Neste trabalho apresenta-se um estudo comparativo de sistemas de classificações geotécnicas aplicadas aos solos tropicais. Para 38 solos do interior paulista foram realizados ensaios de classificação/identificação pelo método das pastilhas segundo os procedimentos de Nogami e Villibor (1994b) e Godoy e Bernucci (2002) e ensaios de azul de metileno (Fabbri, 1994). Além disso, foram executados ensaios de permeabilidade buscando-se relações entre esta variável e o comportamento (laterítico/não laterítico) dos solos e suas características físicas. Também foram analisados resultados de ensaios de sucção na umidade ótima, obtidos por Takeda (2005). Inicialmente foram analisados resultados dos ensaios de difração de raios-X, microscopia eletrônica de varredura e da classificação MCT, todos obtidos por Takeda (2005), onde foi constatada uma coincidência entre a gênese dos solos e seu comportamento (laterítico/ não laterítico). A partir desta constatação, foram confrontados os resultados obtidos através do método das pastilhas, segundo os dois procedimentos destacados acima, e dos ensaio de azul de metileno com a classificação MCT. Nesta etapa, foi verificada uma concordância de 81,6% entre o método das pastilhas de Nogami e Villibor (1994b) e a MCT. Os resultados dos ensaios de azul de metileno (Fabbri, 1994) concordaram com a MCT em 92,1%. Com relação ao método das pastilhas de Godoy e Bernucci (2002), observou-se que este procedimento necessita de revisões. Os coeficientes de permeabilidade não revelaram uma relação clara com o comportamento laterítico ou não laterítico dos materiais. Também não foi observada uma relação entre este coeficiente e características físicas dos solos, quando tomadas isoladamente. Os valores de sucção mostraram que os solos com maiores teores de argila apresentam maiores valores de sucção. Também se observou que para iguais teores de argila, solos de comportamento laterítico apresentaram sucções menores que os solos de comportamento não laterítico. / This work presents a comparative study of different tropical soils geotechnical classification systems. Classification/identification tests of tablet method as proposed by Nogami and Villibor (1994b) and Godoy and Bernucci (2002) and methylene blue adsorption tests (Fabbri, 1994) were done for 38 soil samples of São Paulo state countryside, in Brazil. Futhermone, hydraulic conductivity tests were performed in intent of search relations between this variable and the soil behavior (lateritic/non lateritic), and its physical characteristics. Suctions results (Takeda, 2005) on optimum water content, also were analyzed . Initially XRD and SEM test\'s results, and MCT classification\'s results, obtained from Takeda (2005), were analyzed, where a coincidence between soil genesis and its behavior (lateritic/non lateritic) was observed. At this point, the methylene blue adsorption test and tablet method\'s results were compared with the ones obtained from MCT classification. At this time, tablet method as proposed by Nogami and Villibor (1994b) and MCT classification presented a 81.6% of agreement rate. Methylene blue adsorption showed a agreement rate of 92.1% with the MCT classification. The tablet method proposed by Godoy and Bernucci (2002) seemed to need some revision. The hydraulic conductivity values didn\'t show any clear relationship with the soil\'s lateritic/non lateritic behavior. A relation between the hydraulic conductivity and the physical characteristics wasn\'t observed, when these last ones was correlated, one by one, with the hydraulic conductivity. The suction values showed that the most clay content leads to higher suctions values. Lateritic soils with the same clay content showed lower suctions values then non lateritic soils with the same clay content.

<p>The complex nature and composition of regolith cover in Southern Africa is a major challenge to geochemical mapping for concealed mineralization. Some of the setbacks to successful geochemical exploration may be ascribed to the use of various partial extraction techniques,without a profound understanding of the regolith components and their composition. This investigation therefore focuses on the use of hydroxylamine partial extraction geochemistry for geochemical mapping in regolith over two contrasting environments viz / aeolian sand-calcrete regolith over Au mineralization at Amalia Blue Dot Mine in South Africa and lateritic regolith covering the Ni-Cu deposit at Kabanga Main and Luhuma in Tanzania. Regolith samples from the above areas were sieved and extracted with hydroxylamine hydrochloride solution and analyzed for multi-element by AAS and ICP-MS techniques. A stepwise optimization of the hydroxylamine extraction technique of samples from both areas was carried out and incorporated into the analytical programme (in a pilot study). Results of hydroxylamine partial extraction generally gave better anomaly contrast and reflection of bedrock mineralization than the conventional aqua regia techniques that were previously used in the region. The results however show that lateritic regolith may be best extracted using 0.25M hydroxylamine while 0.1M concentration appears most suitable for extraction of aeolian-calcrete regolith. The above results are corroborated by principal component analysis of the analytical data that show various element associations, e.g. with Fe-Mn oxides while others possibly belong to the loosely adsorbed or exchangeable group. The&nbsp / gochemical maps in the pilot study areas at Amalia, Kabanga and Luhuma show elevated element contents or clusters of anomalies of diverse elements associated with Fe-Mn oxides. Geochemical mapping at Kabanga with deeply concealed mineralization however shows variability of subdued element patterns over mineralized areas. Geochemical signatures associated with hydroxylamine hydrochloride partial leach are therefore characterized by a lower geochemical background than that using conventional aqua regia leach. This study leads recommending for further investigations into partial extraction of the exchangeable group of elements, possibly using ammonium acetate.</p>

<p>The complex nature and composition of regolith cover in Southern Africa is a major challenge to geochemical mapping for concealed mineralization. Some of the setbacks to successful geochemical exploration may be ascribed to the use of various partial extraction techniques,without a profound understanding of the regolith components and their composition. This investigation therefore focuses on the use of hydroxylamine partial extraction geochemistry for geochemical mapping in regolith over two contrasting environments viz / aeolian sand-calcrete regolith over Au mineralization at Amalia Blue Dot Mine in South Africa and lateritic regolith covering the Ni-Cu deposit at Kabanga Main and Luhuma in Tanzania. Regolith samples from the above areas were sieved and extracted with hydroxylamine hydrochloride solution and analyzed for multi-element by AAS and ICP-MS techniques. A stepwise optimization of the hydroxylamine extraction technique of samples from both areas was carried out and incorporated into the analytical programme (in a pilot study). Results of hydroxylamine partial extraction generally gave better anomaly contrast and reflection of bedrock mineralization than the conventional aqua regia techniques that were previously used in the region. The results however show that lateritic regolith may be best extracted using 0.25M hydroxylamine while 0.1M concentration appears most suitable for extraction of aeolian-calcrete regolith. The above results are corroborated by principal component analysis of the analytical data that show various element associations, e.g. with Fe-Mn oxides while others possibly belong to the loosely adsorbed or exchangeable group. The&nbsp / gochemical maps in the pilot study areas at Amalia, Kabanga and Luhuma show elevated element contents or clusters of anomalies of diverse elements associated with Fe-Mn oxides. Geochemical mapping at Kabanga with deeply concealed mineralization however shows variability of subdued element patterns over mineralized areas. Geochemical signatures associated with hydroxylamine hydrochloride partial leach are therefore characterized by a lower geochemical background than that using conventional aqua regia leach. This study leads recommending for further investigations into partial extraction of the exchangeable group of elements, possibly using ammonium acetate.</p>

Neste trabalho apresenta-se um estudo comparativo de sistemas de classificações geotécnicas aplicadas aos solos tropicais. Para 38 solos do interior paulista foram realizados ensaios de classificação/identificação pelo método das pastilhas segundo os procedimentos de Nogami e Villibor (1994b) e Godoy e Bernucci (2002) e ensaios de azul de metileno (Fabbri, 1994). Além disso, foram executados ensaios de permeabilidade buscando-se relações entre esta variável e o comportamento (laterítico/não laterítico) dos solos e suas características físicas. Também foram analisados resultados de ensaios de sucção na umidade ótima, obtidos por Takeda (2005). Inicialmente foram analisados resultados dos ensaios de difração de raios-X, microscopia eletrônica de varredura e da classificação MCT, todos obtidos por Takeda (2005), onde foi constatada uma coincidência entre a gênese dos solos e seu comportamento (laterítico/ não laterítico). A partir desta constatação, foram confrontados os resultados obtidos através do método das pastilhas, segundo os dois procedimentos destacados acima, e dos ensaio de azul de metileno com a classificação MCT. Nesta etapa, foi verificada uma concordância de 81,6% entre o método das pastilhas de Nogami e Villibor (1994b) e a MCT. Os resultados dos ensaios de azul de metileno (Fabbri, 1994) concordaram com a MCT em 92,1%. Com relação ao método das pastilhas de Godoy e Bernucci (2002), observou-se que este procedimento necessita de revisões. Os coeficientes de permeabilidade não revelaram uma relação clara com o comportamento laterítico ou não laterítico dos materiais. Também não foi observada uma relação entre este coeficiente e características físicas dos solos, quando tomadas isoladamente. Os valores de sucção mostraram que os solos com maiores teores de argila apresentam maiores valores de sucção. Também se observou que para iguais teores de argila, solos de comportamento laterítico apresentaram sucções menores que os solos de comportamento não laterítico. / This work presents a comparative study of different tropical soils geotechnical classification systems. Classification/identification tests of tablet method as proposed by Nogami and Villibor (1994b) and Godoy and Bernucci (2002) and methylene blue adsorption tests (Fabbri, 1994) were done for 38 soil samples of São Paulo state countryside, in Brazil. Futhermone, hydraulic conductivity tests were performed in intent of search relations between this variable and the soil behavior (lateritic/non lateritic), and its physical characteristics. Suctions results (Takeda, 2005) on optimum water content, also were analyzed . Initially XRD and SEM test\'s results, and MCT classification\'s results, obtained from Takeda (2005), were analyzed, where a coincidence between soil genesis and its behavior (lateritic/non lateritic) was observed. At this point, the methylene blue adsorption test and tablet method\'s results were compared with the ones obtained from MCT classification. At this time, tablet method as proposed by Nogami and Villibor (1994b) and MCT classification presented a 81.6% of agreement rate. Methylene blue adsorption showed a agreement rate of 92.1% with the MCT classification. The tablet method proposed by Godoy and Bernucci (2002) seemed to need some revision. The hydraulic conductivity values didn\'t show any clear relationship with the soil\'s lateritic/non lateritic behavior. A relation between the hydraulic conductivity and the physical characteristics wasn\'t observed, when these last ones was correlated, one by one, with the hydraulic conductivity. The suction values showed that the most clay content leads to higher suctions values. Lateritic soils with the same clay content showed lower suctions values then non lateritic soils with the same clay content.

Magister Scientiae - MSc / The complex nature and composition of regolith cover in Southern Africa is a major challenge to geochemical mapping for concealed mineralization. Some of the setbacks to successful geochemical exploration may be ascribed to the use of various partial extraction techniques,without a profound understanding of the regolith components and their composition. This investigation therefore focuses on the use of hydroxylamine partial extraction geochemistry for geochemical mapping in regolith over two contrasting environments viz; aeolian sand-calcrete regolith over Au mineralization at Amalia Blue Dot Mine in South Africa and lateritic regolith covering the Ni-Cu deposit at Kabanga Main and Luhuma in Tanzania. Regolith samples from the above areas were sieved and extracted with hydroxylamine hydrochloride solution and analyzed for multi-element by AAS and ICP-MS techniques. A stepwise optimization of the hydroxylamine extraction technique of samples from both areas was carried out and incorporated into the analytical programme (in a pilot study). Results of hydroxylamine partial extraction generally gave better anomaly contrast and reflection of bedrock mineralization than the conventional aqua regia techniques that were previously used in the region. The results however show that lateritic regolith may be best extracted using 0.25M hydroxylamine while 0.1M concentration appears most suitable for extraction of aeolian-calcrete regolith. The above results are corroborated by principal component analysis of the analytical data that show various element associations, e.g. with Fe-Mn oxides while others possibly belong to the loosely adsorbed or exchangeable group. The gochemical maps in the pilot study areas at Amalia, Kabanga and Luhuma show elevated element contents or clusters of anomalies of diverse elements associated with Fe-Mn oxides. Geochemical mapping at Kabanga with deeply concealed mineralization however shows variability of subdued element patterns over mineralized areas. Geochemical signatures associated with hydroxylamine hydrochloride partial leach are therefore characterized by a lower geochemical background than that using conventional aqua regia leach. This study leads recommending for further investigations into partial extraction of the exchangeable group of elements, possibly using ammonium acetate. / South Africa

Lateritic soils which have been described as highly weathered tropical or sub-tropical residual soils with varying proportions of particle sizes ranging from clay size to gravel, were studied in an attempt to establish its suitability or otherwise as sustainable material in building bricks and housing developments that will meet the present challenge of sustaining the environment without costing too much and maintaining a high standard of strength, durability and aesthetics. Index properties of the lateritic soils tested revealed them as mostly well-graded, comprising both cohesive (silt and clay) and cohesionless (sand and gravel) soil fraction. The mineralogical analysis shows the presence of sesquioxides in the clay portion which were found to be very useful in the natural binding process as well as in the presence of a stabiliser (cement). The geotechnical analysis on the lateritic soil revealed a strong compressive strength with a relatively sound dry density which could guarantee a good durability in resulting bricks made from these soil materials. Further test on the strength and durability of compressed earth bricks (CEBs) made from these lateritic soils revealed a brick with compressive strength ranging between 6.33 and 15.57 MPa which are considered to be of very good strength coupled with its sound durability strength established over a period more than one year under different kinds of severe weather and seasonal conditions. In conclusion, sesquioxides presence and mineralogy of lateritic soils were found to be largely responsible for their good compressive and durability strength which made them good and sustainable materials for CEBs. / Thesis (PhD)--University of Pretoria, 2017. / Geology / PhD / Unrestricted

Este trabalho apresenta diversas considerações a respeito do dimensionamento de pavimentos de baixo custo que utilizam solos lateríticos em sua estrutura. Esses pavimentos são construídos para rodovias de baixo volume de tráfego que, apesar de serem utilizadas por pequeno número de veículos diariamente, podem ser solicitadas por veículos muito pesados, provenientes das regiões agrícolas, usineiras e industriais. A despeito dos solos lateríticos não atenderem as especificações tradicionais e das estruturas serem incompatíveis com as normas de dimensionamento vigentes, as soluções de baixo custo têm mostrado um bom desempenho em rodovias de baixo volume de tráfego. Foram estudadas diversas variáveis intervenientes no projeto do pavimento: a composição do tráfego nessas rodovias; o clima atuante no Estado de São Paulo, responsável por umidades de equilíbrio inferiores aquelas nas quais os solos foram compactados; e as propriedades geotécnicas dos solos lateríticos. Foram enfocadas as características desses solos que auxiliam na sua identificação em campo e em laboratório, e que podem ser exploradas para o bom desempenho dos pavimentos. A partir de ensaios de módulos de resiliência, mostra-se a importância da coesão dos solos lateríticos, responsável por sua estabilidade e comportamento adequado em bases de pavimentos. Finalmente, são verificadas as estruturas de pavimentos de baixo custo com base nos conceitos do método norte-americano de dimensionamento de pavimentos de AASHTO-1986. Os resultados corroboram o uso de estruturas esbeltas, normalmente adotadas no Estado de São Paulo. / This thesis proposes to study several aspects of the design of low-cost pavements structurally consisting of lateritic soils. These pavement are utilized for low-volume roads; although used on a daily basis by a small number of vehicles, they might also be requested by heavy trucks typical for agricultural and industrial areas. Thin-layered pavements of lateritic soils have been successfully used in low-volume roads in the State of São Paulo, is spite of the fact that these soils do not conform to traditional specifications and that such structures are not in accordance to current design requirements. Several factors relevant to the pavement design have been analyzed: traffic composition on such roads; climatic conditions of the state of São Paulo, responsible for equilibrium moisture contents lower than those at which the soils were originally compacted; and the geotechnical properties of lateritic soils. Emphasis is given to soil characteristic useful to field and laboratory identification and necessary to ensure good performance of the pavement. The importance of the cohesion of lateritic soils, responsible for the stability and good performance of pavement bases, is demonstrated by means of resilient moduli test results. Finally, the structure of low-cost pavements has been verified within the framework of the AASHTO-1986 pavement design method, The results support the use of thin-layered pavement structures, widely adopted in the State of São Paulo.

Em virtude das várias aplicações do cobre, acredita-se que a demanda por esse metal irá aumentar nos próximos anos, e consequentemente, o seu preço. Dessa forma, as mineradoras enfrentam o desafio de aprimorar e aperfeiçoar os processos produtivos a fim de atender sua futura demanda. Frações de cobre podem ser encontradas no licor de lixiviação do minério limonítico de níquel e a troca iônica com adsorvente sólido é uma das tecnologias disponíveis para promover a sua recuperação e o seu reaproveitamento. O presente trabalho teve como objetivo estudar o processo de adsorção dos íons de cobre presente em um licor sintético baseado no licor de lixiviação atmosférica do minério limonítico de níquel através de um sistema de resina de troca iônica utilizando a resina quelante Dowex XUS43605. A viabilidade da técnica escolhida foi analisada em função da influência de parâmetros por meio de ensaios em batelada e coluna de leito fixo utilizando uma solução sintética. O tempo de contato, o pH, a massa de resina e a temperatura foram avaliados. A resina quelante Dowex XUS43605 mostrou-se mais seletiva para o cobre em pH igual a 1,5, tendo sido definido esse pH como o de trabalho. Verificou-se que 1g é uma dosagem suficiente para recuperar o cobre da solução em escala laboratorial considerando 50mL de solução sintética. O incremento na temperatura não alterou a adsorção do cobre pela resina, sendo determinado que a temperatura de trabalho esteja entre 25-35°C. O modelo de isotermas de adsorção de Langmuir apresentou melhor ajuste entre a resina e o cobre do que os modelos de Freundlich e de Temkin. O modelo cinético pseudosegunda-ordem descreveu o processo de adsorção considerando a quimiossorção como a etapa limitante. Os ensaios em coluna de leito fixo possibilitaram a produção de uma solução com concentração reduzida de Cu2+ em 93% na etapa de carregamento. Pela etapa de eluição com ácido sulfúrico (H2SO4) 1mol/L, obteve-se uma solução 10 vezes mais concentrada em Cu2+ com relação à solução sintética. A solução resultante da etapa de eluição seguiu para os ensaios de precipitação, a qual permitiu a separação do cobre dos íons metálicos pela ação do agente precipitante CaCO3 e a geração de um precipitado composto por três fases: brochantite [Cu4SO4(OH)6], posnjatike [Cu4SO4(OH)6.H2O] e gesso (CaSO4.2H2O). / Considering the various applications of copper, it is believed that the demand for copper will increase in the coming years and, consequently, its price. Hence, the mining companies face the challenge of improving the productive processes to supply their future demand. Copper fractions can be found in liquor leaching nickel limonite ore and ion exchange with solid adsorbent is one of the available technologies which promote its recovery and reuse. The present work was aimed at studying the adsorption process of copper ions present in a synthetic liquor based on the atmospheric leaching liquor of the nickel limonite ore through an ion exchange resin system using Dowex XUS43605 chelating resin. The feasibility of the chosen technique was analyzed in relation to the influence of parameters by means of batch and fixed bed tests using a synthetic solution. The contact time, pH, amount of resin and temperature were evaluated. Dowex XUS43605 chelating resin showed to be more selective for copper at pH 1.5, and this pH was defined as the working pH. It has been found that 1g is a sufficient dosage to recover copper from the solution on a laboratory scale considering 50mL of synthetic solution. The increase in temperature did not change the adsorption of the copper by the resin, and it was determined that the working temperature is between 25-35°C. The Langmuir adsorption isotherms model showed a better fit between resin and copper than the Freundlich and Temkin models. The pseudosecond-order describes the sorption process and it indicates that the rate-limiting step is chemisorption. The fixed bed column tests allowed the production of a solution with reduced concentration of Cu2+ in 93% the loading step. By the elution step with 1mol/L of sulfuric acid (H2SO4), a solution 10 times more concentrated in Cu2+ was obtained in relation to the synthetic solution. The solution from the elution step followed to the precipitation tests, which allowed the separation of copper from the metal ions by the action of the precipitating agent CaCO3 and the generation of a precipitate composed of three phases: brochantite [Cu4SO4(OH)6], posnjatike [CuSO4(OH)6.H2O] and gypsum (CaSO4.2H2O).

In this study, an attempt has been made to hydrometallurgical extraction of cobalt and nickel by atmospheric pressure sulphuric acid leaching and a pug-roast-leach process using two stage roasting for lateritic ore. The ore used in the study was obtained from &Ccedil / aldag Lateritic Ore, Manisa, Turkey. The metal contents of the ore are 2.1 % Ni, 0.12 % Co, 32.45 % Fe, 1.01 % Mn, 2.58 % Cr, 0.78 % Mg and 1.01 % Al. The reserve of lateritic ore deposit is approximately 40 million tonnes. In the study, first sulphuric acid leaching was applied at atmospheric pressure for leaching the &Ccedil / aldag lateritic ore. The effect of various parameters, such as leaching time, leaching temperature, particle size, pulp density and acid strength on Ni and Co extractions were determined. By leaching at 80oC for 40 wt % H2SO4 addition of ore, 1/3 pulp density, Ni and Co extractions were found 44.49 % and 53.03 % respectively, yielded a pregnant solution containing 3.11 g/L Ni and 0.12 g/L Co. But the result of atmospheric pressure sulphuric acid leaching was considered insufficient from the recovery point of view. In the pug-roast-leach process, which is consisted of a two stage roasting followed by water leaching, decomposition temperature differences of sulphates of cobalt, nickel and iron are exploited. In this process, amount of acid, sulphatization and decomposition temperature, sulphatization and decomposition time, leaching temperature and time, solid/liquid ratio, and the effect of water addition during pugging were optimized. Under the optimized conditions (sulphuric acid: 25 wt % of ore / moisture: 20 wt % of ore / sulphatization temperature: 450oC / sulphatization time: 30 minutes / decomposition temperature: 700oC / decomposition time: 60 minutes / leaching temperature: 70oC / leaching time: 30 minutes and solid-liquid ratio: 1/4 by weight), Co and Ni extractions were found 91.4 and 84.4 percent, respectively. A pregnant solution containing 3.084 g/L Ni and 0.185 g/L Co was obtained. These results were considered sufficient for the leaching of lateritic nickel ores.

[pt] Este trabalho apresenta um estudo do comportamento mecânico, em especial nas características de resistência, de um solo laterítico submetido à contaminação de licores cáusticos a diferentes concentrações. O programa experimental envolveu ensaios de caracterização, ensaios químicos, difração de raios-X, microscopia eletrônica de varredura e ensaios triaxiais com diferentes valores de concentrações cáusticas. Propriedades mecânicas foram determinadas mediante a execução de ensaios triaxiais CID a diferentes concentrações cáusticas, assim como as interações físico- químicas que foram determinadas mediante ensaios químicos de pH, capacidade de troca catiônica e ataque sulfúrico. Os resultados do programa experimental demonstraram uma acentuada variação de volume do solo, a qual está ligada à presença dos licores cáusticos e, por outro lado, também indicaram que os parâmetros de resistência ao cisalhamento do solo são pouco afetados pelos licores cáusticos. / [en] This work presents the results of a laboratory study on the effects of infiltration of a caustic liqueur on the stress- strain- strength behavior of a sandy lateritic soil. The experimental program consisted of general characterization,chemicals tests, X-ray diffraction analysis, electron microscopy and triaxial tests using the caustic liqueur at different concentrations.Mechanic and hydraulic properties were obtained performing triaxial CID tests with different caustic concentrations. Physical- chemical interactions were evaluated through of determination of pH, cation exchange capacity and sulfuric attack tests. The results obtained showed that soil suffers large volume changes under percolation of the liqueur, with these changes being a function of the caustic concentration, on the other hand, the shear strength parameters are little affected by the liqueur.