Waste Tailings Research Articles

Mineralogical Characterization of the Grot Lead and Zinc Mine Tailings from Aspects of Their Further Use as Raw Material

The possibility of using waste tailings produced by flotation in the lead and zinc mine of Grot, Serbia as a potential source of secondary mineral raw materials was examined. The aim of the research was primarily to carry out a detailed characterization in order to determine the dominant minerals, and, for the first time, to trace the changes occurring in the unit cells of the minerals present in that deposit. There was also a need to determine the exact proportions of the present mineral phases for their further application and utilization as natural resources in environmental protection. Samples were taken from three different sections of tailings: the crest of dam (JKB), outlet pipe of the flotation facility (JOF) and hydrocyclone overflow (JHC). Granulometric separation was performed to facilitate the extraction of certain minerals from waste. The results showed that all samples mainly contained quartz, clinochlore, calcite, albite, pyrite and biotite, but their ratios in each sample varied significantly. After characterization, samples were separated into different fractions and their mineralogical compositions were determined. Depending on the fraction, the mineralogical compositions also changed. Mineralogy and geochemical analysis indicate that waste tailings can be used as a secondary mineral raw materials source applicable in various industries.

Enrichment of manufactured waste at the AMMC copper processing factory in Uzbekistan

This article is devoted to the additional extraction of valuable components from the waste tailings of the AMMC copper processing plant. The mineral composition of the waste tailings of the CCP is mainly represented by quartz, feldspars, sericites and, in a subordinate amount, mafic and secondary minerals. Pyrite is the most widespread ore mineral in the waste tailings of the CCP. Chalcopyrite, sphalerite, galena, molybdenite, and iron oxides are also noted. The copper content in the selected spot samples from tailings after chemical analysis averaged 0.139%. A sieve analysis was carried out to determine the granulometric composition of waste tailings, the distribution of valuable components by size classes. On the basis of the obtained results on the study of the material composition, flotation of tailings of the CCP AMMC was carried out with recleaning of the main flotation concentrate. During tailings flotation with one recleaning of the main flotation concentrate, the extraction of copper and molybdenum into the total concentrate is 56.8% and 63.8%, respectively.

Analyzing stability of protective structures as the elements of geotechnical tailing pond safety

Purpose is the assessment of soil retaining wall stability to ensure geotechnical safety during the radioactive waste tailing pond closure and further recultivation (or rehabilitation) in Kamianske town (Ukraine). Methods. Geomechanical stability of the protective structure has been assessed relying upon the analysis of geological-hydrogeological, engineering-geological, and geotechnical conditions of the certain tailing pond area using a deformation elastic-plastic model of a medium implemented on the basis of finite-element method. For the purpose, the dam slopes have been detalized taking into consideration their geometry as well as changes in vertical section of rock material characteristics in accordance with the earlier geophysical studies; exploration drilling; and engineering-geological surveys. Findings. Stability coefficients of protective tailing pond dam have been identified within the typical areas of a hydraulic structure; it provides high reliability and representativeness of the whole structure health in time as well as under various conditions of the industrial waste water saturation. It has been defined that the stability coefficients varies from ks = 1.372 to 4.758. Comparison of the indicators between 2022 and 2016 demonstrates a tendency of the slope stability coefficient decrease due to water saturation and groundwater level rise. Nevertheless, design characteristics of the structure make it possible to ensure satisfactory a stability coefficient along the whole dam length being 1.13 times higher than the standard one (i.e. ks = 1.250). Originality. The dependence of the tailing pond protective dam stability upon a water supply degree at the forecasted groundwater level rise at the expense of atmospheric and melt water ingress to the tailing pond has been defined. The danger of complete radioactive waste water saturation is a significant reduction in the stability coefficient of the protective structure, which can be supported by predictive modelling data. If strength parameters of a dam material decline for the most critical area then the strength coefficient decreases starting from 1.532 in terms of the current groundwater level down to 1.372 as for the forecasted dam water supply. The figure is more than 10% of its initial stability. Practical implications. The obtained results substantiate the necessity; moreover, they are of practical value while improving hydrological, hydrogeological, and geotechnical monitoring of the analyzed tailing pond to ensure its radiation safety under different conditions of further behaviour during closure, recultivation, or rehabilitation.

Biotesting of Binding Reagents for Dust Suppression on Rare Metal Tailings Waste in the Arctic Zone of the Russian Federation

The paper presents the results of environment safety assessment of Russian and foreign binding reagents (Syntex-65, Lukoil DD 3000, Voltes PP-300 and Dustbind) used for remediation of objects of accumulated environmental damage in the Murmansk region. The paper shows that in the presence of anti-erosion and water-retentive phytocenosis on technosoil of loparite ore tailings, these reagents have a partial inhibitory effect on the first first seedlings of timothy grass (Phleum pratense L.) and red fescue (Festuca rubra L.) and statistically (p <0.005) affect its main quality indicators (plant height and biomass). Effective methods of applying reagents to the dusty surface of technosoil were identified. When using the Lukoil DD 3000 reagent as an analogue of Dustbin – continuous, for Voltes PP-300 – fragmentary, when using Syntex-65 – continuous in the mode of simulated hydroseeding.

Efficient carbamazepine degradation by modified copper tailings and PMS system: Performance evaluation and mechanism

It is a green and sustainable path to establish cheap solid waste-based catalyst to establish peroxymonosulfate (PMS) catalytic system for the degradation of carbamazepine (CBZ) in water. In this study, durable copper tailing waste residue-based catalyst (CSWR) was prepared, and efficient CSWR/PMS system was constructed for catalytic degradation of CBZ for first time. The morphology and structure of CSWR changed from clumps to porous and loose amorphous by alkali leaching and medium temperature calcination. The reconstructed surface of the CSWR exposes more active sites promotes the catalytic reaction and increases the degradation rate of CBZ by more than 39.8 times. And the CSWR/PMS achieved a CBZ removal of nearly 99.99 % in 20 min. In particular, perovskite-type iron-calcium compounds were formed, which stimulated the production of more HO• and SO4•− in the system. DFT calculation shows that CSWR has stronger adsorption energy and electron transfer ability to PMS molecules, which improved the degradation efficiency of the system. In general, this study proposed a means of high-value waste utilization, which provided a new idea for the preparation of solid waste based environmental functional materials and is expected to be widely used in practical wastewater treatment.

Geochemical distribution and environmental assessment of potentially toxic elements in farmland soils, sediments, and tailings from phosphate industrial area (NE Algeria)

This study investigates the extent and spatial distribution of Potentially Toxic Elements (PTEs) in the Djebel Onk phosphate mine area in south-eastern Algeria, as well as the associated risks to human health. Various scales are considered and sampled, including tailing waste (n = 8), surrounding farmland soil (n = 21), and sediments (n = 5). The samples were mineralogically and chemically analyzed using XRD, FTIR, XRF, and ICP-MS techniques. Principal Component Analysis (PCA) was applied after transforming the raw data into centered-log ratios (clr) to identify the dominant factors controlling the distribution of PTEs. Furthermore, pollution assessment was conducted using several indices, including geo-accumulation, pollution load, contamination security indices, and enrichment and contamination factors. The results reveal that the analyzed samples are mostly P-enriched in the mine tailings, farmland soil, and sediments, with P2O5 concentrations ranging from 13.37 wt% to 26.17 wt%, 0.91–21.70 wt%, and 17.04–29.41 wt%, respectively. The spatial distribution of PTEs exhibits clearly a decrease in the contents of CaO, P2O5, Cr, Sr, Cd, and U with increasing distance from the mine discharge site, while other oxides, such as MgO, Al2O3, SiO2, K2O, and Fe2O3, and associated elements (Cu, Co, Pb, and Zn), show an increase. PCA confirms the influence of minerals such as, apatite, dolomite, and silicates on the distribution PTEs. It denoted that the highest contamination level of all PTEs in soils and sediments was observed in the southern part of the plant and mine tailings compared to the northern part. In terms of human health risks, the assessment reveals that the hazard index (HI) values for both non-carcinogenic and carcinogenic risks associated with PTEs in the study area are below 1, suggesting no significant risk. However, regardless of the sample type, the lifetime cancer risk (LCR) values vary from 1.69E-05–2.11E-03 and from 1.03E-04–2.27E-04 for Cr, Ni, As (children) and Cd (adults), respectively, exceeding the safe levels recommended by the United States Environmental Protection Agency. The study highlights that oral ingestion poses the greatest risk, followed by dermal contact and particle inhalation. Importantly, all these indices decrease with increasing distance from the sampling site to the waste discharge point and the factory, which indicates that the phosphate mining activity had caused some extent risks. These findings provide valuable insights for mitigating the adverse health impacts and guiding environmental management efforts.

Comparing the microbial communities in and End-pit lake, active tailings ponds and freshwater bodies from the Athabasca oil sands region

The Athabasca oil sands region in northern Alberta is home to one of the largest bitumen deposits in the world. Oil sands are mostly recovered via surface mining and the oil extraction is achieved with hot caustic water and diluents, a process that produces liquid tailings waste (CEC 2020, Schramm et al. 2000). It is estimated that 1 m3 of bitumen produces around 4 m3 of tailings, which are contained in large tailings ponds (Mikula et al. 1996). End-pit lakes are a potential strategy to reclaim mining pits created by oil sands mining. They may be formed by filling a mined-out pit with tailings and then capping it with a layer of fresh water. With time, tailings undergo a dewatering process in which they become denser and release water to the cap water (Charette et al. 2012). Base Mine Lake (BML) is the first full-scale demonstration end-pit lake in the Canadian oil sands industry. This former tailings pond was initially capped in 2012 with a 5 m layer of freshwater to allow for consolidation of the tailings and the stimulation of aerobic microbial communities to biodegrade the organic pollutants. Since its establishment, BML has been extensively monitored to assess the improvement in water quality. The present research focused on determining how the eukaryotic and bacterial communities in BML compare to those in local freshwater bodies and active tailings ponds. Eleven reference sites, including freshwater reservoirs, natural lakes, and 9- to 14-year-old excavated pits filled with water, also known as borrow pits, were sampled along with 5 active tailings ponds and BML during the summer of 2022. Microbial communities were assessed via next-generation sequencing of PCR amplicons of the 16S rRNA gene for bacteria and the 18S rRNA gene for eukaryotes. Alpha-diversity analysis of the eukaryotic communities showed that BML has greater species richness and evenness than active tailings ponds, but lower than freshwater systems. The bacterial community in both BML and active tailings ponds is dominated by Proteobacteria, but the relative abundance of Actinobacteriota is similar between BML and freshwater. Beta-diversity analysis revealed that eukaryotic and bacterial communities in BML cluster distinctly from both the freshwater controls and active tailings ponds, however, the composition of the eukaryotic community shows some overlap with certain freshwater systems (Fig. 1). The results of this research suggest that, 10 years after its formation, the microbial communities in BML are intermediate between an active tailings pond and a freshwater lake.

Estimation of vanadium removal from calcification roasting-acid leaching tailings using ultrasonic-H2C2O4 synergistic technology

Metal vanadium smelting produces roasting-acid leaching tailings containing approximately 1% vanadium residue, making it challenging to store and recycle these waste tailings in an environmentally friendly manner. To address this issue, a clean method called ultrasonic-enhanced oxalic acid complexation was proposed in this study for efficient removal of residual vanadium. Under the optimal conditions, the removal rate of vanadium and the decomposition rate of oxalic acid reached 86.88% and 23.6%. An in-depth analysis on the experimental results in combination with thermodynamics found a virtuous cycle chain induced by ultrasonic cavitation. Ultrasonic waves facilitated the decomposition of oxalic acid, producing more CO2 to supplement the limited cavitation bubble nucleuses. Consequently, the cavitation effect was strengthened, leading to an increased yield of OH radicals. This resulted in a continuous improvement in the oxidation environment. Furthermore, the enhanced virtuous cycle generated by ultrasonic cavitation produced powerful microjets that facilitated the stripping and dispersion of mineral particles. Overall, the oxalic acid-ultrasonic leaching technique offers a clean and efficient technology for separating vanadium.

Mining Waste Utilization as a Sound Absorbing Material

The bricks used for construction purposes are not able to control sound. Although the old bricks are replaced by mining waste fly ash nowadays for waste management , the use of other mining waste as bricks is also a challenging factor. Hence, in this paper experimentation is conducted to find the best noise absorbing material by using different mining waste, like tailing waste iron mines. To improve sound absorbing property, porosity and water absorption tests are also conducted by adding rice husk.

The importance of securitization in addressing environmental issue: Case on Freeport's tailing waste

Numerous environmental challenges remain unresolved in Indonesia, primarily due to a lack of understanding and limited exposure to the issue. This study discusses a particular case specific about tailing waste resulting from mining activities conducted by Freeport in Papua. This issue may persist without securitization efforts from relevant stakeholders. Interestingly, the key stakeholders in this case are the local community, diverging from the stereotype dominated by NGOs and other private actors. Additionally, this study served as a response to the scarcity of discussion securitization regarding environmental concerns in Indonesia. The research employs qualitative descriptive methods supplemented by a comprehensive literature study, drawing upon publications from the Google Scholar database related to securitization in the context of environmental issues in Indonesia. The finding will be visualized by the VosViewer program. The results of this study show the need for comprehensive discussions surrounding the Freeport tailing waste case. These findings are derived from significant keywords identified in related publications, particularly those related to securitization. In conclusion, the research highlights the importance of securitization by certain stakeholders in addressing particular environmental issues, ensuring that, they receive adequate attention and resolved by responsible actors.

Utilization of Extraction Procedures for Evaluating Environmental Risk from Waste Materials.

Several procedures for extracting content from different waste materials types were investigated, with the aim of evaluating their environmental impact. The waste materials consisted of wastes from bauxite ore processing by means of the Bayer process (red mud, Ajka, Hungary), bauxite ore using the sintering process followed by the Bayer process (brown-red mud, Žiar nad Hronom, Banská Bystrica region, Slovakia) and sulphide ores (metal-rich post-flotation tailing, Lintich, Slovakia). The extraction procedures were carried out with the aim of isolating "mobilizable" fractions using 0.05 M ethylenediaminetetraacetic acid (EDTA) and 0.43 M acetic acid (AA) (representing environmental risk during changes in normal environmental conditions) and "maximum potentially mobilizable" fractions using 2 M HNO3 (representing the total environmental risk). The content of chosen toxic heavy metals (THMs) (Cd, Cr, Cu, Pb, Ni, Zn) and Fe, Mn as metals creating Fe/Mn oxides in the extracts and solutions after microwave digestion was determined using high-resolution continuum source flame atomic absorption spectrometry (HR CS FAAS). On the basis of the results obtained in this study, it is possible to state that different origin of waste materials is reflected in different mobility of toxic heavy metals into the surrounding environment. From the point of view of toxic heavy metals mobility, disposal site of wastes after bauxite processing are much less of a threat to the environment than disposal site of flotation sludge after processing sulphide ores. The single extraction of 0.43 M AA is more effective than the extraction of 0.05 M EDTA for the purposes of determining the content of metals in the mobilizable fraction of tailing waste materials. The mobility of the studied toxic heavy metals in the Lintich tailing decreases in the direction from the lagoon to the dam, which may indicate the fact that the dam serves to a certain extent to inhibit the mobility of metals into the surrounding ecosystem.

Pollution Level, Ecological Risk Assessment and Vertical Distribution Pattern Analysis of Heavy Metals in the Tailings Dam of an Abandon Lead–Zinc Mine

Tailings dams in mining areas frequently experience the phenomenon of haphazard dumping and stacking of a large amount of tailings waste. Under the influence of surface runoff and groundwater infiltration, heavy metals from tailings waste can migrate to the surrounding areas and underground soil, resulting in extensive heavy metal pollution. To analyze the pollution level and ecological risk of heavy metals in an abandoned lead–zinc mine tailings dam, this study first employed X-ray fluorescence analysis to determine the vertical distribution patterns of heavy metals with depth. Then, the pollution levels of heavy metals were analyzed based on the Nemerow comprehensive pollution index and geoaccumulation index. Subsequently, the ecological risk of heavy metal pollution was further assessed using the potential ecological risk (PER) index. Finally, the sources and potential hazards of heavy metal pollution were investigated. The results reveal that (1) heavy metal pollutants are identified as lead (Pb), zinc (Zn), copper (Cu) and arsenic (As), displaying enrichment at the interface layer between the reclaimed zone and tailings layer with the highest concentrations; (2) the pollution degrees in each zone follow the order of interface layer > tailings layer > deep zone > reclaimed zone, and the pollution levels for the four heavy metals in decreasing order are Pb > Zn > As > Cu; (3) after considering the toxic effects of heavy metals, the potential ecological risk in each zone remains consistent with the ranking of pollution levels, and the contribution of the four heavy metals to PER changes to Pb > As > Zn > Cu, corresponding average Eri values of 913.928, 416.900, 96.462 and 47.998, respectively; (4) ecological risk of heavy metals originates from lead–zinc ore extraction, and heavy metal pollution poses potential risks to public water security and surrounding ecological resources.

Study on the Liquefaction Mechanism of Mixed-Size Tailings Material Based on Grain Contact State Theory

Tailings ponds serve as high-potential energy structures designed to store waste tailings and other industrial materials. However, they can give rise to significant environmental pollution and pose a substantial threat to social and economic development, as well as the safety of people’s lives and property. Seismic disasters can cause liquefaction of tailings, leading to destabilization and dam failure of tailings ponds, and the evolution of dynamic pore pressure of tailings can indirectly reflect the destabilization process of tailings ponds. Fine grain content is one of the main factors affecting the dynamic strength and pore pressure development of tailings. This article studies the microscopic characteristics of tailings material through microscopic observation, triaxial testing, discrete element simulation, and grain contact state theory, aiming to analyze the influence mechanism of fine grain content on the micromechanics of tailings. Based on the grain contact state theory, the tailings with different fine grain contents are classified into three types: coarse grain tailings, intermediate-size grain tailings, and fine grain tailings, and the grain contact is classified into four different states. In contact state 1, the vibration pore pressure exhibits a “fast-stable” development mode with increasing vibrations. In contact state 2 or 3, the vibration pore pressure develops linearly with vibrations. For contact state 4, the development of vibration pore pressure presents a “fast-stable-sharp” development mode. The effect of fine grain content (FC) on the liquefication of the tailings studied in the present work is as follows. When the fine grain content is FC<30%, the liquefaction resistance of the tailings decreases with the increase of FC. When FC>30%, the liquefaction resistance increases with the increase of FC. When FC=30%, the liquefaction resistance is the lowest, indicating that the critical threshold of the fine grain content of the tailings studied in the present work is FCth=30%.

Environmental contamination characteristics of heavy metals from abandoned lead–zinc mine tailings in China

China holds large-scale lead–zinc mineral resources; however, mining activities often cause severe contamination by heavy metals. This study systemically assessed contamination by eight heavy metals (Cu, Zn, Cd, Pb, Cr, Hg, Ni, and As) in mine tailings, soil, and groundwater from 27 contaminated sites across China. Regarding mine tailings, 1% of the mine tailing samples were hazardous waste and 20% were class II non-hazardous waste. Regarding soil, Zn and Pb showed the highest mean concentrations, at 5574.67 mg/kg and 2034.88 mg/kg, respectively. The indexes of geo-accumulation (Igeo) of eight heavy metals ranged from −3.62 to 7.67, while Zn, Pb, and Cd showed the highest environmental risk levels as the priority pollutants. The contamination levels of these heavy metals in groundwater were generally in the order of Zn>As>Pb>Ni>Cd>Cu>Hg>Cr. In this study, 20% of the soil and 10% of the groundwater samples exceeded the corresponding quality limits. The content of heavy metals in soil, groundwater, and mine tailing were positively correlated, demonstrating the main pollution source and transport paths. The pollution levels of heavy metals in soil and groundwater were listed in the foremost and moderate positions compared with similar sites from other countries, respectively. These results may help determine the pollution levels of lead–zinc mining regions and direct the remediation activities of target sites to support the environmental management of abandoned mining and tailing waste in China.

Efficient bio-cementation between silicate tailings and biogenic calcium carbonate: Nano-scale structure and mechanism of the interface

Biogenic calcium carbonate (bio-CaCO3) cementing tailings is an efficient technology to immobilize heavy metals in waste tailings. However, the underlying mechanism of interface cementation has not yet been clearly established, which limits the technological development. In this study, we used advanced techniques, including atomic force microscopy-based Lorentz contact resonance (AFM-LCR) spectroscopy, AFM-based nanoscale infrared (AFM-IR) spectroscopy, and solid-state nuclear magnetic resonance (ssNMR) spectroscopy, to reveal the structural, mechanical, and chemical properties of the interface on the nanoscale. Ureolytic bacteria produced bio-CaCO3 to fill in pore space and to bind cement tailings particles, which prevented the formation of leachate containing heavy metals. After cementation, a strong 40–300 nm thin interface was formed between the taillings and bio-CaCO3 particles. Unlike chemically synthesized CaCO3, bio-CaCO3 is strongly negatively charged, which gives it better adhesion ability. Fourier transform infrared (FTIR), AFM-IR, and 29Si ssNMR spectra indicated that the Si–OH and Si–O–Si groups on the silicate surface were converted to deprotonated silanol groups (≡Si–O-) at a high pH and they formed strong chemical bonds of Si–O–Ca on the interface through a Ca ion bridge. In addition, hydrogen bonding with Si–OH also played a role at the cementation interface. These findings provide the nano-scale interfacial structure and mechanism of bio-CaCO3 cementing silicate tailings and accelerate the development of tailings disposal technology.

A study on mechanical properties and permeability of steam-cured mortar with iron-copper tailings

With the development of construction industrialization, the use of steam curing to produce precast concrete is widely used. In order to recycle long-term stacked tailings waste, iron-copper tailings (ICT) waste is comprehensively utilized in steam-cured mortar (SCM). The effect of ICT substitution level on the mechanics and durability of steam-cured mortars is investigated in this study. The research results show that the use of appropriate ICT instead of river sand in the production of mortar is beneficial to the enhancement of the mechanics and durability of the mortar. When the replacement level of ICT is 10%, the 1-d and 28-d compressive strength of SCM are increased by 1.09% and 7.27% respectively compared with plain mortar. SCM mixed with 10–20% ICT has lower permeability compared to plain samples, and further increasing the substitution level of ICT is not benefit the development of mortar durability. Since ICT has better conductivity compared to river sand, it makes the resistivity of SCM decrease with the increase of ICT content. Microstructural studies show that the addition of a small amount of ICT reduces the porosity of SCM and refines its pore structure. Meanwhile, the ICT and cement matrix exhibits a more dense ITZ than the river sand and cement matrix. Recycling of ICT also shows better economic and environmental benefits in SCM. This study provides a theoretical basis for recycling composite tailings waste in prefabricated components.

Strength variation characteristics of waste tailings cemented backfill materials with ultrafine particles

This study investigates the use of self-produced solid waste in mines to backfill the goaf, with energy saving and emission reduction technology requirements. Using a relevant backfill mixing proportion test and mechanical property test, we analyzed the strength variation law of backfill materials under different concentrations and cementation powder addition. The results showed that, for backfill materials at 7 days with an ash-tailings ratio of 1:6, the strength of specimens with 52% and 49% prepared concentrations, respectively, increased by 1.361 and 1.266 times over specimens with 49% and 46% concentrations. For backfill materials with 49% prepared concentrations and ash-tailings ratios of 1:6, 1:9, and 1:12, the specimen strength of the backfill materials with ratios of 1:6 and 1:9 improved by 0.616 MPa and 0.321 MPa—109.28% and 114.6%, respectively—compared with 1:9 and 1:12 backfill materials at 60 days. It is thus evident that the quantity of binding materials added plays a critical function in improving the strength of backfill materials, and in the subsequent application of goaf backfill. The strength of backfill materials can be enhanced by improving the gradation of backfill aggregates and increasing the amount of binding materials so as to achieve cost reductions and sustainable development.

Contamination Fingerprints in an Inactive W (Sn) Mine: The Regoufe Mine Study Case (Northern Portugal)

The target of this study was the tungsten Regoufe mine, whose exploitation stopped in the 1970s. When the mine closed, an unacceptable legacy constituted of mining waste tailings and the ruins of infrastructure was left behind. This work assessed the soil, plants, and water contamination in the mining area; namely their content in potentially toxic elements (PTEs). The global impact of PTEs in the Regoufe mine surface soil points to a very high to ultrahigh degree of contamination of the area having a serious ecological risk level, mainly related to As and Cd contributions. However, establishing the direct relation between As contamination and the anthropogenic effects caused by the mining process cannot be carried out in a straightforward manner, since the soils were already enriched in metals and metalloids as a result of the geological processes that gave origin to the mineral deposits. The studies performed on the plants revealed that the PTE levels in the plants were lower than in the soil, but site-specific soil concentrations in As and Pb positively influence bioaccumulation in plants. The magnetic studies showed the presence of magnetic technogenic particles concentrated in the magnetic fraction, in the form of magnetic spherules. The magnetic technogenic particles probably result from temperature increases induced by some technological process related to ore processing/mining activity. The PTEs in the surface and groundwater samples were similar and relatively low, being unlikely to pose potential health and environmental risks. Arsenic (As) constituted the exception, with levels above reference for drinking water purposes.

Hydration characteristics of tailing mud–42.5 OPC composite cementitious system and its application to dry-mixed mortar

This study investigated the influence of the raw material ratio on the product quality of tailing mud with type-I 42.5 ordinary Portland cement (OPC) in a binary cementitious system. In particular, this research aimed to expand the applicability of tailing mud and tailing waste rock while minimizing the production cost of dry-mixed mortar. The results demonstrated a synergistic reaction between the tailing mud and 42.5 OPC, which was beneficial for enhancing hydration and gelation, increasing the production of calcium silicate hydrate (C–S–H) and calcium hydroxide (C–H), promoting more free magnesium oxide (MgO) in the cement to participate in the hydration reaction, and improving the structure of the composite gelation system. When the concentration of tailing mud in 42.5 OPC was 20%, the cementitious block attained a 28-day compressive strength of 44.85 MPa. To manufacture the dry-mixed mortar product, 80% mud and 20% 42.5 OPC were mixed with equal amounts of tailing mud and waste rock aggregate. For the dry-mixed mortar, the 28-day compressive strength was 7.32 MPa, 2-h consistency-loss rate was 12.4%, and water retention rate was 99.2%. To further explore the synergistic reaction mechanism between the tailing mud and 42.5 OPC, the energy calculations, geometric optimization, and dynamic modeling of the tailing mud–42.5 OPC cementitious system were performed using the Forcite module in Materials Studio software. Overall, the results indicated that including tailing mud improved the mechanical strength of 42.5 OPC.

Obtaining copper concentrate during iron ore processing

The data on the complex processing of iron ore from one of the deposits of the Republic of Kazakhstan, which involves several operations of wet magnetic separation with re-grinding of raw products and their subsequent refining to produce a conditioned iron concentrate with 65–66 % iron containing 79–80 % Fe and 2.2–2.5 % Si, are presented. It was found that during the magnetic enrichment of the ore under study, the copper minerals concentrate in the magnetic separation tailings and the copper content in them increases from 0.093 to 0.2 %. A scheme and reagent system have been developed for the recovery of conditioned copper concentrate from magnetically enriched tailings. To obtain copper concentrate, magnetic separation tailings are subjected to regrinding in a lime medium to a fineness of 75 % of the –0.071 mm grade. After two operations of the main copper flotation with the use of water glass, butyl xanthate and frother MIBK, waste tailings are obtained. The froth product of the first basal flotation is cleaned twice. The result is a copper concentrate containing 15.2 % copper, 26.5 % iron, 17.5 % sulfur, 3.47 % silicon, 1.4 % aluminum and 8.5 % zinc, which corresponds to the KM-7 grade according to GOST R 52998-2008. Waste tailings contain: copper 0.08 %, iron 20.1 %, sulfur 0.25 %, silicon 16.2 %, aluminum 6.4 % and zinc 0.045 %. The influence of xanthates with different length and structure of hydrocarbon radical as well as hostaflots and amyl aeroflots on the process of copper flotation is studied. The high efficiency of butyl xanthate in the flotation of copper minerals has been confirmed.