Bauxite Clay Research Articles

Adsorption of Bromothymol Blue Dye onto Bauxite Clay

The goal of the current work is to use an inexpensive, non-toxic material with a high water absorption capacity, bauxite clay, to adsorb the bromothymol blue dye from an aqueous solution. In the production of textiles, leather, paint, food, cosmetics, and pharmaceuticals, synthetic organic compounds are used as dyes almost exclusively in modern industrial processes. Because to their harmful side effects, which include their inherent carcinogenicity, toxicity, and mutagenicity as well as the results of their biological transformation, these dyes pose a serious hazard to the environment when they are released. Clay minerals are valuable as depolluting agents due to their swelling potential, colloidal behavior, and adsorption capacity. The adsorption behavior of bromothymol blue dye from an aqueous solution was studied using bauxite clay. Different variables such as contact time, dosage, ionic strength, and temperature were studied to show the effect on bromothymol blue adsorption onto bauxite clay from an aqueous solution using the batch adsorption method. This study showed that the adsorption decreased by increasing the temperature (15–40 C) and increased by increasing the clay weight from 0.2 to 1.6 g. It also showed as the amount of time rose, the adsorption grew until it reached an equilibrium time of 155 minutes. Thermodynamic metrics including change in free energy (∆G), enthalpy (∆H), and entropy (∆S) all were assessed. A positive correlation was found between the absorbance and the range of concentrations of bromothymol blue (4–32 g/mL) with a correlation coefficient of 0.9911. The maximum wavelength was found and set to 432 nm for all measurements

Provenance shifts in bauxitic clay from Zibo, North China Craton, links tectonics and climate to environmental perturbation

Abstract In the eastern North China Craton, the Zibo bauxitic clay deposits are situated between Permian sandstones. These deposits exhibit distinct characteristics in two horizons. The lower horizon consists of disordered kaolinite with anhedral–subhedral, rounded morphologies that indicate a detrital origin. The upper horizon, however, contains ordered kaolinite. Detrital zircon grains in the lower horizon indicate a unimodal age spectrum with a mean age of ca. 290 Ma and εHf(t) values ranging from −20.8 to −6.0. These findings suggest a continental volcanic arc source on the northern margin of the North China Craton. In contrast, detrital zircon grains in the upper section exhibit a multi-modal detrital age spectrum with significant age peaks at 2500 Ma, 1850 Ma, and 310 Ma that originates from the local basement. The zircon dating establishes a maximum depositional age of ca. 280 ± 3 Ma, which indicates denudation of the source area in the northern North China Craton during the Artinskian stage. The relative abundance of detrital kaolinite indicates a warm and humid climate during the late Artinskian (ca. 283 Ma) to Early Kungurian (ca. 280 Ma), while cold and dry conditions prevailed during the mid–late Kungurian (ca. 277 Ma). The northern North China Craton, which supplied source material to the lower section of Zibo bauxitic clay, experienced rapid uplift and exhumation and underwent intense weathering under high humidity and warm temperatures during the late Artinskian to Early Kungurian. However, the source area shifted from the north to a more central region as the climate transitioned to cold and dry conditions in the mid–late Kungurian. Considering that detrital clay formation is indicative of specific climatic conditions, the Permian bauxitic clay deposits in Zibo provide a valuable record of environmental changes during the late Paleozoic ice age (LPIA; ca. 360–260 Ma).

Geochemical features of lithium–rich bauxite from the Benxi Formation in Qinyuan County, Shanxi, China: Insights into their depositional environment and lithium enrichment

Most bauxites in China are the karst type, which usually enriches lithium (Li) resources. Therefore, Li mineralization theory must be further developed to realize the comprehensive utilization of bauxite resources. The Qinyuan Li–rich bauxite is formed in the Benxi Epoch of the Late Carboniferous and its parent rock is the underlying Ordovician limestone. In this study, the methods of stepwise extraction and element geochemical are utilized to discuss the occurrence state and sedimentary environment of Li in Qinyuan bauxite, respectively. Based on the differences in element composition, the Qinyuan Li–rich bauxite sequence can be divided into clay rocks, bauxitic clays, iron–rich clays, and bauxite from the bottom to the top. The Li content of the Qinyuan bauxite samples is highest in clay rocks (averaging 431 µg/g), followed by bauxitic clays (averaging 288 µg/g), bauxite (averaging 252 µg/g), and iron–rich clays (averaging 202 µg/g). The main mineral compositions of these samples are diaspore, calcite, anatase, pyrite, siderite, kaolinite, and illite. Among them, the Li content is positively correlated with clay mineral contents (R2 = 0.71), indicating that clay minerals are the main Li–rich minerals. More specifically, the clay mineral in bauxitic clays, bauxite, and iron–rich clays are kaolinite, and the positive correlation between Li and kaolinite (R2 = 0.46) indicates that kaolinite is the main Li–rich mineral. Nevertheless, the clay minerals in clay rocks are kaolinite and illite, and the correlation between Li and illite (R2 = 0.54) is higher than kaolinite (R2 = 0.10), indicating that Li is preferentially enriched in illite when kaolinite and illite coexist. It was found that the majority (higher than 99 %) of Li is hosted in the vacant sites of Si–O tetrahedral layers and the Al–O dioctahedral layers of illite and kaolinite to compensate the positive charge deficit caused by replacement of Si4+ and Al3+ in the tetrahedral and dioctahedral layers of clay minerals, respectively. Furthermore, the content ratios between typical elements with varied migration–deposition properties can indicate the depositional environment of Li–rich bauxite. Among them, MgO/Al2O3 and Rb/K (range from1.3 × 10-3 to 7.36 × 10-2 and 3 × 10-4 to 3.44 × 10-2 in samples, respectively) can indicate sedimentary environment. Th/U, V/Cr, and V/(V + Ni) (range from 0.45 to 3.73, 0.85 to 3.54, and 0.27 to 0.89 in samples, respectively) can indicate the paleo–redox conditions. Sr/Cu, CIA, and Cvalue (range from3.53 to 48.2, 93.8 to 99.9, and 0.43 to 7.29 in samples, respectively) can indicate paleoclimate. The results show that the Qinyuan bauxite possibly formed in the hot, humid (Sr/Cu > 5, CIA = 85–100, and Cvalue > 0.8), and dysoxic–anoxic (Th/U = 2–7, V/Cr = 2–4.25, and V/(V + Ni) = 0.46–0.84) marine–continental transitional (MgO/Al2O3 = 0.01–0.1 and Rb/K = 4 × 10-3–6 × 10-3) environment.

Distribution and enrichment mechanism of critical metals in the Danping bauxite deposit, northern Guizhou (SW China)

Critical metals are indispensable for the global scientific and economic development, and their shortage has drawn attention to critical metal exploration in bauxite-related rocks. Bauxite deposits, especially karst-type ones, are usually enriched in critical metals like Li and REE (rare-earth elements La-Lu and Y). In this study, we analyzed the bauxite ore-bearing rocks at Danping (Guizhou, SW China) with a combination of XRF, ICP-MS, XRD, and SEM-EDS techniques, with the aims to investigate the distribution characteristics and enrichment mechanisms of the critical metals (e.g., Li, Ga, Zr, Sc, and REE). The bauxite ore layer at Danping is unconformably contacted with the underlying Huanglong Formation (Fm.) limestone or the Hanjiadian Fm. mudstone/shale, and the overlying Qixia Fm. limestone or Liangshan Fm. carbonaceous shale. Lithium is mainly enriched in the top and bottom of the bauxitic clay strata (abbrev. OBC and UBC, respectively). Gallium is enriched in all the bauxite layers, OBC and UBC. Zirconium is moderately enriched in the bauxite layer, whilst Sc is more enriched in the UBC and its nearby wallrocks (e.g., compact bauxite). REE are locally enriched in/around the basement, with the total REE content of the bauxite ore host being 33.3 to 3082 ppm. In situ analysis indicates that the bauxite-bearing rocks contain REE minerals, including bastnasite and xenotime. Moderate to strong lateritization likely plays a vital role in the different enrichments of critical metals, especially in the bauxite and kaolinitic bauxite zone. Physicochemical conditions of the mineralization are very complex. The Li enrichment may have been closely linked to the clay formation and enrichment, especially during the pre-lateritization and late-leaching stages. REE are mainly enriched in the lateritization stage, and then percolated downward via acidic leaching, where differentiation and re-enrichment occur. When REE migrate to an alkaline environment (caused by Huanglong Fm. limestone), bastnaesite precipitated readily, eventually forming REE-rich claystone and concentrated along the alkaline barrier of carbonate rock.

The formation and evolution of Al‐rich protoliths in the southern Ribeira belt, Brazil: Insights from remnants of a Precambrian paleoweathering surface

AbstractBauxitic clays, clayey bauxites and bauxites are residual products formed from the weathering of aluminosilicate‐rich parent rocks under wet and warm conditions. These deposits show a complex interplay between remobilisation of pre‐existing kaolinitic soils and depositional micro‐environments.In the southern Ribeira belt, Brazil, a paleoweathering surface developed on the continental shelf of the Capiru Group passive margin strata and on its basement/source rocks. This weathering cycle gave rise to a paleosol profile on the continental domain and a karstic paleotopography on the emerged carbonate shelf. The surface and karstic nets were later caped and filled with Al‐rich materials, typical of remobilised soils, bauxitic clays, clayey bauxites and pods of karst‐type bauxites.The age of the disconformity is Pre‐Brazilian/Pan‐African, implying a Neoproterozoic age for the weathering surface. In this study, we investigate the relationship among disconformities, paleosols and karst topography to better understand the stratigraphic control, chemical composition and mineralogy of the Al‐rich materials. We interpret this horizon as the remnants of a (meta‐)paleoweathering surface that can serve as a valuable key bed for stratigraphic correlation and paleogeographic reconstructions.We propose that the triggering process for the genesis of the paleosol profiles, bauxitic material and bauxite pods was a coupled mechanism between favourable climate and uplift along the northern margin of the Curitiba–Angola craton, creating a karstic topography that allowed the down‐plain transport of Al‐rich materials. In a later stage, these deposits were metamorphosed, developing a series of Al silicates in unusual paragenesis, typical of Al‐rich protoliths.The presence of these paragenesis, along with the recognition of the disconformity–paleoweathering surface pair, could be a useful tool to understand the paleoenvironmental and paleogeographic evolution of highly deformed terrains.

Kinetic Study for Janus Green Dye Adsorption from Aqueous Solutions Using Iraqi Bauxite Clay and its Composite

Clays are considered important natural materials in the field of water purification, including bauxite clay (BAU) and its prepared and activated composite (BAU/CMC-AC) with carboxymethyl cellulose polymer. The ad-sorbent surfaces are characterized by FTIR and XRD techniques. The adsorp-tion of green janus (JG) from an aqueous solution with bauxite and its compo-site were studied under the influence of different conditions of the weight and size of adsorbed surface particles, contact time and temperature. The results were found to be: contact time (90, 45) min for maximum quantity adsorbed of (JG) dye on bauxite and its composite respectively. The experimental data were tested on pseudo 1st- and 2nd-order kinetic models. It was shown to apply more with the pseudo-2nd order kinetic model for both adsorbents. It also showed that the highest removal percentage were (78%, 88.5 %) for the bauxite surface and its composite (BAU, BAU/CMC-AC) at the preferred temperature

Geochemistry and secular trends in the middle–late Permian karst bauxite deposits, northwestern Iran

This study focuses on the middle–late Permian bauxite deposits found within karstic depressions and sinkholes of carbonates of the Ruteh and Nessen Formations, northwestern Iran. Data concerning five karst bauxite deposits, each related to a different stratigraphic position within the bedrock, were selected to address the chemical distribution and inter-elemental relationships, especially for critical elements, factors that control bauxite formation, and the parental affinity. The analyzed samples, mainly clayey bauxite and bauxitic clay, are characterized by large compositional fluctuations involving both major and trace elements. The major element composition is dominated by SiO2, TiO2, Al2O3, and Fe2O3. Among the critical elements, compositional fluctuations induce the occurrence of outliers for Co, Nb, Ta, LREE, and HREE, similar to other trace elements, such as Ba, Sr, Cr, U, and Zr. Elemental mobility indicates that most of elements are generally depleted. Among the critical elements, Co is enriched only in several samples of the older deposits, and ΣREE are enriched in some samples of the younger deposits. Factor analysis suggests that, due to the observed Al–Ga covariance, fairly acidic conditions were never attained during bauxitization, and that detrital resistant minerals concentrated during a bauxitization stage, promoting Al–Ti accumulation. Furthermore, the U co-variance with low soluble elements (Nb, Ta, and Th) suggests that U was mostly conservative during the formation of deposits. Cobalt co-varies with Cr, and these elements accumulated during later bauxitization stages, when the massive leaching of silica occurred. The CIA, CIW, and PIA paleo-weathering proxies indicate an upward weathering increase, which suggests a trend toward more extreme weathering conditions in a wetter and warmer climate, according to the Permian global warming. This is consistent with an upward increasing Ba/Sr ratio and the inspection of the A–CN–K plot, where the younger deposits fall close to the A–K edge, involving a clayey precursor requires a rainfall increase. Interestingly, the upward trend toward a warmer and wetter climate was also coupled with paleo-redox conditions promoting cerium oxidation, as depicted by the Ce/Ce* values. Finally, the Eu anomaly and the Sm/Nd ratio indicate that the studied bauxite deposits were mainly derived from a mafic protolith that formed in the middle–late Permian, as a consequence of the volcanism that affected the entire Iranian platform. A cluster of karst bauxites, however, has Eu/Eu* values lower than the average-standard deviation range of the mafic rocks, suggesting a possible contribution of a more differentiated and less mafic protolith. Similarly, the U/Th ratio, at large, supports the hypothesis of a mafic protolith for the middle–late Permian bauxite deposits, although some samples show the U/Th values well above the average-standard deviation range of the mafic rocks, likely indicating that processes promoting the accumulation of resistant minerals with high U/Th ratios cannot be excluded. This means that, in this case, the U/Th ratio does not necessarily reflect the protolith of karst bauxites and that, more in general, this proxy needs to be carefully interpreted when used to assess the parental affinity of residual rocks.

Evaluation of Major and Trace Elements of Orin-Ekiti Bauxitic Clay

Evaluation of Major and Trace Elements of Orin-Ekiti Bauxitic Clay

Leaching efficiency of sulfuric acid on selective lithium leachability from bauxitic claystone

The explosive demand for lithium calls for new lithium resources. A lithium-rich bauxitic clay was selected, and its material composition, phase transformation, lithium leaching efficiency using sulfuric acid were investigated after calcination treatment. In this study, XRF, ICP-AES, ICP-MS, XRD and SEM were employed to characterize bauxitic clay and its calcining products and leaching residues. The results show that bauxitic clay mainly consists of diaspore, illite, montmorillonite and anatase with a major chemical composition of Al2O3 (48.01%), SiO2 (33.06%), K2O (3.88%), TiO2 (2.25%), Fe2O3 (1.07%), MgO (0.46%), and lithium 3170 μg/g. The optimum calcination temperatures were 500 and 600 °C, with 72.34% and 73.61% lithium extracted, respectively, using 15% sulfuric acid leaching for 1 h. The optimal leaching conditions for lithium extraction were a leaching reaction time of 60 min and a 20% (wt/v) sulfuric acid concentration. Lithium leaching in this study was considered to occur via ion exchange instead of mineral dissolution. The findings of this study would be useful and interesting for lithium recovery from bauxitic clay.

Kinetic Study of Methyl Green Dye Adsorption from Aqueous Solution by Bauxite Clay at Different Temperatures

Kinetic experiments were performed to induce of the green methyl dye adsorption from aqueous solution on the bauxite clay. This study includes determination of the adsorption capacity of bauxite clay to methyl green dye adsorption and study the effect of some parameters ( temperature , time ) on the kinetic of the adsorption process of the dye were studied. Quantity of dye adsorbed was increased when the temperature increases from 298 to 318K which indicates that methyl green adsorption processes are endothermic nature . In order to describe the kinetic data and the rate adsorption constants of the pseudo-first-order and second-order kinetics were used . The kinetics data were applied well with the second-order kinetic model. From activation energy value (Ea) for methyl green dye are energetically favorable and the dye adsorption includes physical and chemical adsorption types

Petrography and Geochemistry of Orin-Ekiti Basement Rocks, Southwestern Nigeria: Implications on Bauxitization

The petrography and geochemistry of Orin-Ekiti Basement rocks were evaluated to determine their mineralogical and chemical composition, assessed their petrogenesis and susceptibility to the formation of bauxitic clay. Ten representative rock samples were selected for thin section petrography and bulk rock geochemical analysis using Petrographic microscope and XRF, Rh Tube, 3k Watt respectively. Field observations revealed charnockites as the dominant rock in the study area with other lithotypes including granite, granite gneiss and banded gneiss. Optical examinations indicated the dominance of quartz in all the rocks suggesting the rocks are product of acidic magma. The order of oxides concentration (wt%) is SiO2>Al2O3>Fe2O3>CaO>K2O>MgO>Na2O>TiO2>P2O5. Based on silica content only, the rocks in this study are classified as felsic (granite, granite gneiss and banded gneiss) with SiO2>65% and ultramafic (charnockites) with SiO2<45%. Charnockites with low SiO2, high Al2O3 and TiO2 compared to other rocks in the study area is considered more favourable to form bauxite. The rocks in the study area are classified into calcic-alkali and calcic groups with igneous protolith.

Trace and rare earth elements constraints on the sources of the Yunfeng paleo-karstic bauxite deposit in the Xiuwen-Qingzhen area, Guizhou, China

A number of Carboniferous paleo-karstic bauxite deposits occur in the Xiuwen-Qingzhen area, central Guizhou Province, which constitute an important part of the central Guizhou-Southern Chongqing bauxite belt in southwestern China. These deposits consist of lenticular and stratiform orebodies hosted in the Lower Carboniferous Jiujialu Formation, which lies unconformably above carbonate rocks (mainly dolomite) of the Middle and Upper Cambrian Loushanguan Group, Shilengshui Formation and Lower Cambrian Qingxudong Formation. Although it is generally agreed that the bauxite resulted from weathering of Cambrian rocks below the unconformity, it remains unclear whether the carbonates alone can provide sufficient material for the formation of the deposits. In this study, we examined the mineralogy and major, trace and rare earth elements geochemistry of bauxite and bauxitic clays from the Yunfeng deposit in the Xiuwen-Qingzhen area and compared them to previously published data of a paleo-weathering profile consisting of Loushanguan dolomite underlying the sub-Carboniferous unconformity and the “Black Rock Sequence” of the Lower Cambrian Niutitang Formation, in order to evaluate the sources of the bauxite. The bauxite ores are composed of diaspore as the main ore mineral, along with small amounts of pyrite, arsenopyrite, galena, stibnite, xenotime and uranium-bearing minerals, and are characterized by high contents of uranium and phosphorus. Chondrite-normalized REE patterns and various bivariant diagrams commonly used to study the provenance of bauxite including Eu/Eu∗ vs TiO2/Al2O3, Eu/Eu∗ vs Sm/Nd, TiO2 vs Al2O3, TiO2/Th, Th vs Ta, Th vs Nb and Nb vs Ta suggest that the Loushanguan dolomite and the Niutitang “Black Rock Sequence” are both potential source rocks. However, a comparison in U and Th contents between the paleo-weathering profile of the Loushanguan dolomite and the bauxite samples suggests that the dolomite alone cannot provide the materials for the bauxite ores. Instead, the “Black Rock Sequence” may have contributed most of the ore-forming materials, which are mainly transported from source regions where the Niutitang Formation was exposed, weathered and eroded. Therefore, the Yunfeng bauxite deposit is of mixed autochthonous and allochthonous origin.

Interactions between different acids and bauxitic-based ceramic proppants used in gravel-packed and fractured wells

Proppants are widely used in hydraulic fracturing operations. They consist of solid particles with specific strengths and are used to keep the fractures open to enhance well production. They can be natural sand or artificial ceramic materials. Most ceramic proppants are alumina-based, using kaolin and bauxitic clays as the raw materials. The acid resistance of the fracturing proppant is an essential property. Acids are sometimes needed to clean the fracture by removing scale and clays that reduce the fracture conductivity.In this study, several experiments were conducted using a see-through cell, and an aging cell with 10 wt% HCl, mud acids (6.0 wt% HCl, 1.0 wt% HF and 12.0 wt% HCl, 3.0 wt% HF), i.e., (6:1 and 12:3), and formic (HCOOH), trisodium salt of N-(hydroxyethyl)-ethylenediaminetriacetic acid (Na3-HEDTA) and HF mixtures up to 350 °F. The effects of varying acid system, temperature, soaking time, static and dynamic conditions were examined. The supernatant of solubility tests was analyzed with Fluorine Nuclear Magnetic Resonance (19F NMR) to identify the reaction products. Key elements concentrations were measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). A Zeiss Axiophot microscope was used to acquire images for the proppant particles to study particle shape and effect of acid solubility. Proppants were then analyzed by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The proppant was sieved before and after the experiments. The residual solids were dried and analyzed using a scanning electron microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) capabilities. Effects of acid dissolution on mechanical performance of the proppants were also tested using an automated load frame.The results show that bauxite has a minimal solubility of 0.5 wt% in 10.0 wt% HCl. The proppant is readily soluble in different mud acids, 56.0 wt% dissolved in some cases. The amount dissolved increases with temperature, soaking time, acid concentration, and dynamic conditions. The fines generated and the changes in grain size distribution are detrimental to the proppant conductivity. 19F NMR showed aluminum fluoride complexes with different mud acids due to the high Al/F affinity. XRF showed that the solubility of the proppant occurs mainly in mullite and maghemite due to their high reactivity. Crush resistance test shows a direct relationship between solubility and mechanical strength of bauxite. Assessing solubility effects will help to better design acid treatments without jeopardizing the integrity of the proppant.

Adsorption of Congo Red Dye from Aqueous Solution onto Natural and Modified Bauxite Clays

The adsorption behavior of congo red dye from its aqueous solutions was investigated onto natural and modified bauxite clays. Both bauxite and modified bauxite are primarily characterized by using, FTIR, SEM, AFM, and XRD. Several variables are studied as a function of adsorption including contact time, adsorbent weight, pH, ionic strength, particle size and temperature under batch adsorption technique. The absorbance of the solution before and after adsorption was measured spectrophotometrically. The equilibrium data fit with Langmuir model of adsorption and the linear regression coefficient R2 is found to be 0.9832 and 0.9630 for natural and modified bauxite respectively at 37.5°C which elucidate the best fitting isotherm model. The general shape of the adsorption isotherm of congo red on natural and modified bauxite is consistent with (H-type) on the Giles classification. Different thermodynamic parameters such as Gibb's free energy, enthalpy and entropy of the on-going adsorption process have also been evaluated. The thermodynamic analyses of the congo red adsorption on natural and modified bauxite indicate that the systems are endothermic in nature

Mineralogy, geochemistry, and ore formation of Nuwaifa bauxite deposit, western desert of Iraq

Nuwaifa Formation is a part of sequence stratigraphy that belongs to the Jurassic system exposed in the western desert of Iraq. The Jurassic system consists of Ubaid, Hussainiyat, Amij, Muhaiwir, and Najmah formations. Each formation is composed of basal clastic unit overlain by upper carbonate unit. Nuwaifa karst bauxite was developed in fossil karsts within the Ubaid Formation in areas where maximum intersection of fractures and faults exist. This bauxitization process affected the upper surface of the Ubaid limestone formation, which directly underlies the Nuwaifa bauxite Formation. Nuwaifa Formation represents karst-filling deposit that consists of a mixture of allochthonous (sandstone, claystone, and mudstone) and autochthonous lithofacies (bauxite kaolinite, kaolinitic bauxite, iron-rich bauxite, and flint clay). Most bauxite bodies occur within the autochthonous lithofacies and are lenticular in shape with maximum thickness ranges from few meters to 35 m and in some place up to 100 m. Petrographically, the bauxite deposit exhibits collomorphic-fluidal, pisolitic, oolitic, nodular, brecciated, and skeletal textures indicative of authigenic origin. Mineralogy boehmite and gibbsite are the only bauxite minerals; the former is dominant in the upper parts of the bauxite profiles, whereas the latter is dominant throughout the lower and middle part of the bauxite. Kaolinite, hematite, goethite, calcite, and anatase occur to a lesser extent. The study bauxites are mainly composed of Al2O3 (33–69.6 wt.%), SiO2 (8.4–42 wt.%), Fe2O3 (0.5–15.9 wt.%), and TiO2 (0.7–6.1 wt.%) with LOI ranging from 13.5 to 19.1 wt.%. Geochemical investigations indicate that the immobile elements like Al2O3, TiO2, Cr, Zr, and Ni were obviously enriched, while SiO2, Fe2O3, CaO, MgO, Zn, Co, Ba, Mn, Cu, and Sr were depleted during bauxitization process. The results of this study strongly suggest that the bauxite deposits of the Nuwaifa Formation are derived from the kaolinite of the Lower Hussainiyat Formation.

Adsorption of Congo Red Dye from Aqueous Solution onto Natural and Modified Bauxite Clays

The adsorption behavior of congo red dye from its aqueous solutions was investigated onto natural and modified bauxite clays. Both bauxite and modified bauxite are primarily characterized by using, FTIR, SEM, AFM, and XRD. Several variables are studied as a function of adsorption including contact time, adsorbent weight, pH, ionic strength, particle size and temperature under batch adsorption technique. The absorbance of the solution before and after adsorption was measured spectrophotometrically. The equilibrium data fit with Langmuir model of adsorption and the linear regression coefficient R2 is found to be 0.9832 and 0.9630 for natural and modified bauxite respectively at 37.5°C which elucidate the best fitting isotherm model. The general shape of the adsorption isotherm of congo red on natural and modified bauxite is consistent with (H-type) on the Giles classification. Different thermodynamic parameters such as Gibb's free energy, enthalpy and entropy of the on-going adsorption process have also been evaluated. The thermodynamic analyses of the congo red adsorption on natural and modified bauxite indicate that the systems are endothermic in nature

The Effects of Kaolin and Bauxite Clay Mix Ratios on Physical and Thermal Properties of Refractory Bricks

The Effects of Kaolin and Bauxite Clay Mix Ratios on Physical and Thermal Properties of Refractory Bricks

Improvement of Thermal Shock Resistance Performance of High Alumina Ceramic Filter Support

Mullite-corundum multiphase ceramic materials were prepared at 1400°C for 2h with bauxite chamotte and clay clinker as raw material (size&lt;74 μm), molded at pressure of 50 MPa. Effect of raw materials composition on sintering and themal shock resistance of composite were researched by measurements of apparent porosity, bending strength，thermal shock resistance and thermal expansion rates, and analysed by XRD and SEM. The results showed that the best weigh percentage of raw materials with better sintering and themal shock resistance are bauxite chamotte 50 wt%, clay clinker 50wt% for mullite-corundum multiphase ceramic materials. The test results for high temperature gas cleaning dust removal technology development and the application of the composite ceramic material has important application value.

Geochemistry of Major, Trace, and Rare Earth Elements in Biglar Permo-Triassic Bauxite Deposit, Northwest of Abgarm, Ghazvin Province, Iran

Biglar Permo-Triassic bauxite deposit is located in ~15 km northwest of Abgarm, southwest of Ghazvin province, west of central Iran. It consists of 8 stratiform and discontinuous bauxite lenses lying along the contact of Ruteh (Permian) and Elika (Triassic) carbonate formations. Petrographically, the bauxite ores exhibit collomorphic-fluidal, pseudo-breccia, pseudo-porphyritic, panidiomorphic-granular, nodular, and skeletal textures indicative of authigenic origin. Weathering of andesitic parent rocks led to the formation of Ferruginous laterite, bauxitic clay, and siliceous bauxite. Mass change calculations of elements indicate that Si, and Ba were depleted during bauxitization and Al, Ti, Zr, Nb, Hf, Ga, U, Th, V, and Cr were enriched. However, Fe, Y, Rb, Sr, Co, Ni, LREEs, and HREEs experienced leaching-fixation mechanism during the development of the residual system. Based upon obtained data, the available organic matters, pH variations in weathering solutions, adsorption process, functioning of carbonate bedrock as a geochemical barrier, existing in resistant minerals, and fixation in the neomorphic phases have been shown to play significant role in distribution of trace and rare earth elements. Further geochemical considerations indicate that minerals such as monazite, rhabdophane, belovite, churchite, and xenotime are the potential hosts for rare earth elements in Biglar bauxite deposit.

Petrography and Geochemistry of the Jajarm Bauxite ore Deposit, Northeast Iran: Implications for Source Rock Material and Ore Genesis

The Jajarm bauxite deposit, northeast Iran, is the largest such deposit in Iran. The deposit is sandwiched between the Triassic Elika formation and the Jurassic Shemshak formation, housed within karstic features developed within the former unit. The deposit generally shows an internal layering defined by the following four distinct horizons (from bottom to top): (a) a lower argillaceous horizon, approximately 50-80 cm thick, is mainly composed of clay minerals that directly overlies the carbonate footwall (Elika formation); (b) a bauxitic clay layer approximately 2-3 m thick that consists mainly of hematite, kaolinite, anatase, and diaspore; (c) a red bauxite layer (the main high-grade ore), about 5 m thick and composed of diaspore, kaolinite, anatase, and hematite; and (d) an upper kaolinitic layer that is 20-50 cm thick, composed mainly of kaolinite, and overlain by the Shemshak formation. Detailed petrographic studies reveal diagenetic alteration of the bauxitic protolith. The main observed bauxite textures are microgranular, oolitic, pisolitic, fluidal-collomorphic, and microclastic. Microgranular and microclastic textures associated with the residual fractured and corroded quartz grains, as well as feldspar grains are almost completely replaced by platy diaspore. Geochemical analyses of the red bauxite reveal enrichment of less mobile elements (Nb, Th, Zr, Mo, Ga, and Cr) and depletion of mobile elements (Rb, K, Na, Sr, La, Mg, and Pb); the opposite result is obtained for the bauxitic clay. Chondrite-normalized REE (Rare Earth Element) patterns for the upper kaolinite layer are similar to those for the underlying red bauxite, and the patterns obtained for the lower argillaceous layer are similar to those for the overlying argillaceous bauxite horizon. Ce shows a positive anomaly in the red bauxite and a negative anomaly in the bauxitic clay. The correlation coefficients calculated between REE and other elements demonstrate that the likely REE-bearing minerals are oxides of Ti and Nb, clay minerals, and zircon. In contrast to the present diasporic mineralogical composition of the Jajarm bauxite, the geochemical and mineralogical data indicate an original gibbsitic composition. Finally, the observed mineralogical and textural evidence, combined with the evidence provided by variation diagrams and REE patterns, indicates a mixed origin for the Jajarm bauxite from both basic igneous and sedimentary rocks. In fact, bauxitization was initiated on basic source rocks and continued during reworking and replacement within the karstic features.