Mine Waste Research Articles

The Potential Use of Pseudomonas stutzeri as a Biocatalyst for the Removal of Heavy Metals and the Generation of Bioelectricity

Currently, industry in all its forms is vital for the human population because it provides the services and goods necessary to live. However, this process also pollutes soils and rivers. This research provides an environmentally friendly solution for the generation of electrical energy and the bioremediation of heavy metals such as arsenic, iron, and copper present in river waters used to irrigate farmers’ crops. This research used single-chamber microbial fuel cells with activated carbon and zinc electrodes as anodes and cathodes, respectively, and farmers’ irrigation water contaminated with mining waste as substrate. Pseudomonas stutzeri was used as a biocatalyst due to its ability to proliferate at temperatures between 4 and 44 °C—at which the waters that feed irrigated rivers pass on their way to the sea—managing to generate peaks of electric current and voltage of 4.35 mA and 0.91 V on the sixth day, which operated with an electrical conductivity of 222 mS/cm and a pH of 6.74. Likewise, the parameters of nitrogen, total organic carbon, carbon lost on the ignition, dissolved organic carbon, and chemical oxygen demand were reduced by 51.19%, 79.92%, 64.95%, 79.89%, 79.93%, and 86.46%. At the same time, iron, copper, and arsenic values decreased by 84.625, 14.533, and 90.831%, respectively. The internal resistance values shown were 26.355 ± 4.528 Ω with a power density of 422.054 mW/cm2 with a current density of 5.766 A/cm2. This research gives society, governments, and private companies an economical and easily scalable prototype capable of simultaneously generating electrical energy and removing heavy metals.

Electrochemical deposition of hydrothermally pretreated TiO2 on aluminium substrate through the formation of peroxotitanium complex and their application towards visible light assisted photocurrent generation

Herein, we report a novel method for the electrochemical deposition of TiO2 on Al substrate through the formation of peroxotitanium complex without any post heat treatment process. The alkaline treated titanium precursors were used as an electrolyte and TiO2 was deposited onto aluminium substrate by both cathodic reduction and electrophoretic deposition through the formation of peroxotitanium complex. The electrodeposition process was optimized by varying the pH, concentration of the electrolyte, deposition voltage, time and area of the electrode respectively. The optimized condition to obtain a maximum yield is as follows: voltage (4.5 V), time (2.5 h), pH (5) and area of the electrode 3 × 3 cm2. The deposits were then characterized using various material characterization techniques such as high-resolution transmission electron microscopy (HR-TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and Raman spectroscopy respectively. The morphological analysis showed the deposition of nanocrystalline TiO2 with irregular morphology on Al substrate. The AFM revealed a non-uniform deposition of TiO2 with high surface roughness (average roughness: 44.60 nm). The XRD pattern and Raman spectrum confirmed the presence of anatase phase of TiO2. The obtained TiO2 were then subjected to photoelectrochemical studies by coating over an ITO electrode. The nanocrystalline TiO2 showed excellent photocurrent response which could be due to the short hole retrieval and fast electron transport across the electrode-electrolyte interface. The proposed method can be promising towards the industrial application for the extraction and recovery of TiO2 from the mineral ore residues and spent mining waste.

Combining approaches for environmental assessment of rehabilitated gold‐mining areas in the Eastern Amazon

AbstractMonitoring key soil and vegetation attributes in mining areas under environmental rehabilitation is essential to ensure that the intervention techniques are effective. There are several approaches to monitoring mining areas and their integration is necessary to process large amounts of information. Thus, this study aimed to (i) assess soil multi‐contamination with potentially toxic elements (PTE) and human health risks; (ii) obtain a soil quality index with soil fertility data; (iii) calculate spectral index; (iv) show rehabilitation status based on vegetation attributes, and (v) compile these indices in a single measure. Four tailings' ponds (TPs), two waste piles (WPs), and an area of native forest from a gold mine in the Carajás National Forest were evaluated. Soil quality and vegetation cover are good in forest areas, with no evidence of PTE contamination. On the other hand, the TPs have poor fertility and vegetation cover, as well as higher levels of PTE. Human health risk indices obtained for all PTE were lower than 1, indicating a low risk to human health. The results of integrating the different indices suggest that the environmental conditions of the WPs are better than those of the TPs, which are still far from the environmental conditions of native areas. Soil attributes and vegetation development in TPs areas could be enhanced by the incorporation of organic materials and fertilizers and by planting species with phytoremediation potential. Finally, the integrative approach of the different indices proved to be useful in assessing the rehabilitation progress of the areas.

Ethnobotanical, ecological and health risk assessment of some selected wild medicinal plants collected along mafic and Ultra Mafic rocks of Northwest Pakistan.

The current study investigated wild plant resources and health risk assessment along with northern Pakistan's mafic and ultramafic regions. Ethnobotanical data was collected through field visits and semi-structured questionnaire surveys conducted from local inhabitants and healers. Six potentially toxic elements (PTEs) such as lead (Pb), cadmium (Cd), nickel (Ni), chromium (Cr), manganese (Mn), and zinc (Zn) were extracted with acids and analyzed using atomic absorption spectrophotometer (AAS, Perkin Elmer-7000) in nine selected wild medicinal plants. Contamination factor (CF), pollution load index (PLI), estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) were used to determine the health risk assessment of the studied medicinal plants. The results showed that the selected medicinal plants were used for the treatments of cough, joint swelling, cardiovascular disorders, toothaches, diabetes, and skin pimples by the local inhabitants due to their low-cost and easy accessibility. The concentrations of Pb (3.4-53mgkg-1), Cd (0.03-0.39mgkg-1), Ni (17.5-82mgkg-1), Cr (29-315mgkg-1), Mn (20-142mgkg-1), and Zn (7.4-64mgkg-1) in the studied medicinal plants were found above the safe limits (except Zn) set by WHO/FAO/USEPA (1984/2010). The Pb contamination factor was significantly (p < 0.05) higher in A. modesta (7.84) and D. viscosa (6.81), and Cd contamination factor was significantly higher in C. officinalis (26.67),followed by A. modesta (8.0) mg kg-1. Based on PTE concentrations, the studied plants are considered not suitable for human consumption purposes. Pollution load index values for A. modesta, A. barbadensis, A. caudatus, A. indica, C. procera (2.93), D. viscosa (2.79), and C. officinalis (2.83), R. hastatus (3.12), and Z. armatum were observed as 1.00, 2.80, 2.29, 2.29, 2.93, 2.79, 2.83, 3.12 and 2.19, respectively. Hazard index values were in order of R. hastatus (1.32 × 10-1) ˃ C. procera (1.21 × 10-1) ˃ D. viscosa (1.10 × 10-1) ˃ A. caudatus (9.11 × 10-2) ˃ A. barbadensis (8.66 × 10-2) ˃ Z. armatum (7.99 × 10-2) ˃ A. indica (6.87 × 10-2) ˃ A. modesta (5.6 × 10-2) ˃ C. officinalis (5.42 × 10-2). The health risk index values suggested that consumption of these plants individually or in combination would cause severe health problems in the consumers. Pearson's correlation results showed a significant correlation (p ≤ 0.001) between Zn and Mn in the studied medicinal plants. The current study suggests that wild medicinal plants should be adequately addressed for PTEs and other carcinogenic pollutants before their uses in the study area. Open dumping of mining waste should be banned and eco-friendly technology like organic amendments application should be used to mitigate PTEs in the study area.

Environmental compliance assessment for the desulfurization of sulfide mine waste tailings: A case study of Ok Tedi Mine, Papua New Guinea

The effective management of sulfide mine waste tailings is a complex task because of the potential for acid rock drainage to harm aquatic ecosystems. Although previous research has explored the environmental consequences of sulfide mine waste tailings and the potential advantages of desulfurization method, there is a lack of studies examining the environmental compliance of desulfurization efforts. To bridge this knowledge gap, a study was conducted at the Ok Ted Mine to evaluate the environmental compliance of the implemented desulfurization process. Ninety samples of sulfide tailing, desulfurized tailing, and sulfide concentrate were collected and analyzed for geochemical and physical properties. The acid-generating capacities were assessed using the Sobek's static test, whereas the particle size, pH, and recovery were evaluated for the overall performance of the desulfurization process. These findings indicated that the desulfurization process significantly reduced the acid-generating capacity and heavy metal concentrations of the sulfide tailings below the regulatory threshold levels. Therefore, the desulfurization approach employed at the Ok Ted Mine comply with the environmental regulaotry requirments. For further assessment, a study is recommended to evaluate the impact of desulfurization on the ecosystem to predict full extent of biodiversity recovery after mine life.

Overview Metode Fitoremediasi Dalam Pengelolaan air Tercemar Timbal (Pb)

Wastewater originating from industry varies greatly depending on the type of industry. Industrial wastewater usually contains many toxic and dangerous chemical compounds (B3) and contains heavy metals. Heavy metals are pollutants that have dangerous effects because they cannot be broken down biologically and stable. Heavy metal elements can be distributed on the earth's surface in water, soil and air. Heavy metal waste pollution containing lead (Pb) is a problem for current environmental conditions. Heavy metals are found in almost all types of industrial waste. The increasing number of industries will cause increased pollution of water sources originating from industrial waste. . Therefore, effective and efficient methods are needed to manage lead-contaminated water. Methods that are easy to apply, low cost and environmentally friendly are highly desirable for managing lead-contaminated water so that the concept of good mining practice can be applied to sustainable development. The most efficient and effective method applied for mining waste management is the phytoremediation method. The results of the research state that several plants have a significant and efficient effect in helping the absorption of the metal lead (Pb) contained in water. Great Duckweed (Spirodela Polyrhiza) and Water Hyacinth (Eichhornia crassipes) are plants that are suitable for implementing phytoremediation methods in managing water contaminated with lead (Pb).

Artificial intelligence-based prediction model for the elemental occurrence form of tailings and mine wastes

With the advent of the second industrial revolution, mining and metallurgical processes generate large volumes of tailings and mine wastes (TMW), which worsens global environmental pollution. Studying the occurrence of metal and metalloid elements in TMW is an effective approach to evaluating pollution linked to TMW. However, traditional laboratory-based measurements are complicated and time-consuming; thus, an empirical method is urgently needed that can rapidly and accurately determine elemental occurrence forms. In this study, a model combining Bayesian optimization and random forest (RF) approaches was proposed to predict TMW occurrence forms. To build the RF model, a dataset of 2376 samples was obtained, with mineral composition, elemental properties, and total concentration composition used as inputs and the percentage of occurrence forms as the model output. The correlation coefficient (R), coefficient of determination, mean absolute error, root mean squared error, and root mean squared logarithmic error metrics were used for model evaluation. After Bayesian optimization, the optimal RF model achieved accurate predictive performance, with R values of 0.99 and 0.965 on the training and test sets, respectively. The feature significance was analyzed using feature importance and Shapley additive explanatory values, which revealed that the electronegativity and total concentration of the elements were the two features with the greatest influence on the model output. As the electronegativity of an element increases, its corresponding residual fraction content gradually decreases. This is because the solubility typically increases with the solvent's polarity and electronegativity. Overall, this study proposes an RF model based on the nature of TMW that can rapidly and accurately predict the percentage values of metal and metalloid element occurrence forms in TMW. This method can minimize testing time requirements and help to assess TMW pollution risks, as well as further promote safe TMW management and recycling.

Sustainability challenges of clean-energy critical minerals: copper and rare earths

The transition to a clean-energy economy in an effort to mitigate climate change has brought a need for intense mining exploration of a critical class of minerals, previously mined and used at a fraction of what is required today and for the upcoming decades. For some common metals, such as copper, major deficits are forecasted for 2030, and for some less common ones, such as rare earths, mined quantities have recently increased 32 times relative to those in the mid-1950s and are expected to increase sevenfold from current levels by 2040. This situation is expected to become more severe given the long time span needed for exploration of new sites, the declining ore grade of existing mines, the geographical distribution of these minerals and the environmental degradation caused by mining and mineral processing activities. It becomes, hence, critical to improve existing mining operations vastly, reduce waste volumes and fresh water use, reduce environmental impacts and recover increased quantities of minerals from mine tailings, as well as from the recycling of post-production products. This paper focuses on copper and rare earths to expound on their exploitation issues, their processes, the sustainable utilisation of mineral waste and tailings and their recovery from end-of-life consumer and industrial items.

Prediction of a High Concentration of PM2.5 near a Tailings Pond

Prediction of a High Concentration of PM2.5 near a Tailings Pond

Resíduo de mineração associado com bioinoculantes e esterco bovino na nutrição mineral e crescimento do milho

ABSTRACT Vermiculite mining residues, although of low solubility, contain nutrients such as calcium, magnesium, and potassium at concentrations that allow their agricultural use. Beneficial bacteria can increase the solubility of this waste and its efficiency. The objective of the present study was to evaluate the influence of bio-inoculation of vermiculite residue, associated with cattle manure, on the release of nutrients and initial growth of maize. A completely randomized design was performed in a greenhouse with seven treatments and four replications. The treatments were: T1 - soil without fertilization; T2 - soil fertilized with soluble sources of nutrients (conventional fertilization); T3 - application of vermiculite residue (VR); T4 - VR enriched with cattle manure (CM); T5 - VR + CM with Bacillus subtilis; T6 - VR + CM + B. amyloliquefaciens, and T7 - VR + CM +B. subtilis + B. amyloliquefaciens). Regardless of the use of cattle manure or beneficial microorganisms, vermiculite mining waste increased the availability of Ca and K in the soil, but was not able to match the soluble sources of nutrients. Mining waste associated with cattle manure and beneficial microorganisms (B. subtilis and B. amyloliquefaciens) increased microbial activity and enhanced the release of available calcium for maize. VR increased the growth and the dry mass production of maize compared to the non-fertilized soil, but was consistently inferior to conventional fertilizer.

Prediction of Acid Mine Drainage Generation from Mine Waste at an Abandoned Mining Site in a Semi-arid Environment

Prediction of Acid Mine Drainage Generation from Mine Waste at an Abandoned Mining Site in a Semi-arid Environment

Evaluation of heavy metal speciation distribution in soil and the accumulation characteristics in wild plants: A study on naturally aged abandoned farmland adjacent to tailings

Heavy metal composite pollution is widespread in the surrounding environment of tailings ponds in arid and semi-arid regions, leading to the abandonment of substantial agricultural land. This study investigates the speciation distribution and plant accumulation characteristics of heavy metals in abandoned farmland with different durations of natural aging. The aim is to comprehend the local heavy metal behavior pattern in the soil-plant system and offer insights for environmental remediation. Our findings reveal that Cd stands out as the primary heavy metal pollutant in this area. The mobility ranking of heavy metals is Cd > Pb > Zn > Cu, with Cd and Pb mobility decreasing along the basin. Notably, active Pb exhibits a higher affinity for soil binding compared to other metals. The predominant plant species in the region are primarily small shrubs, herbaceous plants, and semi-shrubs that demonstrate tolerance to drought and salt. Most plant samples showed elevated levels of Cd, Pb, and Zn, surpassing the maximum tolerance levels for dietary minerals in livestock. This elevated metal content poses potential threats to the health of local livestock and wildlife, yet it is also considered a potential for phytoremediation. Selected dominant plant species from the current study include Kalidium foliatum & gracile which shows potential as a Cd accumulator and indicator. Neotrinia splendens and Reaumuria songarica demonstrate potential as Cd excluders, with the latter exhibiting higher tolerance to Cd (62.9 mg/kg). Additionally, our observations indicate that different plant parts exhibit distinct responses to heavy metals, and Zn synergistically influences the aerial part accumulation of Cd.This study holds significant importance in understanding the complex behavior patterns of multi-metal pollutants in the natural environment. The identification of native plants with remediation potential is valuable for phytoremediation of environment pollution in mining area.

Phytotoxicological assessment of AMD affected river waters in “Sredna Gora”, Bulgaria to Lepidium sativum L.

The ongoing pollution of water bodies from decommissioned mines and mining waste facilities in Bulgaria is a serious problem, leading to a contamination of river waters with heavy metals. Although the chemical analyses of acid mine drainage (AMD) affected waters provide information about their toxicity, this information is not enough to evaluate the potential impacts on the biota. For this, different biological responses are used to assess the toxicity of the polluted waters.The goal of the research was to determine the phytotoxicity (using Lepidium sativum) of five affected river waters. The lower reaches of the rivers flow though agricultural areas and are often used for irrigation by local farmers, increasing the chance of produce contamination.The effect of the working solutions on seed germination and primary root growth of L. sativum was assessed by the following indices: Relative seed germination (RSG), relative root growth (RRG) and germination index (GI, the product of RSG and RRG).The obtained results have shown the connection between germination/root growth inhibition and concentrations of heavy metals in working solutions, but there is no connection between germination/root growth inhibition and pH levels.

Hydrogeochemical modelling of pyrite oxidation ion mobility in unsaturated mine waste rock piles

Hydrogeochemical modelling of pyrite oxidation ion mobility in unsaturated mine waste rock piles

Assessing the Feasibility of Implementing Porous Carbon Foam Electrodes Derived from Coal in Redox Flow Batteries

The feasibility of carbon foam electrodes derived from coal for the vanadium redox flow battery (VFB) is assessed as a pathway to repurpose mining waste for use in renewable energy storage technologies. Three-electrode, half-cell, and full-cell measurements provide proof-of-concept for coal foam as an electrode material for VFBs. Similarities in physical and chemical properties between the coal foam used here and other VFB electrode materials is characterised via SEM, micro-CT, XPS, MRI, and Raman spectroscopy. We show that significant improvement in electrochemical performance of the coal foam electrodes can be achieved via simple techniques to improve material wetting and remove impurities. The overall characteristics and electrochemical behaviour indicate that coal-derived foam can be feasibly utilised as an electrode material, and with further electrode activation, may provide a competitive solution to both cost-efficient VFBs and waste reduction.

К оценке опасности выщелачивания некондиционного сырья в кучах

The issues of identification of environmental hazards when implementing the concept of the involvement of poor metal-containing raw materials and tailings from ore processing through the application of a new leaching technology with a detailed version of heap leaching on the earth have been considered. The methodology of identification of the environmental consequences of the implementation of the technology of deep processing of non-conventional mineral raw materials considering the impact of mineral waste on the environment of the field development region has been formulated. An environmental component of the complex ecological and economic effect comprised of the consistently implemented stages of the existence of the enterprise has been considered. The main factors of negative environmental impact received a quantitative assessment; the territories adjacent to the enterprise have been ranked by the degree of the anthropogenic impact. The options to determine the extent of damage caused by the contamination of ecosystems with heavy metals have been proposed. Models to determine the environmental damage caused by industrial effluents as the main transporting medium and the efficiency of utilization of substandard raw materials based on the profit criterion have been formulated. The mechanism of removal of reagents and solutions to the environment by airflows has been specified. An approximate calculation of parameters of the environmental contamination for ore leaching of ore raw materials in the Sadonskoye deposit has been provided. It has been demonstrated that the chemical contamination of soils is prioritized when determining the environmental hazard and the hazard for the enterprise employees. It has been proved that the combined ecological and economic model of assessment of the efficiency of utilization of substandard raw materials joins ecological and economic aspects within a single natural and anthropogenic system, whereas the ecological and economic efficiency of production is a function of integrating methods of field development, including the application of a safety criterion for ecosystems of the environment. The study results can be used for the adjustment to the legislation on mining in the Russian Federation.

Influence of Physico-chemical Conditions on Mobility of Uranium from Wastes

Dynamic leaching tests were carried out on solid wastes generated from the uranium mining and milling industry under different physico-chemical conditions to assess the mobility of uranium from these matrices. The mobile/ soluble fraction of uranium leached out very slowly; being faster in the initial stages and then attaining a near steady state condition in most cases. Uranium leaching was observed to increase with decreasing initial pH, reducing particle size and increasing temperatures. A maximum of 2.4% uranium was leached out under highly acidic conditions in the experimental time period. Leachability index values indicated weak leaching of uranium from the wastes under all conditions. Leaching kinetics was examined with the help of a heterogeneous reaction model. Model results and apparent activation energy values indicated the leaching process to be initially reaction controlled and subsequently diffusion controlled. The apparent rate constants displayed dependence on the particle sizes of the tailings. All results obtained from this study imply that the extent of uranium leaching from these solid mining wastes is extremely low. This indicates low mobility and negligible transfer to other environmental compartments.

Mineral waste recycling, sustainable chemical engineering, and circular economy

The mineral processing industry is pivotal in natural resource extraction and historically contributes to environmental damages like land degradation and groundwater contamination. In the face of resource scarcity and environmental pollution, sustainable solutions are increasingly vital. The circular economy focuses on reusing, recycling, and reducing waste, which turns unwanted by-products into valuable assets. Sustainable chemical processes offer innovative solutions in waste material reclamation and integration into the production chain. These practices not only mitigate waste but also enable resource recovery, turning waste management costs into profits. Repurposing mineral waste reduces mining's environmental impact, lessens new mining needs, and yields economic advantages.

Simulation of breaching of laboratory-scale earth dams by overtopping with XBeach

Catastrophic breaches of water and mine waste retaining impoundments in recent history have emphasized the severity and consequences to the downstream environment. In this study, the applicability and suitability of the XBeach numerical model for modelling earth dam failures driven by overtopping with water is explored by detailed comparison with controlled experimental data. The XBeach model is applied to simulate laboratory-scale breaches caused by overtopping failure of dams constructed with uniform sand at the Queen's University Landslide Flume by Walsh et al. (2021a). The model sensitivity to boundary conditions for different virtual flume sizes, different sediment transport equations that influence erosion rates, and the process of avalanching are investigated. The model results are in best agreement with laboratory measurements when the Soulsby-van Rijn sediment transport formulation is used, which depends on grain size, and the avalanching module is activated, indicating the importance of these processes. The model is also run for different dam geometries to investigate the influence of upstream slope angle, which is relevant for tailings dam breach analyses. The results indicate that for flatter slopes the model is in closer agreement with observations of the peak discharge, while for steeper slopes the model results are better for breach duration time. Overall, XBeach provides promising results for the prediction of the dam breach outflow hydrograph at the laboratory scale and has potential to improve understanding of earth dam failure outcomes with further investigation.

Inhibition of pyrite oxidation through forming biogenic K-jarosite coatings to prevent acid mine drainage production

This study proposes a novel method by forming biogenic K-jarosite coatings on pyrite surfaces driven by Acidithiobacillus ferrooxidans (A. ferrooxidans) to reduce heavy metal release and prevent acid mine drainage (AMD) production. Different thicknesses of K-jarosite coatings (0.7 to 1.1 μm) were able to form on pyrite surfaces in the presence of A. ferrooxidans, which positively correlated with the initial addition of Fe2+ and K+ concentrations. The inhibiting effect of K-jarosite coatings on pyrite oxidation was studied by electrochemical measurements, chemical oxidation tests, and bio-oxidation tests. The experimental results showed that the best passivation performance was achieved when 20 mM Fe2+ and 6.7 mM K+ were initially introduced with a bacterial concentration of 4 × 108 cells·mL−1, reducing chemical and biological oxidation by 70 % and 98 %, respectively (based on the concentration of total iron dissolved into the solution by pyrite oxidation). Similarly, bio-oxidation tests of two mine waste samples also showed sound inhibition effects, which offers a preliminary demonstration of the potential applicability of this method to actual waste rock. This study presents a new perspective on passivating the oxidation of metal sulfide tailings or waste and preventing AMD.