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This study aimed at the investigation of the effect of colloidal magnetic particles on the magnetic separation of iron ore tailings (IOT). For this, the synthesis and characterization of bare iron, iron-dextran, and iron-oleate magnetic particles is reported. FTIR spectra confirmed that the synthesized particles were composed by magnetite. In general, the iron recovery was superior when magnetic particles were introduced, regardless of the addition of bare magnetic or functionalized iron particles. When iron-crosslinked-dextran particles were added into the pulp at the dosages of 0.5 and 1.0 g/t, an increase in recovery of about 7% took place at 0.34 T, but with a loss in grade of about 5%. Further cleaning stages are necessary to reduce the silica content. This work is aligned with the sustainability needs of mining operations, constituting an alternative technology for the reuse of iron ore tailings. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the use of commercial tannin derivatives, namely, tannin 1 (CT1), tannin 2 (CT2), tannin 3 (CT3), and extract of tannin produced from angico bark, as aggregation agent in hematite–silica systems. Hematite and quartz were used in aggregation tests at dosages of 1, 10, and 100 mg/L at pH values of 6–9. The zeta potential and Jar tests were conducted in the best conditions of aggregation tests. The condensed tannin content of the commercial reagents is approximately similar, and it exceeds the content found in the extract obtained from angico bark. CT3 demonstrated superior percentages of sedimented material for both minerals at a dosage of 10 mg/L and pH 7 (97.12% and 95.68% for hematite and quartz, respectively). The aggregation agent produced from the angico bark displayed good sedimentation results for hematite (>90%); however, the results for quartz were unsatisfactory. The isoelectric point shifts to pH 8 when each mineral was conditioned with CT3. The jar test revealed higher sedimentation of the compositions for the lowest velocity gradient (60 rpm) with low turbidity values in the supernatant; however, the lowest turbidity (24.71 NTU) is observed in the sample with a higher percentage of hematite. [ABSTRACT FROM AUTHOR]

The water retention capacity of porous materials is crucial in various geotechnical and environmental engineering applications such as slope stability analysis, landfill management, and mining operations. Filtered tailings stacks are considered an alternative to traditional tailings dams. Nevertheless, the mechanical behaviour and stability of the material under different water content conditions are of concern because these stacks can reach considerable heights. The water behaviour in these structures is poorly understood, particularly the effects of the water content on the stability and potential for liquefaction of the stacks. This study aims to investigate the water retention and flow characteristics of compacted iron ore tailings in high columns to better understand their hydromechanical behaviour. The research used 5 m high columns filled with iron ore tailings from the Quadrilátero Ferrífero region in Minas Gerais, Brazil. The columns were prepared in layers, compacted, and instrumented with moisture content sensors and suction sensors to monitor the water movement during various stages of saturation, drainage, infiltration, and evaporation. The sensors provided consistent data and revealed that the tailings exhibited high drainage capacity. The moisture content and suction profiles were effectively established over time and revealed the dynamic water retention behaviour. The comparison of the data with the theoretical soil water retention curve (SWRC) demonstrated a good correlation which indicates that there was no hysteresis in the material response. The study concludes that the column setup effectively captures the water retention and flow characteristics of compacted tailings and provides valuable insights for the hydromechanical analysis of filtered tailings stacks. These findings can significantly help improve numerical models, calibrate material parameters, and contribute to the safer and more efficient management of tailings storage facilities. [ABSTRACT FROM AUTHOR]

This is an article in the field of ceramics and composites. In this article, the effects of IOT and polyvinyl alcohol (PVA) fiber (PF) on the compressive strength, four-point flexural strength, flexural toughness, pore structure of cement-based composites were studied and discussed in detail. The conversion relationship between compressive strength and four-point flexural strength was established. The results showed that the incorporation of IOT had an enhanced effect on the mechanical properties, and this enhanced effect showed a trend of first increasing and then decreasing with the increase in the substitution rate of IOT. However, when PF was added, the mechanical properties under the combined effect of PF and IOT were further improved and showed good toughness. In addition, the internal pores of the matrix with IOT substitution rate of 40% and PF were obviously reduced. Thus, it was concluded that the cement-based composite material had good mechanical properties when the 40% IOT was combined with PF.

Copyright of Multipurpose Utilization of Mineral Resources / Kuangchan Zonghe Liyong is the property of Multipurpose Utilization of Mineral Resources 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.)

The preparation of iron ore tailings (IOTs) into supplementary cementitious materials (SCMs) is an effective approach to achieve value-added utilization of industrial solid waste. This study systematically investigates the hydration pattern and strength development of Portland cement systems with the incorporation of IOTs, steel slag (SS), granulated blast-furnace slag (GBFS), and fly ash (FA) under the action of different chemical additives. The hydration products, and microstructure and pore structure of the SCMs are analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mercury intrusion porosimetry. The findings of this study demonstrate that chemical activation plays a significant role in the strength development of SCMs. Among the five chemical activators tested, Triethanolamine (TEA) had the greatest influence on mechanical properties. The maximum compressive strength of the SCMs at 28 days was 42.9 MPa at a dosage of 1%. Specifically, the addition of TEA promotes volcanic ash reactions, and the high fineness of SCM provides nucleation sites for hydration products. Interactions between the volcanic ash reaction and the complexation reaction of TEA have a positive effect on compressive strength development. This research expands the potential for IOTs SCMs through chemical activation methods for value-added applications. [ABSTRACT FROM AUTHOR]

The water retention capacity of porous materials is crucial in various geotechnical and environmental engineering applications such as slope stability analysis, landfill management, and mining operations. Filtered tailings stacks are considered an alternative to traditional tailings dams. Nevertheless, the mechanical behaviour and stability of the material under different water content conditions are of concern because these stacks can reach considerable heights. The water behaviour in these structures is poorly understood, particularly the effects of the water content on the stability and potential for liquefaction of the stacks. This study aims to investigate the water retention and flow characteristics of compacted iron ore tailings in high columns to better understand their hydromechanical behaviour. The research used 5 m high columns filled with iron ore tailings from the Quadrilátero Ferrífero region in Minas Gerais, Brazil. The columns were prepared in layers, compacted, and instrumented with moisture content sensors and suction sensors to monitor the water movement during various stages of saturation, drainage, infiltration, and evaporation. The sensors provided consistent data and revealed that the tailings exhibited high drainage capacity. The moisture content and suction profiles were effectively established over time and revealed the dynamic water retention behaviour. The comparison of the data with the theoretical soil water retention curve (SWRC) demonstrated a good correlation which indicates that there was no hysteresis in the material response. The study concludes that the column setup effectively captures the water retention and flow characteristics of compacted tailings and provides valuable insights for the hydromechanical analysis of filtered tailings stacks. These findings can significantly help improve numerical models, calibrate material parameters, and contribute to the safer and more efficient management of tailings storage facilities.

The preparation of iron ore tailings (IOTs) into supplementary cementitious materials (SCMs) is an effective approach to achieve value-added utilization of industrial solid waste. This study systematically investigates the hydration pattern and strength development of Portland cement systems with the incorporation of IOTs, steel slag (SS), granulated blast-furnace slag (GBFS), and fly ash (FA) under the action of different chemical additives. The hydration products, and microstructure and pore structure of the SCMs are analyzed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and mercury intrusion porosimetry. The findings of this study demonstrate that chemical activation plays a significant role in the strength development of SCMs. Among the five chemical activators tested, Triethanolamine (TEA) had the greatest influence on mechanical properties. The maximum compressive strength of the SCMs at 28 days was 42.9 MPa at a dosage of 1%. Specifically, the addition of TEA promotes volcanic ash reactions, and the high fineness of SCM provides nucleation sites for hydration products. Interactions between the volcanic ash reaction and the complexation reaction of TEA have a positive effect on compressive strength development. This research expands the potential for IOTs SCMs through chemical activation methods for value-added applications.

High-silicon iron ore tailing is typically regarded as abundant mining waste of little use; it occupies a vast area of land and is harmful to human health and the ecological environment. Nevertheless, high-silicon iron ore tailing contains abundant quartz resource. In this study, a superconducting high gradient magnetic separation (S-HGMS) coupling fluorine-free mixed acid leaching technology was used to prepare high-purity quartz from high-silicon iron ore tailing. The S-HGMS technology was applied to separate and extract quartz from high-silicon iron ore tailing. Subsequently, the obtained quartz concentrate was subjected to an acid mixture leaching procedure to extract its impurities and obtain high-purity quartz. The optimal conditions determined for the magnetic separation process were a solid concentration of 4% and slurry flow velocity of 0.12 m/s. Under these conditions, the SiO 2 grade of the quartz concentrate reached 98.56 ± 0.13%, and the SiO 2 recovery was 60.59 ± 0.13%. The optimal conditions of the leaching process were a solid–liquid ratio of 1:4, leaching temperature of 80 °C, reaction time of 10 h, and acid mixture of HNO 3 , HCl, and H 2 SO 4 (molarity ratio of 1:4:1). Under these conditions, the SiO 2 purity reached a maximum value of 99.92 ± 0.01% in the high-purity quartz. Furthermore, we proposed a process for evaluating the recovery potential of Fe from iron-rich substances and recycling the leaching solution. The applied technology achieved a comprehensive utilization of high-silicon iron ore tailing and no waste discharge, meanwhile provides a theoretical basis and data support for its industrialization. [ABSTRACT FROM AUTHOR]

In this study, a type of fly ash and iron tailing powder were used as a binary supplementary cementitious material (SCM) and two different mechanically activated procedures, named coalescent activation and separated activation, were carried out to improve the pozzolanic reactivity. Then, three binary supplementary cementitious materials were used to replace 30 wt% of ordinary Portland cement to develop cemented mortars, and the compressive strength, hydration products, and micro-structure were studied. The experimental results indicated that the activated supplementary cementitious materials increased the compressive strengths of the mortars by 5.4% and 13.2%, negligibly changed the hydration product types, and impacted the quantity only. The application of SCMs also prolonged the setting time and decreased the hydration rate, profiting the application. Simultaneously, the micro-pore structure was ameliorated, and the porosity decreased. Therefore, comprehensively considering the improved mechanical behavior and inexpensive cost, the activated binary SCM can be considered an ecological and economical admixture, especially for the coalescent activation procedure. [ABSTRACT FROM AUTHOR]

The aim of this research is to test the characteristics of concrete by substitute fine aggregate with iron ore tailings and partial glass powder as in the place of cement. Concrete with waste products such as glass powder and iron ore tailings offers technical, economic and environmental advantages. In this experimental investigation, glass powder is replaced with cement by 10%, 20% and 30% and iron ore tailings with fine aggregates by 30% which is the optimum percentage. To study the role of glass powder and iron ore tailings combination in concrete, The properties such compressive strength, flexural strength, tensile strength and also durability parameters likely water absorption investigation for M40 concrete is carried out with different percentages of glass powder by keeping the iron ore tailings percentage constant. At 30% glass powder substitution as cement and sand with IOT increases concrete effectiveness. The concrete with 10% glass powder & 30% iron ore tailings showed a higher strength compared to the conventional mix for 28 days. Concrete mix containing 10% GP and 30% IOT showed higher flexural strength of 5.05 MPa for 28 days. Splitting tensile strength value is also increasing i. e for 10% glass powder and 30% IOT, obtained splitting tensile strength was 4.48 MPa and modulus of elasticity value was has also increased. Water absorption experiment consequences results that water absorption decreases with an increase in GP percentage. The concrete workability tends to decrease when with glass powder content increase. Concrete containing 10% glass powder and 30% IOT showed maximum strength and it is considered as the optimum dosage. [ABSTRACT FROM AUTHOR]

Abstract Artificial stone materials (ASM) were produced with an iron ore tailing (IOT) from the disruption of Fundão’s tailing dam, located in Mariana, Minas Gerais State, Brazil. The IOT was separated in 3 powders with different particle sizes: DAG (

This study reports the high-yield, “in-situ” growth of multi-walled carbon nanotubes on iron ore tailing. The final product is a pioneering approach on the use of nanostructured tailing to produce mortar with improved mechanical properties in a simple, effective methodology. Four different high-yield catalysts were developed to identify the most efficient parameters for the synthesis of carbon nanotubes (CNT) via Chemical Vapor Deposition on iron ore tailing (IOT). The process yields 1800% in carbon mass, an unprecedented result. Nanostructured IOT was used to produce mortar with different CNT quantities, including concentrations highly above the limits found in the literature, and resulted in increases of in flexural strength (up to 30%). Water loss after thermal treatment, consistency index and water absorption as a function of the CNT concentration in the mortar mass were also investigated. The proposed method delineates a viable way of incorporating CNT-reinforced macromaterials into cementitious matrices without functionalization, additives, or surfactants, which represents an advance for the nanocomposites industry. It also contributes to social and environmental development by aggregating value to iron ore tailing that would be otherwise stored in huge, and sometimes dangerous, disposal dams.

Aluminium metal matrix composites are mostly consume in technological and innovative field. In this research work, Hybrid Aluminium metal matrix composite were developed by using Rice husk ash (RHA) with Iron Ore tailing (IOT) as reinforced element through stir casting process. RHA and IOT used as reinforcement by varying weight percentage of 5 to 15 wt% and its mechanical behaviour like density, porosity, harness, tensile and compressive properties was examined. From the mechanical test result, it is found tensile strength, hardness and compressive strength value increased and tensile strain and density value decreases with increasing amount of reinforcement. Tensile strength value increased by minimum 50 % to maximum 100% and hardness value also increased by up to 43% compare with unreinforced aluminium composite. porosity of composite material vary from 1.92 % to 4% which is acceptable to develop dense composite material. Therefore combination of bio waste (RHA) and industrial waste (IOT) serve great promise to replace conventional ceramic materials as reinforcement for improvement of cost effective metal composite material by utilizing waste material as wealth. [ABSTRACT FROM AUTHOR]

• A functional value-added utilization method of iron ore tailing (IOT) was proposed. • Manganese silicate (MS) composites were first synthesized by solid waste IOT. • The structure transformation from IOT to MS composites was researched. • The target of "using waste to treat waste" was achieved. Iron ore tailing (IOT) as a solid waste has attracted attention worldwide owing to the potential safety hazards and waste of resources. However, few studies focused on exploiting the structural characteristics of IOT. IOT is a special silicate mineral mixture composed of, for example, quartz, anorthite, microcline, and clinochlore which contain adjustable silica tetrahedron structures. In our research, Mn2+ was introduced to hydrothermally react with the adjustable silica tetrahedrons of IOT with the aid of sodium silicate, to provide IOT with reactive Mn-OH groups and high specific surface areas by constructing functional value-added mesoporous manganese silicate (MS) composites. It was found that the specific surface area (S BET) of IOT improved from 6.3 to 448.2 m2g−1 and achieved ideal pore size distributions after being transformed into MS composites. The composite obtained exhibited an excellent selective adsorption performance that could rapidly remove 100% methylene blue (MB) molecules from the mixed cationic dye solutions within 1 min. The adsorption behavior was well described by pseudo second-order model and Freundlich isotherm model, indicating the chemical adsorption and multi-layer adsorption. The maximum adsorption capacity was up to 217 mg g−1 (25 °C, pH = 7, adsorption time: 120 min, MB initial concentration: 400 mg L−1). Through investigation, it was found that the selective adsorptive ability is based on the hydrogen bonding and the suitable mesoporous structure for MB molecules. [ABSTRACT FROM AUTHOR]

The high density or large size grains are proposed to be added as ballasting particles to achieve a high settling rate and low supernatant turbidity for fine particle flocs during the settlement of ore tailings. Settling tests on iron ore tailings were carried out to evaluate the effects of size, density, and dosage of ballasting particles on initial settling rate and turbidity. The results showed that low density (2.65 g/cm3) particles and medium density (4.67 g/cm3) particles contributed to the increase in settling rate of the tailing slurry at all size fractions from 0.074 to 0.5 mm, with the peak performance obtained between 0.125–0.2 mm, whereas high density (6.14 g/cm3) particles only accelerated the process with the particle size not larger than 0.2 mm. It is supposed that there is a close relationship between ballasting particle properties and floc strength. The acceleration effect dominates when flocs are strong enough to bear the ballasting particles; deceleration occurs when ballasting particles are oversize, over-density, or overdosed, causing the breakage of flocs. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica 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.)

Iron ore tailings, which are important secondary resources, have outstanding latent application value in iron recovery. In this study, a pilot-scale experiment on the iron recovery from iron ore tailings was investigated using innovative technology of pre-concentration and suspension magnetization roasting (SMR), followed by magnetic separation and flotation. An iron concentrate containing 58.67% Fe at an iron recovery of 57.82% was obtained under the optimal SMR conditions: a feed rate of 100 kg/h, roasting temperature of 530 °C, CO reducing gas of 3.5 m3/h, and N 2 fluidizing gas of 3.0 m3/h. During the SMR process, weakly magnetic hematite and siderite in the iron ore tailings were converted to strongly magnetic magnetite with an average magnetic conversion rate of 81.71%. The SMR reactor exhibited good performance with well-functioning equipment, controllable process parameters, and the production of a high-quality roasted product. This innovative SMR technology is a quantum leap in separating refractory iron ore, which opens up a new approach for the efficient recovery of iron from iron ore tailings. Unlabelled Image • A new approach for SMR was developed for efficient iron recovery from iron ore tailings. • An iron concentrate with 58.67% Fe at an iron recovery of 57.82% was obtained. • Hematite and siderite were transformed into magnetite during the SMR process. • The SMR reactor showed good performances in terms of operation, control and product. [ABSTRACT FROM AUTHOR]

The classification process in hydrocyclones is affected by many factors, with the cone angle being recognized as a critical parameter determining the classification performance. In the context of recycling iron ore tailings, this paper primarily focuses on the influence of cone angles and their combination sequences on the classification performance of quartz particles within a dual-cone hydrocyclone through numerical simulations. The upper and lower cone angles were configured in 16 combinations to assess their respective impacts on classification. The results indicate that the upper cone angle primarily governs the pressure drop and tangential velocity, thereby controlling the centrifugal intensity and cut sharpness. Furthermore, the lower cone angle plays a pivotal role in determining axial velocity and particle enrichment ratio in the lower cone, thus influencing the cut size and grade efficiency. These findings should provide valuable guidance for the design and application of compound cone hydrocyclones, depending on specific requirements. [Display omitted] • Cone angle and its combination sequence have great influence on IOT classification. • As the lower cone angle increases, the classification efficiency increases. • The upper cone angle primarily governs the centrifugal intensity and cut sharpness. • The lower cone angle exerts a greater impact on cut size and water split. • The centrifugal intensity and turbulence intensity determine classification performance. [ABSTRACT FROM AUTHOR]

The formation of water-stable, hierarchical aggregate structure is one of the critical processes in eco-engineering iron (Fe) ore tailings into soil-like medium for sustainable rehabilitation of Fe ore mine site. Through systematically comparing physical structure and mineralogical differences between Fe ore tailings' aggregates and Fe-rich native soil aggregates at a magnetite-Fe ore mine, the present study captured the microstructure, mineralogy and organic matter composition of aggregates in aged (4 years old) tailings, in comparison with those in native soils. A suite of micro-spectroscopic methods have been employed to elucidate their physical, mineralogical and morphological characteristics, including synchrotron based Fe K edge X-ray absorption fine structure spectroscopy (XAFS), and backscattered electrons (BSE)-scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). The results revealed significant differences in physical structure of aggregates in Fe ore tailings and natural soils rich in Fe, which was attributed to their different mineralogical and organic components and characteristics. Especially, it was found that the secondary Fe (oxy)hydroxides (i.e., goethite, ferrihydrite) and their interactions with Al/Si rich secondary phyllosilicates (or aluminosilicates) were required in the formation of amorphous Fe-Si-Al rich gels that acted as cementing agents for agglomerating Si-rich particles (e.g., quartz) in soil. In contrast, tailing aggregates (rich in more crystalline primary minerals such as magnetite and biotite) lacked these gels, resulting in poor stability. Comparatively, natural soil aggregates contained more recalcitrate organic carbon groups (e.g., aromatic, carboxyl and aliphatic C) than tailing aggregates, which would have also contributed to the improvement of aggregate stability through organo-mineral associations. This study has improved our understanding of key limiting geochemical factor(s) involved in the aggregation of Fe rich soils, which would provide the basis for formulating effective eco-engineering inputs to accelerate the development of soil-like structure in the Fe ore tailings for sustainable rehabilitation. • Microstructures of aggregates within Fe ore tailings and natural Fe-rich soils were distinctly different; • Soil aggregates were bound with Fe-Si-Al rich gels from interactions between Fe (oxy)hydroxides and secondary phyllosilicates; • Tailing aggregates lacked secondary phyllosilicates and functional organic groups, hindering formation of stable aggregates; • Plant root activities facilitated water-stable aggregate formation. [ABSTRACT FROM AUTHOR]

• The application of iron ore tailing as primary source material to geopolymerization. • Effect of glass wool residue as a blend for iron ore tailing-based geopolymer. • High mechanical performance at 7 days of curing was observed for the geopolymers. • Glass wool residue led to a reduction in mechanical strength. This work presents an evaluation of the application of iron ore tailing as primary precursor material to geopolymer production. Glass wool residue from the iron ore industry was also included as a blend material. Four mixtures of geopolymers were produced: one mixture using only iron ore tailing; three mixtures where the iron ore tailing was replaced by the glass wool residue, with a substitution ratio of 10%, 20% and 30% (in mass). Furthermore, three different grinding times and three NaOH solution concentration were applied. Compressive strength and flexural strength tests were performed in prismatic specimens at 7-days, and the microstructural analysis of the fragments was obtained by SEM analysis. QXRD analysis based on the Rietveld's refinement method and TG/DTA analysis was applied for all specimens. The results showed the synthesis of a zeolite phase in all specimens, and the SEM micrographs showed a transformation process of the glass wool residue. Finally, high mechanical performances were found to the iron ore tailing-based geopolymer, reaching values higher than 100 MPa for compressive strength and 20 MPa for flexural strength. The obtained values are related to the grain packing improvements, geopolymerization products, and the glass wool residue working as a supplementary precursor material to the geopolymerization reaction. The result points to the potential of iron ore tailing and glass wool residue to geopolymers studies and application. [ABSTRACT FROM AUTHOR]

Iron ore tailings (FeT) and manganese ore tailings (MnT), which are abundant and inexpensive materials that contain many trace elements, were employed for the remediation of As-contaminated soil to mitigate As accumulation in rice under greenhouse conditions. Prior to the experiments, the toxicities of both amendments were assessed with the toxicity characteristic leaching procedure (TCLP) and horizontal vibration method (HVM). Based on the assessment results, both amendments were pretreated until no As was present in the leaching solution. After application of both amendments to the soil, the soil pH increased significantly (p < 0.05). The ranges of As concentrations in husk and brown rice samples were 0.13–1.54 mg kg−1 and 0.06–0.42 mg kg−1, respectively. The lowest concentrations of As (0.06±0.02 mg kg−1) in rice grains were observed with MnT treatment, which was related to the structure and composition of MnT. There was a significant negative relationship (p < 0.05) between Mn and As in rice plants, while there was a significant positive relationship (p < 0.05) between Fe and As in rice plants as well as the ratio of Fe/Mn and As in rice plants. In conclusion, MnT could potentially be useful as an amendment to remediate As-contaminated soil and control As uptake by rice plants. [ABSTRACT FROM AUTHOR]

Iron ore tailings (FeT) and manganese ore tailings (MnT), which are abundant and inexpensive materials that contain many trace elements, were employed for the remediation of As-contaminated soil to mitigate As accumulation in rice under greenhouse conditions. Prior to the experiments, the toxicities of both amendments were assessed with the toxicity characteristic leaching procedure (TCLP) and horizontal vibration method (HVM). Based on the assessment results, both amendments were pretreated until no As was present in the leaching solution. After application of both amendments to the soil, the soil pH increased significantly (p < 0.05). The ranges of As concentrations in husk and brown rice samples were 0.13-1.54 mg kg-1 and 0.06-0.42 mg kg-1, respectively. The lowest concentrations of As (0.06±0.02 mg kg-1) in rice grains were observed with MnT treatment, which was related to the structure and composition of MnT. There was a significant negative relationship (p < 0.05) between Mn and As in rice plants, while there was a significant positive relationship (p < 0.05) between Fe and As in rice plants as well as the ratio of Fe/Mn and As in rice plants. In conclusion, MnT could potentially be useful as an amendment to remediate As-contaminated soil and control As uptake by rice plants. [ABSTRACT FROM AUTHOR]

A reliability estimate of bearing capacity values of cement-iron ore tailing treated black cotton soil was evaluated using a predictive model developed from laboratory results for specimens compacted at British Standard light, West African standard and British Standard heavy energy levels. Laboratory based geotechnical properties of the treated black cotton soil were incorporated into FORTRAN-based first-order reliability program to determine the reliability index values for the following parameters: cement content, C, Iron ore tailing content, IOT, cohesion, CO, friction angle, FA, percentage fine, PF, plasticity index, PI and unit weight, UW. Although cohesion, friction angle, plasticity index and unit weight were greatly influenced by the coefficient of variation, cement content C, IOT content IOT and percentage fine PF did not significantly affect the reliability index values. F-distribution test at 95% level of significance shows that compactive effort had significant effect on the outcome of the reliability index values. However, since reliability index (β) value of 1.0, which is considered adequate for serviceability limit state design, was not met, none of the compactive efforts could be used to model the behaviour of bearing capacity of cement-IOT treated black cotton soil. Hence, a more potent admixture should be used for improving the bearing capacity of strip foundation. [ABSTRACT FROM AUTHOR]

Studies involving tailings have raised mineral industry awareness because of its potential to increases in production as well as a reduction of the environmental liabilities. The main material of this study is an iron ore tailing from the Mineração Usiminas-MG-Brazil dam, collected through probe holes and characterized by size, chemical e mineralogical analyses. Flotation assays were also carried out, evaluating the ground corn (Flotamil75 and Flokit415) and cassava flour (FF01 and FF73) depressant action, aiming at achieving a concentrate adequate for use in the metallurgical industry. The size distribution of the tailing indicated 25% passing 10 μm and 15% above 297 μm, which was adjusted by classification and desliming. The Fe and SiO2 contents were 44.3% and 30.9%, respectively. The main mineral identified were hematite and quartz, and to a lesser extent, ferruginous earthy aggregates. In the analysis of the depressants, the cassava flour presented higher water absorption index and lower pH, compared to ground corn. The cassava flour FF73 reached the best performance in the flotation: metallurgical recovery 75.88% and 2.24% sio2 in concentrate. [ABSTRACT FROM AUTHOR]

Iron ore tailings (IOT), the predominant solid by-products of iron ore mining and refining, present significant environmental challenges due to their sheer volume. This paper endeavors to scrutinize the prospective deployment of IOT as an alternative to soft soil in the fabrication of controlled low strength materials (CLSM) for backfill applications. The flowability of the CLSM is evaluated by adjusting the IOT, soft soil, and water contents and subsequent appraisal of mechanical properties of the cured CLSM samples is performed via unconfined compressive tests, dry-wet cycles, and direct shear tests at the flowability of 20 cm. Furthermore, scanning electron microscopy and mercury intrusion porosimetry tests are deployed to investigate the impact of IOT on the microstructure of the cured CLSM. Experimental results demonstrate that an increase in IOT content considerably reduces the requisite water content to achieve a flowability of 20 cm for CLSM. Both unconfined compressive strength (UCS) and direct shear tests signal that the infusion of IOT into CLSM substantially enhances the UCS (e.g., from 200 to 440 kPa) along with improving the cohesion (e.g., from 65.9 to 103 kPa) and friction angle (e.g., from 11.5° to 16.3°) of the cured CLSM samples. The mass loss of CLSM, post dry-wet cycles, is notably mitigated, and the corresponding UCS is also bolstered by increasing the IOT content. Microstructural observations in conjunction with pore size characterizations corroborate that the strength augmentation of the CLSM mixture can be attributed to the densification of the microstructure and the proliferation of cement hydration products with increased IOT content. Consequently, this investigation sheds light on the promising potential of employing IOT as a central ingredient in CLSM production. • IOT holds potential as a primary component in CLSM production. • The incorporation of increased IOT levels reduces the water content necessary to achieve desired flowability. • The addition of IOT enhances the mechanical properties of CLSM, improving both its unconfined compressive strength and shear strength. • CLSM integrated with high IOT content exhibits superior resilience to dry-wet cycles, indicating improved durability. • Increased incorporation of IOT leads to a proliferation of cement hydration products, leading to the strength augmentation. [ABSTRACT FROM AUTHOR]

Iron ore tailing is a kind of hazardous solid waste produced by iron and steel industry. In order to separate and recycle iron from the magnetic preconcentrate of an iron ore tailing, an innovative technological route of fluidized magnetization roasting followed by low-intensity magnetic separation was proposed in this paper. The effects of roasting temperature, dosages of reducing gas CO and fluidizing gas N2 on recovery rate of iron were carried out and optimized. The results showed that the hematite was almost reduced to magnetite by a gas mixture of 4 m³/h CO and 1 m³/h N2 at roasting temperature of 540 °C. Under the optimized conditions, a magnetic concentrate assaying 61.4 wt% Fe with a recovery rate of 81.8% was obtained from the magnetic preconcentrate of an iron ore tailing. The iron chemical phase, X-ray diffraction (XRD), and optical metallographic microscope analyses revealed that siderite was converted to magnetite successfully after roasting, and some coarse magnetite-hematite interlocking particles were formed due to insufficient reaction time, which could also be recovered by magnetic separation after liberating from gangue minerals. [ABSTRACT FROM AUTHOR]

The iron ore tailing (IOT) is an industrial waste, in which large accumulations represent a serious environmental threat. To reduce the environmental burden and improve the economic benefits, the science and industry focus on the transformation of IOT into new functional materials. In this study, the zeolite A was synthesized from IOT without acid leaching purification. The IOT and zeolite A were studied by XRD, XRF, XPS, SEM, and simply BET. As a result of the hydrothermal reaction, zeolite A was synthesized from the IOT. It was shown that the experimental conditions (SiO2/Al2O3, Na2O/SiO2, and H2O/Na2O) have a significant influence on the type of zeolite and its content in the synthetic products. The calcium ion-exchange capacity and the BET surface area of zeolite A product closely similar to that of the commercial 4A zeolite and superior to the zeolite A synthesized by traditional method discussed in this paper. The research result indicates that the zeolite A can be prepared from IOT and it can be reduce calcium ion as water softener. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a novel method to recover iron from iron ore tailing (IOT) was studied. The method was induced with carbothermic reduction, followed by magnetic flocculation separation (MFS) and conventional magnetic separation (CMS). The effects of reduction temperature, as well as the amount of coal and sodium carbonate on iron recovery efficiency, were chiefly introduced according to the experimental mechanism. Results of carbothermic reduction showed that iron minerals in the IOT were transformed to metallic iron at the reduction temperature of 1100 °C for 120 min, with a C/Ore mass ratio of 25% and a mass ratio of Na2CO3 to ore of 8%. The reduction activity of FeO increased and a deep reduction from FeO to metallic iron was observed with the addition of Na2CO3. The metallization mean of induced reduction ores reached 32.53%. Results of magnetic separation showed that the MFS concentrate grade was 74.02% Fe, with the recovery rate at 79.51% when the reduced samples were ground to 87.4% below 38 μm. This iron recovery increased by 4.19% compared with that of CMS, whereas the iron concentrate grade slightly changed. In addition, the microstructure and phase transformation of the carbothermic reduction process were studied by X-ray powder diffraction, scanning electron microscope, and energy-disperse spectroscopy, thereby complying with the main force analysis of magnetic flocculation in the MFS to help understand the mechanism of the novel method.Graphical Abstract: [ABSTRACT FROM AUTHOR]

The ability of colonizer organisms to tolerate high metal concentrations is important to the restoration and rehabilitation of mining sites. We investigated colonization on modular cellular surfaces-artificial construction-niche-prepared by combining different proportions of iron mine tailings (8% tailing dam material), soil (90%), and cement (2%) through bioassays conducted under stable laboratory conditions of humidity, temperature, and light intensity. The establishment of microorganisms was measured using CO-respirometry and microbiological assays. Sub-aerial communities grown on the experimental materials were composed of heterotrophic and phototrophic macro- and microorganisms. Four groups of phototrophic species were observed: cyanobacteria, algae, mosses, and ferns. The cyanobacteria comprised three genera: Phormidium sp., with branched filaments, Nostoc sp. and Pseudanabaena sp.; algae included Trentepohlia sp. (Chlorophyceae), a sub-aerial or terrestrial green algae. Macroscopic fungal hyphae were also observed. CO production occurred in all cellular modules due to the growth of bacteria, actinobacteria, and fungi. The presence of living organisms on these artificial construction-niche containing iron ore tailings was a promising finding as those colonizers could initiate the processes of primary succession and occupy significant portions of the sub-aerial surfaces, thus actively participating in weathering and soil formation to create new ecological niches for recuperating ironstone outcrop ecosystems. [ABSTRACT FROM AUTHOR]

• The diamond-indent feature of MSF provides favorable interfacial bond strength. • MSF can compensate for the reduction in compressive strength caused by IOTs. • The fracture energy of IOT concrete increases by up to 20.19-fold due to MSF. • The relationship between the FRI and post-cracking behavior is developed. Iron ore tailing (IOT) is a hazardous by-product of iron extraction, and its disposal has resulted in serious environmental issues. This paper investigated the interfacial bond performance of macro-synthetic fiber (MSF). The effect of the IOT replacement ratio on the compressive performance of concrete and the effects of MSF on the compressive and flexural performance of IOT concrete were evaluated. Test parameters included IOT replacement ratio (0%, 50% and 100%), fiber volume fraction (0%, 0.5%, 1.0%, 1.5% and 2%) and fiber aspect ratio (43, 60 and 69). The test results indicated that the deterioration in compressive strength was observed with the increase in the IOT replacement ratio. The mechanism of the effect of IOT on the compressive performance of concrete was analyzed. However, the incorporation of MSF compensated for the reduction in compressive strength caused by iron ore tailings (IOTs). Furthermore, the post-cracking performance, which includes residual flexural tensile strength, equivalent flexural tensile strength and fracture energy, of concrete increased with the increase in fiber volume fraction. The fracture energy of IOT concrete increased by a factor of 18.06–20.19, and the post-cracking performance of IOT concrete was comparable with that of natural sand (NS) concrete at an MSF fiber volume fraction of 2%. At a given fiber volume fraction, the MSF with a higher fiber aspect ratio was more effective in improving post-cracking performance than one with a lower aspect ratio. Moreover, new empirical equations were proposed, which can accurately predict the residual flexural tensile strengths and equivalent flexural tensile strengths. These results provide important implications for determining the contribution of MSF in strengthening and toughening IOT concrete. [ABSTRACT FROM AUTHOR]

This work aims to verify the feasibility of utilizing iron ore tailing (IOT) in porous geopolymer and intends to broaden the application of porous geopolymer in heavy metal removal aspect. Porous geopolymer was prepared using fly ash as resource material, which was partially replaced by IOT at level of 30%, by weight, with H 2 O 2 as foaming agent and removal efficiency, adsorption affecting factors, adsorption isotherms and thermodynamics of Cu 2+ by the developed porous geopolymer were investigated. The experimental results uncover that the porous amorphous geopolymer was successful synthesized with total porosity of 74.6%. The transformation of fly ash and IOT into foaming geopolymer leads to the formation of porous structure encouraging Cu 2+ sorption. Batch sorption tests were carried out and geopolymer dosage, Cu 2+ initial concentration, pH, contact time and temperature were the main concern. Both Langmuir and Freundlich models could explain the adsorption of Cu 2+ on the porous geopolymer due to the high fitting coefficients. The uptake capacity reaches the highest value of 113.41 mg/g at 40 °C with pH value of 6.0. The thermodynamic parameters ΔHº, ΔSº and ΔGº suggests the spontaneous nature of Cu 2+ adsorption on porous geopolymer and the endothermic behavior of sorption process. [ABSTRACT FROM AUTHOR]

Raw powder of iron ore tailing, the catalyst prepared by impregnation approach and the modified catalyst loaded Ag + were investigated for catalytic oxidation of formaldehyde. Prepared materials were characterized by XRD, XRF and BET surface area. Experiments of catalytic activity were carried out in an electrically heated fixed-bed reactor in which 1.0 g of catalyst mixed fully with 10 g quartz sand was added. 200 ppm of formaldehyde gas was introduced into the reactor at a space velocity of 30,000 ml/g·h. Effects of reaction temperature and calcination temperature were considered. The results show that formaldehyde catalytic efficiencies of all materials increase with the increase of reaction temperature. Furthermore, the catalytic efficiency was enhanced when Ag + loaded on the support. Physical properties of raw powder are unsatisfied, but 67% of formaldehyde catalytic efficiency was obtained at the reaction temperature of 100 °C which is far higher than that of other prepared catalysts. [ABSTRACT FROM AUTHOR]

This study aims to broaden the application of iron ore tailing (IOT) in geopolymer. Fresh properties, residual strength, mass loss and microstructure evolution of geopolymer prepared by using fly ash as starting material blended with IOT and activated by sodium silicate and sodium hydroxide solutions were investigated after exposure to 3 and 7 heat-cooling thermal cycles at different target heating temperatures of 200 °C, 400 °C and 800 °C when fly ash was partially replaced by IOT at levels ranging from 0% to 30% with an interval of 10%, by weight. The experimental results uncover that IOT addition influences the workability and setting time of geopolymer especially when more than 20% of IOT is added. Under the effects of thermal cycles, the compressive strength decreases significantly especially after 7 thermal cycles. The loss in compressive strength increases as the cycle target temperature increases from 200 °C to 800 °C. The presence of IOT evidently improves the thermal resistance of geopolymer with the replacement level of IOT less than 30%. The reduced Ca(OH) 2 and the associated formation of additional C-S-H evidences the role of IOT in the formation of C-S-H and supports the results of the increasing compressive strength. Replacing of fly ash with 20% IOT leads to a reduction of the porosity and microcrackings which results in much denser microstructure. Surface Vickers-hardness of geopolymer has also been optimized by IOT addition regardless of exposure target temperature. [ABSTRACT FROM AUTHOR]

An effective method based on iron ore tailing Fenton-like process was studied for removing an azo dye, Acid Orange 7 (AO7) in aqueous solution. Five tailings were characterized by X-ray fluorescence spectroscope (XFS), Brunner−Emmet−Teller (BET) measurement, and Scanning Electron Microscope (SEM). The result of XFS showed that Fe, Si and Ca were the most abundant elements and some toxic heavy metals were also present in the studied tailings. The result of BET analysis indicated that the studied tailings had very low surface areas (0.64–5.68 m 2 g −1 ). The degradation efficiencies of AO7 were positively correlated with the content of iron oxide and cupric oxide, and not related with the BET surface area of the tailings. The co-existing metal elements, particularly Cu, might accelerate the heterogeneous Fenton-like reaction. The effects of other parameters on heterogeneous Fenton-like degradation of AO7 by a converter slag iron tailing (tailing E) which contains highest iron oxide were also investigated. The tailing could be reused 10 times without significant decrease of the catalytic capacity. Very low amount of iron species and almost undetectable toxic elements were leached in the catalytic degradation of AO7 by the tailing E. The reaction products were identified by gas chromatography-mass spectrometry and a possible pathway of AO7 degradation was proposed. This study not only provides an effective method for removing azo dyes in polluted water by employing waste tailings as Fenton-like catalysts, but also uses waste tailings as the secondary resource. [ABSTRACT FROM AUTHOR]

In this paper, a facile synthesis route to obtain mesoporous MCM-41 silica using cetyltrimethyl ammonium bromide (CTAB) as template and iron ore tailing as raw material was reported. The effects of various synthesis conditions on the mesostructure properties of MCM-41, including the molar ratio of CTAB to SiO 2 , gelation pH, aging temperature, aging time and calcination temperature, were investigated in detail. Powder X-ray diffraction (XRD), N 2 adsorption–desorption isotherms, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques had been employed to characterize the samples. The molar ratio of CTAB to SiO 2 and the gelation pH play an important role in the synthesis of ordered MCM-41 mesoporous material structure. The synthesized MCM-41 mesoporous material possessed a BET surface area of 882 m 2 /g, a pore size of 4.2 nm and a pore volume of 1.019 cm 3 /g in the condition of CTAB to SiO 2 in a molar ratio of 0.10:1, pH of 10, crystallization temperature of 100 °C, crystallization time of 48 h and calcination at 550 °C for 3 h. All the results demonstrated the feasibility of employing iron ore tailing as silicon source to produce MCM-41 and provided a new way to convert a solid waste to a value-added material, which has the potential application in the large-scale production of MCM-41. [ABSTRACT FROM AUTHOR]

Ti-MCM-41 were synthesised by one-step method using sodium silicate extracted from iron ore tailing as silicon source, tetrabutyl titanate as titanium source and cetyltrimethylammonium bromide as the template. The effects of various experimental parameters, such as molar ratio of Si/Ti, reaction temperature and time, were investigated. The as-synthesised samples were further characterised by X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron micrographs, N2 absorption-desorption and transmission electron microscopy techniques. The results indicated that Ti-MCM-41 materials possessed the ordered hexagonal mesostructure and high surface area. [ABSTRACT FROM AUTHOR]

• Both mechanical and mechanochemical activation methods are effective to improve the chemical activity of iron ore tailings. • Less surface binding energy reflects less crystallinity and higher reactivity. • Ternary IOTs-based SCMs resulted in the comressive strength enhancement and pore structure refinement. The increasing concern for decarbonization calls for sustainable construction materials since carbon dioxide emissions from cement industries account for 8% of the total emissions. Incorporating municipal solid waste into concrete as supplementary cementitious materials (SCMs) is one of the fundamental ways to achieve urban sustainability. Iron ore tailings (IOTs), a type of mining waste from the beneficiation process of iron ore concentrates, can be used as SCMs via various activation methods. While activation of IOTs alone has been a topic of intensive research for years, there is a lack of comprehensive study on mechanical-chemical coupling activation of IOT-based ternary SCMs systems (IOT, fly ash, and ground granulated blast furnace slag) considering the utilization of other industrial by-products and waste. This study investigates the effect of grinding time and chemical activators on the properties of IOT-based ternary SCMs. XRD, XPS, DTA-TG, compression tests, Mercury intrusion porosimetry, and SEM were employed to investigate the crystal structure and crystallinity of IOTs, surface energy, mechanical properties, pore structure, and morphology of the hydration products of the ternary system. The results obtained from this study revealed that an increase in grinding time and chemical activators improved the activity index of IOTs-based ternary SCMs. In addition, Na 2 SiO 3 contributed the most to the activity index among the three types of activators. This work has expanded the possibility of utilizing IOT-based ternary SCMs via proper activation methods for sustainable construction. [ABSTRACT FROM AUTHOR]

In order to develop the applications of ore tailings, the glass ceramics were prepared by using a conventional melting-quenching-sintering process. The phase component, microstructures, magnetic properties and thermal conductivities of the prepared glass ceramics were investigated by using X-ray diffractometer, scanning electron microscopy, vibrating sample magnetometer and thermophysical properties tester, respectively. The results show that orthorhombic olivine-type phase and triclinic sunstone-type phase formed when the glass was annealed at 700 °C, the concentration of olivine-type and sunstone-type phases decreased, the spinel-type cubic phase occurred and the amount increased when the annealing temperatures increased. The magnetic properties from the cubic spinel ferrites were detected in the glass ceramics, and the related saturation magnetization increased with the annealing temperature increasing. The porous glass ceramics with magnetic property showed much lower thermal conductivity, compared with the non-magnetic porous glass-ceramic and the dense glass-ceramics. [ABSTRACT FROM AUTHOR]