Exotic type deposits include several species of minerals, such as atacamite, chrysocolla, copper pitch, and copper wad. Among these, copper pitch and copper wad have considerable concentrations of manganese. However, their non-crystalline and amorphous structure makes it challenging to recover the elements of interest (like Cu or Mn) by conventional hydrometallurgical methods. For this reason, black copper ores are generally not incorporated into the extraction circuits or left unprocessed, whether in stock, leach pads, or waste. Therefore, to dilute MnO2, the use of reducing agents is essential. In the present research, agitated leaching was performed to dissolve Mn of black copper in an acidic medium, comparing the use of ferrous ions and tailings as reducing agents. Two samples of black copper were studied, of high and low grade of Mn, respectively, the latter with a high content of clays. The effect on the reducing agent/black copper ratio and the concentration of sulfuric acid in the system were evaluated. Better results in removing Mn were achieved using the highest-grade black copper sample when working with ferrous ions at a ratio of Fe2+/black copper of 2/1 and 1 mol/L of sulfuric acid. Besides, the low-grade sample induced a significant consumption of H2SO4 due to the high presence of gangue and clays.

Some Chilean copper slag dumps from the nineteenth century still remain, without a proposed use that encourages recycling and reduces environmental impact. In this paper, the copper slag abandoned in landfills is proposed as a new building material. The slags studied were taken from Playa Negra and Púquios dumps, both located in the region of Atacama in northern Chile. Pozzolanic activity in lime and Portland cement systems, as well as the alkali activation in pastes with copper slag cured at different temperatures, was studied. The reactivity of the slag was measured using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), electrical conductivity and pH in aqueous suspension and Fourier Transform Infrared Spectroscopy (FTIR). Furthermore, copper slag-Portland cement mortars with the substitution of 25% (by weight) of cement by copper slag and alkali-activated slag mortars cured at 20 and 65 °C were made, to determine the compressive strength. The results indicate that the ancient copper slags studied have interesting binding properties for the construction sector.

ResumoEstudou-se a utilização da escória de cobre de uma fundição do Chile na fabricação de argamassas de cimento. A escória foi caracterizada através de análise quí-mica, mineralógica e granulométrica. Também foram usados diferentes padrões para se conhecerem alguns parâmetros importantes da escória e se fazerem os ensaios de compressão e de flexão das argamassas. Os resultados mostraram que as argamassas feitas com escória de cobre apresentaram maior resistência à compressão e à flexão que as preparadas com areia. O estudo conclui que esse resíduo metalúrgico poderia ser utilizado na construção civil. Palavras

RESUMEN:El objetivo de este trabajo es caracterizar 4 escorias de fundiciones de cobre del siglo XIX, procedentes de vertederos abandonados en la Región de Atacama -Chile, utilizando las técnicas de fluorescencia de rayos X (FRX), difracción de rayos X (DRX), microscopía electrónica de barrido (SEM), análisis de partículas por difracción láser (ADL), espectrometría infrarroja por transformadas de Fourier (FTIR) y análisis termogravimétrico (ATG). Las escorias de cobre estudiadas fueron clasificadas químicamente como escorias ácidas, con mayor contenido de SiO 2 (38 -49%) que de Fe 2 O 3 (18 -37%), y con una importante cantidad de CaO (8-26%) y Al 2 O 3 (5-8%). Su mineralogía y estructura es variada, presentando una de ellas una estructura amorfa y las tres restantes, una estructura cristalina con cierto carácter amorfo. Las fases minerales mayoritarias presentes en las escorias de cobre son diópsido, fayalita, magnetita, cristobalita y clinoferrosilita. Los niveles de calcio indicarían que las escorias poseen propiedades cementantes para ser utilizadas en materiales de construcción. Además, la importante cantidad de escoria disponible y el contenido de CuO (0,6 -1,2%) muestran que puede ser de interés como materia prima en la recuperación del metal. ABSTRACT: Characterization of chilean copper slag smelting nineteenth century. The aim of this work is to characterize four copper smelters slag nineteenth century, from abandoned landfills in Atacama Region -Chile, using the techniques of X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), particle analysis by laser diffraction (ADL), Fourier Transform Infrared Spectroscopy (FTIR) and thermogravimetric analysis (TGA). Copper slags studied were chemically classified as acidic slags, this slags presented higher SiO 2 content (38-49%) than Fe 2 O 3 (18-37%) and a significant amount of CaO (8-26%) and Al 2 O 3 (8.5%). Mineralogy and structure was varied, presenting one of them an amorphous structure and the remaining three, a crystalline structure with partially amorphous character. The majority mineral phases presented in the copper slag were diopside, fayalite, magnetite, cristobalite and clinoferrosilita. Calcium levels indicate that the slags could have cementitious properties for use as a binder in construction materials. Moreover, the significant amount of slag available and CuO content (0.6-1.2%) show that may be of interest as raw material for metal recovery.

In order to determine the exploitation potentiality of a kaolin deposit from Atacama in the north of Chile, two types of kaolin (K-1 and K-2) were characterized by XRD, XRF, SEM/EDXS, size distribution, whiteness and DSC. Kaolinite, quartz, muscovite and albite were recognized as main constituents of the ore deposit, and also a significant amount of impurities that negatively impacts on quality were detected. Results show that the low quality presented by the samples, especially K-2, impedes their industrial use as raw material and further mineral concentration processes are proposed. Finally, the results of thermal analysis confirm a conversion to metakaolin that could be the basis for an alternative processing route.

The use of copper slag as a partial substitute for cement in mortar preparation was studied. Copper slag samples were collected from three dumps in the Atacama Region (Northern Chile). Mortars of 40x40x160 mm (width, height, length) and curing times of 7, 28 and 90 days were used in mechanical testing. Tests were performed with 0% (control mortar), 5, 10, 15 and 20% copper slag as partial replacement of cement. The results of mechanical tests showed a gradual increase in compressive and flexural strength at 7, 28 and 90 days in mortars containing copper slag when compared with the control mortar. The major differences between the control and copper slag mortars are evident after 7 days, which indicates that the presence of slag in the blends has a retardant effect on the hardening process. On the other hand, at 90 days, compressive and flexural strength was very similar for both control mortar and mortars containing copper slag. Optimal compressive and flexural strength values are achieved with 5% of cement substitution by copper slag. The study concludes that the use of copper slag in mortars presents a viable alternative for partial cement replacement, and also contributes to mitigate adverse environmental effects of copper mining.

ResumoA escória de cobre é um resíduo metalúrgico massivo e reconhecido como um passivo ambiental. A geração anual de escória de cobre é de 24,6 milhões de toneladas, aproximadamente, e os principais impactos ambientais, derivados da disposição da escória, é o uso de grandes extensões de solo e a contaminação visual da paisagem. Nas últimas décadas, as escórias de cobre têm sido utilizadas na fabricação de concretos e argamassas de cimento. Nesse estudo, com o objetivo de verificar a influência do tipo de ligante na dureza final de argamassas, foram utilizados dois tipos de cimento: cimento normal e cimento de alta resistência. A escória de cobre foi caracterizada por análise química, mineralógica e granulométrica. Regras chilenas de construção foram utilizadas na metodologia aplicada para a determinação de alguns parâmetros importantes das escórias. Ensaios de resistência à compressão e flexão foram realizados em argamassas de cimento, em laboratórios especializados. Os resultados obtidos mostraram que as argamassas preparadas com escória de cobre e cimento normal apresentaram melhor resistência à compressão e flexão do que as argamassas preparadas com a areia normal, e os resultados obtidos com cimento de alta resistência inicial foram ainda melhores. Pode-se concluir, a partir desse trabalho, que a escória de cobre tem boas características mecânicas, para ser usada na fabricação de argamassas de cimento, constituindo-se em uma adequada alternativa para uso na indústria da construção. Palavras

Palabras clave: neumáticos usados, hormigón con fibras, valorización de residuos RESUMEN Los neumáticos fuera de uso se consideran residuos masivos y normalmente son abandonados en vertederos legales o ilegales. Su abandono se asocia con impactos medioambientales en el uso del suelo y la contaminación visual, entre otros. Por el contrario, su reciclado permite valorizar estos residuos al generar subproductos tales como gránulos de caucho, fibras de acero y fibras textiles para nuevas aplicaciones industriales. Diversos estudios reportan la utilización de fibras de caucho y de acero de neumáticos fuera de uso en hormigones. El objetivo de esta investigación fue evaluar y comparar la resistencia mecánica de un hormigón sin adición (testigo) a las edades de 7, 17 y 28 días, con hormigones con adición de fibra de acero comercial, fibras de caucho y fibras de acero de neumáticos fuera de uso. Las dosis utilizadas fueron 50 kg/m 3 en hormigones con fibra de acero comercial, 10.5 y 7 kg/m 3 en hormigones con fibras de caucho reciclado, y 50 y 35 kg/m 3 en hormigones con fibras de acero reciclado. Los resultados indicaron que los hormigones con adiciones de fibras de caucho y fibras de acero presentaron en todos los casos una leve disminución de la resistencia a la compresión respecto del testigo a la edad de 28 días. Por el contrario, los hormigones con adiciones de fibras de acero y fibras de caucho presentaron mejor resistencia a la flexo-tracción que el hormigón testigo, excepto el hormigón con dosis de 50 kg/m 3 de fibra de acero reciclado.