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Density variations of nucleated and non-nucleated samples, treated for 5 min at 730, 750 and 770 1 C.
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Hazardous electro-furnace slag (EFS), dust (D) and converter slag (CS) from ferronickel smelting plant were mixed with glass cullet and vitrified. The optimal heat-treatment regime for transformation of obtained glass into glass-ceramic was evaluated using fast alternative methods: the nucleation step was estimated by DTA analysis, while the crysta...
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Context 1
... density variations of nucleated and non-nucleated samples, treated for 5 min at different temperatures, are shown in Fig. 7. The results confirm that Δρ deviations are inferior in non-nucleated samples and elucidate that the increasing of temperature with 20-40 1C significantly raises the crystallization rate. In fact, at 750 and 770 1C the maximum densities for the nucleated samples are reached after 30-40 and 5-10 min, respectively. These highest values, ...
Context 2
... rate. In fact, at 750 and 770 1C the maximum densities for the nucleated samples are reached after 30-40 and 5-10 min, respectively. These highest values, together with the maximum reached density (nucleated sample after 2 h at Fig. 2. ΔT as a function of the nucleation temperature at holding time of 1 h. 730 1C) also are plotted in Fig. 7 and demonstrate that the obtainable percentage of formed crystal phase decreases with the increasing of temperature. This result is typical for the investigated system [11,15,31] and can be explained with a decreasing of the precipitation with temperature. It can be concluded that the optimal crystallization temperature is at about 750 ...
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Citations
... The chemical and phase composition of the slag (or tailing) have obvious differences between these smelting methods. The ferronickel slag produced by RKEF process is mainly composed of MgO and SiO 2 , which can be recycled and used in the production of cement [15,16], concrete [17,18], refractory materials [13,14], glass ceramics [19,20], geopolymers [21], etc. CaO and Al 2 O 3 are rich in the ferronickel slag produced by BF process, this type of slag can also be used for production of cement [4], concrete [22], and cementitious material [23][24][25], etc. However, high amounts of sodium and sulfur are remained in the tailing in the direct reduction process with sodium sulfate as an additive. ...
During the reductive roasting of laterite ore with sodium sulfate as additive, sodium magnesium silicate and troilite are generated, this leads to high consumption of alkali and in turn environmental pollution of an alkali-rich tailing. Aiming to achieve the sustainable metallurgy by this route, oxygen pressure nitric acid leaching of laterite ore tailing was performed to recycle alkali and then heat storage material was prepared from the leached residue. The laterite ore tailing mainly consists of forsterite (Mg2SiO4), sodium magnesium silicate (Na2Mg2Si2O7), and troilite (FeS), of which 91.45% Na and 83.53% S were leached under the optimal conditions of leaching temperature of 150 °C and time of 60 min, HNO3 concentration of 0.16 mol L−1, and oxygen partial pressure of 0.50 MPa. The alkali can be reclaimed from the leachate after magnesium precipitation followed by evaporation and crystallization. A heat storage material with heat storage density of 243 kJ kg−1 can be prepared from the leached residue. A route for the value-added utilization of this alkali-rich tailing was established.
... Recently, considering the physicochemical features of ferronickel slag, particularly the close mass ratio of magnesia to silica (m(MgO)/m (SiO 2 )) to that in forsterite (Mg 2 SiO 4 ), the authors' group proposed novel strategies to convert ferronickel slag into forsterite refractory materials with high refractoriness of 1730-1840 ºC by conventional and microwave sintering of low-iron ferronickel slag (7.29 wt% FeO) with the addition of 20-25 wt% sintered magnesia at 1350 ºC, respectively [13,[22][23][24][25][26]. Compared to other similar products prepared from ferronickel slag [7][8][9][27][28][29][30], the refractory materials exhibited higher added value ($1100-1300/t) and a larger utilization percentage of ferronickel slag (20-60% vs. 75-80%) [13,[22][23][24][25][26], showing a broad application prospect. However, the feasibility of applying this method for other types of ferronickel slag, such as high-iron EFFS (FeO > 10 wt%) and high-calcium BFFS, has not been reported yet. ...
The feasibility of converting high-iron electric furnace ferronickel slag (EFFS) and high-calcium blast furnace ferronickel slag (BFFS) to refractory materials was assessed by sintering with the addition of low-cost sintered magnesia. The preparation and properties of the refractory materials were investigated and compared based on both thermodynamic and experimental analyses. It was shown that the addition of sintered magnesia could restrain the negative effects of high contents of FeO and CaO in EFFS and BFFS, respectively, with low mass ratios of magnesia to silica (m(MgO)/m(SiO2)), by suppressing the formations of the phases with low melting points, including enstatite, liquid phase, monticellite, and merwinite. Compared to that prepared from BFFS, the refractory material derived from EFFS with higher refractoriness (1663 ºC vs. 1700 ºC), lower bulk density (2.92 g/cm³ vs. 2.70 g/cm³), and larger compressive strength (110.2 MPa vs. 158.5 MPa) was obtained by sintering at 1350 ºC for 3 h with a smaller addition of sintered magnesia (45 wt% vs. 30 wt%). This study proved the possibility of turning different types of ferronickel slag into refractory materials, realizing overall and value-added utilization of the waste.
... This characteristic gives the advantage that glass or GC can be formed at high temperature with little to no addition of additional glassforming precursors (Table 1). Research on glass fibers [Ma et al., 2018, Scarinci et al., 2000 and GCs [Karamanov et al., 2017, Ljatifi et al., 2015, Rawlings et al., 2006 by vitrification of waste are underway to find the viability, through lower cost and good physicalchemical properties, which will enable commercial applications. Asbestos vitrification, for instance, is now a powerful process to destroy the asbestos fiber structure, transforming it into an asbestos-free and vitrified end product [Spasiano and Pirozzi, 2017]. ...
In this review, we provide a perspective on the science and technology of vitrification of waste. First, we provide a background on the general classes of wastes for which vitrification is currently used for immobilization or is proposed, including nuclear and industrial hazardous wastes. Next, we summarize the issues surrounding solubility of waste ions and resulting uncontrolled crystallization or phase separation. Some newer waste form designs propose a controlled crystallization, resulting in a glass-ceramic. A summary of glass systems and glass-ceramic systems is given, with the focus on immobilizing waste components at high waste loading. Throughout, design and processing considerations are given, and the difference between uncontrolled undesirable and controlled desirable crystallization is offered.
... In the field of glass ceramics, using ferromanganese slag to prepare architectural glass ceramics is rarely studied. This is because, compared with other slags, the ferromanganese slag cannot be used at such a high content in traditional CMAS systems [16][17][18]. In traditional CMAS glass ceramics, the CaO content is generally not higher than 20 wt % for the sake of diopside crystallization [19,20]. ...
... However, a specific existing forms of the Q n structures in the high-calcium CMAS systems was still unclear. As NMR is a technique commonly used for short-range and medium-range structure analysis of glass, including 29 Si, 27 Al, 17 O, the study was further carried out by NMR. The relative contents of each silicon-oxygen tetrahedral structure could be obtained by fitting and analyzing the measured curve [29,30]. ...
... the Q n structures in the high-calcium CMAS systems was still unclear. As NMR is a technique commonly used for short-range and medium-range structure analysis of glass, including 29 Si, 27 Al, 17 O, the study was further carried out by NMR. The relative contents of each silicon-oxygen tetrahedral structure could be obtained by fitting and analyzing the measured curve [29,30]. ...
In this work, more than 70 wt % of ferromanganese slag (containing 40 wt % CaO) was used to synthesize high-calcium, CaO-MgO-Al2O3-SiO2 (CMAS) glass ceramics. The effect of SiO2/CaO on the structure, crystallization behavior and microstructure of high-calcium, CMAS, slag glass ceramics was studied by IR, NMR, DSC, XRD and SEM. The results showed that in the high-calcium, CMAS glass ceramics, the main existing forms of silicon–oxygen tetrahedra (Qn) were Q0 and Q1. With the increase in the SiO2/CaO, Qn changed from Q0 and Q1 (main units) to Q1 (main units) and Q2, and then to Q1 and Q2 (main units). The polymerization degree of Qn changed from low to high, making the glass more stable, which led to the increase in crystallization temperature and the decrease in crystallization kinetic constant (k) and frequency factor (υ). At the same time, the change in the Qn structure resulted in a gradual change to the main crystal, from akermanite to diopside–wollastonite.
... Over the past few decades, efforts have been made in the utilization of ferronickel slag. Most have focused on applying ferronickel slag for making construction and building materials (e.g., cement, concrete, and geopolymers) because of the high contents of amorphous SiO 2 [5][6][7][8][9], producing glass ceramics [10,11] and mineral wool [12] due to the glass and X-ray powder diffraction (XRD) in combination with the Rietveld method was used to determine the phases in the FNS. The BGMN program was applied for Rietveld refinement [33]. ...
This paper provides a technical approach for efficiently recovering Mg from ferronickel slag to produce high-quality magnesium oxide (MgO) by using the sulfuric acid leaching method under atmospheric pressure. The leaching rate of magnesium is 84.97% after a typical one-step acid leaching process, which is because Mg in FNS mainly exists in the forsterite (Mg2SiO4) phase, which is chemically stable. In order to increase the leaching rate, a two-step acid leaching process was proposed in this work, and the overall leaching rate reached up to 95.82% under optimized conditions. The response surface methodology analysis for parameter optimization and Mg leaching rules revealed that temperature was the most critical factor affecting the Mg leaching rate when the sulfuric acid concentration was higher than 2 mol/L, followed by acid leaching time. Furthermore, interactive behavior also existed between the leaching temperature and leaching time. The leaching kinetics of magnesium from FNS followed a shrinkage-nuclear-reaction model with composite control, which were chemically controlled at lower temperatures and diffusion controlled at higher temperatures; the corresponding apparent activation energy was 19.57 kJ/mol. The leachate can be used to obtain spherical-like alkali magnesium carbonate particles with diameters of 5–10 μm at 97.62% purity. By using a further calcination process, the basic magnesium carbonate can be converted into a light magnesium oxide powder with a particle size of 2–5 μm (MgO content 94.85%), which can fulfill first-level quality standards for industrial magnesium oxide in China.
... Apart from BFS, SS, and SSS, there is growing interest in reusing other types of slags for production of glass-ceramics, including EFFS (Ljatifi et al., 2015), CS Yang et al., 2014b), FS , and LFS , as summarized in Table 1. ...
... In China, the annual production of EFFS exceeds 30 million tons, and it has become the fourth largest metallurgical waste after BFS, SS and red mud (Gu et al., 2019a,b). For utilization of the slag, Ljatifi et al. (2015) prepared parent glasses by melting of 56 wt % EFFS, 30 wt % glass cullet, 7 wt % rotary kiln filter dust, and 7 wt % converter slag (Table 1). After two-stage heat treatment, consisting of nucleation (650 • C) and crystallization (750 • C), the mono-phase pyroxene-based glass-ceramics with crystallinity of about 50% was obtained. ...
The CaO–MgO–Al2O3–SiO2 (CMAS) glass-ceramics are a new type of building decoration materials, which can be prepared using silicate-bearing metallurgical slags as raw materials for both economic and environmental benefits. This study offered a systematic review of preparation of CMAS glass-ceramics from various metallurgical slags based on analyses of characteristics, preparation methods of slag-based glass-ceramics, and the influence of heat treatment, chemical components and nucleating agents on the phase composition, microstructure and properties of glass-ceramics. It was found that a large number of metallurgical slags, including blast furnace slag (BFS), steel slag (SS), stainless-steel slag (SSS), electric furnace ferronickel slag (EFFS), copper slag (CS), ferromanganese slag (FS) and lead fuming slag (LFS), have the potential to serve as the main raw materials for producing CMAS glass-ceramics because of their chemical composition similarities to the products. However, the minor or residual elements, such as chromium, in the slags may directly affect the properties of the glass-ceramics mainly because of their impacts on the nucleation and crystallization in parent glasses which are in need of control. Special attention of this review was devoted to the challenges from the aspects of cost, safety and diversification in preparing the glass-ceramics from metallurgical slags and to corresponding solutions for maximizing utilization of the wastes with desirable product quality.
... Therefore, how to efficiently use MgO and FeO in the FNS is one of the key issues for preparing glass-ceramics from FNS. By now, few studies have been focused on the preparation of glass-ceramics from FNS. Ljatifi et al. synthesized mono-phase pyroxene based glass-ceramics from the mixture of 56 wt % FNS, 30 wt % glass cullet and other waste [17]. The results showed that the product density increased with temperature and time. ...
... The above results showed that a good enstatite-spinel based glassceramic with excellent properties, namely density of 3.11 g/cm 3 , bending strength of 116 MPa, acid resistance of 99.97%, and alkali resistance of 99.70% could be obtained by controlling crystallization of the melted mixture of 75 wt % FNS and 25 wt % CFA at 867 • C for 2 h. With a much higher utilization percentage of FNS (75 wt % vs. 58 wt %), the product had properties comparable to those derived from similar wastes, such as the mixture of FNS, filter dust, container glass and converter slag, reported in literature [17,18]. These properties were also superior to those required by the Chinese Industry Standard of Glass-Ceramics Plate for Industrial Application (JC/T 2097-2011) and the Chinese Industry Standard of Glass-Ceramics for Building Decoration (JC/T 827-2019). ...
In this study, a new approach was proposed to prepare high-quality enstatite-spinel based glass-ceramics from the mixture of ferronickel slag (FNS) and coal fly ash (CFA) by examining the effect of CFA content on the preparation process based on both thermodynamic and experimental analyses. The thermodynamic exploration indicated that choosing enstatite as the main crystal phase in the target glass-ceramics along with spinel was suitable for co-utilization of both wastes. The experimental analysis showed that the crystallization temperature of parent glass, an intermediate product prepared from the mixture, increased from 864 °C to 907 °C as the content of CFA increased from 20 wt % to 35 wt %. Conversely, the depolymerization degree of the glass presented a decreasing trend, implying the denser glass structure which could promote chemical stability of the product. After crystallization of the parent glass, the main phase in the resulting glass-ceramic sample was transformed from enstatite (MgSiO3) to aluminum enstatite (Mg0.96Al0.027SiO3). There were simultaneous microstructural transitions from a spherical structure through a blocky structure to a plate prismatic structure, lowering bending strength of the product. By controlling crystallization of the melted mixture of 75 wt % FNS and 25 wt % CFA at 867 °C for 2 h, the resulting enstatite-spinel based glass-ceramic obtained excellent properties, namely density of 3.11 g/cm³, bending strength of 116 MPa, acid resistance of 99.97%, and alkali resistance of 99.70%. With a much higher utilization percentage of FNS, the product had properties comparable to those derived from similar wastes reported in literature. This study provides an efficient method for co-utilization of FNS and CFA.
... At this temperature, however, some certain smoothing of the shape is observed and after that, initiates the beginning of the foaming process. Further, Figure 1c corresponds to material formation characterized with smooth auto-glazed surface due to the fact that this temperature is slightly above the HSM softening point [21,22]. ...
The materials used for the synthesis of parent glass are 70% wt. metallurgical slag and 30% wt. industrial quartz sand. The initial batch is melted at and then quenched in water. The resulting glass frit is milled bellow 75 microns and pressed 1400 °C into “green” samples. In a next stage, they are heat treated at different temperatures with various heating rates and holding times. As a result, it is demonstrated the possibility for production variations, allowing the manufacture of three types of new materials by using the same pressed glass powders. We highlight the flexibility of the synthesis obtaining namely well densified glass-ceramics at about 950 °C, self-glazed glass-ceramics at about 1000 °C or glass-ceramic foams at approximately 1100 °C. The first set of materials is characterized by very well sintered structure combined with reasonable crystallinity; the second one—by smooth self-glazed surface with an attractive appearance and good properties and the third one—by 80–90% closed porosity and very good thermal stability above 1000 °C.
... For utilization of ferronickel slag, making construction and building materials (eg, cement and concrete), [10][11][12] producing geopolymers 13,14 and glass ceramics, 15,16 and recovering metals (eg, Ni and Co) 17,18 from the slag have attracted huge attention. However, those methods have a few drawbacks, causing inefficient utilization of the slag. ...
The study provides a method for improving the quality of the refractory material prepared from ferronickel slag by promoting the spinel formation and growth in the slag which was sintered with sintered magnesia and chromium oxide in a broad sintering temperature range from 1200°C to 1500°C. According to the thermodynamic analysis, except for forsterite due to the addition of sintered magnesia, a number of high‐melting point spinel phases can also be formed in the presence of chromium oxide and this trend becomes more apparent with increasing sintering temperature, along with declined presence of low‐melting point clinopyroxene, mainly enstatite. This expectation was verified by conversion of a part of the original phase of ferronickel slag, olivine, to two main spinel phases, including magnesium aluminate spinel and donathite which was produced by the replacement of nontoxic Cr3+ ions with Fe3+ ions in the octahedral vacancies of magnesium chromate spinel. The formation and growth of these spinel phases were promoted by elevating temperature from 1200°C to 1500°C, which accelerated the transition of initially generated enstatite to a glassy phase, in favor of densification. The formation and growth of spinel during sintering contributed to high refractoriness and compressive strength of the resulting refractory materials Fabrication of refractory materials from ferronickel slag by sintering was explored in a broad temperature range. Increasing sintering temperature promoted the formations of forsterite and spinel. The spinel particle size increased rapidly with increasing sintering temperature.
... Similarly, other studies have also demonstrated that CWG, coupled with other materials and at optimal conditions, could potentially be used in the manufacture of glass-ceramics. 133,[159][160][161][162][163][164] Toniolo et al 165 evaluated the potential of using CWG (soda lime) in fly ash-based geopolymers by conducting mechanical, microstructural, and leaching experiments. The ceramic mixture was prepared using aqueous NaOH solutions as alkali activation, while a liquid to solid ratio of 0.45 was set to achieve good workability. ...
Each year, hundreds of thousands of tonnes of industrial wastes are being stockpiled, landfilled and disposed of in storages occupying large areas of land that would otherwise be available for productive use. Recycling of such wastes is now becoming of urgent global interest due to increasing population, the rise in anthropogenic activities, and the need for more efficient resource and waste management systems. Among many wastes, the generation of glass is dramatically increasing, particularly in the municipal, industrial and construction sectors. In civil engineering, in general, crushed waste glass has been mainly investigated as a substitute for sand and fine‐grained aggregate in concrete production. In geotechnical engineering, in particular, the application of glass wastes are mainly limited to road pavements or as an additive to different soils for subgrade improvement. While glass wastes are relatively inert and potentially offer several opportunities for recycling as a substitute for diminishing and increasingly expensive sand supplies, their potential use yet remains relatively under‐researched. This paper systematically reviews the current status of knowledge on the use of glass wastes in various civil engineering applications and discusses the suitability assessment of waste glass for use as a sustainable alternative to traditional civil engineering materials.
