Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: At Skorpion Zinc mine, in south-west Namibia, zinc oxide ore is refined through sulphuric acid leaching, solvent extraction, electrowinning and casting of the final 99.995 % Zn metal. Over the last four years, the rare earth element concentrations, with particular reference to Y, Yb, Er and Sc, have significantly increased in the circulating electrolyte and the zinc-stripped organic phase streams in the electrowinning and solvent extraction processes. This project had two main objectives: firstly, the effect(s) of rare earths on the zinc solvent extraction and electrowinning processes were to be determined; based on these results, the second objective was to find a suitable method for removing rare earth elements from the organic phase during zinc solvent extraction. The investigation into the effect of the rare earths on zinc electrowinning showed that an increase of 100 mg/l in the electrolyte Y concentration caused a decrease of 6 % in current efficiency. The elemental order of decreasing current efficiency was found to be: Y > Yb > Er > Sc. In the zinc solvent extraction process, it was found that an increase in the total organic rare earth elements and iron concentration from 3100 to 6250 mg/l resulted in doubled viscosity and an increase in phase disengagement time from 100 to 700 seconds. The organic zinc loading capacity after two extraction stages was reduced by 1 – 3 g/l depending on the pregnant leach solution used. The detrimental effect of rare earth elements on solvent extraction and electroplating of zinc therefore justified the development of a rare earth element removal process. Stripping of low concentrations of rare earth elements from 40% D2EHPA diluted in kerosene to produce a clean organic for zinc extraction was investigated using bench-scale experiments in a glass jacketed mixing cylinder. For the rare earths, the best stripping agent was found to be H2SO4, followed by HCl and then HNO3. Hydrochloric acid achieved better Fe stripping than sulphuric acid. Acid concentration was tested in the range of 1 to 7 M, organic-to-aqueous ratio for the range of 0.25 to 6.0 and temperatures between 30 and 55 °C. More than 80% stripping of yttrium and erbium could be achieved at an optimum hydrochloric acid concentration of 5 M and more than 90% rare earth element (specifically Y, Er, Yb) stripping from the organic phase could be achieved with 5 M sulphuric acid. Stripping was improved by reducing the organic-to-aqueous ratio to as low as 0.5 and increasing the temperature. Stripping increased with increasing temperature in an S-shaped curve, flattening off at 50°C. The effect of O:A ratio was more significant than the effect of temperature on rare earth stripping. The results showed good repeatability, and were not limited by the rare earth concentration, agitation rate or equilibrium time in the range of set points used in the experiments. Statistical models were compiled to fit the experimental data obtained for Y, Yb, Er and Fe when stripped with sulphuric and hydrochloric acid respectively. All models showed dependence on the acid concentration and squared-concentration and interaction effects between the O:A ratio and temperature and stripping agent concentration were significant. The models were compiled for the experimental data obtained from stripping synthetically prepared organic and then tested on results obtained when stripping the plant organic phase. The following three process solutions were discussed for implementation on a plant scale for the removal of rare earths from the organic phase during zinc solvent extraction: Sulphuric acid stripping mixer settler or stripping column, improvement of available HCl stripping section and replacement of the organic inventory. The possibility of an oxalic acid precipitation process to obtain value from the rare earths as by-product was also discussed. It was concluded that the current process that uses HCl to strip off iron and rare earths would be the best practically and financially feasible process. Value can be gained from the rare earths if a rare earth element - oxalic acid precipitation section that is financially feasible can be established. / AFRIKAANSE OPSOMMING: By Skorpion Zinc myn, in suidwes Namibië, word sinkoksied erts gesuiwer deur middel van swaelsuur-loging, oplosmiddel ekstraksie, elektroplatering en gieting van die finale 99.995 % Zn metaal. Oor die afgelope vier jaar het die seldsame aardmetale konsentrasie, spesifiek Y, Yb, Er en Sc, noemenswaardig in die sirkulerende elektroliet en sink-gestroopte organiese fase toegeneem. Hierdie projek het twee hoofdoelstellings gehad: eerstens moes die effek van seldsame aardmetale op die sink oplosmiddel ekstraksie en elektroplatering prosesse bepaal word; gebaseer op hierdie resultate, was die tweede doelstelling om ‘n geskikte metode vir die verwydering van seldsame aardmetale vanaf die organiese fase gedurende sink oplosmiddel ekstraksie te vind. Die ondersoek na die effek van seldsame aardmetale op sink elektroplatering het gewys dat ‘n verhoging van 100 mg/l in die elektroliet Y konsentrasie ‘n verlaging van 6 % in kragdoeltreffendheid veroorsaak het. Die element-orde van verminderende kragdoeltreffendheid was Y > Yb > Er > Sc. Vir die sink oplosmiddel ekstraksie proses, is gevind dat ‘n verhoging in die totale organiese seldsame aardmetaal- en yster konsentrasie van 3100 tot 6250 mg/l ‘n verdubbelde viskositeit en ‘n verlenging in faseskeidingstyd van 100 tot 700 sekondes tot gevolg gehad het. Die organiese sink ladingskapasiteit na twee ekstraksie stappe is met 1 – 3 g/l verminder afhangende van die logings oplossing wat gebruik is. Die nadelige effek van seldsame aardmetale op oplosmiddel ekstraksie en sink elektroplatering het die ontwikkeling van ‘n seldsame aardmetale verwyderingsproses regverdig. Die verwydering van lae konsentrasies seldsame aardmetale vanaf die D2EHPA-keroseen organiese fase om ‘n skoon organiese fase vir sink-ekstraksie te verkry is ondersoek deur banktoetsskaal eksperimente. Vir die seldsame aardmetale is bevind dat H2SO4 die beste stropingsagent is, gevolg deur HCl en dan HNO3. Soutsuur het beter yster verwydering as swaelsuur bewerkstellig. Suurkonsentrasies van 1 tot 7 M, O:A verhoudings van 0.25 tot 6 en temperature tussen 30 en 55°C is getoets. Meer as 80% verwydering van yttrium en erbium kon bereik word met ‘n optimum HCl konsentrasie van 5 M en meer as 90% seldsame aardmetale (spesifiek Y, Er en Yb) verwydering vanaf die organiese fase met 5 M swaelsuur. Seldsame aardmetale en yster verwydering kon verbeter word deur die organies-tot-waterfase (O:A) verhouding te verminder tot so laag as 0.5 en deur die temperatuur te verhoog. Stroping het in ‘n S-kurwe verhoog soos die temperatuur verhoog het, en het afgeplat teen 50°C. Die effek van die O:A verhouding was belangriker as die effek van temperatuur op stroping. Die resultate het goeie herhaalbaarheid gewys, en is nie deur massaoordrag beperk nie. Statistiese modelle is saamgestel om die eksperimentele data wat vir Y, Yb, Er en Fe verkry is vir stroping met swaelsuur en soutsuur te pas. Al die modelle het afhanklikheid van die suurkonsentrasie en kwadratiese suurkonsentrasie gewys en interaksie effekte tussen die O:A verhouding, temperatuur en suurkonsentrasie was belangrik. Die modelle is saamgestel vir die eksperimentele data wat verkry is vanaf stroping van ‘n sintetiese organiese fase en is toe getoets op resultate wat verkry is vanaf stroping van die aanleg se organiese fase. Die volgende drie proses-oplossings is oorweeg vir implementering op ‘n aanlegskaal vir die verwydering van seldsame aardmetale vanaf die organiese fase gedurende sink oplosmiddel ekstraksie: Swaelsuur stroping menger-afskeidingstenk of stropingskolom, verbetering van die bestaande HCl aanleg en vervanging van die organiese inventaris. ‘n Moontlike oksaalsuur presipitasie proses om waarde vanaf die seldsame aardmetale as by-produk te verkry is ook bespreek. Daar is tot die gevolgtrekking gekom dat die huidige proses wat HCl gebruik om yster en seldsame aardmetale van die organiese fase af te stroop, die beste praktiese en finansieel vatbare proses huidiglik is. Waarde kan vanaf die seldsame aardmetale verkry word as ‘n seldsame aardmetale – oksaalsuur presipitasie afdeling wat finansieel haalbaar is daargestel kan word.

Chemical weathering reactions are important for the physical, chemical, and biological development of the critical zone. We present findings from aqueous phase chemical analyses of surface and soil pore waters during a 15 month study in a small semi-arid mountain catchment of the Santa Catalina Mountain Critical Zone Observatory. Stream water geochemical solutes are sourced to two distinct locations - fractured bedrock baseflow stores and soil quickflow stores. Solid phase observations of albite, anorthite, and K-feldspar transformation to Ca-montmorillonite and kaolinite are supported by stream water saturation states calculated via a PHREEQC geochemical model. While differences in mineral assemblages, soil depths, and horizonation suggest greater weathering in schist versus granite lithologies and in hillslope divergent versus convergent zones, soil pore water solute ratio analysis does not readily distinguish these differences. However, preliminary investigation of aqueous rare earth elements suggests detectable lithologic and landscape positional differences warranting focus for future research efforts.

Master of Science / Department of Geology / Matthew Totten / The REE distribution patterns and total concentrations of the organic matter of the Woodford shale reveal a potential avenue to investigate hydrocarbon maturation processes in a source rock. Ten samples of the organic matter fraction and 10 samples of the silicate-carbonate fraction of the Woodford shale from north central Oklahoma were analyzed by methods developed at KSU. Thirteen oil samples from Woodford Devonian oil and Mississippian oil samples were analyzed for REE also. REE concentration levels in an average shale range from 170 ppm to 185 ppm, and concentration levels in modern day plants occur in the ppb levels. The REE concentrations in the organic matter of the Woodford Shale samples analyzed ranged from 300 to 800 ppm. The high concentrations of the REEs in the Woodford Shale, as compared to the modern-day plants, are reflections of the transformations of buried Woodford Shale organic materials in post-depositional environmental conditions with potential contributions of exchanges of REE coming from associated sediments. The distribution patterns of REEs in the organic materials normalized to PAAS (post-Archean Australian Shale) had the following significant features: (1) all but two out of the ten samples had a La-Lu trend with HREE enrichment in general, (2) all but two samples showed Ho and Tm positive enrichments, (3) only one sample had positive Eu anomalies, (4) three samples had Ce negative anomalies, although one was with a positive Ce anomaly, (5) all but three out of ten had MREE enrichment by varied degrees. It is hypothesized that Ho and Tm positive anomalies in the organic materials of the Woodford Shale are reflections of enzymic influence related to the plant physiology. Similar arguments may be made for the Eu and the Ce anomalies in the Woodford Shale organic materials. The varied MREE enrichments are likely to have been related to some phosphate mineralization events, as the Woodford Shale is well known for having abundant presence of phosphate nodules. The trend of HREE enrichment in general for the Woodford Shale organic materials can be related to inheritance from sources with REE-complexes stabilized by interaction between the metals and carbonate ligands or carboxylate ligands or both. Therefore, a reasonable suggestion about the history of the REEs in the organic materials would be that both source and burial transformation effects of the deposited organic materials in association with the inorganic constituents had an influence on the general trend and the specific trends in the distribution patterns of the REEs. This study provides a valuable insight into the understandings of the REE landscapes in the organic fraction of the Woodford Shale in northern Oklahoma, linking these understandings to the REE analysis of an oil generated from the same source bed and comparing it to oil produced from younger Mississippian oil. The information gathered from this study may ultimately prove useful to trace the chemical history of oils generated from the Woodford Shale source beds.

Master of Science / Department of Geology / Matthew Totten / There are some who hold the view that liquid hydrocarbons in the upper Paleozoic formations in Kansas are being locally derived. It has been the long held belief that the liquid hydrocarbons found in Kansas have come from distant sources in Oklahoma. To shed further light on this issue about the origin of hydrocarbons in the upper Paleozoic formations in Kansas, a study was conducted to analyze the geochemical characteristics of REE in Lansing-Kansas City oils that were collected from several locations in a small area within Rooks County, Kansas. The total REE contents in these oils ranges from about 3.1 ng (or 10-12 gram) per Liter of oil to about 131 ng per Liter of oil. The pattern of relative distribution of the REEs for each oil sample has been constructed from values that were obtained by dividing the individual REE concentrations of a given oil sample by the respective concentrations of the REEs in a standard or a reference sample (such as PAAS, a representation of average argillaceous sediments in the crust that is commonly used for the analyses of a variety of crust originated sedimentary products). A standard- normalized relative distribution pattern of an oil sample can reveal an important history of chemical evolution of the oil of interest. The PAAS-normalized patterns of relative distribution of the REEs in the Lansing-Kansas City oils from Rooks County, Kansas are significantly diverse. Although nearly all oil samples investigated in this study have varied degrees of light REE-enrichment across the REE series from La to Sm, they differed in their relative Ce abundances. Some samples have positive Ce anomalies; some have negative Ce anomalies, and some others with the absence of any Ce anomaly. The oils also differed in their PAAS-normalized relative distribution of the middle rare earth elements (MREEs), ranging from Sm to Tb. All oil samples were relatively enriched in the MREEs, but with varied degrees of enrichment from a prominent one to almost a barely noticeable one. The oils differed in their relative distributions of Eu, as some were with a positive Eu anomaly, some with a negative Eu anomaly, and some with the absence of any Eu anomaly. The trends of the heavy rare earth elements (HREEs) from Tb to Lu among the oils ranged from nearly flat for the most oils to a progressive depletion across the series for few samples. Furthermore, the oils were varied in having prominently anomalous relative distributions, in some cases with a positive anomaly and in others with negative anomaly, for such elements as Tb, Ho, and Tm (MM-JS-04, MM-MC-3A, and MM-MC-01). The anomalies for Tb, Ho, Tm are reflections of enzyme activity of source material during its primary (growth) environment. The metals are known to be preferentially located at the active sites of the enzymes. The oils not only differed significantly in their REE-geochemical characteristics, they also had a wide range of K/Rb weight ratios from about 877 to about 2000. These high values are typically the ones that can be assigned to organic materials, well exceeding the range of values that are associated with common silicate minerals and rocks, having an average value of 250-350ppm. Different zones in the Lansing-Kansas City formations also show distinct REE distribution patterns. There are four broadly classified distribution patterns. MREE enrichment can be observed in samples with production from the middle Lansing-Kansas City zones (G-I). In samples with comingling Lansing-Kansas City zones, amplification of anomalies from differing source materials can be observed. The diversity in the REE distribution patterns and K/Rb ratios in oils collected from central Kansas makes a strong argument against long distance transportation from a distant source in Oklahoma

A cultura de citros exige aplicações constantes de fertilizantes para atingir níveis satisfatórios de produtividade. Fertilizantes contêm outros elementos químicos além daqueles de interesse, como, por exemplo, os elementos terras raras (ETR). Estudos mostram que aplicações de ETR podem aumentar o crescimento e a produtividade das plantas como também causar efeitos nocivos ao ambiente e ao homem. No Brasil, não é prática comum a adição de ETR em fertilizantes, porém alguns insumos contêm em sua composição. Os objetivos deste trabalho foram quantificar os ETR nos compartimentos planta, solo e insumos de agroecossistemas citrícolas, avaliar o modelo de distribuição, identificar as principais fontes de ETR e estudar os efeitos desses elementos na planta cítrica. Para determinação dos ETR, utilizou-se da análise por ativação neutrônica instrumental (INAA) e espectrometria de massas com plasma indutivamente acoplado (ICP-MS). Foram feitos experimentos no campo e em casa-de-vegetação. O experimento de campo foi realizado em quatro propriedades de citros, sendo duas sob sistema de produção orgânico e duas sob o sistema de produção convencional, na região de Borborema, SP, com a variedade Valência (Citrus sinensis L. Osbeck) enxertada sobre limão cravo (Citrus limonia Osbeck),. Amostraram-se 15 plantas em cada propriedade, sendo coletados folhas, frutos, solos e os principais insumos empregados. As concentrações de ETR nas folhas bem como o fator de transferência solo-planta foram semelhantes aos de plantas bioacumuladoras. As folhas assim como as partes do fruto apresentaram depleção de Ce. Na fruta cítrica, a concentração dos ETR apresentou a seguinte distribuição: casca > polpa > sementes = suco. As maiores concentrações de ETR nos insumos foram observadas para os fertilizantes fosfatados. O delineamento experimental utilizado nos dois experimentos em casa-de vegetação foi em blocos ao acaso. Nos experimentos em casa-de-vegetação com superfosfato simples e cloreto de lantânio realizou-se a semeadura de sementes de limão cravo em tubetes de polipropileno. Para o experimento com superfosfato simples, as plantas de limão cravo permaneceram nos tubetes por 6 meses e, a partir desse período, iniciou-se o transplante para sacos plásticos. Os tratamentos constituíram-se de diferentes doses de superfosfato simples (50 g, 100 g, 200 g, 400 g) aplicadas ao substrato. Após 2 meses, coletaram-se as plantas de limão cravo e analisaram-se as folhas e o caule. No experimento com cloreto de lantânio, a aplicação dos tratamentos (50 mg, 100 mg, 200 mg, 400 mg) deuse após 98 dias da semeadura. Três semanas após, coletaram-se as plantas. A planta de citros do estudo pode ser considerada uma bioacumuladora de ETR. Houve discriminação entre os sistemas de produção em 2005, 2006 e 2007 para Eu, Tb, Yb e Sc nos compartimentos solo e folha, com uma concentração significativamente (p<0,05) maior no sistema de produção orgânico. O limão cravo absorve ETR do fertilizante superfosfato simples. A planta de citros teve sua fisiologia alterada com a aplicação de lantânio, isto é, dependendo da dose pode haver um efeito benéfico ou prejudicial no crescimento, sugerindo seu potencial uso como fertilizante na citricultura / The citrus crop requires repeated application of fertilizer to achieve satisfactory levels of productivity. Fertilizers contain other chemical elements in addition to those of interest, such as the rare earth elements (REE). Some studies show that applications of REE may increase plant growth and productivity, but it can also be harmful to both the environment and man. In Brazil, adding REE to fertilizers is not a common practice, however it may be found in the composition of some inputs. The objectives of this study were to quantify the REE in plant, soil and inputs in citrus agroecosystems, to identify the inputs acting as REE sources to the citrus plant, to study the effects of REE in citrus and to evaluate the REE distribution model. The instrumental neutron activation analysis (INAA) and the mass spectrometry with inductively coupled plasma (ICP-MS) were performed to determine the REE. Field and greenhouse experiments were conducted. The field experiment was performed in four citrus properties, with Valencia variety (Citrus sinensis L. Osbeck) grafted onto \'Rangpur\' lime (Citrus limonia Osbeck), two under an organic production system and two under the conventional production system in the region of Borborema, SP. Fifteen plants were sampled in each property and leaves, fruits, soils and the main input used in these properties. REE concentrations in leaves as well as the REE soil-plant transfer factor were similar to those of bioaccumulator plants. Likewise the fruit parts, the leaves showed Ce depletion. The REE concentration in the citrus fruit was distributed as follows: skin > pulp > seeds = juice. The higher concentrations of REE in the inputs were determined for the phosphate fertilizers. The greenhouse experiments with simple superphosphate and lanthanum chloride included the sowing of \'Rangpur\' lime seeds in polypropylene tubes. Both greenhouse experiments had a randomized block design. For the simple superphosphate the \'Rangpur\' lime plants remained in the tubes for 6 months and then were transplanted into plastic bags. The treatments comprised different doses of simple superphosphate (50 g, 100 g, 200 g, 400 g) applied into the substrate. Two months later the \'Rangpur\' lime plants were collected and their leaves and stalk were analyzed. In the experiment with lanthanum chloride heptahydrate the application of the treatments (40 mg, 100 mg, 200 mg, 400 mg) occurred 98 days following sowing. Three weeks following the application of the lanthanum chloride the plants were collected. It can infer that this citrus plant can be considered a REE bioaccumulator. There was discrimination between the production system in 2005, 2006 and 2007 for Eu, Tb, Yb and Sc in the soil and leaves compartments, with a concentration significantly (p <0.05) higher in the organic production system. The \'Rangpur\' lime uptakes REE from the simple superphosphate fertilizer. The citrus plant physiology had changed with the application of lanthanum, ie depending on the dose may be a beneficial or harmful effect on growth, suggesting its potential use as fertilizer in citriculture

O complexo estuarino-lagunar de Cananéia-Iguape, localizado na porção sul do litoral do Estado de São Paulo, integra uma importante reserva ambiental e um ecossistema costeiro extremamente produtivo. A região abriga o canal do Valo Grande, construído há mais de 160 anos, o qual favorece a introdução água doce do rio Ribeira de Iguape diretamente no sistema estuarino contribuindo à importantes alterações biogeoquímicas como o aporte de nutrientes, metais e outros elementos pouco solúveis, que acabam tendo como destino os sedimentos. No presente trabalho foi realizada a coleta de amostras da coluna de água e de sedimentos de superfície ao longo do complexo estuarino-lagunar de Cananéia-Iguape e ambientes contíguos. Também houve a realização de perfis de sedimento na região sul do estuário, considerada mais preservada. O objetivo principal foi avaliar os processos que regem a distribuição dos Elementos Terras Raras (ETR) nos sedimentos do sistema, conhecendo as propriedades hidroquímicas do sistema, associando e comparando os ETR a outros elementos presentes em baixas concentrações, de modo natural ou resultantes de alterações de origem antrópica, utilizando padrões de fracionamento, anomalias e assinatura geoquímica de minerais que atuam na distribuição dos ETR verificando seu potencial para evidenciar a origem e interpretar níveis naturais e efeitos antrópicos aos quais o Complexo está submetido. Os resultados mostraram que as características hidroquímicas na região norte do Complexo encontram-se fortemente influenciadas pelo aporte de águas fluviais via Valo Grande e pelos processos biogeoquímicos associados a ele, enquanto a região sul apresentou-se mais conservada, mostrando equilíbrio biogeoquímico natural de sistemas estuarinos, oferecendo maior suporte à produção primária. Nos sedimentos de superfície, as concentrações elementares de Al, As, Ba, Ca, Cd, Co, Cr, Cs, Fe, Hg, Hf, P, Pb, Rb, Sb, Sc, Th, U, Zn, Zr e ETR* apresentaram distribuição bastante relacionada às características deposicionais/texturais, de forma que a maioria destes elementos tiveram maiores concentrações em regiões de baixa energia hidrodinâmica, no interior do rio Ribeira de Iguape e no mar Pequeno. Considerando como referência os valores guias de qualidade dos sedimentos canadenses (TEL e PEL), os elementos As, Cd, Pb, Cr, Hg e Zn apresentaram concentração abaixo dos valores que indicam frequente ocorrência de efeitos adversos nos organismos aquáticos (PEL), mas foi observado que em alguns locais, As, Cr, Pb e Zn superaram os valores de concentração que indicam uma baixa probabilidade de ocorrência de efeitos adversos à biota (TEL). Fatores de enriquecimento calculados com relação à crosta continental superior (FEUCC) e ao background geoquímico regional (FEBG) apontaram regiões onde ocorrem concentrações de Pb, P e Sb acima dos níveis considerados naturais, entretanto evidenciaram que os altos valores de As e Cr estariam relacionados a um enriquecimento natural dos sedimentos na região. No caso dos ETR, o FEUCC e FEBG indicaram enriquecimento na região do mar adjacente ao estuário e em estações no rio Ribeira e no Valo Grande. A aplicação de modelagem através da regressão múltipla linear mostrou que os valores, que seriam normalmente considerados anômalos, são naturais e refletem a presença de minerais pesados nestes locais. Outros elementos que parecem naturalmente enriquecidos onde há ocorrência minerais pesados são: As, Ca, Cr, Th, U, além dos elementos ditos sinalizadores, como Hf e Zr. Anomalias de Ce mostraram a possível relação com processos de oxidação de Ce+3 a Ce+4 mediada biológicamente nas zonas mais produtivas do estuário. Dos quatro perfis de sedimento obtidos na região sul do estuário, três mostraram seções com valores de FEUCC e FEBG para Pb que sugerem contribuição antrópica. Tais padrões decrescem em direção ao sul do sistema, porém praticamente não mostram variação temporal. Nenhuma concentração de Pb superou o valor de TEL nos testemunhos estudados. Zn e Hg mostraram enriquecimentos pontuais em diferentes seções do testemunho T3. Com relação aos ETR, houve novamente a observação de enriquecimento causado por minerais pesados, e os teores modelados parecem refletir níveis naturais para estes elementos nos quatro testemunhos. Tais informações podem ser utilizadas na ampliação do uso de ferramentas biogeoquímicas de avaliação e prevenção de riscos aos quais o sistema estudado está sujeito, e na tomada de decisão pelo poder público no sentido da conservação ambiental da região. / The estuary-lagoon complex of Cananéia-Iguape, in the southern portion of the coast of São Paulo state, is part of an important environmental reserve and an extremely productive coastal ecosystem. The region encloses the Valo Grande channel, built more than 160 years ago, which favors the introduction of fresh water from Ribeira de Iguape river directly into the estuarine system contributing to important biogeochemical changes in the region. Through this channel, many nutrients arrive at the estuary, as well as, metals and other slightly soluble elements, that end up as sediments. In this research, samples of the water column and surface sediments were collected in the estuary-lagoon complex of Cananéia-Iguape and contiguous environments, as well as, sediment profiles in the south of the estuary, considered to be the most conserved region. The main objective of this study was to evaluate the processes that govern the distribution of rare earth elements (REE) in the sediments of the system, associating and comparing them to other elements, both essential and toxic, using fractionation patterns, anomalies and the geochemical signature of minerals that act in the distribution of REE to evaluate the origin and interpret natural levels and the amplitude of possible anthropic effects to which the Complex is submitted. The results show that the hydrochemical characteristics in the northern region of the complex are strongly influenced by the provision of fresh water through Valo Grande channel and its resulting biogeochemical processes, while the southern region is more conserved, showing the natural biogeochemical balance of estuarine systems, offering greater support to primary production. The elemental concentrations of Al, As, Ba, Ca, Cd, Co, Cr, Cs, Fe, Hg, Hf, P, Pb, Rb, Sb, Sc, Th, U, Zn, Zr and REE* in the surface sediments, show distribution related to depositional/textural characteristics, in such a way most of these elements presented their highest concentrations in regions of recognized low hydrodynamic energy, in the Ribeira de Iguape river and Mar Pequeno region. A comparison of the values obtained for As, Cd, Pb, Cr, Hg and Zn with the Canadian sediment quality guidelines (TEL and PEL) shows that none of the evaluated elements reached concentrations indicating a frequent occurrence of negative effects on aquatic organisms (PEL), however, As, Cr, Pb and Zn have sometimes exceeded concentration values indicating a low probability of occurrence of adverse effects on biota (TEL). Enrichment factors calculated in relation to the upper continental crust (FEUCC) and the regional geochemical background (FEBG) pointed out regions where Pb, P and Sb accumulated above the levels considered natural, however have shown that the high values of As and Cr are related to a natural enrichment of the sediments in the region. For the REE, FEUCC and FEBG indicated enrichment in the sea region adjacent to the estuary and at stations in Ribeira de Iguape river and Valo Grande. Data modeling through linear multiple regression showed that the values, which would normally be considered anomalous, are natural and reflect the presence of heavy minerals at these sites. Other elements that appear to be naturally enriched where there is the indication of occurrence of such minerals are As, Ca, Cr, Th, U, in addition to the signaling elements Hf and Zr. Ce anomalies showed a possible relationship with biologically mediated Ce+3 to Ce+4 oxidation processes in the most productive areas of the estuary. Out of the four sediment profiles obtained in the southern region of the estuary, three showed sections with FEUCC and FEBG values for Pb suggesting anthropogenic contribution. Such values decrease towards the south of the system, however showed a small time variation. None of the obtained Pb values overcame the values of TEL for such sediment profiles. Zn and Hg showed one-off enrichments in different sections of T3 sediment core. Regarding REE, there was again the observation of enrichment caused by heavy minerals in one of the sediment cores, and the modeled contents seem to reflect natural levels for these elements in the four cores. Such information can be used in the expansion of the biogeochemical tools for assessment and prevention of the risks to which the studied system is subject and in the decision making by the public sector towards the environmental preservation of the region.

No presente trabalho são descritas as etapas de desenvolvimento e implantação das rotinas analíticas utilizando ICP-OES e ICP-MS para a determinação de elementos terras raras em materiais geológicos. A implantação inclui determinações comparativas de vários granitóides dos maciços ou complexos Ibiúna-Piedade, SP, e Cunhaporanga, PR, já previamente analisados por meio de ICP-MS e INAA (Universidade Kansas, em Lawrence, USA). Através de uma pequena modificação no método inicial, os limites de detecção para a análise dos ETR por ICP-OES foram melhorados para concentrações próximas à 10 vezes o condrito. Porém para a análise de ETR em materiais geológicos com valores inferiores a estes é necessária a utilização de uma técnica mais sensível como o ICP-MS. A técnica ICP-MS não é livre de problemas sendo necessárias correções de interferências moleculares e drift instrumental para a obtenção de resultados com precisão e exatidão adequados. Realizou-se a etapa de validação do método utilizando materiais de referência internacionais geológicos. A análise estatística dos resultados obtidos utilizando três métodos de abertura de amostra (ataque ácido em forno de microondas, em bombas tipo Parr e fusão alcalina) mostrou a possibilidade de utilização do ataque ácido em forno de microondas e da fusão alcalina com posterior separação cromatográfica como alternativas eficientes para a determinação de ETR apesar da baixa eficiência nas recuperações dos elementos Zr e Hf em rochas ácidas e gnáissicas equivalentes. / The steps for the development of the analytical routines leading to the determination of the rare earth elements (REE) with the use of ICP-AES and ICP-MS techniques are discussed in this contribution. The set-up of these routines was also evaluated with determinations of REE in several granitoid rocks from the Piedade-Ibiuna (SP) and Cunhaporanga (PR) complexes, and the results compared with those obtained in other laboratories (University of Kansas, Lawrence) with ICP-MS and INAA. The work previously performed for the adaptation of REE determination with ICPAES was reviewed, allowing analyses to be realized with better results for concentrations close to 10 times the chondrite value. At lower concentrations, REE analysis have to be performed with ICP-MS. The ICP-MS technique shows much better accuracy and precision than ICPAES, but presents problems of its own. Instrumental drift corrections, as well as corrections due to molecular interferences, are mandatory. Evaluation of the successfully adapted routines was realized analyzing international reference materials several times and applying statistical tests. A comparison of results with three dissolution techniques (acid attack in microwave oven, use of Parr type bombs, and alkaline fusion with borates) showed that both acid attack and alkaline fusion with later chromatographic separation are rather efficient alternatives for the determination of REE, although Zr and Hf are not fully recovered in many acid igneous and equivalent gneissic rocks.

O excessivo processo de urbanização da Região Metropolitana de São Paulo resultou na perda das características naturais dos seus cursos d\'água ocasionando profundas alterações nos regimes de vazão e de qualidade. O objetivo desse estudo foi avaliar a concentração de metais tóxicos, os semi-metais As, Sb e Se e os elementos terras raras, presentes em amostras de sedimento superficiais coletadas nos Reservatórios Billings, Guarapiranga e Rio Grande. Os elementos Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se e Zn foram determinados pela técnica de Espectrometria de Emissão Ótica com Plasma Indutivamente Acoplado (ICP OES). Alguns elementos maiores, traço e elementos terras raras (Ce, Eu, La, Lu, Nd, Sm, Tb e Yb) foram determinados pela técnica de Análise por Ativação Neutrônica Instrumental (INAA). A concentração de Hg total foi determinada pela técnica Espectrometria de Absorção Atômica com Geração de Vapor Frio (CVAAS). A validação das metodologias foi realizada por meio da análise de materiais de referência certificados. Para avaliar as possíveis fontes de contaminação antrópicas foram utilizadas as ferramentas de fator de enriquecimento (FE) e o índice de geoacumulação (IGeo). Os resultados obtidos pelas técnicas foram comparados com os valores orientadores TEL e PEL estabelecidos pelo CCME (Canadian Council of Ministers of the Environment) e adotados pela CETESB. Todos os pontos analisados apresentaram valores > TEL para todos os metais e dois pontos da represa Billings (BILL02100 e 02030), valores > PEL para As, Cr, Cu, Hg, Ni, Pb e Zn, provavelmente em decorrência do recebimento das águas do Rio Pinheiros e das bacias de drenagem do ribeirão Cocaia e Bororé. Os valores de FE e IGeo calculados apontaram possíveis contaminações antrópicas para Sb e Se para os elementos determinados por ICP OES e de As, Cr, Sb e Zn, por INAA. O reservatório Billings apresentou, em geral, as maiores concentrações para os elementos analisados, indicando uma má qualidade de seus sedimentos. Este estudo confirma a necessidade de um monitoramento frequente da qualidade do sedimento nos reservatórios estudados como procedimento indispensável para avaliação periódica da qualidade das bacias, considerando sua importância no fornecimento de água para a Região Metropolitana de São Paulo. / The excessive urbanization process of the São Paulo Metropolitan Region resulted in the loss of the natural characteristics of its watercourses causing serious changes in flow and quality regimes. The objective of this study was evaluate the concentration of toxic metals, semi metals As, Sb and Se, and rare earth elements present in surface sediment samples collected at the Billings, Guarapiranga and Rio Grande Reservoirs. The Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se and Zn elements were analyzed using Optical Emission Spectrometry With Inductively Coupled Plasma (ICP OES). Some major, trace and rare earth elements (Ce, Eu, La, Lu, Nd, Sm, Tb and Yb) were analyzed by the Instrumental Neutron Activation Analysis (INAA) technique. The total Hg concentration was determined by Cold Vapor Atomic Absorption Spectrometry technique (CVAAS). The validation of the methodologies was performed by means of the certified reference material analyses. To assess the sources of anthropogenic contamination, the enrichment factor (EF) and the geoacumulation index (IGeo) were calculated. The results obtained for both techniques were compared with TEL and PEL oriented values established by CCME (Canadian Council of Ministers of the Environment) and adopted by CETESB (Environmental Company of the Sao Paulo State). All sampling points showed concentration values for toxic metals >TEL and 2 points at Billings Reservoir (BILL02030 and 02100), values > PEL for As, Cr, Cu, Hg, Ni, Pb and Zn, probably due to the entrance of the Pinheiros River waters and drainage basins of the Cocaia and Bororé streams. The calculated EF and IGeo values indicated possible anthropogenic contamination for Sb and Se for the elements determined by ICP OES and As, Cr, Sb and Zn, obtained by INAA. The Billings reservoir presented, in general, the highest concentrations for the analyzed elements, indicating a poor quality of its sediments. This study confirms the need of a frequent monitoring of the sediment quality in the studied reservoirs as an indispensable procedure for periodic evaluation of the basin quality, considering its importance in the water supply for the Metropolitan Region of São Paulo.

Os pegmatitos estudados estão associados à fácies albita granito do granito Madeira, a qual corresponde ao depósito de Sn-Nb-Ta (F, ETR, U, Th) Madeira, na mina Pitinga (AM) e estão associados a falhas de orientação N320/60SW. Estas rochas contêm minerais poucos comuns como gagarinita (NaCaYF6), genthelvita (Zn4Be3(SiO4)3S) e polilitionita (KLi2AlSi4O10(F, OH)2), além de grandes quantidades de criolita (Na3AlF6). Com base na composição química e mineralógica, estes pegmatitos foram classificados em três tipos: PEG ANF (teores médios de K e Na, com alta concentração de anfibólios), PEG POL (rico em K e com alta concentração de polilitionita) e PEG CRIO (rico em Na e com alta concentração de criolita). Estes pegmatitos contêm altos teores de ETR (especialmente ETRP) e Y, que estão concentrados principalmente na xenotima e na gagarinita. Estes elementos também ocorrem em elevados teores na grande parte dos demais minerais analisados. Também se destacam as concentrações anômalas de F, muito superiores às detectadas nos pegmatitos de outras localidades, e que promoveram o enriquecimento em Li, Na, K, Rb e Cs. A similaridade na composição química do AGN com os pegmatitos indica que eles possuem a mesma fonte. / The pegmatites studied are associated with the albite granite facies of the Madeira granite, which corresponds to the Sn-Nb-Ta (F, ETR, U, Th) Madeira deposit at the Pitinga mine (AM). They are associated with N320/60SW orientation faults. These rocks contain few common minerals such as gagarinite (NaCaYF6), genthelvite (Zn4Be3(SiO4)3S) and polylithionite (KLi2AlSi4O10(F,OH)2), as well as large amounts of cryolite (Na3AlF6). Based on the chemical and mineralogical composition, these pegmatites were classified into three groups: PEG ANF (medium K and Na, with high concentration of amphiboles), PEG POL (K rich and with high polylithionite concentration) and PEG CRIO (rich in Na and with high concentration of cryolite). These pegmatites contain high levels of REE (especially HREE) and Y, which are mainly concentrated in xenotime and gagarinite. These elements also occur at high levels in most of the other minerals analyzed. Anomalous concentrations of F, much higher than those detected in pegmatites from other localities, were also highlighted, and promoted enrichment in Li, Na, K, Rb and Cs. The similarity in the chemical composition of AGN with pegmatites indicates that they have the same source.

Rare earth elements (REE) are considered as critical and non-substitutable metals for electronics and green technology. A greater diversity of supply is needed and the REE occur in a wide range of REE- and REE-bearing minerals within different ore deposit types. The beneficiation processes for REE ores can vary widely based on their mineralogy and texture. It is, therefore, essential to understand the mineralogical characteristics when designing processing routes. Little research was carried out on this topic until the last few years, apart from bastnäsite, monazite, and xenotime, and most REE minerals in deposits currently under exploration are poorly understood in terms of processing characteristics. This geometallurgical study brings together the results of process mineralogy and minerals processing to recover synchysite-(Ce) and apatite from the carbonatite at Songwe Hill, Malawi. This deposit is unusual because it is a potential carbonatite source of both LREE and HREE. Results from previous flowsheet development studies on this deposit suggest that flotation is the most promising processing route and therefore this study concentrated on testing this hypothesis. It sought to understand the mineralogy better in order to predict processing response and carried out a series of flotation experiments to improve the processing efficiency. It also investigated the fundamental magnetic properties of the rare earth fluorcarbonate minerals (including synchysite) and established for the first time that there is a systematic variation in their properties that can be applied to minerals processing. Eight samples of REE carbonatite drill core, crushed to 1700 μm, and a composite sample ground to 53 μm and 38 μm were used throughout this research. Automated mineralogy (QEMSCAN®) was applied to determine the mineralogical characteristics of the ore deposit. This utilised a novel species identification protocol (SIP) for REE minerals in carbonatites, which was validated by electron microscopy (SEM-EDS), and electron probe microanalysis (EPMA). The principal REE minerals at Songwe are the REE fluorcarbonates, synchysite-(Ce) and also parisite-(Ce). These are challenging minerals for automated mineralogical techniques owing to their chemical similarity and common occurrence either as bladed (needle-like) crystals, which is the main textural type at Songwe Hill, or as syntaxial intergrowths. However, using the SIP developed in this study, the QEMSCAN® can distinguish between these minerals based on the Ca content and can also recognise syntaxial intergrowths on a scale of about > 20 μm. The Songwe Hill carbonatite hosts about 6 wt% to 10 wt% of REE- and REE-bearing minerals. Apatite hosts the more valuable HREE in addition to P2O5, followed by synchysite-(Ce)/parisite-(Ce) (mainly synchysite-(Ce)), and minor florencite-(Ce), which host the LREE. These minerals are commonly associated with the predominant gangue minerals, ankerite and calcite, and, to a lesser extent Fe- Ox/CO3 and K-feldspar, strontianite and baryte. Fundamental magnetic properties of pure REE fluorcarbonate single crystal minerals using a vibrating sample magnetometer (VSM) were determined. The magnetic susceptibility is highly dependent on the mineral composition. It is positive (paramagnetic) for bastnäsite-(Ce) and gradually decreases as the amount of Ca increases in parisite-(Ce), becoming negative (diamagnetic) for the Ca-rich member of the series, röntgenite. Synchysite-(Ce) in this deposit was experimentally determined by magnetic separation and behaved as a diamagnetic mineral. This can be explained by the layered structure common to the REE fluorcarbonate series minerals. Selected laboratory scale mineral processing experiments including magnetic separation and froth flotation were performed. Pre-concentration tests by magnetic separation showed a recovery of 84% for P2O5, 80% for Y2O3, and 76% for Ce2O3 in the non-magnetic product, with gangue minerals rejection of about 49% for ankerite and 48% for Fe-Ox/CO3 to the magnetic product. Apatite and synchysite-(Ce) loss to the magnetic product is mainly the result of their association with the paramagnetic minerals i.e. ankerite and Fe-Ox/CO3 as indicated by automated mineralogy. A spectrophotometer was utilised to measure the solubility of the organic chemical reagents including fatty acids and lignin sulphonate in different alkaline solutions and to determine the appropriate operating parameters for bench flotation tests. The results indicated that the solubility of fatty acids increased with increasing the pH value from 8.5 to 10.5, while the opposite was observed for lignin sulphonate. 35 bench-scale froth flotation tests under a wide range of chemical and operating conditions including pH modifiers and dosages, soluble and insoluble collectors, depressants, temperature, and conditioning time were performed. The results demonstrated that fatty acids and lignin sulphonate are sensitive to changes in pH, conditioning time, and temperature. These factors significantly affected flotation efficiency. A recovery of 86% for P2O5 and 74% for both of Y2O3 and Ce2O3 with TREO upgrading from 1.6 wt% to 3.8 wt% at a mass pull of 31% were achieved under a constant pulp pH of 9.5, elevated temperature, and long conditioning time. This study suggests that combining magnetic separation and froth flotation techniques to pre-concentrate and upgrade the REE- and REE-bearing minerals, should be considered further to minimise the cost of the chemical reagents used in froth flotation and gangue leaching.