Lateritic Deposits Research Articles

Uranium isotopic evidence for the origin of the Bahariya iron deposits, Egypt

The economic iron ore deposits of Egypt are located at Bahariya Oasis in the Lower Middle Eocene limestone. The main iron minerals are goethite, hematite, siderite, pyrite, and jarosite. Manganese minerals are pyrolusite and manganite. Gangue minerals are barite, glauconite, gibbsite, alunite, quartz, halite, kaolinite, illite, smectite, palygorskite, and halloysite. Geochemical comparison between the ore and the Nubia sandstone showed that the ore is depleted in the residual elements (Al, Ti, V, and Ni) and enriched in the mobile elements (Fe, Mn, Zn, Ba, and U) which indicates that the Bahariya iron ore is not a lateritic deposit despite the deep weathering in this area. On the other hand, the Nubia sandstone showed depletion in the mobile elements, which demonstrates the leaching process in the Nubia Aquifer. The presence of such indicator minerals as jarosite, alunite, glauconite, gibbsite, palygorskite, and halloysite indicate that the ore was deposited under strong acidic conditions in fresh water. Isotopic analyses of the uranium in the amorphous and crystalline phases of the ore, in the country rocks, and dissolved in the Nubia Aquifer water, all support the conclusion that U and Fe were precipitated together from warm ascending groundwater. U and Fe display strong co-variation in the ore, and the 234U/ 238U activity ratio of the newly precipitated U in the country rock and the leached component of U in the groundwater are identical. There is only slightly more uranium in the amorphous phase than in the crystalline and only a slightly lower 234U/ 238U activity ratio, suggesting that the iron in the two phases have a similar origin. Comparison of the excess 234U in the water and in the total ore leads to the conclusion that the precipitation of the U, and by inference the iron, occurred within the last million years. However, that both precipitation and leaching of U have occurred over the last 300,000 years is evidenced by the extreme 230Th/ 234U disequilibria observed in some of the samples. Some of the amorphous depositional events have been very recent, perhaps within the last 10,000 years.

Relationships between regolith materials, petrophysical properties, hydrologeology and supergene Ni enrichment at the Cawse Ni-laterite deposits, Western Australia: Implications for exploring with AEM

In the Eastern Goldfields of Western Australia, airborne electromagnetic (AEM) data have been acquired over areas prospective for nickeliferous laterite deposits, although their application in exploring for this style of mineralisation is not well understood. In part, this can be attributed to a lack of detail concerning relationships between supergene Ni enrichment and the petrophysical, particularly electrical, properties associated with prospective regolith materials and settings. This issue was addressed using a combination of multi-parameter borehole geophysical techniques and lab analysis of mineralogy, geochemistry and soluble salt content for 24 drill holes in a zone of known mineralisation associated with the Cawse lateritic Ni deposits, located in the Eastern Goldfields, W.A. The regolith associated with supergene Ni enrichment exhibited a complex vertical conductivity structure. In places, elevated conductivities were coincident with Ni-Mn-Co mineralisation. These correlations were noted to occur at hydromorphic barriers associated with structural discontinuities or in places where regolith textural changes were marked. The observed regolith electrical structure was indicative of contemporary groundwater processes, with higher conductivities associated with concentrations of soluble salts. Results suggest that AEM data could be used as an exploration tool particularly to locate structurally controlled conductivity contrasts that may be associated with Ni enrichment.

Relationship Between Regolith Materials, Petrophysical Properties, Hydrologeology and Mineralisation at the Cawse Ni Laterite Deposits, Western Australia: Implications for Exploring with Airborne EM

In the Eastern Goldfields of Western Australia, airborne electromagnetic (AEM) data have been acquired over areas prospective for nickeliferous laterite deposits, although their application in exploring for this style of mineralisation is not well understood. In part, this can be attributed to a lack of detail concerning relationships between supergene Ni enrichment and the petrophysical, particularly electrical, properties associated with prospective regolith materials and settings. This issue was addressed using a combination of multi-parameter borehole geophysical techniques and laboratory analyses of mineralogy, geochemistry and soluble salt content for 24 drill holes in a zone of known mineralisation associated with the Cawse lateritic Ni deposits, located in the Eastern Goldfields, W.A.The regolith associated with supergene Ni enrichment exhibited a complex vertical conductivity structure. In places, elevated conductivities were coincident with Ni-Mn-Co mineralisation. These correlations were noted to occur at hydromorphic barriers associated with structural discontinuities, or in places where regolith textural changes were marked. A better understanding of the complex spatial patterns associated with the electrical character of the regolith at Cawse, was achieved by examining the weathered profile as a set of hydrostratigraphic units, namely the transported cover, zone of illuviation and in situ regolith. This framework allows the observed regolith electrical structure to be explained in terms of contemporary groundwater processes and the accumulation of soluble salts.The observed petrophysical (electrical) response of the regolith at Cawse suggests that AEM has a role in locating impermeable barriers and faults which may, respectively, represent sites for shallow, high grade Mn-Co-Ni and garnierite mineralisation, particularly where they are coincident with local accumulations of soluble salt and moisture.

Syerston nickel–cobalt–platinum project

The Syerston project comprises the development, mining and processing of nickel, cobalt and platinum resources in the central-west region of New South Wales, Australia, some 400 km northwest of Sydney. Wholly operated by Black Range Minerals, Ltd. (listed on the Australian Stock Exchange), Syerston will be a significant force in the Australian cobalt industry, producing approximately 4000 t/year cobalt for 20 years. Nickel production is initially projected at 18 500 t/year at an operating cost of $U.S.(0.18)/lb after cobalt credits. Recovery of 10 000-15 000 oz/year by-product platinum by gravity and magnetic separation has not yet been factored into the project economics.A detailed bankable feasibility study, which was funded by a $Aus.10 000 000 facility provided by CIBC Capital Partners of Toronto, Canada, and completed in June, 2000, confirmed Syerston's robust technical and financial viability as the best of the second-generation laterite deposits using pressure acid-leach technology. The capital cost is projected at $Aus.629 000 000 (including refinery).The status of the project in November, 2000, was as follows. The company was engaged in parallel negotiations with major industry partners and major banks for project debt. Parties offering completion support and/or seeking offtake agreements for cobalt production had been invited to analyse the project feasibility data and negotiations were under way. A detailed environmental impact statement had been produced for public comment and no issues had emerged that might delay approval. Likewise, there were no native title issues that could curtail development. Following assessment of tenders for the engineering procurement and construction management, which had been submitted by many engineering groups, the expectation was that construction would commence in the second quarter of 2001, followed by starts of ore commissioning in mid-2003, ramp-up production at the end of 2003 and full production in mid-2005.Syerston has the advantage of learning from the first generation of Western Australian nickel laterite projects and is confident that the materials technologies, capital and maintenance cost issues and commissioning schedule lessons have been fully addressed; reviews of the project by industry third parties and banks since completion of the bankable feasibility study confirm this opinion.

Metallogenic Features and Metalogenic Model of Laterite Gold Deposits in Southern China

Abstract The modern laterite gold deposits in southern China, which belong to reworked laterite deposits, can be further divided into three subclasses and seven types. Their geological features, ore‐forming conditions and regularities are discussed. A geologic‐geochemical metallogenic model for laterite gold deposits has been established.

Fission track dating of ancient man site in Baise, China, and its significances in space research, paleomagnetism and stratigraphy

A large number of artifacts (stone tools) have been discovered in Baise (Bose), Guangxi, China in recent years. They show that ancient man were living in the south of China during very ancient times. During excavation, tektites were discovered in the same layer of deposits as the stone tools. The structure of the layers of deposits in this site was never disturbed, which is the evidence that the stone tools were left behind by the ancient man at the time when the tektites fell on the earth, which were slowly covered over by layers of deposits. Fission track dating has been carried out on tektites. The age of the tektites is 0.732 ± 0.039 Ma, which is also the age of the ancient man in Baise, Guangxi, China. The annealing degree of spontaneous fission tracks in the tektite was investigated by measuring track diameters. A correction of age for track fading has been made by track diameter technique. According to current understanding, tektites were formed by the impact of falling asteroids or comets on the earth's surface. The dating shows that a big impact occurred on the earth 0.732 Ma ago. The coincidence of the age of the tektites with the age of geomagnetic polarity reversal (∼ 0.73 Ma) from the Matuyama Epoch to the Brunhes Epoch proposes a plausible explanation that the possible cause of the geomagnetic polarity reversal is due to the big impact of space objects falling onto the earth. The result of the dating also set up a standard for inferring the ages of the deposits in South China as well as in South-East Asia where laterite (red soil) deposits exist in the entire region.

Impact of nickel mining and metallurgical activities on the distribution of heavy metals in sediments of Levisa, Cabonico and Nipe Bays, Cuba

At MayarO zone, northeast Cuba, important lateritic deposits have been exploited since 1943. The mineral is used as raw material in a nickel-processing plant which discharges its untreated solid and liquid wastes into Levisa Bay. Similarly to the adjacent Nipe and Cabonico bays, fluvial currents from the mining areas convey a significant mineral load into this bay. To assess the environmental impact caused by the mining and the metallurgical activities, the distribution of Ni, Co, Fe, Mn, Cu, Pb and Zn was investigated in surface and core sediment samples. Uni- and multivariate statistical methods as well as different indices and pollutant factors were used to interpret results. These revealed significant environmental impacts in some areas of the three bays with high concentrations of Ni, Co, Fe and Mn, whose values are up to two orders of magnitude greater than the zone baseline levels. The metal concentrations decreased with increasing distance from discharges. A comparison with other Cuban bays and coastal zones, confirmed that the main source of metal pollution in these three bays was not urban and industrial activities, but lateritic mining and metallurgy.

A late Archaean-Palaeoproterozoic (2.6 Ga) palaeosol on ultramafics in the Eastern Transvaal, South Africa

This article describes a palaeosol developed on Archaean (3.4 Ga) ultramafics and overlain by sedimentary rocks of the Chuniespoort Group (2.55 Ga). The palaeosol is thick, mature and complex, forming carapaces on palaeohills. From base to top it comprises four lithological units: (1) carbonated serpentinite; (2) black talc rock; (3) silcrete-dolocrete; (4) silcrete breccia in mudstone matrix. Petrographic and geochemical studies (major elements, plus V, Cr, Ni, Zn, Ga, Y, Zr, Nb, PGE and Th) indicate that units 1 to 3 represent former saprolites and silicified-carbonated saprolites with bedrock textures still preserved. Unit 4 has been more intensely leached, with some admixture of allochthonous sialic material, collapse of the original texture and concentration of the immobile elements. An irregular Ni mineralization in the bottom part of the profiles is described and compared with equivalent modern lateritic deposits. A high carbon content suggests the presence of a surficial mat of primitive micro-organisms which could have contributed to the stability of the palaeosol on the hilly topography and greatly enhanced the weathering rate. The presence of silcrete is indicative of a semi-arid climate, possibly with alternating wet and dry seasons, or of a dry period having succeeded a wet one. The absence of Fe oxides and the general deficiency of this element in the upper part of the profiles, taking into account that the soil was well drained and aerated, support the model of an atmospheric O 2 level much lower than at present by an order of two magnitudes.

Lineaments and tectonic analysis through landsat imagery and its implications on the evaluation of bauxite and laterite deposits in and around Panchpatmali area, Koraput District, Orissa

Lineaments of Panchpatmali plateau and the adjoining areas in Koraput District, Orissa, lying on the East Coast of India, were analysed to elucidate their influence on the occurrence of’ laterite/bauxite duricrust of the area. A detailed lineament map and a map of the explored and expected deposits of laterite and bauxite of the areas have been prepared from satellite imagery after ‘Band Ratioing’ and ‘Maximum Likelihood Classification’ and ground truth study. Development of laterite/bauxite plateaus follows the regional lineament trend of NE - SW, probably due to the tectonic activities in the area. It has been observed that there are atleast two major planation surfaces - the older one shows complete development of laterite/bauxite duricrust, whereas the younger planation surfaces are devoid of any.

The worldwide availability of cobalt

The US Department of Interior, Bureau of Mines has evaluated the potential resource and annual availability of cobalt from 27 deposits or districts in 11 market economy countries. More than 90% of primary cobalt production from market economy countries, mainly by‐product output from copper and nickel operations, was analysed. The producing operations evaluated in this study were expected to produce about 19 000 t of cobalt in 1989, significantly less than the available capacity of 31 000 t. Approximately 1200 000 t of cobalt is potentially recoverable at the demonstrated resource level. Very large additional resources exist, especially in laterite deposits, but are at the inferred level.

The availability of primary nickel from the market economy countries

The US Bureau of Mines has determined the potential availability of nickel from 36 deposits or districts in 16 market economy countries (MECs). More than 95% of production in MECs was analysed. The study indicates the quantity of nickel available in resources and potential annual production at net production costs and on a total cost basis with a 0% and a 10% discounted cash flow rate of return (DCFROR). The properties included in this study contain approximately 33 million tonnes of recoverable nickel. About 26 million tonnes of nickel is potentially recoverable from nickel laterite deposits, of which 4.5 million tonnes can be produced at $2.50/lb or less with a 0% DCFROR. Approximately 7 million tonnes of nickel is potentially recoverable from nickel sulphide deposits of which about 6.3 million tonnes could be produced at $2.50/lb or less at a 0% DCFROR. Sensitivity studies indicate that the total cost of producing nickel from laterite deposits is most sensitive to increases in energy costs, and that the total costs of producing nickel from sulphide deposits is most sensitive to increases in labour costs and by changes in byproduct revenues.

Bauxite deposits in China

Bauxite deposits in China, ranging in age from Late Paleozoic to Cenozoic, are distributed mainly in Shanxi, Shandong Henan, Guizhou, Guangxi and Yunnan. Based on stratigraphic relations they can be classified as 6 types: inter-system marine, inter-system continental, intra-system marine, intra-system continental, weathering lateritic and weathering accumulation types. But in terms of depositional environments, only four types are distinguished, i.e., the marine deposits, continental deposits, lateritic deposits and weathering-accumulation deposits. These deposits have been formed in two steps: firstly, the depression of paraplatform or front basin margins in paleocontinents and secondly, the development of littoral - lagoons on the eroded surface of karstified carbonate bedrocks. The aluminum may have been derived from the carbonate rocks with which the ores are associated, or from adjacent aluminosilicate rocks.

Behaviour of piles in residual and lateritic deposits of Nigeria : Ajayi, L A Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P313–318. Publ Rotterdam: A A Balkema, 1987

Behaviour of piles in residual and lateritic deposits of Nigeria : Ajayi, L A Proc ninth regional conference for Africa on soil mechanics and foundation engineering, Lagos, September 1987V1, P313–318. Publ Rotterdam: A A Balkema, 1987

Relation between chemical composition and particle-size distribution of ores in the profile of nickeliferous laterite deposits of the Rio Tuba Mine, Philippines

Lateritic Ni ore mined in the Rio Tuba Mine, Philippines, derived from ultramafic rock by tropical intense weathering, is generally composed of two accumulated zones, an upper laterite zone and a lower saprolite zone. These two zones are very different in appearance, mineral assemblage, chemical composition, and in other ways. A transitional zone may be seen between the upper and lower zones, but it does not develop to any appreciable thickness. Although serpentine and goethite are still predominant in the constituent minerals, other clay minerals are increasing. The transitional zone may be subdivided into three groups based on chemical composition. The behaviour of the chemical composition in this horizon indicates a complicated process of component transportation under the weathering process. In the ore, chemical components are closely related in particle size of constituent minerals. In the laterite - transitional - saprolite sequence, a common variation range and tendency in chemical composition for each particle size can be seen. However, taking samples with the same particle size the chemical composition obviously differed, representing the characteristics of the components for each zone. Concerning the correlation coefficient of the chemical components of each zone, a somewhat different inter-component relationship can be seen in these zones. These differences of correlation suggest the different complicated lateritized conditions under which they are formed.

A method of exploration for lateritic and bed-rock chromite mineralization used in the Philippines

Prior to 1976, few chromite reserves were known to exist in ultramafic environments with flat to moderate topography, where rock types are concealed below several meters of overlying lateritic soil. It has since been found that those lateritic soils in such environments may contain significant quantities of metallurgical- and chemical-grade chromite ore, recoverable by gravity separation methods. Between 1976 and 1981 several lateritic chromite deposits throughout the Philippines, particularly on Samar Island in the eastern Visayas, were delineated using a method involving auger drilling, test pitting, heavy mineral concentration, and analytical techniques.--Modified journal abstract.

Criteria and problems in estimating global lateritic nickel resources

Although two-thirds of the present nickel production is derived from nickel sulfides, lateritic nickel reserves are estimated to be around three times as large as those of sulfides. This discrepancy is largely caused by the mineralogical complexity of lateritic nickel which precludes low-cost beneficiation by conventional physical methods. Nevertheless, lateritic nickel reserves are bound to become increasingly important because of expected metallurgical advances. Lateritic nickel deposits were formed from peridotitic rocks on peneplaned surfaces during a tropical or subtropical climate. The most important deposits were formed during the Tertiary and the lateritization process still continues in deposits situated in the present tropical or subtropical belts. Other deposits, like those in East Europe and Greece, were formed during much older periods (Palaeogene-Cretaceous). The various types of lateritic nickel deposits, covered or uncovered,in situ or transported, are listed and their characteristics briefly mentioned. Large differences exist in depth, grade, specific gravity, and mineralogical composition—the latter especially in the nickel silicate section as opposed to the overlying limonitic section. These large differences exist even within one individual mining area. Because of the mineralogical complexities and highly irregular boundaries of lateritic nickel deposits (especially the upper and lower boundaries of the nickel silicate section), thorough studies are required to determine the mineralogical composition and ratios of the components. Only then may it be possible to specify with confidence the most suitable metallurgical process which has a strong bearing on the cost and consequently the viability of the deposit. This condition makes the exploitability rating in the McKelvey classification diagram relatively more difficult. Because of the quickly changing geological attributes of deposits even within limited areas, it seems necessary to develop various deposit models for many, if not most, individual metallogenic regions. It does not seens justified or practical to use estimation methodologies based on straight extrapolation. This is especially the case when dealing with the young uncovered type of deposit which constitutes the bulk of global resources. Consequently methodologies no. I (areal value estimation. Cargill, Meyer, Picklyk, Urquidi, 1977) and no. 2 (volumetric estimation) are not considered suitable. It is thought that methodology no. 3 (abundance estimation) in conjunction with no. 5 (Delphi estimation) would work satisfactorily but, as could be expected, the most meaningful results should come from a combination of methodologies nos. 4 (deposit modeling), 5 (Delphi estimation), and 6 (integrated synthesis). A classification of leteritic nickel deposit types is proposed.

Scanning Electron Microscope Study of Bauxites of Different Ages and Origins

AbstractSixty-five bauxite samples of different ages and origins were studied by scanning electron microscopy. Only broken surfaces of the specimens were investigated. Size and form of individual crystals and of grain aggregates were studied as were different types of microtextures and space-fillers.Grain size varies from 0.05 μm to 1 mm. Smallest is the grain size of young karstic bauxite deposits that is explained by a physicochemical retardation effect of the carbonate environment. Significant differences were found by comparing the space-filling of karstic and lateritic bauxite deposits. High-level and low-level lateritic deposits show differences as well.A combined use of macroscopic observations, petrographie microscopy, electron microprobe, SEM, and TЕM furnishes the best clues for any genetic interpretation of bauxites. SEM studies are useful in solving technological problems of bauxite processing.

Nickeliferous Laterite Deposits in Circum-Pacific Region: ABSTRACT

Nickeliferous Laterite Deposits in Circum-Pacific Region: ABSTRACT

Exploration for Bauxite in Sri Lanka, Preliminary Investigations

Abstract Preliminary geochemical investigations for bauxite in Sri Lanka show the existence of laterite deposits containing bauxitic material approaching the lower limit of commercial grade. The geochemical processes responsible have followed two paths resulting in the formation of lateritic bauxite and lateritic iron ore. While the few samples analysed do not give any information regarding the possible reserves of commercial grade bauxite, the existence of economically important bauxitic material, particularly in the Highlands of Sri Lanka has been confirmed.

The Effect of Water Content on the Compressive Strength of Laterized Concrete

Abstract Laterized concrete is defined as concrete in which laterite fines replace sand. A previous paper highlighted only the salient points of difference between laterized and normal concrete. The results reported in this paper are mainly on the effect of water content on the compressive strength of laterized concrete. Other properties such as durability, resistance to frost action, and creep need to be investigated to decide whether or not laterized concrete would be usable in all climates. It is the aim of the author that this paper and his earlier paper will generate research interest in other parts of the world where facilities and climatic conditions are more favorable for the investigations of properties which are not easily investigated in the tropics. The mix design showed that laterized concrete mixes require more water than normal concrete for equal proportions and weights of dry normal concrete and of dry laterized concrete mix. The water/cement ratio recommended for structural laterized concrete mixes of 1:1:2 and 1:1½:3 by weight is 0.65. This water/cement ratio would yield compressive strength of about 23.59 MPa (3425 psi) for 1:1:2 and 21.45 MPa (3110 psi) for 1:1½:3 by weight in 28 days. The water/cement ratio recommended for 1:2:4 mix by weight is 0.75. This would yield about 18.50 MPa (2682 psi) in 28 days. Graphs showing the variation of compressive strength with water/cement ratio and independently with age are presented. A schematic map of the world showing laterite deposits is included. It is suggested that the paper may generate interest in reinforced laterized concrete structural elements and that laterized concrete may eventually be used for structural works in those parts of the world where suitable sharp sand is not available, just as lightweight concrete is now being slowly introduced into major construction works.