Mesh Size Fraction Research Articles

The Effect of Aloe Vera Bioreagent as a Frother and Collector in the Gold Ore Flotation Process on Increasing Grade and Recovery

One of the concentration processes in processing sulfide gold ore is the flotation technique which takes advantage of differences in mineral surface properties by adding chemical reagents. The addition of chemical reagents to the flotation process can cause environmental problems. Therefore, efforts are needed to replace chemical reagents with more environmentally friendly materials. In this research, an attempt was made to replace chemical reagents with a commonly found plant extract, namely aloe vera, as a bioreagent. Bioflotation experiments on a laboratory scale were carried out using a Denver flotation cell with an aloe vera reagent as a frother. This gold mineral bioflotation experiment was carried out on a 150 mesh size fraction. The results of increasing concentrate levels by flotation indicate that the aloe vera reagent as a frother is able to produce biosurfactants which replace chemical reagents as a more environmentally friendly biofrother and biocollector. This can be concluded based on flotation experiment data with bioreagent which has been tested showing an Au content value of 10.09 and a recovery of 96.15%, while flotation using chemical reagents shows an Au content value of 10.50 and a recovery of 95.96%. So the use of aloe vera as an environmentally friendly bioreagent in the flotation process releasing low sulfidation gold is more effective than the use of chemical reagents because it is indicated that there is a biosurfactant content in aloe vera.

INVESTIGATION OF THE EFFECT OF MESH SIZE AND FRACTION VOLUME ON BENDING STRENGTH CHARACTERISTICS OF GEOPOLYMER COMPOSITE

Composite material is a material consisting of two or more type materials that have different properties, by combining macroscopically, and good interfacial bonds from one material to another. Currently, polymer composite materials are widely applied in the land, sea, and air transportation industries, moreover polymer composites with fire resistance properties have been developed with the addition of geopolymer that has the advantage of producing high performance. This study aims to determine the effect of mesh size and volume fraction of lightweight brick powder on flexural strength. The benefits of this research directly increase the economic value of lightweight brick waste and produce a tough advanced material at a low cost. The composite filling material used lightweight brick waste and sieved using a sieve with a level of 50, 100, 150, and 200 at a volume fraction of 45%, and a volume fraction of 0%, 15%, 30%, 45%, and 60% at a mesh 200. While the composite matrix used the thermoset polymer Ripoxy R-804. Based the result, addition of lightweight brick powder with variations in particle size of the lightweight brick powder and volume fraction showed a decrease in flexural strength resistance compared to those without lightweight brick powder.

An XFEM‐strain gradient damage model for efficient modeling of materials with reinforcement particles

A coupling of extended finite element method (XFEM) and strain gradient enhanced damage method is proposed to model damage initiation and growth in the materials with reinforcement particles. The proposed model inherits the advantages of both methods i.e., simple definition of reinforcement particles from XFEM and numerical stability during damage evolution from the strain gradient damage model. The capability of the proposed XFEM-strain gradient damage model has been demonstrated by simulating mode-I, mode-II, and the mix-mode failure mechanism in the SENB, SEN, and L-shaped specimen with reinforcement particles respectively. The numerical simulations are performed by considering hard and soft reinforcement particles in a matrix. Mesh-sensitivity and particle-sensitivity analysis are performed to quantify effect of various parameters like mesh size, particle size and volume fraction on behavior of SENB specimen. The proposed XFEM model is at least 10% efficient (at higher mesh densities) than the standard FEM model for solving the SENB specimen with reinforcement particles. In the particle sensitivity analysis, proposed XFEM model used only one mesh density (unlike FEM model that needs different conformal meshes) to simulate set of 400 realizations with random spatial distribution of reinforcement particles. The analysis shows that the computational demand for the creation of conformal mesh is alleviated with the use of XFEM for defining reinforcement particles. The mesh-sensitivity analysis shows that difference in the solution obtained using proposed XFEM model and standard FEM model is negligible (less than 1% at higher mesh densities). Therefore, the proposed XFEM-strain gradient damage model can substitute FEM-strain gradient damage model with above mentioned efficiencies.

Prediction of surface finish in extrusion honing process by regression analysis and artificial neural networks

The current work explores the influence of process parameters such as mesh size and volume fraction of abrasives with number of passes, on the interior surface quality of a pre machined component by extrusion honing process. The finishing process is highly flexible and unconventional while modifying the surfaces in case of miniature components involving complex profiles. The method is extensively used to deburr, polish, edge contour and removing recast layers by producing compressive stresses. By, the pressurized flow of semi viscous abrasive laden across the surface to be processed. The experimental study has been carried out on Inconel-625 alloy by one way EH process, with the carrier medium silicone polymer blended with SiC as abrasives. Experiments are planned by constructing L27 orthogonal array for the factors such as mesh number 36, 46, 54 and volume fraction 40, 50, 60 % of abrasives followed by number of passes 5, 10 and 15. Also, the study focuses in developing a regression model, training neural network and comparison of experimental Ra with both regression and ANN model. The prediction of Ra is accomplished by developing a linear regression model and a feed forward back propagation neural network model. Both the developed models are able to predict the output response with an error of 5 to 12%.

Exploration for strategic placer mineral deposits in a fluctuating shoreline: Depositional environment and mineralogical characterization of the NE Odisha coast placers, India

Systematic exploration for beach placer minerals has been undertaken in the Chandipur area of the Balasore district on the NE Odisha coast of India. Beach and dune sands are ubiquitous along the 1–1.5 km-wide NNE-trending coast. Forty-three representative samples were collected from selected boreholes sampled by auger and dormer drilling at depths ranging from 6.0 m to 12.0 m. Detailed experimental studies show that the total heavy minerals (THM) grade of the study area varies from 0.4 to 11.2% with an average grade of 3.8% for the individual samples; the upper 5.50 m sand column with a grade of 5.2% is most significant. The heavy mineral assemblages, in decreasing volumetric percentages, are comprised of 55% ilmenite, 25% sillimanite, 11% pyriboles/others (pyroxene, amphibole, mica, coated grains etc.), 5.9% rutile, 1.5% leucoxene, 1.2% garnet, 0.5% zircon, and 0.4% magnetite. Texturally, elevated heavy mineral concentrations are drawn from +200 ASTM (+75 µm) and 120 ASTM (+125 µm) mesh size fraction; the 40 ASTM (425 µm) size fraction contains lowest THM. The overall concentration of heavy minerals shows variable distribution patterns from shore to littoral (inland), and the maximum concentration of THM is observed within the 1.5 m sandy surface horizon. The present study also addresses the down-core variation of heavy mineral assemblages and role of hydrodynamic conditions in the deposition of these wide-ranging placer minerals. The range of graphic mean sizes (Mz) varies from 2.19 to 2.60 (Φ), which corroborates the deposition of sediments in low energy condition in a fluctuating shoreline along the Chandipur coast. Linear discriminant function analysis is predominantly indicative of diversity in the depositional features under aeolian conditions in a shallow marine environment. CM and Tractive current plots indicate that the sediments are mainly formed by graded suspension and without any rolling conditions in the beach subenvironment in a tractive current field. Both the perennial (Panchpara River) and the ephemeral drainage systems (Dubdubi River) played a dominant role in transporting and supplying sediment flux consisting of radioactive mineral (monazite) assemblages in the study area. The present detailed exploration study reveals a new find of placer deposits with radioactive and non-radioactive mineral assemblages formed from diverse sources.

Parametric studies and manufacturability experiments on smooth self-supporting topologies

ABSTRACT This paper aims to explore the effects of optimisation parameters (the filter radius, mesh size, and target volume fraction) on the compliance and manufacturability of smooth self-supporting topologies for additive manufacturing (AM); and conduct manufacturability experiments of selected simulation results with the Selective Laser Melting (SLM) technology. In this study, smooth self-supporting topologies are obtained with a combined method of the Solid Isotropic Microstructure with Penalization method (SIMP) with the smooth boundary representation and Langelaar's AM filter. Numerical examples illustrate that a higher filter radius can lead to simpler smooth self-supporting topologies, but curved top corners that violate the critical overhang angle of 45° are inevitably generated. Additionally, the mesh size is found to be not as an important factor as the filter radius in affecting the manufacturability and performance. As a result of the self-supporting constraint, a small volume fraction can easily result in structural discontinuity. The experimental results demonstrate that the self-supporting topologies obtained are all printable in SLM.

Analysis of 98 individual −200 mesh iron ore samples in a single scanning electron microscope-automated mineralogy session

ABSTRACTSingle-step trans-vertical moulds have been shown to increase the throughput of automated mineralogy systems. Owing to the small particle size of iron ore grains in the −200 mesh size fraction (<75 µm), not all of the surface area on a mould is needed for measurement in achieving good statistical representation. Trimming the excess area of a mould results in superfluous material being removed, leaving only the necessary analyte. This allows maximum packing in the sample chamber and promotes efficiency by increasing the quantity of samples that can fit in a newly designed trans-vertical adapter for an FEI MLA™ 650 field emission gun SEM. The analysis was completed using a newly designed sample block holder capable of holding 98 samples. This study represents the most expedient method yet reported to prepare well-polished samples and analyse them in a timely manner that can allow for quicker results in process mineralogy.

An estimation of the variability in automated quantitative mineralogy measurements through inter-laboratory testing

Presently there are about 160 installations of automated mineralogy instruments such as QEM∗SCAN, MLA, TIMA, MINERALOGIC and INCAMineral. These instruments determine mineral quantities, and perform mineral liberation and mineral association analyses. Since the late 1990’s the scientific community of applied mineralogy and automated mineralogy has expressed the need of determining the variability in the measurements of mineral quantities and mineral liberation analyses through inter laboratory testing of suitable reference materials to improve confidence in the quantitative mineralogy measurements. A sample representing the −28+65 mesh size fraction of a sulphide flotation rougher concentrate from the Clarabelle mill in Copper Cliff, Vale (Sudbury, Ontario) was prepared for this testing. This rougher concentrate contains chalcopyrite, pyrrhotite, pentlandite, pyrite, quartz and feldspars as the dominant minerals. A 10-gram sub-sample was sent to the participating laboratories of the round robin. The sub-samples were analyzed by the participating laboratories to determine the mineral quantities, the liberation of chalcopyrite and the mineral association analysis for chalcopyrite. The findings indicate that there is a good agreement in the mineral quantities. The liberation analysis results also indicate a good agreement with the exception of two participants. These results indicate that correct mineral quantities do not necessarily imply correct mineral liberation. The testing also revealed that there was no consensus on how the mineral associations are treated and reported. We recommend that the modal analysis by liberation classes should be the preferred approach in reporting the mineral associations because it is more relevant to understand the mineral concentration operations.

A single-step trans-vertical epoxy preparation method for maximising throughput of iron-ore samples via SEM-MLA analysis

A novel approach to creating a trans-vertical grain mount embedded in epoxy has been demonstrated through the creation of a new mounting mould, as well as a polisher adapter and sample holder for the Quanta 400 SEM. These rectangular moulds result in a sample that is 30 mm long × 10 mm high × 17 mm wide, thus leading to the ability to polish 10 samples at once. Up to 14 samples may fit in the SEM holder for analysis. This represents an increase in efficiency of over 50%, and with a slow-speed polishing method, the consumables used are reduced by at least a factor of 4. This has the potential to lead to significant financial savings. A comparison of mounting techniques using a −100+200 mesh size fraction of an iron-ore sample from Labrador demonstrates that this new mounting system removes any bias in analysis resulting from density stratification during the sample preparation. These moulds yield similar modal mineralogy abundances and standard deviation as the two-step trans-vertical method, but they are less labour-intensive to make and more efficient to analyse.

Uncertainty in the Surface Area of Crushed Glass in Rate Calculations

ABSTRACTSeries of 7-day Product Consistency Tests (PCTs) were conducted with ARM-1 glass using the -100+200 mesh size fraction and several sub-fractions to measure the sensitivity of the test response to the distribution of particle sizes. Separate samples were prepared for testing by dry sieving and wet sieving, and the particle size distributions and PCT responses were measured for each fraction. Triplicate tests were conducted at 90 °C using a water/glass mass ratio of 10.0 with each size fraction. Test results are evaluated regarding the sensitivity of the test response to the particle size distributions and, conversely, the uncertainty due to calculating the surface areas (and dissolution rates) by modeling the particles as spheres. These analyses show the solution feedback effects of dissolved glass constituents (i.e., the reaction affinity) counteract the effects of the glass surface areas provided by different particle size distributions on the test response. The opposing effects of the surface area on the amount of glass dissolved and on the glass dissolution rate moderate the sensitivity of the PCT response to the particle size distribution.

Mechanical and structural response of a hybrid hydrogel based on chitosan and poly(vinyl alcohol) cross-linked with epichlorohydrin for potential use in tissue engineering

The development and characterization of a hybrid hydrogel based on chitosan (CS) and poly(vinyl alcohol) (PVA) chemically cross-linked with epichlorohydrin (ECH) is presented. The mechanical response of these hydrogels was evaluated by uniaxial tensile tests; in addition, their structural properties such as average molecular weight between cross-link points (Mcrl), mesh size (DN), and volume fraction (vs) were determined. This was done using the equivalent polymer network theory in combination with the obtained results from tensile and swelling tests. The films showed Young’s modulus values of 11 ± 2 MPa and 9 ± 1 MPa for none irradiated and ultraviolet (UV) irradiated hydrogels, respectively. The cell viability was assessed using Calcein AM and Ethidium homodimer-1 assay and environmental scanning electron microscopy. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan thiazolyl blue formazan (MTT Formazan assay) results did not show cytotoxic effects; this was in good agreement with nuclear magnetic resonance and fourier transform infrared spectroscopies; their results did not show traces of ECH. This indicated that after the crosslinking process, there was no free ECH; furthermore, any possibility of ECH release in the construct during cell culture was discarded. The CS-PVA-ECH hybrid hydrogel allowed cell growth and extracellular matrix formation and showed adequate mechanical, structural, and biological properties for potential use in tissue engineering applications.

Distribution of platinum group elements in road dust in the Beijing metropolitan area, China

Dust samples collected from the Beijing metropolitan area (China) were evaluated to determine the distribution and the concentration of platinum group elements (PGEs). The dust particles that were smaller than 100 mesh size fraction (150 μm) were analyzed after aqua regia digestion. Concentrations of Pt, Rh, and Pd were found to be between 3.96 and 356.3 ng/g, 2.76 and 97.11 ng/g, and 0.1 and 124.9 ng/g, respectively, in the urban areas of Beijing, whereas for the background samples collected from the suburbs of Beijing, the concentrations of Pt, Pd, and Rh were very low and ranged from 0.1 to 0.9 ng/g, 0.5 to 1.4 ng/g, and 0.8 to 2.2 ng/g, respectively. The distributions of PGEs in road dust were an accurate reflection of the levels of pollution and were found to match with the local traffic conditions. A strong positive correlation was established among all the elements found in road dust. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high concentration of Pt, Rh, and Pd in road dust along the main roads of Beijing.

Application of geostatistical methods to arsenic data from soil samples of the Cova dos Mouros mine (Vila Verde-Portugal)

A total of 286 soil samples were collected in the Cova dos Mouros area. All samples were dry sieved into the <200 mesh size fraction and analysed for Fe, Cu, Zn, Pb, Co, Ni, Bi and Mn by atomic absorption spectrometry (AAS) and for As, Se, Sb and Te by atomic absorption spectrometry-hydrid generation (AAS-HG). Only the results of arsenic are discussed in this paper although the survey was extended to all analysed chemical elements. The purpose of this study was to make a risk probability mapping for arsenic that would allow better knowledge about the vulnerability of the soil to arsenic contamination. To achieve this purpose, the initial variable was transformed into an indicator variable using as thresholds the risk-based standards (intervention values) for soils, as proposed by [Swartjes 1999. Risk based assessment of soil and groundwater quality in the Netherlands: Standards and remediation. J. Geochem. Explor.73 1-10]. To account for spatial structure, sample variograms were computed for the main directions of the sampling grid and a spherical model was fitted to each sample variogram (arsenic variable and indicator variables). The parameters of the spherical model fitted to the arsenic variable were used to predict arsenic concentrations at unsampled locations. A risk probability mapping was also done to assess the vulnerability of the soil towards the mining works. The parameters of the spherical model fitted to each indicator variable were used to estimate probabilities of exceeding the corresponding threshold. The use of indicator kriging as an alternative to ordinary kriging for the soil data of Cova dos Mouros produced unbiased probability maps that allowed assessment of the quality of the soil.

Palladium and platinum concentration in soils from the Napoli metropolitan area, Italy: possible effects of catalytic exhausts

Soils from the Napoli metropolitan area (Italy) were evaluated for Pt and Pd concentrations. One hundred and ninety-five (195) samples were collected from residual soils and non-residual soils from flower-beds in a 120 km 2 area on a 0.5 km grid in the downtown-urbanized area and on 1 km grid in suburban zones. The soils <100 mesh size fraction (150 μm) was analyzed for Pt, Pd and 37 other elements by ICP-ES and ICP-MS after aqua regia digestion. Pt and Pd contents range between <2 and 52 μg/kg and between <10 and 110 μg/kg, respectively. A large number of samples from the metropolitan area were characterized by anomalous values for Pt (>6 μg/kg) and Pd (>17 μg/kg). Non-residual soils from flower-beds are located mainly in the urbanized downtown areas subject to heavy traffic and have higher Pt and Pd contents than residual soils from suburban areas. Geochemical maps show a strong correlation between roads with major traffic flow and high Pt and Pd concentrations. In addition, data from most of the downtown flower-beds fall within the three-way catalytic converters (TWC) field identified by [Ely JC, et al. Environ Sci Technol; 35:3816–3822]. This suggests that emissions of abraded fragments from vehicle exhausts may be the source of the high values and geographic distributions of Pd and especially Pt in urban soils of Napoli. Catalytic converters (Pt/Pd/Rh) have been mandatory for gasoline-powered vehicles in Europe since 1993. Italy permitted the use of non-catalytic motor until January, 2002. This is responsible for the high values for both Pt and Pd in the non-residual soils of the urban areas of Napoli.

Effects of intensive fishing on the structure of zooplankton communities and mercury levels

Following the impoundment of hydroelectric reservoirs, a small fraction of the mercury (Hg) in the flooded soils is transformed and released into the ecosystem. This causes an increase in the mercury level in the food chain, particularly in piscivorous fish, and represents a potential risk for human health. In 1998, Hydro-Québec carried out an intensive fishing campaign to examine the feasibility of using intensive fishing as a mitigation tool. The goal of this particular part of the project was to evaluate the impact of intensive fishing on the zooplanktonic communities’ structure and mercury levels. Specifically, the effects of intensive fishing on: (1) total biomass and zooplankton size structure (>500, 200–500, 100–200 and 53–100 μm); (2) species composition; and (3) total mercury and methylmercury (MeHg) concentrations in zooplankton of different size fractions were studied. Although important decreases were observed in total zooplankton biomass or its size structure, it cannot be related to the intensive fishing. The results, however, show major changes in the dominance of macrozooplanktonic species in fished lakes as opposed to reference lakes. Similarly, in contrast to the reference lakes, mercury and MeHg concentrations in the four size fractions of the zooplanktonic communities changed from 1998 to 2000 in the fished lakes. The MeHg concentration increased from approximately 20 to 200 ng/g dw from the 53 to 500 μm mesh size fraction, showing a biomagnification in the food chain. The canonical correspondence analysis showed that lakes dominated by Holopedium gibberum presented higher concentrations of Hg and MeHg than lakes dominated by Daphnia spp.

Structure of laser cladded tungsten carbide composite coatings

Carbide-metal matrix composite materials are used in applications were high wear resistance is critical. The laser surface cladding technique offers new advantages in depositing composite materials wear resistant coatings. Layers of WC in Co and Ni-based alloys matrix composites have been laser cladded on a low carbon steel substrate. Due to the right selection of the laser processing parameters during laser surface cladding porosity and crack free WC-metal composite coatings have been produced. The results of optical and SEM microstructure observations, X-ray phase, and EDS chemical composition analysis as well as cross-sectional microhardness distribution have been presented. The longer the laser beam–composite material interaction time, the higher level of the dissolution of primary carbide phase in metal matrix is to be expected. The primary WC particles dissolution degree depends also on their mesh size and volume fraction in composite material. The processing conditions should be optimized to keep the primary carbides dissolution at minimum.

Review A P/M approach for the fabrication of an orthorhombic titanium aluminide for MMC applications

A study has been undertaken to examine the feasibility of using a powder metallurgy (P/M) approach for the fabrication of an orthorhombic (O; Ti2AlNb)-based titanium aluminide alloy intended for use as a matrix in a continuous fiber reinforced titanium matrix composite (TMC). Spherical powder of Ti-22Al-26Nb (at%) was produced using inert gas atomization. The atomized powder was sieved to −80 mesh (<177 μm) size fraction and used in the fabrication of unreinforced “neat” panels via the tape casting process. Microstructural and phase chemistry examinations of the as-produced powder, thermally exposed powder and neat matrix were conducted using back-scatter electron scanning electron microscope (BSE SEM) imaging, wavelength dispersive spectroscopy (WDS), and TEM analysis. Mechanical behavior studies of the as-fabricated and heat treated neat material included: tensile, creep and isothermal fatigue. Results obtained for the P/M-based neat material were compared to previously obtained foil-based neat data, and to those property requirements necessary to be considered for use as a matrix in the fabrication of O TMCs.

Low Temperature Experimental Investigation of the Effect of High pH Koh Solutions on the Opalinus Shale, Switzerland

AbstractBatch reactor experiments were performed at 150°C, 175°C, and 200°C to determine the effect of high pH KOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25°C, solution composition, and mineralogy were monitored as a function of time for up to ≈ 50 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5–5.0 grams of the 80–200 mesh size fraction of Opalinus shale, and 25 ml of solution (0.08 and 0.008 m KOH). Under these high pH conditions, the general sequence of reaction products observed is the formation of phillipsite, followed by K-feldspar ± K-rectorite. Phillipsite is a metastable intermediate that eventually transforms to K-feldspar. This sequence of mineral reaction products is very different from that found in the NaOH system.

Low Temperature Experimental Investigation of the Effect of High pH Naoh Solutions on the Opalinus Shale, Switzerland

AbstractBatch reactor experiments were performed at 150°C, 175°C, and 200°C to determine the effect of high pH NaOH solutions on the mineralogy of the Opalinus shale. In these experiments, the change in solution quench pH at 25°C, solution composition, and mineralogy were monitored as a function of time for up to ≈40 days. Runs were performed in 50 ml titanium hydrothermal reactor vessels. Each reactor was charged with 0.5–5.0 g of the 80–200 mesh size fraction of Opalinus shale, and 25 ml of solution (0.1 and 0.01 M NaOH). The general sequence of reaction products observed under these high pH conditions include first the formation of analcime, followed by vermiculite, and finally Na-rectorite formation.

Flotation of dolomitic impurities from Jhamarkotra (India) phosphorites

Flotation separation of dolomite from Jhamarkotra phosphorite ore deposit in India, has been achieved using the two-stage conditioning process. An alternate process using a proprietary reagent scheme has also shown considerable promise in removal of dolomitic impurities. Hallimond cell flotation of the 65 × 100 mesh size fraction using sodium oleate as the collector yielded concentrates containing 35% P 2O 5 and 0.9% MgO with phosphate recoveries in the range of 80–90%. Further bench scale studies on 35 × 65 mesh size fraction of the ore resulted in apatite concentrates analyzing 32–36% P 2O 5 at a recovery of 85%. The above-mentioned processes have also been determined to be equally effective in separating dolomitic impurities from sedimentary Florida phosphate rocks. The mechanism of selectivity for the two-stage conditioning process has been attributed to the higher collector adsorption on calcareous ore during the first stage of conditioning and changes in the chemical nature of the adsorbed species upon reconditioning at a lower pH.