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Cisternas L.A.,University of Antofagasta | Cisternas L.A.,Centro de Investigacion Cientifico tecnologico para la Mineria | Lucay F.,Centro de Investigacion Cientifico tecnologico para la Mineria | Galvez E.D.,Centro de Investigacion Cientifico tecnologico para la Mineria | Galvez E.D.,Catolica del Norte University
Minerals Engineering | Year: 2014

Different objective functions have been used in the design of concentration plants. The frequently used functions correspond to the maximization of revenue or profit. However, there is no study examining the effect of the type of objective function on the design of these plants. This manuscript analyzes the effect of various objective functions, including the maximization of profits, the return on investment and the net present worth and the minimization of the payback period, among other functions. Additionally, the procedure for a flotation circuit design is presented that is based on a flexible superstructure, where the designer can choose the set of alternatives. Two cases were considered: the equipment design for a given circuit structure and the circuit structure design given the equipment. The generated models correspond to mixed integer nonlinear programming and nonlinear programming problems. The results indicate that the objective function has a significant effect on the obtained solution, as well as the concentration circuit structure. © 2013 Elsevier Ltd. All rights reserved. Source


Moreno P.A.,Diego Portales University | Aral H.,CSIRO | Cuevas J.,Centro de Investigacion Cientifico tecnologico para la Mineria | Monardes A.,Las Cenizas Mining Group | And 3 more authors.
Minerals Engineering | Year: 2011

Las Luces is a copper-molybdenum beneficiation plant in Taltal (Chile), owned by the Las Cenizas Mining Group (Grupo Minero Las Cenizas) of Chile. The plant comprised of conventional crushing, grinding and flotation facilities. Las Luces has treated 720,000 tpa ore since 1995. This ore was supplied from Las Cenizas' own underground mines operating in the area. Seawater is brought to the plant from a distance of 7 km and pumped to an altitude of 178 m. In the Las Luces plant, seawater is mixed with tailings dam water in the Industrial Storage Pond. The mixed water is used in the grinding and flotation circuits. The Las Luces beneficiation plant has been successfully using seawater for over 15 years through a clever water recirculation scheme. The Las Luces plant is unusual in the sense that it has operated during this time without the use of any fresh water. Analytical data show that the dissolved salt content of the process water has increased from 36.0 g/L to 46.4 g/L or 0.7 g/L/year. Calculations suggest that this increase is largely due to solar evaporation where the evaporation rate reaches 50 m3/hectare/day. In Las Luces, the evaporation related water losses amount to 237 megalitres/year or a loss of approximately 69 days of seawater pumping to the Industrial Storage Pond. Based on this finding Las Cenizas is now investigating options to minimise the loss of water to evaporation. © 2010 Elsevier Inc. All rights reserved. Source


Jamett N.E.,University of Antofagasta | Vielma J.P.,University of Pittsburgh | Cisternas L.A.,University of Antofagasta | Cisternas L.A.,Centro de Investigacion Cientifico tecnologico para la Mineria
Computer Aided Chemical Engineering | Year: 2012

The objective of the present study was to develop a procedure for flotation circuit design that accounts for uncertainty and water efficiency. The design process considers two stages: 1) optimal process design without considering water consumption and 2) efficient use of water considering property integration.For the flotation circuit design, we applied stochastic programming. In the optimization problem, it is desired to find the optimal configuration, equipment design and operational conditions of a circuit with multiple stages (rougher, scavenger, cleaner). The problem includes uncertainty in the feed composition and in the metal price. Each uncertain parameter is characterized probabilistically using scenarios with different occurrence probabilities. Then, considering the solutions to different scenarios, property integration is used to design the water integration system. Three properties are included: pH, oxygen concentration, and conductivity.The application of the procedure to an example shows that including uncertainty in the design process can be useful for finding better designs. The property integration method can be extended for use in mineral processing. The novelty of this work is the integration of both methodologies and the application of these tools to mineral processing. © 2012 Elsevier B.V. Source


Taboada M.E.,University of Antofagasta | Hernandez P.C.,University of Antofagasta | Galleguillos H.R.,University of Antofagasta | Flores E.K.,Centro de Investigacion Cientifico tecnologico para la Mineria | Graber T.A.,University of Antofagasta
Hydrometallurgy | Year: 2012

Nowadays, the recovery of sodium nitrate through leaching caliche minerals with seawater is an industrial alternative due to scarce water resources, especially in desert areas. With a view to industrial applications, we determined the density, refraction index, ionic conductivity and viscosity of unsaturated solutions of the sodium nitrate + seawater system (seawater: 3.5% salinity) at six temperatures (298.15 to 323.15) K for different molalities in the range of (1 to 11) m. Data from saturation concentrations of the system at the same temperatures were determined. Property data were compared to the sodium nitrate + freshwater system. The experimental data on density, viscosity, and refraction index were correlated using the Othmer rule. The conductivity data were analyzed with the Casteel-Amis equation. Solubility, density, refraction index, ionic conductivity and viscosity of caliche mineral + seawater and caliche mineral + freshwater were measured at the same temperatures. The properties of caliche measured in the seawater system are greater than those in the pure water system, with an average difference of 1.30% with respect to seawater for density values, 0.23% for refraction index values, 2.42% for ionic conductivity values and 4.25% for viscosity values. © 2011 Elsevier B.V. All rights reserved. Source


Montenegro M.R.,University of Antofagasta | Galvez E.D.,Centro de Investigacion Cientifico tecnologico para la Mineria | Cisternas L.A.,University of Antofagasta
International Journal of Mineral Processing | Year: 2015

This paper analyzes the effect of uncertainty in the recovery of each concentration stage on the global recovery and concentrate grade. The uncertainties are represented by normal, uniform and triangular probability distribution functions (PDFs). The case studies include the uncertainty in the recovery of each stage separately and simultaneously across all of the stages with different standard deviation levels. A total of 2880 cases were studied, which corresponded with twelve circuits, three distribution functions and 84 different combinations with standard deviations in the stage recoveries. For each case, 2000 simulations were performed, with an overall simulation total of 5.76 million. Among the conclusions obtained in this work are the following: 1) The shape of the distribution function in the output variables is dependent on the input distribution function, the concentration circuit and the uncertainty level; 2) when the recovery of a single stage is represented by a PDF, the other stage recoveries are assigned a deterministic value then the type of the PDF obtained for the global recovery is similar to the input distribution; 3) when considering uncertainty in several stages simultaneously, the resulting PDF type usually is not the same PDF type observed for the input variables; and 4) the circuit structure affects more than the stage recoveries in the analysis of the global recovery and concentrate grade. © 2015 Elsevier B.V. All rights reserved. Source

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