Bauxite Deposits Research Articles

Analysis of ASTER data for mapping bauxite rich pockets within high altitude lateritic bauxite, Jharkhand, India

Bauxite deposits of Jharkhand in India are resulted from the lateritization process and therefore are often associated with the laterites. In the present study, ASTER (Advanced Space borne Thermal Emission and Reflection Radiometer) image is processed to delineate bauxite rich pockets within the laterites. In this regard, spectral signatures of lateritic bauxite samples are analyzed in the laboratory with reference to the spectral features of gibbsite (main mineral constituent of bauxite) and goethite (main mineral constituent of laterite) in VNIR–SWIR (visible-near infrared and short wave infrared) electromagnetic domain. The analysis of spectral signatures of lateritic bauxite samples helps in understanding the differences in the spectral features of bauxites and laterites. Based on these differences; ASTER data based relative band depth and simple ratio images are derived for spatial mapping of the bauxites developed within the lateritic province. In order to integrate the complementary information of different index image, an index based principal component (IPC) image is derived to incorporate the correlative information of these indices to delineate bauxite rich pockets. The occurrences of bauxite rich pockets derived from density sliced IPC image are further delimited by the topographic controls as it has been observed that the major bauxite occurrences of the area are controlled by slope and altitude. In addition to above, IPC image is draped over the digital elevation model (DEM) to illustrate how bauxite rich pockets are distributed with reference to the topographic variability of the terrain. Bauxite rich pockets delineated in the IPC image are also validated based on the known mine occurrences and existing geological map of the bauxite. It is also conceptually validated based on the spectral similarity of the bauxite pixels delineated in the IPC image with the ASTER convolved laboratory spectra of bauxite samples.

Discovery and preliminary study of the high tungsten and lithium contents in the Dazhuyuan bauxite deposit, Guizhou, China

Bauxite in China remains an urgently needed resource largely dependent on imports. Based on the study of the newly-discovered Dazhuyuan bauxite deposit in northeastern Guizhou, we have found new enrichment of tungsten and lithium in bauxite, with the highest WO3 content up to 0.33% and the highest Li2O content up to 0.58%. The present paper reports the initial result, and the spatial distribution feature of W and Li in the ore body (with Li enriched mostly in the north part of the west limb of the Liyuan syncline, whereas W enriched mostly in the central part of the east limb). The results suggest that it is necessary to delineate lithium and tungsten ore body independently, discuss the feasibility of its industrial utilization, and point out the new direction of synthetic appraisal for such kinds of traditional mineral resources, in order to forecast and assess bauxite resources in the region.

Characterization of bauxite deposits from Kachchh Area, Gujarat

The bauxites deposits of Kachchh area in Gujarat are investigated to characterize them based on mineralogical and petrographic studies. The major bauxitic mineral in these occurrences is gibbsite, with minor concentration of boehmite and diaspore. Apart from the bauxitic minerals, the other associate minerals are kaolin, calcite, alunite and the iron ore minerals such as hematite and goethite and titanium rich anatase. The iron ore minerals (hematite and goethite) are 10-50microns in size and are disseminated throughout the oolitic and pisolitic bauxitic minerals. At places the goethite exhibits colloform texture. The preservation of basaltic texture in some of the samples indicate that the insitu nature of these bauxites, which are formed by the alteration of calcic plagioclase from the parent basalt. Although, the basalt occurs as the main parent rock for these bauxites, the presence of calcite in some of the samples represent the possibility of having a limestone parent rock at least in some of the bauxite occurrences.

Dynamic models of lateritic bauxite formation

2D dynamic models of bauxite formation in the weathering mantle covering denudation areas drained by river systems are discussed. The role of relief-forming factors (tectonic uplift, river erosion and denudation of drainage divides), the interrelation of hydrogeological and lithologic structure of the bauxitebearing weathering mantle, and the dynamics of zoning formation above and below groundwater level are described in the models. Creative and destructive epochs of lateritic bauxite formation differing in tectonic regime are distinguished. During the creative epochs, lateritic weathering develops against a background of decreasing denudation and an increase in areas of bauxite formation. The destructive epochs are characterized by intense denudation, cutting down the areas of lateritic bauxite formation and eventually leading to the complete removal of the weathering mantle. Different morphogenetic types and varieties of bauxite-bearing weathering mantles develop during creative and destructive epochs. The morphology of the weathering mantle sections at the deposits of Cenozoic lateritic bauxite in the present-day tropical zone of the Earth corresponds to the destructive epoch, which is characterized by declining areas of lateritic bauxite formation and will end with complete denudation of lateritic bauxite.

A study on Pb isotopic characteristics of raw bauxite in western Guangxi, China

The Pb isotopic composition of ores is one of the important approaches to trace the ore sources. It has not yet been applied to research on bauxite ore so far. The current research on bauxite deposits in western Guangxi, China, seldom focuses on raw bauxite and studies on raw bauxite are mostly at macro-level. This study is the first to apply Pb isotope data to tracing bauxite ore sources. The Pb isotopic compositions of ore and rock samples from the Nadou and Taiping mining districts are projected on the Doe and Zartman plumbotectonic models and the results showed that the ore resources are different for the two mines.

Development of fireclay aluminosilicate refractory from lithomargic clay deposits

Lithomargic clay until now has not been utilised to produce refractory bodies due to its low plasticity. In this work, the development and evaluation of fireclay refractory material produced from lithomargic clay deposit has been studied by addition of clay binder. Three formulations were prepared by mixing, semi-dry moulding, drying and firing at temperatures ranging from 1200 to 1400°C. The fired samples were investigated to determine their physical properties such as bulk density, apparent porosity, linear firing shrinkage, and cold crushing strength. The chemical and mineralogical compositions were also determined. The results show that the linear firing shrinkage values were within limits acceptable for refractory clays. The cold crushing strength increases as temperature increased to 1400°C. Cold crushing strength increased with increasing binder content. The increase of the highly refractory phases (cristobalite and mullite) and the densification of the bricks due to the presence of fluxing agents were responsible for the high cold crushing strength values. The investigated properties indicate that lithomargic clay underlying bauxite deposits could be used to produce fire clay aluminosilicate refractories.

Mineralogical and geochemical studies of boron-rich bauxite ore deposits in the Songqi region, SW Henan, China

The Songqi region, SW Henan, is an important bauxite province in China. The bauxite ore deposits occur unconformably on the top of Middle Ordovician argillaceous carbonates. The bauxite ores from the Songqi region are characterized by unusually high boron contents. In this paper, we report the mineralogical and chemical compositions of selected bauxite ores from the region. These new data, together with existing geochemical data of soils in the region, are used to evaluate the origin of boron enrichment in the bauxite ores. The compositional characteristics of tourmaline in the bauxite ores suggests that this mineral was likely derived from a meta-sedimentary protolith. Mass balance calculation reveals that tourmaline only accounts for a small portion of boron in the bauxite ores; the majority of boron in the ores must occur in other forms, possibly by ion absorption on the surfaces of diaspore and clay minerals. In the Songqi region, the Precambrian meta-sedimentary rocks are known to contain abundant tourmalines whereas the Cambrian–Ordovician argillaceous carbonates and the Upper Proterozoic shales are all enriched in boron in free ion state. We suggest that these rocks provided tourmaline and boron ion to the bauxite deposits in the region. Most known bauxite deposits in the Songqi region occur at the margins of boron-rich soil domains, suggesting that boron in soils is a potential exploration indicator for unknown bauxite deposits in this region.

Mineralogical characteristics of the superlarge Quaternary bauxite deposits in Jingxi and Debao counties, western Guangxi, China

In recent decades, more than 0.5 billion tons of ores scattered in the Quaternary laterite in western Guangxi, China have been explored. The ores were derived from a bauxite horizon in Permian via physical break-up and re-sediment process. Utilizing various test methods, i.e., XRD, DTA, TG/DTG, SEM/EDS and EPMA, the mineralogical characteristics of the Quaternary bauxite ores in Jingxi and Debao counties were investigated. XRD was used together with TG/DTG to obtain relatively accurate ore mineral abundance. Diaspore is the major phase, whereas hematite, kaolinite, anatase, chamosite, gibbsite, goethite, illite and rutile are minor. Diaspore is characterized by a small particle size, low degrees of crystallinity and complex chemical composition. Both gibbsite and goethite have a varied particle size, and goethite crystals contain high Al substitution and Si. It is clarified that diaspore, chamosite and anatase were formed in a mildly reduced and alkaline depositional environment in Permian, while gibbsite, hematite, goethite and part kaolinite were precipitated from Al3+-, Si4+- and Fe3+-enriched solutions within an Quaternary oxidized environment. The ions Al3+, Si4+ and Fe3+ are mostly released from chamosite in its dissolution process. The different physicochemical conditions between the Permian depositional and the Quaternary weathering periods resulted in a complex mineral assemblage in the Quaternary bauxite.

Geological, geochemical, and mineralogical characteristics of the Mandan and Deh-now bauxite deposits, Zagros Fold Belt, Iran

The Mandan and Deh-now bauxite deposits are located 40km northeast of the Dehdasht city in the Zagros simply fold belt. These deposits occur in eroded major NW–SE trending anticlines and occupy karst cavities near or at the boundary between the Sarvak and Ilam Formations. Local uplifts at the end of the Cenomanian and the mid-Turonian caused erosion and karstification of the Sarvak Formation. These unconformities in the Upper Cretaceous favoured the formation and enrichment of bauxite deposits in the Zagros fold belt. The bauxite sequence in the Mandan deposit consists of white, gray, black, pisolitic, red, and yellow bauxites. This sequence was repeated in the Deh-Now area, but without gray and black bauxites. The present mineralogical studies of the Sarvak Formation and the Mandan and Deh-now bauxite deposits indicate oxidizing to reducing conditions during the Upper Cretaceous in the Zagros fold belt, which had a significant effect on the compositions of the bauxites. At least two phases of bauxitization can be distinguished in the study area: (i) an oxidizing phase represented by boehmite, diaspore, hematite and kaolinite; and (ii) a reducing phase represented by pyrite and chlorite. Geochemical data show that trace elements, like Zr, Hf, Nb, Ta, Th, and U, were enriched during bauxitization. The bauxite deposits and carbonate rocks show similar REE patterns, namely they are enriched in REEs although the LREEs are more enriched than the HREEs. Mass change calculations demonstrate that Mg, Mn, Ca, K, and P2O5 were leached out of the weathered system whereas Al, Fe, and Si become concentrated in the residual system. This study indicates that the Mandan and Deh-now deposits are karst-type bauxites formed by karstification and weathering of the Sarvak Formation.

Geochemical discrimination of Early Palaeogene bauxites in Croatia

Two discriminant function models were created in order to distinguish between major- and trace-element geochemical patterns typical of Lower Palaeogene (Palaeocene, Pc) bauxites formed on the portion of the carbonate platform comprising the Karst or External Dinarides. Four groups of bauxites from Istria, North Adriatic Islands, North Dalmatia and Central Dalmatia have been distinguished, according to their specific combinations of major and trace elements, characteristic conditions of formation?, and processes prevailing in the karst environment during subaerial exposure of the carbonate platform. Typically, in both models the first discriminant function explains most of the system variability. However, the trace-element model proves itself as a more helpful predictive tool, representing the straightforward example of classification of the samples into four pre-defined groups of Pc bauxites. Generally, both models follow a characteristic trend in geochemical signature related to the recent geographical position of the bauxite deposits, namely a decrease in K2O and an increase in the Cr content in a SE direction (from Istria to Dalmatia). This was most probably the result of environmental conditions during the AdCP Cretaceous-Palaeogene emergent stage (Istria), and emplacement of parent rocks (ophiolite belt) supplying the necessary material for bauxite genesis (Central Dalmatia).

Anthropology of displacement: Case of conservation induced displacement and its impact on indigenous people in Simlipal Tiger Reserve, Odisha

Displacement is a growing concern in globalized world; it is said that for any development project the cost has to necessarily be borne by the displaced and affected population. In the state of Odisha, particularly where displacement due to development projects are rampant, of late the foreign investors have identified the low, flat-topped mountains buried with some high deposits of the best quality bauxite in the world. According to estimates, the buxite makes more than two trillion dollars, that is, twice the value of India's GDP, $1.243 trillion in 2009 (Padal and Das 2010) Therefore, to construct infrastructural projects such as multipurpose river valley, mining, industrial, sanctuaries, national park etc.) in the forest areas, the state at present has been diverging maximum forest lands, while displacing more than lakhs of age old forest dwellers. They are the ones who pay the price and get displaced from everything attached to them. This paper tries to explore the impact of conservation induced displacement in Simlipal Tiger Reserve and the Resettlement & Rehabilitation practices in the Kapanda Banbasa & Ambadiha resettlement colony using some of the anthropological methods and approaches.

Biomineralization and magnetic and thermal properties of the iron concretion from the laterite bauxite deposit of Bao Lok, South Vietnam

Biomineralization and magnetic and thermal properties of the iron concretion from the laterite bauxite deposit of Bao Lok, South Vietnam

Ground air of the bauxite-bearing lateritic weathering crust (Republic of Guinea)

The ground air of the bauxite deposit in West Africa was tested for its chemical composition. The obtained data provide the first insight into the air effect on the mineralogical-geochemical zoning of the lateritic weathering profile. The air was tested in areas with different geomorphologic features, which allowed us to study the effect of relief and landscape on the ground-air formation.

The metallogenic evolution of the Greater Antilles

The Greater Antilles host some of the world’s most important deposits of bauxite and lateritic nickel as well as significant resources of gold and silver, copper, zinc, manganese, cobalt and chromium. Beginning in Jurassic time, sedimentary exhalative base metal deposits accumulated in marine sedimentary rift basins as North and South America drifted apart. With the onset of intraoceanic subduction during the Early Cretaceous, a primitive (tholeiitic) island arc formed above a southwesterly-dipping subduction zone. Podiform chromite deposits formed in the mantle portion of the supra-subduction zone, directly above subducted Proto-Caribbean oceanic lithosphere. Within the nascent island arc, bimodal-mafic volcanogenic massive sulfide deposits formed in a fore-arc setting; mafic volcanogenic massive sulfide deposits formed later in mature back-arc basins. The Pueblo Viejo gold district, with five million ounces in production and twenty million ounces in mineable reserves, formed at 108-112Ma, in an apical rift or back-arc setting. By Late Cretaceous time, calc-alkaline volcanism was well established along the entire length of the Greater Antilles. Volcanogenic massive sulfide deposits including shallow submarine deposits characteristic of the primitive island arc gave way to porphyry copper and epithermal precious metal deposits typical of the mature island arc. Oblique collision of the Greater Antilles with North America began in the Late Cretaceous in Cuba and migrated eastward. Orogenic gold and tungsten deposits that formed during the collision event are preserved in ophiolites and in metamorphic core complexes. Since the Eocene, regional tectonism has been dominated by strike-slip motion as the North American continent moved westward relative to the Caribbean Plate. Large nickel-cobalt laterite deposits were formed when serpentinites were exposed to weathering and erosion during the mid-Tertiary. Bauxite deposits were derived from the weathering of volcanic ash within a carbonate platform of Eocene to Miocene age

Bauxite Deposits in China; High Aluminous Shale

Bauxite Deposits in China; High Aluminous Shale

Mineralogy, spread, and use of bauxites

Rock-forming high-aluminous, associated, and accessory (the most common) bauxite minerals were described in detail, along with their corresponding diagnostic variables, chemical composition, and spread. A geological-economic overview of the world bauxite ore deposits and reserves was presented, and the specific features of Russian bauxite deposits and practical value of bauxites were discussed.

Lanthanoids as an indicator of the structure of the zone of free alumina in the lateritic weathering crust of the KMA

666 Large bauxite deposits playing an important role in the economic development of the Russian Federation were discovered and studied in detail during the long history of the development of domestic geology. In addition to aluminum, rare hydrolyzer elements and REEs are accumulated during lateritic weathering; they are of special importance as well, since the quan� titative data on their concentration may be applied for bauxite processing (in perspective). Indicative possibilities of lanthanoids were consid� ered in the studies of V.I. Sirotin, V.A. Shatrov, and E.E. Belyavtseva from the example of the lateritic (alumina) weathering crust of the KMA [1–3]. In this paper we analyze the relationship between the litho� logical types of bauxites and the distribution of lanth� anoids in them (on the example of the sections of the largest Vislovskoe deposit). The zone of free alumina includes three subzones: the lower allitic, conditional bauxites, and debauxiti� zation. Rather than the lateritic stage of the profile his� tory, such a structure reflects the lateritic–diagenetic stage, when the separation of a single zone of laterite into subzones occurred [4, 5], which was accompanied by migration of iron and silicon in the profile. Alumi� num was poorly mobile: its migration was limited to zone IV and the upper part of zone III. As a result, sometimes zone IV was completely replaced by kaolinite (gley process) and shamosite (iron introduc� tion), but most often zone IV was separated into the three subzones mentioned.

Orebody vertical structure and implications for ore-forming processes in the Xinxu bauxite deposit, Western Guangxi, China

The Xinxu bauxite orebodies, which are contained in Quaternary depressions overlying strata of Permian to Devonian age, were formed through the break-up, oxidation and re-sedimentation of a pre-existing Permian bauxite horizon. With progressive karsitification, the underlying strata of the Quaternary orebodies were eroded out downwards in sequence, gradually transiting from Permian to Devonian. Thus an older underlying stratum generally infers a higher degree of weathering. A total of 47 exploration wells, sampled each meter, were chosen from several orebodies to evaluate the vertical distribution of four major components (Al 2O 3, Fe 2O 3, SiO 2 and loss-on-ignition) in the ores. The vertical evenness is quantified via a box-gliding multifractal model. The small width of the multifractal spectrum suggests that the vertical ore quality is even overall, indicating an intertwining break-up and mixing up processes during evolution of the Quaternary orebody. Although the four components show complex spatial distributions, topographic elevation displays a positive relationship with the mean Fe 2O 3 content, and a negative correlation with the vertical unevenness of Al 2O 3 and Fe 2O 3 in the wells. This is taken to reflect the more uniform oxidizing environment in the higher depressions, which facilitates a homogeneous and greater increase of Fe 2O 3 content throughout the orebody. In contrast, the redox conditions in lower depressions are less oxidizing and varied in space, inducing great variation in degree of Fe 2O 3 increase in the ores. This study also demonstrates that, in the Xinxu deposit, the ore-forming redox environment has more impact on the ore quality than the degree of weathering. As the contents show irregular vertical changes in the lower depressions, it follows that it is the ancient redox environment rather than the modern conditions which affect the orebody vertical structure. This clarifies the fact that the vertical structure of the orebody is jointly constrained by the physical mélange accumulation of ores and the differences between the ancient redox environments in the higher and lower locations. These factors should be the primary factors affecting the vertical structure of karst bauxite deposits.

The geomicrobiology of bauxite deposits

Bauxite deposits are studied because of their economic value and because they play an important role in the study of paleoclimate and paleogeography of continents. They provide a rare record of the weathering and evolution of continental surfaces. Geomicrobiological analysis makes it possible to verify that microorganisms have played a critical role during the formation of bauxite with the possibility already intimated in previous studies. Ambient temperature, abundance of water, organic carbon and bioavailable iron and other metal substrates provide a suitable environment for microbes to inhabit. Thiobacillus, Leptospirilum, Thermophilic bacteria and Heterotrophs have been shown to be able to oxidize ferrous iron and to reduce sulfate-generating sulfuric acid, which can accelerate the weathering of aluminosilicates and precipitation of iron oxyhydroxides. Microorganisms referred to the genus Bacillus can mediate the release of alkaline metals. Although the dissimilatory iron-reducing and sulfate-reducing bacteria in bauxites have not yet been identified, some recorded authigenic carbonates and “bacteriopyrites” that appear to be unique in morphology and grain size might record microbial activity. Typical bauxite minerals such as gibbsite, kaolinite, covellite, galena, pyrite, zircon, calcium plagioclase, orthoclase, and albite have been investigated as part of an analysis of microbial mediation. The paleoecology of such bauxitic microorganisms inhabiting continental (sub) surfaces, revealed through geomicrobiological analysis, will add a further dimension to paleoclimatic and paleoenvironmental studies.

Comparison of microbial communities in pilot-scale bioreactors treating Bayer liquor organic wastes

Western Australian bauxite deposits are naturally associated with high amounts of humic and fulvic materials that co-digest during Bayer processing. Sodium oxalate remains soluble and can co-precipitate with aluminium hydroxide unless it is removed. Removal of sodium oxalate requires a secondary crystallisation step followed by storage. Bioreactors treating oxalate wastes have been developed as economically and environmentally viable treatment alternatives but the microbial ecology and physiology of these treatment processes are poorly understood. Analysis of samples obtained from two pilot-scale moving bed biofilm reactors (MBBRs) and one aerobic suspended growth bioreactor (ASGB) using polymerase chain reaction- denaturing gradient gel electrophoresis of 16S rRNA genes showed that members of the α-, β- and γ-Proteobacteria subgroups were prominent in all three processes. Despite differing operating conditions, the composition of the microbial communities in the three reactors was conserved. MBBR2 was the only configuration that showed complete degradation of oxalate from the influent and the ASGB had the highest degradation rate of all three configurations. Several strains of the genus Halomonas were isolated from the bioreactors and their morphology and physiology was also determined.