添加物对铝碳耐火材料防氧化涂料抗氧化性能的影响

以SiO2-A l2O3-B2O3-Na2O-K2O-CaO系釉料为基料,分别添加质量分数为10%、30%、50%、70%的氧化物(粒度均<0.076 mm的石英和刚玉粉)和非氧化物(粒度均<0.076 mm的碳化硅和硅粉),以水玻璃为结合剂配制涂料,首先研究了涂料半球温度的变化,然后将涂料涂覆在铝碳材料样块的表面,考察其抗氧化性能(以铝碳样块在200~1 300℃氧化后的质量损失率表征),并采用SEM观察了涂层结构。结果表明:加入氧化物SiO2、A l2O3以及非氧化物SiC、Si,均使涂料的半球温度升高;A l2O3和SiC的加入能增强涂料的防氧化作用,而SiO2、Si的加入使涂料的防氧化作用降低。     

原位生成O''''-SiAlON晶须增强铝碳耐火材料

以板状刚玉、石墨为主要原料,基质部分分别添加3%、5%和7%的O’-SiAlON前驱体混合粉(即β-Si3N4微粉、SiO2微粉和α-Al2O3微粉的混合球磨粉),以酚醛树脂为结合剂制成试样,于200℃烘烤后,在空气中埋(SiO2 C)混合粉,分别于1000℃、1300℃、1500℃保温3h原位合成了含O’-SiAlON晶须的铝碳耐火材料。对烧后试样的物理性能、物相及显微结构进行了分析,并对烧结有重要影响的反应进行了热力学分析。结果表明:埋(SiO2 C)混合粉能有效抑制反应体系中SiO2在高温烧结过程中的分解,从而促进O’-SiAlON晶须的原位生成。1500℃时,含有O’-SiAlON前驱体混合粉的试样原位生成了针状和絮状的O’-SiAlON晶须,这些晶须交织于试样的骨料与基质之间,能显著增强试样的强度;且随着O’-SiAlON前驱体含量的增加,试样的强度逐渐增加。     

水基SiC浆料的喷雾造粒特性

以水为液体介质,制备分散稳定的水基SiC料浆,并利用喷雾造粒技术对水基SiC浆料进行造粒,研究了碳化硅浆料固含量及喷雾干燥工艺对造粒粉特性的影响。研究结果表明:浆料固相含量对造粒粉体粒径分布影响明显,粉体粒径随固含量的增加而增大。在最佳的干燥工艺条件下,碳化硅粉体流动性得到较大改善,素坯密度增加,陶瓷力学性能提高。     

含镍、铬复合氧化球团的制备工艺

 利用廉价的低品位铬铁矿精矿以及红土镍矿制备含镍、铬复合球团,用于高炉生产含镍和铬不锈钢母液,对于保障不锈钢产业的可持续发展具有重要意义。系统研究含镍、铬球团制备工艺,探究红土镍矿配比、铬铁矿配比以及添加剂对球团强度的影响。结果表明,当混合料配比为45%红土镍矿+15%铬铁矿+40%铁精矿时,添加7.7%添加剂的混合料经高压辊磨预处理后可制备出合格生球,在预热1 000 ℃+12 min,焙烧(1 220～1 250 ℃)+12 min的条件下可获得抗压强度大于2 500N/个的成品球团,可用于高炉生产铁、镍和铬三元不锈钢母液。     

Development of a fast,lean and agile direct pelletization process using experimental design techniques

A novel hot melt direct pelletization method was developed, characterized and optimized, using statistical thinking and experimental design tools. Mixtures of carnauba wax (CW) and HPMC K100M were spheronized using melted gelucire 50–13 as a binding material (BM). Experimentation was performed sequentially; a fractional factorial design was set up initially to screen the factors affecting the process, namely spray rate, quantity of BM, rotor speed, type of rotor disk, lubricant–glidant presence, additional spheronization time, powder feeding rate and quantity. From the eight factors assessed, three were further studied during process optimization (spray rate, quantity of BM and powder feeding rate), at different ratios of the solid mixture of CW and HPMC K100M. The study demonstrated that the novel hot melt process is fast, efficient, reproducible and predictable. Therefore, it can be adopted in a lean and agile manufacturing setting for the production of flexible pellet dosage forms with various release rates easily customized between immediate and modified delivery.     

Estimation of pellet size and strength of limestone and manganese concentrate using soft computing techniques

This paper presents a soft computing approach to estimate wet or green pellet size and strength and signifies the importance of individual process parameter. A huge portion of available minerals and materials is in the form of fine powder that makes their management and utilization a tedious job. Pelletization, a size enlargement technique, is used to tackle aforementioned problems and provides benefits such as ease of handling and storage, convenient transportation and improved process efficiency. Besides other characteristics, pellet size and strength are of prime significance and their accurate estimation can enhance the product quality. Real-life constraints (e.g., time in conducting experiments, repetition of experiments considering measurement errors, availability of resources, etc.) pose difficulties in generating sufficient experimental data at the laboratory. Hence, the concept of random population generation of genetic algorithm is exploited to fulfill data requirement where fitness functions are formulated using multiple regression. Better visualisation of pellets attributes and operating conditions is done through self-organizing map which also helped in deducing some important facts. Sensitivity analysis and construction of learning curves is also performed in present study. Finally, multilayer perceptron, a popular supervised neural network model, is applied on synthetic data to approximate pellet properties. Agreement between estimated and corresponding experimental values ascertained that neural network based system can be employed as an effective and credible tool to anticipate characteristics of wet pellets.     

喷雾造粒SiC粉料在成型过程中的破碎行为

采用压力喷雾造粒的方式对ＳｉＣ粉体进行喷雾造粒处理，研究了喷雾造粒过程中工艺条件和浆料中粘合剂含量对成型过程中粉料颗粒破碎行为的影响。实验结果指出：喷雾造粒过程中粘合剂含量过多或进口热风温度过高，都会使喷雾造粒粉料颗粒的团聚强度增加，在成型过程中不易破碎，残留在素坯中的硬团聚将对烧结致密化产生不利影响。ＳｉＣ粉体在雾造粒时最佳粘合剂含量和进口热风温度分别为５０ｍｌ／ｋｇ和２４０℃。     

Corrosion Resistance of High-Alumina Graphite Based Refractories to the Smelting Reduction Melts

1 Introduction The corrosion resistance of the refractories is one of the imperative problems for the development of smel- ting reduction with iron bath[1 ~4]. The Al2O3-C based refractories have been widely and successfully used in the metallurgy industr…     

Important parameters for the manufacture of slow-release matrix pellets with an aqueous dispersion of quaternary poly(meth)acrylates in the rotary fluidized bed

The manufacture of slow-release matrix pellets with an aqueous dispersion of quaternary poly(meth)acrylates was investigated in the rotary fluidized bed. By considering the moisture content of the fluidized bed to be the key process parameter, it was measured on-line throughout the whole manufacturing process. A specially designed sampling device opened new ways to apply NIR spectrometry in laboratory scale processes. It was shown that reproducibly improved pellet properties can be achieved by reproducing the moisture content of the (rotary) fluidized bed. Moisture plateaus proved to be a suitable way to optimize the sphericity of the pellets. Premoisturizing was found to be a very effective tool to achieve slow-release dissolution of the model drug theophylline.