Melting process and melt structure of fly ash/magnesium slag blends for the production of inorganic fibers

Fiber production from inorganic industrial solid wastes is an effective waste management strategy. Because of cost considerations, most enterprises generally use local solid wastes as raw materials to produce fibers. In this study, we explored the feasibility of producing fibers using fly ash and magnesium slag. The results show that the melting temperature of the blends composed of fly ash, magnesium slag, and a small amount of calcined dolomite first decreased and then increased with an increase in acidity coefficient (M_k) from 1.0 to 2.4_. The samples could form a eutectic system in the M_k range of 1.4–1.8, and therefore have a relatively low melting temperature in this M_k range. Fly ash could react with magnesium slag and calcined dolomite to form akermanite, gehlenite-magnesium, and anorthite at temperatures close to the melting temperature; therefore, these crystalline phases were the main reaction products formed in the samples with M_k values lower than 1.80. Anorthite reacted further with some Na-containing and Si-containing spieces to produce labradorite. Thus, the content of anorthite and labradorite rapidly increased and they became the major crystal phases in the blend samples with M_k values greater than 1.80. MAS-NMR spectroscopic analysis revealed that the network structure of the melts depended on the ratio of bridging oxygen to non-bridging oxygen; a high ratio of bridging oxygen to non-bridging oxygen could lead to the formation of a dense network structure in the melt. The blends of fly ash and magnesium slag can be used to produce wool fibers and continuous fibers. In addition, the suitable temperature ranges for the production of both types of fibers were determined. The drawing temperature for continuous fiber production depended on the degree of polymerization and structure of the melt.     

机械活化对粉煤灰提铝影响研究

为提高粉煤灰中铝提取率, 采用机械活化对粉煤灰进行预处理, 探讨了机械活化对粉煤灰焙烧-酸浸效果的影响。结果表明: 机械活化能提高粉煤灰比表面积、增加反应活性点, 促进活化反应的进行; 通过机械活化, 在Na₂CO₃与Al₂O₃物质的量比1.6、850 ℃下焙烧50 min后酸浸, 铝浸出率达到91.58%。     

Preparation of magnetic zeolite/chitosan composite using silane as modifier for adsorption of Cr(VI) from aqueous solutions

This study aimed to prepare an efficient, cost-effective, and separable magnetic zeolite/chitosan composite (MZFA/CS) adsorbent from solid waste to deal with the water pollution of Cr(VI). The MZFA/CS was characterized by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) techniques. Then, the effect of pH, temperature, initial concentration of Cr(VI) ions, and contact time was considered in the study. For a sorbent dose of 0.1 g in 50 mL of a Cr(VI) solution, at a contact time of 30 min, temperature of 30°C, and a pH of 3, an adsorption capacity (q_e) of 16.96 mg g⁻¹ was achieved. Adsorption kinetics and isotherm data obtained for all adsorption systems were well-fitted by pseudo-second-order and Langmuir models, respectively. The thermodynamic study suggested that the adsorption process is spontaneous and endothermic in nature. In summary, the adsorbent with better separability (Ms = 16.83 emu g⁻¹) and adsorbability was successfully fabricated.     

Effect of partial replacement of geopolymer binder materials on the fresh and mechanical properties: A review

The growth of demand for concrete raises concerns about the consumption of natural resources and ordinary Portland cement. Geopolymer composites show promise as a sustainable alternative for conventional cement concrete. Considering the wide range of potential geopolymer composites applications (including suitability for transportation infrastructure, underwater applications, repair and rehabilitation of structures as well as recent developments in 3D printing), the desired fresh and mechanical properties of the geopolymer composite may vary between applications: for example, rapid setting can be a merit for certain applications and a demerit for others. Therefore, the desired fresh and mechanical properties (e.g., workability, setting time, compressive strength, etc.) can be controlled for a given geopolymer source material through its partial substitution by natural or by-product materials. Recognizing the critical role of various replacement materials in enhancing the potential applications of geopolymer composites, the present review was undertaken to quantify and understand the effect of partial replacement by fly ash, metakaolin, kaolin, red mud, slag, ordinary Portland cement, and silica fume on the setting time, workability, compressive strength and flexural strength of various source materials addressed in the literature. The review also provides insights into research gaps in the field to promote future research.     

烧结时间对含铅玻璃制备微晶玻璃析晶及性能的影响

以铅玻璃与粉煤灰为原料，通过协同熔炼制备了微晶玻璃。通过XRD和SEM等手段研究了不同烧结时间下微晶玻璃的物相组成及显微结构，测定了微晶玻璃的密度、吸水率、维氏硬度和化学抗性。结果表明: 延长烧结时间对含铅玻璃加入量为40%(FG40)、50%(FG50)样品的晶相类型和晶化程度有影响，而对含铅玻璃加入量为60%(FG60)、70%(FG70)和80%(FG80)样品的影响较小。随着烧结时间延长，样品晶化程度提高，晶体长大，玻璃相减少。适宜的含铅玻璃加入量为50%~70%，对应的FG50、FG60、FG70样品最佳烧结时间分别为4 h、3 h、3 h。     

粉煤灰提铝残渣低温碱溶过程工艺研究

循环流化床粉煤灰“一步酸溶法”提取氧化铝工艺过程中产生的尾渣主要成分为无定形二氧化硅,且具有较高的活性,是制备白炭黑、分子筛、硅酸钠水玻璃的理想原料。对该提铝残渣在氢氧化钠溶液中的溶出过程做了研究,探讨了液固比、碱浓度、溶出时间、溶出温度工艺条件对二氧化硅和氧化铝溶出效果的影响。研究结果表明：在氢氧化钠碱液的浓度为4 mol/L、反应温度为70 ℃、液固比为6、反应时间为4 h的条件下,二氧化硅的溶出率最高,达到93%。提铝残渣碱溶后固体渣经XRD分析,其无定形二氧化硅基本已溶出,剩余物主要为锐钛矿与莫来石等。     

配加预处理脱硫灰对铁矿烧结基础特性的影响

 半干法脱硫灰堆弃处理占用土地且容易造成二次污染,将脱硫灰预处理后替代CaO熔剂配入烧结有望充分利用其中的熔剂组分,实现脱硫灰在钢铁企业的闭路资源化利用。研究了脱硫灰配加焦粉加热分解特性及替代CaO熔剂配加对铁矿粉烧结基础特性的影响。结果表明,配加1%焦粉可以有效提高脱硫灰分解率,减少CaSO₄的生成。随着预处理脱硫灰替代CaO比例的增加,铁矿粉同化温度和黏结相强度呈现先增加后减小的趋势;液相流动性呈现单调增加趋势,当替代比超过40%时,液相流动性形成了流动性很大的“假象”;黏结相微观结构表明,替代比例小于40%时,有利于烧结试样中铁酸钙的生成;综合考虑,最佳的替代比例应小于40%。     

锌冶炼铜烟灰中铟氧化浸出研究

以锌冶炼过程中的铜烟灰为原料,研究了硫酸浸出含铟铜烟灰过程中硫酸浓度、硫酸用量、浸出温度、浸出时间、氧化剂高锰酸钾用量等因素对铟浸出效果的影响。结果表明,当硫酸浓度300 g/L、液固比6 mL/g、反应温度90 ℃、反应时间5 h、高锰酸钾添加量0.3%时,铜烟灰中铟浸出率为65.73%。     

高灰熔点烟煤的分质利用技术研究

以河南平顶山矿区拥有气煤、肥煤、焦煤到无烟煤的多煤种为例，通过对不同煤层煤样的分析，发现主炼焦煤灰分低、结焦性好，非炼焦煤种硫分高、灰熔融性高，提出了优先生产炼焦精煤用于焦化工业，扩大中国炼焦煤资源；高硫和高灰分烟煤采用水冷壁气流床气化生产合成气；中煤、煤泥、矸石以及劣质煤，用于循环流化床燃烧发电；粉煤灰用来生产建材的煤炭分质利用路线，为煤炭清洁高效利用提供实施案例。     

气化灰基腻子粉的制备与性能研究

为实现气化灰综合利用和降低腻子粉制备成本，研究了利用气化灰替代水泥制备腻子粉的技术可行性。以气化灰和 42.5水泥为主要原料，配以少量的羟丙基甲基纤维素和可分散性乳胶粉，制备气化灰基腻子粉，实验考察原料配方变化对腻子粉的性能影响。研究结果表明：利用气化灰替代水泥制品制备腻子粉具有可行性。其中，气化灰替代 50%水泥时，腻子粉的粘结强度为 0.82 Mpa，各项性能均优于建筑外墙用腻子粉标准 JG/T 157—2009要求。在相同条件下，气化灰替代不超过 70%的水泥时，腻子粉的粘结强度及其他指标均满足建筑外墙用腻子粉标准 JG/T 157—2009要求。