Thesis (MEng)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: A desire to increase the efficiency of the comminution process in mineral process systems has led to the need of determining the size distribution of ore particles at various stages in the system. The objective of this research is to investigate the feasibility of the use of an acoustic sensor for measuring particle size distribution. The acoustic signal generated when the particles impact on a cantilever bar is analysed using digital signal processing techniques. As rocks fall onto a metal bar, the bar vibrates. The vibrations contain information th a t is extracted to determine the size of particles tha t impacted on the bar. The bar is modelled as a linear system which is excited by impulses (impact of particles). The response of the bar is deconvolved from the acoustic signal to obtain an impulse whose amplitude is proportional to the energy of the impact. In order to improve size estimates, deconvolution is performed using a statistical model of the impulse sequence (Bernoulli-Gaussian) and then estimated using MAP estimation. Size estimates are not only a function of the mass of particles, but also on the exact position of impact on the bar. Since there is always a variation in the position of impact, size estimates are erroneous. It was found that the position of impact can be determined as to reduce variances dramatically. Due to physical sampling in space, the sensor has a bias towards larger particles. We show how this can be represented mathematically and removed. This project is mainly concerned with rocks in the +8-25mm (+0,7-22 gram) size range. / AFRIKAANSE OPSOMMING: Vergruising van erts in die mineraalbedryf verg groot hoeveelhede energie. Daar is ’n behoefte gei'dentifiseer orn hierdie proses meer effektief te maak. Aangesien die effektiwiteit van ’n meul ’n funksie is van die ertsgroottes wat gemaal word, kan partikel grootte inligting aangewend word om effektiwiteit te bevorder. Die doel van hierdie tesis is om die lewensvatbaarheid van ’n akoestiese sensor vir die doel van partikelgrootte estimasie, te ondersoek. Erts partikels wat val vanaf ’n vervoerband op ’n kantelbalk, veroorsaak dat die balk vibreer. Deur hierdie vibrasies te meet en verwerk, kan inligting aangaande partikel grootte verkry word. Die stelsel word gemodelleer as ’n lineere sisteem met impulse as intree. Die geobserveerde sein is die konvolusie tussen die intree impulse en die impulsweergawe van die sisteem. Deur gebruik te maak van ’n statistiese model en MAP-estimasie, word die effek van die sisteem gedekonvuleer vanaf die geobserveerde sein om ’n benadering van die intree impuls sein te verkry. Die amplitudes van die impulse word gebruik as ’n aanduiding van partikel massa. Partikelgroottes soos benader deur die stelsel, is ’n funksie van die die posisie waar die partikel die balk tref. Deur van patroonherkenning tegnieke gebruik te maak, word die posisie van impak bepaal om sodoende grootte benaderings aan te pas en die variansie van grootte verspreidings te verminder. As gevolg van die feit dat partikels gemonster word deurdat slegs ’n klein persentasie van die hele omvang van partikels ondersoek word, onstaan daar ’n oorhelling ( “bias” ) na groter partikels. Die kans dat groter partikels die balk tref is groter as vir klein partikels. ’n Wiskundige model vir hierdie verskynsel word voorgestel en gewys hoe die die oorhelling geneutraliseer kan word. Hierdie projek het te doen met ertsgroottes +8-25mm (+0,7-22 gram).

Thesis (MScEng)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Metallurgical processes are often high dimensional and non-linear making them difficult to understand, model and control. Whereas the human eye has extensively been used in discerning temporal patterns in historical process data from these processes, the systematic study of such data has only recently come to the forefront. This resulted predominantly from the inadequacy of previously used linear techniques and the computational power required when analysing the non-linear dynamics underlying these systems. Furthermore, owing to the recent progress made with regard to the identification of non-linear systems and the increased availability of computational power, the application of non-linear modelling techniques for the development of neural network models to be used in advanced control systems has become a potential alternative to operator experience. The objective of this study was the development ofa non-linear, dynamic model of an autogenous mill for use in an advanced control system. This was accomplished through system identification, modelling and prediction, and application to control. For system identification, the attractor was reconstructed based on Taken's theorem making use of both the Method Of Delays and singular spectrum analysis. Modelling consisted of the development of multi-layer perceptron neural network, radial basis function neural network, and support vector machine models for the prediction of the power drawn by an autogenous mill. The best model was subsequently selected and validated through its application to control. This was accomplished by means of developing a neurocontroller, which was tested under simulation. Initial inspection of the process data to be modelled indicated that it contained a considerable amount noise. However, using the method of surrogate data, it was found that the time series representing the power drawn by the autogenous mill clearly exhibited deterministic character, making it suitable for predictive modelling. It was subsequently found that, when using the data for attractor reconstruction, a connection existed between the embedding strategy used, the quality of the reconstructed attractor, and the quality of the resulting model. Owing to the high degree of noise in the data it was found that the singular spectrum analysis embeddings resulted in better quality reconstructed attractors that covered a larger part of the state space when compared to the method of delays embeddings; the data embedded using singular spectrum analysis also resulting in the development of better quality models. From a modelling perspective it was found that the multi-layer perceptron neural network models generally performed the best; a multi-layer perceptron neural network model having an appropriately embedded multi-dimensional input space outperforming all the other developed models with regard to free-run prediction success. However, none of the non-linear models performed significantly better than the ARX model with regard to one-step prediction results (based on the R2 statistic); the one-step predictions having a prediction interval of 30 seconds. In general the best model was a multi-layer perceptron neural network model having an input space consisting of the FAG mill power (XI), the FAG mill load (X2), the FAG mill coarse ore feed rate (X3), the FAG mill fine ore feed rate (X4), the FAG mill inlet water flow rate (X7) and the FAG mill discharge flow rates (X9, XIO). Since the accuracy of any neural network model is highly dependent on its training data, a process model diagnostic system was developed to accompany the process model. Linear principal component analysis was used for this purposes and the resulting diagnostic system was successfully used for data validation. One of the models developed during this research was also successfully used for the development of a neurocontroller, proving its possible use in an advanced control system. / AFRIKAANSE OPSOMMING: Metallurgiese prosesse is gewoonlik hoogs dimensioneel en nie-lineêr, wat dit moeilik maak om te verstaan, modelleer, en te beheer. Alhoewel die menslike oog alreeds wyd gebruik word om temporale patrone in historiese proses data te onderskei, het die sistematiese studie van hierdie tipe data eers onlangs na vore gekom. Dit is hoofsaaklik na aanleiding van die onvoldoende resultate wat verkry is deur van voorafgaande lineêre tegnieke gebruik te maak, asook die beperkende berekenings vermoë wat beskikbaar was vir analise van onderliggend nie-lineêre dinamiese stelsels. 'n Verder bydraende faktor is die onlangse vordering wat gemaak is met betrekking tot die identifikasie van nie-lineêre stelsels en die toename in beskikbaarheid van rekenaar-vermoë. Die toepassing van nie-lineêre modellerings tegnieke vir die ontwikkeling van neurale netwerke om gebruik te word in gevorderde beheerstelsels, het 'n potensiële alternatief geword tot operateur ondervinding. Die doelwit van hierdie studie was die ontwikkeling van 'n gevorderde beheerstelsel vir 'n outogene meul gebaseer op 'n nie-lineêre, dinamiese model. Dit is bereik deur middel van stelsel-identifikasie, modellering en voorspelling, en laastens implementering van die beheerstelsel. Vir stelsel-identifikasie is die attraktor van die stelsel bepaal soos gebaseer op Taken se teorema deur gebruik te maak van beide die metode van vertraging en enkelvoudige spektrum analise. Modellering van die stelsel vir die voorspelling van krag-verbruik deur die outogene meul het bestaan uit die ontwikkeling van multilaag-perseptron-neurale netwerke, radiaalbasisfunksie-neurale netwerke, en steunvektor-masjien-modelle. Die beste model is daarna gekies vir validasie deur middel van toepassing vir beheer. Dit is bereik deur 'n neurobeheerder te ontwikkel en te toets deur middel van simulasie. Die aanvanklike inspeksie van proses data wat gebruik sou word vir modellering het egter getoon dat die data 'n aansienlike hoeveelheid geraas bevat. Nietemin, deur die gebruik van 'n surrogaat-data-metode, is dit bevind dat die tyd-reeks wat die krag verbruik van die outogene meul beskryf, duidelik deterministiese karakter toon en dat dit dus wenslik is om 'n nie-lineêre voorspellings-model, soos 'n neurale netwerk te gruik. Gevolglik is gevind dat, wanneer die data vir attraktor hersamestelling gebruik word, 'n verband bestaan tussen die ontvouing-strategie wat gebruik word, die kwaliteit van die gerekonstrueerde attraktor, en die kwaliteit van die daaropvolgende model. As gevolg van die geraas in die data is gevind dat die ontvouing gebaseer op enkelvoudige spektrum analise 'n beter kwaliteit attraktor hersamestelling lewer. So ook is gevind dat 'n groter deel van die toestandruimte gedek word in vergelyking met die metode van vertraging-ontvouing. Deur gebruik te maak van enkelvoudige spektrum-analise, het die dataontvouing ook beter kwaliteit modelle opgelewer. Vanuit 'n modellerings-perspektief is gevind dat die multilaag-perseptron-neurale netwerk-modelle in die algemeen die beste gevaar het. 'n Multilaag-perseptronneurale netwerk met 'n gepaste ontvoude multidimensionele invoer-spasie het die beste gevaar van al die ontwikkelde modelle met betrekking tot vryloopvoorspellings. Geen van die nie-lineêre modelle het egter beduidend (op 'n R2 basis) beter gevaar as die ARX model wanneer daar na die eenstap-voorspellings (oor 'n 30 sekonde interval) gekyk word nie. Die multilaag-perseptron-neurale netwerk met 'n invoer-spasie bestaande uit die meul krag-verbruik (XI), die meullading (X2), die meul growwe-erts voertempo (X3), die meul fyn-erts voertemp ('4), die meul inlaat-water vloeitempo (X7) en die meul uitlaat vloeitempo's (X9, XIO) het in die algemeen die beste gevaar. Aangesien die akkuraatheid van emge neurale netwerk afhanklik is van die data waarmee dit aanvanklik opgestel is, is 'n diagnostiese proses modelontwikkel om die proses-model te vergesel. Lineêre hoofkomponent analise is vir hierdie doel aangewend en die gevolglike diagnostiese stelsel is suksesvol aangewend vir datavalidasie. Een van die modelle ontwikkel gedurende hierdie navorsing is ook suksesvol gebruik vir die ontwikkeling van 'n neurobeheerder wat dien as bewys dat die model goed gebruik kan word in 'n gevorderde beheerstelsel.

[pt] As pelotas de minério de ferro têm suas propriedades fortemente dependentes da natureza das fases escorificadas que se formam durante o processo de queima. Neste trabalho são apresentados os resultados de uma das pesquisas que compõem o projeto cooperativo entre a Samarco e o Grupo de Siderurgia do DEMa / PUC-Rio, envolvendo a possibilidade de utilização de minérios de ferro portadores de fósforo (pellet feed), na produção de pelotas para redução direta. Com este objetivo foram geradas amostras de escórias sintéticas de mesma composição que as das pelotas RD comerciais, as quais foram submetidas a condições experimentais análogas as do processo industrial. Inicialmente a ciclos térmicos em forno tipo pot-grate e, posteriormente, em escala laboratorial, usando forno de mufla, seguido de etapas de resfriamento em velocidades distintas. Foi possível então constatar que velocidades mais altas de resfriamento, aplicadas na etapa final dos ciclos térmicos, produziam escórias sintéticas sensivelmente amorfas, o que levou a conclusão que as fases escorificadas das pelotas RD também se apresentariam como estruturas não cristalinas. Finalmente, por meio de teste especificamente desenvolvido para a análise seletiva de fósforo em fases oxídicas, conseguiu-se obter uma maior eficiencia na mensuração deste elemento quando dissolvido em escórias amorfas, o que viabilizou a medida das quantidades de fósforo que efetivamente migraram para as mesmas, quando se submetiam as amostras de pellet feed a diferentes temperaturas, variados tempos de residencia e distintas basicidades. Por fim, foi possivel concluir ser o incremento de basicidade do pellet feed um fator de significativa melhoria para o transporte e a dissolução do fósforo pelas escórias, em particular quando submetidos a temperaturas superiores a 900 graus Celsius. / [en] Iron ore pellets have their properties strongly dependent on the nature of the phases present in the slags formed during pelletization. In this work are presented the first results of a research program involving the utilization of phosphorous bearing iron ores in the production of DR pellets (Direct Reduction pellets). Aiming at this, synthetic slags, produced with same composition of the gangue of a commercial DR pellet, were submitted to operational conditions similar to those of the industrial pelletizing process, but performed in a pot-grate reactor and in a laboratory furnace. The obtained slags samples were cooled at different rates, permitting to observe that at high cooling rates the slags obtained were amorphous, suggesting the occurrence of a similar amorphous structure for the slags present in the DR pellets. Finally, tests developed for a selective analysis of phosphorous in oxide phases, showed better efficiency when applied to amorphous slags than in crystalline ones. Further, the behavior of the phosphor dissolution in the obtained slags during the heating of pellet feed samples was evaluated. In this phase different temperatures, resident times and basicities were tested using a laboratory furnace. The results indicated improvements in the phosphor dissolution with the basicity increase when temperatures above 900 Celsius degrees were applied.

The significant increase in metal mining and the inevitability of the continuation of this trend suggests that environmental pressures, as well as related impacts, have become an issue of global relevance. Yet the scale of the impact remains, to a large extent, unknown. This paper examines the mining sector's demands on CO2 emissions, water use, as well as demands on land use focusing on four principal metals: iron, aluminium (i.e., bauxite ore), copper, and gold. These materials represent a large proportion of all metallic materials mined in terms of crude tonnage and economic value. This paper examines how the main providers of mining data, the United Nations, government sources of some main metal producing and consuming countries, the scientific literature, and company reports report environmental pressures in these three areas. The authors conclude that, in the global context, the pressure brought about by metal mining is relatively low. The data on this subject are still very limited and there are significant gaps in consistency on criteria such as boundary descriptions, input parameter definitions, and allocation method descriptions as well as a lack of commodity and/or site specific reporting of environmental data at a company level.

A large portion of South west Africa/Namibia is underlain by 2 great orogens. They are the Irumide (Sinclair/Rehoboth) and Damara Orogenies. The L-shaped Irumide Province forms part of a belt which extends over the subcontinent from Namaqualand to as far as Zambia. The volcano-sedimentary sequences of the Irumide are believed to have formed in intracratonic rifts and pull-apart basins during the period 1400 to 900 Ma. The evolution of the NW trending Sinclair Group proceeded by means of 3 major cycles each beginning with the emplacement of basic to intermediate magmas followed by felsic ones. The cycle ended off with subsidence, deposition of immature clastic debris and final tilting of the volcano-clastic sequence. It was suggested that the extensive calc-alkaline lavas present, developed within a magmatic arc above a subduction zone, but this proposal has not been generally accepted. The NE trending Klein Aub-Witvlei Basins consist essentially of red bed alluvial fans and lacustrine sediments with minor volcanics near the base. The red beds and aeolian sediments were deposited in an arid climatic condition. The regional greenschist facies metamorphism and deformation is attributed to a major tectono-thermal event at 1100 Ma. The Damara Orogen (900 - 550 Ma) forms part of the Pan-African mobile belt system of global proportions. The NE trending intracontinental branch (aulacogen) and 2 coastal branches constitute a triple junction with its focal point near Swakopmund. The NE extension of the intracontinental belt has been linked with the Lufilian Arc hosting the renown Zambian Copper Belt deposits. In South West Africa/Namibia this belt hosts many different mineral occurrences which can be grouped into rift and collision related deposits. The tectonic history of the Damara Orogen supports a geodynamic-evolution-with-time hypothesis and represents a transitional phase in which limited Wilson Cycle Tectonics was active. The Theory of Mantle Advection is invoked to explain rifting, thinning and subsidence. Extensive ensialic rifting resulted in a relatively stable Northern Carbonate Platform and several deep troughs hosting turbiditic sequences. Crustal rupture in the Khomas Trough allowed for the emplacement of ocean floor tholeiites known as the Matchless Amphibolite Belt. Subsequent ocean closure and collision resulted in deformation, metamorphism and generation of predominantly S-type granites. The southern continental plate was partially overridden by the northern plate during final collision at 550 Ma. These low angle thrust faults allowed for the emplacement of the Naukluft Nappe Complex on top of younger Nama sediments. The break up of Gondwanaland during the Mesozoic with the splitting of the Atlantic Ocean was responsible for the intrusion of anorogenic alkaline ring complexes along the extension of the NE trending transform faults within the intracontinental branch of the Damara Orogen. A close relationship between the tectonic setting and mineral deposits has been recognized in both the Irumide and Damara Orogenies. In the Irumide, stratiform syngenetic copper deposits are hosted by alluvial fan, playa and lacustrine sediments. The uninterrupted sedimentation from the Irumide to Damara Orogen resulted in similar stratiform copper deposits during the early stages of rifting. In the Damara Orogen the rifting (extensional) phase is characterized by 4 main mineralizing systems: diagenetic/syngenetic (Kupferschiefer-type), epigenetic/hydrothermal Cu-Pb-Zn (Mississippi Valley-type), volcanogenic cupriferous pyrite (Besshi-type) and volcano-exhalative Pb-Zn (Red Sea-type). The collision (compressional) phase was accompanied by 4 main mineralizing processes: epigenetic/hydrothermal Cu-Pb-Zn, hydrotheral/metasomatic Sn-W-rare earth, metamorphogenic Au and U-bearing anatectic melts. The key to the selection of viable exploration targets lies in the understanding of the field evidence and the geodynamics modelling to explain the evolution of the orogen and its associated mineral deposits.

Submitted by Stéfany Moreira (stemellra@yahoo.com.br) on 2013-02-25T18:42:27Z No. of bitstreams: 1 DISSERTAÇÃO_EstudoDepressoresFlotação.pdf: 2366097 bytes, checksum: 9beeb25612b4624e59d30fb2c2743275 (MD5) / Approved for entry into archive by Neide Nativa (neide@sisbin.ufop.br) on 2013-02-27T15:01:23Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO_EstudoDepressoresFlotação.pdf: 2366097 bytes, checksum: 9beeb25612b4624e59d30fb2c2743275 (MD5) / Made available in DSpace on 2013-02-27T15:01:23Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO_EstudoDepressoresFlotação.pdf: 2366097 bytes, checksum: 9beeb25612b4624e59d30fb2c2743275 (MD5) Previous issue date: 2010 / Neste trabalho foram efetuados estudos de depressores na flotação de uma amostra de finos de minério sílico-carbonatado de manganês (estocados como rejeito) da Unidade Morro da Mina / RDM, localizada em Conselheiro Lafaiete-MG. Foram realizados testes de microflotação em tudo de Hallimond modificado, curvas de potencial zeta dos minerais puros na presença e ausência de reagentes e ensaios de flotação em bancada com amostra do resíduo do minério deslamado. Os reagentes estudados foram: fluorsilicato de sódio, metasilicato de sódio, amido de milho, dextrina branca e alguns tipos de quebracho (Floatans T0, T1, T5 e M3) utilizando-se oleato de sódio como coletor. A eficiência dos depressores testados na microflotação em relação à seletividade para a separação do quartzo dos minerais de manganês foi: floatan M3 > floatan T1> fluorsilicato de sódio > metassilicato de sódio > amido de milho > floatan T0 > dextrina > floatan T5. Os pontos isoelétricos dos principais minerais de Mn e ganga presentes neste minério foram determinados: rodonita (pH 2,8), rodocrosita (pH 10,5) e quartzo (pH 1,8). O estudo da adsorção que caracteriza a interação dos reagentes com as superfícies dos minerais mostrou ser de caráter específico. Os depressores mais eficientes na flotação em bancada entre os minerais de Mn e de ganga foram: floatan M3, floatan T1 e fluorsilicato de sódio, onde foram obtidos concentrados com teores de Mn, SiO2 e Al2O3 de aproximadamente 30, 17 e 10 %, respectivamente, para os três depressores testados. No entanto, a recuperação metalúrgica de Mn foi de 72,5 % para o floatan M3, 51 % para o floatan T1 e 45,2 % para o fluorsilicato de sódio. Posteriormente, efetuaram-se estudos preliminares de calcinação desse minério deslamado. O mais alto teor de Mn encontrado foi de aproximadamente 30 % com perda de massa de 11,2 % para temperatura de 1000 °C. ____________________________________________________________________________________________________ / ABSTRACT: Flotation depressants were studied from silicate-carbonate manganese ore samples (waste) at RDM – Morro da Mina, in Conselheiro Lafaiete – MG, Brazil. Micro-flotation tests were conducted in a modified Hallimond cell, also zeta potential curves for pure minerals in the presence or lack of reagents and bench-scale flotation tests for deslimed ore waste sample. The following reagents were studied: sodium fluorosilicate, waterglass, starch, white dextrin, some quebracho kinds (Floatans T0, T1, T5 e M3) and sodium oleate as a collector. The efficiency of the depressants during the micro-flotation regarding the selection for separation of quartzo from manganese mineral was as it follows: floatan M3> floatan T1> sodium fluorosilicate > waterglass > starch > floatan T0 > dextrin > floatan T5. The isolectric points (pl) of the main ore were also determined as rhodonite (pH 2.8), rhodochrosite (pH 10.5) and quartz (pH 1.8). The adsorption test, characterized by the interaction of reagents and mineral surfaces, indicates its specific nature. The most efficient depressants in bench-scale flotation test among Mn ore and ganga were floatan M3, floatan T1 and sodium fluorosilicate containing Mn, SiO2 and Al2O3 concentrations of approximately 30, 17 and 10%, respectively, for all depressants herein mentioned. However, the metallurgical recovery for Mn was 72,5 % when using floatan M3, 51 % for floatan T1 and 45,2% for sodium fluorosilicate. Furthermore, calcination preliminary studies were conducted and the highest concentration of Mn found was approximately 30%, with an 11.2% weight loss for a 1000°C temperature.

O minério de ferro produzido no complexo de Carajás traz consigo características mineralógicas que conferem um elevadíssimo teor de Fe em todas as suas frações granulométricas. Dessa forma, ao final da cadeia produtiva, tanto os produtos comerciais mais grosseiros quanto os finos contem cerca de 62% de Fe contido na sua composição. Importante destacar que em Carajás as fases no processamento desse minério são apenas para cominuição e classificação por tamanho. Não existem etapas de concentração e os produtos são diferenciados por suas respectivas curvas granulométricas: o “granulado” - mais grosseiro (> 13 mm), o “Sinter-Feed” (< 13 mm e > 0,5 mm) e o “pellet feed” (< 0,15 mm). Garantir a correta distribuição granulométrica da matéria prima é uma premissa de mercado. A ultima etapa da classificação é feita através de hidrociclones e gera um overflow ultrafino de altíssima superfície específica maior que 6.500 Blaine e com 45% até 95 % < 7 μm. E ainda possui um elevado teor de Fe - cerca de 62 %. Dessa forma os objetivos gerais dessa pesquisa buscaram a solução para essa oportunidade de recuperar e vender esses rejeitos. O estudo sugeriu através de ensaios com tecnologias capazes de desaguar os ultrafinos gerados para 9,00 % de umidade, que é o valor que permite a movimentação e o manuseio desses rejeitos, além de permitir sua incorporação na blendagem de produtos mais grossos. Desse modo, foram realizados experimentos em diversos laboratórios externos e em escala piloto na Usina de Carajás com amostras dos dois rejeitos ultrafinos das duas fases de hidrociclonagem: o natural e o moído. Ficou evidente que o equipamento tem de combinar necessariamente e de forma eficiente dois fatores essências ao desaguamento: elevadíssimas pressões e altas temperatura na operação desses ultrafinos. A produtividade atingida foi da ordem de 50 t/h x m² para o rejeito da hidrociclonagem do Sinter Feed e 40 t/h x m² para o rejeito dos hidrociclones da Moagem. / The Iron ore that is produced in Carajás mining complex brings mineralogical characteristics that give a very high Fe content in all its size fractions. Thus, at the end of the production chain both coarser and fine contains about 62% Fe contained in its composition. Importantly, in Carajás stages in the processing of this ore are for reduction and classification by size. There is thus no concentration steps and products are differentiated by their respective size distribution curves: the "grain" - coarser (> 13 mm), the "Sinter-Feed" (<13 mm and > 0.5 mm) and the "pellet feed" (<0.15 mm). Ensure proper particle size distribution of the raw material is a market premise. The last step of classification is made using hydrocyclones and generates an overflow ultrafine high specific surface area greater than 6.500 Blaine and with 45% to 95% <7 μm. And has a high Fe content - about 62%. The overall objectives of this research sought the solution to this opportunity to recover and sell these “tailings”. The study suggested by testing with technologies capable of flowing into the ultrathin generated to 9.00% of moisture, which is the value that allows movement and handling these wastes, and allows their incorporation into the blending of thicker products. Thus, experiments were carried out in several external laboratories and pilot-scale plant in the Carajás with samples of both ultrafine “tailings” of the two phases of hydrocycloning: the natural and the ground. It was evident that the equipment must necessarily match and two efficiently factors essences to dewatering: very high pressure and high temperature operation of these “tailings”. The productivity achieved was around 50 t/h x m² in reject of the Sinter Feed hydrocycloning and 40 t/h x m² to reject of the grinding hydrocyclones.

A região de estudo localiza-se na porção da Bacia do Camaquã, sendo classicamente conhecida com “Janela Bom Jardim”. Esta área já foi intensamente estudada, principalmente em decorrência dos depósitos minerais amplamente distribuídos. Apesar disso ainda não existe um consenso com relação à evolução tectônica da região, desde processos formadores da bacia até eventos pósdeposicionais, como também com relação ao seu posicionamento estratigráfico dentro da sequência deposicional da Bacia do Camaquã. Dessa forma, este trabalho vem contribuir e acrescentar aos modelos anteriores com dados geocronológicos e termocronológicos, aplicados diretamente às rochas sedimentares da região, bem como, novos dados de estrutural. Para tanto, submetemos seis amostras de rochas sedimentares da região de Minas do Camaquã à análise pelo método U-Pb com LA-ICP-MS e SHRIMP, aplicado a zircões detríticos, no intuito de mapear possíveis áreas fonte dos sedimentos como também, propor uma idade máxima de deposição para a sequência. Estas mesmas amostras foram utilizadas para separação de apatitas para análise termocronológicas (traços de fissão em apatitas), com o objetivo de caracterizar eventos de soerguimento e denudação relacionados à tectônica que afetou a área. O estudo de proveniência possibilitou identificar uma grande contribuição de zircões de idade Brasiliana, principalmente do final do Neoproterozóico e secundariamente populações de zircões de idade Paleoproterozóica, principalmente relacionadas ao Ciclo Transamazônico. A população principal foi correlacionada às intrusões graníticas do Terreno Taquarembó, e possivelmente contribuições do Batólito Pelotas, como também, das sequências vulcano-sedimentares mais antigas da própria Bacia do Camaquã. As idades Paleoproterozóicas foram atribuídas á rochas do Complexo Granulítico Santa Maria Chico e Complexo Encantadas, como também, zircões retrabalhados das rochas metassedimentares do Complexo Metamórfico Porongos. Ainda foi possível estimarmos a idade máxima de deposição da sequência em 554 Ma a partir do grão de zircão mais jovem datado posicionando estas rochas dentro do intervalo deposicional do Grupo Santa Bárbara. A análise por traços de fissão em apatitas permitiu identificar quatro populações de idades principais. Estas populações foram atribuídas à influência de dois eventos orogênicos na margem sul – ocidental do Gondwana: Famatiniana e Gondwanides. O primeiro evento é bem documentado pelas populações de 407-362 Ma e o segundo pelas populações de 302 Ma e 242-211 Ma. A quarta população (133 Ma) foi registrada em uma única amostra indicando um evento térmico ocasionado por intrusões vulcânicas associadas ao vulcanismo Paraná-Etendeka (Cretáceo inferior). Por fim, dados estruturais permitiram identificar uma evolução tectônica complexa, marcada por processos relacionados formação da bacia até reativações pósdeposicionais. Os eventos D1 e D2 foram associados a esforços gerados durante os estágios finais do Ciclo Brasiliano, com campos de tensão S10E-N10W e SE-NW, respectivamente. Um evento D3 com campo de tensão W-L registra reativações causadas pela Orogenia Famatiniana. O evento D4 marcado por uma compressão NNE-SSW e uma extensão NE-SW são relacionados aos processos tectônicos Triássicos (Orogenia Gondwanides). Um último evento D5 extensional (L-W) foi correlacionado aos processos de separação do Gondwana. / The study area is located in the southern portion of the Camaquã Basin, being classically known as "Bom Jardim Window". This area has been intensely studied, mainly due to the ore deposits widely distributed. Yet there is still no consensus regarding the tectonic evolution of the region, since basin inception processes until postdepositional events, but also regarding its stratigraphic position within the depositional sequence Basin Camaquã. Thus, this work contributes to previous models with geochronological and thermochronological data, applied directly to the sedimentary rocks of the region, as well as new structural data. Therefore, we submitted six samples of sedimentary rocks from the Camaquã Mines region to U-Pb method with LA-ICP-MS e SHRIMP applied to detrital zircons in order to map possible source areas of the sediments, as well as, proposing a maximum depositional age for the sequence. These same samples were used for apatite separation for thermochronological analysis (apatite fission tracks), with the aim of characterizing uplift and denudation events related to tectonics process that affected the area. Provenance study enabled us to identify a large contribution of Brasiliano zircon ages, especially from Late-Neoproterozoic and secondarily, zircons populations of Paleoproterozoic age, mainly related to Trans-Amazonian Cycle. The main population was correlated with granitic intrusions from Taquarembó Terrene and possibly contributions from Pelotas Batholith, as well as, from older volcano-sedimentary sequences of the Camaquã Basin. Paleoproterozoic ages were assigned to rocks of Santa Maria Chico Granulitic Complex and Encantadas Complex, as well as, reworked zircons from metasedimentary rocks of Porongos Metamorphic Complex. Still it was possible to estimate the maximum deposition age of the sequence on 554 Ma from the youngest zircon grain dated. Previous isotopic data allow positioning these rocks within the depositional range of Santa Bárbara Group. Apatite fission track analysis identified four main ages populations. These populations were attributed to the influence of two orogenic events on the Southwestern margin of Gondwana: Famatinian and Gondwanides. The first event is well documented by the 407-362 Ma age populations and the second by the 302 Ma and 242-211 Ma. The fourth population (133 Ma) was recorded in only one sample indicating a thermal event caused by volcanic intrusions associated with volcanism Paraná-Etendeka (Lower Cretaceous). Finally, structural data allowed identifying a complex tectonic evolution, characterized by basin inception processes until post-depositional reactivations. The events D1 and D2 were associated with stresses generated during the final stages of the Brazilian Cycle with stress fields of S10E-SE-NW and SE-NW, respectively. A third event (D3) with W-L stress field records the reactivation Famatinian Orogeny. The D4 event marked by a NNE-SSW compression and a NE-SW extension related to Triassic tectonic processes (Gondwanides Orogeny). One last extensional (W-L) event (D5) was correlated to the processes of separation of Gondwana.

Em uma operação mineira, a quantidade e a qualidade do minério disponível para alimentação na usina são essenciais para a continuidade e flexibilidade das operações. A quantidade de minério liberado não é considerada em softwares especialistas de sequenciamento de lavra. Geralmente quando o minério liberado é utilizado em rotinas de planejamento, a tonelagem mínima de minério liberado é definida a partir de métodos empíricos. Este estudo desenvolve uma metodologia que auxilia na definição da quantidade de minério liberado a ser considerada nos planos de lavra. Por meio da análise de um estudo de caso, usando krigagem ordinária como método de estimativa e simulação geoestatística para acesso à incerteza, foi avaliado o potencial da metodologia proposta. Foram gerados planos de lavra de cinco anos como referência a partir de cada um dos dois modelos de blocos. Os sequenciamentos de referência foram usados para gerar novos sequenciamentos, com quantidades variáveis de minério liberado (a saber, um, três, cinco e oito meses) para homogeneização na lavra, com posterior alimentação de usina com pilhas de homogeneização. Usando estas possíveis configurações, observou-se o impacto no valor presente líquido de cada um dos cenários e os efeitos do uso de minério liberado na variação de teores para composição de pilhas de homogeneização. A convergência desses critérios é capaz de fornecer diretrizes para a definição da quantidade adequada de minério liberado, a ser usada nos planos de lavra, que permita um balanço entre despesas com antecipação de descobertura para liberação de minério e, também, propicie uma atenuação da variância de teores na formação de pilhas de homogeneização para alimentação da usina. / In a mining operation the quantity and quality of the exposed ore available for plant feeding are essential for the continuity and flexibility of the operations. The quantity of exposed ore it is not considered in the mine sequencing specialist softwares. Generally when esposed ore is considered in mine planning routines, the minimum tonnage of exposed ore is defined by empirical methods. This study develops a methodology that helps in the definition of the quantity of exposed ore to be considered in the mine planning. Trough analyzing a case study, using ordinary kriging and geoestatistical simulation to access the uncertainty, it was evaluated the proposed methodology potential. It was generated five year mine planning as a reference for each one of the two block models. The reference mine plans were used to generate new scenarios with variable quantities of exposed ore (namely one, three, five and eight months) to mining blend, with posterior plant feed with homogenization piles. Using these possible configurations, it was observed the impact on the net present value of each scenario and the effects of using exposed ore on the grade variability while composing homogenization piles. The convergence of these criteria is able to give drivers for the definition of the quantity of exposed ore, to be used in the mine plans, which balances the expenses with stripping anticipation for ore exposure and give lower grade variability in the homogenization pile formation for plant feed.

O presente trabalho teve como objetivo avaliar as interações entre bolhas com distintos tamanhos (diâmetros) e partículas minerais e o efeito de combinações destas bolhas na flotação de minérios, em escala de bancada. As bolhas empregadas nesses estudos foram: i) Nanobolhas – NBs, diâmetro médio de 150 – 200 nm; ii) Microbolhas – MBs, diâmetro médio de 70 μm; e iii) Macrobolhas – MaBs, diâmetro médio de 1 mm. As dispersões de NBs e MBs foram geradas a partir da despressurização de água saturada com ar e cavitação hidrodinâmica em válvula agulha. As pressões de saturação foram, respectivamente, 2,5 e 4,0 bar. Os estudos de interação bolhas-partícula mineral foram desenvolvidos utilizando um sistema fotográfico que permitiu avaliar a adesão de bolhas às partículas de quartzo (grão de alta pureza) e apatita em função do tipo de bolhas injetadas. Os resultados mostraram que a maior adesão de bolhas no grão de apatita ocorreu com a combinação de NBs + MBs + MaBs e, no caso do quartzo, uma expressiva concentração de MaBs aderidas foi obtida após “condicionamento” do mineral com NBs. As NBs ficaram confinadas às superfícies dos grãos minerais devido à dissipação da energia livre superficial dos sólidos em função de sua rugosidade e, desta forma, aumentaram o mecanismo de adesão de outras bolhas (MBs e/ou MaBs). O estudo de avaliação das associações de bolhas na flotação foi realizado com os sistemas minerais quartzo e minério fosfático. No caso do minério fosfático, constituído por 35% de partículas finas (< 37 μm), os estudos avaliaram a combinação de i) NBs + MaBs; ii) MBs + MaBs; e iii) NBs + MBs + MaBs, nos parâmetros cinéticos e de separação na flotação, em relação ao ensaio standard, que emprega o uso de apenas MaBs. Os efeitos foram avaliados em quatro situações que compreenderam variação de porcentagem de sólidos (28 e 35% em peso) e concentração de reagentes (1000 g.t-1 de coletor + 600 g.t-1 de depressor; e 500 g.t-1 de coletor + 300 g.t-1 de depressor; sendo que o coletor de apatita empregado foi óleo de soja saponificado com hidróxido de sódio e o depressor das partículas de ganga - magnetita, carbonatos, micas, quartzo, diopsídio e perovskita/anatásio - foi amido de milho gelatinizado com hidróxido de sódio). O emprego combinado de bolhas apresentou incrementos na recuperação de P2O5, com pequena queda no teor de P2O5 e elevada cinética, em relação aos ensaios STD em praticamente todas as condições estudadas, com valores variando entre 0,2 e 8.9%. Os incrementos quando a porcentagem de sólidos foi de 35% p/p (até 2,7%) foram consideravelmente menores que os obtidos com 28% de sólidos (até 8,9%). Em algumas condições, o uso concomitante de MBs + MaBs e NBs + MBs + MaBs foi capaz de superar, já na primeira coleta (1,5 min de ensaio), a recuperação total de fosfato obtida no ensaio standard. No caso do quartzo, os ensaios de microflotação (realizados em tubo de Hallimond modificado) com e sem a presença de NBs mostraram que a associação de NBs às MaBs aumentou a recuperação de quartzo (até 39%) em praticamente todas as condições estudadas, mostrando sua efetividade tanto com partículas finas quanto com as mais grossas. Já os ensaios realizados em célula mecânica com e sem adição de NBs, mostraram que o emprego de NBs foi responsável pelo aumento de 23 pontos percentuais na recuperação de quartzo. Ainda, a cinética de flotação aumentou significativamente e já no primeiro min do ensaio com NBs obteve-se cerca do dobro da recuperação de quartzo do ensaio standard. Os resultados obtidos na dissertação mostram o elevado potencial das NBs combinadas a outras distribuições de tamanhos de bolhas na melhoria do processo de adesão bolha-partícula e na flotação de minérios fosfáticos finos e de frações granulométricas distintas de quartzo, principalmente em tempos curtos. / The objective of this work was to evaluate the interactions between bubbles with different sizes (diameters) and mineral particles and the effect of the combinations of these bubbles on the flotation of ores, on a bench scale. The bubbles used in these studies were: i) Nanobubbles - NBs, mean diameter of 150-200 nm; ii) Microbubbles - MBs, average diameter of 70 μm; and iii) Macrobubbles - MaBs, average diameter of 1 mm. Dispersions of NBs and MBs were generated after depressurizing-cavitation of the saturated water in air. The saturation pressures were, respectively, 2.5 and 4.0 bar. The bubble-particle mineral interaction studies were developed using a photographic system that allowed to evaluate the adhesion of bubbles to the particles of quartz (high purity grain) and apatite according to the type of bubbles injected. The results showed that the highest adhesion of bubbles in the apatite grain occurred with the combination of NBs + MBs + MaBs and, in the case of quartz, an expressive concentration of adhered MaBs was obtained after "conditioning" of the mineral with NBs. The NBs were confined to the surfaces of the mineral grains as a result of the dissipation of the free surface energy of the solids due to their roughness and, therefore, it increased the adhesion mechanism of other bubbles (MBs and / or MaBs). The study of the evaluation of the associations of bubbles in the flotation was carried out with the mineral systems quartz and phosphate ore. In the case of phosphate ore, consisting of 35% fine particles (<37 μm), the studies evaluated the combination of i) NBs + MaBs; ii) MBs + MaBs; and iii) NBs + MBs + MaBs, in the kinetics and flotation separation parameters, in relation to the standard test, which employs the use of only MaBs. The effects were evaluated in four situations involving percentage of solids (28 and 35% by weight) and concentration of reagents (1000 g·t-1 collector + 600 g·t-1 depressant and 500 g·t-1 collector + 300 g·t-1 of depressor; the apatite collector used was a saponified soybean oil with sodium hydroxide and the depressant of the ganga - magnetite, carbonates, micas, quartz, diopside and perovskite / anatase particles - was a gelatinized corn starch with sodium hydroxide). The combined use of bubbles presented increases in the recovery of P2O5, with a small drop in P2O5 content and high kinetics, in relation to the STD tests in practically all the studied conditions, with values varying between 0.2 and 8.9%. The increments when the percentage of solids was 35% w/w (up to 2.7%) were considerably lower than those obtained with 28% solids (up to 8.9%). In some conditions, the concomitant use of MBs + MaBs and NBs + MBs + MaBs was able to overcome, in the first min and a half of the test, the total phosphate recovery obtained in the standard tests. Regarding the quartz, the microflotation tests (performed in modified Hallimond tube) with and without the presence of NBs showed that the association of NBs with MaBs increased the recovery of quartz (up to 39%) in practically all the studied conditions, showing its effectiveness with both fine and coarse particles. However, the tests performed in mechanical cell with and without addition of NBs showed that the use of NBs was responsible for the increase of 23 percentage points in quartz recovery. Also, flotation kinetics increased significantly and ealier in the first min of the NBs test, about twice the quartz recovery of the standard test was achieved. The results obtained in the dissertation show the high potential of NBs combined with other bubble size distributions in the improvement of the bubble-particle adhesion process and the flotation of fine phosphatic or quartz granulometric fractions, especially in short times.