O objetivo deste trabalho é a extração de Au, Ag, Cu e Zn a partir de dois tipos de lodos galvânicos utilizando um processo híbrido de sulfatação seletiva e lixiviação com tiossulfato de sódio e amônio. Nos experimentos realizados, o lodo galvânico foi misturado com um agente promotor de sulfato (enxofre, sulfato de ferro ou pirita) e foi tratado por processos pirometalúrgicos a temperaturas até 750◦C. Nesta fase, este agente sulfatante é oxidado térmicamente, transformando a atmosfera do forno e os óxidos metálicos em sulfatos solúveis em água. Depois disso, os sulfatos foram tratados por lixiviação com água para a recuperação de Ag, Cu, Ni e Zn. Como o ouro não forma sulfatos nesta reação, foi realizada uma segunda fase de lixiviação utilizando tiossulfato de sódio e de amônio, reagentes eficazes e menos prejudiciais ao ambiente do que o cianeto. Diferentes parâmetros foram analisados como qual agente promotor de sulfatação apresentou a maior recuperação de metais em solução, a proporção ótima lodo galvânico/ agente sulfatação, a temperatura de forno, o tempo de aquecimento no forno e o tempo de lixiviação. Além disso, uma comparação da recuperação de ouro com cianeto e tiossulfato de sódio e de amônio foi realizada. A configuração que demonstrou a melhor recuperação de metal em solução tinha uma proporção de 1: 0,4 de lodo galvânico/enxofre, uma temperatura de forno de 550◦C, um tempo de aquecimento de 90 minutos e um tempo de lixiviação em água de 15 minutos. Usando estes parâmetros, as taxas de recuperação de 75% de prata, 68% de cobre, 52% de Ni e 67% de Zn foram obtidas. A lixiviação de tiossulfato de sódio resultou em uma recuperação de 78% do Au, próximos aos valores obtidos utilizando cianeto. / The purpose of this work is the selective extraction of Au, Ag, Cu and Zn from two types of galvanic sludge using a mixed process of sulfate roasting and sodium thiosulfate and ammonium thiosulfate leaching. In the experiments, the sludge was mixed with a sulfate promoter (sulfur, iron sulfate or pyrite) and treated by pyrometallurgical processes at temperatures up to 750◦C. At this stage, this agent is thermally oxidized, turning the furnace atmosphere and the metallic oxides into water-soluble sulfates. Afterward, the sulfates can be treated by leaching with water for recovery of Ag, Cu, Ni and Zn. The gold does not form sulfates in this reaction and was recovered through a second leaching stage using sodium and ammonium thiosulfate, an effective reagent and less harmful to the environment than cyanide. Different parameters as the sulfate promoter that achieves the highest recovery of metals, the proportion of galvanic sludge to sulfating agent, the temperature, the heating time in the oven and the leaching time were evaluated. Additionally, a comparison of gold recovery using cyanide versus sodium and ammonium thiosulfate was performed. The configuration that showed the best metal recovery included a 1:0.4 ratio of sludge to sulfur, an oven temperature of 550◦C, a roasting time of 90 minutes and a water leaching time of 15 minutes. Using these parameters, recovery rates of 75 % of the silver, 68% of the copper, 52% of Ni and 67% of the Zn were obtained. The sodium thiosulfate leaching resulted in a recovery of 78% of the Au, close to the values obtained using cyanide.

Orientador: Flávio Luis Schmidt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-16T15:12:47Z (GMT). No. of bitstreams: 1 Martins_BrunodeAndrade_D.pdf: 17768602 bytes, checksum: d9a4daf666aa8a8349c5b37f0a160fe1 (MD5) Previous issue date: 2010 / Doutorado / Doutor em Tecnologia de Alimentos

[pt] A cinética da carbocloração do pentóxido de vanádio (V2O5) puro, pelo tratamento com gás cloro, de misturas sob a forma de pó, não-compactadas, de V2O5 e grafite (agente redutor), foi investigada, com o emprego do método termogravimétrico, no intervalo de 350 a 550°C, sendo estudada a influência, sobre a velocidade de reação, das seguintes variáveis: temperatura de cloração, percentagem de agente redutor na amostra inicial e pressão parcial do cloro. Na avaliação do efeito da temperatura de cloração sobre a cinética da reação, o Modelo do Núcleo Não Reagido foi utilizado para interpretar os resultados experimentais obtidos. O valor calculado para a energia de ativação da reação foi de 52 kJ, na faixa de 350 a 400°C, sugerindo a reação química como a etapa controladora do processo, e de 12 kJ, na faixa de 400 a 550°C, caso em que a difusão do gás reagente (condições fluidodinâmicas) poderia ser o mecanismo controlador. O efeito da percentagem de carbono, no intervalo de 17 a 30%, nas temperaturas de 350 e 500°C, revelou comportamentos distintos da reação, sugerindo a predominância, conforme o caso estudado, de fatores diferentes, tais como o contato sólido-sólido, atuando para aumentar a taxa de reação, e o excesso estequiométrico de carbono ou a dificuldade de penetração do gás reagente, concorrendo para diminuir a taxa de reação. A reação investigada caracterizou-se por ser aproximadamente de segunda ordem em relação ao cloro, à temperatura de 350°C, e, de primeira ordem, a 500°C. / [en] The kinetics of the carbochlorination of pure vanadium pentoxide (V2O5) by the treatment of a powdered mixture of V2O5 and graphite with chlorine gas, was investigated, using the termogravimetric method, in the temperature range of 350°C to 550°C. The effect of chlorination temperature, amount of reducing agent (graphite) and partial pressure of chlorine gas on the reation kinetics was studied. Regarding the influence of temperature on the reaction kinetics, the shrinking-core or topochemical model was used to explain the experimental results obtained during this study. The activation energy of the reaction, in the temperature range of 350 to 400°C, was 52 kJ, suggesting the chemical reaction as the rate controlling step, and, in the temperature range of 400 to 550°C, was 11 kJ, as the diffusion of the reacting gas (fluid-dynamic conditions) seems to be the limiting step. The effect of the amount of graphite, in the range of 17 to 30%, at the temperatures of 350°C and 500°C, leads to distinct reaction behaviors, distinguishing the predominance of different factors according to the case studied, such as the contact between the reacting solids, which acts in order to increase the reaction rate, and the excess of carbon amount or the difficult of penetration of the reacting gas, acting towards a reduction of the reaction rate. The reaction occurred to be about second-order with respect to Cl2, at the temperature of 350°C, and first-order, at 500°C.

Abstract Zinc production has been known since 200 BC. Fluidised bed roasting is the first process stage of the electrolytical zinc production process, was developed in the 1940s. The raw material for zinc is usually sphalerite concentrate. This sulphide concentrate is oxidised in a roaster. Oxidation reactions produce energy, which is removed as steam, and sulphur dioxide, which is used as the raw material of sulphuric acid. During recent decades sphalerite concentrates have contained more and more impurities and at the same time they have become more fine-grained. Impurities cause problems during fluidised bed roasting. As a consequence, production capacity decreases, there are breaks in production. Starting up and shutting down a process during production breaks cause the environmental emissions. In order to be able optimise production, the oxidation mechanisms of impure sphalerite and methods for controlling them have to be known. The hypothesis of this work was as follows: In addition to temperature, the impurity content and particle size of the feed and oxygen coefficient also have an effect on the stability of fluidised bed roasting. Diverse concentrates require different oxygen coefficients and temperatures. The basic target of this work was to develop a method to help find the required conditions and to control them in industrial roasters. This study was restricted to considering the effects of the iron, copper and lead contents in sphalerite concentrate. A review was made of earlier roasting studies and experiences. This study also evaluated the thermodynamic background of roasting. The oxidation mechanisms were also studied in the laboratory using a fluidised bed roaster and horizontal tube furnace. The results were validated in an industrial roaster. On the grounds of these studies the different sphalerite concentrates really do require diverse roasting temperatures and oxygen coefficients. Foremore, the same kinds of concentrates require a different roasting temperature and oxygen coefficient, if their particle size distributions are different. Controlling the concentrate feed particle size may help to control the stability of the roasting bed and the temperature of the upper part of the furnace. The impurities increase the forming of direct bond sintering and thus the forming of sulphide liquid phases. Oxides and sulphates may also form liquid phases. These kinds of liquid phases cause problems in the fluidised bed. Continuous control of the oxygen coefficient and bed temperature and the use of a unique oxygen coefficient and temperature range for every concentrate mixture would make it possible to minimise problems in the furnace. Laboratory and industrial scale tests have verified the variables and methods for controlling conditions in the roaster bed. / Tiivistelmä Sinkin valmistus on ollut tunnettua ajalta 200 eKr. Leijukerrospasutus, joka on ensimmäinen prosessivaihe elektrolyyttisessä sinkin valmistusprosessissa, otettiin sekin käyttöön jo 1940-luvulla. Sinkin raaka-aineena käytetään sfaleriittirikastetta, joka hapetetaan pasutuksessa. Hapetusreaktiot tuottavat energiaa, joka otetaan talteen höyrynä, ja rikkidioksidia, josta tuotetaan rikkihappoa. Viime vuosikymmeninä sfaleriittirikasteet ovat tulleet epäpuhtaammiksi ja samalla partikkelikooltaan hienommiksi. Epäpuhtaudet aiheuttavat ongelmia leijupetiin. Tämän seurauksena uunien kapasiteetti laskee, tulee tuotannon seisauksia. Näiden seisauksien yhteydessä tapahtuvat prosessin ylös- ja alasajot aiheuttavat päästöjä. Tuotannon optimoimiseksi täytyy tuntea epäpuhtaiden sfaleriittirikasteiden hapetusmekanismit ja tavat niiden hallitsemiseksi. Tämän työn hypoteesi oli: Leijukerrospasutuksen stabiilisuuteen vaikuttaa lämpötilan lisäksi epäpuhtauksien määrä syötteessä ja syötteen partikkelikokojakauma sekä happikerroin. Erilaiset rikasteet vaativat erilaisen happikerroin- ja lämpötila-alueen. Työn tavoite oli kehittää menetelmä,jolla saadaan vaaditut olosuhteet syntymään ja hallittua. Tutkimuksissa rajoituttiin tarkastelemaan sfaleriittirikasteiden sisältämän raudan, kuparin ja lyijyn vaikutusta. Työssä tutustuttiin epäpuhtaiden sfaleriittirikasteiden pasutuksen alueelta aiemmin tehtyihin tutkimuksiin ja eri pasutoilla saatuihin kokemuksiin sekä selvitettiin pasutuksen termodynaaminen tausta. Laboratoriotutkimuksilla selvitettiin hapettumismekanismeja leijukerrosreaktorissa ja pelleteillä kvartsilaivassa putkiuunissa. Tulosten todentaminen tehtiin koeajoilla teollisessa tuotantolaitoksessa. Johtopäätöksenä näistä tutkimuksista voidaan todeta, että erilaiset sfaleriittirikasteet edellyttävät kullekin rikasteelle ominaista pasutuslämpötilaa ja happikerrointa. Lisäksi samantyyppistenkin rikasteiden vaatima pasutuslämpötila ja happikerroin voivat vaihdella, jos rikasteen partikkelikokojakauma vaihtelee. Syötteen partikkelikokoa säätäen voidaan ohjata pedin stabiilisuutta ja uunin yläosan lämpötilaa. Epäpuhtaudet lisäävät suorasidossintrautumien syntyä ja siten sulfidisulafaasien muodostumista. Sulafaaseja voivat muodostaa myös tietyt oksidit ja sulfaatit. Tästä seuraa ongelmia leijupedissä. Happikertoimen jatkuva seuranta ja säätö kullekin rikasteelle ominaisella alueella, samoin kuin lämpötilan seuranta ja säätö, mahdollistavat ongelmien minimoinnin. Tähän työhön liittyvissä laboratoriotutkimuksissa ja teollisen mittakaavan tutkimuksissa todennettiin muuttujat ja keinot olosuhteiden hallitsemiseksi.

[pt] Os concentrados de sulfetos minerais são importantes fontes de matériaprima para extração de metais não-ferrosos. O presente trabalho tem por objetivo avaliar o processamento químico de um concentrado de calcopirita com um teor de cobre relativamente baixo, que o inviabiliza de ser utilizado nos processos metalúrgicos estabelecidos (ustulação / fusão mática / conversão / refino). A motivação para tal tem origem em uma parceria com uma empresa do setor de produtos químicos com interesse na obtenção seletiva de CuSO4 e Fe2O3 a partir de um concentrado com esta característica. Para atender a esse objetivo, foi inicialmente conduzido um estudo de fundamentação teórica (termodinâmico) tendo em vista identificar a viabilidade da seletividade desejada, seguido de uma apreciação do comportamento termoquímico desse sistema reacional. O estudo experimental foi realizado através da avaliação do efeito de variáveis relevantes, tais como temperatura e composição química da atmosfera reacional, e um estudo cinético. A matéria-prima e os produtos obtidos foram caracterizados através de Difração de Raios-X, Microscopia Eletrônica de Varredura e Espectroscopia de Raios-X por Dispersão de Energia. Por fim, foram realizados testes de solubilização em água de amostras selecionadas dos produtos da ustulação a fim de se constatar, de forma prática, a conversão seletiva da calcopirita em CuSO4 e Fe2O3. Tal fato pôde ser observado através da formação de um licor azulado, típico do sulfato de cobre, e um resíduo sólido acastanhado desprovido de Cu, conforme verificado pelos métodos de caracterização. / [en] The sulphide minerals concentrates are an important source of raw material in extractive processes of nonferrous metals. This study aims to evaluate the chemical processing of a chalcopyrite concentrate with a relatively low copper content. The motivation for the research comes from a partnership with a chemicals production company with interest in obtaining, selectively, CuSO4 and Fe2O3 from this kind of concentrate. For the purpose of meet this objective, it was performed a thermodynamic study, as well as an appreciation of the thermochemical behavior of the reaction system, in order to identify the conditions under which the mentioned selectivity could be fulfilled. Thereafter, it was conducted an experimental study evaluating variables such as temperature and chemical composition of the atmosphere over the reaction time. The obtained products as well as the raw materials were characterized using X-Ray Diffraction, Scanning Electron Microscopy and X-Ray Spectroscopy Energy Dispersive. Finally, some water-solubilizing tests were performed on selected roasted products samples in order to verify, in practice, the selective conversion of chalcopyrite into CuSO4 and Fe2O3. Such fact could be observed through the formation of a blue liquor, typical copper sulfate, and a brown solid residue deprived of Cu, as verified by the characterization methods.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19019号 / 農博第2097号 / 新制||農||1029(附属図書館) / 学位論文||H27||N4901(農学部図書室) / 31970 / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 近藤 直, 教授 清水 浩, 准教授 小川 雄一 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

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Peanuts are grown around the world and in United States where most peanuts are consumed after roasting. Peanuts are roasted to a specified color on L*a*b* scale as it is correlated with quality and acceptability. Two batches of Virginia type peanuts were acquired, one normal and other a high oleic variety. A surface response model using the Box-Behnken design was developed for Behmor 2000AB and GeneCafe coffee roasters, for normal and high oleic peanuts respectively with sample size, roast time and power/temperature as dependent variables and L* as a response variable. The model for Behmor was not significant (p>0.05 and R2 =0.87) but with effect contribution of roast time while the GeneCafe model was significant (p<0.05 and R2=0.98) with multiple first and second order effect contributions from temperature and roast time. Each model was validated and Behmor was found to be more consistent and predictable compared to GeneCafe. Both varieties of peanuts were roasted on each roaster and tested for volatile analysis using SPME GC/MS with high variation observed within samples which may be caused by uneven roasting. The volatile results showed similar trends for seventeen compounds between normal and high oleic samples. The Behmor roaster was more effective at predictable roasting for 50 to 100 g sample and more validation is needed on GeneCafe to improve its model. The results can help with quality testing of new varieties of Virginia type peanuts quickly without relying on large sample size typically used in other lab scale studies. / Master of Science in Life Sciences / Peanuts are grown around the world and in United States where most of it is consumed as a confection. They are roasted to a specified color on scale as it is correlated with quality and optimization. We wanted to develop a method of small-scale peanut roasting that allows peanut breeders to roast and evaluate quality of small samples of peanuts. We used an optimization method to test two different coffee roasters for peanut roasting (Behmor and GeneCafe roasters), with normal and high oleic peanuts. Behmor was more sensitive to changes in roast time while GeneCafe was more sensitive to temperature, roast time and combined effects. The models were validated on each machine and Behmor was found to be more consistent and predictable compared to GeneCafe. Peanuts were roasted on each roaster and tested for aroma compounds. The aroma compounds were similar between normal and high oleic samples. The Behmor roaster was more effective at predictable roasting of peanuts with sample size ranging from 50 to 100 g. Our results allow us to predictably roast very small lots of peanuts to support determination of flavor quality for peanut breeding research.