Search

This study investigates the gold leaching potential of amino acids, focusing on glycine, alanine, and histidine, under various conditions. Results reveal that under alkaline environments, amino acids exhibit gold solubility, with glycine demonstrating superior efficacy compared to alanine and histidine. Strong oxidants like potassium permanganate enhance glycine-induced gold leaching, albeit with partial glycine decomposition. Notably, increasing glycine concentration beyond 0.05 M proves counterproductive. Electrochemical tests affirm that strong alkalinity fosters gold dissolution, with glycine's dissolution capability peaking at 0.05 M concentration. Conversely, at 0.1 M, glycine's dissolution efficacy diminishes. At a pH of 13, glycine achieved a gold leaching rate of 84.36% from gold-containing electronic waste. These findings underscore the importance of controlling amino acid concentrations in optimizing gold leaching processes, particularly favoring heap leaching over agitated methods. HIGHLIGHTS: Glycine effectively leaches gold at pH 13, achieving 84.36% leaching rate from electronic waste. Optimal leaching with 0.05 M glycine and potassium permanganate; higher glycine concentration can hinder process. Electrochemical tests confirm strong alkalinity enhances gold dissolution; suitable for heap leaching. [ABSTRACT FROM AUTHOR]

Kazakhstan has exhibited consistent growth in gold production and is currently ranked among the top ten leading countries in the field. This article provides an overview of the development of heap leaching technology for extracting gold from oxidized ores in Kazakhstan. Key factors influencing the efficiency of the heap leaching process are discussed, including the mineralogical composition of the ores, the particle size of the gold, the presence of associated minerals, and the challenges posed by leaching in harsh climatic conditions. The main characteristics of Kazakhstan’s heap leaching plants are presented. A comparative analysis is conducted with global practices, including those in the USA, Canada, China, Russia, Uzbekistan, and other countries. This analysis covers the main stages of the process: ore preparation, gold recovery from pregnant solutions through cementation, adsorption onto activated carbon and ion-exchange resins, desorption, and sorbent regeneration. The advantages and disadvantages of different methods for extracting gold from solutions are identified, along with an evaluation of the costs associated with sorbents. Special attention is given to the Kazmekhanobr developed technology for the intensive regeneration of ion-exchange resins saturated with gold. Additionally, capital and operational costs associated with the heap leaching process are examined, alongside environmental considerations. [ABSTRACT FROM AUTHOR]

Copyright of Nonferrous Metals (Mineral Processing Section) is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The permeability of ore is a key factor affecting the leaching effect of uranium ore, and the addition of surfactants can significantly improve the permeability of ore, thereby strengthening uranium ore leaching. This article simulates two infiltration leaching processes, atmospheric heap leaching and pressurized in-situ leaching, and explores the effect of surfactant cetyltrimethylammonium bromide on uranium leaching rate and ore permeability coefficient in both processes. The results showed that in the atmospheric heap leaching test, adding surfactants increased the ore leaching rate by 30.31% during the same 13 day test cycle, and the leaching process was mainly controlled by surface chemical reactions. In the pressurized in-situ leaching test, based on the results of a leaching cycle of 13 days, the average permeability coefficient increased by 72.89% and 64.07% after adding surfactants to the drained and water containing uranium deposits, respectively. In addition, the peak uranium concentration in the leaching solution appeared 2 days earlier, indicating that the addition of surfactants has a significant promoting effect on in-situ leaching of uranium, improving the leaching efficiency of uranium, and can improve the leaching rate of uranium within the same leaching cycle. [ABSTRACT FROM AUTHOR]

This paper studies the influence of the staged particle sieving-out method on the seepage characteristics in loose sandstone heap leaching. The staged sieving out of ore sample particles was conducted according to particle size, and ground pressure was applied to them. Subsequently, parameters such as the permeability, particle distribution, and pore distribution characteristics of the rock samples were obtained to investigate the influence of the staged particle sieving-out method on the seepage effect of loose sandstone heap leaching. The results indicate that sieving out particles smaller than 0.15 mm can significantly reduce the probability of hole blockage and increase the overall pore size, greatly enhancing permeability. Sieving out particles with sizes between 0.15 mm and 1.2 mm can result in the loss of skeleton particles, reducing the amount of flow channels and thereby decreasing permeability. Sieving out particles larger than 1.2 mm can reduce the overall particle size of rock samples, improve strength and pressure stability, and help maintain permeability. In the surface heap leaching of loose sandstone ore, by sieving out particles smaller than 0.15 mm during deep heap construction and sieving out particles larger than 1.2 mm during mid-level heap construction, and by using vat leaching for sieved-out particles, the seepage effect of the ore heap can be significantly optimized, and complete utilization of resources can be ensured. [ABSTRACT FROM AUTHOR]

We study the material composition of a ferromagnesian oxidized nickel ore of the Serov deposit. According to the results of chemical analysis, it was found that the studied ore is poor in the nickel content. Note that magnesium and iron are present in the ore as macroimpurities. The main nickel-containing minerals are lizardite and clinochlore; smaller amounts of nickel are contained in talc. To determine the optimal technological parameters of heap leaching and reveal their correlation dependences, we use the mathematical method of data processing, namely, the Box–Wilson steep ascent method. Based on the results of leaching, we compute the values of the efficiency criterion and the variance of the efficiency criterion and deduce a regression equation for the description of the process of leaching. The adequacy of the regression equation is established by using the Fisher criterion. The results of mathematical processing of the experimental data show that the concentration of sulfuric acid in the solution, the pause between irrigations, and the specific consumption of the leaching solution exert a significant effect on the efficiency of leaching in the stage of nickel extraction from 0–30%. On the basis of computed values of the efficiency criterion, we determine the values of variable parameters for the second stage of determination of the optimal conditions of leaching guaranteeing the efficient ore opening in the stage of nickel extraction up to 30%. [ABSTRACT FROM AUTHOR]

Copyright of Mining & Metallurgical Engineering is the property of Mining & Metallurgical Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper investigates durability related properties of concretes containing copper heap leach residue (CHLR) as partial replacement of natural fine and coarse aggregates. The use of CHLR as aggregates in concretes promotes the reduction of the dependance on natural aggregates, upcycling of the waste as aggregates and the reduction of carbon footprint associated with natural aggregate productions. In this study, CHLR was washed, dried, and sieved to separate fine aggregate and coarse aggregate, and concretes were prepared with a cement content of 400 kg/m3 and water-cement ratio of 0.435 by replacing 25-75% natural fine and coarse aggregates. The concrete containing 50% CHLR as a partial replacement of natural CA and FA gained compressive strength of 52.9 and 54.0 MPa; drying shrinkage of 662 and 538 με; volume of permeable voids of 6.2 and 5.7%; 1485 and 2640 coulomb of charge passed in chloride permeability; and primary sorptivity coefficients of 4.0 × 10−3 and 4.3 × 10−3 mm/sec0.5 at 180 days, respectively. In contrast, these properties for the control specimens at the same age were 59.1 MPa, 394 με, 5.19%, 1280 coulomb, and 2.5 × 10−3 mm/sec0.5, respectively. The compressive strength and durability aspects declined in concretes using 75% CHLR coarse and fine aggregates. Existing analytical models for durability related properties of concrete containing natural aggregates are compared to that of the concretes using CHLR. Finally, backscattered electron images coupled with energy dispersive x-ray spectroscopy of the CHLR concretes were analyzed to understand the pore refinement, interfacial transition zones, microcracks, and hydration products influencing the durability aspects. [ABSTRACT FROM AUTHOR]

The degradation behaviour of a 4.8 mm thick elastomeric bituminous geomembrane (BGM) immersed in pH 0.5, 9.5, and 11.5 synthetic mining solutions is examined over 26 months at 22, 40, 55 and 70°C. The low pH solution simulates the leach solutions found in copper, nickel, and uranium heap leach pads while the two high pH solutions simulate the chemistry and pH found in gold and silver heap leaching facilities. The mechanical, rheological, and chemical properties are examined at different incubation times to assess the degradation in the BGM at different temperatures. It is shown that the degradation rates of all properties are faster in pH 11.5 and 9.5 than in pH 0.5. Additionally, the BGM started to exhibit degradation in its mechanical properties even with a slightly degraded bitumen coat in all the mining solutions at elevated temperatures. The time to nominal failure of the BGM is predicted at different field temperatures using Arrhenius modelling. Due to the relatively fast degradation in the mechanical properties of the BGM, especially at temperatures above 50°C, the tensile strains in the BGM in the field should be limited so it can meet the required liner design life of heap leaching applications. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the effective use of a mixture of steel sludge (S1) and slag (S2) from the converter process of steel production for the production of cement mortars. Metallurgical waste used in the research, which is currently deposited in waste landfills and heaps near plants, posing a threat to groundwater (possibility of leaching metal ions present in the waste), was used as a substitute for natural sand in the range of 0–20% by weight of cement (each). The obtained test results and their numerical analysis made it possible to determine the conditions for replacing part of the sand in cement mortars with a mixture of sludge and slag from a basic oxygen furnace (BOF) and to determine the effects of such modification. For the numerical analysis, a full quadratic Response Surface Model (RSM) was utilized for two controlled factors. This model was subsequently optimized through backward stepwise regression, ensuring the inclusion of only statistically significant components and verifying the consistency of residual distribution with the normal distribution (tested via Ryan-Joiner's test, p > 0.1). The designated material models are helpful in designing ecological cement mortars using difficult-to-recycle waste (i.e., sludge and converter slag), which is important for a circular economy. Mortars modified with a mixture of metallurgical waste (up to 20% each) are characterized by a slightly lower consistency, compressive and flexural strength, and water absorption. However, they show a lower decrease in mechanical strength after the freezing–thawing process (frost resistance) compared to control mortars. Mortars modified with metallurgical waste do not have a negative impact on the environment in terms of leaching heavy metal ions. The use of a mixture of sludge and steel slag in the amount of 40% (slag/sludge in a 20/20 ratio) allows you to save 200 kg of sand when producing 1 m3 of cement mortar (cost reduction by approx. EUR 5.1/Mg) and will also reduce the costs of the environmental fee for depositing waste. [ABSTRACT FROM AUTHOR]

The growing demand for valuable metals in recent decades has heightened the economic significance of extracting them from dilute solutions. This research carefully assesses the extraction efficiency of the air-assisted solvent extraction (AASX) process for effectively recovering copper from industrial dilute solutions, such as the raffinate of the solvent extraction (SX) plant and heap leach solutions. The results clearly showed that increasing the frother dosage to 50 mg/L improved the Cu extraction from 83.5% to 90.2%, but increasing the frother dosage beyond 50 mg/L did not change this response significantly. Although varying the extractant concentration and silicone oil dosage in the studied range did not affect Cu extraction, it noticeably led to an increase in the barrier metals recovery. Furthermore, a nine-step AASX system was applied to comprehensively evaluate the extraction efficiency of Cu from dilute heap leach solution. Moreover, an impressive 95.1% of Cu recovery (from a solution containing 890 mg/L Cu, 12.32 g/L Fe, 2.64 g/L Zn, and 4.1 g/L Mn) was achieved with selectivity ratios of 149.6, 153.0, and 93.5, for Cu/Fe, Cu/Zn, Cu/Mn, respectively. It could be concluded that the AASX process is an efficient and promising method for extracting Cu from industrial dilute solutions derived from secondary resources, low-grade ores, and acid mine drainages. [ABSTRACT FROM AUTHOR]

Heap bioleaching is considered to be a less energy-intensive metal-extraction technique compared to other methods, making it particularly attractive for low-grade sulfide ores. It has been successfully applied to recovery of copper, gold, and uranium from ores over decades. Despite its seemingly straightforward nature, heap bioleaching can experience failures if the ore is unsuitable or the heap leach process is not thoroughly investigated and well-developed. Therefore, multidisciplinary approaches are essential for research and development in heap bioleaching, as its performance depends on numerous processes operating across a wide range of length scales. This review focused on the current state of knowledge regarding the understanding of multi-scale mechanisms in heap bioleaching and the use of multidisciplinary approaches at different scales to develop the process. The investigation covered various scales, such as atomic and molecular, mineralogy and microbes, reaction particles, heap bioleaching units and full-scale factory production. Different approaches were employed to gain a comprehensive understanding of the microbial molecular structure and metabolism, the structure and reaction of minerals, microbial–mineral interaction, particles and aggregation states, and multiphase flow transfer, as well as laboratory experiments, modeling, industrialization, and operation optimization. We emphasized the need for collaboration among researchers from different disciplines and stress the importance of considering the coupling effects of physical, chemical, and microbiological factors when running heap bioleaching plants. Such collaboration and coupling are vital for successful implementation and optimization of heap bioleaching processes. This paper aimed to provide a comprehensive overview of current research related to heap bioleaching at different scales and disciplines, and gave implications to heap bioleaching technology development. [ABSTRACT FROM AUTHOR]

In order to reduce odor emissions and surface water pollution while storing manure in field heaps near a barn, there is a challenge in properly designing manure-storage areas. Therefore, it is important to assess what solutions and conditions, considering environmental requirements, should be considered when storing manure in field heaps. The goal of the research is to determine the impact of various factors on the risk of nutrient leaching, soil, and gas emissions from solid manure heaps, considering climatic factors in the environment. Through various scientific studies, a manure pile model has been developed and evaluated for its impact on the risk of potential leaching and odor emissions (using hyperspectral gas emission analysis mass flow method) from manure and the dynamics of the 0–80 cm soil layer properties (nitrate (N-NO3) and nitrite (N-NO2), ammonia (NH3), mineral, and total N). Based on the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania. An optimal new manure heap model has been identified—a layer of not less than 20 cm of compacted straw (density 150–200 kg m−3) or a 10 cm layer of peat for absorbing manure slurries is formed on the soil surface, the manure heap is surrounded by an earth embankment not less than 30 cm high, the manure heap is covered with a layer of finely chopped straw not less than 10 cm thick, or 5 cm of sawdust, or 5 cm of peat. The manure is stored in the heap for 6–12 months. Following the research results, requirements for manure management and storage during the prohibited fertilization period were established, considering the requirements for nitrates from agricultural sources in Lithuania, applicable to the northern part of the temperate climate zone and applying similar requirements to the relevant countries. [ABSTRACT FROM AUTHOR]

In the heap leaching process, the free particles in the heap leaching system move with the flow of the solution, which affects the speed and efficiency of the leaching. For small grain-size particles, although it is difficult to clog the interparticle pores, a large amount of them attached to the pore wall also affects the infiltration of solution into the ores, which decreases the leaching efficiency. In this work, based on the real pore structure, Fluent software was applied to perform simulations, and the influences of particle size, particle density, and fluid flow velocity on the migration and adhesion behavior of fine particles in the pore were examined. The simulation results reveal that when the particle size is 1×10−6 m, almost no particles are deposited in the pores. With increasing particle size from 1×10−6 to 1×10−4 m, the number of particles attached to the surface of the pore wall first increases and then decreases. For particles with different densities, the number of attached particles accounts for more than 90% at the peak. The main adhesion sites of particles are the outer walls of curved pores and the small pores with low flow velocity and low slope. The analysis shows that the larger the particle size and density, the greater the influence of gravity and inertia on its trajectory, the smaller the influence of fluid on its trajectory, and the easier it is to become close to the pore wall during migration, leading to particle attachment. Moreover, the large particle size and large density particles primarily migrate in the large pores, and the trajectories are relatively concentrated. However, when small particle size and small density particles migrate in high flow velocity fluid, their horizontal motion amplitude is larger, the migration trajectory distribution is more dispersed, and the distribution is also in small pores. The adhesion of fine particles is not conducive to mineral leaching in the actual heap leaching process. In this study, the migration and adhesion laws of fine particles in pores were examined by simulations. The results reveal that it is necessary to take measures to decrease the content of fine particles when the content of fine particles is too high in the actual production process to avoid the adverse effects of particle adhesion on leaching.

A method to assess the influence of tension cracks on the seismic external stability analysis of geosynthetic-reinforced soil slopes is carried out in the present study. In addition to being subjected to uniform surcharge loading, hydrostatic and hydrodynamic pressures with water on both sides of the c-ϕ soil slope and seismic inertia forces are considered, and the reinforcement length for both sliding and overturning conditions is evaluated by using a two-part wedge mechanism. The analysis is implemented separately by considering and neglecting the effect of the formation of tension cracks, and reinforcement lengths are evaluated for both the slope angles 60° and 70°. It is seen that when the horizontal seismic acceleration coefficient increases from 0 to 0.2 for a 60° slope angle under the direct sliding mode of failure for a particular set of input parameters as shown in Table 3, the required minimum length of the geosynthetic reinforcement increases from 0.59H to 1.30H, and in the overturning mode, it increases from 0.46H to 0.60H, when the analysis is implemented without considering similar tension cracks when tension cracks are considered in the study, for the increases in kh, as mentioned previously, required minimum length of the geosynthetic reinforcement against direct sliding mode of failure increases from 0.80H to 1.67H, and increases from 0.55H to 0.64H for overturning mode of failure. In addition to kh, the influence of the height of water on the downstream side, pore pressure ratio, soil friction angle, cohesion, and surcharge on the length of reinforcement against sliding and overturning modes of failure are presented in this paper in the form of design charts. The results obtained from the present study are compared with the previous literatures and usefulness of the present method in analysis of reinforced soil slopes against direct sliding and overturning modes of failure has been proposed. The present research work delves into the external stability analysis of reinforced soil slopes. This analysis evaluates the optimal length of reinforcement necessary to maintain long-term safety and stability against potential failures, such as direct sliding and overturning. While direct sliding is influenced by forces pushing the slope forward, overturning is concerned with rotational risks. Geosynthetic reinforcement for soil slope stability plays a crucial role in stabilizing slopes across various infrastructures: highways, railways, airports, landfills, mining operations such as tailings dams and heap leach pads, urban developments, and erosion control measures along riverbanks and shorelines. Adopting the insights and methodologies of this research can amplify the safety benefits by reducing landslide risks and facilitating the customization of designs according to specific site conditions. This approach paves the way for a more efficient use of resources, ultimately slashing costs and bolstering the long-term reliability of slope performance. Furthermore, the study presents a clear analysis of geosynthetic-reinforced soil slopes, considering soil properties, failure risks, seismic forces, and water effects. This framework, suitable for both experts and novices, bridges academic research with practical engineering, making the latest insights usable and valuable for the engineering community. [ABSTRACT FROM AUTHOR]

To unveil the impact of each condition variable on the leaching efficiency index during the heap leaching process of rare earth ore and establish a prediction model for leaching conditions and efficiency, common parameters in the heap leaching process of rare earth ore were selected. In addition, the pilot-scale test data were collected over 50 days. Based on the collected data, the Ordinary Least Squares (OLS) linear regression method was used for fitting analysis to determine each variable's influence on the change in leaching efficiency. The results indicated a linear relationship between the flow rate of the leaching solution and leaching efficiency. In contrast, no obvious linear relationship was observed between other condition variables and leaching efficiency. Spearman's rank correlation coefficient was calculated to analyze the nonlinear correlation between the abovementioned variables and the leaching efficiency index. The correlation coefficients were found to be −0.78, 0.88, −0.93, −0.53, 0.71, and −0.93 for ammonium content in the leaching agent, pH of the leaching agent, rare earth content, ammonium content in the leaching solution, pH of the leaching solution, and the flow rate of the leaching solution, respectively. This suggests that the flow rate of the leaching solution, rare earth content, and pH of the leaching agent significantly influence leaching efficiency, thus affecting the rare earth leaching efficiency index. Based on the correlation analysis results of leaching conditions and efficiency, a dataset with limited data trained by the common Ordinary Least Squares model, linear regression model, random forest model, and support vector machine regression model was selected to develop a prediction model for the leaching process data. The results indicated that the random forest model had the lowest mean square error of 7.47 among the four models and the coefficient of determination closest to 1 (0.99). This model can effectively analyze and predict condition variables' data and leaching efficiency index in the heap leaching process of rare earth ore, with a prediction accuracy exceeding 90%, thus providing intelligent guidance for the heap leaching process of rare earth ores. [ABSTRACT FROM AUTHOR]

A custom-designed apparatus (referred to as the Ageing Column) is used to age a 4.8-mm thick elastomeric bituminous geomembrane (BGM) under single-sided exposure to a synthetic municipal solid waste (MSW) leachate and a synthetic high pH mining solution (pH 11.5) at 55 °C, 70 °C, and 85 °C. This apparatus involves a closer simulation of the BGM's chemical exposure conditions in the field than the double-sided immersion tests in which the BGM is exposed to the solution from both surfaces. The mechanical, rheological, and chemical properties of the BGM are examined to assess the degradation in the BGM components relative to double-sided immersion experiments. While the single-sided ageing of the BGM reduces the degradation rates in the BGM mechanical properties, it does not affect the degradation rate of the bitumen coat relative to the double-sided exposure. Additionally, the exposure of the BGM to the MSW leachate resulted in faster degradation in its mechanical properties but slower degradation in the bitumen coat than that obtained in the exposure to the mining solution. However, predictions of the time to nominal failure of the BGM established using Arrhenius modelling at different temperatures show that the temperature effect is more significant on the BGM durability than the chemistry of the considered solutions. [ABSTRACT FROM AUTHOR]

Equipment of open pit placer mining is examined. The process designs of incremental end-to-end gold recovery from placer sands are substantiated. In structurally complex extraction blocks, stripping is carried out first, and then, the limits of rich sand pockets are adjusted during the second-phase denser-grid exploration. Different-grade sands are extracted selectively. Extraction and transport of standard-grade and low-grade sands, which are the bulk of an operating block, is implemented by heavy-duty bulldozes; the standard-grade sands are sent to sluicing, and the low-grade sands are used to make heap leaching piles. High-grade sands, which make a small volume of an operating block, are transported to a multi-stage processing facility for the high-efficiency gold recovery. Tailings of standard-grade and high-grade sand processing, with mainly fine and very fine gold content, go to heap leaching. [ABSTRACT FROM AUTHOR]

In response to the slow gold leaching rate and low gold leaching rate during the heap leaching process of a fine-grained dissemination, slimy, oxidized gold ore in Guizhou, the on-site production process was optimized. Based on ore process mineralogy research and heap condition experiments, combined with the actual production on-site, the main reasons hindering the gold recovery during the heap leaching process were diagnosed. These included the presence of gold minerals in fine particle form, low dissociation degree of mineral monomers, high content of easily sliming minerals, poor permeability of ore heaps, low pH value and cyanide mass fraction in leaching solution, and high spray intensity. Corresponding optimization measures were formulated to address the problems in the production process. After on-site renovations, the gold leaching rate increased from 35% to 57%, achieving the expected optimization effect and providing significant economic benefits for the company. [ABSTRACT FROM AUTHOR]

In the recycling of low-value metallic elements, heap leaching is commonly employed. The particle size distribution is a crucial parameter in heap leaching implementation, and the percolation behavior of a heap has always been a focal point in heap leaching technology. This paper utilizes a novel form of ultraviolet fluorescence image acquisition and fluorescence image analysis to investigate the percolation process with different fractal dimension particle size distributions, where the maximum particle diameter is 10 mm. The ore used was low-grade copper ore. The results indicate that the new fluorescence image analysis method can reveal different percolation regions during the heap leaching process, aiding in a better understanding of heap leaching behavior. The combined study found that under irrigation conditions of 10 mL/min, seepage was more uniform under the heap structure formed by a particle gradation with a fractal dimension of 2.2. [ABSTRACT FROM AUTHOR]

Purpose. Determination of the thermal effect (combustion) on the geochemical characteristics of waste rock argillite, and on the leachability of pollutants for establishing the potential of these compounds as a source of drainage and groundwater pollution. Methodology. The article describes the investigation of argillite, the main component of the basin’s waste heaps, the analysis of pollutant leaching from unburned and burned argillite using a washing plant, their X-ray fluorescence analysis, the surface morphology of different types of argillite by scanning electron microscopy (SEM), the qualitative and quantitative composition of samples using energy dispersive X-ray spectroscopy (EDS) and the content of water-soluble heavy metals by atomic absorption. Findings. As a result of thermal effects on argillite, the salt content in the washing water increases by 2.5 times and reaches 185 ppm in water from unburned rock and 462 ppm from burned rock, the sulfur content in the burned rock after washing decreased by 21.3 times. The variability of changes in the content of water-soluble compounds in the studied samples is also noted, since the amount of Mn, Pb, Cu and Co leached out is up to 15.5 times higher in unburned argillite, but the amount of Fe and Zn leached out after combustion increases up to 17.4 times compared to unburned rock. Originality. The series of changes in the content of chemical elements and compounds as a result of combustion and rock washing have been established, which are important for assessing and predicting the migration potential of chemical elements from coal dump rocks to soils and waters within coal spoil tips. Practical value. The conducted research characterises the ecological state of spoil tips and can be used for reclamation or melioration works in these areas, taking into account the degree of rock metamorphism. [ABSTRACT FROM AUTHOR]

Biomass, primarily derived from photosynthesizing plants harnessing solar energy, is crucial for ecosystem functioning and diverse services. This study delved into the unique ecosystem of coal mine heaps, exploring unexpected relations between abiotic factors and biomass in spontaneous vegetation. Biomass quantity and quality are influenced by such factors as plant photosynthesis efficiency, necessitating an understanding of dynamics on postmining sites. The conducted investigation focused on diverse spontaneous vegetation on coal mine heaps, analyzing abiotic conditions such as soil texture, water holding capacity, pH, electrical conductivity, nitrogen, carbon, magnesium, sodium, and acidity. Contrary to the adopted hypothesis, nitrogen content negatively correlates with soil total nitrogen, carbon, and water holding capacity. However, the biomass of dominant plant species positively correlates with available phosphorus, pH, calcium, and sodium. These unexpected relationships highlight biomass dynamics complexity in novel ecosystems on coal mine heaps, stressing the need to consider spontaneous vegetation biomass as a valuable resource and ecosystem service in urban-industry landscapes. The obtained findings expand scientific inquiry and have practical implications for post-industrial area reclamation. Understanding biomass potential in identified vegetation types provides insights into biomass character on coal mine heaps, crucial for maximizing spontaneous vegetation potential and transforming post-industrial landscape reclamation approaches. [ABSTRACT FROM AUTHOR]

The ore agglomerations could ameliorate intra-particle pore network, homogenize flow paths, and improve leaching efficiency of heap leaching. This paper innovatively develops a novel ore granulator with adjustable inclined angle and rolling speed. To comprehensively evaluate granulation procedure, the effects of physical (crushed feeds particle size distribution, rolling speed, inclined angle), chemical (binder type, curing time) and biological factors (bacterial concentration) on bonding performance of crushed feeds are analyzed. The objective of this paper is to obtain the optimal granulation conditions by studying the influence of various factors on the bonding ability, strength, and stability of granulated ores, in order to improve the pore structure of the heap leaching system, and increase the leaching rate of the ore. The results show that well-shaped agglomeration (WAs) does improve minerals leaching efficiency, and the uniaxial compressive strength of WAs is positively related to curing time, binder concentration, inclined angle, and rolling speed. The excessive lower or higher rolling speed is not suitable to get a higher extraction rate due to undesirable disintegration or compaction. The higher concentration (0.5–10 %) sulfuric acid solution could obviously increase WAs strength from 32.6 KPa to 48.3 KPa. The organic binders such as polyacrylamide are benefit for powders bonding and increase the compressive strength, but does not good for the desirable leaching reaction rate. The bacterial pre-adding has no significant positive influence on bonding and leaching efficiency. Relied on the 3D response surface, the preferred preparing condition is: 78.9 rpm rolling speed, 30° inclined angle, 7-days curing time and 9.3 % H2SO4 solution. Future studies should focus on exploring the intrinsic correlation between the various factors and evaluating the granulating and leaching effects from the perspective of chemical detection and leaching bacteria.

Rare earth elements (REE) are essential components in various modern technologies. Mining activities, in contrast, severely destabilize the adjacent ecological systems. The soil transformation environmental issue in mining areas is inextricably linked to process techniques. Inconsistencies in harm and serviceability arise from different mining techniques. This study was conducted in Fujian, China, which has abundance of ion adsorption type rare earth resources (IAT-Res). We investigated the soil interaction effects of two mining techniques (heap leaching and in-situ leaching). After eight years of restoration, soil destruction and nutrient imbalance remain significant in the heap leaching mining regions. The effects of heap leaching are distinct, whereas pollution caused by in-situ leaching is hidden. Although the in-situ leaching technique resulted in less soil erosion, its potential environmental risk cannot be ignored. The greater number of (NH4)2SO4 leachate residues left over after in-situ leaching contaminate the surrounding ecosystem as they are easily translocated. Through this study, we demonstrate the ecological impacts of different mining techniques in mining areas. As a result, to obtain accurate protection and contaminant control management. However, additional interests should address the leachate and REE pollution caused by in-situ leaching in a larger region. [ABSTRACT FROM AUTHOR]

The mining sector actively seeks to improve operational processes and manage residual materials, especially in areas used for heap leaching disposal. The flowability of residues following deposition can have an impact on storage capacity, productivity, and workers' safety. In this study, an artificial neural network (ANN) approach is applied to evaluate the accuracy of three models in predicting the flowability of spent heap leach when it is discharged into the dump, considering three or five segregation categories. The models with five categories exhibited the highest level of accuracy, with learning responses ranging from 72% to 78% and predictions from 88% to 96%. These indicate that ANN models have the potential to be a decision-making tool for the discharge strategy in the dump. Modules containing lithologies such as clays and phyllosilicates exhibited increased susceptibility to separation due to their water retention capacity, which negatively impacted their permeability and conductivity. The decomposition of iron oxide, along with clays and low hardness, led to the formation of fines, limited permeability, and inadequate solution drainage. Rock competence and low formation of fines provide good permeability, and better drainage conditions for the solution, and help maintain the stability of the spent heap leach in the dump. [ABSTRACT FROM AUTHOR]

In hydrometallurgical processing of oxidized gold-bearing ores, copper, cobalt, zinc, and other metals, along with gold, dissolve in sodium cyanide alkaline solutions forming metal cyanide complexes, which have a negative impact on the gold leaching process. One method for removing copper from cyanide solutions is sorption using anion exchange resins. This article discusses the choice of a sorbent for sorption of gold, copper and cobalt from production and barren gold-containing solutions. Sorption studies are conducted on production solutions obtained during heap leaching of gold from ore (gold 1.13-1.20 mg/liter; copper 60.8-63.2 mg/liter; cobalt 1.73-1.78 mg/liter; iron 0.1 mg/liter), and on barren solutions after gold extraction from production solutions using activated carbon (gold 0.19-0.26 mg/liter; copper 49.6-59.5 mg/liter; cobalt 1.61-1.83 mg/liter; iron < 0.1 mg/liter). Sorption studies are conducted using resins such as AM-2B, Purolite A-500 and AV-17-8. Research results show that sorption characteristics of the resins tested for sorption of metals (copper, cobalt) from production and barren solutions are similar. For sorption of copper and cobalt strongly basic resins AV-17-8 and Purolite A-500 demonstrate the best sorption characteristics. The mixed-base anion exchange resin AM-2B exhibits enhanced selectivity for gold. [ABSTRACT FROM AUTHOR]

The study on the bioleaching of metals from minerals is a necessity to improve the process of recovering precious metals and obtaining greater benefits. The objective was to determine in four successive reactivations, the specific growth rate and stability of microbial consortia obtained from the leaching plant of the mining company Southern Cooper Corporation (SCC) in Toquepala, Tacna - Peru. The consortia M-1, M-2, M-5, M-6, and BF-7 were obtained from chalcopyrite from the leach heaps; and the PLS-3, PLS-4, and ILS-8 of the leached liquid solutions. The liquid culture medium used was modified to 9K. The consortia had four successive reactivations in 9K medium, in triplicate, at room temperature for 15 days and with 1vvm aeration. The microbial counts obtained every eight hours in the Petroff-Hausser counting chamber were converted to the decimal logarithmic scale to obtain the growth kinetics using the Malthusian model that determined the rate constant K in the logarithmic phase and the Gompertz model to the microbial growth curve. The consortia from solid samples and biofilm had a faster adaptation, compared to those from the liquid samples of PLS and ILS, which showed an inactive microbial concentration at the beginning. All consortia after the first reactivation showed higher growth rates, the highest being in the PLS-4 consortium during the third reactivation, with a K of 0.025 h-1. The most stable growth rates occurred in the fourth reactivation in the M-6 and BF-7 consortia, these were the most indicated to continue with application studies as inoculum after a third reactivation and achieve the optimization of the bioleaching process of the mineral chalcopyrite. [ABSTRACT FROM AUTHOR]

This paper presents a generic component for Analytic Hierarchy Process (AHP)-based decision support in risk management. The component was originally dedicated to railway transportation issues; however, its generality enabled it to extend its functionality for other domains too. To show the generality of the module and possibility of its application in other domains, an environmental case was run. Its goal was to select methods for planning the post-mining heap revitalization process, especially decision-making focusing on the selection of the most advantageous revitalization option on the basis of the Analytic Hierarchy Process and different, non-financial factors, e.g., social, environmental, technological, political, etc. Taking into account expert responses, the suggested solution was related to energy production. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Heap leaching for rare earth elements poses a serious long-term threat to the adjacent ecological systems in mining areas. The purpose of this research is to thoroughly study the environmental effects of heap leaching in ion-adsorption rare earth element mine tailings after restoration by ecological measures. Soil samples were collected from four heap leaching rare earth element mine tailings and a control site to investigate their effects on topsoil chemical properties and the results of vegetation restoration. The findings revealed that the effects of heap leaching operations increase soil acidity; the soil's sand content was more than twice that of the control site, while the silt content was much lower. Natural and artificial restoration are difficult to establish in mining areas. Plant growth was hampered in the early stages of rehabilitation due to a lack of organic carbon. Then, because of the lack of nitrogen, the plants' succession did not take place over time. Therefore, carbon fertilizers are recommended at the early stage of rehabilitation and soil tumbling to increase the efficiency of nitrogen up-taking. Although heap leaching is no longer permitted, the historic environmental problem at ion-adsorption mine tailings persists. As a result, more research is needed to develop strategies for contamination management in these areas. [ABSTRACT FROM AUTHOR]

The amounts of biomass in ecosystems depends on the efficiency of energy gathering in organic chemical bonds by autotrophs, which are the only organisms that synthesize inorganic compounds into organic compounds structured into biomass. Plant species composition in the vegetation patch and the associated microorganism communities are factors that affect the matter and energy flow in the ecosystem. In human-established or severely transformed novel ecosystems, in particular in mineral-poor, oligotrophic habitats, the knowledge about the biotic parameters related to the biomass amount is very limited. The presented studies were performed on post-black coal mining heaps that provide the mineral material habitat. The following biotic parameters, the vegetation plant species composition of the distinguished vegetation types, soil organic matter, soil enzymatic activity, soil fauna presence, and the functional aspect of soil carbon release concerning amount of biomass are considered. The aim of this research was to analyze the influence of the selected biotic factors on the biomass amount in the vegetation patches of the studied sites. The results showed that the effect of the species composition diversity on the biomass amount is complex. The influences of soil enzyme activity on biomass amount are dependent on the enzyme presence and the vegetation type. Similarly, the impact of the soil organic matter (SOM) on the biomass amount is significantly different and dependent on vegetation type. The relationship between the amount of biomass and respiration showed that the biomass of the dominant plant species is positively correlated with the biomass amount in the studied vegetation types. [ABSTRACT FROM AUTHOR]

In the past two decades, the mining sector has increasingly embraced simulation and modelling techniques for decision-making processes. This adoption has facilitated enhanced process control and optimisation, enabling access to valuable data such as precise granulometry measurements, improved recovery rates, and the ability to forecast outcomes. Soft computing techniques, such as artificial neural networks and fuzzy algorithms, have emerged as viable alternatives to traditional statistical approaches, where the complex and non-linear nature of the mineral processing stages requires careful selection. This research examines the up-to-date use of soft computing techniques within the mining sector, with a specific emphasis on comminution, flotation, and pyrometallurgical and hydrometallurgical processes, and the selection of soft computing techniques and strategies for identifying key variables. From this, a soft computing approach is presented to enhance the monitoring and prediction accuracy for mineral waste disposal, specifically focusing on tailings and spent heap leaching spoils database treatment. However, the accessibility and quality of data are crucial for the long-term application of soft computing technology in the mining industry. Further research is needed to explore the full potential of soft computing techniques and to address specific challenges in mining and mineral processing. [ABSTRACT FROM AUTHOR]

Accurate measurement of solution tracer concentration in residence time distribution (RTD) tests can be difficult in low volumetric flowrate systems where solution must be accumulated over a period before there is sufficient volume for a tracer concentration measurement. This is encountered with laboratory-scale heap leaching column salt tracer RTD tests. Step-up tracer experiments were used to show how this results in tracer concentration underestimation (due to mixing effects) and loss of profile features, such as tracer concentration step changes. A tracer measurement setup was conceived to overcome this. It was designed to have well-defined flow which could be described using a compartment model of a plug flow and well-mixed volume in series. The model was used to calculate "true" tracer concentrations from the measured values (correlation coefficients greater than 0.983). It was demonstrated to be effective at both correcting tracer concentration magnitudes and restoring lost profile features. [ABSTRACT FROM AUTHOR]

Permeability reduction is a major challenge in heap leaching, primarily caused by the accumulation of fines that move with the leaching agent, leading to the formation of dead zones and channeling within the heap. In the Aria copper beneficiation plant, the 0-2 mm fraction with a copper grade of 1.4% undergoes pre-separation prior to heap loading without further processing. This study investigated the potential of using the agglomeration method to improve permeability in the case of using the 0-2 mm fraction of ore. Mineral compounds, such as sodium silicate and calcium sulfate, and non-ionic, cationic, and anionic polymer compounds, were used in the agglomeration process. The strength of interparticle bonding was evaluated by measuring the fine migration percentage (FMP) in the soak test. The results revealed that agglomerates produced using non-ionic compounds had the highest bonding strength, with an FMP of 3.89%, the lowest of all the compounds tested. This enhanced bonding strength was attributed to the combined influence of hydrogen bonding forces and van der Waals forces. [ABSTRACT FROM AUTHOR]

In the case study of the pollution control over the heap leaching cyanide residue left by historical gold mines in arid areas of western China. Based on a thorough analysis of climate, hydrogeology, and the characteristics of heap leaching cyanide residue pollutants, in-situ closure operation is employed to verify the pollution control effect over the pollutant such as heavy metals in heap leaching cyanide residue. The paper in detail describes the in-situ sealing and isolation scheme, control and monitoring scheme, and auxiliary schemes. After implementation, the environmental pollution risks are effectively controlled, and the peripheral environment is evidently improved, achieving anticipated engineering goals. The control technology can provide references for the pollution control of heap leaching cyanide residue generated from similar gold mines. [ABSTRACT FROM AUTHOR]

The durability of five 1.5-mm thick geomembranes (GMBs) is investigated in pH 0.5 and 13.5 synthetic mining solutions using immersion tests. Two high density polyethylene (HDPE), two linear low density polyethylene (LLDPE), and one blended polyethylene (BPO) GMBs are investigated at 85 °C for incubation durations of 4.5–6.5 years. It is shown that the degradation of all five GMBs in the high pH solution is faster than in the low pH solution. In the pH 0.5 solution, one of the HDPEs and the BPO GMBs exhibited polymer degradation before or at the time of the depletion of their antioxidants. In pH 13.5, four out of the five GMBs exhibited degradation and followed the conceptual three-stage degradation model until nominal failure. However, there is no correlation between the long-term performance of these GMBs and their resin type or their initial properties since one of the examined LLDPEs outperformed all the higher density/crystallinity GMBs with higher initial properties while the other LLDPE did not perform well. Thus, when selecting a GMB for a desired application, the relative performance of different candidate GMBs can be only assessed using immersion tests using the solutions expected in the field. • First comparison of the degradation behaviour of HDPE, LLDPE, and BPO geomembranes incubated for up to 6.5 years at 85 °C. • Estimates the time to nominal failure in pH 0.5 and pH 13.5 synthetic mining solutions. • Examines the role of the stabilizers and the resin type on the longevity of five different geomembranes. • Compares the morphology of the failure surfaces after stress cracking from HDPE, LLDPE, and BPO geomembranes. [ABSTRACT FROM AUTHOR]