[pt] Concentrado minerais sulfetados são uma importante fonte de matérias-primas nos processos de extração de metais não-ferrosos. No que diz respeito ao cobre, estes são usualmente processados segundo um fluxograma contemplando as etapas de ustulação, fusão mática, conversão e refino. Todavia, algumas características dos concentrados podem limitar a sua aceitação nas plantas de processamento tais como: baixo teor de cobre assim como a presença de elementos ditos deletérios, como, por exemplo, o flúor e seus efeitos corrosivos sobre materiais refratários após a transformação e ácido fluorídrico; ainda que o material possua um teor do metal de interesse elevado. Dentro desse contexto, o presente trabalho tem por objetivo avaliar o processamento químico de concentrados sulfetados de cobre com essas características a fim de entender o seu comportamento nos processos de ustulação, visando à identificação de condições que minimizem os efeitos danosos do flúor, no caso de concentrados de alto, assim como determinar uma janela operacional que possibilite a obtenção seletiva de CuSO4, no caso de concentrados de baixo teor. Para atender a esses objetivos, foi levado a efeito um estudo teórico incluindo uma breve revisão da literatura e uma apreciação termodinâmica das reações químicas mais relevantes em cada sistema reacional. O estudo experimental foi conduzido através da avaliação do efeito de variáveis específicas para cada sistema reacional. No caso particular de concentrados de alto teor contendo flúor, os experimentos contemplaram a presença, ou não, de água na atmosfera reacional ao passo que nos ensaios envolvendo concentrados de baixo teor de cobre foram levados a efeito variando a temperatura e a composição química da atmosfera reacional a partir da recirculação de parte dos produtos gasosos, como, por exemplo, o SO2. Os materiais envolvidos foram caracterizados por meio de microscopia eletrônica de varredura e difração de raios-x. As previsões teóricas de ambos os sistemas reacionais puderam ser confirmadas na caracterização dos produtos reacionais obtidos após o processamento químico dos concentrados sulfetados de alto e baixo teor de cobre. No que tange o primeiro destes, observou-se que o flúor tende a permanecer estável na forma de fluorita quando na ausência de umidade no sistema reacional. Por outro lado, no que diz respeito ao último destes materiais, verificou-se que o reciclo de parte dos produtos gasosos do processo é responsável por uma melhora de desempenho da reação química de ustulação visando à formação seletiva de sulfato de cobre e óxido de ferro. / [en] Sulfide minerals concentrates are an important source of raw materials for non-ferrous metals extraction processes. For copper, these are usually processed through a flowchart containing the operations of roasting, matte smelting, conversion and refining. However, some concentrates characteristics may limit its acceptance in processing plants such as low copper content and the presence of deleterious elements, such as fluorine and its corrosive effects as result of its transformation into hydrofluoric acid; even if the metal content is this material is high. Within this context, this study aims to evaluate the chemical processing of sulfide concentrates with these characteristics in order to understand their roasting behavior, in order to identify conditions that minimize the fluorine harmful effects for concentrate with high copper content, and determine an operating window that allows the selective obtainment of CuSO4, for low grade concentrates. To meet these objectives, it was carried out a theoretical study including a brief review of the literature and a thermodynamics assessment of the most important chemical reactions in each reaction system. The experimental study was conducted evaluating the effect of specific variables for each reaction system. In the case of concentrates of high grade containing fluorine, the experiments contemplate the presence or absence of water in the reaction atmosphere while the tests involving the concentrate with low copper content were carried out by varying the temperature and the chemical composition of the atmosphere, recirculating part of the gaseous products, like SO2. The materials were characterized by scanning electron microscopy and x-ray diffraction. The theoretical predictions of both reaction systems could be confirmed in the characterization of the reaction products obtained after the chemical processing of sulfide concentrates of high and low copper content. In what touches the former, it was observed that fluorine tends to remain stable as fluorite in the absence of moisture within the reaction system. On the other hand, regarding the latter material, it was found that the part of recycled gaseous products of the process are responsible for a performance improvement of the roasting reaction focused on the selective formation of copper sulfate and iron oxide.

Thesis submitted in fulfilment of the requirements for the degree Master of Technology: Chemical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2011 / Treatment of waste material from mining and mineral processing is gaining increasing importance as a result of the increasing demand for high purity products and environmental concerns. Supported liquid membranes (SLMs) have been proposed as a new technology for the selective removal of metal ions from a solution. This technology can be described as the simultaneous extraction and stripping operation, combined in a continuous single process unit. Theoretically, the rate of mass transfer through SLM systems could be controlled by three resistances, namely: · Resistance through the feed-side · Resistance through the strip-side laminar layers; and · Diffusion through the membrane. It has been reported that transport resistance in the feed-side laminar layer is controlling. (Srisurichan et al, 2005:186). The objective of this research was to extract copper ions in a TSLM system, evaluate the effect of the feed characteristics on the feed-side laminar layer and determine a relationship between the applicable dimensionless numbers, i.e. Sherwood, Schmidt and Reynolds numbers. A Counter-current, double pipe Perspex bench-scale reactor, consisting of a single hydrophobic PVDF tubular membrane mounted vertically within, was used for the test work. The membrane was impregnated with LIX 984N-C and became the support for this organic transport medium. Dilute Copper solution passed through the centre pipe and sulphuric acid, as a strippant, passed through the shell side. In this test work, Copper was successfully transported from the feed-side to the strip-side and through repetitive results; a relationship between dimensionless numbers was achieved.

A dissertation examining technological diversity in Indigenous copper metallurgy of the North American Arctic and Central Subarctic. Variation in technological diversity is assessed cross-culturally, chronologically, and geographically. This is accomplished using diversity statistics to characterize Richness and Evenness of spatiotemporal archaeological assemblages of copper artifacts, performing regression analysis to examine the relationship to the results of a GIS Path Distance analysis that models the cost of acquisition of raw or modified copper, and performing chi-square tests of independence to compare assemblages inter-regionally and temporally. Portable X-Ray Fluorescence was utilized to discriminate geologically pure copper from smelted trade copper and a comprehensive typology of copper artifacts was created using a compiled database of known copper artifacts from across the North American Arctic and central Subarctic. Inter-regional, chronological, and cross-cultural differences in technological diversity were identified and implications for Arctic and Subarctic archaeology and technological innovation are discussed.

M. Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / This work investigates the possible use of chitosan beads and polyaniline grafted chitosan beads (PGCB) for the adsorption of copper ions from copper contaminated water. For this purpose chitosan flakes were converted to chitosan beads. However, a variable from a number of reaction variables (aniline concentration, chitosan concentration, temperature, acid concentration, reaction time and initiator concentration) was varied while others was kept constant, in an attempt to determine the best conditions for grafting of polyaniline onto chitosan beads. Percentage (%) grafting and % efficiency were key parameters used to determine such conditions. The chitosan beads and PGCB were characterized using physical techniques such as Fourier transformed infra red (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The beads were used as an adsorbent for copper ions removal. The effect of pH on the removal rate of copper (II) by PGCB was investigated on by varying the pH values from pH 3 to 8 at an initial concentration of 40 mg/l. The effect of contact time, initial concentration and temperature was also investigated. The Langmuir and Freundlich model were used to describe adsorption isotherms for chitosan beads and PGCB, with correlation coefficient (R2) as the determining factor of best fit model. The thermodynamics of adsorption of copper (II) onto PGCB was described by parameters such as standard Gibb’s free energy change (ΔGo), standard enthalpy change (ΔHo), and standard entropy change (ΔSo) while the pseudo first-order and pseudo second-order kinetic model was used to describe kinetic data for the PGCB, with R2 and chi- square test (  2) as the determinant factor of best fit model. From the desorption studies, the effect of eluants (HCl and HNO3) and contact time on percentage desorption of PGCB loaded copper (II) ion was investigated upon. In determining the reusability of the PGCB loaded copper (II) ion, three cycles of adsorption/desorption studies was carried out. The results obtained from determining the best conditions for grafting polyaniline onto chitosan beads revealed the following grafting conditions; [Aniline] 0.1 g/l, [temperature] 35oC, [chitosan] 0.45 g/l, [HCl] 0.4 g/l, [(NH4)2S2O8] 0.35 g/l, and [time] 1 h. These conditions were applied in the grafting of polyaniline onto chitosan beads. FTIR analysis showed increase intensity in the grafted beads which provided evidence of grafting, XRD measurement showed a decrease in crystallinity in the PGCB as against the partial crystalline nature of chitosan. In SEM analysis, evidence of grafting was revealed by the closed gap between the polysaccharide particles in the PGCB. From the investigation carried out on the effect of pH on the percentage removal of Cu(II) ions by PGCB, the optimal pH value was found to be pH 5 with a percentage removal of 100% and this value was used for all adsorption experiment. Also from the investigation performed on the effect of contact time and initial concentration, it was observed that there was a sharp increase in the amount of Cu(II) ions adsorbed by PGCB up until contact time of 30 min and thereafter, it increases gradually. From the experiment carried out on the effect of temperature on adsorption capacity, there was an increase in adsorption capacity with increase in temperature. Moreover, at temperatures of 25oC, 35 oC and 45oC the Langmuir model gave the best fit for the chitosan beads having R2 values that are equal and greater than 0.942 in contrast to Freundlich having R2 values that is equal and greater than 0.932. The maximum adsorption capacity (Qm) from Langmuir model at these temperatures were 30.3 mg/g, 47.6 mg/g and 52.6 mg/g respectively. Also, the Langmuir model gave the best fit for the PGCB having R2 values that are equal and greater than 0.956 in contrast to Freundlich model with R2 values that is equal and greater than 0.935. The Qm from Langmuir model at these temperatures were 80.3 mg/g, 90.9 mg/g and 100 mg/g respectively. The values of Qm for PGCB appears to be significantly higher when compared to that of chitosan beads and this makes PGCB a better adsorbent than chitosan beads. From the thermodynamic studies carried out on PGCB, the values of ΔGo were negative and this denotes that the adsorption of copper ions onto PGCB is favorable and spontaneous, the positive value of ΔHo shows the adsorption process is endothermic and the positive value of ΔSo illustrate increased randomness at the solid-liquid interface during the adsorption process. Also, from the kinetic studies carried out on the PGCB, the pseudo second-order kinetic model best described the kinetic data having R2 values that are equal and greater than 0.994 in contrast to the pseudo first-order kinetic model with R2 values that is equal and greater than 0.913. The  2 values for the pseudo first-order and pseudo second-order kinetic model were similar; however, there was a large difference for qe between the calculated (qeCal) values of the first-order kinetic model and experimental (qeExp) values. In the case of the pseudo second-order model, the calculated qe values agree very well with the experimental data. Desorption of the metal ions from PGCB was efficient. 0.5 M HCl was successfully used in desorbing the beads loaded with copper ions and a percentage desorption of 97.1% was achieved at contact time of 180 min. PGCB were successfully re-used for adsorption/desorption studies were a Qm of 83.3 mg/g, 83.3 mg/g and 76.9 mg/g was achieved in the first, second and third cycle respectively.

[ES] Esta Tesis Doctoral se centra en la recuperación mediante electrodeposición del Sb presente en un efluente residual proveniente de la metalurgia del cobre. El efluente en el que se basa este estudio se produce en el proceso de regeneración con HCl concentrado de las resinas de intercambio iónico de una de las subetapas del electro-refinado del cobre. Se trata de un electrolito ácido que contiene diversas impurezas, entre las que destacan, Sb y Bi, que son considerados materias primas críticas por la Unión Europea, debido al riesgo de suministro que presentan y a su importancia en la economía. El objetivo de esta Tesis es la recuperación del Sb y la reutilización del HCl. Para alcanzar ambos propósitos se ha estudiado el empleo de la electrodeposición como operación de separación para el tratamiento del efluente. Este proceso se ha investigado mediante técnicas electroquímicas, en particular, voltametría cíclica y de barrido lineal. En primer lugar, se ha realizado el estudio con disoluciones sintéticas que emulan el efluente generado en las metalurgias chilenas. La caracterización electroquímica de la disolución de Sb en medio HCl ha evidenciado que la reducción del Sb(III) a Sb metálico está limitada por la transferencia de materia y que una concentración elevada de HCl favorece la recuperación del Sb. Los ensayos de electrodeposición han destacado la relevancia de las reacciones secundarias, la reacción de evolución del hidrógeno (HER) y la generación de cloro, y su influencia negativa sobre la deposición de Sb. La HER tiene lugar en el cátodo y conlleva la generación de burbujas de hidrógeno a elevadas densidades de corriente, que reducen la superficie útil del electrodo de trabajo e incluso causan el desprendimiento del depósito de Sb. Por su parte, la generación de cloro gas en el ánodo provoca la redisolución de los depósitos de Sb desprendidos a causa de la HER. Tras la realización de estos ensayos se ha concluido que se puede aumentar la tasa de recuperación de Sb si se tienen mayores concentraciones del elemento en la disolución o si se mejoran las condiciones hidrodinámicas. Se ha analizado también cómo influye la presencia de Bi en la disolución sintética durante la electrodeposición del Sb. El potencial de reducción de ambos elementos es similar, lo que implica que la recuperación individual de Sb sea compleja. No obstante, si se trabaja bajo condiciones en las que no se supere la densidad de corriente límite del sistema, se logra una elevada selectividad hacia el Sb. Si la concentración de Bi en la disolución es superior a la de Sb, se electrodepositan ambos elementos, pero se logra un elevado valor de eficiencia de corriente debido a que la influencia de la HER sobre el Bi no es tan fuerte. A continuación, se ha estudiado la aplicación de las técnicas previamente analizadas con un efluente real, facilitado por una empresa española. Se ha verificado que las conclusiones obtenidas con las disoluciones sintéticas son aplicables al efluente real. En particular, se ha confirmado que, al aumentar la densidad de corriente aplicada, la deposición de Sb se ve mermada debido a la relevancia del resto de reacciones: la reducción de los demás elementos y la evolución del medio. Los depósitos obtenidos contienen algunos de los elementos presentes en el efluente real: Sb, Bi, As y Cu, siendo mayoritario el primero. Como resultado, se ha concluido que es posible purificar el HCl mediante la electrodeposición de los elementos contenidos en el electrolito. Finalmente, se ha planteado la posibilidad de sustituir el HCl empleado como regenerante por un disolvente eutéctico profundo, debido a la alta solubilidad de metales y su procedencia de fuentes renovables. En particular, la investigación se ha llevado a cabo con la oxalina, la cual presenta una elevada capacidad de disolución para el Sb y una amplia ventana de potencial que beneficiaría la aplicación de la técnica de electrodeposición para la recuperación del Sb. / [CA] Esta Tesi Doctoral se centra en la recuperació mitjançant electrodeposició del Sb present en un efluent residual provinent de la metal·lúrgia del coure. L'efluent en què es basa este estudi es produïx en el procés de regeneració amb HCl concentrat de les resines d'intercanvi iònic d'una de les subetapes de l'electro-refinat del coure. Es tracta d'un electròlit àcid que conté diverses impureses, entre les quals destaquen, Sb i Bi, que són considerats matèries primeres crítiques per la Unió Europea, a causa del risc de subministrament que presenten i a la seua importància en l'economia. L'objectiu d'esta Tesi és la recuperació del Sb i la reutilització de l'HCl. Per assolir aquests dos propòsits s'ha estudiat l'ús de l'electrodeposició com a operació de separació per al tractament de l'efluent. Este procés s'ha investigat mitjançant tècniques electroquímiques, en particular, voltametria cíclica i de rastreig lineal. En primer lloc, s'ha realitzat l'estudi amb dissolucions sintètiques que emulen l'efluent generat a les metal·lúrgies xilenes. La caracterització electroquímica de la dissolució de Sb en medi HCl ha evidenciat que la reducció del Sb(III) a Sb metàl·lic està limitada per la transferència de matèria i que una concentració elevada de HCl afavorix la recuperació del Sb. Els assajos d'electrodeposició han destacat la rellevància de les reaccions secundàries, la reacció d'evolució de l'hidrogen (HER) i la generació de clor, i la seua influència negativa sobre la deposició de Sb. La HER té lloc al càtode i comporta la generació de bambolles d'hidrogen a elevades densitats de corrent, la qual cosa reduïx la superfície útil de l'elèctrode de treball i fins i tot causa el despreniment del depòsit de Sb. Per la seua banda, la generació de clor gas a l'ànode provoca la redissolució dels depòsits de Sb despresos a causa de la HER. Després de la realització d'estos assajos s'ha conclòs que es pot augmentar la taxa de recuperació de Sb si es tenen majors concentracions de l'element en la dissolució o si es milloren les condicions hidrodinàmiques. S'ha analitzat també com influïx la presència de Bi en la dissolució sintètica durant l'electrodeposició del Sb. El potencial de reducció dels dos elements és similar, la qual cosa implica que la recuperació individual de Sb siga complexa. No obstant això, si es treballa sota condicions en què no se supere la densitat de corrent límit del sistema, s'aconseguix una elevada selectivitat cap al Sb. Si la concentració de Bi en la dissolució és superior a la de Sb, s'electrodepositen ambdós elements, però s'aconseguix un elevat valor d'eficiència de corrent pel fet que la influència de la HER sobre el Bi no és tan forta. A continuació, s'ha estudiat l'aplicació de les tècniques prèviament analitzades amb un efluent real, facilitat per una empresa espanyola. S'ha verificat que les conclusions obtingudes amb les dissolucions sintètiques són aplicables al efluent real. En particular, s'ha confirmat que, en augmentar la densitat de corrent aplicada, la deposició de Sb es veu minvada a causa de la rellevància de la resta de reaccions: la reducció dels altres elements i l'evolució del medi. Els depòsits obtinguts contenen alguns dels elements presents en el efluent real: Sb, Bi, As i Cu, sent majoritari el primer. Com a resultat, s'ha conclòs que és possible purificar l'HCl mitjançant l'electrodeposició dels elements continguts en l'electròlit. Finalment, s'ha plantejat la possibilitat de substituir l'HCl emprat com regenerant per un dissolvent eutèctic profund, a causa de l'alta solubilitat de metalls i la seua procedència de fonts renovables. En particular, la investigació s'ha dut a terme amb l'oxalina, la qual presenta una elevada capacitat de dissolució per al Sb i una àmplia finestra de potencial que beneficiaria l'aplicació de la tècnica d'electrodeposició per a la recuperació del Sb captat durant el procés de regeneració de les resines. / [EN] This Doctoral Thesis focuses on the recovery by electrodeposition of Sb present in an effluent from the copper metallurgy. The effluent on which this study is based is generated during the regeneration with concentrated hydrochloric acid of the ion exchange resins used in one of the sub-stages of copper electro-refining. It is an acid electrolyte containing several impurities, among them, Sb and Bi, which are considered critical raw materials by the European Union due to their supply risk and economic relevance. The aim of this Thesis is the recovery of Sb and reuse of HCl. To achieve both objectives, electrodeposition has been studied as a separation operation for the treatment of the effluent. This operation has been investigated through electrochemical techniques, primarily, cyclic and linear sweep voltammetry. First, the study has been conducted with synthetic solutions emulating the effluent generated in the Chilean metallurgy industries. The electrochemical characterization of the Sb solution in the HCl medium has shown that, mass-transfer limits the reduction of Sb(III) to metallic Sb and a high HCl concentration favors the recovery of Sb. From the electrodeposition tests the relevance and negative influence on Sb deposition of the secondary reactions, the hydrogen evolution reaction (HER) and the chlorine generation, has been proven. The HER occurs at the cathode and involves the generation of hydrogen bubbles at high current densities, which decrease the effective surface area of the working electrode and even cause the detachment of the Sb deposits. The chlorine generation at the anode leads to the redissolution of the Sb deposits detached by the HER. After conducting these experiments, it has been concluded that it is possible to increase the Sb recovery rate, if higher concentrations of this element are present in the solution or the hydrodynamic conditions of the electrodeposition process are improved. The influence of the presence of Bi in the synthetic solution on the Sb electrodeposition has also been investigated. The reduction potential of both elements is similar, implying that the individual recovery of Sb by electrodeposition is challenging. However, if the operating conditions do not imply exceeding the limiting current density of the system, a high electrodeposition selectivity towards Sb is achieved. If the concentration of Bi in the solution is higher than that of Sb, the simultaneous electrodeposition of both elements takes place, but, on the contrary, a high value of current efficiency is obtained because the influence of the HER on Bi reduction is not as significant as that on Sb deposition. The application of the previously analyzed techniques has been studied with a real effluent, that was provided by a Spanish company. It has been proven that the conclusions obtained with the synthetic solutions can be applied to a real effluent. It has been confirmed that, as the applied current density increases, the Sb deposition worsens due to the relevance of the other reactions that take place during the process: the reduction of the other elements and the evolution of the medium. The deposits obtained contain some elements present in the real effluent: Sb, Bi, As and Cu, the most significant being the first. From this study, it has been concluded that purifying the HCl by removing the elements contained in the electrolyte via electrodeposition is possible. Finally, the possibility of replacing the HCl used as a regenerant with a deep eutectic solvent has been considered based on their properties, among which are a high solubility of metals and their synthesis from renewable sources. In particular, the research has been carried out with oxaline, which presents a high dissolution capacity for Sb and a wide potential window that would benefit the application of the electrodeposition technique to recover Sb captured during the resins regeneration process. / Me gustaría agradecer la financiación a la Agencia Estatal de Investigación (AEI/10.13039/501100011033) (España) bajo el proyecto PCI2019-103535, gracias al cual he podido desarrollar la presente Tesis Doctoral, y a FEDER Una manera de hacer Europa / Hernández Pérez, L. (2024). Estudio electroquímico para la recuperación de antimonio de efluentes del electro-refinado de cobre por electrodeposición [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203892