Valuable Heavy Minerals Research Articles

Axial or turn-by-turn particle recovery in a spiral concentrator

ABSTRACT Spiral concentrators (“spirals”) are commonly used to separate valuable heavy minerals from light gangue minerals by gravity. This paper examines the classification of particles as they flow down a spiral concentrator and relates the results to the number of turns. The tests show the possibility of reproducing the performance of industrial spirals with a spiral operating in a closed circuit in a laboratory. Results show that knowing the mineral size distributions in the spiral feed is necessary to forecast spiral performance. Further, in the case of iron ore processing, the separation process is practically complete after four turns, with wash water affecting the process rate of recovery. This observation is readily explained by considering the mineral size distribution.

Radiation exposure and health concerns associated with the environmental geochemistry of relatively higher radioactivity in a fresh water basin

This study was carried out on a negligible anthropogenically impacted Indo-Bangla transboundary river basin (Atrai, Bangladesh) to elicit radionuclides' and elemental distributions. Thirty sediment samples were collected from the Bangladesh portion of the river, and instrumental neutron activation analysis and HPGe γ-Spectrometry techniques were used to determine environmental radionuclides (e.g., 232Th, 226Ra, 40K) and associated elemental concentrations, respectively. Metal concentrations (Sc, V, Fe, Eu, Sm, La, Yb, Ce, Lu, Ta, Hf) were determined to comprehend the genesis of greater radioactivity. Recognizing the mean concentration of absorbed gamma dose rate (158.7 hGyh−1) is 2.88-times more than the recommended value (55 hGyh−1) that describes ionizing radiation concerns regarding potential health risks to the surrounding communities and the houses of native residents, which are constructed by Atrai river sediment. This work will assist relevant policymakers in exploring valuable heavy minerals and provide information regarding radiological health risks from a fluvial system.

Recovery of valuable heavy minerals via gravity and magnetic separation operations from Diit Quaternary stream sediments, southern coast of the Red Sea, Egypt

This research aims to concentrate and recover valuable heavy minerals (VHMs) contained in Diit area, southern coast of the Red Sea, Egypt. In this study, three technological samples were collected representing Lens, Delta and Wadi Diit; mineralogical investigation followed by mineral processing was performed in order to recover VHM content. VHMs such as zircon, ilmenite, rutile, sphene, apatite, garnet, and magnetite have been recorded in associations with lesser amounts of uranothorite, monazite, xenotime, fergusonite, khatyrkite, and gold. Initially, two stage wet gravity concentration processes, rougher and scavenger, were carried out via a shaking table to produce a clean concentrate of VHMs, which was used as feed material for the magnetic separation process. Magnetic separation was performed in order to separate ferromagnetic minerals from paramagnetic minerals as well as diamagnetic minerals to obtain clean concentration of these fractions. Assay and Material balance of the concentration steps proved that the THM content of Diit lens increased to 89.70% with a recovery of 91.68% in a weight of 61.08% out of the original sample. While the percentage of THM content in Wadi and Delta Diit samples increased to 48.68 and 47.67% respectively, with recovery equivalent to 71.67 and 82.06% respectively in a weight of 16.51, 18.7% respectively out of the original sample. Finally, a process flowsheet was created according to the optimum conditions for concentration and separation processes.

The Possibility of Separation of Heavy Minerals as Byproduct of the Danube River Gravel Sand Extraction

The history of exploitation of gold from the Danube River’s sandy gravels is centuries long. The extraction of valuable heavy minerals (VHM) concentrate was never intended. Our aim is to find out an effective separation process to produce monomineral concentrates of the following minerals: garnet, ilmenite, zircon, monazite, magnetite, rutile, gold. The essential condition is to use no chemistry (no flotation, leaching, activating). The experimental concentrates were prepared by sluicing on active river channel. Next, the separation results were achieved using gravity and electromagnetic methods with different magnetic intensities. The prepared rutile contained from 63.3% TiO2 to 87% TiO2. The ilmenite concentrate contained 20.5% TiO2 and 39.2% ilmenite. The garnet concentrate contained 94% garnet. The monazite concentrate contained 86.6% monazite, and the sum of REE oxides was 50.1%. The zircon concentrate containing 63.7% ZrO2 means that the prepared concentrate contained 96.1% zircon.

Textural characteristics of surficial sediments along the Noakhali coast, Bangladesh: An implication for mineral placer deposits exploration

This study aimed to explore mineral placer deposits analyzing textural characteristics; mean size (Mz), standard deviation (σi), skewness (Ski), kurtosis (KG), and the depositional environments of surficial sediments deposited in the Noakhali coast along the Meghna River estuary. A total of nine sediment samples were collected, and the textural parameters were analyzed by a laser particle size analyzer (Microtrac S3500). The mean size of the sediment samples ranged from 3.063 Φ to 5.11 Φ, where the seven samples exhibited sandy-silt texture and only two samples silty-sand texture. However, all the samples presented unimodal grain size distribution. A minimal amount of clay (0.12–1.4%) had been found in three samples collected from Urir Char Island. Higher values of standard deviation (4.15 Φ to 5.76 Φ) indicated extremely poorly sorted sediments. Skewness value varied from 0.107 to 0.510 expressed fine to very fine skewness, and kurtosis value from 0.1033 to 1.525 exhibited a mesokurtic to very leptokurtic nature of the sediments. These textural characteristics indicated a low to moderate energy deposition of finer (mostly silt), unidirectional, and riverine sediments. Linear discriminant analysis (LDA) results revealed the littoral, shallow marine, and fluvial deposition of the sediments. CM pattern showed the deposition of sediments by graded suspension without rolling and uniform suspension. Both of these processes indicated low to moderate energy deposition of sediments. As the majority of samples were silt dominated, there are very low prospects of finding valuable heavy minerals except two locations (SP-04, 06) where sand is dominated, and minerals placers could be found there. Low to moderate depositional environments also indicated fewer prospects of finding mineral placer deposits in the studied area.

Distribution and characterization of heavy minerals in Meghna River sand deposits, Bangladesh

Heavy mineral (HM) concentrations in sand bar deposits of the Meghna River were evaluated using optical microscopy, X-Ray Diffraction (XRD), X-Ray Fluorescence spectrometry (XRF), Scanning Electron Microscopy (SEM) and Electron Probe Microanalysis (EPMA) to determine the mineralogy, geochemistry and likely source rocks of the sands, and to examine the distribution and HM potential of the valuable heavy minerals, ilmenite and garnet. The Meghna sands were dominated by the light minerals quartz and feldspar and grainsize analysis results showed that>78 wt.% of the sand population fell within the size range of fine to very fine sand (−250 + 63 μm). The HM component made up around 9 wt.% and consisted mainly of amphibole (∼17–46 wt.%), epidote (∼7–30 wt.%) and garnet (∼3–21 wt.%). Fe-Ti oxide minerals including ilmenite, rutile, and titanomagnetite were present at levels of 0.7–7 wt.% with the magnetite content at 0.9–7 wt.%. The textures (moderate sorting, sub angular) and significant feldspar (6–15 wt.%) content in the sands indicated low degrees of hydraulic sorting and low amounts of alteration/weathering. The HM assemblage indicated a likely mixed source area of varying metamorphic grade (low to high) facies and igneous rocks. EPMA results from the detrital ilmenites and garnets showed that for ilmenite, TiO2 contents were between 42.9 and 54.5 wt.% (ave. 51 wt.%), with overall low impurities, while the garnet compositions were dominated by Fe-rich, almandine types. From the chemical analysis of individual garnet and ilmenite grains, it is likely the Meghna River sands have good potential for commercial extraction of garnet and ilmenite.

Determination of Minerals of Cassiterite Tailings and its Recycling Potential Using Empirical Method at Plateau State Nigeria

The mineral potential of cassiterite fines from tailing dumps in the Jos Tin Mining Community Resource Centre (MCRC), Plateau State Nigeria, were studied through a wet concentration process and dry electrostatic and magnetic processes and then evaluated using empirical evidence. Three samples of the tailing dumps with the size of mineral smaller than 5 mm were collected at random through the “Tin Mining Community Resource Centre”. The huge pile of the tailing dumps may have an environmental impact in the area, so they need to be treated and recovered for the valuable heavy minerals and sand tailing for the local construction industry. The grade of the average tailing dumps as analyzed using XRF were 2.08% Sn, 3.51% Nb, 25.5% Fe, 14.91%Ti, 8.36% Zr, 12.99% Al, and 45.68% Si. The percentage compositions of the cassiterite tailings were expressed to its simplest genetic mineral forms using an empirical formula. The genetic mineral forms were ilmenite, zircon and sand. Since ilmenite has the highest concentration in the cassiterite tailings and the highest economic values, then recycling of ilmenite should be ascertained. After the wet processing by the screen, hydro cyclone, spiral concentrator, and shaking table, the concentrate consists the most of, ilmenite, zircon, and sand. The following dry processes used rotary dryer, screening, electrostatic separator, magnetic separator to separate cassiterite from the heavy minerals and sand. The final iron and titanium concentrate can be upgraded to 72% Fe and Ti using certain reagents such as fluoride acids which can be sold to the Iron ore smelting plant.

Distribution, Separation and Characterisation of Valuable Heavy Minerals from the Brahmaputra River Basin, Kurigram District, Bangladesh

Bangladesh’s heavy minerals deposits in river systems remain largely unexplored with past research restricted to beach placer deposits along the south-eastern coastline of the country. In this study, 64 samples were collected from stable sand bars from the northern Brahmaputra River. The average total heavy minerals (THM) from all sample sites was 10.73 wt%, with the THM concentrations generally highest at the outermost edges of the river and lowest within the mid-channel regions. There was no variation in THM content from north (upstream) to south (downstream). Valuable heavy minerals (VHMs) magnetite, ilmenite, garnet and zircon made up around 25–30 wt% of the THM content, with other heavy minerals including amphibole, pyroxene, kyanite, sillimanite, monazite, apatite and xenotime making up the remaining 70–75 wt%. A VHM distribution map showed that the upstream division of the studied area appeared to be the most prospective for valuable heavy minerals. A bench scale heavy mineral sands beneficiation flowsheet involving unit processes employing gravity, magnetic and electrostatic properties was designed and based on a detailed characterisation and phase analysis of the resulting fractions, it was determined that VHMs made up ~2 wt% of the material recovered. Of these, garnet and ilmenite made up the bulk of the VHMs at levels of 0.88 and 0.51 wt%, respectively, with recoveries of >83%. Characterisation of the concentrates showed that further refinement of the processing conditions is required to generate concentrates that are potentially suitable for commercial applications.

Concentration and Recovery of Valuable Heavy Minerals from Dredged Fine Aggregate Waste

Inside the finest fractions of aggregates, usually wasted by ready mix concrete companies, valuable heavy minerals content is substantial. The concentration and recovery of valuable heavy minerals contained in dredged fine aggregates waste, located in Pyeongtaek South Korea, were investigated to develop a process that can recover and concentrate most of each heavy mineral. The raw material contains ilmenite, magnetite, monazite, and zircon. A gravity separation, recirculating the middlings recovered ilmenite, magnetite, monazite, and zircon with 44.05%, 36.90%, 53.76%, and 69.7% respectively. Nevertheless, a magnetic separation followed by gravity separation of the non-magnetic fraction further improved the recovery of ilmenite, magnetite, monazite, and zircon to 86.96%, 85.09%, 91.06%, and 90.82% respectively. This concentrate was separated at different magnetic intensities. Magnetite was concentrated at 0.05 T, resulting in a recovery of 23.4% and grade of 95.1 wt%. Ilmenite was at 0.4 T, with a recovery of 55.2% and grade of 84.2 wt%. Monazite was at 0.9 T, with a recovery of 59.3% and rare earth oxide content of 45.2%, the non-magnetic fraction has a high zircon content, the recovery was 70.6% and grade of 91.8 wt%.

Occurrence and distribution of valuable heavy minerals in sand deposits of the Jamuna River, Bangladesh

A mineralogical and chemical investigation of surface and subsurface samples from the upper, middle and lower parts of the Jamuna River was carried out with a view to assessing the distribution and recovery potential of the heavy minerals ilmenite and garnet. The HM component in the Jamuna sands is ~10% consisting predominantly of amphibole, epidote and garnet with significant amounts of opaque minerals (ilmenite, magnetite, titanomagnetite, etc). A greater abundance of garnet was present in the fine to medium sized fractions (125–250 µm) and lower garnet concentrations were observed in the very fine sized fraction (<63 µm). The fine size fractions also have increased amounts of clays and clay-like minerals. Potentially high value HMs such as zircon and rutile were also concentrated in the <63 µm size fractions.The ilmenite grains are characterised by TiO2 content between 34.2 and 52.8 wt-% with low levels of impurities. The garnet geochemistry is more variable but dominated overall by almandine-rich compositions. The characteristic heavy mineral suite of garnet, epidote, amphibole, kyanite, and staurolite, as well as the garnet and ilmenite chemistry reveals the sediments are derived from mixed source areas of varying metamorphic grade (low to high) facies and igneous rocks. Based on these results, the Jamuna River sands have good potential for recovery and exploitation of both garnet and ilmenite.

Possible generation and existence of quartz veins at Cisolok Geothermal Area

Cisolok area located at Southern West Java shows various geothermal manifestations. The igneous and volcanic rocks forming the main component of lithology in the area contains quartz veins. This indicates the rocks units in the area may have a close relation to the widely known Cikotok Fomation containing valuable minerals. Macroscopic description of Cisolok quartz vein samples show pyrite and possibly other heavy metal minerals in the veins. Geological condition shown close relation of Cikotok Formation having older geological age to dasitic volcanic rocks extrusted in Cisolok geothermal area. Further and detail research of quartz veins in Cisolok geothermal area will provide relationship to the Cikotok Formation, possible generation and component of valuable heavy minerals. This paper discusses the case condition under lithological and stratigraphic analysis of the volcanic and igneous rocks having quartz veins at Cisolok geothermal area.

Grade and product quality control by microCT scanning of the world class Namakwa Sands Ti-Zr placer deposit West Coast, South Africa: An orientation study

The Namakwa Sands operation is a world class producer of zircon, rutile and ilmenite from mainly semi-consolidated marine and dune sands. This orientation study shows that the high density contrast between the economic minerals as well as the diverse gangue mineralogy allows the use of microCT scanning as a qualitative and quantitative analytical tool. The method has demonstrated the ability to quantify final product quality, grain size distribution, grain shape definition and the identification of external and internal mineral textures. Grain size distribution data generated by microCT scans compares well with data produced by other analytical methods. As a result, the method has the potential to be applied to in situ resource calculations (total heavy minerals - THM, valuable heavy minerals - VHM), run-of-mine (ROM) grade control and the various stages of the mineral beneficiation process. MicroCT scanning applied to heavy mineral producing operations appears promising and should be further assessed against traditional analytical methods. The method also has the ability to assist sedimentological studies with respect to in situ quantitative grain size and sphericity determinations.

The coastal heavy mineral sand deposits of Africa

The trailing margin of the stable African continent is the depositional environment of several heavy mineral placer deposits of which seven have developed into viable world class operations producing titanium feedstock (ilmenite, rutile, leucoxene) and zircon. At least 30 other deposits are marginal under the present global economic climate but have the potential to be turned into account in the medium term with an increase in demand and higher commodity prices. Combined, the seven operating mines are the biggest single producer of titanium feedstock in the world and the second largest producer of zircon after Australia. Mineral resources are vast and the extensive African coastline offers significant exploration potential and possibly is the largest depository of valuable heavy minerals (VHM) on the planet. Generally, Pliocene to Holocene unconsolidated, siliciclastic sands of predominantly marine-aeolian, but locally fluvial origin host the heavy mineral suite and deposits are large coast-parallel dune fields with or without minor strandlines. Tonnages of these deposits are large and in several instances exceed a billion tons with grades between 2 and 12 percent total heavy minerals (THM). Deposit characteristics are influenced by continental tectonics, coastal morphology, sea level changes, tides, climate and the altered, eroded nature and composition of the provenance. The formation of an economically viable deposit requires the juxtaposition of most, if not all of these conditions to favour heavy mineral concentration with a high VHM content. Mining is by open cast using either dry mechanized, hydraulic monitoring, or floating dredge and wet concentrator methodologies. Mineral separation uses physical properties such as density, magnetic susceptibility and electrical conductivity to produce high quality concentrates for the international market. Only three of the mines, all located in South Africa, have their own smelters that convert ilmenite into titanium slag and pig iron. Coastal environments are all eco-sensitive and mine site rehabilitation is employed throughout, including effective disposal of radiogenic tailings associated with high U+Th zircon and monazite. The most effective exploration methods for these deposits include identification of trailing continental margins with Neogene to Quaternary coastal strandlines and dune fields spatially related to geomorphological features such as headlands and significant fluvial systems. High-resolution ground and aeromagnetic surveys reflecting ilmenite and traces of magnetite, coupled with radiometric surveys related to monazite and high U+Th zircon content have been the most effective geophysical methods for these deposits. Reconnaissance followed by detailed infill drilling of anomalous areas by truck mounted rotary drill to collect samples for THM and VHM determinations is the industry standard.

Recovery of Fine Cassiterite from Tailing Dump in Jarin Tin Mine, Thailand

The beneficiation of cassiterite fines from tailing dumps in the Jarin Tin Mine, Thailand were studied through a wet concentration process and dry electrostatic and magnetic processes. The tailing dumps with the size of mineral smaller than 5 mm was collected through the tin mining in the area 20 years ago with the total amount of 17 million tons. The huge pile of the tailing dump may impact environmental in the area, so they need to be treated and recovered for the valuable heavy minerals and sand tailing for the local construction industry. The grade of the tailing dumps are 0.05% Sn, 0.002% Nb, 0.001% Ta. After the wet processing by the screen, hydrocyclone, spiral concentrator, and shaking table, the concentrate consist the most of cassiterite, ilmenite, garnet, zircon, monazite, xenotime, and quartz, containing 20% Sn with a yield of approximately 0.2%. The following dry processes used rotary dryer, screening, electrostatic separator, magnetic separator to separate cassiterite from the heavy minerals and quartz. The final tin concentrate can be upgraded to 72% Sn which can be sold to the tin smelting plant. The economic analysis of the cassiterite recovery processes was conducted using the discounted cash flow model in order to address the cost and benefit of the processes.

Valuable heavy minerals from the Brahmaputra River sands of Northern Bangladesh

The sands of Bangladesh's rivers are potentially economically important hosts for heavy mineral (HM) resources. Characterisation tests carried out by the authors on 50 sand samples collected from sand bars of the Brahmaputra River in northern Bangladesh revealed that the HM assemblage of the predominantly quartz-rich sands ranged from 4.5 to 17.0% (by weight) HM. The HM assemblage of the samples tested predominantly comprised amphibole, epidote, garnet, kyanite and feldspars along with minor amounts of the valuable heavy mineral (VHM) components of ilmenite, magnetite, rutile and zircon. The HMs were generally well liberated and had an angular to sub-round texture. A grain size analysis of a composite sample prepared from a subset of 7 of the 50 samples collected indicated that >75% of the total HM assemblage was within the +250 to −125 µm size fraction with VHMs enriched in the size fractions −250 to +125 µm and −125 to +63 µm. The total HM contents in the coarser −500 to +250 µm size fraction and the finer −63 µm size fractions were negligible. The potentially recoverable VHM components of the composite included magnetite (∼3%), ilmenite (∼4%), titanite (∼1%), titanomagnetite (∼1%), zircon (∼0.5%) and rutile (∼0.4%). Preliminary laboratory separation studies on a bulk sample indicated that magnetite-, ilmenite-, rutile- and zircon-rich concentrates could be prepared from the sands. Analyses of the ilmenite indicated that the ilmenite was primary in composition (∼34% Ti), low in detrimental impurities and would be suitable for pigment production via the sulphate processing route. The zircon and rutile components were also low in total impurities and as such, little or no further processing would be required to produce saleable concentrates of these VHMs. However, the magnetite concentrate was contaminated by composite magnetite/silicate particles and further work involving fine grinding would be required to liberate the magnetite particles and generate a magnetite-rich product.

Composition of ilmenite and provenance of zircon in northern Brazil

The mineral ilmenite (FeTiO3) is an important component of heavy-mineral placer deposits and constitutes the largest volume of valuable mineral in such deposits. The minerals zircon (ZrSiO4) and rutile (TiO2), which occur in lower concentrations than ilmenite in the deposits, have a greater value per ton – c. 1100 and 900 $/ton respectively – compared to ilmenite that ranges from 100 to 200 $/ton depending on its composition. Other minerals such as staurolite, sillimanite, amphibole and garnet are generally also present in placer deposits, but are of minor or no commercial value and, e.g. amphibole needs to be separated from the valuable heavy minerals which adds to the production cost.

Production of heavy minerals concentrate and bitumen from oil sands froth treatment tailings

AbstractIn producing valuable heavy minerals, including zircon and those bearing titanium dioxide, into a heavy minerals concentrate (HMC), the key technical challenges involve bitumen removal from mineral particle surfaces, rejection of fine gangue and recovery of residual solvent. (Organics and fines contamination severely sours downstream heavy minerals production performance). This is accomplished in a manner that is both conducive and integral with oil sands current bitumen production and processing operations. The Company's research and development efforts are based on sophisticated variations of common unit operations, including flotation, solvent extraction and vapour‐phase stripping. Experimentation has indicated optimal design parameters for these unit operations. A large‐scale physical demonstration was completed with performance that has met or exceeded expectations and, after several months of operation, commercial benefits arising from these novel processes have largely been confirmed and validated. Clean HMC with attractive mineralogy is produced containing residual bitumen values sufficiently low to affect high downstream recoveries of zircon (and titania), while producing coker‐feed quality bitumen.

Characterization of the sand of Brahmaputra river of Bangladesh

The aim of this paper is to study on the mineralogy, morphology, magnetic property and composition of the sand of Brahmaputra River, Bangladesh. The sand has been collected from randomly selected seven places and separated by High Intensity Rolling Magnetic Separator into three fractions, viz. magnetic, para-magnetic and non-magnetic parts. The identifications of the valuable heavy minerals existing in these fractions have been performed. The valuable heavy minerals in the separated fractions have been counted under reflected and polarizing microscope and it is found that the magnetic fraction contains ilmenite, magnetite and garnet. The major grain size fraction of the magnetic fraction is 125 - 250 ?m (57.18%). Zircon, rutile, xenotime, monazite, sillimanite etc. have been counted in other two fractions. X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Isodynamic Separator have been applied for mineral assessment and to quantify the relative proportion of mineral species. DOI: http://dx.doi.org/10.3329/bjsir.v47i2.11448 Bangladesh J. Sci. Ind. Res. 47(2), 167-172, 2012