炼钙还原渣和煤矸石制备聚合氯化铝的研究

采用煅烧后的煤矸石酸浸液与炼钙还原渣反应制备聚合氯化铝（PAC）。考察了炼钙还原渣投加量、反应时间和反应温度对PAC性能的影响,并采用红外、热重分析对其进行表征,结果表明：向酸浸液中加入一定量炼钙还原渣,在95 ℃下反应4 h,便可得到三氧化二铝质量分数为28.1%、盐基度为68.9%的固体PAC,符合GB/T 22627—2014《水处理剂 聚氯化铝》的要求。     

Porous alkali-activated material from hypergolic coal gangue by microwave foaming for methylene blue removal

Overall, 100% hypergolic coal gangue (HCG)-based geopolymer foams were produced by a novel saponification-microwave foaming combined route. Microwave foaming with and without expired vegetable oil was first used to produce CG-based geopolymer foams. Macropores were mainly generated by microwave foaming, and mesopores were mainly obtained by the addition of expired soybean oil that underwent a saponification reaction. The effects of the oil content on the density, porosity, pore morphology, compression strength, and methylene blue adsorption properties were studied. High total porosity (85.9–89.0 vol%) and acceptable compression strength (0.46–1.1 MPa) HCG-based geopolymer foams were produced. Foams with 12.59 wt% oil exhibited the best adsorption properties, with an adsorption capacity up to 9.4 mg/g and high removal efficiency of about 95.3%. These solid-waste-based porous components are promising monolithic adsorbents for wastewater treatment.     

钢渣与自燃煤矸石复掺对水泥性能的影响

运用正交试验研究了钢渣与自燃煤矸石的复掺比例、比表面积及石膏的种类等对复合水泥性能的影响。结果表明,钢渣与自燃煤矸石的复配比例是影响其强度的关键因素,其次分别为钢渣、自燃煤矸石的比表面积,而石膏的种类对其影响最小。试验优化的配比为：钢渣和自燃煤矸石的配合比为25%∶5%,钢渣比表面积为448m2/kg,自燃煤矸石比表面积为640m2/kg,石膏为3份天然二水石膏混合2份脱硫石膏,以及配比为钢渣和自燃煤矸石的配合比为25%∶5%,钢渣比表面积为516m2/kg,自燃煤矸石比表面积为470m2/kg,石膏种类为3份天然二水石膏混合2份改性磷石膏。     

Fabrication and application of porous materials made from coal gangue: A review

Coal gangue (CG), which is mainly generated during coal excavation, mining, and coal washing, is an industrial solid waste that is recognized as an environmental pollutant. The ever-increasing amount of CG produced is a serious threat to the ecological environment and property safety, especially in China, which is the largest coal producer and consumer in the world. Considerable studies have investigated means for utilizing CG worldwide. This review summarizes and discusses various porous inorganic materials made from CG, including cement-based porous materials, porous bricks, porous ceramics (cordierite and mullite) and glasses, porous geopolymers, zeolites, aerogels, and porous carbon materials. Different preparation processes and performances of each type of porous inorganic materials were reviewed. Porous CG-based materials can be used as promising adsorbents for the removal of various pollutants and have good potential for use in construction industry as well as catalyst material applications. Besides, porous materials obtained from CG have also been tested as slow-release fertilizers after the absorption of phosphate, as electrode materials, and as oil-in-water separation agents. The systematic summary of porous materials based on CG aims at promoting high-value-added applications for this waste. Future research directions for the use of CG as a raw material are also presented.     

Preparation of foamed ceramics from steel slag with high calcium and iron content

In this paper, steel slag foamed ceramics were fabricated by using steel slag, kaolin, feldspar, and quartz as main raw materials, and adding SiC as high-temperature foaming agent. The effects of steel slag content and SiC particle size on porosity and mechanical properties of foamed ceramics were researched. Results indicate that when content of steel slag is 40 wt%, and particle size of SiC is 20 µm, foamed ceramics exhibited optimized properties: water absorption rate of 2.59%, total porosity of 55.91%, bulk density of 1.33 g·cm⁻³, and compressive strength of 1.21 MPa. The results show that with the increase of steel slag content, the phase composition of foamed ceramics changes, and foam process is hindered. The increase of steel slag content contributes to the formation of diopside. Fe³⁺, Fe²⁺ in liquid phase enter into diopside by solid solution, the amount of liquid phase decreases. Liquid phase mass transfer slows down, and content of SiC in liquid phase decreases, so that the porosity decreases. At the same steel slag content, different SiC particle size affects the difference between pressure inside the closed pore and surface pressure, thereby the porosity changes.     

The preparation and characterization of porous alumina ceramics using an eco-friendly pore-forming agent

This work presents the preparation of porous alumina ceramics through the sacrificial phase method, using an eco-friendly material, namely waste coffee grounds, as a pore-forming agent. The effects of coffee grounds content in the green ceramic bodies on the linear and volumetric shrinkage, as well as the total and open porosity of the sintered product, were evaluated. The influence of the resulting porosity on mechanical properties of the prepared porous alumina was determined using Brazilian disk compression test for the determination of the indirect tensile strength of the prepared samples. Microstructure and pores morphology were characterized by scanning electron microscopy. Porosities in the range 35-54 vol% were achieved, by varying the coffee grounds content from 0 to 50 wt% in the green bodies. The indirect tensile strength of the final obtained porous alumina ceramic decreased accordingly from 57.4 MPa to 17.7 MPa.     

Effects of pore structure on thermal conductivity and strength of alumina porous ceramics using carbon black as pore-forming agent

In the present work, carbon black (CB) works as a pore-forming agent in the preparation of alumina porous ceramics. The pore structures (i.e. mean pore size, pore size distribution and various pores size proportions) were characterized by means of Micro-image Analysis and Process System (MIAPS) software and mercury intrusion porosimetry. Then their correlation and thermal conductivity as well as strength were determined using grey relation theory. The results showed that the porosity and mean pore size increased against the amount of CB, whereas the thermal conductivity, cold crushing strength and cold modulus of rupture reduced. The <2 μm pores were helpful for enhancing the strength and decreasing the thermal conductivity whereas the >14 μm pores had the opposite effects.     

Novel camphene/photopolymer solution as pore-forming agent for photocuring-assisted additive manufacturing of porous ceramics

This study proposes camphene/photopolymer solutions as a novel pore-forming agent for the photocuring-assisted additive manufacturing of porous ceramics. Unlike conventional techniques using molten camphene, solid camphene can be directly dissolved in the photocurable monomer hexanediol diacrylate (HDDA) at room temperature, which can then crystallize with a dendrite-like morphology based on phase separation at lower temperatures. This unique approach allows alumina suspensions to solidify at ―2 °C and then effectively be photopolymerized using a digital light processing engine, resulting in camphene-rich crystals surrounded by photopolymerized alumina/HDDA walls. Sintered samples exhibited a highly porous structure, with the pores created after the removal of the camphene-rich crystals. Two different pore sizes were obtained in the lower and upper regions of a single layer, due to a decrease in the solidification rate along the building direction, although their porosities were similar (～ 52 vol%). The porous samples exhibited a compressive strength of ～ 265 MPa.     

Preparation and properties of glass–ceramics derived from blast-furnace slag by a ceramic-sintering process

Glass–ceramics were synthesized using ground blast-furnace slag and potash feldspar additives by a conventional ceramic-sintering route. The results show 5 wt% potash feldspar can enhance the sintering properties of blast-furnace slag glass and the results glass–ceramics have desirable mechanical properties. The main crystalline phase of the obtained glass–ceramic is gehlenite (2CaO·Al₂O₃·SiO₂). A high microhardness of 5.2 GPa and a bending strength higher than 85 MPa as well as a water absorption lower than 0.14% were obtained.     

少掺量钢渣矿渣水泥的研究

在高掺量矿渣水泥中掺少量可看作低质熟料的钢渣,弥补由于熟料掺量少造成的碱性不足。当混合材的总量为６０％～６５％时,钢渣掺量控制在１５％～２０％左右,只需采用普通外加剂,就能够生产４２５水泥。工业性试验在太钢东山水泥厂进行。     

Novel design of elongated mullite reinforced highly porous alumina ceramics using carbonized rice husk as pore-forming agent

A facile strategy for the fabrication of elongated mullite reinforced porous alumina ceramics (PACs) using carbonized rice husk (CRH) as pore-forming agent and silica source is reported for the first time. A large amount of elongated mullite is synthesized in pores due to the reaction of amorphous silica in CRH skeleton and alumina ceramic powder. Elongated mullite acts as the bridges between pore walls, enhancing the compressive strength of PACs. Furthermore, secondary pores from the intersection of elongated mullite is favor of decreasing of the thermal conductivity. High performance PAC with porosity of 74.3% has been fabricated by employing 25 wt% CRH, which possesses relatively low thermal conductivity of 0.189 W/(m•K) and ultra-high compressive strength of 45 MPa. Its comprehensive performance is much better than that of existing ceramic materials. Our findings present a facile, eco-friendly and effective approach to fabricate high performance PACs as the high-temperature thermal insulation materials.     

An eco-friendly permeable brick with excellent permeability and high strength derived from steel slag wastes

Utilisation of industrial solid wastes to prepare products with high added value is an effective way that could relieve environmental pollution and create huge economic benefits. In this work, steel slag based permeable brick (SSPB) was successfully prepared by liquid phase sintering. The BSE-EDS results indicate that the microstructure of the SSPB becomes dense because of the formation of a small amount of glass-liquid phase (Na-K-Ca-Fe-Si-O glass system). The effect of sintering temperature on various properties of the SSPB was systematically studied. It is found that as the sintering temperature increases from 1210 to 1300°C, the permeability deceases gradually, as well as the apparent porosity, water retention and water absorption. In contrast, the bulk density and mechanical strengths show gradually increasing trends. Most important of all, the SSPB sintered at 1270°C for 1 hour shows an excellent permeability (5.70 × 10⁻² cm/s) and high mechanical strengths (compressive strength, 36.6 MPa; bending strength, 6.8 MPa). The prepared SSPB is not only likely to be a new type of permeable brick for sidewalk construction, but also relieve greatly environmental pollution from steel slag because of the high utilisation rate of steel slag (as high as 90%).     

Porous mullite ceramics derived from coal fly ash using a freeze-gel casting/polymer sponge technique

The objective of this study was to prepare highly porous mullite ceramics with relatively large-sized pores and improved compressive strength using a freeze/gel casting route combined with polymer sponge for recycling of coal fly ash into high value-added ceramics. In this work, a tertiary-butyl alcohol /coal fly ash slurry system with an appropriate addition of Al₂O₃ was used. A reticulated structure with large pore size of 220–300 μm, which formed on burnout of polyurethane was obtained; then, the skeletons consisted mainly of more dense crystalline phases together with a few fine pores (<3 μm). The rod-shaped mullite crystals with an aspect ratio of >3.7 (~4 μm in diameter) seen to have grown within the silicate melts existed. The compressive strength of the sintered porous materials increased in the reverse order of the degree of porosity, i.e. low porosity gave a high compressive strength. The porous materials with an average porosity of 61.6 %, sintered at 1600 °C with 70 wt.% solid loading showed the maximum average compressive strength (~45 MPa).     

以钢渣为原料合成层状双氢氧化物及其结构表征

以钢渣为原料,醋酸为浸出介质,在一定条件下得到浸出液,利用共沉淀法合成了Ca-Mg-Al-Fe四元层状双金属氢氧化物(LDHs),探讨了pH、晶化温度和晶化时间对Ca-Mg-Al-Fe四元LDHs层状材料合成的影响,采用XRD、XRF、SEM、FT-IR、TEM、DTA/TG和BET对样品进行了表征。研究表明,pH对层状材料合成的影响最大,pH在10.5～11.8可形成纯相水滑石;晶化温度和晶化时间是影响晶格参数和层间距的重要因素,随温度及时间的增加,其晶格参数a、c及层间距均先减小后增大;LDHs的晶粒尺寸沿a轴方向比沿c轴方向大。当pH 11.8,晶化温度150℃,晶化时间16 h时,合成的LDHs层状材料结构规整、晶型良好、层状结构明显、孔径较大且热稳定性良好。     

Effect of CaO/SiO2 ratio on phase transformation and properties of anorthite-based ceramics from coal fly ash and steel slag

Anorthite-based ceramics were produced entirely from coal fly ash and steel slag. The effect of the CaO/SiO₂ ratio (0.12–0.8) on the phase transitions was examined by adding steel slag to coal fly ash in the range of 10–50 wt%, and a temperature range of 900–1200 °C. The influence of CaO/SiO₂ and sintering temperatures on the technological properties were assessed by response surface methodology (RSM) and correlated with the phase changes. The results revealed that anorthite was the main phase for the CaO/SiO₂ ratio ranging from 0.12 to 0.56, while at 1200 °C, a ratio of 0.8 involved a high content of gehlenite. RSM showed that the CaO/SiO₂ ratio was the main influencing factor on the density, while the variation of apparent porosity and compressive strength were more affected by sintering temperature. The crystallisation of the anorthite phase significantly enhanced the properties of the obtained ceramics, whereas the appearance of gehlenite reduced the mechanical strength. The optimum conditions to fabricate anorthite-based ceramics with suitable properties were found to be a CaO/SiO₂ ratio of 0.46 and a temperature of 1188 °C. The optimised anorthite-based ceramic exhibited a low thermal conductivity (0.39 W/m.K) and a dielectric constant of 6.03 at 1 MHz, along with a compressive strength of 41 MPa, which makes this sample a potential candidate for insulator applications.     

Preparation and properties of porous Al2O3-based ceramics by gel casting using MgO as a gelling and consolidating agent

Low-cost and environment-friendly MgO was used as a new gelling and consolidating agent to fabricate porous Al₂O₃-based ceramics via a gel casting routine. Effects of 800°C calcined additions of MgO (.5, 1.0, 1.5, and 2.0 wt%, respectively) on open porosity (OP), pore size distribution, gas flux, and microstructure of the porous ceramics were investigated deliberately. The experimental results showed that 800°C calcined MgO exhibits excellent gelling and consolidating performance at 80°C, mainly owing to the hydration reaction between MgO and H₂O and thus results in high-quality porous Al₂O₃-based ceramics without deformation and cracking. The Al₂O₃–water suspensions with different MgO additions have good flowability at room temperature. Moreover, water absorption, open porosity, and gas flux of the as-prepared porous ceramics increase remarkably with rising of MgO addition. Furthermore, MgO addition significantly suppresses the abnormal growth of Al₂O₃ grains, and thus the microstructure of the porous Al₂O₃-based ceramics becomes more uniform. This technique of gel casting using MgO as a new gelling and consolidating agent offers an alternative routine for a large-scale production of porous ceramics.     

用电石渣生产水泥的立窑窑灰回收利用技术

将用电石渣生产水泥的立窑窑灰,采用预加水成球工艺成球后与生料和一起入窑煅烧,提高了熟料质量、改善了操作环境,降低了生产成本。     

Hydrotreating a distillate liquid derived from subbituminous coal using a sulphided CoO-MoO3-Al2O3 catalyst

A coal-derived heavy naphtha distillate containing 4.76, 0.51 and 0.004 wt% oxygen, nitrogen, and sulphur, respectively, has been hydro-treated. Even with severe processing conditions, the conversions of heteroatom species is less than desired. An empirical equation based on the experimental data indicates greater conversions would be attained at greater pressures and residence time. Severe catalyst deactivation is attributed primarily to carbonaceous deposits. However, smaller concentrations of zinc also accumulate on the catalyst.     

Effects of Al/Na and heat treatment on the structure and properties of glass ceramics from molten blast furnace slag

Glass ceramics with different Al/Na molar ratio from blast furnace slag were prepared using conventional melting-casting method. The structure and properties of glasses or glass ceramics were investigated by DSC, Raman, MAS NMR, XRD, and SEM. The DSC results indicated that the thermal stability (ΔT = T_c-T_g) and crystallization temperature (T_c) of the parent glass firstly increased and then decreased when Al/Na exceeded 1.21. The Raman and ²⁷Al MAS NMR spectra analysis revealed that [AlO₆] increased positively with Al₂O₃/Na₂O. The calculation of Qⁿ ([SiO₄] units with bridging oxygen atoms number of n) suggested an obvious decline of (Q⁰+Q²)/(Q¹+Q³) and that [SiO₄] mainly existed in the form of Q¹ when Al/Na exceeded 1.21, which accorded closely with T_c variation. The crystallization results determined by XRD showed that as Al/Na increased, the main crystal phase was transformed from akermanite to gehlenite and nepheline disappeared. Glass ceramics with Al/Na of 1.48 nucleated at 780 °C for 2 h and crystallized at 880 °C for 3 h exhibited the maximum value of flexural strength. Orthogonal experiment (L9(3⁴)) were carried out to investigated the optimum heat treatment of glass ceramics with a Al/Na of 1.48. The analyses indicated that nucleation time variation has little influence on the flexural strength, and the optimum heat treatment was determined as 760 °C – 1 h–900 °C – 1 h and the flexural strength was characterized as 81.310 MPa.     

Synthesis,characterization and assessment of poly(urethane-co-pyrrole)s derived from castor oil as anticorrosion coatings for stainless steel

Electrically conductive and organic-solvent soluble poly(urethane-co-pyrrole)s (CPUPYs) were prepared by oxidative polymerization of pyrrole with a hydroxyl-terminated polyurethane prepolymer in the presence of ceric (IV) ammonium nitrate. Direct electrodeposition of CPUPYs from their appropriate solvent on the surface of stainless steel working electrode by continuous cycling potential between −0.8 and 1.8 V vs. Ag/AgCl with a scan rate of 0.03 V/s led to smooth, strongly adhered and insoluble coatings. All materials were characterized by conventional spectroscopic methods, and their physical and viscoelastic properties were evaluated. The corrosion protection properties of the CPUPYs-coated stainless steels were measured by Tafel polarization and electrochemical impedance spectroscopy. A substantial lower corrosion current, higher corrosion potential and higher charge transfer resistance values of CPUPYs-coated steels were recorded and comparisons were made with those properties of bare steel as well as parent polyurethane and neat polypyrrole-coated stainless steel. Excellent anticorrosive efficacy of newly developed CPUPYs-coated steel was achieved.