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Froth flotation is a widely used method for the concentration of sulfide minerals. The structure of the superficial froth is an indicator of the performance of froth flotation alongside with the operational conditions in which this process is carried out. The aim of this study is to explore how the different operational conditions that can be managed in a flotation plant could directly influence the observable characteristics of the superficial froth. For this purpose, a froth image database was created using a special laboratory cell, designed to emulate the conditions seen in an industrial flotation cell. The database contains 2250 images, distributed in 45 categories; each category has a specific combination of testing conditions, and the main visual characteristics are observed. It also includes a methodology used to assess the quality of each corresponding category. Dataset: doi.org/10.6084/m9.figshare.21437292 Dataset License: CC BY 4.0 [ABSTRACT FROM AUTHOR]

Comminution is the stage with the largest energy consumption in the mining process. Therefore, several pre-treatments have been proposed to reduce the energy requirements of this stage. This work analyzed the effect of a heating pre-treatment on the Bond index. A conventional heating pre-treatment was applied to a Chilean copper ore. The ore was heated to temperatures from 300 to 600 °C using a conventional furnace, resulting in a reduction of 19% in the Bond work index. Due to the pre-treatment, the mineral cracked in several areas. Microfracture and composition analyses of these areas confirmed that crack generation in the ore is due to the thermal stress produced by the pre-treatment. The fracture analysis explains the reduction in the Bond work index, since crack generation started at similar temperatures to those at which the reduction in the Bond work index was observed. In addition, the analysis also shows that micro-cracks occur between and through different phases, which may have an impact on mineral liberation. These results also show that, under a moderate high temperature, an important reduction in energy consumption can be obtained. [ABSTRACT FROM AUTHOR]

The effects of halophilic bacteria (Halobacillus sp. and Marinobacter sp.) on pyrite and chalcopyrite surface oxidation in artificial seawater are studied by electrochemical impedance spectroscopy (EIS) in conjunction with X-ray diffraction (XRD) and cyclic voltammetry analysis (CV), in order to explain the influence of these microorganisms on the minerals floatability. EIS analyses on pyrite electrodes suggest that biomaterial from both bacteria adheres to the mineral surface, which is reinforced by CV experiments as capacitive currents are promoted by both bacteria. Additionally, XRD analyses of pyrite samples after immersion in artificial seawater with and without bacteria indicate the formation of hematite on the mineral surface in the presence of Halobacillus sp., which together with the adherence of biomaterial could promote the depression of pyrite during flotation. On the other hand, EIS and CV analyses on chalcopyrite electrodes suggest that the adherence of Halobacillus sp. and Marinobacter sp. to the surface of the mineral have no significant effects on the kinetics of the chalcopyrite oxidation processes. These results together with XRD analyses of the chalcopyrite samples after immersion in artificial seawater with and without bacteria suggest that superficial sulphur might have a stronger influence on chalcopyrite flotability than the presence of bacteria. [ABSTRACT FROM AUTHOR]

Water and energy are essential requirements for mineral processing plants, and they can be either scarce or expensive. In the present paper, the implications of a remote water source location (typically the seashore) are analyzed in terms of a definition for the combined water and energy operational cost required to transport ore concentrate using long distance pipelines. A typical process route is defined to expose the relevance of key process variables, including source remoteness and water reclamation both from tailing storage facilities and thickeners. Both mass and energy balances have been made to give an estimation of specific energy consumptions for a typical large scale Chilean mineral processing operations, considering a number of realistic hydraulic design criteria to make a comparative analysis of different plant processing capacities. In the present cost function definition, an account has been made on whether the water is either makeup or has been recirculated on the plant, and a distinction has been made on whether tailings are conventional or thickened, which allowed to analyze the relevance of in-plant water recovery compared to water recovery from the tailing disposal site. This has allowed to express the cost of water in terms of the various energy cost terms, thus showing in this case that the cost of water is ultimately the cost of energy, and therefore all cost components become proportional to the unit cost of energy. A piecewise constant pipeline diameter analysis scheme has been defined to allow studying the implications of water recovery on widely different plant sizes. Results show that for fixed water recovery rates, increasing plant throughput tends to cause a decrease on the specific energy for water transport. On the other hand, for fixed pipeline diameters, increasing the throughput causes an increase on the specific energy consumption, but such increase rate becomes milder at higher throughput rates. This suggests the advantage of the existence of common makeup water supply systems for mining districts with more than one mineral processing plant. On the other hand, for constant pipeline diameters, increasing the water recovery from the tailing disposal site or from thickeners generates a decrease of water specific energy consumption, where in the case of the water recovery from the tailing disposal site such decrease rate becomes stronger with the amount of water recovered. Results also shows that, except for very high solid concentrations, water makeup costs dominate over recirculation ones, supporting that producing thickened tailings is a more efficient option than conventional ones in the sense of specific energy consumption, in spite of the additional energy costs due to slurry transport that this option implies. [ABSTRACT FROM AUTHOR]

• Geometallurgical modeling applied to mineral processing plant performance. • Ore blending in mineral processing plant is assessed using simulation. • Residence time distributions assessment for different plant configurations. Mineral processing plant performance depends on multiple factors, including the feed and the parameters to control the process. In this work, we show how to assess plant performance using geometallurgical modeling and dynamic simulation. Several models that describe comminution, classification, flotation, and residence time distribution (RTD) are implemented as modules and then connected to represent generic plant configurations. The estimation of the RTD is used to assess the ore blending generated within the plant through a methodology based on weighting the ore contribution at the plant discharge. Additionally, the RTD is used to display the ore permanence at different plant stages, which can be used as an operational input to anticipate the consequences of a perturbation in the feed. Different simulation scenarios are tested using synthetic data, including different plant configurations, time support for blending assessment, and ore feeding sequence. The results show that the simulation is sensitive to these attributes. Significant differences are detected in the generated product compositions when the plant configuration is changed. Also, distinct mine plans can be evaluated through simulation, predicting their processing performance. Therefore, the simulation tool developed can be used to evaluate real mineral processing operations and to test different operative strategies. [ABSTRACT FROM AUTHOR]

Acidithiobacillus ferrooxidans has been shown to be a good depressant of pyrite in freshwater and seawater flotation. However, the effect of these bacteria over copper-activated pyrite has not been studied. At the industrial scale, the activation of pyrite with copper is a common process that occurs because Cu 2 + ions, released from other minerals, react with pyrite. This is a problem because Cu 2 + ions facilitate the reaction of pyrite with the xanthate collectors, becoming hydrophobic and reaching the froth. In this study, microflotation experiments in a Hallimond tube were conducted to evaluate the depressant effect of A. ferrooxidans over non-activated and Cu-activated pyrite in freshwater and seawater flotation. The experiments were carried out at pH 4, 6, 8, 10 and 12 and pyrite was mixed with CuSO4 at 2.5 × 10 − 5 and 5 × 10 − 5 M in order to activate its surface. Considering the results obtained in the microflotation tests, it is possible to conclude that Acidithiobacillus ferrooxidans is able to depress non-activated and Cu-activated pyrite at the entire pH range studied (4–12) in freshwater. On the other hand, the use of bacteria in flotation with seawater proved to be effective to depress non-activated and Cu-activated pyrite at pH 8 and 10 with better results achieved at pH 10. At this pH, the non-activated pyrite recovery dropped from 96% to 15%, and the recovery of Cu-activated pyrite dropped from 95% to 32% when the activation was carried out at 2.5 × 10 − 5 M, and from 87% to 50% when the activation was conducted at 5 × 10 − 5 M of CuSO4. The XPS analysis showed that chalcopyrite and copper (II) hydroxide were formed on the pyrite surface when it is contacted with CuSO4. [ABSTRACT FROM AUTHOR]

Ore hardness plays a critical role in comminution circuits. Ore hardness is usually characterized at sample support in order to populate geometallurgical block models. However, the required attributes are not always available and suffer for lack of temporal resolution. We propose an operational relative-hardness definition and the use of real-time operational data to train a Long Short-Term Memory, a deep neural network architecture, to forecast the upcoming operational relative-hardness. We applied the proposed methodology on two SAG mill datasets, of one year period each. Results show accuracies above 80% on both SAG mills at a short upcoming period of times and around 1% of misclassifications between soft and hard characterization. The proposed application can be extended to any crushing and grinding equipment to forecast categorical attributes that are relevant to downstream processes. [ABSTRACT FROM AUTHOR]

Highlights • The rheology of magnetite tailings has been studied in relation to seawater content. • Several seawater/process water combinations have been used. • Seawater significantly affects the yield stress of tailings. • Yield stress is related to zeta potential. Abstract It is well known that seawater affects mineral beneficiation, especially in the presence of fine particles. In the present paper, the effect of seawater fraction on the rheology of unflocculated fine magnetite tailings has been studied. Slurry data has been interpreted as both Bingham and Herschel-Bulkley fluids. To relate the experimental results with surface physicochemical properties, zeta potential measurements have been performed to the samples. Results show that besides the well known result that the yield stress and Bingham viscosity have a strong dependency on the particle concentration, the yield stress has been found highly sensitive to the seawater fraction. In contrast, the plastic viscosity observed a comparatively weaker dependency on this variable. [ABSTRACT FROM AUTHOR]