Browsing by Author "Vyhmeister, Eduardo"
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Item A combined photovoltaic and novel renewable energy system: An optimized techno-economic analysis for mining industry applications(01/04/2017) Vyhmeister, Eduardo; Muñoz, Cristina Aleixendri; Bermúdez, José Miguel; Pina Moya, Javier; Fúnez Guerra, Carlos; Rodríguez Mayor, Lourdes; Godoy Faúndez, Alex; Higueras, Pablo; Clemente-Jul, Carmen; Valdés-González, Héctor; Reyes-Bozo, LorenzoThe productivity of the mining industry in Chile, currently the main driver of Chilean economy, is closely tied to foreign demand for ores. Ore-processing is known for involving energy–intensive processes, such as comminution, concentrating and cathodic processes. As mining activities take place in the arid north of Chile, they are affected by water scarcity. Water shortage has forced the industry to pump desalinated seawater up to mining sites over 2000 m above sea level, further increasing electricity consumption. Given these energy needs, and the fact that electrical energy supply in the north of Chile is based on fossil fuels, it is important to consider the use of renewable energies as environment-friendly and economic alternatives. The aim of this work is to evaluate, by an optimized techno-economic analysis, the use of photovoltaic and a novel wind-based technology to supply at least 10% of the current and the predicted electrical energy requirements of the mining industry in the Antofagasta region. A combination of an optimization problem and technical evaluation was performed using Matlab to obtain the optimal number of solar and wind-based technology units in a case study. Total energy generation from a novel wind-based technology unit is 67,616 MWh/y, corresponding to 14.45·106 Nm3 (1298 t) of hydrogen and 7.41·106 Nm3(10,323 t) of oxygen after electrolytical transformation. Considering a 65% efficiency of the combined cycle fed with hydrogen and oxygen, 28,133 MWh/y of electrical energy would be obtained. For the cases studied the cost of energy from the combined system was estimated to be between 0.255 US$/kWh and 0.273 US$/kWh, slightly higher than the average energy regional cost. According to the analysis, the renewable energy system could be a sustainable alternative to supply economic green energy to the mining industry in Chile.Item Adsorption of biosolids and their main components on chalcopyrite, molybdenite and pyrite: Zeta potential and FTIR spectroscopy studies(2015) Reyes-Bozo, Lorenzo; Escudey, Mauricio; Vyhmeister, Eduardo; Higueras, Pablo; Godoy Faúndez, Alex; Salazar, José Luis; Valdés-González, Héctor; Wolf-Sepúlveda, German; Herrera-Urbina, RonaldoZeta potential measurements were used to assess the electrokinetic characteristics of chalcopyrite, molybdenite and pyrite in the presence of biosolids and their main components (humic acids, glucose and serum albumin) as well as a commercial collector (Aero 6697). Fourier transform infrared spectroscopy (FTIR) was then used to gain a deeper understanding of the interaction of these compounds with these sulfide minerals. It aims to achieve a better understanding of the surface chemistry of sulfide-water interfaces that improve froth flotation at industrial scale in the step of copper sulfide ore concentration. Zeta potential results show that hydrogen and hydroxide ions are potential determining ions for each sulfide mineral studied. The addition of 50 g/t biosolids or all the other chemicals used in this investigation shift the isoelectric point of chalcopyrite. Under the same conditions, only humic acid significantly affects the zeta potential of molybdenite, making it more negative in the pH range investigated, and shifting its isoelectric point about 6 pH units. These compounds seem to have a poor affinity with pyrite surfaces because their zeta potential is slightly modified. FTIR spectroscopy characterization shows that biosolids and their main components can interact with chalcopyrite, molydenite and pyrite surfaces through a complex mechanism involving chemical or physical linkages. The results reported here seem to indicate that biosolids may be used as new environment-friendly froth flotation agents to concentrate copper and molybdenum sulfide minerals. (C) 2015 Elsevier Ltd. All rights reserved.Item Greening Chilean copper mining operations through industrial ecology strategies(2014) Reyes-Bozo, Lorenzo; Godoy Faúndez, Alex; Herrera-Urbina, Ronaldo; Higueras, Pablo; Salazar, José Luis; Valdés-González, Héctor; Vyhmeister, Eduardo; Antizar-Ladislao, BlancaSawdust was used as cheap sorbent for the remediation of a diesel and oil fuel-contaminated mining soil whereas biosolids were evaluated as collectors and frothers in froth flotation of copper sulphide ores. The use of these waste materials in copper sulphide ore mining and mineral processing may have a positive impact on the cleaner production of copper from its natural raw sources and may decrease the deleterious effect that mining operations have on the environment. Mixtures of oil fuel contaminated mining soil and sawdust were treated in an aerobic reactor at 50.0% humidity for several days. A significant decrease (over 60.0%) of Volatile Organic Compounds (VOCs) content in these mixtures was obtained after one-month of treatment. Rougher flotation of copper sulphide ores using biosolids – from wastewater treatment plants – and humic acids – a component of biosolids – as collector and frother yielded a copper sulphide concentrate with a copper grade and copper recovery of 0.8% and 26.0%, and 3.5% and 29.7%, respectively. Biosolids and humic acids have shown to be potential candidates to partially substitute traditional organic chemicals used in industrial flotation of copper sulphide ores. This possibility opens up an alternative for greening copper sulphide ore flotation by using more environment-friendly flotation reagents. Based on these results, a conceptual model based on industrial ecology and cleaner production principles is proposed for greening the overall copper sulphide ore processing.Item Modeling and energy-based model predictive control of high pressure grinding roll(2019) Vyhmeister, Eduardo; Reyes-Bozo, Lorenzo; Rodriguez-Maecker, Roman; Fúnez-Guerra, Carlos; Cepeda-Vaca, Fernando; Valdés-González, HéctorEven though semiautogenous grinding mills and ball mills are normally used in grinding processes, the industry is driven to decrease cost by increasing efficiencies and decreasing energy consumption. High Pressure Grinding Rolls (HPGR) are seen as an energy-efficient alternative but their developments in modeling and control have received relatively little attention. In this work a model and a control scheme for HPGR is presented that considers the total energy consumed as one of the main controlled variable. First, the model was generated by using literature-reported information of a specific manufacturer and lithology. The dynamic representation of the treatment capacity, product granulometric distribution (reported as 80% percentile), compression energy, and rolling energy were considered as the most important model output variables. Second, model validation was performed with considerable positive results (based on assessment of estimation errors). Finally, the model was used to generate a multiple input multiple output control scheme. As result, it was observed that the model had a correct representation of the phenomena involved and that the peripheral velocity and pressure used in the HPGR are useful manipulated variables to control the energy consumed by the equipment in an MPC scheme.Item Use of humic substances in froth flotation processes(2019) Reyes-Bozo, Lorenzo; Vyhmeister, Eduardo; Godoy-Faúndez, Alex; Higueras, Pablo; Fúnez-Guerra, Carlos; Valdés-González, Héctor; Salazar, José Luis; Herrera-Urbina, RonaldoContinual growing demand for metals in regular and emerging markets has led to an increasing use of chemicals and reagents in ore processing. This trend force to incur in an increasing use of commodities which inevitable leads to higher operational costs and environmental concern. The chemicals and reagents used in flotation processes especially invoke high costs of handling and disposal due to their hazardous nature, but until now, few studies have been carried out to seek possible alternatives. In order to develop a cheaper and greener processes, these hazardous materials should be replaced by more sustainable products, by-products, or wastes generated by other industries. Biosolids, cheaper and greener than chemical frothers and collectors, have been tested successfully in flotation processes. Studies of removal rates and froth flotation kinetics have been carried out independently, nevertheless a deeper understanding of the tradeoffs involved between the rates and kinetics should be obtained. This work evaluates the use of different collectors (conventional collector (CC), biosolids (and their main components), and mixtures of CC and biosolids main components) in the froth flotation of copper sulfide ores. Tests were carried out in Denver Cells, at fixed collector, frother, and pH levels, in order to estimate metallurgical and kinetic parameters. In rougher flotation tests, biosolids show to be the most efficient non-CCs, achieving Cu recoveries of 64.1%. CC achieved 76.2% Cu recoveries while none of the pure biosolids main components achieved Cu recoveries over 60%. In the kinetics studies, only the partial replacement of CC (by 50% of Humic Acids (HAs) or biosolids) allowed a similar copper recovery once compared with CC (~81% Cu to be obtained with a fast kinetic constant of ~0.88 min−1). For molybdenum, partial replacement of CC produced better recovery and kinetics constants (k of 0.83 min−1 and R∞ of 66.10% for 50% CC - 50% HAs; k of 0.90 min−1 and R∞ of 61.79% for 50% CC - 50% biosolids). Results show that different combinations of biosolids - CC or HAs - CC could achieve optimal flotation conditions. As evaluated, an optimal combinations would allow considerable reductions in energy and chemical consumption.Item Vapor-Liquid equilibria modeling using gray-box neural networks as binary interaction parameters predictor(2017) Vyhmeister, Eduardo; Rodríguez-Pino, Jonathan; Reyes-Bozo, Lorenzo; Galleguillos-Pozo, Rosa; Valdés González, Héctor; Rodríguez-Maecker, RomanSimulations of vapor-liquid equilibrium (VLE) are widely used given their impact on the scale, design, and extrapolation of different operational units. However, due to a number of factors, it is almost impossible to experimentally study each of the VLE systems. VLE simulations can be developed using representations that are strongly dependent on the nature and interactions of the compounds forming mixtures. A model that helps in predicting these interactions would facilitate simulation processes. A Gray Box Neural Network Model (GNM) was created as Binary Interaction Parameters predictors (BIP), which are estimated using state variables and information from pure components. This information was used to predict VLE behavior in mixtures and ranges not used in the mathematical formulation. The GNM prediction capabilities (including temperature dependency) showed an error level lower than 5% and 20% for mixtures considered and not considered in the training data, respectively.