烧结处理小矿山精矿的应用研究

研究小矿山精矿的性质，分析小矿山精矿对烧结过程的影响，提出了增加小矿山精矿配入量的途径及方法．     

Al2O3-Al-C材料加热过程的变化

按w(板状刚玉)=84%,w(铝粉)=8%,w(α-Al2O3微粉)=6%,w(鳞片石墨)=2%的配比配料,外加3%热固性酚醛树脂作结合剂,成型后于200℃烘烤24h。在埋炭条件下于600～1400℃保温3h加热处理,冷却后测量试样的线变化率、显气孔率和常温耐压强度,并分析部分试样的孔径分布、相组成和显微结构,同时测定烘烤后试样在600℃、800℃、1000℃、1200℃和1400℃下的热态抗折强度,以分析该材料在加热过程的变化。结果表明,试样在600～1400℃埋炭加热过程中的变化可大致分为3个阶段:1)600～800℃,金属Al于660℃熔化,促进试样致密化,在800℃时已有少量Al4C3和AlN生成,使加热后试样的致密度和强度增大;2)800～1200℃,大量生成Al4C3和AlN,Al4C3和AlN填充在刚玉骨架结构中,试样的显气孔率进一步减小,常温耐压强度和热态抗折强度进一步增大;3)1200～1400℃,金属Al消失,Al4C3含量减少,部分与N2反应转化为AlN,试样的显气孔率略有降低,常温耐压强度和热态抗折强度略有增大。由此可见,随着加热温度的提高,材料的结合方式从碳结合转变为碳和金属铝复合结合,最后逐渐转变为碳和非氧化物复合结合。     

Mn对含炭耐火材料抗渣侵蚀性的影响

以烧结板状刚玉、锆莫来石、天然鳞片状石墨为主原料 ,酚醛树脂为结合剂 ,Al、Si、B4C、Mn粉为添加剂 ,经 1 4 50℃埋炭烧成后 ,制成铝炭和铝锆炭系列试样 ,并对各试样的抗渣侵蚀性能进行了对比研究。结果表明 :在铝锆炭材料中 ,当Mn与Al、Si复合加入且Mn与C的质量比为 1∶4时 ,试样的抗侵蚀性和渗透性均较好 ;在铝炭材料中 ,当Mn与Al、Si、B4C复合加入且Mn与C的质量比为 1∶4时 ,试样的抗渗透性较好     

炼铁原、燃料检、实验系统的建立与应用

介绍了济钢炼铁原、燃料检、实验系统的构成，主要性能特点，使用过程中的经验教训。此系统使用后年节省检、实验费用95．64万元。     

Use of crospovidone as pelletization aid as alternative to microcrystalline cellulose: effects on pellet properties

Background: Microcrystalline cellulose (MCC) is the most important pelletization aid in extrusion/spheronization. Because of known disadvantages, the search for substitutes is ongoing. In this context, crospovidone has proven to offer substantial advantages as pelletization aid because of its ability to turn low-soluble active ingredients into fast-dissolving stable pellets. Method: Pellets from crospovidone with different amounts of paracetamol, hydrochlorothiazide, and spironolactone as model drugs were prepared by extrusion/spheronization. For comparison, pellets with MCC as extrusion aid were also produced. The pellets of different formulations were evaluated in terms of yield, aspect ratio, mean Feret diameter, 10% interval fraction, tensile strength, disintegration, and drug release profile. Results: Only crospovidone types exhibiting small particle sizes are suitable as pelletization aid. While maintaining the pharmaceutical quality aspects, it was possible to incorporate up to 60% (w/w) active pharmaceutical ingredients (API) into pellets with crospovidone. The most distinguished differences between pellets based on crospovidone and MCC are the disintegration and drug release behavior. The pellets containing binary mixtures of the low-soluble APIs and crospovidone resulted in fast release in contrast to the pellets with MCC as pelletization aid, which exhibited a slow release. Conclusion: Crospovidone shows an excellent behavior as pelletization aid and produces fast-releasing pellets even with low-soluble APIs.     

Comparison of mechanical properties of ground corn stover,switchgrass, and willow and their pellet qualities

Mechanical and physical properties of ground corn stover, switchgrass, and willow were measured and compared in addition to the quality of pellets. Biomass was size-reduced with two different screen sizes (3.175 and 6.35?mm) and conditioned to obtain samples at two different moisture contents (17.5 and 20% on wet basis). Ground switchgrass had the smallest and willow had the highest D₅₀ when size-reduced with the same screen size. Hydrostatic triaxial compression tests were performed using the cubical triaxial tester to determine the bulk modulus, compression index, and spring-back index at specific unloading pressures (20, 45, 70, and 95?kPa). The trends of pressure vs. volumetric strain and void ratio vs. natural log of pressure were similar for all three materials; however, the magnitudes were different. Willow, size-reduced with 3.175?mm screen size at 17.5% wet basis, had the highest bulk modulus among different conditions of all the three biomass. Pellet durability values for all the three materials were higher than 80%. Corn stover pellets formed with 3.175?mm screen size at 20% wet basis had the highest diametral tensile and axial compressive strengths among different conditions for all the three biomass, however the values were not significantly different (p?>?0.05).     

Iron Ore Pellet Dustiness Part II: Effects of Firing Route and Abrasion Resistance on Fines and Dust Generation

Iron ore pellets abrade during their production and handling, which lowers product quality and leads to dustiness issues. Pellets were collected from a variety of plants (operating either Straight-Grate (SG) or Grate-Kiln (GK) furnaces) to understand whether furnace type affects fines and dust formation. Results showed that pellets fired in SG furnaces were less abrasion-resistant (3.5 × lower) than pellets fired in GK furnaces. Concurrently, laboratory pellets were prepared using various ores, binders, and firing temperatures. These were tested to understand the relationship between abrasion index and dustiness. AI was observed to range from 1 to 14%. Dustiness, determined via AI and size distributions of abrasion progeny, ranged from 0.2 to 1.6%. For AI greater than 5%, AI can be used to indicate potentially high levels of dust. For AI less than 5%, there was a poor correlation between AI and dustiness. This was explained by the observation that as AI decreased, the abrasion product fineness increased. The results from parts I and II of this investigation suggest that material loss and levels of pellet dustiness may be significantly affected by pellet quality up to a certain point. Poorly fired pellets will be dusty during handling and transportation, while well-fired pellets will generate less – but finer – material as their quality improves. This could lead to little observed changes in dust generation over a wide range of pellet quality. Dust generation at each site would then depend on the quantity of material produced and their extent of handling.     

A New On-Line Method for Predicting Iron Ore Pellet Quality

The Abrasion Index (AI) describes fines generation from iron ore pellets, and is one of the most common indicators of pellet quality. In a typical pellet plant, dust is generated during the process and then captured. Can the dust be measured and used to predict AI? In this paper, the feasibility of using airborne dust measurements as an indicator of AI is investigated through laboratory tests and using data from a pellet plant. Bentonite clay, polyacrylamide and pregelled cornstarch contents, and induration temperature were adjusted to control the abrasion resistance of laboratory iron ore pellets. AI were observed to range from approximately 1% to 12%. Size distributions of the abrasion progeny were measured and used to estimate quantities of PM₁₀ (particulate matter with aerodynamic diameter less than 10 µm) produced during abrasion. A very good correlation between AI and PM₁₀ (R² = 0.90) was observed using the laboratory pellets. Similarly, a correlation was observed between AI and PM measured in the screening chimney at a straight-grate pelletization plant in Brazil, with an R² value of 0.65. Thus, the laboratory and industry data suggest that measuring dust generation from fired pellets may be an effective on-line measurement of pellet quality. The data also showed that particulate emissions from pelletization plants may be directly affected by AI.     

Important Parameters for the Manufacture of Slow-Release Matrix Pellets With an Aqueous Dispersion of Quaternary Poly(meth)acrylates in the Rotary Fluidized Bed

ABSTRACT

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.     

二氧化硅喷雾造粒粉体的热处理工艺研究

研制了一种以SiO2为基体的高温可磨耗封严涂层,为了改善二氧化硅喷雾造粒粉体的性能,研究了热处理工艺对粉体松装密度、流动速度及粒度分布的影响。结果表明,热处理过程中伴随着SiO2颗粒的烧结,热处理温度对粉体性能的影响较热处理时间更为显著,随着温度的升高,喷雾造粒SiO2球逐渐烧结,粉体粒度减小,松装密度增加,流动性提高,采用1000～1050℃、30～60min的工艺对粉体进行热处理能够获得最优的粉体性能。