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Oxidized black copper ores are known for their difficulty in dissolving their components of interest through conventional methods. This is due to its non-crystalline and amorphous structure. Among these minerals, copper pitch and copper wad are of great interest because of their considerable concentrations of copper and manganese. Currently, these...
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... pixel retains its elementary and BSE brightness information, which allows subsequent o✏ine data processing. Through software, customized filters are generated that quantify the ore and gangue species, mineral release, associations between inorganic phases, classifying particles according to criteria of shape, size, texture, etc. Figure 1 shows the chemical species to black oxides using QEMSCAN. ...
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In this study, electric field and ball milling were used to leach Mn²⁺ from low-grade pyrolusite (LGP). The effects of current density, reaction time, reaction temperature, ball-to-powder weight ratio, and ball milling time on the leaching efficiency of Mn²⁺ from LGP as well as the leaching mechanism were systematically studied. The results showed...
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... In the same vein, the addition of chlorides has also been studied to dissolve black coppers [29][30][31][32]. Thus, Torres and co-workers [33] published the use of chloride and ferrous ions to leach black copper ore. The result shows a poor copper recovery with only NaCl and sulfuric acid. ...
Although the importance of black copper ores is well established, many topics remain to be studied. This manuscript describes the efforts to improve copper recovery from refractory ores on a pilot scale. Preliminary tests provided the water dose to form a stable and compact agglomerate of 89 L per ton of ore and an acid dosage of 40 kg per ton of ore. The column leaching method resulted in an effluent with 1.63 g/L Cu, a pH of 1.04, and a redox potential of 675 mV (average). Despite the similarities observed in the results, reductant agents were essential to dissolve the MnO4 present in the black copper ore. Thus, the best Mn extraction results were 67.7% using the MnO2:FeSO4 ratio of 1:3. Additionally, the kinetics of leaching are slower than in an industrial operation. The copper ore under study required more than 65 days of leaching to reach the maximum copper recovery. Finally, the total recovery of copper (including washing and resting time) indicates that the maximum value was reached for ore pretreated with NaCl, H2SO4, and FeSO4, concluding that the use of agents favored leaching.
... This commodity is very important for the economy of various countries, for example, in Chile, copper mining contributes 10% of the gross domestic product (GDP) [3,4]. However, large-scale copper mining currently faces a number of challenges, such as decreases in mineral grades at the land surface [5][6][7][8], excessive increases in production to compensate for low ore grades [5], increase in environmental liabilities due to increased production [9][10][11], emission of polluting gases [12,13] and water scarcity in arid areas where copper mining is carried out [14][15][16][17][18]. Then, despite that hydrometallurgical processes are less polluting in general than pyrometallurgical processes, they have not been able to be profitable for the treatment of primary copper sulphides, therefore, there is a constant search for optimization of copper recoveries through flotation processes, in addition to reducing the consumption of groundwater in them. ...
The flotation of minerals is a multivariate physicochemical process that consists of applying the affinity of some mineral particles to the air, and also the affinity of other mineral particles for water, with the aim of obtaining a commercial product called concentrate, in addition to nonvaluable minerals called gangues. The flotation circuits, in charge of enriching the concentrate, generally consist of 3 stages, rougher, cleaner, and scavenger, which are made up of one or more cells, either in series or in parallel, depending on the architecture of the operational circuit. In this research, a local sensitivity analysis is developed for studying the behaviour of the stages that compose different flotation circuits. It is evaluated the concentrate grade quantifying the effect that circumstantial alteration has in the transfer rate of the concentration stages. The sensitivity analysis allows identify operation conditions that optimizing the concentrations offered by the flotation circuits. The results indicate that in simple circuits, the greatest impact on the concentration corresponds to rougher and cleaner cells, while in complex circuits (with additional cell banks), the sensitization of the rougher and cleaner cells, along with the early stages of the cleaner–scavenger cells have a greater impact on concentrate grade.
... important for the economy of various countries, like Chile, where mining copper contributes around 10% of the gross domestic product (GDP) [2,3]. Large copper mining currently faces several challenges, such as decreases in ore grades [4][5][6][7], excessive increases in production to compensate for low grades [4], increases in environmental liabilities such as high generation of tailings [8][9][10], emission of polluting gases [11,12] and water scarcity in arid zones [13][14][15][16][17]. Considering the above, there is a constant search of generation of models and/or algorithms for optimization of production processes, to improve the development of mineral processing in a sustainable way, increasing the recoveries of valuable minerals, reducing water consumption, limiting the impact on the environment, and adding the greatest possible value to stakeholders. ...
The volatility of the price of commodities generates the need for copper mining to control costs and make production processes more efficient. In this context, it is not possible to have real control over the productive indicators if it does not know the logistics of the processes, or you do not have a clear idea of the impacts of the variables or operational parameters on the dependent variables or responses. The present work aims to describe the production process for the leaching of secondary copper sulphides by means of heap leaching. This study focused on the search for theoretical relationships that define the behavior of copper recovery and the derivation of an analytical model that explains the response, developing a model capable of assertively representing the reality of the extractive process.
... On the contrary, the particle size decreased because the particles blocked the pores and compressed the mineral heap [81]. It is known that clays tend to have a very fine granulometry, which, according to many researchers [64,[82][83][84], can be decisive for an agglomeration, considering a proportion of fines smaller than a 50-75 mm size fraction. While grinding the ore to a smaller particle size often increases copper recovery at any given time [85], the benefit conferred by the treatment leads to higher acid consumption and energy, as well as the presence of more fine particles in the pile that can decrease its permeability. ...
... The precipitation of iron generates jarosite at a On the contrary, the particle size decreased because the particles blocked the pores and compressed the mineral heap [81]. It is known that clays tend to have a very fine granulometry, which, according to many researchers [64,[82][83][84], can be decisive for an agglomeration, considering a proportion of fines smaller than a 50-75 mm size fraction. While grinding the ore to a smaller particle size often increases copper recovery at any given time [85], the benefit conferred by the treatment leads to higher acid consumption and energy, as well as the presence of more fine particles in the pile that can decrease its permeability. ...
Heap leaching is a firm extractive metallurgical technology facilitating the economical processing of different kinds of low-grade ores that are otherwise not exploited. Nevertheless, regardless of much development since it was first used, the process advantages are restricted by low recoveries and long extraction times. It is becoming progressively clear that the selection of heap leaching as an appropriate technology to process a specific mineral resource that is both environmentally sound and economically feasible very much relies on having an ample understanding of the essential underlying mechanisms of the processes and how they interrelate with the specific mineralogy of the ore body under concern. This paper provides a critical overview of the role of gangues and clays minerals as rate-limiting factors in copper heap leaching operations. We aim to assess and deliver detailed descriptions and discussions on the relations between different gangues and clays minerals and their impacts on the operational parameters and chemical dynamics in the copper heap leaching processes.
... This has forced to increase production levels through mineral processing, which bring polluting minerals such as As, where the most common mineralogical species associated with toxic impurities present in copper concentrates are enargite (Cu 3 AsS 4 ), arsenopyrite (FeAsS), rejalgar (AsS), tennantite (Cu 12 As 4 S 13 ), tetrahedrite (Cu 1 2Sb 14 S 13 ), and famatinite (Cu 3 SbS 4 ) [10], which in pyrometallurgical processes is released into the atmosphere [11]. For this reason, it is necessary to generate new options to overcome an eventual stagnation of the growth capacity in mining, considering the significant challenges faced by the industry [12]. Actually, the development and utilization of mineral resources may not lead to serious arsenic pollution; however, when the intensity of exploitation and utilization of mineral resources increase, the problem of arsenic contamination may worsen if the enterprise lacks the motivation and means of arsenic recovery. ...
The conversion of arsenic-containing waste residues into arsenic matte can be an important direction for arsenic treatment. In this paper, different parts of factory samples were first taken for study, and it was found that the leaching amount of arsenic at the chilling layer is noticeably low. Then, the effects of the cooling rate on the phase, microstructure, and chemical compositions and the subsequent toxicity leaching of the arsenic matte were studied. The results show that the alloy structure was obviously refined and the cavity size was also significantly reduced with an increase in cooling rate. Many large-strip FeS and arsenic-containing iron solid solutions were embedded in the matrix (Fe2As) of the furnace-cooled and air-cooled samples; additionally, the Fe–As–S phase was probably caused by an insufficient phase separation of FeS from Fe2As in the rapid cooling process of die cooling and water cooling. FeS in the factory samples was dissolved in the leaching solution, while Fe2As could resist the corrosion of the leaching solution; therefore, it was speculated that the dissolution of arsenic was caused by the dissolution of FeS. The leaching mechanism was also discussed in this paper.
Graphic Abstract
The cooling rate affects phase, microstructure, and chemical compositions and toxicity leaching of the arsenic matte, which speculated that the dissolution of arsenic was caused by the dissolution of FeS
... The mining industry in Chile is constantly growing [1][2][3][4] . Historically, Chile has traded copper, this commodity being the main economic income contributing approximately 10 % of the gross domestic product (GDP) [5]. ...
Lithium has become a metal of enormous interest worldwide. The extensive use of recharge-able batteries for a range of applications has pushed for rapid growth in demand for lithium carbonate. This compound is produced by crystallization, by reaction with lithium chloride (in solution) and by adding sodium carbonate. Low sedimentation rates in the evaporation pools present a problem in the crystallization process. For this reason, in this work, mineral sedimen-tation tests were carried out with the use of two flocculant types with different ionic charges. The tests were carried out at a laboratory level using different dosages for each flocculant and measurements were performed to obtain the increase in the content of solids in the sediment. The anionic flocculant had better performance as compared to that of the cationic flocculant, increasing the sedimentation rate of lithium carbonate by up to 6.5. However, similar solids contents were obtained with the use of the cationic flocculant at 3.5 times lower dosage making it the flocculant of choice regarding the economic point of view.
... Due to the decrease in copper grades in the earth's crust, mining countries such as Chile have been forced to change their production systems, which were mainly based on copper sulfides treated by froth flotation methods [1][2][3]. New alternatives are sought, such as the extraction of other elements such as copper ore byproducts (black copper minerals), waste generated by the industry, and even the exploitation of sea resources (manganese nodules), which has become a promising solution [4,5]. ...
... Minerals with high MnO 2 contents (such as the ones above) have proven to be refractory to conventional leaching processes. Thus, to dissolve marine nodules it is necessary to work at low redox potential values [3,20,21]. Bafghi et al. [21] used sponge iron in a manganese nodule study. They evaluated different MnO 2 /Fe ratios and H 2 SO 4 particle sizes and concentrations. ...
... The authors found that when an Fe 3 O 4 /MnO 2 ratio of 2/1 or higher is used, other variables (H 2 SO 4 concentration, particle size, agitation speed, leaching time) are irrelevant when obtaining Mn dissolutions of around 80%. There are few studies on black copper minerals, and recent studies report Cu and Mn recovery when Fe-reducing agents are added [3,20,24]. Benavente et al. [24] added ferrous ions to acid in order to reduce leaching of black copper minerals and found that the dissolution of MnO2 immediately promoted Cu dissolution in black copper minerals. Pérez et al. [20] proved that the Fe 3 O 4 in tailings can be an efficient reducing agent of MnO 2 in black copper minerals when working with high concentrations, but showed lower dissolution kinetics regarding ferrous ions. ...
The low grade of copper deposits and the use of the froth flotation process have caused excessive tailing production. In recent years, experts have looked for new alternative methods to improve this situation. Black copper minerals are abundant resources not exploited by large-scale copper mining and possess high Mn concentrations. On the other hand, manganese nodules are submarine resources and show high concentrations of Cu, Ni, Fe, and, mainly, Mn. However, both mineral resources are refractory to conventional leaching processes, and so a reducing agent is necessary for their treatment. We studied the use of tailings obtained from the flotation of foundry slags with a high content of Fe3O4 as reducing agents at different MnO2/tailings ratios and H2SO4 concentrations. Mn dissolution was compared in marine nodule and black copper minerals samples. It was found that higher Mn dissolutions are obtained from marine nodules, likely due to the acid consumption created by Cu dissolution from black copper minerals. The remnant elements in manganese nodules were leached under an oxidant condition.
... The intensive exploitation and the decrease in copper deposits' grades will cause a shortage of oxidized copper resources in Chile [1][2][3]. It is expected that copper production by hydrometallurgical methods will go from 28.8% in 2017 to 11.6% by 2029, while the copper that is processed by pyrometallurgical operations should increase from 71.2% to 88.4% [4]. ...
This review aims to understand the environmental impact that tailings produce on the land and marine ecosystem. Issues related to flora, fauna, and the environment are revised. In the first instance, the origin of the treatment and disposal of marine mining waste in Chile and other countries is studied. The importance of tailings’ valuable elements is analyzed through mineralogy, chemical composition, and oceanographic interactions. Several tailings’ treatments seek to recover valuable minerals and mitigate environmental impacts through leaching, bioleaching, and flotation methods. The analysis was complemented with the particular legislative framework for every country, highlighting those with formal regulations for the disposal of tailings in a marine environment. The available registry on flora and fauna affected by the discharge of toxic metals is explored. As a study case, the “Playa Verde” project is detailed, which recovers copper from marine tailings, and uses phytoremediation to neutralize toxic metals. Countries must regularize the disposal of marine tailings due to the significant impact on the marine ecosystem. The implementation of new technologies is necessary to recover valuable elements and reduce mining waste.
... Black copper minerals are abundant in Chile, being present in large deposits such as: Mina sur Chuquicamata, Damiana in El Salvador, Lomas Bayas Spence, and El Tesoro and Huanquintipa in Collahuasi [16]. Even though these minerals contain considerable amounts of Cu and Mn [17], they are not commonly incorporated in the leach pads, being considered waste [18]. This is due to its amorphous, which prevents treating these mineral resources by means of conventional hydrometallurgical processes [16]. ...
... There are few studies that investigated leaching of black copper minerals [16][17][18][19]. In the investigations carried out by Benavente et al., [18] and Pérez et al., [16] it was discovered that working in an acid-reducing leaching favors dissolution of MnO2, thus favoring the extraction of copper. ...
... In the investigations carried out by Benavente et al., [18] and Pérez et al., [16] it was discovered that working in an acid-reducing leaching favors dissolution of MnO2, thus favoring the extraction of copper. Subsequently, Torres et al., [17] demonstrated that it is possible to considerably increase concentrations of Cu and Mn in solutions obtained from black copper in short periods of time (20 min) when working in stirred reactors and carrying out pre-treatment processes (agglomeration and curing) by adding a reducing agent (NaCl in that study). Furthermore, it should be noted that various studies have been carried out with the aim of MnO2 dissolution from manganese nodules [20][21][22][23][24][25][26][27][28], which provided multiple alternatives for extraction of Mn and Cu from black copper, as they have are similarly processed in leaching systems. ...
Currently, there is a large amount of mineral resources not being exploited in large copper mining, a clear example is black copper minerals. These resources are generally not incorporated into the extraction circuits or are not treated, either in stocks, leach pads, or debris. These exotic minerals have considerable amounts of Cu and Mn, which represent a commercial attraction. They are refractory to conventional leaching processes, therefore, for their treatment, the use of reducing agents is necessary to be able to dissolve the MnO2 present in them, which in turn allows Cu extraction. In this research, a comparative study is presented between two iron reducing agents (Fe2+ y Fe0) for the dissolution of Cu and Mn from a black copper mineral in an acidic medium, in addition, a previous pre-treatment process will be carried out (agglomerate and cure) adding NaCl to favour the reduction of MnO2. Finally, it was discovered that there is a higher kinetics of dissolution of Cu and Mn when working with Fe0 in short periods of time, although similar extractions of both elements are obtained in prolonged times. While carrying out a pre-treatment process adding NaCl, it allows to increase Cu and Mn extractions, allowing to obtain high solutions in short periods of time (30 min).
... (2) Subsequently, Torres et al. [21] developed a study to dissolve copper and manganese from pure black copper ore. In this study, pretreatment tests for agglomerate and curing by adding sulfuric acid and sodium chloride were carried out, followed by a leaching process with a reducing agent (Fe 2+ ) and standard condition (without reducing agent). ...
... For Cu and Mn dissolution from black coppers with Fe 2+ and NaCl in an acidic medium, the following reactions are proposed [21]: ...
... Chlorides are commonly used as an oxidizing agent for the extraction of Cu from oxidized and sulfided copper ores [22,23]. However, being in direct contact for prolonged periods, it can act as a reducing agent for MnO 2 [21]. Wang and Zou [24] reported standard redox potentials for the reduction of MnO 2 and chloride ions of Mn 3 O 4 /Mn 2+ = 1.76 V and Cl 2 /Cl − = 1.39 V, respectively. ...
Black coppers are mineraloids with a high content of Cu and Mn. These have an amorphous crystalline structure that makes them refractory to conventional leaching processes. For this reason, these mineral resources are not incorporated in industrial leaching heap processes and are taken to dumps. In the present study, an agglomerate pretreatment process incorporating NaCl is evaluated, and a curing stage, followed by acid-reducing leaching for Cu and Mn dissolution from a high-grade black copper mineral. For this, an experimental design was developed both to evaluate the impact of the dependent variables on the response, to generate analytical models that represent the copper and manganese recoveries under the set of sampled conditions. The models indicate that the curing time and the NaCl concentration have a primary effect on the recovery of both elements. In contrast, the optimization model suggests that the optimal operating levels are reached at relatively high levels of time (>130 h) and of NaCl concentration (>22 kg/t).
