The re-processing of mine tailings to obtain critical raw materials (CRMs) could reduce the mining of new deposits as well as ensure the profitable use of the waste materials. Though, it requires ...large scale industrial installations and the development of specialized technologies to obtain CRMs. New investment in mining activities is an operation, engaging for considerable financial resources involved. The scale of such an endeavor makes a new mining activity a high-risk operation due to several uncertainties present. Therefore, there is an acute need to use new tools to assess the risk associated with the planning and development of new mining activities.
This study introduces a framework to evaluate the economic risk related to the re-processing of mine tailings to obtain CRMs. The framework, based on real options analysis (ROA), and sensitivity and uncertainty analysis, was applied to analyze the profitability of using mine tailings as a source of CRMs in the Chilean mining industry. The novelty of this approach consists in enabling the investment decision making including the uncertainties related to a novel investment mining project.
show that tailing storage facilities in Chile have some stocks of CRMs, like scandium, whose extraction could be profitable. For the data used, the results of uncertainty and sensitivity analyses show that capital expenditure has a more significant influence than the other variables. Therefore, for the case of mine tailings re-processing, it is essential to develop processes and technologies that enable lower capital expenses.
•Copper mine tailings contain considerable quantities of critical materials including rare earths.•Net present value is negative for mine tailings investments for scandium production.•Capital expenditure is the most influential variable in sensitivity analysis of net present value.•Scandium production is economically justified when option value is positive.
Antofagasta (Chile) is an arid region, and the climate is strongly influenced by the Atacama Desert, with few sources of fresh water. The pressure to use non-conventional water sources has boosted ...the construction of numerous desalination plants. High concentrations of secondary ions as calcium and magnesium cause problems in reverse osmosis plants and in other industries such as copper mining and cooling system.
Biomineralization process based on hydrolysis of urea has been described in a wide variety of bacterial species with diverse applications. The selection of ureolytic halotolerant bacteria from Atacama Salar and their ability to precipitate calcium and magnesium crystals in seawater is described. Besides crystal structure and morphology were determined by electron microscopy analysis and X-ray diffraction. When assessing the mineral precipitate ability, Rhodococcus erythropolis precipitates a ~95% soluble calcium and 8% magnesium. The analysis of crystals showed that correspond to ~12.69% monohydrocalcite, ~30.72% struvite and ~56.59% halite. These results demonstrate that the biomineralization by ureolytic bacteria in seawater has great potential for its application as a pretreatment to improve water quality for industrial processes.
•A new application for biomineralization is removal of calcium and magnesium ions from seawater as selective biodesalination•Twelve bacterial strains were identified from Atacama Desert with ureolytic activity precipitating calcite in seawater.•Rhodococcus erythropolis TN24F removed in just 7days 95% of soluble calcium and in 14days of bioassay the 8% magnesium ion.
The formation of minerals such as calcite and struvite through the hydrolysis of urea catalyzed by ureolytic bacteria is a simple and easy way to control mechanisms, which has been extensively ...explored with promising applications in various areas such as the improvement of cement and sandy materials. This review presents the detailed mechanism of the biominerals production by ureolytic bacteria and its applications to the wastewater, groundwater and seawater treatment. In addition, an interesting application is the use of these ureolytic bacteria in the removal of heavy metals and rare earths from groundwater, the removal of calcium and recovery of phosphate from wastewater, and its potential use as a tool for partial biodesalination of seawater and saline aquifers. Finally, we discuss the benefits of using biomineralization processes in water treatment as well as the challenges to be solved in order to reach a successful commercialization of this technology.
•Current and emerging technologies to remove calcium and magnesium ions are discussed.•A technology assessment to compare scale control technologies was conducted.•The energy consumption is the main ...challenge in technologies of scale control.
Calcium and magnesium ions are the major components of scaling in different water sources, especially seawater. Calcium and magnesium scale causes problems in various industrial operations such as reverse osmosis unit, heating unit of multi-stage flash distillation, concentration operation of copper-molybdenum mining industry, cooling water system of power generation industry, and water injection operation of oil and gas production. In general terms, scaling affects the operation performance that leads to increased production, as well as maintenance costs. The pH control, scale inhibitors, and nanofiltration membrane have been implemented by industrial operations to control scale. However, the drawbacks of these technologies may force to seek alternative technologies which could be potential alternatives for scale control.
This paper discusses the problems of calcium and magnesium scale affecting various industrial operations when seawater is used. It presents current technologies for scale control such as pH control, scale inhibitors, and nanofiltration. Moreover, the technology assessment (TA) was made to evaluate existing and emerging scale control approaches in the case of reverse osmosis (RO) process. The identification of the emerging technologies of scale control has been performed using bibliometric analysis. The comparison of the technologies was made using House of Quality (HOQ) matrix. The identified emerging technologies are: bioelectrochemical system, biomineralization, biosorbent, microbial desalination cells, step by step deposition and extraction technique, carbon dioxide as a precipitator, gas hydrate, ultrasonic crystallization, and capacitive deionization. The comparison of the technologies has shown that nanofiltration, as a common technology, could be an appropriate approach to ensure feasibility and efficiency of RO process, while emerging technology, microbial desalination cells, could become a potential alternative in the future.
The use of seawater in mining Cisternas, Luis A.; Gálvez, Edelmira D.
Mineral processing and extractive metallurgy review,
01/2018, Letnik:
39, Številka:
1
Journal Article
Recenzirano
This article reviews the use of seawater in mining with an emphasis on its use in Chile. The importance of the use of seawater in mining is highlighted in the introduction, then the main ...characteristics of seawater are reviewed, especially its potential effects on its use in mining. Subsequently, the consumption of seawater in Chile, especially in the regions located in the Atacama Desert, is analyzed based on statistics developed by Cochilco (Chilean Copper Commission). Later, the alternatives for the use of seawater and the distribution system are considered. The effect of seawater on the sulfide minerals flotation, the sulfide copper minerals leaching, and Caliche leaching is analyzed. We can conclude that the use of seawater has been increasing in Chile, which is already a reality, but there are challenges and opportunities that arise from the need to use seawater as a water resource.
Many regions around the world are suffering from water stress, and desalinated water and recycled water are seen as alternatives for meeting the water demand. However, high energy consumption and ...associated greenhouse gas emissions are some of the main environmental impacts. This is notable for many arid and semi-arid countries where desalination and water recycling are considered options for ensuring water resources availability. This research presents the incorporation of the quantification of greenhouse gas emissions generated during the operation of desalination and wastewater treatment plants in the assessment of water stress levels using the water stress indicator adopted by the 2030 Agenda for Sustainable Development. Chile was chosen as a case study, as it is a country where there is a considerable difference between the availability of conventional water sources and the water demand, and the electrical grid is fed mainly by fossil fuels. The methodology proposed allows calculating the indirect greenhouse gas emissions due to electrical consumption for the operation of desalination and wastewater treatment plants, and the direct greenhouse gas emissions coming from biological processes used in wastewater treatment plants. The results showed that Chilean arid climate zones will not experience water stress in the future at the regional level, mainly because of the installation of several desalination plants by 2030. Meanwhile, recycled water from the urban sector will slightly contribute to the reduction in the level of water stress in almost all Chilean regions by 2030. Moreover, desalination and wastewater treatment plant will contribute only between 0.34% and 0.75% of total greenhouse gas emitted in Chile by 2030. Therefore, the operation of these industrial systems for facing water scarcity problems in northern and central zones of Chile is a suitable alternative because it does not generate large environmental problems.
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•Water stress indicator is used for assessing water stress levels in Chile.•The use of desalinated and recycled water is considered in water stress assessment.•Quantification of greenhouse gas emissions are considered in water stress assessment.•Impacts of using nonconventional water sources to face water stress are presented.•Chile's water-scarce zones will not present water stress by 2030 at regional scale.
This work presents a multi-objective optimization approach to designing integrated water supply systems for the mining industry. The main goal is to estimate the total operational costs and ...greenhouse gas emissions from water supply systems. Chilean mining industry has been selected as a case study because of acute problem of water scarcity that it experiences. The current strategy to face the problem applied by the mining companies operating in Chile consists in building independent water supply systems that use ocean as the source of water. This solution is highly energy intensive, which is why the problem of water consumption is also a problem of energy consumption. The proposed optimization approach determines - from technical, economic and environmental perspective - the optimal topology of the system, optimal locations and sizes of water treatment plants, pumping stations, and pipelines. In addition, the analysis takes into account the eventual use of photovoltaic solar system in order to decrease greenhouse gas emissions. Our main findings have demonstrated that an integrated water supply system is always the best option from an economic and environmental point of view.
•A new optimization approach to designing integrated water supply systems is presented.•The trade-off between economic and environmental aspects of the system is assessed.•The results show that an integrated system is always the best option.
Effect of Seawater on Sulfide Ore Flotation: A Review Jeldres, Ricardo I.; Forbes, Liza; Cisternas, Luis A.
Mineral Processing and Extractive Metallurgy Review,
11/2016, Letnik:
37, Številka:
6
Journal Article, Book Review
Recenzirano
The flotation process in seawater is highly complex and multifaceted, wherein the chemistry is very different to that of pure water. The high saline environment compresses the electrical double ...layers resulting in (i) enhancement of the floatability for surfaces that are already hydrophobic; (ii) mitigation of the slime coatings; (iii) increase of the entrainment; (iv) reduction of the bubbles size; and (v) better froths stability. In parallel, the secondary ions present in seawater cause a colloidal precipitation and a strong buffering effect, which difficult the operation at high alkaline condition. The objective of this review is to present a summary of the current knowledge on the subject of seawater flotation processes, highlighting the copper sulphide ores flotation. This review includes a description of the underlying flotation mechanisms affected by the presence of saline water and seawater, as well as a more practical description of industrial flotation operations.
Multiphase systems are important in minerals processing, and usually include solid–solid and solid–fluid systems, such as in wet grinding, flotation, dewatering, and magnetic separation, among ...several other unit operations. In this paper, the current trends in the process system engineering tasks of modeling, design, and optimization in multiphase systems, are analyzed. Different scales of size and time are included, and therefore, the analysis includes modeling at the molecular level (molecular dynamic modeling) and unit operation level (e.g., computational fluid dynamic, CFD), and the application of optimization for the design of a plant. New strategies for the modeling, design, and optimization of multiphase systems are also included, with a strong focus on the application of artificial intelligence (AI) and the combination of experimentation and modeling with response surface methodology (RSM). The integration of different modeling techniques such as CFD with discrete element simulation (DEM) and response surface methodology (RSM) with artificial neural networks (ANN) is included. The paper finishes with tools to study the uncertainty, both epistemic and stochastic, based on uncertainty and global sensitivity analyses, which is present in all mineral processing operations. It is shown that all of these areas are very active and can help in the understanding, operation, design, and optimization of mineral processing that involves multiphase systems. Future needs, such as meso-scale modeling, are highlighted.
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