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The main aim of this work was to test the ability of an amino acid (i.e. glycine) to leach cobalt from Li ion batteries (LiBs). The process parameters namely temperature, pulp density and concentration of glycine were optimized for maximizing the leaching efficiency of cobalt from the cathodic material. Response surface methodology (RSM) was applied for determining the experimental conditions instead of using the traditional one factor at a time (OFAT) approach in order to ascertain the interaction effects between the different factors. Thus, the optimal leaching value based on RSM and maximum cobalt leaching potential from LiBs was obtained. The optimum values for the parameters were as follows; temperature = 74 °C, pulp density = 19.9 g/L and glycine concentration = 0.936 M. Under this optimum condition, the cobalt leaching efficiency was 61.8%, while a maximum leaching of 89.7% was achieved at the following conditions: temperature = 100 °C, pulp density = 13.8 g/L and glycine concentration = 1.24 M. Oxalic acid was used for recovering cobalt from the leaching solution by varying the pH and molar ratio of oxalic acid and cobalt ions. Cobalt recovery efficiencies were 88.0% at pH 7.0 and at oxalic acid to cobalt ion molar ratio of 2.5:1.0.

Rohstoffe sind seit alters her eine wesentliche Voraussetzung für die Entwicklung von Gesellschaft und Industrie. Dabei spielen sowohl mineralische und metallische Massenroh-stoffe eine entscheidende Rolle als auch jene Rohstoffe, die in nur vergleichsweise geringen Mengen eingesetzt werden und gerade für die heutige und zukünftige Produktion von Hoch-technologieprodukten von besonderer Relevanz sind. Die Verfügbarkeit dieser wirtschafts-strategischen Rohstoffe ist jedoch begrenzt, weshalb viele von ihnen auf der Liste der kritischen Rohstoffe 2017 der Europäischen Kommission geführt werden. Zu ihnen zählen u.a. auch Indium und Gallium. Selbst bei einem flächendeckenden und effizienten Recycling ist der steigende Rohstoffbedarf aus Abfällen nicht zu decken, weshalb auch in Zukunft auf die Primärrohstoffproduktion nicht verzichtet werden kann. Zahlreiche wirtschaftsstrategische Rohstoffe bilden jedoch keine eigenständigen Erzminerale aus, sondern liegen als Begleitelemente in anderen Wertträgern vor oder sie treten nicht in ausreichend hoher Konzentration auf, um eine darauf abgestimmte Erzgewinnung aufzubauen. Vielmehr steht die Gewinnung der Hauptmetallträger im Fokus. Im Verbund damit ist dann die Gewinnung der beibrechenden wirtschaftsstrategischen Metalle zu gestalten. Die vorliegende Arbeit hat sich zum Ziel gesetzt, ein Aufbereitungsverfahren zu entwickeln, welches für zwei Gallium- bzw. Indium-haltige sulfidische Blei-Zink-Erze aus Lautenthal im Harz (Querschlag 500 West und Querschlag 700 West) alle Prozessschritte, von der Zerkleinerung bis hin zur ionenselektiven Trennung mittels Ionenaustauschern, umfasst und dabei neben der Gewinnung der Hauptmetalle die beibrechenden Metalle in den Fokus nimmt. Der erste Schritt des Verfahrens basiert auf dem seit Jahrzenten bewährten Prozess der Flotation, so dass sowohl der Bleiglanz als auch die Zinkblende jeweils in ein Konzentrat überführt werden. Die beiden Sondermetalle Gallium und Indium reichern sich gemäß den Erwartungen im Zinkblendeflotat an. In diesem ersten Schritt konnten für das Erz aus Querschlag 500 West rund 88 % des Bleis, 96 % des Zinks und 94 % des Galliums in das Flotationskonzentrat überführt werden. Für jenes aus Querschlag 700 West wurden Aus-bringen von 92 % Blei und 96 % Zink erzielt sowie 95 % des Indiums und 75 % des Galliums in die Konzentrate überführt. Anschließend wurde für eine verbesserte hydrometallurgische Verarbeitung eine thermische Behandlung der Zinkkonzentrate vor einer schwefelsauren Laugung eingesetzt, so dass für 500 West 97 % des Zinks und 85 % des Galliums in Lösung gebracht wurden (700 West: 96 % Zn, 91 % Ga, 94 % In). Für die ionenselektive Trennung haben sich zwei Ionenaustauscher als geeignet herausgestellt, welche unterschiedliche Ergebnisse generierten. In einen Fall wurde eine gute Selektivität bei gleichzeitig geringerem Ausbringen erzielt, während im anderen Fall hohe Ausbringen, verbunden mit einer etwas geringeren Selektivität nachgewiesen werden konnten. Für beide Fälle wäre eine praktische Umsetzung möglich, so dass keine der beiden Varianten bevorzugt zu behandeln ist. Bei kontinuierlicher Beschickung der Ionenaustauscher können nach vollständiger Beladung und Regenerierung des Harzes theoretischen Berechnungen zufolge die Mindestanforderungen der potentiellen Abnehmer für eine Weiterverarbeitung der Indium- und Galliumhaltigen Lösungen erfüllt werden., Raw materials have always been an essential prerequisite for the development of society and industry. Both, mineral and metallic raw materials play a decisive role, as well as raw materials that are used in only comparatively small quantities. The latter are particularly relevant for the present and future production of highly technological products. However, the availability of these strategic raw materials is limited. For that reason, many of these critical raw materials have been recorded on the so-called “2017 list of critical raw materials for the European Union”, including indium and gallium. Even with widespread and efficient recycling, the increasing demand for these critical raw materials cannot be covered from the recycling of waste material containing such materials. Therefore, it will not be possible to do cover the needs without mining and processing primary raw materials in the future. However, numerous strategic raw materials usually do not form their own minerals, but are present as accompanying elements in other valuable minerals or they do not occur in a sufficiently high concentration in order to build up a coordinated processing. In these cases, the focus is mostly on recovering the main metal component of such an ore and not the related elements present in low concentrations. Consequently, a fully new approach for the extraction of strategic metals has to be devised. The aim of the present work is to develop a processing method that covers all process steps from comminution to ion-selective separation by ion exchangers to focus on the extraction of the main metals as well as the strategic metals. This work particularly focusses on two gallium- or indium-containing sulfidic lead-zinc ores from Lautenthal in the Harz Mountains (crosscut 500 west and crosscut 700 west). The first step of the new process is flotation, which has been tried and tested for decades, in order to enrich both galena and sphalerite in separate concentrates. As can be expected, the metals gallium and indium accumulate in the sphalerite concentrate. In this first step, around 88 % of lead, 96 % of zinc and 94 % of gallium can be transferred to the flotation concentrate. For the ore from crosscut 700 west, recoveries of 92 % for lead, 96 % for zinc, 95 % for indium and 75 % for gallium have been achieved and were thus transferred to the concentrates. Subsequently, for an improved hydrometallurgical processing, a thermal treatment of the zinc concentrates was used before leaching with diluted sulfuric acid. For the sample 500 west, 97 % of zinc and 85 % of gallium present in the ore were brought into solution (700 west: 96 % Zn, 91 % Ga, 94 % In). It has been established that two ion exchangers, which generated different results, are suitable for the ion-selective separation. In one case, good selectivity was achieved with a lower recovery at the same time, while in the other case high recoveries combined with a lower selectivity could be demonstrated. A practical implementation can be envisaged for both cases, therefore neither of the two process routes is to be treated preferentially. Theoretical calculations show that with continuous feeding of the ion exchanger and after the complete loading and regeneration, the minimum requirements of the potential customers for further processing of the indium and gallium containing solutions can be met.

We present the preparation and characterization of pure lead monoxide obtained through recycling of the lead paste recovered from exhausted lead acid batteries. The recycling is based on a hydrometallurgical procedure reported in a STC Patent, that includes simple chemical operations (desulphurisation, leaching, precipitation, filtration) and a final thermal conversion. Materials obtained by treatment at 600 °C consist predominantly of β-PbO. The electrochemical behaviour of Positive Active Mass (PAM) prepared from different materials (or mixtures) is then investigated and compared. An optimized oxide material, obtained by prolonged (8 h) thermal treatment at 600 °C, consists of pure β-PbO and appears suitable for preparation of battery elements, alone or in mixture with a small fraction (10%–30%) of traditional industrial leady oxide. The resulting battery performances are similar to those obtained from pure leady oxide. In comparison with traditional recycling processes, the proposed method guarantees lower energy consumption, limited environmental impact and reduced operating risk for industry workers.

The main objective of this manuscript is the description of a mobile demonstration plant designed and built for the recovery of metals from waste of electrical and electronic equipment and other waste such as spent batteries and exhausted industrial catalysts. The plant was designed within the European FP7 framework HydroWEEE-demo (2012–2016) and can offer an effective proposal to addressing the problem of the electronic waste, reducing the environmental impact of their not correct disposal, recovering critical materials as rare earths and precious elements, and giving economic benefits, moreover by it, it is possible to overcome the problem of moving hazardous wastes from one country to another one. Details about the process to recover rare earths from fluorescent materials are presented. Two alternative treatments are showed with and without recirculation of the residual solutions. Economic analysis shows that with the actual product price (14 €/kg) only the process, in which solution recirculation is present, provides a return on the investment. Positive gain is possible if the plant works at its highest capacity and if the price growths up to 20 €/kg the gain increases about 20% of operating costs (process with recirculation, 2 batch/day). In the process without recirculation of the solution, to obtain the same ratio between gain and operating cost it is necessary that the price increases up to 26 €/kg. About other e-wastes, economic analysis has shown that the highest gain is provided from the PCB treatment.

Waste electrical and electronic equipment (WEEE) contains economically significant levels of precious, critical metals and rare earth elements, apart from base metals and other toxic compounds. Recycling and recovery of critical elements from WEEEs using a cost-effective technology are now one of the top priorities in metallurgy due to the rapid depletion of their natural resources. More than 150 publications on WEEE management, leaching and recovery of metals from WEEE were reviewed in this work, with special emphasize on the recent research (2015–2018). This paper summarizes the recent progress regarding various hydrometallurgical processes for the leaching of critical elements from WEEEs. Various methodologies and techniques for critical elements selective recovery (using ionic liquids, solvent extraction, electrowinning, adsorption, and precipitation) from the WEEEs leachates are discussed. Future prospects regarding the use of WEEEs as secondary resources for critical raw materials and its techno-economical and commercial beneficiaries are discussed.

Printed circuit boards (PCBs), a typical end-of-life electronic waste, were collected from an E-waste recycling company located in the Netherlands. Cu and precious metal concentration analyses of the powdered PCBs confirm that the PCBs are multimetallic in nature, rich, but contain high concentrations of Cu, Au, Ag, Pd, and Pt. Ferric sulfate concentration (100 mM), agitation speed (300 rpm), temperature (20 °C), and solid-to-liquid ratio (10 g·L−1) were found to be the optimum conditions for the maximum leaching of Cu from PCBs. The ferric sulfate leachates were further examined for selective recovery of Cu as copper sulfides. The important process variables of sulfide precipitation, such as lixiviant concentration and sulfide dosage were investigated and optimized 100 ppm of ferric sulfate and (copper:sulfide) 1:3 molar ratio, respectively. Over 95% of the dissolved Cu (from the multimetallic leachates) was selectively precipitated as copper sulfide under optimum conditions. The characterization of the copper sulfide precipitates by SEM-EDS analyses showed that the precipitates mainly consist of Cu and S. PCBs can thus be seen as a potential secondary resource for copper.

Purpose: the metals and industrial minerals contained in the tailings produced by mining and quarrying activities, are cause of environmental damage. The objective of this experimental work is the application of innovative technologies for the treatment and exploitation of mining tailings in Romania, in order to recover materials high grade raw to be placed on the market, reducing the volume of the wastes. Further objective, is to optimize some parameters relating to the dissolution of gold and the subsequent recovery from purified solutions, determining beforehand the technical feasibility of the scheme of process developed on a laboratory scale. Methods: the study is focused on hydrometallurgical process for the recovery of gold. The innovative treatment chosen is the thiosulphate process that, compared to conventional cyanide, has several advantages, first of all the most eco-friendly and non- toxic to humans. The conventional process shows operating limits in the case of auriferous minerals refractory materials, such as Romanian wastes object of the study. Another fundamental characteristic of the ammoniacal thiosulphate solutions, is the best selectivity towards gold, not attacking the majority of the gangue mineral constituents. Results: the dissolution rates of gold reached a final value of 70% Au - working at room temperature - with recoveries of the global process of about 65%, in line with the conventional process. Main conclusions: these results are very encouraging, considering that this is an innovative process, applied to a low content gold ore. The optimization of parameters and operating conditions, and the industrial treatment, continuous and scale greater would certainly permit to reach the best results in terms of process yields and energetic and reagents consumption.

The metals and industrial minerals contained in the tailings produced by mining and quarrying activities, are cause of environmental damage. The objective of this experimental work is the application of innovative technologies for the treatment and exploitation of mining tailings in Romania, in order to recover materials high grade raw to be placed on the market, reducing the volume of the wastes. Further objective, is to optimize some parameters relating to the dissolution of gold and the subsequent recovery from purified solutions, determining beforehand the technical feasibility of the scheme of process developed on a laboratory scale. The study is focused on hydrometallurgical process for the recovery of gold. The innovative treatment chosen is the thiosulphate process that, compared to conventional cyanide, has several advantages, first of all the most eco-friendly and non- toxic to humans. The results achieved so far are very encouraging and would certainly permit to improve the process yields, energetic and reagents consumption.

The metals and industrial minerals contained in the tailings of mining and quarrying activities, can degrade natural environments as well as human health. The objective of this experimental work is the application of innovative and sustainable technologies for the treatment and exploitation of mining tailings from Romania. Within this approach, the recovery of high grade raw materials to be placed on the market is achieved and reduction of these wastes volume are achieved. The current study is focused on hydrometallurgical process for the recovery of gold. The innovative treatment chosen is the thiosulphate process that, compared with the conventional cyanide, has several advantages (e.g., it is more ecologically friendly and is not toxic to humans). The conventional cyanidation process shows operating limits in the case of auriferous refractory minerals, such as Romanian wastes, the object of the study. An important characteristic of thiosulphate leaching process it has the best selectivity towards gold, it does not attack the majority of the gangue mineral constituents. Gold extraction of 75% was obtained under ambient conditions of temperature. Moreover, the overall process achieved about 65&ndash, 67% Au recovery, this being in line with the conventional cyanidation process. As these results are obtained by application of the thiosulfate process on a low gold content ore, they may be considered encouraging. The optimization of process parameters and operating conditions, should permit the best results in terms of process yields to be achieved.

This article presents a copper leaching process from chalcopyrite concentrates using a low-pressure reactor. The experiments were carried out in a 30 L batch reactor at an oxygen pressure of 1 kg/cm2 and solid concentration of 100 g/L. The temperature, particle size and initial acid concentration were varied based on a Taguchi L9 experimental design. The initial and final samples of the study were characterized by chemical analysis, X-ray diffraction and particle size distribution. The mass balance showed that 98% of copper was extracted from the chalcopyrite concentrate in 3 h under the following experimental conditions: 130 g/L of initial sulfuric acid concentration, temperature of 100 &deg, C, oxygen pressure of 1 kg/cm2, solid concentration of 100 g/L and particle size of &minus, 105 + 75 &mu, m. The ANOVA demonstrated that temperature had the greatest influence on copper extraction. The activation energy was 61.93 kJ/mol. The best fit to a linear correlation was the chemical reaction equation that controls the kinetics for the leaching copper from chalcopyrite. The images obtained by SEM showed evidence of shrinking in the core model with the formation of a porous elemental sulfur product layer.

Выполняются исследования комплексной переработки медно-цинковых промпродуктов обогащения сульфидных полиметаллических руд с применением энергоэффективных гидрометаллургических технологий, позволяющих повысить степень извлечения ценных компонентов в товарную продукцию и уровень экологизации производства. Performed studies of complex processing of copper-zinc beneficiation middlings of sulphide polymetallic ores with energy-efficient hydrometallurgical technologies to increase the recovery of valuable components into commercial products and the level of cleaner production.

En esta investigación se determinó la velocidad de corrosión (Vcorr) de hierro ASTM A36, en soluciones de cianuro de sodio en concentraciones de 0,62 g/L; 0,80 g/L y de tiourea 0.96 g/L; 1.24 g/L. Adicionalmente se evaluó el efecto de este deterioro en los costos asociados a procesos de lixiviación aurífera. La velocidad de corrosión se determinó en mm/año mediante curvas de polarización. Se realizó un análisis de costos utilizando indicadores sintéticos. Los resultados muestran que la velocidad de corrosión del metal es ligeramente mayor en la solución de tiourea 1,24 g/L (3,03 mm/año) con el siguiente comportamiento: corrosión de hierro ASTM A36 en Tiourea 1,24g/L > Tiourea 0,96 g/L > Cianuro 0,80 g/L ≈ Cianuro 0,62 g/L. Se pudo estimar que los costos por corrosión en los procesos de lixiviación aurífera se encuentran entre el 4,78 y 5,20% del capital para cianuro y tiourea respectivamente., The objective of this research was to determine corrosion rate (Vcorr) iron ASTM A36, in solutions of sodiumx cyanide and thiourea. Further evaluate the effect of this electrochemical phenomenon in costs associated with gold leaching processes. The corrosion rate was determined in mm / year by polarization curves. Costs were determined by a cost analysis using synthetic indicators. The corrosion rate of iron ASTM A36 in sodium cyanide solutions in concentrations of 0.62 g / L; 0.80 g / L and thiourea solutions 0.96 g / L; 1.24 g / L was evaluated. The results show that the corrosion rate of the metal is slightly higher in the solution of thiourea 1.24 g / L (3.03 mm / year) with the following behavior: Thiourea 1.24g / L> Thiourea 0.96 g / L> Cyanide 0.80 g / L ≈ Cyanide 0.62 g / L. It was estimated that corrosion costs in gold leaching processes are between 4.78 and 5.20% of the capital for cyanide and thiourea respectively.

In 2010 indium was identified by the European Commission as a critical raw material for its economic importance and the supply risk. This metal represents a component of many electronic equipment and therefore its request is high; this fact favors indium recycling. The present study has been carried within the European project FP7 308549 HydroWEEE Demo. It deals with the recovery process of indium from end-of-life liquid crystal displays (LCDs). We carried out a hydrometallurgical process that included a stage of LCD washing followed by metal leaching in a sulfuric acid solution using a cross-current design. The final step of the treatment consisted of zinc cementation that allowed to obtain the transfer in the solid phase of indium present in the leach liquor. The whole process reached an indium recovery efficiency > 90%, and thanks to the cross-current leaching a lower amount of acid was used compared to conventional leaching.

On a resource management level, batteries could be considered as an ore of secondary raw materials, because of their high content in useful metals, such as zinc and manganese; moreover, disposal of spent batteries constituted a serious environmental problem in terms of heavy metals content, when these devices are disposed off in inadequate way. Main processes applying for treatment of the batteries are the pyrometallurgical processes, that involve high energetic consumption and pollution problems, and hydrometallurgical processes, chipper and at low energetic cost. The experimental activity of the present work involve the utilisation of technology well know in the framework of the mineral processing and the metal dissolution by hydrometallurgical processes for Mn-Zn recovery from wastes, constituted by spent alkaline batteries. The results have demonstrated the technical feasibility of the application of the mentioned technologies; in fact, high recovery of manganese and zinc dissolved in solution were achieved (over 90%).

This paper represents a preliminary step to determine the possibility for valorisation of residue organic substances, coming from agro-industrial activities, in a hydrometallurgical circuit. The idea started to develop a production process for manganiferous products of industrial interest, such as MnO2, by using an innovative chemical leaching, at low environmental impact. The experimental activity was conducted at laboratory scale, utilising manganiferous ores. Sulphuric acid was used as leaching agent, while sugar was added as carbohydrate, to simulate the presence of molasses from agro-industrial activities. The main goal of the experimental activity was the electrolytic manganese dioxide recovery, at high degree of purity, from leaching solutions containing Mn, by electrowinning process, also considering the effect of the presence of impurities, such as organic substances and iron. Electrowinning lab-scale operations were conducted to determine the process parameters and to evaluate the quality of the deposit. The purity of the MnO2 residues was determined by diffractometric analysis (RXD). The results show that, also in presence of iron and sugar in leaching solution, it is possible to achieve high MnO2 recovery after electrowinning process (95%). The energetic consumption increases from about 1 kWh/kg (pure solution containing only Mn) to about 2 kWh/kg, in the case of contemporaneous presence of Mn, Fe3+ and sugar in solution. The further work consists in the scale up of the process in continue system, utilising molasses from agro-industrial activities to perform the leaching tests.

Results of studies carried out by different institutes of National Research Council (CNR) in the field of waste treatment, recovery and disposal are shown in this paper. The above institutes are included in the CNR Departments of Earth and Environment, Energy and Transports and Molecular Design. The research activities are related to waste incineration, production of a solid recovered fuel (SRF) by means of an innovative process, monitoring of gas produced by landfill sites, recovery of metallurgical waste and of metals from electronic and exhaust batteries, and recovery of wastes produced by the gold industry.

In this work, hydrometallurgical processes have been applied starting from spent alkaline batteries. Main aim of the research was to develop a preliminary experimental work to recover selectively MnO2 and Zn from leaching solution containing Mn and Zn, both at concentration of 10 g dm-3, by electrolysis, with the scope to apply electrochemical technologies for Zn and Mn recovery from exhaust batteries. The results have demonstrated the technical feasibility of the application of the mentioned technologies; in fact, high recoveries of manganese and zinc dissolved in solution were achieved (97 % MnO2 and 98.50 % Zn).

Extraction of Vanadium and Nickel from waste material was investigated using alkaline and acidic leaching systems. Spent catalyst coming from manufacture of sulfuric acid (3.5% V and 0.63% Ni) and boiler ash (25% V and 13% Ni) can be used as a secondary source of metals. Statistical design of experiments and analysis of variance (ANOVA) were performed in order to determine the main effects and interactions of the investigated factors, which were temperature of roasting and leaching; concentration of the leaching reagent (H2SO4/NaOH); pulp concentration and process time. ANOVA shows that roasting step is the main factor with positive effect on the recovery of metals, whereas pulp concentration shows a negative effect probable due to the inefficient mixing.

A leaching process of gold-bearing refractory and complex ores has been studied by using chlorine dissolved in brine solutions comparing these results with a standard cyanidation process. Chlorine is locally generated with the same brine solution by electrolysis that also produces the sodium hydroxide needs for the proposed process for the neutralisation phase of the barren solutions. These precipitation reactions restore the presence of NaCl that may be recycled in the process after a suitable pre-treatment. Some simulation and experimental results are present to highlight limits and advantages of the proposed process. A comparison with conventional cyanidation has been also reported.

n 1999, global copper production is based on a 80 % in low-grade ores , the metal content is below 2 %. This has focused research efforts - to develop alternative ways to cough pyrometallurgical processes such as hydrometallurgical extraction processes . Since the advent of the first commercial extractants in markets 30 years ago (LIX 63 ), research was directed towards the study of properties such as selectivity , kinetics and solubility at different pH values ​​. Copper, due to its electronic configuration and their different oxidation states , complexes in which the ligands have to have specific selectivity and stability in the organic phase. In the experimental part of this work , complexes of Cu ( I) and Cu ( II ) with anionic and neutral chelating ligands according to their electrochemical properties were studied. En 1999, la producción mundial de cobre se basa en un 80% en minerales pobres, cuyo contenido de metal está por debajo del 2%. Esto ha orientado los esfuerzos de -investigación hacia el desarrollo de vias alternativas a tos procesos pirometalúrgicos, como son los procesos de extracción hidrometalürgicos. Desde la aparición de los primeros extractantes comerciales en los mercados hace 30 años (LIX 63), la investigación se orientó hacia el estudio de propiedades tales como selectividad, cinética y solubilidad a diferentes valores de pH. El cobre, debido a su configuración electrónica y a sus diferentes estados de oxidación, forma complejos en los cuales los ligandos deben tener una selectividad específica y estabilidad en la fase orgánica. En la parte experimental de este trabajo, se estudian complejos del Cu(I) y Cu(II) con ligandos quelantes aniónicos y neutros, de acuerdo a sus características electroquímicas.

En 1999, la producción mundial de cobre se basa en un 80% en minerales pobres, cuyo contenido de metal está por debajo del 2%. Esto ha orientado los esfuerzos de -investigación hacia el desarrollo de vias alternativas a tos procesos pirometalúrgicos, como son los procesos de extracción hidrometalürgicos. Desde la aparición de los primeros extractantes comerciales en los mercados hace 30 años (LIX 63), la investigación se orientó hacia el estudio de propiedades tales como selectividad, cinética y solubilidad a diferentes valores de pH. El cobre, debido a su configuración electrónica y a sus diferentes estados de oxidación, forma complejos en los cuales los ligandos deben tener una selectividad específica y estabilidad en la fase orgánica. En la parte experimental de este trabajo, se estudian complejos del Cu(I) y Cu(II) con ligandos quelantes aniónicos y neutros, de acuerdo a sus características electroquímicas., n 1999, global copper production is based on a 80 % in low-grade ores , the metal content is below 2 %. This has focused research efforts - to develop alternative ways to cough pyrometallurgical processes such as hydrometallurgical extraction processes . Since the advent of the first commercial extractants in markets 30 years ago (LIX 63 ), research was directed towards the study of properties such as selectivity , kinetics and solubility at different pH values ​​. Copper, due to its electronic configuration and their different oxidation states , complexes in which the ligands have to have specific selectivity and stability in the organic phase. In the experimental part of this work , complexes of Cu ( I) and Cu ( II ) with anionic and neutral chelating ligands according to their electrochemical properties were studied.

The aim of this investigation was to compare the influence of the main process variables of cyanidation and thioureation on gold recovery. The investigation was carried out on a finely disseminated gold-bearing ore (5 g/t Au). The main parameters utilised in the leaching tests have been: oxidizing agent (O2, Fe3+), leaching agent (NaCN, CS(NH2)2), pH, temperature, pulp density and leaching time. The optimisation of the parameters permitted to obtain about 85% Au recovery in both the processes.