Submitted by Cássio da Cruz Nogueira (cassionogueirakk@gmail.com) on 2017-02-13T14:57:58Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_AvaliacaoPotencialBiotecnologico.pdf: 2998358 bytes, checksum: 8f3a932c518a34e03b009f67d86b48bc (MD5) / Approved for entry into archive by Edisangela Bastos (edisangela@ufpa.br) on 2017-02-15T15:18:42Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_AvaliacaoPotencialBiotecnologico.pdf: 2998358 bytes, checksum: 8f3a932c518a34e03b009f67d86b48bc (MD5) / Made available in DSpace on 2017-02-15T15:18:42Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertacao_AvaliacaoPotencialBiotecnologico.pdf: 2998358 bytes, checksum: 8f3a932c518a34e03b009f67d86b48bc (MD5) Previous issue date: 2016-04-08 / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / A bioxidação é um dos pré-tratamentos utilizados antes da cianetação convencional para promover a solubilização de metais como cobre, ferro através da ação oxidante de micro-organismos nos sulfetos metálicos. Esta técnica consolidada é utilizada antes do processo de cianetação para reduzir o consumo de cianeto livre e tornar o ouro acessível aos processos posteriores de recuperação, elevando significativamente a extração deste metal. Desta forma, o presente trabalho consiste em estudar a melhor rota biotecnológica para o pré-tratamento de um minério aurífero e o efeito destes tratamento na avaliação do consumo de cianeto durante a cianetação . Para este fim, testes de bioxidação foram conduzidos em escala de laboratório utilizando um minério aurífero (90g/ton Au) proveniente de uma mina situada no Estado do Amapá, Brasil. As culturas bacterianas utilizadas nos testes biológicos de 20 dias foram Acidithiobacillus ferrooxidans, linhagem LR e Acidithiobacillus thiooxidans, linhagem FG01. Os produtos do processo de bioxidação foram submetidos a ensaios de cianetação para testes de avaliação de consumo de cianeto e recuperação de ouro. Os estudos experimentais realizados mostraram que após 24h de cianetação da amostra mineral sem tratamento a recuperação de ouro foi de 93% (32 mg/L) com o consumo de NaCN de 2,86 kg.t-1, enquanto a melhor extração entre as amostras bioxidadas foi a do biorreator R2 de condição oxidante com 87% (30 mg/L) de ouro, e com consumo de 2,64 kg.t-1 de NaCN. Os resultados obtidos mostram a viabilidade da técnica de bioxidação antes da cianetação para a redução no consumo de cianeto. / One of the most commonly used pre-treatments prior conventional cyanidation is the biooxidation. This technical is a biological process capable of promote solubilization of metals such as copper, iron through the oxidative action of microorganisms in metal sulfides and it is applied as a pretreatment in the cyanidation process to reduce free cyanide consumption making this a feasible and economic process. Thus, the aim of this work was to study the best biotechnology route for the pretreatment of the gold ore in order to reduce cyanide consumption during the convencional cyanidation and increasing the gold recovery. For this purpose, biological tests has been investigated at laboratory scale on a gold ore sample coming from Estado do Amapá, Brazil (90 g/ton). Bacterial cultures utilised in the biological tests of 20 days consisted of Acidithiobacillus ferrooxidans-LRe Acidithiobacillus thiooxidans-LR. The biooxidated samples were submitted to cyanidation tests for gold recovery and tests of consumption of cyanide. Experimental studies demonstrate that after 24h leaching time by direct cyanidation, the gold recovery was 93% (32 mg/L) with a cyanide consumption of 2,84 kg.t-1, while the best gold extraction between biooxidated samples was from bioreactor R2 with 87% (30 mg/L), and the cyanide consumption of 2,64 kg.t-1. Experimental results have shown the technical feasibility of the biooxidative prior to convencional leaching for for reducing the consumption of reagent cyanide.

Dans un premier temps, nous avons synthétisé et caractérisé une chondrite à enstatite reconstituée. En étudiant cet objet, nous avons pu identifier et comprendre le signal Raman des sulfures présents dans les météorites à enstatite. La réponse Raman de ces phases est obtenue via l'activation des modes infra-rouge suite à une modification de la symétrie dans le réseau cristallin. Dans un second temps, nous avons utilise cet analogue pour comprendre le processus de bio-alteration des chondrites à enstatite dans les conditions terrestres actuelles, donc en aérobiose. Afin de bien comprendre ce phénomène de bio altération sur ce matériau complexe, il a été indispensable d'étudier ce mécanisme sur chacune des phases présentes dans celui-ci. Ainsi l'analogue de chondrite à enstatite, l'enstatite, la troilite, l'alliage Fe-Si et aussi de l'olivine ont été altérés abiotiquement et bio altérés par les souches Acidithiobacillus ferrooxidans et Acidithiobacillus thiooxidans, ¨¤ pH ¡Ö 2 ¨¤ T = 20¡ãC. Cette étude a permis d'obtenir et d'interpréter à l'échelle de la microscopie électronique à balayage les principales phases et microstructures qui se développent lors de l'altération abiotique ou biologique d'une chondrite à enstatite. En parallèle, des mesures régulières de la chimie du milieu aqueux ont permis d'étudier la cinétique de lixiviation de ces expériences de bio-alteration et de la comparer à une modélisation thermodynamique et cinétique, que nous avons effectué avec le programme Jchess. Nos résultats montrent qu'en opposition avec ce qui a été observe sur les phases séparées, les cinétiques de dissolution sont très différentes lorsque les différentes phases sont associées dans l'analogue de chondrite à enstatite : la troilite se dissout bien plus lentement que dans les expériences sur phases séparées alors que l'enstatite se dissout plus vite. La dissolution plus lente de la troilite est attribuée à la présence de monosulfures très solubles dans le matériau de départ. Ces observations pourront être utilisées pour modéliser et interpréter l'évolution d'une chondrite à enstatite à la surface de la Terre et, au delà, de matériaux réduits associant métaux, sulfures et silicates. Les chondrites à enstatite constituent un substrat approprié pour les deux souches bactériennes étudiées qui, en présence de cet assemblage minéral, ont montré de l'activité biologique, en particulier la formation de biofilms, et ont accéléré les vitesses de dissolution

Acid mine drainage (AMD) is a worldwide environmental problem associated with the mining wastes, generated from active and inactive mining sites from mineral processing activities. AMD is defined as the drainage that occurs as a result of oxidation of sulphide minerals/wastes/tailings when exposed to air and water in the presence of chemolithotrophs namely the Acidithiobacillus sp. AMD is characterised by low pH and increased acidity due to elevated heavy metals and sulphate concentration. The acid production potential was carried out for sulphide minerals such as pyrite and chalcopyrite and copper tailings sample in the absence and presence of bacteria namely Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Acidity was generated in all the cases due to the oxidation of the mineral samples. The oxidation was found to occur at a higher rate in the presence of the bacteria compared to the control samples. Bioremediation experiments were conducted on acid mine water collected from the Ingaldahl Mines, Chitradurga, Karnataka, India, using organic and inorganic substrates. In the experiments with rice husk, complete removal of metal ions from the acid mine water was achieved with an attendant increase in the pH of the acid mine water from 2.3 to 5.5. About 21% of sulphate could be removed using Dsm. nigrificans from acid mine water pretreated with rice husk at pH 5.5 and this was further increased to 40% by the supplementation of organic components. The rice husk filtrate was found to serve as a good growth medium for Dsm. nigrificans. About 96 % of Fe, 75 % of Zn, 92 % of Cu and 41 % of sulphate removal was achieved from the acid mine water of pH 2.4 with a concomitant increase in the pH value by two units after interaction with the tree bark. About 56 % and 71 % of sulphate reduction could be achieved at initial pH values of 4.1 and 5.5 respectively of the acid mine water pretreated with E. tereticornis (Sm) bark, after inoculation with Dsm. nigrificans. The complete removal of Fe2+ and Fe3+, 80% of Zn, 83% of Cu and 62% of sulphate could be removed from acid mine water using fly ash as the substrate with an increase in pH of acid mine water from 2.3 to 7. About 68% of sulphate reduction at pH 6.8 could be achieved in acid mine water pretreated with fly ash in the presence of Dsm. nigrificans. With red mud as the substrate, complete removal of all the metal ions namely Fe2+, Fe3+, Zn, and Cu from acid mine water was achieved with a concomitant increase in the pH from 2.3 to 8. The sulphate reduction was increased to about 51% at pH 7.2 when the acid mine water pretreated with red mud was inoculated with Dsm. nigrificans. The adsorption experiments carried out on the acid mine water using either organic or inorganic substrates indicated that the free energy of adsorption was negative for all the chosen metal ions attesting to favorable interaction. The adsorption isotherms of the metal ions for rice husk exhibited Langmuirian behaviour, while those for the other substrates adhered to both Langmuir and Freundlich relationships. The adsorption process was found to be endothermic in nature for rice husk, fly ash and red mud. On the contrary, the adsorption onto tree bark showed exothermic behaviour. The adsorption kinetics of the metal ions onto the various substrates adhered to the first order Lagergren equation. The metal uptake processes by the organic and inorganic substrates chosen for this study involve ionic, chemical and physical forces of adsorption. The different types of functional groups present on the surface of the substrates such as carboxyl, hydroxyl and carbonyl, as revealed by FTIR spectroscopic studies, partake in metal binding. The metal ions will also be adsorbed by complexing with the negatively charged reaction sites on the substrate surfaces. Furthermore, the complex solution chemistry of the metals as a function of pH has also to be taken into consideration. The mechanism of sulphate reduction by Dsm. nigrificans in the presence of organic carbon can be illustrated as: 2CH2O + SO42- + 2H+  2CO2 + 2H2O + H2S M2 + H2S  MS  + 2H+ where, CH2O represents the organic matter and M represents the metal ion.