The lateritic bauxite deposits discovered in Melugai Village, West Kalimantan, occur within a lateritic belt zone characterized by extensive and high-quality bauxite occurrences. This study aims to examine the geochemical control of parent rocks influencing the ALCC content in lateritic bauxite deposits. The methods employed include geological mapping, petrographic and petrological analyses, X-Ray Diffraction (XRD) and X-ray fluorescence (XRF) testing. Geomorphologically, the study area is divided into two morphological units gently undulating hills and moderately undulating hills. The drainage pattern in the study area is classified as dendritic. Bauxite deposits are classified into two types based on their parent rocks, namely metatuff and meta-andesite. Bauxite derived from metatuff has an average AL-Ch content of 47.53% (range 44.86-50.06%), categorized as medium-grade bauxite with intense lateritization. In contrast, bauxite derived from meta-andesite has an average ALCh content of 32.25% (range 26.27-38.24%), classified as low-grade bauxite with weak to moderate lateritization. These results indicate that bauxite derived from meta-tuff exhibits a superior AL-Ch content compared to bauxite originating from meta-andesite. This finding suggests that meta-tuff-sourced bauxite contains a more abundant presence of gibbsite minerals, which subsequently controls the high AL-Ch concentration within the bauxite ore.

A new certified reference material for NORM in mineral aluminium ore (bauxite) - IAEA-493.

Illite, a prevalent clay mineral found in hydrated bauxite ore, decreases the aluminum-to-silicon ratio (Al < 7) while inducing competitive crystallization between sodium and potassium during the leaching process, thereby reducing the leaching efficiency of aluminum oxide. Consequently, illite-type bauxite ores are typically subjected to desiliconization prior to undergoing Bayer process leaching. However, this conventional desiliconization exhibits limited efficacy in illite removal and requires further refinement. To overcome these limitations, this study proposes the 'calcification-potassium alkali'(CPA) process, which substitutes KOH for NaOH in a simulated Bayer process targeting illite. This strategy alleviates sodium-potassium competition and facilitates the complete utilization of elements to synthesize potassium aluminosilicate. Furthermore, calcium oxide is partially incorporated to purify the mother liquor. Experimental investigations were conducted to evaluate leaching performance under varying conditions, leading to the determination of optimal parameters: a temperature of 280°C, a calcium-silicon ratio of 0.2, a liquid-solid ratio of 5:1, a K2O concentration of 200g/L, and a reaction duration of 60min. Under these conditions, the illite conversion rate reached 98.65%, with the effective K₂O and SiO2 contents in the product measured at 21.73% and 27.17%, corresponding to 89.38% and 86.54% of the total K2O and SiO2, respectively. Moreover, these parameters satisfy the national standards for organic-inorganic compound fertilizers, enabling subsequent production of mineral potassium-silicon fertilizers. Further leaching experiments on illite-type hydrated bauxite demonstrated efficient aluminum extraction, achieving a leaching rate of 73.82%, while effecting a phase transformation of the aluminum-silicon mineral from hydrated sodium aluminum silicate (Na2O·Al2O3·1.7SiO2·nH2O), typical of the traditional Bayer process, to potassium aluminum silicate (K2O·Al2O3·SiO2). This transformation can be utilized to prepare mineral potassium silicate fertilizers, which supply essential nutrients to plants and promote environmentally sustainable practices within both metallurgical and agricultural industries.

ABSTRACT The rise in greenhouse gas emissions, mainly anthropogenic CO 2 , is causing global warming that leads to climate change and has become a matter of global concern. This review investigates the use of red mud in CO 2 capture and highlights recent advancements over the past 25 years. The bauxite ore is digested with sodium hydroxide to form sodium aluminate using Bayer's process, leaving behind a highly alkaline residue known as red mud. This residue is a well‐suited feedstock material for CO 2 capture processes and its subsequent neutralization. This article discusses the fundamentals of red mud and various pathways for carbonation. Then, the chemical and mineralogical components of red mud that contribute to the adsorption of CO 2 are investigated. It then focuses on research progress and provides an up‐to‐date review of recent advances in CO 2 capture using red mud. This article reviews the mechanism and critically evaluates the process variables that influence the adsorption of CO 2 in red mud. It also provides insight into recent activation methods to improve its capacity. It then discusses the associated post‐carbonation challenges with red mud, concluding that further research is needed in reshaping red mud's perception from industrial waste to a valuable feedstock material for key carbon‐emitting industries. This review serves as a comprehensive reference in the emerging area of CO 2 capture using red mud and addresses the distinct gap of process variables, mechanisms, and post‐carbonation challenges. The ultimate aim is to resolve the CO 2 emitted into the atmosphere and its simultaneous neutralization.

Aluminum is one of the most produced metals worldwide. The Bayer process extracts aluminum from bauxite ores and generates bauxite residue as an environmentally hazardous waste with a low recycling rate and increasing accumulation. The high Fe content in the residue makes it cost prohibitive to extract the remaining aluminum. We present here a process using flash Joule heating combined with chlorination (FJH-Cl2) to remove iron and heavy metals from bauxite residues. With one-step FJH-Cl2 treatment in 1 min, >96% of the Fe can be removed as volatile FeCl3 from bauxite residues while retaining ∼ 99% of the Al in the residue. The corundum-rich residue can be sintered into high-performing ceramics, underscoring the valorization of the bauxite residue. Life-cycle assessment and techno-economic analysis show that the FJH-Cl2 process has far lower global warming emissions, energy consumption, and costs when compared to alternative processes. This highlights the potential of FJH-Cl2 as an efficient method for upcycling bauxite residues into valuable Al resources and high-performance materials.

Abstract Recently, a large number of worldwide supergene REE-fluorocarbonate deposits were discovered, one of which occurred in the Um Bogma area in SW Sinai, which hosts important bauxite deposits. These bauxite ore deposits occur unconformably on the top of the lower Carboniferous marly carbonate sequence related to the Um Bogma Formation. The bauxite deposits are referred to as karst-type and consist of gibbsite, kaolinite, goethite, and hematite which increase stratigraphically upwards in horizons hosting the bauxitic–lateritic deposits. This study highlights the economic potential and environmental risks of REE-U enrichment in the Um Bogma karst terrain. Some trace elements such as Pb, Cu, Mo, As, Co, Ba, Zr, Cr, Zn, Ni, V, Y, Be, U, and REE occur in significant amounts in these bauxite deposits, in comparison with the worldwide bauxite deposits. The enrichment of REE and U results in significant concentrations reaching up to 1.45% and 0.19% respectively. The transport and adsorption of rare earth elements are related to the ion-adsorption type. SEM, EDX, and XRD investigations revealed that the REE immobilized in the form of authigenic LREE-bearing bastnaesite mineral which occurs as nest-, walnut-, rosy- and irregular-shaped grains adsorbed on iron oxides and clay minerals. The authigenic REE minerals significantly influence the shape of the REE patterns and induce weak positive Ce anomaly in the studied bauxite deposits. The chondrite-normalized REE patterns of the bauxite deposits indicate enrichment of LREE relative to HREE with weak Ce anomaly. The uranium minerals, umohoite, Zn-zippite, soddyite, uranophane, meta-autunite and uranopilite control the mobilized uranium within the karst profiles. The enrichment of REE suggests that oxidation conditions mostly immobilized Ce 4+ and transported REE 3+ downward to the lower horizons of the karst profiles. The high REE contents are mainly enriched in Fe-depleted bauxitic facies. While U and LREE are also concentrated in Fe-rich bauxites due to scavenging by goethite and clay minerals.

A clean method for alumina production and the coproduction of silicon-potassium compound fertilizer from middle and low grade bauxite ore

The global increase in the demand of aluminium raises the interest for the production from other alternative sources than Bauxite. Also, due to limited availability of bauxite ores in Nigeria, the use of kaolin as an alternative resource for alumina production, has become very vital. Therefore, the need for a more sustainable and optimised process is necessary to address these challenges. Hence, this research successfully developed a sustainable and efficient method for extracting high-purity alumina (Al2O3) from kaolin using an optimised acid leaching technique. The study began with the collection and preparation of kaolin sourced from Ilella in Sokoto State, Nigeria. The kaolin underwent calcination at 750°C to produce metakaolin. At 90°C, meta-kaolin was leached using 5M HCl acid, followed by filtration. The filtrate was then combined with 5M NaOH at 90°C to form sodium aluminate, a process that also removed magnesium and iron hydroxides. The pH of the solution was adjusted by adding HCl. The resulting aluminium hydroxide was calcined at 800°C and 900°C for two hours each, converting it into alumina. After calcination, the material was cooled to room temperature inside the furnace. The final alumina product was characterised using X-ray Fluorescence (XRF) and Scanning Electron Microscopy (SEM) to assess its composition and structure. It was observed that the percentage composition of Alumina was increased from 30.53% to 77.28% and 83.00% at calcination temperatures of 800°C and 900°C respectively. This established that Alumina can be extracted from Kaolin clay.

The importance of rare earth elements (REE) in high-end technology applications has become increasingly notable. Malaysia is rich in mineral resources like bauxite ore, which contains a significant amount of REE. However, REE from bauxite cannot be extracted directly without pre-treatments and the growing concerns of environmental pollution, such as red dust and red mud, are partially due to the increased stockpile of bauxite residue (BR). The study intends to compare the effect of pre-treatments before the REE leaching process of the RB from Felda Bukit Goh, Kuantan, Pahang. The methods 1 (M1) and 2 (M2) included roasting, magnetic separation, Bayer process, acid cracking, leaching via (NH4)2SO4, and precipitation via C2H2O4. In M2, lower current intensity in magnetic separation, a lower solid-to-liquid ratio and the absence of H2O2 in acid cracking were used. The RB contains light rare earth elements (LREE) between 190.20 to 318.71 mg/L with abundant cerium (Ce) and neodymium (Nd). The RB comprises of Fe2O3 44.66%, Al2O3 34.15%, TiO2 8.39% and SiO2 8.39% whereas gibbsite (Al(OH)3) was the main mineral. In M1, the REE contents decreased by 12.5% (301.31 mg/L) and between 0.4% to 8.4% after roasting and magnetic separation, respectively. Via the Bayer process, REE contents increased by 15.5% (346.81 mg/L) in M1, whereas decreased by 48.4% (119.34 mg/L) in M2. In acid cracking using H2SO4 with H2O2 in M1, the REE contents majorly remained in BR, while without H2O2 the REE contents decreased, indicating REE has been leached out in M2. The H2O2 caused the BR to become viscous and harder after drying, leading to the REE interlocking in the residue. The overall leaching performances in M1 and M2 were achieved at 1.34% and 99.0%, respectively, evidently showing that introducing H2O2 before the leaching process does not improve the REE extraction. Meanwhile, precipitation via C2H2O4, produced rare earth oxalate (REOx) up to 1.59 % in M1 and 31.80% in M2 where, based on element purity, the Ce and Nd in M2 attained were 92.78% and 7.20%, respectively.

Flotation separation of pyrite from high-sulfur bauxite remains challenging because of its high clay mineral content. To investigate the influence mechanisms of major clay minerals on pyrite flotation in high-sulfur bauxite, flotation tests were conducted under various conditions. Mineral liberation analysis revealed that kaolinite and illite collectively constitute ~95% of the clay minerals in a Henan high-sulfur bauxite ore. Flotation tests demonstrated their differential effects under acidic/alkaline conditions: In acidic pulp with 1×10⁻³ mol/L sodium butyl xanthate (SBX), the actual recovery (εa) of kaolinite/illite-pyrite pulp was 10% lower than the theoretical recovery (εT). Conversely, under alkaline conditions, εa exceeded εT by 15-20%. Analysis showed that under acidic conditions, opposite surface charges between kaolinite/illite and pyrite caused electrostatic adsorption, occupying SBX adsorption sites on pyrite. This reduced pyrite’s surface hydrophobicity and hindered hydrophobic agglomeration. Additionally, fine kaolinite/illite particles coated pyrite surfaces, blocking SBX adsorption and weakening collection efficiency. Under alkaline conditions, dissolved substances from kaolinite/illite inhibited hydrophilic substance formation on pyrite surfaces, freeing more SBX adsorption sites. Furthermore, some kaolinite/illite particles adsorbed onto pyrite surfaces and floated as "carriers" with pyrite, resulting in higher εa than εT in alkaline environments.

Production of hydrogen-rich gaseous product from pyrolysis of polypropylene wastes using bauxite ore catalyst: yield analysis of various products

One-Step Calcification–Biomaterialization Transformation Process for Treating High-Iron Bauxite Ore

ABSTRACTThis paper reviews technologies being developed toward material circularity and manufacturing sustainability in the automotive industry; aluminum sustainability is used herein as an exemplar. While aluminum is increasingly used for lightweighting applications in the transportation industries to reduce energy consumption and carbon footprint, primary production of aluminum is energy‐intensive with significant CO2 emissions. However, remelting aluminum scrap only uses ~5% of the energy, resulting in significantly reduced emissions required to produce primary aluminum from bauxite ore. The wide use of recycled aluminum for transportation applications will ensure the sustainability of the supply chain. Another example is the use of renewable wood materials such as the recently developed “super wood” which is a densified natural wood with similar mechanical properties to metallic materials. For manufacturing processes, the development and evolution of energy‐efficient large thin‐wall die casting (also called mega/giga casting) will enhance the sustainability of automotive manufacturing. Alternative energy vehicles tend to have more simplified body structures, enabling the use of large and consolidated castings which significantly reduce welding, joining, and assembly operations. Reclaiming some of the high‐value battery materials from electric vehicles is challenging. A patented “Hydro‐to‐Cathode” direct precursor synthesis process can leach out impurities, keeping the valuable metals in solution and eliminating multiple steps in the recycling flow. Additional technology advances are required to reclaim other materials. Ultimately, the combination of recycled/renewable materials and energy‐efficient manufacturing processes will drive the automotive industry toward circularity and sustainability.

Bauxite refinery residue (red mud) is a solid by-product of the alumina refinery industry in which bauxite ore undergoes Bayer Process to produce alumina, which is then converted into aluminium. In fact, the amount of red mud (RM) is numerous, for each ton of alumina product yields 1 to 2 tons of RM. RM is a caustic material (pH 10-13) and carries valuable metals and minerals. Its disposal entangles intricate processes thus, conventional disposal practices comprise depositing it in open dams. The volume of RM continues to accumulate, and these acts possess the potential disaster to harm both environmental along with human health. Previous studies have show RM as environmental remedies, particularly for CO2 capture from flue gas. This study examines the RM originated from Indonesia to neutralize using active wet carbonation technique. The RM-cake-clay-form with 25.5% water content is transformed into a 40% solid content slurry then contacted using CO2 industrial grade at room temperature and atmospheric pressure at gas flowrate 5 L/min for 120 min. According to the study that has been conducted, CO2 showed its potential to neutralized the RM alkalinity from pH 11.25 to 7.44 and generate mineral-carbonate compounds with estimated sequestration capacity 1.424 g CO2/100 g RM from the obtained carbonated filtrate through bicarbonate and carbonate ion presence.

ABSTRACTBauxite residue is an industrial by‐product generated during alumina production from bauxite ore through the Bayer process. The worldwide stockpiles of bauxite residue are expected to reach 10 billion tons by 2050 if not processed effectively. Limited industrial‐scale processing (3%–4%) of bauxite residue is mainly due to complex physical and chemical characteristics. High alkalinity and multiple elements make the recycling process complicated and expensive. The following work presents a hydrometallurgical process for effectively recycling bauxite residue to recover high‐purity metal oxide products, including magnetite, alumina, titanium dioxide, and scandium oxide. Bauxite residue is first neutralized after leaching with mild hydrochloric acid, followed by the leaching of iron with oxalic acid and photochemical reduction of leach liquor to obtain ferrous oxalate precipitate, which is further converted to high‐purity magnetite. A pyrometallurgical method is also discussed based on smelting for pig iron extraction and subsequent slag processing for value recovery. A comparative analysis of hydro and pyrometallurgical processes is carried out to highlight the key differences and potential for large‐scale applications.

The Sanandaj–Sirjan Zone and Zagros Fold–Thrust Belt in Iran host numerous Mediterranean-type karst bauxite deposits; however, their formation mechanisms and critical raw material potential remain ambiguous. This study combines mineralogical and geochemical analyses to explore (1) the formation of authigenic minerals, (2) the role of microbial organic processes in Fe cycling, and (3) the assessment of their critical raw materials potential. Mineralogical analyses of the Late Cretaceous Daresard and Middle–Late Permian Yakshawa bauxites reveal distinct horizons reflecting their genetic conditions: Yakshawa exhibits a vertical weathering sequence (clay-rich base → ferruginous oolites → nodular massive bauxite → bleached cap), while Daresard shows karst-controlled profiles (breccia → oolitic-pisolitic ore → deferrified boehmite). Authigenic illite forms via isochemical reactions involving kaolinite and K-feldspar dissolution. Scanning electron microscopy evidence demonstrates illite replacing kaolinite with burial depth enhancing crystallinity. Diaspore forms through both gibbsite transformation and direct precipitation from aluminum-rich solutions under surface conditions in reducing microbial karst environments, typically associated with pyrite, anatase, and fluorocarbonates under neutral–weakly alkaline conditions. Redox-controlled Fe-Al fractionation governs bauxite horizon development: (1) microbial sulfate reduction facilitates Fe3⁺ → Fe2⁺ reduction under anoxic conditions, forming Fe-rich horizons, while (2) oxidative weathering (↑Eh, ↓moisture) promotes Al-hydroxide/clay enrichment in upper profiles, evidenced by progressive total organic carbon depletion (0.57 → 0.08%). This biotic–abiotic coupling ultimately generates stratified, high-grade bauxite. Finally, both the Yakshawa and Daresard karst bauxite ores are enriched in critical raw materials. It is worth noting that the overall enrichment appears to be mostly driven by the processes that led to the formation of the ores and not by the chemical features of the parent rocks. Divergent bauxitization pathways and early diagenetic processes—controlled by paleoclimatic fluctuations, redox shifts, and organic matter decay—govern critical raw material distributions, unlike typical Mediterranean-type deposits where parent rock composition dominates critical raw material partitioning.

As industrialization accelerates, the demand for metals, particularly aluminium, continues to rise. This growth has also led to an increase in by-products from the bauxite ore refining process, namely red mud. The highly alkaline nature of red mud, combined with its heavy metal content, poses significant environmental challenges. However, red mud also contains rare earth elements (REEs) that can serve as valuable secondary resources. An environmentally friendly approach to recovering these metals is phytomining, which utilizes plants and simultaneously contributes to land remediation. This study aims to evaluate the potential of Imperata cylindrica in metal recovery and the remediation of red mud waste. The research began by conditioning the pH of red mud through the addition of citric acid, fertilizers, and by adjusting the red mud composition to levels of 40% based on the optimum result using Response Surface Methodology. Phytomining was initiated once the pH of the substrate (a mixture of red mud and soil) reached an optimal range of 8.0–8.5. The results demonstrated that Imperata cylindrica was capable of absorbing several rare earth metals, including gadolinium (Gd), neodymium (Nd), and cerium (Ce), with concentrations of 119.5 mg/kg, 16.5 mg/kg, and 6.67 mg/kg, respectively, in its roots. Additionally, the plant showed the ability to absorb major components such as iron (Fe) and titanium (Ti), with the metals distributed throughout the plant's roots, stems, and leaves.

Red mud (Bauxite residue) is an industrial by-product (IBP) generated as a vast volume, mainly from aluminum industries. Disposal of red mud (RM) in open land leads to serious environmental hazards, occupies a vast land area, and incurs enormous economic and social costs. Storage and maintenance of red mud dumps are also costly, and their failures frequently flood vast areas, killing people and cattle and disrupting the ecosystem. Conversely, research data shows that the red mud has enormous potential to transform its valuable resources. Due to the growing demand for bauxite ore for aluminum industries, the volume of red mud has been increasing rapidly, causing an inevitable multidirectional consequence in the context of environmental and sustainability issues. On the other hand, the rising demand and resource crises continue to deplete natural resources; the gap of enormous resource availability has become a severe challenge for scientists, researchers, and institutional R&amp;D to develop a process technology to re-generate resources through the recycling of wastes. Using red mud through the circular economy concept can replenish the depletion of virgin resources (mainly the construction sector) and extract valuable materials and metals from red mud. Recycling RM through the circular business model can increase the sustainability of natural resources, reduce environmental pollution, water contamination, and land pollution, increase land area, replenish the depletion of natural resources, enhance economic growth, and mitigate global warming and climate change.

Background A surge in illegitimate mining is threatening the legitimacy of mining industries such as bauxite mining in Awaso. An awareness of radioactivity problems is essential when evaluating any application. Public perceptions and apprehensions regarding risks associated with mining activities must be acknowledged. Objective The primary aim is to evaluate the radioactivity in water and soil from the Sefwi Awaso bauxite mine and its surroundings, as well as to determine the health risks to mine workers and the local population. Methods Mining residues from the bauxite mine and surrounding area were analyzed for radioactive concentrations using direct gamma-ray spectrometry with a high purity germanium detector. Genie-2000 program was used for qualitative analysis of radionuclide. Results Soil, bauxite ore, and red mud all had different concentrations of 226Ra, 232Th, and 40K based on their respective activities, thus: (29 ± 3.2) Bq kg-1, (32 ± 4) Bq kg-1, and (179 ± 18) Bq kg-1; (39 ± 4) Bq kg-1, (97 ± 11) Bq kg-1, and (15 ± 2) Bq kg-1; (45 ± 5) Bq kg-1, (64 ± 7) Bq kg-1, and (125 ± 19) Bq kg-1. In the community water samples, the average activity concentrations of 226Ra, 232Th, and 40K were (1.0 ± 0.9) Bq l-1, (3.2 ± 0.6) Bq l-1, and (16 ± 5) Bq l-1, respectively, which are all well within the global average activity concentrations. The committed effective dose was 0.63 ± 0.08 mSv, and annual effective dose estimates for the mine and community were (75 ± 5) µSv and (26 ± 3) µSv, respectively. Conclusion The bauxite mining operation does not significantly increase activity concentrations, suggesting an annual dose increase well below the 1 mSv y-1 limit for public exposure.

Integrated waste reduction by production of bio-magnetic adsorbents via copyrolysis of waste red mud and residual sugar beet pulp: Target zero waste.