In this study, the implementation of membrane technology at Anglo Platinum’s base metals refinery to separate acid from metal containing solutions was investigated. The refinery includes a circuit known as the “sulphur removal section”, where the acid in the spent nickel electrolyte is neutralized with caustic soda to remove the excess sulphur from the overall process. Reagent costs associated with acid neutralisation, result in high operating expenditures. An alternative process route is required to improve efficiencies and stay competitive. Nanofiltration was investigated to separate acid from nickel, with the aim of recovering the acid and thereby reducing the need for expensive neutralisation. The objectives of this study were twofold: (1) investigate and simulate the current base metals refinery, and (2) use the understanding and process know-how to investigate the use of nanofiltration by modifying the simulation to include for this technology. The modified process simulation was then used to evaluate the type of membrane required for technical viability. The process investigation of the refinery proceeded with literature studies done on base metals recovery process, chemical reactions and design criteria applicable to the process. A simulation of the base metals refinery was undertaken in Aspen Plus using the information established in the process investigation. The simulation provided insight into the operational issues across the flowsheet, and identified key areas of the process which were sensitive to parameter changes in the sulphur removal section. Areas which were impacted were the electrowinning and copper removal section. The simulation therefore provided a useful tool to predict process variabilities as a result of plant modifications. The investigation into nanofiltration found that it can successfully be used to separate metal ions from acid, subject to the constraints of metal ion concentrations. Pre-treatment of the nickel spent electrolyte was required to remove most of the sodium sulphate in solution, since this can cause fouling and thereby degrade membrane performance. For this reason, a cold crystallization process was introduced for the removal of sodium sulphate. However the sodium removal process caused the sodium sulphate levels in the electrowinning feed to drop below 100 g/l. Therefore minor modifications had to be made to the electrowinning pre-treatment process. The nanofiltration process itself consisted of a series of six nanofiltration stages with dilution of the interstage feed to allow the system to operate below osmotic pressure and wash out all the acid from the system. The modified simulation including the new sulphur removal circuit (nanofiltration process) was completed by integrating the current base metals refinery simulation with the new sulphur removal process, thereby providing a tool where different membrane characteristics could be varied to enable the performance of the overall process to be evaluated. The membrane parameters varied were the nickel rejection, the sodium rejection and the acid rejection. The simulation predicted that each of the cases which varied the mentioned parameters would be technically feasible, although not necessarily economically feasible. The process was most sensitive to acid rejection. The key variables were the amount of water used for dilution, and the membrane size. An exponential distribution was present for the sensitivity of membrane size versus acid rejection; thus realistic membrane sizes can only be achieved if the acid rejection is -100% or less. Furthermore, the addition of dilution water results in the nickel being washed out with the acid, despite nickel rejection being in the region of 99.5%. This demonstrates the importance of the membrane nickel rejection to be as high as possible. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

In this study, the implementation of membrane technology at Anglo Platinum’s base metals refinery to separate acid from metal containing solutions was investigated. The refinery includes a circuit known as the “sulphur removal section”, where the acid in the spent nickel electrolyte is neutralized with caustic soda to remove the excess sulphur from the overall process. Reagent costs associated with acid neutralisation, result in high operating expenditures. An alternative process route is required to improve efficiencies and stay competitive. Nanofiltration was investigated to separate acid from nickel, with the aim of recovering the acid and thereby reducing the need for expensive neutralisation. The objectives of this study were twofold: (1) investigate and simulate the current base metals refinery, and (2) use the understanding and process know-how to investigate the use of nanofiltration by modifying the simulation to include for this technology. The modified process simulation was then used to evaluate the type of membrane required for technical viability. The process investigation of the refinery proceeded with literature studies done on base metals recovery process, chemical reactions and design criteria applicable to the process. A simulation of the base metals refinery was undertaken in Aspen Plus using the information established in the process investigation. The simulation provided insight into the operational issues across the flowsheet, and identified key areas of the process which were sensitive to parameter changes in the sulphur removal section. Areas which were impacted were the electrowinning and copper removal section. The simulation therefore provided a useful tool to predict process variabilities as a result of plant modifications. The investigation into nanofiltration found that it can successfully be used to separate metal ions from acid, subject to the constraints of metal ion concentrations. Pre-treatment of the nickel spent electrolyte was required to remove most of the sodium sulphate in solution, since this can cause fouling and thereby degrade membrane performance. For this reason, a cold crystallization process was introduced for the removal of sodium sulphate. However the sodium removal process caused the sodium sulphate levels in the electrowinning feed to drop below 100 g/l. Therefore minor modifications had to be made to the electrowinning pre-treatment process. The nanofiltration process itself consisted of a series of six nanofiltration stages with dilution of the interstage feed to allow the system to operate below osmotic pressure and wash out all the acid from the system. The modified simulation including the new sulphur removal circuit (nanofiltration process) was completed by integrating the current base metals refinery simulation with the new sulphur removal process, thereby providing a tool where different membrane characteristics could be varied to enable the performance of the overall process to be evaluated. The membrane parameters varied were the nickel rejection, the sodium rejection and the acid rejection. The simulation predicted that each of the cases which varied the mentioned parameters would be technically feasible, although not necessarily economically feasible. The process was most sensitive to acid rejection. The key variables were the amount of water used for dilution, and the membrane size. An exponential distribution was present for the sensitivity of membrane size versus acid rejection; thus realistic membrane sizes can only be achieved if the acid rejection is -100% or less. Furthermore, the addition of dilution water results in the nickel being washed out with the acid, despite nickel rejection being in the region of 99.5%. This demonstrates the importance of the membrane nickel rejection to be as high as possible. / MIng (Chemical Engineering), North-West University, Potchefstroom Campus, 2014

This thesis involves the design and development of reagents for the recovery of base metals (specifically zinc, nickel and cobalt) in hydrometallurgical solvent extraction processes. The work aims to demonstrate how ligand design can affectively tune the strength and selectivity of extractants to achieve efficient recovery of the desired base metals. Chapter 1 reviews current solvent extraction processes used in extractive metallurgy, encompassing both the well established technologies developed for sulfate streams as well as those more recently explored for treating chloride streams. Also reviewed, is the nature of the chemical binding involved in the three key modes of extraction; namely cation transport, anion transport and metal salt transport. Chapter 2 summarises the methodologies that have been established during this research for the appropriate testing of these reagents. Chapter 3 deals exclusively with the processing of zinc sulfide ores with an aim to design reagents to achieve concentration and separation of zinc in chloride hydrometallurgical circuits. The amido functionalised reagents that are reported have a common structural feature with ligands that have been previously studied by the Tasker group (Ross J. Ellis Thesis, University of Edinburgh, 2009). A six membered chelate ring is formed by a protonated amino nitrogen atom and an amido oxygen atom in a sequence of the type R2HN+-CH2-NR-CO-R. This differs from those previously studied which have a sequence of the type R2HN+-CH2-CHR-CO-NR2. The pro-ligands (L) operate via an anion exchange mechanism (Equation 1) whereby two protonated ligands (LH+) coordinate to the outersphere of anionic zinc(II) or iron(III) chloridometalates from acid chloride solutions using both N-H and C-H hydrogen-bond donors. pH dependent solvent extraction experiments have concluded that this reagent series achieves zinc(II) loading with pH0.5 values that are competitive with the previous ligand series (Ross J. Ellis Thesis, University of Edinburgh, 2009). Chloride concentration dependent solvent extraction experiments have demonstrated that the reagents show an unusually good selectivity for ZnCl4 2- over chloride or FeCl4 - in equilibrium of the type; yLorg + yH+ +MClx y- ⇌ [(LH)yMClx](org) (1) The development of bidentate and tridentate pyrazolone-based pro-ligands for the extraction of nickel and cobalt from mixed metal sulfate streams is considered in Chapters 4 and 5. These reagents (LH) operate via metal cation transport, where an inner-sphere complex of nickel(II) or cobalt(II) is formed with the ligand (L-) see Equation 2. A combination of N, O and S donors has been incorporated into 1-phenyl-3-methyl-4- acylpyrazol-5-ones and their respective 4-acylpyrazolone oximes in order to tune the bidentate ligands (L-) for optimal coordination with nickel(II) or cobalt(II). Substituent effects have also been investigated, by synthesising a series of 1-(2-X-phenyl)-3-methyl-4- acylpyrazol-5-one oximes [X = Cl, H]. Substitution in the 3-position of the phenol group in phenolic oximes has been reported to increase extractant strength for copper by two orders of magnitude (Ross S. Forgan Thesis, University of Edinburgh, 2008). Similar improvements were not observed in this study. The nature of this effect has been attributed to buttressing of hydrogen-bonds, where the substituent forms a stabilising, bifurcated hydrogen-bond between the oximic hydrogen and the pyrazolonic oxygen. yLHorg + My+ ⇌ [(L)yM]org + yH+ (2) Tridentate analogues of the oxime reagents above have been prepared as imines derived from anilines contained o-O, S or N donor atoms. It was hoped that these would give high spin octahedral nickel(II) complexes in extraction processes. They proved to be weak extractants. Chapter 6 focuses of the development of bidentate pyrazolethiones for the selective extraction of cobalt from manganese in acidic sulfate streams. These reagents have been designed to favour coordination to metals in a tetrahedral geometry as shown by L. Emeleus and A. Smith for copper and zinc (Lucy Emeleus Thesis, University of Edinburgh 1999 and Andrew Smith Thesis, University of Edinburgh 2000).

Student Number : 0006342N - PhD thesis - School of Chemistry - Faculty of Science / An improved slurry method for determination of PGMs, gold and base metals (Ni, Cu, Fe and Co) using ICP-OES analytical instrument has been developed. This method has been successfully applied to quantitate metals in mineral concentrates and biological samples (grass, lichens, leaves and tree trunks) and validated using analytical figure of merit that include limits of detection, limits of quantition, accuracy and precision. Sample grinding using Fritsch GmbH Pulverissette Planetary Mono Mill was optimized to get > 60% and >80% of the particles to < 5.0 μm and < 10 μm respectively. The optimum grinding conditions for a sample mass of 0.4 g was determined as 130 rpm grinding speed and 30 minutes grinding time. An additional 15 minutes mixing with reagent was employed to ensure better slurry homogeneity for improved precisions. Five slurry dispersants; tetrasodium pyrophosphate, Triton X-100, dodecylbenzene sulfonic acid sodium salt, potassium cyanide and potassium thiocyanate, were evaluated at varied concentrations and 0.1% v/v Triton X-100 established as the best dispersant for slurry preparation. The ICP-OES sample delivery system was modified by introducing an extension elbow between the torch and the spray chamber that not only effectively reduced the sample residence time in the plasma for efficient atomization of the particles but also acted as a gravitational sieve eliminating larger particles and droplets. Prepared slurries were continuously agitated using an ultrasonic bath prior to and during aspiration into ICP-OES to prevent sedimentation and ensure constant stability of the slurry. Optimum operating conditions for ICP-OES established as 1600 W and 1450 W plasma power for PGMs and base metals respectively, using a nebulizer flow rate of 0.8 mL min-1, coolant gas flow rate of 13.0 mL min-1, auxiliary gas flow rate of 1.0 L min-1 with a sample uptake rate of 0.2 mL min-1. Limits of detection for the developed technique were determined in μg g-1 as 0.075, 0.039, 0.115, 0.071, 0.035 and 0.118 for Au, Ir, Pd, Pt, Rh and Ru respectively and 0.15, 0.391, 0.345 and 0.217 for Ni, Cu, Fe and Co respectively. Limits of quantitation in μg g-1 were obtained as 0.250, 0.130, 0.383, 0.237, 0.117 and 0.393 for Ir, Pd, Pt, Rh and Ru respectively and 0.5, 1.31, 1.15 and 0.723 for Ni, Cu, Fe and Co respectively. Good accuracy was recorded for all the base metals as well as for the platinum group metals and gold except iridium that was susceptible to copper interference. Two measurements of precision, reproducibility and repeatability were assessed. Reproducibility was obtained in percentages as 12, 7.93, 5.54, 10 and 12 for Au, Pd, Pt, Rh and Ru respectively and 9.9, 10, 9.8 and 10 for Ni, Cu, Fe and Co respectively. Repeatability was obtained in percentages as 11, 7.03, 4.94, 8.08 and 9.85 for Au, Pd, Pt, Rh and Ru respectively and 9.4, 9.6, 9.7 and 10 for Ni, Cu, Fe and Co respectively. Good percentage recoveries were obtained of 104.3%, 98.3%, 98%, 90.5% and 92.8% for Au, Pd, Pt, Rh and Ru respectively. Percentage recoveries of 109%, 111%, 89.9% and 100% for Ni, Cu, Fe and Co respectively were obtained. The simplicity and low cost of sample preparation used in this method enables it to be easily adopted in any ICP-OES laboratory. A single analyst may achieve more sample through-puts than before per day (including re-grinding and analysis), resulting in a highly economical and rapid technique for determination of metals.

The base metal distribution in, and losses to, Anglo Platinum six-in-line and slag cleaning furnace slags were characterised to coincide with various process changes at Waterval Smelter from 1999 to 2009. The base metals are presumed to be reliable indicators of PGE losses and are easier to detect and measure than these elements are. In addition, base metal and sulphur levels are used to monitor and control many smelter processes, including slag cleaning and converting. Some losses to slag are recoverable but others are not – these have been quantified during this study. Slag composition and smelting temperatures have varied substantially, and optimisation of the slag cleaning furnace – a first for the South African platinum industry – has produced a wide variation in oxidation conditions. Most of the base metal losses in the slag cleaning furnace are mechanically entrained matte particles, the largest of which should be recovered. These have been examined to establish any relationship between composition, size, and depth within the furnace so that recommendations can be made to limit these types of losses. In the six-in-line furnaces, over half of base metal losses to slag are as dissolved phases, which are not recoverable. Levels of dissolved metals have been measured and related to furnace operating conditions and slag composition. The prediction of such base metal losses is not easy, because the slag compositions are so complex. One aspect of the project has been to compare the measured distribution of the base metals with those calculated using the FactSage equilibrium model, to identify problem areas, and to recommend actions which could improve the predictions of this and similar modelling programs for base metal dissolution in slag. New electron microbeam techniques have been developed to quantify base metal distribution in slag, and novel combinations of these techniques with analytical chemistry and Mössbauer Spectroscopy have been pioneered. / Dissertation (MSc)--University of Pretoria, 2009. / Materials Science and Metallurgical Engineering / unrestricted

<p> S^32/S^34 ratios have been determined between some coexisting sulfides from the Heath Steele B-1 orebody and five other stratiform deposits in the Bathurst-Newcastle area, New Brunswick, and in crushed ore samples and pyrites from three across deposit profiles in the B-1 orebody. Zn, Cu, Pb and Ag abundances have been established across the orebody. Fractionations of S^32/S^34 ratios between coexisting sulfides have been determined in heating experiments at temperatures of 350 to 500°C and isotope effects measured in aqueous precipitation and exchange experiments at 25°C. S^32/S^34 fractionations between given coexisting sulfides from all the sulfide deposits are found to show only small variations. Isotope exchange is generally rapid in dry sulfide systems. Metal sulfides in aqueous solutions are slightly enriched in S^32 relative to the H2S with which they precipitate or communicate. It is concluded that the sulfide deposits have been regionally metamorphosed. The origins that have been proposed for the deposits so far are discussed and a model is suggested to explain the sulfur isotope and base metal abundances in the B-1 orebody.</p> / Thesis / Doctor of Philosophy (PhD)

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The main purpose of the base metal refinery (BMR) as operated by Lonmin at their Western Platinum Ltd BMR, is to remove base metals – such as copper and nickel – from a platinum group metal (PGM) containing matte. The leaching processes in which this is done pose several challenges to the control of the process. The most significant of these is the slow dynamics of the process, due to large process units, as well as the continuously changing composition of the first stage leach residue, which is not measured on-line. This is aggravated by the fact that the exact leaching kinetics (and therefore the effect of the disturbances) are not understood well fundamentally. The slow process dynamics mean that controllers cannot be tuned aggressively, resulting in slow control action. The large residence times and off-line composition analyses of major controlled variables also mean that the effects of operator set point changes are visible only the following day, often by a different shift of operators. Dorfling (2012) recently developed a fundamental dynamic model of the pressure leach process at Lonmin‟s BMR. This dynamic model incorporates 21 chemical reactions, as well as mass and energy balances, into a system of 217 differential equations. The model provides a simulation framework within which improved control strategies can be investigated. The primary aims of this study are twofold. The first is to validate the model for the purpose of the investigation and development of control structure improvements. This is done by comparing the model to plant data, and adapting it if necessary. The second aim to reconsider the current control philosophy to the extent that is allowed by the model‟s determined validity. The current plant control philosophy aims to maintain a PGM grade of 65%, while the copper in the solids products of the second and third leaching stages should be below 25% and 3.5% by mass, respectively. Two areas of particular concern in this process that have been raised by Lonmin are the control of the temperature of the first compartment and the addition of pure sulphuric acid to control the acid concentration in the second stage leach. Dynamic plant data were used to calibrate the model, which was migrated from its received MATLAB platform to Simulink, to assist with control development. Flow rates were imported from the data, with some data values adapted for this purpose, due to mass balance inconsistencies. The outputs from the calibrated model were compared with corresponding data values. The model was found to be suitable for the investigation and development of the control structures of pressure, temperatures and inventories (termed basic regulatory control) and the acid concentration and solids fraction in the preparation tanks (termed compositional regulatory control). It was, however, found to be inadequate for the investigation and development of supervisory control, since it does not provide accurate compositional results. The leaching of copper is especially under-predicted, with the predicted copper concentration in the second stage product being approximately 46% lower than data values. The basic and compositional regulatory control structures were investigated. For each of these a base case was developed which aimed to represent the relevant current control structure, assuming optimal tuning. The variable pairings for the basic regulatory control were reconsidered using a method proposed by Luyben and Luyben (1997), since this part of the process does not permit the generation of a relative gain array (RGA) for variable pairing. The resulting pairing corresponds with Lonmin‟s current practice. Considering the temperature control of compartment 1, it was found that the addition of feed-forward control to the feedback control of the level of the flash tank improves the temperature control. More specifically, during an evaluation where the temperature‟s set point is varied up to 1%, the IAE of the temperature of compartment 1 was decreased with 7.5% from the base case, without disturbing the flash tank. The addition of feed-forward control allows for more rapid control and more aggressive tuning of this temperature, removing the current limit on ratio between the flash recycle stream and the autoclave feed. The compositional control was investigated for the second stage leach only, due to insufficient flow rate and compositional information around the third stage preparation tank. Variable pairing showed that three additive streams are available for the preparation tanks of the second and third stage leach to control the acid concentration and solids fraction in those tanks. Focussing on the second stage, the aim was to determine whether the acid concentration in the flash tank can be successfully controlled without the addition of pure acid to the tank. With four streams available around the second stage preparation tank to control its mass/level, the acid concentration and solids fraction, three manipulated variables were derived from these streams. The resulting pairings were affirmed by an RGA. Control loops for the control of acid concentration and solids fraction in the flash tank were added as cascade controllers, using the preparation tank‟s control as secondary loops. The added compositional control was evaluated in two tests. The first of these entailed the adding of typical disturbances, being the flash recycle rate, the solids and water in the feed to the second stage preparation tank and the acid concentration in copper spent electrolyte. In the second test the control system was tested for tracking an acid concentration set point. It was found that the cascade structure controls the acid concentration in the flash tank less tightly than the base case (with an IAE that is 124% and 80.6% higher for the two tests), but that it decreases the variation of solids fraction (lowering the IAE with 40.8% with the first test) in the same tank and of the temperature in the first compartment (lowering the IAE with 73.6% in the second test). It is recommended that the relative effects of these three variables on leaching behaviour should be investigated with an improved model that is proven to accurately predict leaching reactions in the autoclave. / AFRIKAANSE OPSOMMING: Die hoofdoel van die basismetaal-raffinadery (BMR), soos dit bestuur word deur Lonmin by hulle Western Platinum Ltd BMR, is om basismetale – soos koper en nikkel – te verwyder uit 'n mat wat platinum groep metale (PGM) bevat. Die logingsprosesse waarin dit gedoen word hou talle uitdagings in vir die beheer van die proses. Die mees beduidende hiervan is die proses se stadige dinamika, wat veroorsaak word deur groot proseseenhede, sowel as die deurlopend veranderende samestelling van die eerste stadium residue (wat nie aanlyn gemeet word nie). Dit word vererger deur die feit dat die presiese logingskinetika (en daarom ook die effek van versteurings) nie fundamenteel goed verstaan word nie. Die stadige dinamika beteken dat die beheerders die aggressief verstel kan word nie, en dit lei tot stadige beheeraksies. Die groot verblyftye en aflyn samestellingsanalises van die belangrikste beheerde veranderlikes beteken dat die gevolge van 'n operateur se stelpunt veranderinge slegs die volgende dag sigbaar is – dikwels in die skof van 'n ander operateur. Dorfling (2012) het onlangs 'n fundamentele, dinamiese model van die drukloog proses by Lonmin se BMR ontwikkel. Hierdie dinamiese model inkorporeer 21 chemiese reaksies, sowel as massa- en energiebalanse, in ‟n stelsel van 217 differensiaalvergelykings. Die model bied 'n simulasie-raamwerk waarbinne verbeterde beheerstrategieë ondersoek kan word. Die hoofdoel van hierdie studie is tweeledig. Die eerste hiervan is om die model te valideer vir die ondersoek en ontwikkelling van beheerstruktuur verbeteringe. Dit is gedoen deur die model met aanlegdata te vergelyk en dit aan te pas, indien nodig. Die tweede doel is om die huidige beheerfilosofie te heroorweeg tot op 'n punt wat toegelaat word deur die bepaalde geldigheid van die model. Die huidige beheerfilosofie van die aanleg mik om 'n gehalte van 65% te handhaaf, terwyl die koper in die vastestof produk van die tweede en derde logingsstadia onderskeidelik onder 25% en 3.5% op 'n massa basis moet wees. Twee probleem-areas, soos ge-opper deur Lonmin, is die beheer van die temperatuur in die eerste kompartement en die byvoeging van suiwer swaelsuur om die suurkonsentrasie van die tweede stadium te beheer. Dinamiese aanlegdata is gebruik om die model te kalibreer. Hierdie model is van die oorspronklike MATLAB platform na Simulink gemigreer, ten einde beheerontwikkelling te vergemaklik. Vloeitempo's is van die data af ingevoer na die model toe, met sekere data waardes wat aangepas is vanweë massabalans inkonsekwenthede. Die uitsette van die gekalibreerde model is met die ooreenstemmende data waardes vergelyk. Daar is bevind dat die model geskik is vir die ondersoek en ontwikkelling van die beheer van druk, temperature en tenks (basiese reguleringsbeheer), sowel as die beheer van suurkonsentrasies en vastestoffraksies in die bereidingstenks (reguleringsbeheer van die samestelling). Daar is egter bevind dat die model nie geskik is vir die ondersoek en ontwikkelling van toesigbeheer nie, aangesien dit nie akkurate samestellingsresultate genereer nie. Die voorspelde loging van koper is veral te laag, met die model wat koperkonsentrasies vir die tweede stadium voorspel wat ongeveer 46% laer is as ooreenstemmende data waardes. Die basiese en samestelling reguleringsbeheer strukture is ondersoek. Vir elkeen is ‟n basisgeval ontwikkel wat poog om die huidige beheerstruktuur te verteenwoordig, met optimale verstellings aanvaar. Die paring van veranderlikes vir die basiese reguleringsbeheer is heroorweeg met deur middel van ‟n metode wat deur Luyben en Luyben (1997) voorgestel is, aangesien hierdie deel van die proses nie die opstel van ‟n relatiewe winsmatriks (RWM) vir die paring toelaat nie. Die uiteindelike paring stem ooreen met Lonmin se huidige praktyk. Met die heroorweging van die temperatuurbeheer van kompartement 1 is daar bevind that die byvoeging van vooruitvoer beheer by die terugvoerbeheer van die flitstenk die temperatuurbeheer verbeter. Meer spesifiek het die IAE van hierdie temperatuur met 7.5% verlaag van die basisgeval af nadat die temperatuur se stelpunt tot met 1% gevariëer is – sonder om die flitstenk te versteur. Die byvoeging van vooruitvoer beheer laat vinniger beheer en meer aggressiewe verstellings van die temperatuur toe, aangesien die huidige beperking op die verhouding tussen die flitsstroom en die outoklaaf voer verwyder word. Die samestellingsbeheer is slegs ondersoek in die geval van die tweede loogstadium as gevolg van onvoldoende vloeitempo- en samestellingsinligting om die bereidingstenk van die derde stadium. Die paring van veranderlikes het gewys dat drie voerstrome onderskeidelik beskikbaar is vir beide die bereidingstenks van die tweede en derde stadia, om die suurkonsenstrasies en vastestoffraksies in hierdie tenks te beheer. Met die fokus op die tweede stadium was die doel om te bepaal of die suurkonsentrasie in die flitstenk suksesvol beheer kan word sonder dat suiwer suur by hierdie tenk gevoeg word. Met vier strome beskikbaar rondom die bereidingstenk van die tweede stadium om die massa/vlak, die suurkonsentrasie en die vastestoffraksie te beheer, is drie manipuleerde veranderlikes vanuit hierdie strome afgelei. Die uiteindelike paring is bevestig deur 'n RWM. Beheerlusse is ingevoeg vir die beheer van die suurkonsentrasie en vastestoffraksie in die flitstenk, met die bereidingstenk se beheer wat dien as sekondêre lusse in kaskadebeheer. Die kaskadebeheer is geëvalueer in twee toetse. Die eerste hiervan behels die invoer van tipiese versteurings, soos die vloeitempo van die flitsstroom, die vastestof en water in die voer na die tweede stadium se bereidingstenk en die suurkonsentrasie in die gebruikte elektroliet. In die tweede toets is die vermoë van die beheerstelsel om 'n suurkonsentrasie stelpunt te volg getoets. Daar is bevind dat die kaskadestruktuur die suurkonsentrasie minder nougeset beheer as die basisgeval (met 'n IAE wat 124% en 80.6% hoër is vir die twee toetse), maar dat dit die variasie in die vastestoffraksie in dieselfde tenk (40.8% vermindering van die IAE in die eerste toets) en in die temperatuur van die eerste kompartement (73.6% vermindering van die IAE in die tweede toets) beduidend verminder. Daar word aanbeveel dat die relatiewe effekte van hierdie drie veranderlikes op logingsoptrede ondersoek moet word, met die gebruik van 'n model wat logingsreaksies in die outoklaaf akkuraat voorspel.

Essa tese teve como objetivo o estudo das mineralizações de ouro e metais base do Projeto Coringa, localizado na porção sudoeste da Província Mineral do Tapajós, no Cráton Amazônico. A mineralização é composta por diversos veios e zonas de vênulas hospedadas em zonas de falhas em vulcânicas e vulcanoclásticas félsicas cálcio-alcalinas de ca. 1,97 Ga, anteriomente consideradas como pertencentes ao Grupo Uatumã. O estudo permitiu a caracterização de unidades vulcânicas riolíticas, incluindo grandes volumes de rochas vulcanoclásticas e epiclásticas, bem como corpos de andesitos, dacitos e riodacitos, de granitos granofíricos e de pórfiros de composições e idades diversas. Como embasamento das rochas supracrustais foram identificados granitos e granodioritos plutônicos de idade de ca 2,0 Ga. As rochas vulcânicas constituem predominantemente domos de riolito com raros derrames associados e, subordinadamente, diques. Geoquimicamente foram caracterizados como formados em ambiente de margem continental ativa por magmas originados predominantemente na crosta inferior, com possíveis contaminações crustais. Dois conjuntos de riolitos foram identificados, nomeados como Riolito I e Riolito II. O primeiro, de idade de cristalização variando entre 1975 e 1967 Ma (U?Pb SHRIMP em zircão), se caracteriza por sua cor escura, predominantemente negra. Esses compõem predominante os domos. O Riolito II, de idade de ca. 1966 Ma (U-Pb SHRIMP em zircão), é rico em lithophysae e tem cores marrom-avermelhadas e ocorrem predominantemente como diques. As rochas vulcanoclásticas são predominantemente brechas e aglomerados vulcânicos, lapilli-tufos e tufos líticos e de cristais. Subordinadamente foram verificados corpos de welded-tuffs reológicamente deformados formados por fluxos de ignimbritos. Nas vulcanoclásticas predominam fragmentos de riolitos, com ocorrência de um dos tipos de riolito em alguns depósitos ou de ambos em outros, mas também estão presentes fragmentos de rochas hidrotermalizadas e, mais raramente, de rochas andesíticas, dacíticas e riodacíticas. Os cristais e fragmentos de cristais são predominantemente de feldspato potássico e de quartzo, comumente com relíquias de hábito bipiramidado e com fraturas conchoidais resultantes de atividades explosivas. A matriz foi muitas vezes vítrea, conforme atestado pelas texturas esferulíticas cristalizadas. Uma idade U-Pb SHRIMP em zircão obtido para essas rochas resultou em ca. 1966 Ma. As rochas vulcânicas e vulcanoclásticas estudadas foram anteriormente cartografadas como pertencentes ao Grupo Iriri, mas as idades indicam que esse evento vulcânico antecedeu esse magmatismo em pelo menos 90 Ma. Três tipos dos pórfiros foram idenficados, com composições variando de riolítica a riodacítica, com granulação grossa a fina e com matriz muito fina a afanítica. Esses se associam a estruturas circulares menores em planta, com fraturas radiadas, sugerindo comporem pequenos stocks. Suas idades de cristalização variam entre 1959 e 1980 Ma (U-Pb SHRIMP em zircão), indicando, dentro dos erros, formação contemporânea ao mesmo evento que gerou as rochas vulcânicas. Entretanto, as variações composicionais e geoquímicas sugerem fontes de magmas distintas. Em alguns corpos observam-se xenólitos de vulcânicas e de granito granofírico fino, assim como fragmentos de pórfiros nas rochas vulcanoclásticas, indicando ter havido diversos estágios de intrusão de pórfiros na região. Também ocorrem diversos corpos de granitos intrusivos nas sequências vulcânicas, mas outros corpos parecem ser anteriores ao vulcanismo. Suas idades variam entre 1959 e 1980 Ma (U-Pb SHRIMP em zircão). O principal corpo formado por granito é granofírico com abundantes cavidades miarolíticas, indicando ambiente crustal de colocação rasa. Um corpo de granodiorito de granulação grossa, de idade semelhante (ca. 1955 Ma, U-Pb SHRIMP em zircão), com características típicas de ambiente de cristalização mais profundo, foi também identificado na área. Essas rochas constam nos mapas geológicos como pertencentes às suítes Parauari e Maloquinha, mas as idades são mais antigas que as das rochas da Suite Intrusiva Parauari, e suas características geoquímicas cálcio-alcalinas e as idades não permitem correlações com as rochas da Suíte Intrusiva Maloquinha. O embasamento das unidades vulcânicas na região consta nos mapas geológicos como sendo formado por rochas da Suite Intrusiva Parauari e, mais a sudoeste, aflorariam rochas da Suíte Intrusiva Creporizão, formada basicamente por tonalitos e granodioritos. No entanto, no embasamento das rochas vulcânicas foram identificados granitos finos cinzas a levemente rosados, com idades variando de ca. 2123 Ma a ca. 2023 Ma (U-Pb SHRIMP em zircão), também mais antigas que as unidades previamente consideradas, além de granodioritos. Os pórfiros, as rochas vulcânicas e vulcanoclásticas, e em menor grau os granitos, foram hidrotermalizados em extensos sistemas hidrotermais, tendo sido reconhecidas zonas com metassomatismo potássico e alterações propilítica, sericítica (por vezes com adulária) e argílicas, além de carbonatização com calcita manganesífera e silicificação, todas em intensidades muito variadas. Nas zonas mineralizadas e nas suas proximidades, a alteração hidrotermal é, tipicamente, representada por forte alteração sericítica, com carbonatos subordinados em algumas áreas. As mineralizações se associam predominantemente com forte alteração sericítica com adulária, silicificação, sulfetização e, mais localmente, carbonatização. As alterações hidrotermais nos riolitos e nas rochas vulcanoclásticas e, em parte, também nos pórfiros, ocorrem nos estilos pervasivo e, principalmente, fissural. O metassomatismo potássico foi caracterizado pela associação de feldspato potássico + biotita secundária ± quartzo, a alteração propilítica por clorita + epidoto + quartzo + albita ± carbonatos ± pirita, a alteração sericítica por quartzo + sericita + sulfetos ou quartzo + sericita + adulária, a alteração argílica por argilo-minerais com com illita predominante, a alteração carbonática pela calcita manganesífera e a sulfetização por pirita predominante, com calcopirita, bornita, calcocita, esfalerita e galena subordinados. Entretanto, pode haver concentração de um ou mais desses minerais em algumas áreas ou veios. A mineralização de ouro e de metais de base ocorre predominantemente em veios e vênulas de quartzo estruturalmente controlados por falhas rúpteis. Apresenta caráter polimetálico polifásico, tendo comumente a associação galena + pirita + calcopirita ± esfalerita ± ouro ± electrum ± prata. Os veios mineralizados parecem se concentrar nos domos do Riolito I e nas suas proximidades, o que, conjuntamente com o tipo epitermal da mineralização, sugere uma relação genética entre a formação dos domos e a intrusão dos pórfiros com a deposição dos metais preciosos e de base. Entretanto, diques do Riolito II hidrotermalizados podem também ocorrer associados às mineralizações. Adicionalmente, zonas de stockworks intensamente hidrotermalizadas e com indícios de sulfetos de metais de base estão presentes na área, sugerindo também potencial para ocorrência de mineralizações do tipo pórfiro nesse evento magmático datado em ca. 1,97 Ga. A mineralogia, os modos de ocorrência, a associação com as hospedeiras, os zonamentos e a evolução fluidal são típicas de sistemas magmáticos-hidrotermais epitermais rasos. A presença de adulária nas mineralizações permite caracterizar esses sistemas mineralizantes como epitermais low-sulfidation e a presença de carbonatos manganesíferos e a abundância de metais de base evidenciam gradações para sistemas intermediate-sulfidation. / This thesis had as objective the study of the gold and base metal mineralization of the Coringa Prospect, located in the southwest portion of the Tapajós Mineral Province in the Amazonian Craton. The mineralization is hosted in a fault zone with vein and veinlets associated to volcanic and volcanoclastic calc-alkaline rocks with ca. 1.97 Ga, before considered related to the Uatuma Group. This study allowed to characterize rhyolitic volcanic units, (including volcanoclastic and epiclastic components), as well as andesites, dacites and rhyodacites, granophyric granite, and porphyries of different composition and ages. Plutonic rocks ca. 2,0 Ga were identified, where granites and granodiorites represent the basement of this volcanic sequence. The volcanic rocks comprise predominantly rhyolite domes with associated unusual flows) and subordinate dikes. They were formed in active continental margin, with magmas generated predominantly in the lower crust, with possible crustal contamination. Two sets of rhyolites have been identified, named Rhyolite I and Rhyolite II. The first occurs as domes, and is characterized by its dark color, predominantly black, and has U-Pb SHRIMP ages in zircon between 1975 and 1967 Ma.. The Rhyolite II, whose age is ca. 1966 Ma, occurs in dikes, is enriched in lithophysae and it has reddish-brown color. The volcaniclastic rocks encompass breccias, volcanic agglomerates, lapilli-tuff and tuff with lithic and crystal fragments and, subordinate, rheologically-deformed welded tuffs by ignimbrite flows. The rhyolite fragments predominate in the volcanoclastic rocks, with occurrence of one type of rhyolite in some deposits or both in others. Fragments of hydrothermally altered rocks and, more rarely, of andesitic, dacitic and rhyodacitic rocks and porphyries have been also recognized. The crystals and crystal fragments are predominantly of potassic feldspar and quartz, often with remains as result of explosive activities. The groundmass is proven by spherulitic textures. An U-Pb SHRIMP age in zircon obtained for these rocks resulted in ca. 1966 Ma. Volcanic and volcanoclastic rocks, before considered related to Iriri Group, show ages 90 Ma older than this volcanic event. Three porphyry samples were dated, varying from rhyolitic to rhyodacitic, coarse to fine-grained and aphanitic matrix. They are associated to small circular structures, with radial fractures, suggesting the presence of small stocks. Crystallization ages between 1959 and 1980 Ma (U-Pb SHRIMP in zircon), indicate, within the age errors, that the porphyries and volcanic rocks are coeval and may be formed in the same event. However, the compositional variations and geochemistry data suggest different sources. In some bodies is possible to find xenoliths of volcanics and fine-grained granophyric granite. Also were described porphyry fragments in volcaniclastic rocks and as intrusions in fine-grained granophyric granite, indicating different events of porphyry intrusion in the region. Several bodies of granitic intrusive rocks in the volcanic sequences have been also characterized, and their ages vary between 1959 and 1980 Ma (U-Pb SHRIMP in zircon). The main granophyric granite body with abundant miarolitic cavities indicates its emplacement in shallow crustal environment. A coarse-grained granodiorite of similar age (ca. 1955 Ma, U-Pb SHRIMP in zircon), shows typical characteristics that reflect emplacement in deep crustal environment. These rocks of this region were considered as part of the Parauari and Maloquinha suites, but their ages indicate that these rocks are older than those suites and their calc-alkaline geochemistry patterns and age do not allow correlation with the rocks of Maloquinha suite. The basement of the volcanic units has been previously attributed to the Parauari Intrusive Suite and to the Creporizão Intrusive Suite, composed mainly of tonalite and granodiorite. However, in the Coringa area, the basement is represented by fine-grained, gray to pinkish granite with ages ranging from ca. 2123 Ma to ca. 2023 Ma, which are also older than the units previously considered. Porphyries, volcanics, volcanoclastics and granites were altered by hydrothermal fluids in different type and styles, including potassium metasomatism, propylitic, sericitic (sometimes with adularia) and argillic alteration. Also were identified carbonate with manganoan calcite and variable intensity of silicification. At mineralization zones and in its vicinity, hydrothermal alteration is typically represented by strong sericitic alteration, with carbonates in some places. The mineralized zones are associated with sericitic alteration (with adularia), silicification, sulfidization and carbonation. Hydrothermal alteration occurs in pervasive style, but mainly in fissural style, and it is associated to both types of rhyolites and volcanoclastic rocks, and partially affects the porphyry lithotypes. Potassium metasomatism is evidenced by association of potassium feldspar + biotite ± quartz, propylitic alteration by chlorite + epidote + quartz + albite ± carbonate ± pyrite, sericitic alteration by quartz + sericite + quartz + sulfide or sericite + adularia, argillic predominantly with illite carbonate by manganoan calcite, silicification and sulfide formation, with chalcopyrite, bornite, chalcocite, sphalerite and garnet. The gold and base metal mineralization occurs predominantly in veins and quartz veinlets, which are structurally controlled by brittle faults. The mineralization is polymetallic and polyphasic, and commonly is represented by pyrite + galena + chalcopyrite ± sphalerite ± gold ± silver ± electrum. The mineralized veins seem to focus in the Rhyolite I domes and its neighbor areas, which, together with the type of epithermal mineralization suggest a genetic relationship between the formation of domes and the intrusion of porphyries with the precious and base metals deposition. However, dikes of Rhyolite II hydrothermalized occur associated to mineralization. Additionally, intense hydrothermally-altered stockwork zones with evidences of base metal mineralization have been identified, suggesting a potential for the occurrence of porphyry-type mineralization related to this ca. 1.97 Ga magmatic event. The mineralogy, the occurrence mode, the relationship with the host rocks, the zoning and fluid evolution are typical of shallow epithermal magmatic-hydrothermal systems. The presence of adularia in mineralization allows its classification as low-sulfidation epithermal. Additionally, the presence of manganoan carbonates and the abundance of base metals point to gradations to intermediate-sulfidation epithermal systems.

The research in this study consisted of two strands. The first consists of noble metal geochemical studies and the second involves base metal supergene processes. The precious metal geochemistry carried out in the scope of this thesis involves palladium and tellurium geochemistry, surface chemistry studies of palladium-bismuth- and tellarium-bearing synthetic minerals, and electrochemical determinations of the inactivity of a variety of primary telluride minerals and alloys. Two new minerals have been found in deposits near Broken Hill, N.S.W. The second section of the research concerns itself with supergene processes in two copper-bearing orebodies. This was carried out by designing a method utilising solution equilibria to predict whether secondary mineral species are precipitating or dissolving in the supergene zones of the Girilambone, N.S.W. and North Mungana, Qld. orebodies. Results found could be used to develop new geochemical prospecting methods in the regions discussed. / Doctor of Philosophy (PhD)

Essa tese teve como objetivo o estudo das mineralizações de ouro e metais base do Projeto Coringa, localizado na porção sudoeste da Província Mineral do Tapajós, no Cráton Amazônico. A mineralização é composta por diversos veios e zonas de vênulas hospedadas em zonas de falhas em vulcânicas e vulcanoclásticas félsicas cálcio-alcalinas de ca. 1,97 Ga, anteriomente consideradas como pertencentes ao Grupo Uatumã. O estudo permitiu a caracterização de unidades vulcânicas riolíticas, incluindo grandes volumes de rochas vulcanoclásticas e epiclásticas, bem como corpos de andesitos, dacitos e riodacitos, de granitos granofíricos e de pórfiros de composições e idades diversas. Como embasamento das rochas supracrustais foram identificados granitos e granodioritos plutônicos de idade de ca 2,0 Ga. As rochas vulcânicas constituem predominantemente domos de riolito com raros derrames associados e, subordinadamente, diques. Geoquimicamente foram caracterizados como formados em ambiente de margem continental ativa por magmas originados predominantemente na crosta inferior, com possíveis contaminações crustais. Dois conjuntos de riolitos foram identificados, nomeados como Riolito I e Riolito II. O primeiro, de idade de cristalização variando entre 1975 e 1967 Ma (U?Pb SHRIMP em zircão), se caracteriza por sua cor escura, predominantemente negra. Esses compõem predominante os domos. O Riolito II, de idade de ca. 1966 Ma (U-Pb SHRIMP em zircão), é rico em lithophysae e tem cores marrom-avermelhadas e ocorrem predominantemente como diques. As rochas vulcanoclásticas são predominantemente brechas e aglomerados vulcânicos, lapilli-tufos e tufos líticos e de cristais. Subordinadamente foram verificados corpos de welded-tuffs reológicamente deformados formados por fluxos de ignimbritos. Nas vulcanoclásticas predominam fragmentos de riolitos, com ocorrência de um dos tipos de riolito em alguns depósitos ou de ambos em outros, mas também estão presentes fragmentos de rochas hidrotermalizadas e, mais raramente, de rochas andesíticas, dacíticas e riodacíticas. Os cristais e fragmentos de cristais são predominantemente de feldspato potássico e de quartzo, comumente com relíquias de hábito bipiramidado e com fraturas conchoidais resultantes de atividades explosivas. A matriz foi muitas vezes vítrea, conforme atestado pelas texturas esferulíticas cristalizadas. Uma idade U-Pb SHRIMP em zircão obtido para essas rochas resultou em ca. 1966 Ma. As rochas vulcânicas e vulcanoclásticas estudadas foram anteriormente cartografadas como pertencentes ao Grupo Iriri, mas as idades indicam que esse evento vulcânico antecedeu esse magmatismo em pelo menos 90 Ma. Três tipos dos pórfiros foram idenficados, com composições variando de riolítica a riodacítica, com granulação grossa a fina e com matriz muito fina a afanítica. Esses se associam a estruturas circulares menores em planta, com fraturas radiadas, sugerindo comporem pequenos stocks. Suas idades de cristalização variam entre 1959 e 1980 Ma (U-Pb SHRIMP em zircão), indicando, dentro dos erros, formação contemporânea ao mesmo evento que gerou as rochas vulcânicas. Entretanto, as variações composicionais e geoquímicas sugerem fontes de magmas distintas. Em alguns corpos observam-se xenólitos de vulcânicas e de granito granofírico fino, assim como fragmentos de pórfiros nas rochas vulcanoclásticas, indicando ter havido diversos estágios de intrusão de pórfiros na região. Também ocorrem diversos corpos de granitos intrusivos nas sequências vulcânicas, mas outros corpos parecem ser anteriores ao vulcanismo. Suas idades variam entre 1959 e 1980 Ma (U-Pb SHRIMP em zircão). O principal corpo formado por granito é granofírico com abundantes cavidades miarolíticas, indicando ambiente crustal de colocação rasa. Um corpo de granodiorito de granulação grossa, de idade semelhante (ca. 1955 Ma, U-Pb SHRIMP em zircão), com características típicas de ambiente de cristalização mais profundo, foi também identificado na área. Essas rochas constam nos mapas geológicos como pertencentes às suítes Parauari e Maloquinha, mas as idades são mais antigas que as das rochas da Suite Intrusiva Parauari, e suas características geoquímicas cálcio-alcalinas e as idades não permitem correlações com as rochas da Suíte Intrusiva Maloquinha. O embasamento das unidades vulcânicas na região consta nos mapas geológicos como sendo formado por rochas da Suite Intrusiva Parauari e, mais a sudoeste, aflorariam rochas da Suíte Intrusiva Creporizão, formada basicamente por tonalitos e granodioritos. No entanto, no embasamento das rochas vulcânicas foram identificados granitos finos cinzas a levemente rosados, com idades variando de ca. 2123 Ma a ca. 2023 Ma (U-Pb SHRIMP em zircão), também mais antigas que as unidades previamente consideradas, além de granodioritos. Os pórfiros, as rochas vulcânicas e vulcanoclásticas, e em menor grau os granitos, foram hidrotermalizados em extensos sistemas hidrotermais, tendo sido reconhecidas zonas com metassomatismo potássico e alterações propilítica, sericítica (por vezes com adulária) e argílicas, além de carbonatização com calcita manganesífera e silicificação, todas em intensidades muito variadas. Nas zonas mineralizadas e nas suas proximidades, a alteração hidrotermal é, tipicamente, representada por forte alteração sericítica, com carbonatos subordinados em algumas áreas. As mineralizações se associam predominantemente com forte alteração sericítica com adulária, silicificação, sulfetização e, mais localmente, carbonatização. As alterações hidrotermais nos riolitos e nas rochas vulcanoclásticas e, em parte, também nos pórfiros, ocorrem nos estilos pervasivo e, principalmente, fissural. O metassomatismo potássico foi caracterizado pela associação de feldspato potássico + biotita secundária ± quartzo, a alteração propilítica por clorita + epidoto + quartzo + albita ± carbonatos ± pirita, a alteração sericítica por quartzo + sericita + sulfetos ou quartzo + sericita + adulária, a alteração argílica por argilo-minerais com com illita predominante, a alteração carbonática pela calcita manganesífera e a sulfetização por pirita predominante, com calcopirita, bornita, calcocita, esfalerita e galena subordinados. Entretanto, pode haver concentração de um ou mais desses minerais em algumas áreas ou veios. A mineralização de ouro e de metais de base ocorre predominantemente em veios e vênulas de quartzo estruturalmente controlados por falhas rúpteis. Apresenta caráter polimetálico polifásico, tendo comumente a associação galena + pirita + calcopirita ± esfalerita ± ouro ± electrum ± prata. Os veios mineralizados parecem se concentrar nos domos do Riolito I e nas suas proximidades, o que, conjuntamente com o tipo epitermal da mineralização, sugere uma relação genética entre a formação dos domos e a intrusão dos pórfiros com a deposição dos metais preciosos e de base. Entretanto, diques do Riolito II hidrotermalizados podem também ocorrer associados às mineralizações. Adicionalmente, zonas de stockworks intensamente hidrotermalizadas e com indícios de sulfetos de metais de base estão presentes na área, sugerindo também potencial para ocorrência de mineralizações do tipo pórfiro nesse evento magmático datado em ca. 1,97 Ga. A mineralogia, os modos de ocorrência, a associação com as hospedeiras, os zonamentos e a evolução fluidal são típicas de sistemas magmáticos-hidrotermais epitermais rasos. A presença de adulária nas mineralizações permite caracterizar esses sistemas mineralizantes como epitermais low-sulfidation e a presença de carbonatos manganesíferos e a abundância de metais de base evidenciam gradações para sistemas intermediate-sulfidation. / This thesis had as objective the study of the gold and base metal mineralization of the Coringa Prospect, located in the southwest portion of the Tapajós Mineral Province in the Amazonian Craton. The mineralization is hosted in a fault zone with vein and veinlets associated to volcanic and volcanoclastic calc-alkaline rocks with ca. 1.97 Ga, before considered related to the Uatuma Group. This study allowed to characterize rhyolitic volcanic units, (including volcanoclastic and epiclastic components), as well as andesites, dacites and rhyodacites, granophyric granite, and porphyries of different composition and ages. Plutonic rocks ca. 2,0 Ga were identified, where granites and granodiorites represent the basement of this volcanic sequence. The volcanic rocks comprise predominantly rhyolite domes with associated unusual flows) and subordinate dikes. They were formed in active continental margin, with magmas generated predominantly in the lower crust, with possible crustal contamination. Two sets of rhyolites have been identified, named Rhyolite I and Rhyolite II. The first occurs as domes, and is characterized by its dark color, predominantly black, and has U-Pb SHRIMP ages in zircon between 1975 and 1967 Ma.. The Rhyolite II, whose age is ca. 1966 Ma, occurs in dikes, is enriched in lithophysae and it has reddish-brown color. The volcaniclastic rocks encompass breccias, volcanic agglomerates, lapilli-tuff and tuff with lithic and crystal fragments and, subordinate, rheologically-deformed welded tuffs by ignimbrite flows. The rhyolite fragments predominate in the volcanoclastic rocks, with occurrence of one type of rhyolite in some deposits or both in others. Fragments of hydrothermally altered rocks and, more rarely, of andesitic, dacitic and rhyodacitic rocks and porphyries have been also recognized. The crystals and crystal fragments are predominantly of potassic feldspar and quartz, often with remains as result of explosive activities. The groundmass is proven by spherulitic textures. An U-Pb SHRIMP age in zircon obtained for these rocks resulted in ca. 1966 Ma. Volcanic and volcanoclastic rocks, before considered related to Iriri Group, show ages 90 Ma older than this volcanic event. Three porphyry samples were dated, varying from rhyolitic to rhyodacitic, coarse to fine-grained and aphanitic matrix. They are associated to small circular structures, with radial fractures, suggesting the presence of small stocks. Crystallization ages between 1959 and 1980 Ma (U-Pb SHRIMP in zircon), indicate, within the age errors, that the porphyries and volcanic rocks are coeval and may be formed in the same event. However, the compositional variations and geochemistry data suggest different sources. In some bodies is possible to find xenoliths of volcanics and fine-grained granophyric granite. Also were described porphyry fragments in volcaniclastic rocks and as intrusions in fine-grained granophyric granite, indicating different events of porphyry intrusion in the region. Several bodies of granitic intrusive rocks in the volcanic sequences have been also characterized, and their ages vary between 1959 and 1980 Ma (U-Pb SHRIMP in zircon). The main granophyric granite body with abundant miarolitic cavities indicates its emplacement in shallow crustal environment. A coarse-grained granodiorite of similar age (ca. 1955 Ma, U-Pb SHRIMP in zircon), shows typical characteristics that reflect emplacement in deep crustal environment. These rocks of this region were considered as part of the Parauari and Maloquinha suites, but their ages indicate that these rocks are older than those suites and their calc-alkaline geochemistry patterns and age do not allow correlation with the rocks of Maloquinha suite. The basement of the volcanic units has been previously attributed to the Parauari Intrusive Suite and to the Creporizão Intrusive Suite, composed mainly of tonalite and granodiorite. However, in the Coringa area, the basement is represented by fine-grained, gray to pinkish granite with ages ranging from ca. 2123 Ma to ca. 2023 Ma, which are also older than the units previously considered. Porphyries, volcanics, volcanoclastics and granites were altered by hydrothermal fluids in different type and styles, including potassium metasomatism, propylitic, sericitic (sometimes with adularia) and argillic alteration. Also were identified carbonate with manganoan calcite and variable intensity of silicification. At mineralization zones and in its vicinity, hydrothermal alteration is typically represented by strong sericitic alteration, with carbonates in some places. The mineralized zones are associated with sericitic alteration (with adularia), silicification, sulfidization and carbonation. Hydrothermal alteration occurs in pervasive style, but mainly in fissural style, and it is associated to both types of rhyolites and volcanoclastic rocks, and partially affects the porphyry lithotypes. Potassium metasomatism is evidenced by association of potassium feldspar + biotite ± quartz, propylitic alteration by chlorite + epidote + quartz + albite ± carbonate ± pyrite, sericitic alteration by quartz + sericite + quartz + sulfide or sericite + adularia, argillic predominantly with illite carbonate by manganoan calcite, silicification and sulfide formation, with chalcopyrite, bornite, chalcocite, sphalerite and garnet. The gold and base metal mineralization occurs predominantly in veins and quartz veinlets, which are structurally controlled by brittle faults. The mineralization is polymetallic and polyphasic, and commonly is represented by pyrite + galena + chalcopyrite ± sphalerite ± gold ± silver ± electrum. The mineralized veins seem to focus in the Rhyolite I domes and its neighbor areas, which, together with the type of epithermal mineralization suggest a genetic relationship between the formation of domes and the intrusion of porphyries with the precious and base metals deposition. However, dikes of Rhyolite II hydrothermalized occur associated to mineralization. Additionally, intense hydrothermally-altered stockwork zones with evidences of base metal mineralization have been identified, suggesting a potential for the occurrence of porphyry-type mineralization related to this ca. 1.97 Ga magmatic event. The mineralogy, the occurrence mode, the relationship with the host rocks, the zoning and fluid evolution are typical of shallow epithermal magmatic-hydrothermal systems. The presence of adularia in mineralization allows its classification as low-sulfidation epithermal. Additionally, the presence of manganoan carbonates and the abundance of base metals point to gradations to intermediate-sulfidation epithermal systems.