Mining has occupied an important place in the Chilean economy since the 19th century and up to the present day. However, the oscillating cycles of economic booms and crises in the mining sector have left traces of industrial buildings from mining and copper metallurgy with unique characteristics. The objective of this article is to describe the materiality and origin of the construction system used in the ruins of a former nineteenth-century copper foundry located in the port of Caldera, in northern Chile. The ruins of the buildings show that the foundations and walls built with blocks of copper slag melted and molded in situ, was a construction technique brought by the English builders and metallurgists who arrived in the mining centers of Atacama, replicating the techniques used in English works, an activity that allowed the valorization of metallurgical waste.

La minería ha ocupado un sitial importante en la economía chilena desde el siglo XIX y hasta nuestros días. Sin embargo, los oscilantes ciclos de bonanzas y de crisis económicas del sector minero, han dejado vestigios de edificaciones industriales de la minería y la metalurgia del cobre de características muy singulares. El objetivo de este artículo es describir la materialidad y origen del sistema constructivo utilizado en las ruinas de una ex fundición de cobre del siglo XIX ubicada en el puerto de Caldera, en el norte chileno. Los vestigios de las edificaciones, muestran que los cimientos y muros construidos con bloques de escoria de cobre fundida y moldeada in situ, fue una técnica constructiva traída por los constructores y metalurgistas ingleses que arribaron a los centros mineros de Atacama, replicando las técnicas utilizadas en obras inglesas, actividad que permitió valorizar los residuos metalúrgicos.

Copper slag is considered a mining environmental liability and is usually deposited in landfills. However, some investigations have been oriented to their use in mortars and concretes. On the other hand, no studies have been reported on the use of copper slag from abandoned landfills of the 19th century in the design of asphalt pavements. In this study, the behaviour of hot asphalt mixtures containing copper slag from abandoned landfill in northern Chile, as a partial substitute for coarse aggregate was evaluated. For the design and control of bituminous pavement mixtures, the Marshall method was used. The parameters evaluated were density, % air voids in the mixture, % voids in the mineral aggregate, creep and stability. In addition, asphalt mixtures containing 4.5 to 6.0% were evaluated with increments of 0.5% asphalt for four types of mixtures with partial substitution of conventional aggregates by copper slag (0, 30, 50 and 70%, by weight). In conclusion, it can be pointed out that the mixture with 5% asphalt and 30% copper slag in replacement of the aggregate is the most suitable mixture and could be used in the design of asphalt mixtures for pavements. The use of copper slag from abandoned landfills in the manufacture of asphalt pavements, would contribute to improving environmental conditions, also decreasing the demand for aggregates in desert areas such as the Atacama Region in Chile.

La escoria de cobre se considera un pasivo ambiental minero y normalmente se deposita en vertederos. Sin embargo, algunas investigaciones se han orientado a su utilización en la fabricación de morteros y hormigones. Por otra parte, no se han reportado estudios sobre el uso de escorias de cobre de vertederos abandonados del siglo XIX en el diseño de pavimentos asfálticos. En este estudio se evaluó el comportamiento de mezclas asfálticas en caliente conteniendo escoria de cobre de un vertedero abandonado del norte de Chile, como un sustituto parcial del árido grueso. Para el diseño y control de mezclas de pavimento bituminoso se utilizó el método de Marshall evaluando la densidad, porcentaje de huecos de aire en la mezcla, porcentaje de vacíos en el agregado mineral, fluencia y estabilidad. Además, se evaluaron mezclas asfálticas conteniendo entre 4.5 a 6.0% de asfalto con incrementos de 0.5% para cuatro tipos de mezclas con sustitución parcial de árido grueso convencional por escoria de cobre (0, 30, 50 y 70%, en peso). Como conclusión se puede señalar que, la mezcla con 5% de asfalto y 30% de escoria de cobre en remplazo de los áridos, es la mezcla más adecuada y podría ser usada en el diseño de mezclas asfálticas para pavimentos. La utilización de escoria de cobre de vertederos abandonados en la fabricación de pavimentos asfálticos contribuiría a mejorar las condiciones ambientales disminuyendo, además, la demanda de áridos en zonas desérticas como la Región de Atacama en Chile.

RESUMEN Se estudió la flotación de escoria de cobre en una planta concentradora de la Región de Atacama, Chile. El estudio consistió en la caracterización física, química y mineralógica de la escoria de cobre, además de las pruebas preliminares de flotación. Este artículo se enfoca en la flotación industrial, la cual consistió en dos campañas de un año cada una (2016 y 2017). En la primera campaña se utilizó un circuito de flotación de escorias existente en la planta. Para la segunda campaña (2017), se utilizó un circuito de flotación de sulfuros, más una etapa adicional de limpieza mediante flotación columnar. Los resultados mostraron mejora en los parámetros metalúrgicos de la segunda campaña (incluyendo mejoras en capacidad de procesamiento, ley de concentrado de cobre y recuperación metalúrgica). De las campañas de flotación de escoria de cobre, se concluyó que es posible obtener un concentrado de cobre de calidad comercial, apto para su posterior procesamiento en una fundición. Esto mitiga ciertos impactos ambientales del procesamiento de cobre.

ABSTRACT Copper slag flotation was studied on an industrial scale at a concentrator plant in the region of Atacama, Chile. This study consisted of the physical, chemical, and mineralogical characterization of the copper slag, along with preliminary flotation tests. This article focuses on industrial flotation, which consisted of two one-year campaigns (2016 and 2017). The first campaign was carried out using an existing copper slag flotation circuit in the plant. During the second campaign (2017), a circuit for sulfide ore flotation with an additional columnar flotation cleaning stage was evaluated. Results showed an improvement in metallurgical parameters on the second campaign (including improvements in processing capacity, concentrate copper grade, and metallurgical recovery). From the industrial copper slag flotation campaigns, it was concluded that it is possible to obtain a commercial-quality copper concentrate, suitable for further processing in a copper smelter. This mitigates certain environmental impacts of copper processing.

ABSTRACT In the Atacama region of northern Chile, there are a large number of abandoned mines and dams with tailings and little flora development. Sarcocornia neei, a halophytic plant growing in Chilean coastal areas, is highly tolerant to contaminated soils associated with mine tailings. The potential for bioabsorption of heavy metals and arsenic and the substrate stabilization by this species was evaluated in soil experimentally contaminated with mine tailings from the Copiapó Valley. Sarcocornia neei grew well, although more slowly, in experimental soils containing mainly Fe, Cu and Mn. In an advanced vegetative development stage, S. neei roots were able to stabilize the contaminated experimental soils, agglomerating them in more than 80 % and extracting chemical elements from them. These characteristics are potentially useful for phytoremediation and reduction of contamination by fine-size particles from mine tailings and contaminated soils.

RESUMEN En la región de Atacama, en el norte de Chile, hay una gran cantidad de minas y depósitos de relaves abandonados con poco desarrollo de flora. Sarcocornia neei, una planta halófita que crece en zonas costeras de Chile, es altamente tolerante a los suelos contaminados asociados con relaves mineros. El potencial de esta especie para la bioabsorción de metales pesados y arsénico y la estabilización del sustrato se evaluó en suelo contaminado experimentalmente con relaves mineros del Valle de Copiapó. Sarcocornia neei creció bien, aunque más lentamente, en suelo conteniendo principalmente Fe, Cu y Mn. En etapa de desarrollo vegetativo avanzado, las raíces de S. neei fueron capaces de estabilizar los suelos experimentales contaminados, aglomerándolos en más de 80 % y extrayendo elementos químicos de ellos. Estas características son potencialmente útiles para la fitorremediación y reducción de la contaminación por partículas de tamaño fino, provenientes de relaves y suelos contaminados.

ABSTRACT 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.

ABSTRACT The Copiapó river basin, to the south of the Atacama desert, has a strong anthropic intervention due to mining, agricultural and urban activities. The presence of mining environmental tailings in the basin is relevant, mainly when they are close to watercourses and populated areas. In this work the relationship between the variations of copper, lead, mercury and arsenic concentrations related to the sediment transport dynamics along a year was studied. From five points along the Copiapó river, including areas of mining, agricultural and urban intervention, the sediments were analyzed for granulometry and chemical composition. The results show that the temporal variation of elements concentrations was proportionally inverse to the transport of the finest fraction of the sediment. This is related to changes in sediments transport, influenced by sporadic rains, snow melting, sediment supply from upstream sediments and wind events in areas with mining activity.

RESUMEN La cuenca del río Copiapó, al sur del desierto de Atacama, tiene una fuerte intervención antrópica debido a la actividad minera, agrícola y urbana. La presencia de pasivos ambientales mineros en la cuenca es relevante, ya que éstos se encuentran cerca de cursos de agua y zonas pobladas. En este trabajo se estudió la relación entre la variación de concentraciones de cobre, plomo, mercurio y arsénico con la dinámica de trasporte de sedimentos a lo largo de un año. Se analizó la granulometría y composición química de los sedimentos presentes en cinco puntos del río Copiapó, incluyendo zonas de intervención minera, agrícola y urbana. Los resultados muestran que la variación temporal de la concentración de los elementos analizados es inversamente proporcional al incremento de la transferencia de la fracción más fina de sedimento. Lo anterior se relaciona con cambios en el transporte de sedimentos, el cual está influido por lluvias esporádicas, deshielo, aporte de sedimentos desde aguas arriba y eventos eólicos en las zonas con actividad minera.

ABSTRACT Waste tires are considered to be massive trash and are usually abandoned in legal or illegal landfills. Their abandonment is associated with environmental impacts on land use and visual pollution, among others. Conversely, its recycling allows to valorize these residues by generating by-products such as rubber granules, steel fibers and textile fibers for new industrial applications. Several studies report the use of rubber and steel fibers of waste tires in concrete. The objective of this research was to compare the mechanical strength of concrete without the addition of tires residues (control group) at the ages of 7, 17 and 28 days, to concrete added with commercial steel fiber, and rubber and steel fibers from waste tires. The doses used were 50 kg/m3 in concrete with commercial steel fiber, 10.5 and 7 kg/m3 in concrete with recycled rubber granules, and 50 and 35 kg/m3 in concrete with recycled steel fibers. The results indicated that concretes with the addition of rubber and steel fibers showed in all cases a slight decrease in the compressive strength compared to the witness at the age of 28 days. Conversely, concrete with the addition of steel and rubber fibers presented better flexural strength than the witness concrete, except in the case of concrete with 50 kg/m3 of recycled steel fiber.

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/m3 en hormigones con fibra de acero comercial, 10.5 y 7 kg/m3 en hormigones con fibras de caucho reciclado, y 50 y 35 kg/m3 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/m3 de fibra de acero reciclado.

The Atacama Region presents cycles of water scarcity that affect both the population and the productive sectors, which demand huge amounts of drinking water for its development. In order to reduce the pressure on the water resource, it encourages the saving of drinking water and/or the reuse of sewage and industrial waters. In this context, the use of waste water from the brackish water purification processes is a good alternative to drinking water in the manufacture of mortars and concretes. The present study evaluates the mechanical behaviour of the concrete containing waste water generated in the processes of reverse osmosis and ion exchange. To do this, four types of water were characterized: drinking water (control), reverse osmosis waste water process used in the production of purified drinking water; waste water of both the ion exchange process and the reverse osmosis process, both from the Regional Hospital of Copiapó, Atacama, Chile. Subsequently, different samples of concrete containing the 4 types of water were manufactured and their resistance to compression at the ages of 7 and 28 days was evaluated. The results showed that in all cases, the concrete made with waste water, reached higher resistance to compression than the control sample. From this study, it can be concluded that the use of waste water in the manufacture of concrete, can be a convenient alternative for the construction in arid zones.

La Región de Atacama presenta ciclos de escasez hídrica que afectan tanto a la población como a los sectores productivos, los que demandan ingentes cantidades de agua potable para su desarrollo. Con el propósito de disminuir la presión sobre el recurso hídrico, se incentiva al ahorro del agua potable y/o la reutilización de aguas grises domiciliarias y aguas industriales. En este contexto, la utilización de agua de rechazo proveniente de los procesos de purificación de agua salobre, se presenta como una buena alternativa al agua potable en la fabricación de morteros y hormigones. El presente estudio evalúa el comportamiento mecánico del hormigón conteniendo agua de rechazo generada en los procesos de depuración por osmosis inversa e intercambio iónico. Para ello, se caracterizaron 4 tipos de agua: agua potable (control), agua de rechazo del proceso de osmosis inversa utilizado en la producción de agua purificada para la bebida; agua de rechazo tanto del proceso de intercambio iónico como del proceso de osmosis inversa, ambos del Hospital Regional de Copiapó, Atacama, Chile. Posteriormente, se fabricaron diferentes muestras de hormigón conteniendo los 4 tipos de agua y se evaluó su resistencia a la compresión a las edades de 7 y 28 días. Los resultados mostraron que, en todos los casos, los hormigones fabricados con agua de rechazo alcanzaron mayores resistencias a la compresión que la muestra control. De los resultados del estudio, se puede concluir que el uso de agua de rechazo en la fabricación de hormigones, puede ser una conveniente alternativa para la construcción en zonas áridas.

ABSTRACT In recent years, water scarcity in northern Chile has increased markedly, leading to an over exploitation of groundwater aquifers. In the construction sector, water is used in large quantities throughout the different activities of the construction projects, this fact makes essential to quantify the water consumption in order to know the real demand for water, and thus to have a clear and precise vision about the volumes of this resource which are used in the different activities of a construction project. In this study, the water consumption coefficients in relation to the different items corresponding to the construction of 219 homes and 2 multipurpose rooms were determined. For this purpose, the theoretical results of water demand obtained by means of calculations of the project, were compared with the results obtained in the real consumption of water in-situ. Results obtained for theoretical and real consumption of the tasks showed that the theoretical water volume to be used in the work was 10,946 m3, this value differs with the real volume of 16,283 m3 of water used in the project, i.e., it was used an additional volume of 5,337 m3. The latter implies an increase of 48.8 % in water consumption, if compared to the theoretical water volume. The main water consuming activities were the following: soil compaction, irrigation to control particles in suspension, curing of concretes and mortars, worker camp, manufacture of concrete and mortars. Within these activities, the one that presented a higher than expected consumption was the irrigation for the control of suspended particles, whose theoretical value was 3,936,000 m3 and the real consumption was 6,010,000 m3, that is 53% higher than the provided. Considering the results obtained in this study, it is possible to estimate that in the construction sector there is higher water consumption, in comparison with the theoretical demand. In this sense, it is necessary to develop detailed studies based in the actual water consumption that guarantee the sustainability of this resource in arid zones.

RESUMEN En los últimos años, la falta de agua en el norte de Chile se ha incrementado notoriamente, esto ha llevado a una sobreexplotación de los acuíferos subterráneos. En el sector de la construcción, el agua se utiliza en grandes cantidades en diferentes actividades propias del proyecto, por lo que resulta fundamental su cuantificación con el propósito de conocer la demanda real de agua, y de esta forma tener una visión clara y precisa sobre los volúmenes de agua que están siendo usados en diferentes partidas de una obra. En el presente estudio, la determinación de los coeficientes de consumo de agua se efectúa a partir de una serie de datos obtenidos en la construcción de 219 viviendas y 2 salas de multiuso. Para ello, se compararon los resultados teóricos de la demanda de agua, a través de cálculos del proyecto, con respecto al consumo real de agua in situ. A partir de la determinación del consumo teórico y real, los resultados mostraron que la cantidad teórica de agua que debía ser utilizada era de 10.946 m3, bastante diferente de la cantidad real de agua utilizada que fueron 16.283 m3. Así, en la obra se utilizaron 5.337 m3 adicionales, lo que representa un aumento en el consumo de agua con respecto al teórico del orden del 48,8 %. Las principales actividades consumidoras de agua fueron las siguientes: compactación del suelo, riego para control de partículas en suspensión, curado de hormigones y morteros, campamento de trabajadores, fabricación de hormigones y morteros. Dentro de estas actividades, la que presentó un consumo mayor del esperado, fue el riego para el control de partículas en suspensión, cuyo valor teórico fue 3.936.000 m3 y el consumo real de 6.010.000 m3, es decir, un 53% mayor al previsto. Teniendo en cuenta los resultados alcanzados en este estudio, es posible estimar que en el rubro de la construcción hay un consumo de agua bastante superior a la demanda teórica. En este sentido, se hace necesario el desarrollo de estudios detallados basados en consumos reales que garanticen la sustentabilidad de este recurso hídrico en zonas áridas.

Abstract 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.

Abstract This investigation addressed the evaluation of the use of copper tailings in the construction industry in order to reduce the impact on the environment. The evaluation was performed by a technical comparison between stucco mortars prepared with crushed conventional sand and with copper tailings sand. The best results were achieved with the stucco mortars containing tailings. The tailings presented a fine particles size distribution curve different from that suggested by the standard. The values of compressive strength, retentivity, and adherence in the stucco mortars prepared with copper tailings were much higher than those obtained with crushed sand. According to the results from this study, it can be concluded that the preparation of stucco mortars using copper tailings replacing conventional sand is a technically feasible alternative for the construction industry, presenting the benefit of mitigating the impact of disposal to the environment.

A 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.

Copper slag is a massive metallurgist waste. Annual production rises up to 24.6 million tons, approximately, and the main environmental impact derived from slag disposal is the usage of great soil extensions and the resulting visual contamination of the landscape. Along time, copper slag has been used in the manufacture of concrete and cement mortars. Thus, with the aim of verifying binder-type influence in the final hardness of mortars, two types of cement were used: regular cement and high initial resistance cement. Copper slag was characterized from the chemical, mineralogical and grading viewpoints. Official Chilean regulations were used in the applied methodology for the determination of some important slag parameters. Compression and flexural strength trials were carried out on cement mortars in specialized laboratories. The obtained results showed that mortars manufactured with copper slag presented a better resistance to compression and flexural strength than mortars manufactured with normal sand, and those made with high initial resistance cement were even better. It can be concluded from this work that copper slag offers optimal mechanical characteristics to be used in the manufacturing of cement mortars, becoming a sustainable and adequate alternative material for usage in the construction industry.

Estudou-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 química, 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.

The use of a Chilean copper smelter slag in the manufacture of cement mortars was studied. Copper slag was characterized from the chemical, mineralogical and size distribution point of view. In addition, different Chilean standards were used to determine some important parameters of the waste and to perform compression and flexural assays of the cement mortars. The results obtained showed that the mortars manufactured with copper slag present a higher resistance to compression and flexural than those manufactured with river sand. It is concluded that this metallurgical residue can be used in civil construction.