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Differences in the fabric of reconstituted triaxial samples may increase the difficulty of achieving a unique critical state for some soils. Moreover, changes in the salt concentration of bauxite residue can result in non-unique critical state lines (CSLs). To evaluate the effects of fabric and pore-water chemistry on the critical state of bauxite residue, this paper compares the triaxial compression behavior of intact, slurry consolidated, and various forms of moist tamped samples, at a range of salt concentrations. The variations in fabric were also investigated using scanning electron microscopy and nuclear magnetic resonance (NMR) tests. The changes in pore-water chemistry were analyzed using X-ray methods and changes in salt concentration. The results showed that the particle agglomeration induced during reconstitution resulted in a more significant shift of the CSL than the decrease in salt concentration. Microimaging and shear behavior of samples showed that the slurry consolidation method may be the most suitable method for representing in situ behavior of clayey bauxite residue. NMR findings suggest that variations in water retained in the micropores of reconstituted samples stem from differences in microstructure. The implications of changes in salt concentration and sample microstructure on the design of clayey bauxite tailings storage facilities are discussed. [ABSTRACT FROM AUTHOR]

The raw material for smelting brown corundum is high-quality bauxite. As the quality of bauxite decreases, the main impurity, silicon content, increases, which affects the product quality and smelting energy consumption. Additionally, the smelting process produces a significant amount of brown corundum fly dust (BCFD) with a low utilization rate, resulting in resource wastage. In order to utilize low-quality bauxite and BCFD, this article proposes the method of "roasting-alkali leaching." Through mixed desilication, the impact of alkali leaching factors on desilication is investigated, analyzed the desiliconization mechanism of BCFD, and established the kinetics of the desilication reaction. Results indicated that the optimal conditions for mixed desilication are BCFD/bauxite mass ratio of 1:6, desilication temperature of 95°C, desilication time of 30 min, alkali concentration of 110 g/L, and liquid-solid ratio of 10:1, achieving a desilication rate of 60.90%. The Al-Si ratio (A/S) of the concentrate increases from 5.33 to 11.72, meeting the requirements for brown corundum smelting raw materials. The desilication reaction follows a solid shrinkage core model, with a kinetic equation of 1−2/3α−(1−α)2/3 = 15.50exp[−29299/(RT)]·t, and an apparent activation energy of 29.30 kJ/mol. The synergistic mechanism involves fine particles of the BCFD adsorbing on the surface after mixing with the bauxite, increasing the mineral surface area and the activity of silicon, thereby accelerating the reaction rate. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the potential of using alkali activation technology to valorize steel slag and bauxite residue for the production of high-performance pavement blocks. By utilizing these industrial by-products, the study seeks to reduce their environmental impact and support the development of sustainable construction materials. Lab-scale testing showed that bauxite pavers showed a decrease in mechanical strength with increasing replacement of ordinary Portland cement. Partial replacement up to 20% still exceeded 30 MPa in compressive strength. Steel slag-based pavers achieved the 30 MPa threshold required for the application with selected mix designs. Pilot-scale production-optimized formulations and standards testing, including freeze–thaw resistance, confirmed the technical viability of these products. Life cycle analysis indicated a 25–27% reduction in CO2 emissions for slag-based tiles compared to traditional concrete tiles. Moreover, using industrial residue reduced mineral resource depletion. This study examined the properties of the resulting alkali-activated binders, their ecological benefits, and their performance compared to conventional materials. Through a comprehensive analysis of these applications, our research promotes the circular economy and the advancement of sustainable construction products. [ABSTRACT FROM AUTHOR]

The use of reduction leaching in the production of alumina from bauxite by the Bayer process in order to decrease the amount of waste (bauxite residue) by adding elemental iron or aluminum, as well as Fe2+ salts and organic compounds in the stage of high-pressure leaching, requires the purchase of relatively expensive reagents in large quantities. The aim of this study was to investigate the possibility of the use of electrolytically reduced bauxite residue (BR) as a substitute for these reagents. Reduced BR was obtained from Al-goethite containing BR using a bulk cathode in alkaline suspension. The degree of deoxidation of Fe3+ compounds was 55% after 2 h of electrolysis with a current yield of more than 73%. The addition of reduced BR according to the shrinking core model leads to a change in the limiting stage of the high-pressure boehmitic bauxite leaching from a surface chemical reaction to internal diffusion. The activation energy decreased from 32.9 to 17.2 kJ/mol by adding reduced red mud. It was also shown that the addition of reduced BR increased the rate of thickening of the slurry after leaching by a factor of 1.5 and decreased the Na2O losses by 15% without the addition of lime. The solid residue was examined by means of X-ray diffraction analysis and scanning electron microscopy to confirm the presence of magnetite and elemental iron. A preliminary techno-economic analysis was carried out to assess the applicability of the proposed process. [ABSTRACT FROM AUTHOR]

Abstract\nHIGHLIGHTSAs the International Maritime Organization (IMO) has pointed out the bauxite dynamic separation phenomenon in sea transportation, which is different from that of liquefaction, another important factor that affects the maritime safety of solid bulk cargoes has come into our view. However, the industry is short of systematic understanding and research on dynamic separation, and many problems remain to be solved. For example, what is the mechanism of dynamic separation? Which method is suitable for revealing dynamic separation process? How to conduct the risk assessment and control study of bauxite dynamic separation for sea transportation, etc.? This paper aims to provide a systematic overview of the pioneering research on bauxite dynamic separation, summarize the essential features of dynamic separation and appropriate research means, review the progress of research on risk management of ore soil fluidization, and conclude the risk control measures and assessment methods, which are applicable to bauxite dynamic separation. In addition, this article finally presents huge challenges and future research directions in dynamic separation research. This article not only explores specific research ideas for subsequent mechanism research, but also provides theoretical guidelines and method instructions to promote risk control in bauxite dynamic separation during actual sea transport.Analyze the mechanism of bauxite dynamic separation in depth.Highlight the major challenges facing the bauxite dynamic separation study.Propose research and evaluation method of bauxite dynamic separation.Propose feasible suggestions for risk control of bauxite dynamic separation. [ABSTRACT FROM AUTHOR]

[Display omitted] • SE France bauxites formed above exhumed Jurassic-Cretaceous carbonates. • Exhumation was related to the Durance extensional tectonic phase. • Bauxites derived from in-situ weathering and were affected by local reworking. • U-Pb zircon data of SE France bauxites differ from coeval deposits in Sardinia. • Distinct sources support the presence of a rift-related basin between the two areas. Karst bauxites mark episodic exhumation of carbonate platforms, thus providing key information for basin analysis and paleoclimate processes at the regional to continental scale. Most karst bauxite deposits of SE France lie between Jurassic platform carbonates in the footwall and Upper Cretaceous marine to continental sediments in the hanging wall. These deposits delineate a stratigraphic gap coeval with the Durance extensional tectonics, which led to the separation of the Vocontian and South Provence Basins, and shaped the junction between the Alpine Tethys and the Pyrenean Rift. Our new mineralogical and geochemical data show that SE France karst bauxites were affected by in-situ weathering and alteration in conjunction to sedimentary reworking. Statistical analysis of geochemical data indicates that bauxite deposits have a similar chemical footprint, likely pointing to a common and long-lasting bauxitization process. New U-Pb zircon data from the Provence deposits confirm that the source material for the SE France bauxites is to be primarily found in the Hercynian basement. The data suggest the presence of an additional exotic zircon source deriving either from Avalonia and/or Baltica. The comparison of the new U-Pb zircon data with those on coeval bauxites evidences a marked difference between the SE France and the Sardinian deposits. This difference indicates diversification in the detritus provenance of the two areas since the Lower Cretaceous, setting the bauxites of SE France and Sardinia in lateral continuity with the bauxites occurring on the two opposite margins of the Pyrenean Rift, and supporting the development of these deposits on the shoulders of the rift-related basin formed at the eastern termination of the Pyrenean Rift. [ABSTRACT FROM AUTHOR]

This article conducts a study related to the Determination of Operational Costs of PT. Antam Tbk. West Kalimantan Bauxite Mining Business Unit: Types of Letter of Credit, Terms of Letter of Credit, and Transaction Efficiency. The research objects were obtained through online literature reviews such as Google Scholar, Semantic Scholar, and other academic online media as research objects. The main objective of this study is to formulate hypotheses regarding the influence of these variables for future research. The research method uses Systematic Literature Review and Library Search with the utilization of Artificial Intelligence (AI) to obtain related research, sourced from open access journals and e-books. The results of this study are: 1) Types of Letter of Credit affect Operational Costs; 2) Terms of Letter of Credit affect Operational Costs; and 3) Transaction Efficiency affects Operational Costs. [ABSTRACT FROM AUTHOR]

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, there has been increasing concern regarding the widespread occurrence of dyes in aquatic environments, due to their harmful effects on both water quality and human health. This investigation uses bauxite residue as a cost-effective sorbent to eradicate the hazardous reactive blue (RB) dye from aqueous solutions. The reusability potential of bauxite residue was also evaluated. The bauxite residue was characterized by X-ray diffraction, Cation Exchange Capacity, Chemical analysis, FTIR, and Analysis of particle size and particle distribution. The RB dye adsorption parameters revealed that the removal efficiency and adsorption capacity of bauxite residue was 100% and 186.01 mg/g, respectively, under the following adsorption conditions: adsorbent dosage of 0.5 mg/L, initial pH of 2, dye concentration of 50 mg/g, and reaction temperature of 25 °C. Furthermore, the adsorption of RB dye on bauxite residue followed the pseudo-second-order kinetic and Freundlich isotherm models. After one adsorption cycle, the adsorption capacity of bauxite residue for reactive RB removal reached 186.01 mg/g. The regeneration study revealed that the bauxite residue remained 99% of its original condition following the water regeneration cycle. [ABSTRACT FROM AUTHOR]

Concrete, a highly energy-intensive material, contributes approximately 10% of global carbion dioxide (CO2) emissions. To address this issue, incorporating industrial residues in concrete production has emerged as a viable solution, reducing natural resource consumption and lowering the CO2 footprint. Using bauxite residues in concrete has proven to be an environmentally friendly and sustainable approach. In this study, cement mass was partially replaced with bauxite residues (at 5%, 10%, 15%, and 20%), with variations in residue diameter (300 μm, 600 μm, and 2 mm) and in liquid form. The concrete's workability, air content, density, mechanical strength, elasticity, Poisson's ratio, and porosity were assessed with each replacement percentage. The study revealed that bauxite residues can effectively replace up to 20% of cement in a concrete mixture. Although their use slightly affects the fresh properties of concrete, it significantly enhances its mechanical properties. With this approach, a sustainable and eco-friendly concrete without compromising its performance can be created. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biological methods are well-documented as efficient and eco-friendly techniques to convert waste into a green sustainable material. This study demonstrates the potential of organic acid–secreting filamentous fungi such as Aspergillus niger in mitigating the alkalinity of bauxite residue (BR). A series of bioneutralization experiments by adding broth containing Aspergillus niger in different percentages (10%, 15%, 20%, and 25%) with inoculation intervals of 1, 2, 3, 4, and 5 days to BR are performed. The efficacy of fungi is monitored by measuring the pH of BR over an incubation period of 50 days. The analyses of the results reveal that broth additions at all percentages of a 1-day inoculation interval, 15%, 20%, and 25% of 2 and 3-day intervals, and 20% and 25% of a 4-day interval successfully reduce the pH of BR to an acceptable value of 8.5, as prescribed by the Indian Road Congress standard. When considering the economy, it is perceived that 20% broth addition with a 4-day inoculation interval is optimal. The underlying mechanism for pH decline is corroborated by the reaction of H+ ions, dissociated from the organic acids secreted by filamentous fungi, with various alkaline substances of BR. The performance of fungi is further assessed by measuring the rate of decline parameter, which is found to be dependent on percent broth addition and inoculation interval. The outcome of this study gives an insight that microbial-driven remediation could become a practical, sustainable, and eco-friendly method for in situ rehabilitation of BR and thereby convert it into green material. [ABSTRACT FROM AUTHOR]

Abstract The breakthrough of bauxite natural gas in the Taiyuan Formation in the Longdong area of the Ordos Basin makes bauxite natural gas gradually become a new exploration direction. However, the complex sedimentary conditions and diverse developmental strata of the Linxing region present difficulties for the exploration of bauxite gas. In this research, samples of bauxite cores from significant drilling sections in the Linxing area were obtained for comprehensive geochemical, mineralogical, and pore structure analysis. This study investigates the impact of sedimentary environments on the physical properties of bauxite reservoirs within the Benxi Formation, focusing on lithofacies categorization, mineral composition, and pore structure. This study established a lithofacies categorization system that iron minerals, aluminum minerals + titanium minerals, clay minerals as three end‐member components. The study identified four lithofacies types: pure bauxite, clayey bauxite, mixed bauxite, and bauxite mudstone. According to geochemical analysis, the bauxite rock in the study area is deposited in a semi‐enclosed bay with terrestrial freshwater input. The physical properties of bauxite reservoir in the study area are relatively poor, among which the physical properties of bauxite reservoir are the best. Authigenic minerals like pyrite are often filled in dissolution pores. The constraint of sedimentary environment on bauxite reservoir is mainly manifested as the influence on the formation of diaspore mineral framework, and its acidity and alkalinity are very important for the formation of diaspore. Hence, diaspore commonly forms in the shallow lake environments characterized by pure bauxite rock, exhibiting favorable reservoir conditions. This research examines the impact of mineral composition on bauxite reservoirs through the lens of lithofacies and sedimentary environments. The variations in bauxite rock reservoirs across distinct sedimentary environments have been elucidated. It provides a new guidance for the exploration of natural gas in Benxi Formation bauxite in Ordos Basin.

Abstract This study evaluates the influence of the CaO/Al2O3 molar ratio of synthetic calcium aluminate hydrates on the properties of alkali-activated materials based on metakaolin. Calcium aluminate hydrates with CaO/Al2O3 molar ratios of 0.4, 0.6, 0.8, 1.0 and 1.2 were synthesised from bauxite and eggshells. Alkali-activated materials were prepared in which metakaolin was replaced by 0 and 10 wt.% calcium hydroxide and calcium aluminate hydrate with different CaO/Al2O3 molar ratios. Rice husk ash with a SiO2/Na2O molar ratio of 1.6 was used for the preparation of the hardener. The 28-day compressive strengths of alkali-activated materials containing 0 and 10 wt.% calcium aluminate hydrate with different CaO/Al2O3 molar ratios of 0, 0.4, 0.6, 0.8, 1.0 and 1.2 are 48.86, 63.59, 47.36, 47.89, 34.66 and 32.76 MPa, respectively. 22.08 MPa for that containing 10% by weight of calcium hydroxide. The apparent densities are 1.87, 1.79, 1.99 and 2.10 g/cm3, respectively. It has been found that the best molar ratio of CaO to Al2O3 in the structure of the 10% by weight of calcium aluminate hydrate used to replace metakaolin, which is required to produce alkali-activated materials with higher mechanical and physical properties, is about 0.4. Highlights Calcium aluminate hydrates (CAHs) with molar ratio CaO/Al2O3 of 0.4, 0.6, 0.8, 1.0 and 1.2 were prepared using calcined bauxite, calcined eggshell and distillated water. Calcium hydroxide (CH) was prepared using calcined eggshell and distillated water. Metakaolin was substituted by 0 and 10 wt.% of CH and the different CAHs. The highest strength was archived at 63.59 MPa for alkali-activated material using CAH with molar ratio CaO/Al2O3 of 0.4 as additive.

The suitability of microsilica as a raw material for the production of ceramic mullite–silicate proppants was assessed. The chemical and mineralogical compositions of the initial materials were studied. The mineral composition of bauxite is mainly represented by gibbsite Al(OH)3 and, to a lesser extent, kaolinite Al4[Si4O10](OH)8, with impurities of hematite and quartz. It is established that, in order to obtain mullite–silicate proppants, compositions containing 10–20% microsilica are optimal. The sintering of these compositions occurs at 1350–1380 °C. A lightweight ceramic proppant was obtained with a bulk density of 1.21–1.41 g/cm3, breaking ratio at 51.7 MPa of 19.1–20.3%, and sphericity and roundness of 0.7–0.9, and the optimal roasting temperature was determined as 1370–1380 °C.

Bauxite mining, a key aluminum production process, can cause environmental degradation, soil erosion, and biodiversity loss. Reclamation measures like reforestation and water management can restore balance. Red mud, a by-product of alumina production, can enhance soil fertility and plant growth in post-bauxite mining reclamation areas. Its alkalinity and mineral composition reduce reliance on synthetic fertilizers, promoting sustainable soil management and addressing environmental challenges. This study aimed to examine the impact of red mud on soil characteristics and the growth of plants in areas during bauxite mining land reclamation. This study was conducted in the post-reclamation area of bauxite mining in West Kalimantan. The experiment involved two treatments: red mud application and a species of revegetation plant. Plant species consist of the plants Embeng, Forest Guana, Johar, and Rambutan. The study used a randomized block design with 24 experimental units. The parameters measured in the study included pH, organic carbon, nitrogen, phosphorus, exchangeable cations, cation exchange capacity, and base saturation, while growth parameters included a high percentage of plant growth and percentages of increased stem diameter. The findings showed that adding red mud to the planting hole increased soil pH and base saturation, improved nutrient availability, and enhanced plant growth in the areas post-mining bauxite at PT Antam, UBPB West Kalimantan. The Embeng Plant is highly regarded as a suitable plant species for re-vegetating areas after bauxite mining.

Abstract In recent years, industrial gas flow has been obtained from the bauxite gas reservoir in the southwestern Ordos Basin, which has made the identification of aluminium-bearing rock reservoirs a popular topic. To accelerate the exploration and development of this type of gas reservoir, major element testing, rock thin section identification and principal component analysis (PCA) were conducted, and a method for rapid and accurate identification of bauxite reservoirs via conventional logging was established. The test results clearly revealed the vertical stratification of major elements and three lithologies in the aluminium (Al)-bearing rock series in the study area. The log response characteristics of effective gas reservoirs were summarized, providing a basis for subsequent research on identifying effective bauxite reservoirs via mathematical dimensionality reduction of logging curves. The porosity comparison of strata with different lithologies suggests that dissolution pores are more developed in Al-rich layers, providing insight for identifying effective reservoirs by Al2O3 content. On the basis of the above findings, a lithological identification chart of Al-bearing rock series was established via principal component analysis (PCA), and an effective bauxite reservoir logging identification model based on Al2O3 content prediction was developed. The results show that using the dimensionality reduction method for principal component analysis of logging curves with overlapping information can avoid model distortion caused by multicollinearity. The research results can be used to identify bauxite reservoirs quickly and accurately without other test data.

This is an article in the field of mining engineering. The development of aluminum industry is subject to decisive factors such as bauxite resources. As a large aluminum industry country in the world, after nearly two decades of rapid development, domestic bauxite resources are becoming increasingly scarce, and the contradiction between ore supply is becoming increasingly prominent. How to ensure the sustainable supply of China's bauxite resource demand and ensure the sustainable and high-quality development of China's aluminum industry is an urgent problem to be solved. The author believes that in the environment of establishing and improving the economic system of green and low-carbon circular development and promoting high-quality development, in addition to continuously increasing the development and utilization of foreign bauxite resources, we can also strengthen the comprehensive utilization of domestic low-grade bauxite resources, restrict the export of primary aluminum products measures such as transnational transfer of aluminum production capacity and promoting small equity and multi-point investment in overseas aluminum industry, and improve the guarantee ability of sustainable supply of bauxite resources in China.

ABSTRACT Bauxite, as the main aluminium‐bearing mineral in China, is a crucial resource for the industrial production of aluminium and aluminium‐related products. In this study, bauxite‐based aluminium composite Li+ adsorbents were prepared using a liquid‐phase alkaline thermal activation—acid in situ method. The effects of various factors on Li+ adsorption from brine were investigated through single‐factor experiments. Multiple techniques, such as scanning electron microscopy (SEM), energy dispersive x‐ray spectroscopy (EDS), x‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET) method, Fourier transform infrared spectroscopy (FT‐IR), and x‐ray photoelectron spectroscopy (XPS), were employed to characterise and analyse the microstructure, pore size distribution, chemical element distribution, and mineral structure of the adsorbents. In addition, the changes in bauxite structure and properties before and after functionalization were investigated. Results indicate that the adsorption capacity of LATA‐AIS‐LDH‐BX adsorbent prepared by the acid in situ method reached 1.15 mg/g at pH = 7; the adsorption capacity of LATA‐Al‐LDH‐BX adsorbent prepared by the aluminium salt conversion method reached 2.16 mg/g. The adsorption behaviour of both adsorbents followed the pseudo‐second‐order kinetic model and the Langmuir model. In the presence of interfering ions (Na+, K+, SO24+, Mg2+), the composite adsorbents showcased strong selective adsorption capacity for Li+. After five cycles of adsorption–desorption, the adsorption rates decreased by 12.19% and 11.48%, respectively, demonstrating good recycling stability. Furthermore, the Li+ adsorption capacities in salt lake brine reached 0.82 mg/g and 1.48 mg/g, indicating promising potential for industrial application. [ABSTRACT FROM AUTHOR]

Investigation on the occurrence state of Fe2O3 in bauxite and its effect on the bauxite‐based homogenized grogs (BHG) is crucial for the utilization of high‐iron bauxite resources. BHG with different Fe2O3 contents incorporated in the form of high‐iron bauxite was prepared by maintaining the Al2O3 content around 82%. The effect of high‐iron bauxite addition (0, 25, 50 75, 100 wt.%) on the phase composition and microstructure evolution was studied using X‐ray diffractometer, scanning electron microscope, and Factsage software. The results show that part of the Fe2O3 in BHG is dissolved into crystalline phases, while the other part is present as a glass phase. The addition of high‐iron bauxite, coupled with a reduction in the SiO2 content, results in a rise in the corundum content within BHG from 55.0% to 93.6% and a decrease in the mullite content from 44.0% to 2.8%. This change results in a decline in the refractoriness under load of T0.6, dropping from 1593.5°C in the sample without high‐iron bauxite to 1430.7°C in the sample with 100% high‐iron bauxite addition. The microstructure of BHG evolves from the interconnected network of corundum and mullite phases to the structure of corundum bonded by the glass phase. [ABSTRACT FROM AUTHOR]

In the Campania region (Southern Italy), in the Matese Mts. (Albian to Turonian/Coniacian) and Caserta district (Albian to Cenomanian), two karst bauxite deposits outcrop, consisting of flat lenses over shallow karst carbonate. Although the mineralogy and geochemistry of Campania bauxite deposits have been widely studied in recent years, new major and trace elements relationships were provided to highlight paleoclimatic and paleoenvironmental conditions that occurred during their formation. The purpose of this research is to provide for the first time information on the paleoclimatic and paleoenvironmental conditions that affected the bauxites of Campania. These deposits formed during different periods since the Matese deposit formed during intense weathering processes with more abundant precipitation while the Caserta district deposit experienced a more long-lasting exposure event. During the formation of the studied bauxites, the drier conditions favored the replacement of kaolinite by boehmite. R-mode factor analysis showed geochemical affinity among Al2O3, TiO2, and Nb. REEs minerals are mainly associated with the bauxite matrix while Zr, Hf, and V were mainly concentrated in detrital minerals during the later stages of bauxitization. Parental affinity indices (Eu/Eu* vs. Sm/Nd; Eu/Eu* vs. TiO2/Al2O3) assessed the origin of the protolith of the Campania bauxites by rejecting the hypothesis of the dissolution of the bedrock carbonate. The results confirmed the eolian transport of parental material with an Upper Continental Crust and an intermediate to mafic magmatic composition. [ABSTRACT FROM AUTHOR]

The global generation of bauxite residue necessitates environmentally responsible disposal strategies. This study investigated the long-term (5-year) behavior of bauxite residue whose pH was lowered to 8.5, called modified bauxite residue (MBR), using lysimeters to test various configurations: raw MBR or used MBR (UMBR) previously applied for acid mine drainage remediation, sand or soil capping, and revegetation. Throughout the experiment and across all configurations, the pH of the leachates stabilized between 7 and 8 and their salinity decreased. Their low sodium absorption ratio (SAR) indicated minimal risk of material clogging and suitability for salt-tolerant plant growth. Leaching of potentially toxic elements, except vanadium, decreased rapidly after the first year to low levels. Leachate concentrations consistently remained below LD50 for Hyalella azteca and were at least an order of magnitude lower by the experiment's end, except for first-year chromium. Sand capping performed poorly, while revegetation and soil capping slightly increased leaching, though these were negligible given the low final leaching levels. Revegetated MBR shows promise as a suitable and sustainable solution for managing bauxite residues, provided the pH is maintained above 6.5. This study highlights the importance of long-term assessments and appropriate management strategies for bauxite residue disposal. [ABSTRACT FROM AUTHOR]

The bauxite occurrences are associated with Triassic quartz meta-limestones and Jura platform type limestones in Kozağaç-Çamlıktepe (Muğla-Milas). The formation of bauxites is related to the acceleration of the decomposition process of waters with different chemical compositions due to regional climatic conditions. Diaspore is a type of bauxite mineral. Zultanite is a color-changing gemstone and is a diaspore. The homogenisation temperature results show that the zultanite homogenisation temperature varies from 191 to 350°C. The salinity of zultanites varies from low to high (2.1 wt % to 7.5 wt % NaCl eq.). Th CO2 values are range from 26 to 35.7°C, and the Tm CO2 values range from –58 to –64°C. These data show that the gas compositions are not pure carbon dioxide. The high CO2 content of fluid inclusions in the studied zultanite indicates that the zultanite formation is at high-temperature medium-pressure conditions due to retrograde metamorphism of carbonate platforms. The low CO2 content demonstrates that the zultanite might have occurred after the weathering wasprocess. [ABSTRACT FROM AUTHOR]

Alumina-silica based refractories have found vast applications in various industries due to their strong resistance to corrosion and price advantages. In this research work high temperature corrosion resistance of aluminosilicate refractories against silicate melt was investigated. Various refractory brick matrices based on bauxite, chamotte and andalusite were prepared. The microstructure and chemical characteristics before and after corrosion cup test, as well as physical and mechanical properties were evaluated. The results indicated that corrosion resistance is increased in the following order of chamotte < bauxite < andalusite. Chemical composition and porosity were considered as determinant factors influencing corrosion process and mechanical properties of the refractory bricks. Low porosity of the andalusite aggregates raised the corrosion resistance by making limitations for melt infiltration into refractory material. Low mullitization of andalusite reduced the density and mechanical strength in comparison with other aluminosilicates. [ABSTRACT FROM AUTHOR]

While geobotanists have long used plant occurrence to locate subsurface resources, none have utilised floristic surveys as evidence in models of mineral potential. Here, we combine plant species distributions with terrain metrics to produce predictive models showing the probability of bauxite presence. We identified nineteen taxa with statistically significant associations with known bauxite deposits and identified eleven terrain metrics from previous studies. We grouped variables into three variable sets (floristic, topographic, and topo-flora) and produced mineral potential models for each using four algorithms or approaches: (a) a generalised linear model (GLM); (b) random forest (RF); (c) maxent (ME); and (d) a heterogenous stacking ensemble (GLM-RF-ME). Overall, the random forest model outperformed all algorithms including the ensemble based on the area under the curve (AUC) metric. The floristic set of variables outperformed the topographic set (AUC: 0.86 v 0.82). However, together they had the greatest predictive capacity (AUC: 0.89). Six taxa, including Banksia grandis, Leucopogon verticillatus, and Persoonia longifolia, were indicators of bauxite presence, while five other taxa, including Xanthorrhoea preissii and Hypocalymma angustifolium, were associated with bauxite absence. Important topographic variables were topographic wetness, landscape position, and valley depth, which characterised bauxite locations as being well drained, in the upper slope positions of subdued hills, and at some distance from valleys. The addition of floristic surveys provides a new line of evidence about the overlying botanical life that tolerates, accumulates, or avoids bauxite or associated minerals. As opposed to drilling, both datasets can be collected and interrogated at low cost and without impact to the surrounding environment. These data are valuable additions to future applications of mineral potential modelling. [ABSTRACT FROM AUTHOR]

Copyright of China Mining Magazine is the property of China Mining Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In West Africa, in southeastern Guinea, in the Simandou Range region underlain by the Archean gneiss-granite basement, a north–south synclinorium structure is extended, that is composed of the Lower Proterozoic series of metamorphic rocks. A thick sequence of the banded iron formation (itabirites) with interlayers of phyllites and mica schists is exposed in cores of the synclines. According to their composition, the itabirites are subdivided into quartz–magnetite and amphibole–quartz–magnetite varieties. High-grade iron ores (60–66% Fe) formed in a pseudomorphic manner after the itabirites in the Cenozoic lateritic weathering crust. At the Northern Simandou, Zogota, and Pic de Fon deposits, the rich ores compose mantle-shaped orebodies up to 150–350 m deep. The orebodies possess the following vertical zonality: primary magnetite itabirites—martitized itabirites—quartz–martite friable ore—martite friable ore and martite–limonite friable ore—goethite–hematite friable to solid ore—deluvial limonite ore (canga and cuirass). All the types of the high-grade ores are dominated by hematite. The rich iron ores were formed from itabirites as a result of the oxidation of magnetite to martite, the almost complete removal of silica, and the subsequent additional supply of iron and its precipitation in the form of hydroxides. During the formation of the iron ores, kaolin clays and bauxites were formed after the phyllite interlayers. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The suitability of microsilica as a raw material for the production of ceramic mullite–silicate proppants was assessed. The chemical and mineralogical compositions of the initial materials were studied. The mineral composition of bauxite is mainly represented by gibbsite Al(OH)3 and, to a lesser extent, kaolinite Al4[Si4O10](OH)8, with impurities of hematite and quartz. It is established that, in order to obtain mullite–silicate proppants, compositions containing 10–20% microsilica are optimal. The sintering of these compositions occurs at 1350–1380 °C. A lightweight ceramic proppant was obtained with a bulk density of 1.21–1.41 g/cm3, breaking ratio at 51.7 MPa of 19.1–20.3%, and sphericity and roundness of 0.7–0.9, and the optimal roasting temperature was determined as 1370–1380 °C. [ABSTRACT FROM AUTHOR]

The breakthrough of bauxite natural gas in the Taiyuan Formation in the Longdong area of the Ordos Basin makes bauxite natural gas gradually become a new exploration direction. However, the complex sedimentary conditions and diverse developmental strata of the Linxing region present difficulties for the exploration of bauxite gas. In this research, samples of bauxite cores from significant drilling sections in the Linxing area were obtained for comprehensive geochemical, mineralogical, and pore structure analysis. This study investigates the impact of sedimentary environments on the physical properties of bauxite reservoirs within the Benxi Formation, focusing on lithofacies categorization, mineral composition, and pore structure. This study established a lithofacies categorization system that iron minerals, aluminum minerals + titanium minerals, clay minerals as three end‐member components. The study identified four lithofacies types: pure bauxite, clayey bauxite, mixed bauxite, and bauxite mudstone. According to geochemical analysis, the bauxite rock in the study area is deposited in a semi‐enclosed bay with terrestrial freshwater input. The physical properties of bauxite reservoir in the study area are relatively poor, among which the physical properties of bauxite reservoir are the best. Authigenic minerals like pyrite are often filled in dissolution pores. The constraint of sedimentary environment on bauxite reservoir is mainly manifested as the influence on the formation of diaspore mineral framework, and its acidity and alkalinity are very important for the formation of diaspore. Hence, diaspore commonly forms in the shallow lake environments characterized by pure bauxite rock, exhibiting favorable reservoir conditions. This research examines the impact of mineral composition on bauxite reservoirs through the lens of lithofacies and sedimentary environments. The variations in bauxite rock reservoirs across distinct sedimentary environments have been elucidated. It provides a new guidance for the exploration of natural gas in Benxi Formation bauxite in Ordos Basin. [ABSTRACT FROM AUTHOR]

Context: Small mammals are undergoing significant declines across the tropical savannas of northern Australia despite a lack of widespread land clearing. The causes of these declines remain unresolved, but a growing body of evidence suggests that the structural simplification of savannas, namely the degradation of under- and overstorey vegetation by frequent fires and high densities of exotic megaherbivores, is likely to be a significant contributing factor. Aim: We sought to investigate how declining mammals use critical denning resources in high-biomass mesic savannas to help explain drivers of mammal decline in more open and less mesic areas and inform management priorities. Methods: We fitted VHF/GPS collars to nine northern quolls (Dasyurus hallucatus), an Endangered scansorial predatory mammal, from a remnant population located on bauxite plateaus on Cape York Peninsula, Australia, to monitor their nocturnal movement patterns and den use over 1 month. Key results: During this period, northern quolls exclusively denned in trees (either standing hollow trees or fallen logs). The most frequently used den trees tended to be larger, with pronounced trunk leans and multiple hollow entrances from 5 to 20 cm in diameter, whereas the most frequently used den logs tended to be longer and had more hollow entrances from 10 to 20 cm in diameter. All home ranges were confined to the high-biomass savanna habitat found on the bauxite plateaus, with males having a mean home range almost double the size of the mean female home range. Conclusions: The reliance of this population of northern quolls on large hollow-bearing trees for shelter may explain the regional contraction of the northern quoll to high-biomass mesic savannas with an abundance of large trees. Implications: These high-biomass savanna habitats, such as the bauxite plateaus found on the Cape York Peninsula, are likely to be critical for the persistence of the northern quoll, and should be appropriately protected, through management of fire and avoidance of clearing and logging. The drivers of declining small-mammal populations in northern Australia are complex, but may include the structural simplification of tropical savannas. We explored denning preferences and nocturnal movement patterns of the Endangered northern quoll, highlighting the species' reliance on large hollow-bearing trees in high-biomass savanna habitats of Cape York Peninsula, Australia, where these habitats have a critical role for the species' survival. We recommend prioritising conservation efforts in these areas, with a focus on effective fire management and avoidance of clearing and logging. Photograph by Gavin Trewella. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nonferrous Metals (Extractive Metallurgy) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Carboniferous Benxi Formation in southern Shanxi of North China has significant bauxite resource potential; however, the source of its metallogenic material and its sedimentary environment remain unclear. The microscopy, X-ray diffraction, X-ray fluorescence spectroscopy, and inductively coupled plasma mass spectrometry methods were applied in this study to examine the mineralogical, petrographic, and geochemical characteristics. Geochemical proxies of La/Y, Sr/Ba, Al2O3/TiO2, Zr/Sc, Th/Sc, La/Sc, and Th/Co were analyzed to investigate the paleo-depositional environment and provenance of the aluminum-bearing strata. The findings indicate that diaspores are the primary ore minerals in bauxite, while kaolinite and rutile are the predominant gangue minerals. Both the bauxite and claystone/aluminous rocks exhibit high enrichment in Li, Bi, and U, with relative enrichment in In, Sb, Th, Nb, and Ta. Li is notably concentrated in the claystone/aluminous rocks, reaching up to 1994.00 μg/g, primarily occurring in cookeite and boehmite, while U is highly concentrated in the bauxite. The aluminum-bearing strata were primarily formed under alkaline-reducing conditions, with changes in acidity and alkalinity of the environment during the sedimentary diagenetic process. Marine transgressions significantly impacted the sedimentary environment of the aluminum-bearing strata, and the paleoclimate was characterized as hot and humid. The principal factors contributing to enrichment of aluminum in the sedimentary basin were the in situ weathering of aluminum-rich source rocks and the transport of clastic materials from high-aluminum source rocks. The source rocks were closely associated with intermediate-acidic magmatic rocks and potentially related to the weathering of Ordovician carbonates. [ABSTRACT FROM AUTHOR]

When processing low-quality gibbsite–kaolinite bauxites, technologies that involve different methods of mechanical and chemical enrichment with the separation of a difficult-to-utilize fine kaolinite fraction for disposal are used. Before production, problems related to waste storage and disposal arise. To solve the problem of utilization, it is necessary to develop an effective technology for the selective processing of the kaolinite fraction. The efficiency of the technology will depend on the quality of pretreatment of raw materials prior to processing for Al2O3 extraction. Preliminary preparation of kaolinite fraction is associated with the maximum removal of excess silica during chemical enrichment by treatment with an alkaline solution. The presence of silica reduces the quality of final alumina products and requires a large consumption of reagents during the desiliconization of aluminate solutions. During the chemical enrichment of kaolinite fraction in alkaline solution, a serious problem of the co-dissolution of Al2O3 with silica arises. The solution to this problem can be the transformation of phase composition with the transformation of kaolin into a chemically resistant compound corundum, which will create conditions for the selective removal of silica. Kazakhstan's alumina refinery, Pavlodar Aluminum Smelter, processes low-quality gibbsite–kaolinite bauxite from the Krasnogorsk deposit. To improve the quality of bauxite, preliminary gravity enrichment is carried out to separate the kaolinite fraction to a quantity greater than 50%. The purpose of this work was to study the possibility of the selective processing of the kaolinite fraction via various techniques, including preliminary thermal transformation, through sintering, chemical enrichment, autoclave leaching in a circulating aluminate solution, and low-temperature desiliconization, to obtain a solution for decomposition. As a result of this study, the possibility of obtaining a corundum phase after sintering at a temperature of 900–1000 °C was established, which made it possible to obtain 58.8% chemical enrichment through the extraction of SiO2 into solution. Further use of the enriched kaolinite fraction in autoclave leaching in a circulating aluminate solution with low-temperature desiliconization made it possible to obtain an aluminate solution with a caustic modulus of 1.65–1.7, which is suitable for decomposition. [ABSTRACT FROM AUTHOR]

Zinc aluminate (ZnAl 2 O 4 , ZA) ceramic plays an important role in the development of industry and technology because of its many excellent characteristics. ZA ceramic was prepared by solid-state reaction sintering at 1550 °C from bauxite and zinc oxide (ZnO). The effects of different mass ratios of bauxite to ZnO and milling time on the densification, linear shrinkage, porosity, strength and microstructure of ZA ceramic were investigated. It is found that as the relative content of bauxite decreases, the strength of ZA ceramic first increases and then decreases. In addition, suitable milling time is beneficial to improve the performance of ZA ceramic, but too long milling time will be detrimental to its performance. As the mixture with 1:1 of mass ratio of bauxite to ZnO is milled for 5 h, the prepared ZA ceramic has the best performance, 4.79 g/cm3 of bulk density, 3.53 % of apparent porosity, 177.38 MPa of flexural strength and 523.62 MPa of compressive strength. [ABSTRACT FROM AUTHOR]

Ferrotitanium slag can be used to replace bauxite to fabricate refractories owing to its high refractoriness (>1790 °C) and Al 2 O 3 content (≥70 wt%). However, impurities in the ferrotitanium slag is harmful to the materials. In this paper, the mechanical properties and molten slag resistance of Al 2 O 3 –SiC–C castables were improved by replacing part of bauxite with large size ferrotitanium slag (8-5 mm). The large size ferrotitanium slag contained a small amount of impurities, which reacted with SiO 2 at high temperature to form CaO–Al 2 O 3 –SiO 2 –TiO 2 liquid layer on the surface of particles. Under the action of the liquid phase, the ferrotitanium slag particles and the matrix were combined more closely. With the decrease of the particle size of ferrotitanium slag, the slag resistance of the castables began to decrease. This was because the specific surface area of the particles with smaller particle size was relatively larger, large contact area with molten slag resulted in worse slag resistance. Meanwhile, decreasing ferrotitanium slag particle size brought the increase of apparent porosity of Al 2 O 3 –SiC–C castables, resulting in weak mechanical properties. [ABSTRACT FROM AUTHOR]

This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability. [ABSTRACT FROM AUTHOR]