Plant Tailings Research Articles

Cancer Incidence in a Population Living Near Radioactive Waste Storage of Uranium Mining in Stepnogorsk Area, Northern Kazakhstan.

This study evaluates the impact of radioactive uranium waste storage facilities on cancer occurrence in nearby areas. Current research evaluates the effect of radioactive uranium waste storage facilities on cancer epidemiology in nearby areas. The critical area had Aqsu, Kvartsitka, Zavodskoy and Stepnogorsk cities, which are located at a less than 5 km distance to the south of the Hydrometallurgical Plant tailings dump while the control group had Akkol region in 90 km from the source. The majority of population had lived in this territory more than the 30 years. Data were obtained from the Electronic Register of Cancer Patients of the Republic of Kazakhstan from 2001-2015, and 2,271 incident cases of cancer were registered. The most frequent malignancies were observed in the digestive organs (646 cases, 28%) and respiratory and intrathoracic organs (376 cases, 17%). The proportion of digestive organ cancers was higher in the critical group (560 cases out of 1913, 29%) than in the control group (86 cases out of 358, 24%). Additionally, respiratory organ cancers were more common in men, but the cancer incidence rate ratio was higher in the critical area. Notably, the study found that the cancer incidence rate ratios decreased over time, specifically for digestive, respiratory and female genital organs and breast cancer. In conclusion, while our study highlights significant differences in cancer incidence rates and frequencies between the critical and control groups, further analytical research, incorporating age-adjustment, is needed to provide a more conclusive evaluation of the potential impact of residence in proximity to the uranium mining waste storage on cancer occurrence in the study area.

Application of Response Surface Methodology on the Optimization of Chromite Recovery from the South African Middle Group Chromite Seams

The aim of this study was to optimize the recovery of chromite from the chrome plant tailings of the South African Middle Group chromite seams using a Wilfley shaking table. The optimization process employed the response surface methodology in conjunction with the central composite design. The independent variables considered in the investigation included the tilt angle (°), sample feed rate (g/min), table vibration (Hz), water flow rate (L/H), and particle size range (µm). On the other hand, the recovery (%), grade (% Cr2O3), Cr/Fe ratio, and separation efficiency (SE) (%) were determined as the response variables. Based on the characterization results, the sample was identified as a low-grade chromite containing 19.86% Cr2O3 and 18.12% Fe2O3 with a Cr/Fe ratio of 1.07. The bulk gangue material was well-liberated and rich in MgO (10.45%), Al2O3 (12.10%), and SiO2 (33.70%). The particle size distribution of the sample was 80% passing 106 µm. The optimal values for recovery, grade, Cr/Fe ratio and SE were found to be 71.59%, 36.97% Cr2O3, 1.52 and 30% respectively. The corresponding operating conditions were a tilt angle of 5.88°, a sample feed rate of 175 g/min, a table vibration of 44.5 Hz, a water flow rate of 366.16 L/H, and a particle size range of − 106 + 53 µm.Graphical

Targeted degradation of Bisphenol A with peroxymonosulfate activated by nanoscale zero-valent iron supported on molecularly imprinted polymers

In order to address the limitation of active species being influenced by the complex water environment during the degradation of target pollutants, a catalyst called MIP-nFe0 was prepared. This catalyst consists of nanoscale zero-valent iron (nFe0) supported on molecularly imprinted polymers (MIPs) with specific recognition. It was designed for the targeted degradation of Bisphenol A (BPA) by activating peroxymonosulfate (PMS). Material characterization confirmed that nFe0 was successfully loaded onto MIPs without agglomeration and did not cause significant damage to the MIPs structure. Under specific conditions (50 mg/L BPA and 100 mg/L catalyst), PMS activation with MIP-nFe0 rapidly degraded most BPA in just 0.5 min. Competitive adsorption and degradation experiments revealed that MIP-nFe0 displayed the best adsorption (21.02 mg/g) and degradation (28.89 mg/g) efficiency for BPA compared with the control materials nFe0 and nFe0 supported on non-imprinted polymer (NIP-nFe0). MIP-nFe0 was further applied in the actual water background for BPA removal, MIP-nFe0 maintained efficient BPA removal in both river water as well as sewage plant tail water, which was significantly higher than NIP-nFe0 and nFe0. Free radical capture and quenching experiments demonstrated that active species of SO4−·, ·OH, ·O2−, and 1O2 existed in the system, with SO4−· played a major role.

Assessment of the Source of Anthropogenic Pollution Impact on the Hydro-chemical Runoff of the Main Ore Elements (Using the Example of Dumps at the Altai Mining and Processing Plant, Alei Сatchment)

The content of the main ore and associated elements in the material of the tailings of the Altai mining and processing plant, in the snow cover and surface waters of the dumps, as well as in the water filtrates of the dump material was studied. It was detected that the concentration of Cu in the substrates of the dumps of the Altai mining and processing plant varies from 970 to 7350 mg/kg and exceeds the background values of the copper content in the soils of Northwestern Altai up to 1000 times, the Pb content varies. from 850 to 2800 mg/kg and exceeds the background value up to 500 times, Zn – up to 200 times (content from 350 to 12170 mg/kg), Cd – up to 100 times. It was recorded that the Pb content in pound surface water on of tailings dumps exceeds the MPC of hazardous substances 2.5 times and is 79 μg/l, Cu – 52 times (52.3 mg/l), Zn – 250 times (254 mg/l), Cd – 940 times (0.94 mg/l). It was identified that in liquid media – lysimetric, surface and snow waters of the Altai mining and processing plant tailings pond – the ratio of pollutant concentrations to background and standards norms (Russian and foreign) is higher for more labile and easily leachable elements – cadmium and zinc. In solid components (substrates, snow dust), the concentrations of copper and lead noticeably exceed the background, clarke and standard concentrations.

Study on the setting characteristics of filling slurry with different aggregate combinations

To grasp the phase change characteristics of the filling slurry from fluid to solid state in time, conducted a study on the setting characteristics of the filling slurry with different aggregate combinations, and analyzed the law of the initial and final setting time with the change of the amount of cementation powder, filling plant tailings, tailing pond tailings, and water. The results show that the initial and final setting time of the filling slurry prepared from the tailings of the filling plant is proportional to the concentration, and is positively correlated with the slope decline of the sand-cement ratio. The filling slurry prepared from the tailings of the tailing pond shows roughly the same change trend as the above slurry, but the change law is not obvious, which cannot be expressed by one kind of functional model, and the initial setting time and final setting time are less than the above slurry, which is because the tailings of the tailing pond contain more fine particles, which play a role in delaying setting in the slurry. For example, for five kinds of filling materials with different aggregates of 4:1, 6:1, 8:1, 12:1, and 20:1 sand-to-ash ratios and concentrations of 66%–72%, the initial setting times of filling slurry prepared from tailings of filling plant and tailings of tailing pond were 75.3 h–112.3 h, 77.6 h–122.2 h, and the final setting times were 82.8 h–123.4 h, 85.5 h–133.9 h. Therefore, it shows that the use of filling plant tailings containing fewer fine particles to prepare filling slurry can obtain a better treatment effect of the mining area, and the shortening of the solidification and hardening process of filling slurry can accelerate the mining cycle operation, and increase the amount of solid waste disposal per unit time, thus creating the necessary technical conditions for the enterprise to improve production efficiency and sustainable development.

Nonlinear model predictive control for improved water recovery and throughput stability for tailings reprocessing

The reprocessing of tailings aims to recover residual wealth, reclaim or rehabilitate valuable land, or mitigate safety and environmental risks. These aims all support environmental, social, and governance measures that are increasingly placed at the centre of corporate strategy. Tailings reprocessing operations are water intensive, and typically include surge tanks with both level and density averaging objectives to improve the efficiency of downstream water and mineral recovery. In this study, a rigorous dynamic model is derived to describe the rate of change of both the volume and density in these surge tanks. By simulation with industrial data it is demonstrated that the significant input disturbances typical to tailings reprocessing circuits drive a gain inversion in the density model of the surge tank. Since conventional linear averaging control approaches are not ideally suited to deal with gain inversion and multivariable control objectives a nonlinear model predictive controller (NMPC) was derived and implemented on an industrial tailings reprocessing surge tank. Results show a 5 % improvement in water recovery from the plant tailings product, and a 27 % reduction in the standard deviation of the tailings product mass flow.

How does sponge city construction affect carbon emission from integrated urban drainage system?

The integrated urban drainage system has complicated sources of greenhouse gases (GHG) emissions, which is one of contribute to climate change. As a new model of low-carbon ecological city development in China, sponge city has great potential of carbon emission reduction. However, limited by the lack of awareness of the importance of carbon emissions from integrated urban drainage system, few studies have focused on the impact of sponge city construction on the carbon emissions from integrated urban drainage system. This study proposed an accounting framework for carbon emissions from integrated urban drainage system. The emission factor method was used to calculate carbon emissions. A case study was conducted in Xiamen, China, the carbon emission level of integrated urban drainage system and the carbon emission reduction effect of sponge city construction were discussed. The results show that the carbon emission from traditional city drainage system and sponge city drainage system accounts for about 3.4% and 1.7% of the city's carbon emission, respectively. Wastewater treatment and Sludge Treatment and Disposal are the main contributors to the carbon emissions from integrated urban drainage system. Electricity consumption is the main contributors to the indirect carbon emissions. Adjusting the sludge disposal method has the best carbon emission reduction effect, raising the standard of wastewater treatment plant tail water will lead to an increase in carbon emissions. Compared with the traditional city drainage system, the sponge city drainage system can reduce carbon emissions from integrated urban drainage system by an average of 49%, and the corresponding economic benefit was approximately 91–297 CNY/104 m3 wastewater. This study plays a positive role in understanding the carbon emission level of integrated urban drainage system and planning the low-carbon development of the city in the future.

Investigation of chromite recovery possibilities from coarse and fine plant tailings

Tailing streams of an existing chromite plant were characterized and then beneficiated in different methods. Characterization studies have been indicated that chromite grains finely disseminated on the coarse gangue particles in all size fractions (+100 µm). Increase in fineness did not show a significant effect on disseminated chromite grains during coarse tailing beneficiation studies. Neither a salable concentrate nor an acceptable recovery could not be obtained from coarse tailing. For this reason, optimization studies were focused on fine tailing sample. Removal of the gangue minerals was determined to be more efficient using gravity concentration rather than magnetic separation. The effect of parameters of shaking table were optimized using empirical models. It was determined that grade and recovery in the concentrate majorly depended on the variation of table slope. To achieve high grade (>42%) with acceptable recovery (>40%), a medium level of wash water (>4lpm) and lower level of table slope (

Restoration of Biological Potential in the Territory of the Gold-Processing Plant Tailings Storage Facility

The features of the impact on the natural environment of the gold-processing plant tailing dump are considered. The factors that slow down the natural recovery of disturbed areas have been revealed. Attention is drawn to the fact that it is necessary to carry out a biological stage of land recultivaiton with respect to the natural-geographical and socio-economic conditions of the area where the gold-processing plant is located in order to restore the productivity of disturbed lands. An algorithm of plants selection for biological recultivaiton is presented. The factors that can affect the successful reforestation of the area are specified.

Photocatalytic degradation of xanthate in flotation plant tailings by TiO2/graphene nanocomposites

• TiO 2 /G photocatalytic catalyst was prepared through a hydrothermal method. • TiO 2 /G catalyst was applied for the treatment of mineral processing wastewater. • 18% TiO 2 /G showed superior photocatalytic performance than TiO 2 . This study has invented a novel composite photocatalytic material of TiO 2 /graphene (TiO 2 /G) via the hydrothermal method. The prepared TiO 2 /graphene (TiO 2 /G) composite catalysts were investigated in detail using various characterisation experiments. The characterisation experiments indicated that the TiO 2 /graphene (TiO 2 /G) nanocomposites were successfully prepared. It can be observed that the TiO 2 nanoparticles were observed uniformly distributing on the graphene oxide (GO) and the prepared TiO 2 /graphene (TiO 2 /G) nanocomposites possess huge specific surface area, small pore size, and low electron-hole pair complexation rate to degrade the pollutants. For the first time, TiO 2 /G is used as a photocatalytic material to treat mineral processing wastewater. Compared to GO and TiO 2 , under simulated light irradiation, the photodegradation efficiency of 18% TiO 2 /G samples reached 97.03% after 100 min. By successfully anchoring TiO 2 on GO, the photoresponse range of TiO 2 /G was broadened (from 200–380 nm to 200–800 nm). The activity was also further improved (after 100 min of simulated light, the photocatalytic efficiency of pure TiO 2 was only 17.88%, and the photocatalytic efficiency of 18% TiO 2 /G was 5.43 times higher than that of pure TiO 2 ). This work advances the development of a potential photo-, photoelectro-systems for the treatment of real mineral processing wastewater.

Magnetization roasting of waste iron ore beneficiation plant tailings using sawdust biomass; A novel approach to produce metallurgical grade pellets

Minerals recovery and recycling of valuables from industrial waste using biomass (renewable energy resource) is the need of the hour for mineral-rich countries worldwide. Moreover, growing steel demand and fossil fuel consumption led civilization to ponder the alternative raw materials and energy sources apart from conventional coal/coke as an appropriate reductant for the iron and steelmaking process. Therefore, the generated waste iron ore beneficiation plant tailings (IOBPT) containing 56.96% Fe(T), 4.07% Al2O3, 7.23% SiO2 and 4.38% of LOI (contributed mainly from clay and goethite) can be considered a potential secondary mineral resource consumed in the downstream iron making processes. In the current investigation, a novel approach of magnetization roasting of the IOBPT using sawdust biomass (SDB) (generated from the sawmill) as a carbonaceous solid reductant is used to recover the pellet grade magnetite concentrate. On the other hand, the IOBPT was directly subjected to a wet high-intensity magnetic separator (WHIMS) to compare the generated pellet grade concentrate in both methods. In this regard, the quality of the concentrate and indurated pellets obtained from both processes was characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), wet chemical analysis, and X-ray microtomography (X-ray microCT), respectively. Altogether, the innovative way of utilizing SDB as a suitable reductant in magnetization roasting at 950 °C to produce metallurgical grade pellets (CCS:258 kg/pellet, Porosity:25.68%, RI:0.71%/min at Rt = 60, RDI-2:RDI]-2.8 = 2.61%, FSI:19.05%) indicates towards a fossil fuel-free industrialization.

An Urban Water Pollution Model for Wuhu City

An in-depth study of the temporal and spatial distribution of pollution loads can assist in the development of water pollution remediation. The research scope of this paper was the highly developed Wuhu City located south of the Yangtze River. Chemical oxygen demand (COD), NH3-H, and total phosphorus (TP) were chosen as the pollutant research objects of this study. Then, by combining the natural and social conditions within the scope of the study, a balanced system of pollution load generation and migration was described. A pollution load model of Wuhu City based on Load Calculator, MIKE 11, and ArcGIS was established. The results indicate that, in terms of the time distribution, the changes in the influx of the different pollutants were consistent. In terms of the spatial distribution, the major contributions to the annual pollution load were domestic pollution, urban surface runoff pollution, and poultry breeding pollution. The major contributors to the annual pollution load into the river were domestic pollution, urban surface runoff pollution, and sewage plant tail water pollution. This analysis provides references for the comprehensive management of local water environments.

Optimization of Line of Magnetite Recovery from Wet Tailings by Creating Second Medium Intensity Magnetic Field (Case Study: Processing Plant of Gol-e-Gohar Hematite)

The primary raw material of the steel industry is iron. This paper aims to optimize magnetite recovery from wet tailings by increasing the iron content in the concentrate of the line. To manage tailings, a Wet Tailing Processing (WTP) line constructed at Gol-e-Gohar Iron Ore Company to recover the magnetite. The dominant crystalline phases in these tailings were quartz, albite, talc, hematite, and calcite. The line feed is 45 microns, which is not suitable for the gravity method. Thus, separation can achieve using only the magnetic method. Because of the high iron content in the tailings, a wet magnetic separator is used. According to the results, the proposed medium-intensity separator and the associated circuit modifications increase iron recovery from 7 to 30 percent; resulting in 150 tons of annual production; preventing loss of iron through concentrator plant tailings, and increasing the Blain number by 50 to 100 units in the hematite plant. Furthermore, water consumption is significantly reduced by replacing old wet tailings of the concentrator plant with new wet tailings as the feed, which is another significant achievement of this research. Instead of fresh water, saline water with flow rate of 250 cubic meters per hour are used.

Production of electrolytic copper from Zhezkazgan Processing Plant tailings leaching solutions using a hydro-impulse discharge

In this work, for the first time, studies of the mineralogical composition and chemical semi-quantitative spectral analysis (SQSA) of the Zhezkazgan processing plant tailings before and after leaching were carried out. It was found that copper is present in the tailings in the form of the chalcosine and bornite minerals. After leaching with the use of ammonium bifluoride and a hydro-pulse discharge, chalcosine and boronite are destroyed, and copper passes into a solution containing phosphoric acid. As a result of multiple placing of tailings into the solution, the copper content in it is brought to a concentration at which copper deposition on a stainless steel plate is possible. The identification of copper was implemented on a LAES-Matrix grain spectrometer. A visual comparative analysis of the changes in the structure of the treated ore waste was carried out using a TESCAN MIRA scanning electron microscope. Metallic copper was obtained from solution by electrochemical reactions in an experimental laboratory setup as a result. The technology was developed on an experimental laboratory setup for the extraction of metallic copper and brought the choice of the solution medium and electrochemical processes to the stage of obtaining the target metal with a purity of 99.99 %

Zinc Recovery from Wulagen Sulfide Flotation Plant Tail by Applying Ether Amine Organic Collectors.

Separating oxidized zinc minerals from flotation tailings is always a challenge. In this study, a flotation tailing from Wulagen zinc mine in China (Zn grade < 1%) was processed using froth flotation with combinations of amines (OPA 10, OPA 1214, OPA 13, DDA) and Na2S to study the effects of these amines on the zinc recovery as well as their interactions with other reagents, aiming to screen out a proper reagent scheme to improve zinc separation from extremely low-grade zinc flotation tailings. The results show that different amines led to different flotation performance, and the collectors were ranked as OPA 1214, OPA 13, OPA 10 and DDA in a decreasing order based on flotation collectivity and selectivity. An increase in the concentration of each collector increased the zinc recovery but reduced the concentrate zinc grade. Interactions were also observed between different amines and Na2S and Na2SiO3, and OPA 1214 outdid the others in saving the usage of both the Na2S and Na2SiO3. The measured adsorption of collector onto smithsonite was found to correlate well with flotation test results. It was concluded that hydrocarbon chains can be held accountable for the difference in the flotation performance with different amines. The longer the hydrocarbon chain, the stronger the hydrophobic association ability of amine, which is conducive to the selective amine adsorption onto sulfurized smithsonite particles and hence the smithsonite flotation.

Recovery of bauxite ore particles -1mm from tailings of the Tan Rai bauxite processing plant by mechianical classifiers

Tailings of the Tan Rai bauxite mineral processing plant contain a relatively high proportion of fine bauxite ore particles of less than 1mm. This amount of discarded fine bauxite particles necessarily leads to a high loss of valuable bauxite mineral and also require more tailings dam space. Recovery of such fine bauxite ore particles may produce certain economic and environmental effects to the current processing plant. The paper presents results of the study on recovery of fine bauxite ore particles -1 mm from tailings of the Tan Rai - Lam Dong bauxite mineral processing plant by the use of mechanical classifiers. The obtained +0.5 mm bauxite concentrate are suitable for blending with the +1 mm concentrate of the current plant. The study results showed that recovery of fine bauxite ore particles -1mm from the plant tailings may produce additional amount of valuable concentrate to ensure the supply requirements to the alumina plant and also add some values to the effective mineral resource utilization and bring some economic efficiency.

Removal of cyanide from the gold cyanidation plant tailings using graphene-based magnetic nanocomposites

Removal of cyanide from the gold cyanidation plant tailings using graphene-based magnetic nanocomposites

Evaluation of the inhibiting effect of H2O, O2, and NO on the performance of laboratory and pilot K-ZnxCo3-xO4 catalysts supported on α-Al2O3 for low-temperature N2O decomposition

The K-ZnxCo3-xO4 catalyst supported on α-Al2O3 for N2O decomposition was investigated in terms of its resistance towards typical contaminants (O2, H2O, and NO) present in the nitric acid plant tail gases. The catalyst synthesized in laboratory-scale was thoroughly characterized by means of X-ray μ-tomography, XRF, XRD, and SEM/TEM/EDX. The impact of contaminants such as O2, H2O, and NO on the N2O conversion of the catalyst was examined and quantified by kinetic and thermodynamic modeling. The mechanism of inhibition involving local (active site blocking) and global (modification of the spinel electronic properties by electrophilic NOx adspecies) effects was proposed. The strongest inhibition of NO was associated with its facile reactivity with surface O intermediates produced during N2O decomposition. The resultant NO2 and NO3 surface adducts are stable at the catalyst surface up to 550 °C. For the pilot catalyst, the effect of contamination was the same in nature as for the laboratory sample, however, the observed quantitative differences were associated with the changes in the shape of the spinel nanocrystals constituting the catalyst active phase. The obtained results provide rationales for designing and preparation of the robust deN2O catalyst with enhanced resistivity to poisoning.

Investment appeal assessment of Pt-rich and Cu-Ni deposits of Monchegorsky ore district in current conditions

Development potential and investment attractiveness of PGM deposits (Monchegorsky ore district) are discussed. By the late 2020, the reserves of these deposits were approved based on results of a feasibility study review assessment in the State Reserve Commission and TsNIGRI approval. In current mineral market conditions (including high Pd price), the most attractive development projects are Vuruchuaivench deposit comprising 4 areas (Plast 300, Vuruchuaivench, Yuzhnosopchinsky and Arvarench), NittisKumuzhya-Travyanaya occurrence and Loipishnyun area. In terms of reserves, ore grades and proximity to processing plants, these potential mining projects are less expensive if developed concurrently. The paper presents recommendations for PGM deposit opening, development and mining using advanced mining equipment in open-pit and underground mining operations, ore conveying and processing plant tailings disposal to infill underground workings. Economic estimates were made supporting development viability of the above deposits within Monchegorsky ore district.

Floc structure and dewatering performance of kaolin treated with cationic polyacrylamide degraded by hydrodynamic cavitation

At present, efficient dewatering of mineral-processing–plant tailings still presents a serious challenge, especially for tailings with a high proportion of clay minerals. In this study, cationic polyacrylamide (CPAM) was degraded using hydrodynamic cavitation and was used for the flocculation and dewatering of kaolin. The properties of CPAM after degradation were characterized using a rheometer. At the same time, focused beam reflectance measurement, particle video microscopy, and low-field nuclear magnetic resonance were used to study the flocculation and filtration characteristics of kaolin treated by degraded CPAM. The results showed that with an increase in the cavitation time, the viscosity of CPAM decreases gradually and a flocculant mixture system with multimolecular weight is formed. In the process of kaolin flocculation, the pretreated CPAM makes the flocs smaller and denser, resulting in the acceleration of kaolin filtration.