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Polyethylene terephthalate (PET) fabric materials are broadly applied in daily life. However, on one hand, they suffer problem of easy contamination by dust owing to their hydrophilicity, which largely reduce their lifetime. On the other hand, their inflammability will bring many potential safety hazards. Therefore, in this paper, PET fabric material with superior superhydrophobicity and flame retardance through a fluorine-free layer-by-layer (LBL) method was developed, which effectively extended its lifetime and range of applications. The LBL technique was realized through assembly of the mixed polyelectrolytes include chitosan (CS), phytic acid (PA), and ammonium polyphosphate (APP) for only two bilayers (BL), which endowed the fabric superior fire retardance. A final layer consisted of steel slag (SS) particles and octadecylamine (ODA) were further assembled onto the flame-retardant fabric, which successfully gave rise to superior superhydrophobicity with water contact angle (WCA) of 155° and water sliding angle (WSA) of 2°. Compared with the pure fabric, the limited oxygen index (LOI) values of the coated fabric were enhanced from 19.8% to 29.2%. The finally obtained fabric also showed excellent self-cleaning and anti-fouling capabilities. It could be used to highly efficiently separate various oil–water mixtures. It also could endure long-time heating treatment at high temperature of 180 °C without affecting the superhydrophobicity and flame retardance. This method was fluorine-free and made good use of waste SS particles. Such fabric was believed to find vary promising applications in water repellence, self-cleaning, flame retardance, anti-fouling, and liquid separation fields.

Corrosion is regarded as one of great challenges for the application of salts-based phase change materials. To address such problem, a novel skeleton of modified diatomite-based porous ceramic was used to load NaNO3 salt and develop shape-stabilized NaNO3. Particularly, thermophysical properties of composites with skeletons of unmodified and modified diatomite-based porous ceramics (UM-DC and M-DC4) were analyzed. The results showed that these two skeletons effectively prevented NaNO3 from leakage and were chemically compatible with NaNO3. Shape-stabilization of NaNO3 using porous ceramic hardly changed phase transition temperature, but decreased latent heat and enhanced thermal stability. M-DC4 possessed a capacity to load 58.67 wt% salt, nearly 10 wt% higher than other porous ceramics. Compared with NaNO3/UM-DC, NaNO3/M-DC4 performed a higher thermal energy storage density and efficiency of 382.92 J/g and 58.71%, respectively, within 130–330 °C. Importantly, NaNO3/M-DC4 exhibited much better cycling stability during 500 thermal cycles, benefited by the improved micro-flow of molten salt in M-DC4; while NaNO3/UM-DC appeared crack after 100 thermal cycles. Accordingly, the novel skeleton could greatly enhance thermophysical properties of shape-stabilized NaNO3. Such composites could be easily integrated into solar thermal energy storage system. This work proposed a new strategy for the application of salts-based phase change materials.

The applications of salts-based phase change materials (PCMs) are greatly restricted by their corrosion to containers and low thermal conductivity. To address these issues, a modified diatomite-based porous ceramic (MDPC) was prepared to shape-stabilize KNO3 salt in this paper. Particularly, effects of graphite content on the pore structure of diatomite-based porous ceramic (DPC) and MDPC on the thermophysical properties of shape-stabilized KNO3 were investigated. The results showed that 30 wt% graphite increased apparent porosity of DPC up to 67.21% and enlarged average pore diameter from 0.71 to 3.58 μm, while weakened its compressive strength from 19.12 to 5.51 MPa. The MDPC effectively prevented leakage of molten KNO3 to avoid its corrosion problem, and possessed an excellent chemical compatibility with KNO3 salt. Additionally, the MDPC hardly changed phase transition temperature of shape-stabilized KNO3, while increased latent heat of composites from 51.70 to 60.21 J/g due to its higher apparent porosity. The MDPC was also shown to enhance thermal conductivity of shape-stabilized KNO3 from 1.16 to 1.52 W/(m·K) at 25 °C, which was attributed to that the MDPC with a larger pore size was more easily infiltrated by molten salt, contributing to a lower apparent porosity of composites. Compared with pure KNO3, thermal conductivity and thermal stability of shape-stabilized KNO3 were seen to be significantly improved by 238% and 60 °C, respectively. This work therefore solved two key challenges for the application of KNO3 salt, and proposed an effective way to improve thermophysical properties of such heat storage material.

Hydro-sodalites are zeolitic materials with a wide variety of applications. Fly ash is an abundant industrial solid waste, rich in silicon and aluminum, from which hydro-sodalite can be synthesized. However, traditional hydrothermal synthesis methods are complex and cannot produce high-purity products. Therefore, there is a demand for processing routes to obtain high-purity hydro-sodalites. In the present study, high-purity hydro-sodalite (90.2wt%) was prepared from fly ash by applying a hydrothermal method to a submolten salt system. Samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), and Fourier transform infrared spectroscopy (FUR) to confirm and quantify conversion of the raw material into the product phase. Purity of the samples prepared with an H2O/NaOH mass ratio of 1.5 and an H2O/fly ash mass ratio of 10 was calculated and the conversion process of the product phase was studied. Crystallinity of the product was influenced more by the NaOH concentration, less by the H2O/fly ash mass ratio. The main reaction process of the system is that the $${\rm{SiO}}_3^{2-}$$ ions produced by dissolution of the vitreous body in the fly ash and Na+ ions in the solution reacted on the destroyed mullite skeleton to produce hydro-sodalite. This processing route could help mitigate processing difficulties, while producing high-purity hydro-sodalite from fly ash.

High-alumina fly ash microbeads and steel slag were used as main raw materials to synthesize feldspar porous ceramics via high-temperature solid phase sintering by adding pulverized coal as a pore-forming agent. The effects of the steel slag and pore-forming agent on the apparent porosity and flexural strength of porous ceramics were investigated. The phase composition and microstructure of porous ceramics were characterized using X-ray diffraction and scanning electron microscopy, and the results indicated that the added amount of steel slag was only related to the amount of liquid phase formed in porous ceramics. The higher the amount of steel slag added, the more the liquid phase formed. At the same sintering temperature, the higher the pore former content, the higher the porosity of the porous ceramics and the lower the bending strength. When porous ceramics were sintered at 1160 °C steel slag melted and fly ash microsphere structures were formed. When the porous ceramics were sintered at 1190 °C, the fly ash microsphere structure disappeared. After the internal liquid phase of the ceramic was formed, the lower the sintering temperature, the larger the porous ceramic structure factor, the more sensitive the flexural strength to changes in porosity and the higher the theoretical strength of ceramic densification. Moreover, as the sintering temperature decreased, the network structure formed during the reaction of fly ash microbeads with CaO greatly increased the flexural strength of fly ash ceramics. When the sintering temperature, sintering time and pore former content were 1170 °C, 120 min, and 10%, respectively, the obtained porous ceramics presented superior apparent porosity and flexural strength (49.21% and 12.88 MPa, respectively), and the main crystalline phase of porous ceramics was anorthite featuring pore size ranging from 5 to 50 μm.

Ferrochrome slag (FS) and tundish slag (TS) are two typical slags containing high contents of Cr2O3 (3.88 wt.%) and MnO (18.69 wt.%), respectively. In this study, batches of ceramics were prepared from FS and TS, and their Cr/Mn leaching behaviors, mechanical properties and microstructures were investigated. Results showed that ceramics with 80 wt.% FS or 85 wt.% TS had acceptable properties. By controlling its composition and sintering temperature, pyroxene or spinel phases could become the main crystalline phases of the fired ceramics containing either of the two slags. For both slag series, pyroxene phases contributed to higher bending strengths, whereas spinel phases led to lower Cr/Mn leaching rates. Both ceramic containing 20 wt.% FS and ceramic containing 85 wt.% TS had the main crystals of pyroxene phases and possessed the highest bending strengths (FS20: 114.52 MPa and TS85: 124.61 MPa). However, both ceramic containing 80 wt.% FS and ceramic containing 25 wt.% TS with main crystals from the spinel phases had the lowest Cr/Mn leaching rates (FS80: Cr 0.05% and TS25: Mn 0.43%). Therefore, optimum designs for the compositions of ceramics from different slags were achieved by changing the proportions of pyroxene and spinel phases to obtain a balance between the high strengths of materials and the stable retention of heavy metal ions. This study provides an important basis for long-term research on the large-scale reuse of heavy metal-containing slags in the ceramic industry.

Anaerobic digestion is a promising technology for the recovery of energy from waste activated sludge. With the increasing use of ZnO- and TiO2-engineered nanoparticle materials (ENMs) and their accumulation in sludge, their combined effect on anaerobic digestion was investigated. The toxicological mechanism involving Zn2+ bioavailability and reactive oxygen species (ROS: ·OH and H2O2) was initially investigated and confirmed. Results showed that ZnO ENMs inhibited the metabolism of volatile fatty acids (VFAs) and the production of biogas because of Zn2+ and ROS. The metabolic pathway of butyric acid to acetic acid was inhibited. The biogas production in the system 30ZnO and 80ZnO were reduced to 67.4 and 31.5 mL/g VSS, respectively, compared with 86.3 mL/g VSS in the control group. The toxicity of ZnO ENMs on anaerobic digestion was reduced in the presence of TiO2 ENMs because of the reduction of Zn2+ bioavailability. The biogas production 30ZnO+80TiO2 system was 80 mL/g VSS, which approached to the control group. The microbial analysis of a multi-ENM anaerobic digestion system revealed that cell membrane integrity, microbial abundance, and community structure were affected. Zn2+ bioavailability and ROS likely altered microbial communities.

High apparent porosity ceramics have a wide range of applications in chemical, environmental, and automotive sectors as reactors, absorbers, and cleaning devices due to their large specific surface area and excellent permeability for fluids. In this paper, porous ceramics with high apparent porosity were successfully fabricated from diatomite. Importantly, the pore structure of this ceramic was further modified by calcium carbonate (CaCO3). The results showed that the pores of the modified ceramic were in the space between the loose particles, and the position originally occupied by the calcium carbonate. An addition of 0–50 wt% CaCO3 improved the apparent porosity up to 67.53% and enlarged the pore size from ~0.7 to ~26.6 µm due to the decomposition of CaCO3, generating new pores and further transforming isolated pores to interconnected ones. The crystalline phase composition of the ceramic was found to change from cristobalite to the combination of cristobalite, wollastonite and larnite with the addition of CaCO3. The results also showed that an addition of more than 40 wt% of CaCO3 did not give much further increase in the apparent porosity due to the densification process. The modified ceramics were found to have a good mechanical strength; the ceramic with the highest apparent porosity (67.53%) had a compressive strength of 7.33 ± 0.28 MPa.

The sintering mechanism of novel SiO2-Al2O3-CaO-MgO ceramics obtained from red mud was studied using two batches of ceramics mixed with 50 wt% red mud. The sintering behavior and mechanical properties were studied, and crystal evolution was investigated using X-ray diffraction (XRD), especially in situ XRD. Results showed that anorthite with Na+-solidification played the role of flux to reduce the optimal sintering temperature of ceramics by about 50 °C (1080 °C for ceramic sample #2), whereas hematite, residual quartz, and generated pyroxene formed the skeleton phase in ceramics during high temperature sintering. Formation of more pyroxene in ceramics improved the bending strength (115.88 MPa for ceramic sample #1). Slow cooling was beneficial to precipitate more pyroxene and less anorthite during sintering. This research is of special interest for the utilization of red mud in ceramics.

A new swirl combustion device was designed and enhanced, which realized the utilization of steel slag, achieved highly efficient and clean coal combustion, and simultaneously realized a fully elemental utilization of coal. The distribution laws of different sized particulate matter (PM) emission and the enrichment laws of elements in particles under diverse conditions (such as various excess air coefficients and different coal ratios) were systematically studied. The enrichments of PM under both non-staged and fuel-staged conditions were also investigated. The results indicated that fuel-staged combustion is more helpful in reducing PM emissions than non-staged combustion, and a suitable coal ratio is also beneficial for reducing PM emissions. The melted liquid steel slag drop captured the fly ash produced from pulverized combustion, thus reducing PM emission. The alkali metal elements (K, Na, and Mg), the trace elements (As and Ti), and S have an obvious enrichment tendency in PM1 and PM2.5. A different coal ratio under fuel-staged combustion has a significant influence on the enrichment of Al, Si, Ca, and Fe in PM1, whereas in PM2.5, PM4, and PM10, the effect of different coal ratios on the enrichment of each element is slight.

This study investigated the inactivation efficiency of ZnO nanofluids against E. coli in sonophotocatalysis with the aeration of nitrogen, oxygen, argon and their mixtures. The results showed that inactivation efficiency was increased when aeration was combined with sonophotocatalysis. Addition of different types of gases could lead to the different inactivation efficiency. The inactivation efficiencies were shown in the following order: no aeration nitrogen argon oxygen Ar/O

In this work, empirical kinetics, response surface method (RSM) and artificial neural network (ANN) were employed to model and optimize electrochemically activated persulfate process. Electrochemically activated persulfate using a sacrificial iron anode was used as a cost effective method to degrade sulfamethoxazole (SMX) in aqueous solution. The individual and the interactive effects of operation parameters such as pH, applied current, persulfate concentration and electrolysis time were investigated. Eight unseen experiments beyond the experimental design were performed to test the accuracy of the generalization ability of the models. Based on the unseen experiments, ANN demonstrated the superiority in predicting the results when compared to empirical kinetics and RSM modeling. Response surface analysis was used to illustrate the interactions between parameters pH/applied current, pH/persulfate concentration and pH/electrolysis time. Sensitivity analysis indicated that the relative importance of the influencing parameters were of the following order: electrolysis time > pH > applied current > persulfate concentration. The highest degradation efficiency was achieved with the optimal conditions of pH of 3.43, the applied current of 18.4 mA, the persulfate concentration of 3.54 mM, and the electrolysis time of 60 min. The electrical energy consumption was also calculated at this optimized condition (0.04 kWh ⋅ m−1order−1). The work provides a novel predictive and optimized model for SMX removal under different conditions by electrochemically activated persulfate.

Rare earth (RE) and iron minerals in tailings exhibit fine embedded granularity and are closely associated with silicates, carbonates, and other lode minerals, which are difficult to be recycled. Studies of these tailings led to some new processes of ore dressing, involving grinding, RE flotation, strong magnetic separation, and positive iron flotation. In this closed circuit process, RE and iron minerals were separated after grinding, and the materials resulted from the flotation of small-sized RE and iron mineral particles were accurately controlled using a combination of inhibitors, dispersants, pH regulators, and collector agents. The ore dressing were ground to a fineness of 0.045 mm, which was a process accounting for 95.6% of the material. The amount of water glass, NXJ (a combination of sodium carbonate mixed with a fine mud dispersant), and BGH (hydroxamic acid collector, a combination of 3-carboxy-2-naphthylhydroxamic acid and C5-9 hydroxamic acid) used in the primary separation of RE were 2.4 kg/t, 2.5 kg/t, and 2.4 kg/t, respectively. The dosages of ammonium fluorosilicate and GXY (fatty acid collector, a combination of sodium oleate mixed with oxidized paraffin soap) used with iron coarse were 2.2 kg/t and 1.2 kg/t, respectively. The RE collectors achieved chemical separation of Ce, La, and other particles and formed stable five-membered cyclic chelates. Consequently, through the closed circuit experiment, the RE grade and recovery rate in the RE concentrate were improved to 50.3 and 61.6%, respectively. The total iron (TFe) grade and recovery rate in the TFe concentrate were improved to 64.0 and 30.0%, respectively, and other useful metals were also enriched; this process managed secondary recycling of RE and TFe possible, leading to improvements in resource utilization.

A method for preparing novel ceramics was developed in this study. Different ratios red muds were added to steel slags to optimize the preparation of novel ceramics by a traditional ceramic preparation process. The sintering mechanism, microstructure, and performance were studied by X-ray diffraction techniques, scanning electron microscopy, and combined experiments of linear shrinkage, water absorption, and flexural strength. The results confirmed that red mud can reduce the volumetric instabilities through the complementarity of red mud and ferroalloy slag. The crystal phases in the ceramics are all pyroxene group minerals, including diopside ferrian, augite, and diopside. The flexural strength of the ceramic that contains 40wt% red mud and was prepared at the optimal sintering temperature (1140°C) is greater than 93 MPa; its corresponding water absorption is less than 0.05%.

The pilot trial of detoxification of chromium slag in cyclone furnace and production of slag wool fibres were investigated in a power plant in China. 10–30 wt.% chromium slag was mixed with pulverized coal and 0–10 wt.% limestone as the raw materials of the cyclone furnace. Cr(VI) in chromium slag was reduced to Cr2O3 inside the cyclone furnace at high temperature. The melt was then produced into slag wool fibres through high-speed centrifugation. Optimal fibres with shot content of 4.5%, average diameter of 4.8 μm and acidity coefficient of 1.6 were produced with 15 wt.% chromium slag and 5 wt.% limestone in the mixture. Leaching toxicity test showed Cr(VI) of 0.016 mg/L of the produced fibres, which is far below the national standard of China. The total energy consumption could be significantly decreased compared to traditional cupola furnace method. This technique provides an effective and comprehensive technique for the detoxification and utilization of chromium slag at low cost and large-scale.

Porous ceramics with high apparent porosity have wide applications in various fields. In this work, high apparent porosity ceramics were fabricated from fly ash cenosphere. Effects of sintering temperature and CaCO3 on the apparent porosity were investigated. More importantly, the formation mechanism of high apparent porosity was proposed. Results showed that the sintering temperature decreased the apparent porosity in densification process. The addition of CaCO3 improved the apparent porosity in two ways: one was that CO2 emission from CaCO3 decomposition promoted the formation of pores in ceramics; the other one was that CaO from decomposed CaCO3 was transformed into anorthite with fly ash cenosphere, which generated the porous structure of fly ash cenosphere shell. In this work, the apparent porosity of ceramics with 30 wt% CaCO3 sintered at 1250 °C reached 59.25%, and the corresponding compressive strength was 70 ± 2.58 MPa. Results also indicated that the skeleton structure of interconnected fly ash cenosphere guaranteed a relatively high mechanical strength of this porous ceramics.

Utilization of hot slag and its waste heat (1450–1650 °C) constitute a great challenge for iron and steel industry. In recent years, a method different from the traditional one, has been developed to integrate utilization of waste heat and mass of hot slag, which has as an objective to prepare value-added materials and to establish a much cleaner production. During the process, composition and structure of hot slag are modified to meet the need of target materials, while its waste energy is utilized to lower heat consumption during the melting and reactions of raw materials. To carry out such modification process, a novel modifying furnace, which was composed of an upper part, cyclone furnace (CFu) and the bottom part, modifying chamber (MCh), was designed and constructed during this research. Experiments to investigate the effect of different process parameters on temperature distribution in the furnace and preparation of glass-ceramics from the modified hot slag were conducted. Cooled modifiers mainly composed of fly ash were initially heated in CFu and then placed into the molten bath in MCh to mix with hot steelmaking slag. During the modification process, the maximum temperature reached 1500 °C in the mid-bottom part of CFu. An increase of a secondary air stream could decrease the CFu temperature but had no significant impact on the MCh temperature. Input of a primary oxygen-rich air stream could guarantee higher temperature in both the CFu at 1400–1600 °C and the MCh at 1400–1450 °C. The optimum parameter of velocities was (100–120) × 2 m 3 /h for primary air stream, (10–16) × 2 m 3 /h for oxygen gas stream and 315–568 m 3 /h for secondary air stream. To achieve efficient flow ability and take advantage of more hot slag, the steel slag was modified to include a higher basicity (CaO/SiO 2 ) of 0.6–0.7 compared to the traditional product (commonly below 0.5). Glass-ceramics, derived from the water quenched modified slag after heat treatment, was finally prepared with excellent performances.

Incorporating solid waste into cement and concrete products can save natural resources and reduce environmental problems caused by the disposal of industrial solid waste. In this study, steel slag powder and waste glass powder were synergistically used to replace cement. The blended cementitious materials showed good mechanical strength and autoclave stability with the synergistic aid of steel slag and waste glass. This study used an autoclave experiment to accelerate the hydration reaction. Results suggested that waste glass as an amorphous siliceous material enriched hydration products and completely consumed f-CaO in steel slag under autoclave for 3 h. The expansion rate of the blended paste was the lowest, and the stability was the best when the mass ratio of ordinary Portland cement: steel slag powder: waste glass powder was 7:2:1. A complete reaction of f-CaO occurred in the steel slag in the presence of an excess of waste glass powder in the blended cementitious materials. An excessive waste of glass powder can cause alkali–silicon reaction with Na+ and K+ ions and lead to expansion.

Low thermal conductivity and corrosion problem of NaNO3 salt-based phase change materials (PCMs) are regarded as two critical barriers for their applications in thermal energy storage. To address the above problem, a diatomite-based porous ceramic modified by CaCO3 was firstly used to develop shape-stabilized NaNO3 in this work. Particularly, contribution of modified diatomite-based ceramic on improving thermal conductivity of the composite was investigated. Compared with traditional diatomite-based skeleton, diatomite-based ceramic was found to contribute to a 129% higher thermal conductivity of composites, benefited by the generation of a dense and continuous skeleton that consisted of newly formed cristobalite phase with a higher thermal conductivity. While crack occurred on the composite with diatomite-based ceramic after 100 thermal cycles, resulting in the leakage of salt and the decrease of thermal conductivity. By contrast, diatomite-based ceramic modified by no more than 40 wt% CaCO3 effectively avoided the crack of composites, exhibiting quite a stability in shape and thermal conductivity during 500 thermal cycles. The modified ceramic was shown to improve the thermal conductivity of loaded NaNO3 by 118%, up to 1.22 W/(m·K) at 25 °C. The results also indicated that the modified ceramic hardly changed the phase transition temperature of NaNO3, but decreased the latent heat of composites, while possessed a much higher capacity to load salt (57 wt% NaNO3) than that of other porous ceramics. The composite with modified ceramic was demonstrated to have a good cycling stability in thermal properties as well, which performed a considerable potential in thermal energy storage.

As an approach for reusing greater amounts of red mud, which has high CaO and Na 2 O content, batches of novel SiO 2 -Al 2 O 3 -CaO-MgO (10 wt%) ceramics that were mixed with 20 wt%, 35 wt% and 50 wt% red mud were prepared. Na + -leaching and physical properties of these ceramics were tested. Crystal evolution and sintering process were investigated using thermal gravity analysis-differential thermal analysis, X-ray diffraction, and scanning electron microscopy. Results showed that, although Na 2 O content in the ceramics increased from 2.15 wt% to 4.21 wt%, Na + -leaching rates of fired ceramics were almost constant and were about 6 times lower than that of green samples. Main crystal components were diopside ferroan, augite, and anorthite, each of which solidified Na + . Moreover, their solidifying abilities increased with increasing temperature. Of these components, anorthite had the greatest ability to solidify Na + . Ceramics with highest content of red mud (50 wt%) had lowest optimum sintering temperature of 1130 °C, widest sintering range from 1110 to 1140 °C and excellent properties, including a bending strength of 115.88 MPa, water absorption of 0.07%, Na + -leaching rate of 0.33%, and K + -leaching rate of 0.10%. This work provides important basis for long-term work on the reuse of red mud in the ceramics industry.

Aiming at a novel application of biomass, coupled biomass gasification and iron ore reduction was investigated and demonstrated in this work through pyrolysis/gasification of iron ore–lignin pellets (ILP) at 1093–1333 K. The solid, liquid and gaseous products were analyzed by XRD, SEM, chemical analysis, GC-MS, GC and TG-FTIR. Direct reduction iron (DRI) and gaseous products (CO, H2 and CH4) were produced in the process. The metallization degree of the iron ore and CO content of the gaseous products increased with increasing the reaction temperature, as expected. The gas yield from the experiments with ILP was much higher than that from the tests with lignin pellets (LP) at 1173–1333 K, owing mainly to the iron ore reduction producing a larger amount of CO. Whereas, the yields of oil and char in the ILP reduction process were found to be much lower than those from the tests with lignin alone, due to the conversion of oil and char products into gaseous products catalyzed by the iron oxide and metallic iron. Thus, in pyrolysis/gasification of ILP the presence of lignin provided reducing agents for reduction of iron oxide, whereas the presence of iron oxide/metallic iron provided an oxidant/catalyst for biomass gasification.

With the increasing use of engineering nanomaterials (ENMs) in industrial and domestic products, ENMs inevitably enter into wastewater treatment plants and remain in sewage sludge. Most of the reported studies on anaerobic digestion were focused on the impact of ENMs on different types of ENMs, methane production, key metabolism enzymes and microorganisms. Little attention was paid to the effect and mechanism of ENMs on volatile fatty acids (VFAs) accumulation during anaerobic digestion. In this work, the concentration of accumulative VFAs during anaerobic digestion with the presence of ZnO ENMs was found to be affected positively compared to the control (without ZnO ENMs). The enhanced VFAs accumulation in the presence of ZnO ENMs was contributed to slowly production and consumption of VFA during anaerobic digestion. Mechanism exploration suggested that impact on protein hydrolysis and change of archaea community structure were the main reasons. Further investigation revealed that Zn2+ is one of the main reasons for the impact of ZnO ENMs on VFA accumulation in sludge anaerobic digestion.

Inferior clay rich in CaO and Fe 2 O 3 is a typical clay with huge reserves in southwest of China, which cannot be used in traditional aluminosilicate system ceramics. To efficiently utilize the inferior clay, a method of preparing novel ceramics containing CaO and Fe 2 O 3 was put forward. In this study, effects of inferior clay proportion on properties, CaO on evolution of crystalline phases and Fe 2 O 3 on densification process were analyzed by XRF, XRD, TG-DTA and SEM-EDS combined with physical properties tests. The results showed that addition of inferior clay (from 20 to 70 wt%) significantly affected sintering temperature (from 1190 to 1130 °C). High activity CaO decomposed by carbonate transformed into anorthite and diopside at low temperature. Fe 2 O 3 promoted generation of low-temperature liquid phase, which facilitated densification process. The fired ceramics (60 wt% inferior clay) sintered at 1130 °C exhibited excellent properties with water absorption of 0.05%, linear shrinkage of 6.8% and flexural strength of 70 MPa. This batch was applied into an industrial experiment and 1160 m 2 qualified ceramics (ISO 10545-4:2004) were fabricated.

This paper provides a critical review on the current status and potential of biomass utilization in ferrous metallurgical processes, i.e., the blast furnace (BF) – basic oxygen furnace (BOF) route, the direct reduction (DR) – electric arc furnace (EAF) route, the scrap – EAF route and the other routes. In the BF-BOF route, biomass can be used as a fuel for iron ore sintering, or as a raw material for the production of bio-coke, and utilized for blast furnace injection. In the DR-EAF route, direct reduction iron can be produced form iron ore and biomass pellet. In the scrap – EAF route, biomass can be utilized in EAF through a cogeneration system. In addition, biomass can be utilized in magnetic separation of refractory low-grade iron ore, in reuse of iron and steel slag, or as an adsorbent for pollutant control, etc. The challenges and outlook of biomass utilization in metallurgical industry are also discussed in this paper.

Inorganic salts can be used as phase change materials (PCMs) for high temperature (>200 °C) thermal energy storage. Advantages of such PCMs include a wide range of phase change temperatures, high energy density, excellent physical/chemical stability and low price. However, applications of above salts based PCMs are greatly limited due to their corrosion to container materials and low thermal conductivity. These problems can be resolved by integrating salts to a porous skeleton, forming the so-called shape-stabilized PCMs (ss-PCMs). The ss-PCMs typically consist of an inorganic salt and a porous skeleton with the former for thermal energy storage and the latter both as a shape stabilizer and a thermal conductivity enhancer. The porous skeleton, made from packing of skeleton materials, is shown to effectively prevent leakage of loaded salts due to capillary force and surface tension. The generated porous skeleton also improves the thermal conductivity of ss-PCMs by providing a high thermally conductive heat transfer path. This review therefore focuses on the skeleton materials for high temperature salts based ss-PCMs, covering selection principles, types and current status of skeleton materials, formation mechanisms of porous skeletons generated from skeleton materials, and effects of different porous skeletons on mechanical and thermophysical properties of ss-PCMs, such as mechanical strength, phase transition temperature, latent heat, thermal conductivity, and cycling stability. Fabrication methods and applications of the ss-PCMs have been also summarized. To the best of our knowledge, this is the first profound review of skeleton materials for salts based ss-PCMs for high temperature applications.

Antibiotic resistant bacteria and genes, as emerging pollutants, are threatening public health. In this study, sulfidated micron zero-valent iron (S-mZVI) activated persulfate (SMP) system was used to eliminate antibiotic resistant E. coli (AR E. coli) and antibiotic resistant gene (ARG). S-mZVI exhibited excellent activation of persulfate, which could completely remove AR E. coli within 30 min. The oxidative damage of AR E. coli cell was systemically studied by transmission electron microscopy, fluorescence microscopy, flow cytometry and malondialdehyde analysis. Concentrations of TN and TOC in SMP system were conducted to evaluate the oxidation and mineralization ability for cellular substances in AR E. coli cell. Moreover, removal efficiencies of cell-associated ARG (TetB) and 16S rRNA in SMP system were 2.9 and 2.2 log, respectively. Study on the presence and role of main reactive oxygen species ( SO 4 · - and HO · ) in SMP system suggested that SO 4 · - and HO· are key factors when considering membrane lipid oxidation and removal of 16S rRNA and ARG. This study provided a promising treatment method to inhibit antibiotic resistance and revealed the oxidative damage of AR E. coli and gene under SO 4 · - involved system.

In this study, a novel swirl combustion modified device for steel slag was designed and enhanced with the objective of achieving highly efficient and clean coal combustion and also for achieving the whole elements utilization of coal. Coal ash and steel slag were melted in the combustion chamber and subsequently entered the slag chamber. The detrimental substances solidified and formed crystals, which allowed for the comprehensive utilization of the ash and slag. Our experiments mainly aimed to mitigate the formation of NOx, while using the heat and slag simultaneously during the coal combustion without a combustion efficiency penalty. The increase in the device’s energy efficiency and reduction in the NOx emissions are important requirements for industrialization. The experiments were carried out in an optimized swirling combustion device, which had a different structure and various coal feeding conditions in comparison to previously reported devices. The fuel-staged and non-staged combustion experiments were compared under different coal ratios (bitumite:anthracite). For the fuel-staged combustion experiments, the NOx concentration in the flue gas was observed to decrease significantly when the coal ratio of 1:1, an excess air coefficient of 1.2, and a fuel-staged ratio of 15:85 were used. Under these conditions, the flue gas temperature was as high as 1,620°C, while the NOx concentration was as low as 320 mg/m3 at 6 % O2. The air-surrounding-fuel structure that formed in the furnace was very beneficial in reducing the formation of NOx. In comparison to other types of coal burners, the experimental combustion device designed in this study achieved a significant reduction of NOx emissions (approximately 80 %).

This paper has adopted the weak magnet concentrate single reverse flotation and strong magnet concentrate reverse-direct flotation technology to conduct the industrial test on oxide ores of Bayan Obo. After the stability test, able to obtain oxide ore iron concentrate, TFe grade 65.92%, iron recovery rate 73.99%, K 2 O+Na 2 O, SiO 2 and F reaching 0.39%, 3.2% and 0.48% respectively, indicators great; the new process can reach the purpose of increasing iron and decreasing silicon, sodium and potassium.

Pilot trial of the detoxification of chromium slag in cyclone furnace and the preparation of glass-ceramics were investigated in a power plant in China. 10 wt.% chromium slag were mixed with pulverized bituminous coal and limestone as the raw materials of the cyclone furnace. Cr(VI) in chromium slag was reduced to Cr2O3 inside the cyclone furnace. The melt was water-quenched into frit and then fired into glass-ceramics with a laboratory ceramic roller kiln. The preparation and crystallization behavior of glass-ceramics were investigated with differential thermal analysis (DTA), physical and mechanical properties testing, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optimal flexural strength exceeding 90 MPa were achieved in firing temperature zone of 1170–1200 °C. Anorthite (CaAl2Si2O8) and diopside [Ca(Mg, Fe)Si2O6] can be identified in the glass-ceramics and CaAl2Si2O8 is the predominant crystal phase. Fine particles with average diameter of 200 nm distributed uniformly in the glass-ceramics. Granular crystals are intensively interconnected and constituted a crystal skeleton soaked in the glass matrix. Leaching toxicity test detected Cr(VI) of 0.016 and 0.010 mg/L of the water-quenched frit and glass-ceramics, respectively. This method provides an effective and comprehensive technique for the detoxification and utilization of chromium slag at low cost and large-scale.

Pilot trial of direct modification of molten blast furnace slag and production of high acidity coefficient slag wool fibers were investigated nearby a blast furnace. Molten blast furnace slag discharged from blast furnace and then directly flow into specialized modification furnace and quartz was simultaneously added into the molten slag as modification agent. The modified molten slag was electric heated to 1500–1550 °C and then the melt was produced into slag wool fibers through high-speed centrifugation method. Melt with acidity coefficient of 1.2, 1.4, 1.6 and 1.8 were investigated and fibers with corresponding acidity coefficient were produced. Slag wool fibers with shot content of 5.5, 5.8, 6.2, 6.8% and average diameter of 4.5, 4.9, 5.6, 6.4 μm for four samples were successfully produced, respectively. Total energy consumption and production costs decreased by 50–70% compared to traditional cupola furnace method. This method provides an energy-saving and emission-reduction technology for the direct utilization of molten blast furnace slag.

Staged reduction kinetics and characteristics of iron oxide direct reduction by carbon were studied in this work. The characteristics were investigated by simultaneous thermogravimetric analysis, X-ray diffraction (XRD), and quadrupole mass spectrometry. The kinetics parameters of the reduction stages were obtained by isoconversional (model-free) methods. Three stages in the reduction are Fe2O3→Fe3O4, Fe3O4→FeO, and FeO→Fe, which start at 912 K, 1255 K, and 1397 K, respectively. The CO content in the evolved gas is lower than the CO2 content in the Fe2O3→Fe3O4 stage but is substantially greater than the CO2 contents in the Fe3O4→FeO and FeO→Fe stages, where gasification starts at approximately 1205 K. The activation energy (E) of the three stages are 126–309 kJ/mol, 628 kJ/mol, and 648 kJ/mol, respectively. The restrictive step of the total reduction is FeO→Fe. If the rate of the total reduction is to be improved, the rate of the FeO→Fe reduction should be improved first. The activation energy of the first stage is much lower than those of the latter two stages because of carbon gasification. Carbon gasification and Fe x O y reduction by CO, which are the restrictive step in the last two stages, require further study.

Sintered diopside glass ceramics were successfully prepared from mixtures of blast furnace slag, fly ash and mining tailing. Results showed that sample C2 with relatively low iron oxides and mass ratio of CaO/SiO2 possessed the highest bending strength value among samples. A low content of iron oxide enhanced densification degree because pores were developed by reduction of ferric oxide into ferrous oxide. Moreover, a low CaO/SiO2 mass ratio also greatly promoted the densification process by prolonging the sintering time and delaying the crystallisation. In addition, sample C1 developed by one-stage sintering had a worse mechanical performance than that obtained by two-stage sintering although they had the same crystals. For all samples, despite of different compositions and sintering processes, the main crystal phases are augite and diopside ferrian.