Search Results (6)

The exploration of coastal placer deposits, often enriched in critical raw materials demanded by industry, is significantly challenged by the dynamic marine environment and by the limited research devoted to developing dedicated exploration methodologies. This study presents the first systematic integration of multi-source geospatial data in the Rías Baixas for placer mineral prediction in the initial exploratory stage of these deposits. The primary objective is to investigate the presence of Titanium (ilmenite, and rutile), Zirconium (zircon), and Rare Earth Element (REE)-bearing minerals (monazite, xenotime, allanite, and garnets) in Rías Baixas (NW Spain). The methodology includes a lithological reclassification and the generalization of coastal types. These features are then integrated with watershed, coastline dynamics, and mineral occurrence data. Validation includes existing semi-quantitative and qualitative mineral identification data, and new field observations of heavy mineral accumulations. This integration allowed us to identify nine potential and ten predictive areas with a high probability of hosting coastal placers. The validation process showed a 79% spatial correlation, confirming a significant heavy mineral accumulation in 15 areas. This work underscores the efficacy of integrated cartography in prioritizing potential and predictive areas during the crucial first stage of mineral exploration. The methodology can be further enhanced by incorporating additional data, such as stream sediment geochemistry and the application of remote sensing techniques. Full article

The present study aims to investigate the textural, mineralogical and geochemical characteristics of lean grade placer monazite from the Bramhagiri beach sand deposit to assess the possibility for its use in industrial applications. The bulk back dune sand deposit with 18 samples showed the elements uranium and thorium in traces, phosphorus and calcium in minor amounts, and alumina, silica and titanium in major amounts. Since apatite was absent in this placer deposit, P and Ca were attributed to monazite only. Based on the chemical analysis, it was established that the monazite mineral exists in this deposit. The monazite is generally below the −150- to +90-micron size range, and the concentration of the monazite mineral in the bulk back dune sand is around 0.01% by weight. The structural data and complete chemical analysis established that the monazite is Ce-monazite. The monazites with other heavy mineral sands of the Bramhagiri beach placer deposits were derived from the Eastern Ghats, which closely resembles the mineralogical composition of khondalite, charnockite, leptynite and pegmatite groups of rocks. The Eastern Ghats’ provenance appears to be the primary source for the heavy mineral assemblages of the Bramhagiri placer deposit. Thus, these monazite sands are derived from the granulite facies of metamorphic rocks such as khondalites and charnockites from the Eastern Ghats group of rocks. Garnet is the major mineral, following ilmenite and sillimanite. Zircon, rutile and monazite are minor minerals in the deposit. All these minerals are well liberated and have uniform shapes with variable densities and size ranges, with different magnetic, electrical and surface properties. Hence, the occurrences of these heavy minerals are of economic importance. Further, these minerals can be recovered individually for industrial applications. Full article

The effect of borax on the reduction characteristics of Indonesia beach placers was investigated. The effect of grinding alkalinity on the magnetic separation of the reduced sample was also studied in this paper. The mineral phase transformation, microstructures of reduction, and magnetic separation products were analyzed to reveal the enhanced separation mechanism of titanium and iron in beach placer. The borax could effectively improve the metallization rate and the growth of iron grains in a reduced sample. When 3% borax was added to the reduction process, the metallization rate of the reduced beach placer reached 95.64%, and the metal iron grains grew to about 50 μm. Adjusting the grinding alkalinity could prevent the metallic iron from being oxidized and promote the monomer dissociation between mineral particles. The iron powder concentrates with 94.07% total Fe and vanadium-rich titanium slag with 36.32% Ti were obtained by grinding magnetic separation as the grinding alkalinity pH was 13. Full article

A light REE (LREE)-bearing mineral called chevkinite (Ce, La, Ca, Th)₄(Fe²⁺, Mg)₂(Ti, Fe³⁺)₃Si₄O_22, originating from a heavy metal placer deposit Aksu Diamas in Turkey, previously assessed for potential REE extraction as a by-product of magnetite production, was studied using scanning electron microscopy with energy and wavelength-dispersive spectrometers (SEM EDS-WDS). This mineral exhibits analytical challenges associated with severe X-ray energy overlaps between the REE, titanium, and barium. Here, we present an iterative process, showing that SEM EDS-WDS is a viable technique for obtaining good quality quantitative data. SEM EDS-WDS is an in situ, non-destructive, and relatively non-expensive technique, but operator’s experience is essential to obtain good quality data. In cases where the peak fitting remains challenging, in particular, and where the constituents have large differences in abundance, an assessment of the X-ray spectrum to qualitatively assign all peaks is essential prior to quantitative analysis. Full article

In this study, the ilmenite content in beach placer sand was estimated using seven soft computing techniques, namely random forest (RF), artificial neural network (ANN), k-nearest neighbors (kNN), cubist, support vector machine (SVM), stochastic gradient boosting (SGB), and classification and regression tree (CART). The 405 beach placer borehole samples were collected from Southern Suoi Nhum deposit, Binh Thuan province, Vietnam, to test the feasibility of these soft computing techniques in estimating ilmenite content. Heavy mineral analysis indicated that valuable minerals in the placer sand are zircon, ilmenite, leucoxene, rutile, anatase, and monazite. In this study, five materials, namely rutile, anatase, leucoxene, zircon, and monazite, were used as the input variables to estimate ilmenite content based on the above mentioned soft computing models. Of the whole dataset, 325 samples were used to build the regarded soft computing models; 80 remaining samples were used for the models’ verification. Root-mean-squared error (RMSE), determination coefficient (R²), a simple ranking method, and residuals analysis technique were used as the statistical criteria for assessing the model performances. The numerical experiments revealed that soft computing techniques are capable of estimating the content of ilmenite with high accuracy. The residuals analysis also indicated that the SGB model was the most suitable for determining the ilmenite content in the context of this research. Full article

In Brazil, heavy mineral sand deposits are still barely exploited, despite some references to Brazilian reserves and ilmenite concentrate production. The goal of this project is to characterize and investigate the potential recovery of heavy minerals from selected Brazilian placer occurrences. Two areas of the coastal region were chosen, in Piaui state and in Bahia Provinces. In all samples, the heavy minerals of interest (ilmenite, monazite, rutile, and zircon) were identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques and also quantified by X-ray fluorescence spectrometry (XRF) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The total heavy minerals (THM) in the Piaui samples were 6.45% and 10.14% THM, while the figure for the Bahia sample was 3.4% THM. The recovery test of the Bahia sample, using only physical separation equipment such as a shaking table and magnetic separator, showed valuable metallurgical recoveries at around or greater than 70% for each stage, and the final concentrate of pure ilmenite was composed of up to 60.0% titanium dioxide after the differential magnetic separation. Another aim is to compile accessible information about Brazilian heavy mineral main deposits complemented with a short economic overview. Full article