade and magnetite recovery were evaluated. The dry process achieved up to 60 % magnetite recovery with an upgrade ratio of 5. The optimized values for the concentration with the highest recovery and grade of bowl speed, solids feed rate and air fluidizing pressure are 27 G, 200 g/min and 12 psi, respectively.