利用人工神经网络模型预测球团矿还原粉化指数

印度JSW钢铁公司是一家年产钢700万t的联合钢铁企业,其炼铁单元由2座COREX和3座高炉组成。COREX和高炉用球团由一个年产420万t的带式焙烧机球团厂供给。作为一项重要的冶金性能指标,球团的还原粉化指数(RDI)要求满足COREX和高炉冶炼的要求。通过建立神经元网络模型和敏感度分析,研究了给料率、料层高度、焙烧温度、干透点温度、COREX煤气单耗、膨润土的添加量、生球水分、生球碳含量、以及成品球的MgO、Al2O3含量和碱度等12个因素对球团RDI指标的影响,并对焙烧机生产球团的RDI(-6.3mm)和RDI(-0.5mm)进行了预测。结果表明,球团中MgO、CaO/SiO2,生球碳含量和Al2O3含量对球团RDI指标影响较大。预测结果与实际的数据误差低于4%。研究得出:①生球的MgO、氧化铝和碳含量以及二元碱度对球团RDI有重要影响。②随着球团MgO含量和球团二元碱度的升高,球团RDI(-6.3mm)和RDI(-0.5mm)得到改善。③随着生球中氧化铝含量的增加,球团RDI升高,因此应尽量使用低氧化铝含量的铁矿粉来降低球团中的氧化铝。随着生球中氧化铝和碳含量的增加,球团RDI(-6.3mm)和RDI(-0.5mm)有所降低。④提高球团二元碱度和MgO含量的同时,降低生球碳含量可以改善球团的RDI。因此需要对它们的配比进行优化。⑤二元碱度0.50～0.55,MgO质量分数0.35%～0.45%,生球碳质量分数1.15%～1.20%,焙烧球氧化铝质量分数低于2.5%,FeO质量分数低于0.60%时,可望得到较低的RDI。⑥相对于球团中的碳和CaO含量,最优的焙烧温度可以改善球团的RDI(-6.3mm)和RDI(-0.5mm)。⑦高给料率和较高的料层高度会使球团的RDI(-6.3mm)和RDI(-0.5mm)升高。     

铁坑褐铁矿石压球-磁化焙烧-弱磁选试验

为使铁坑褐铁矿石能得到高效利用,采用压球-磁化焙烧-弱磁选工艺对其进行了选矿试验,主要考察了成球条件对球团强度的影响及磁化焙烧条件和磨矿细度对铁精矿指标的影响。试验结果表明：在内配煤、水、黏结剂CMC与原矿的质量比分别为20%、10%、0.5%,压力为190 kN的条件下压球,可使球团的强度达到要求;球团在外配煤与原矿的质量比为15%、焙烧温度为900 ℃、焙烧时间为50 min的条件下磁化焙烧,焙烧矿磨至-0.074 mm占85%后进行磁场强度分别为159.2和119.4 kA/m的1粗1精弱磁选,可获得铁品位为63.55%、SiO₂含量为6.38%、铁回收率为83.54%的铁精矿。     

Plate Water Absorption as an Assessment Tool for Organic Binders

Plate water absorption has been traditionally used to assess the binding ability of bentonite clay binders for iron ore concentrate pelletization. Until 1997, there was an accepted test by ASTM, but due to inconstant data this method was withdrawn. This value, however, is still used by some pelletization operations to gauge the efficacy of their bentonite. This test procedure has only been investigated on inorganic binders and never organic binders. This paper seeks to confidently prove that PWA can be used to accurately determine the efficacy of starch binders both alone and in conjunction with bentonite. The role of bentonite as a binder for iron ore concentrate is not only to hold agglomerates together during high temperature operations. But during pelletization it can also mitigate many times its own weight in water. This water absorption capacity aids in retarding the growth rate of pellets, as faster growing pellets tend to be weaker. The value of this water absorption, known as plate water absorption (PWA), is used as a metric to determine the strength and quality of the resulting pellets by industrial pelletizing facilities. As new low silica binders seek to replace bentonite, they too must take on the role of moisture mitigation. This study has shown that starches with lower water absorption capacities tend to have lower compressive strengths. As the water absorption capacity increases so too does the compressive strength. When using only starch, higher absorption capacities lead to lower compressive strengths of pellets exposed to elevated temperatures. When bentonite is used in conjunction with starch, higher water absorption mixtures do exhibit an increase in strength when heated.     

回转窑结圈的原因分析及改进措施

对豫河公司投产初期回转窑结圈现象频发的问题进行了分析,提出了改进措施。通过对原燃料条件、工艺参数、设备等方面进行改进后,提高了生球质量并优化热工制度,有效地解决了结圈问题。     

Sustained-release alginate-chitosan pellets prepared by melt pelletization technique

Context: Alginate-chitosan pellets prepared by extrusion-spheronization technique exhibited fast drug dissolution.

Objective: This study aimed to design sustained-release alginate pellets through rapid in situ matrix coacervation by chitosan during dissolution.

Methods: Pellets made of alginate with chitosan and/or calcium acetate were prepared using solvent-free melt pelletization technique which prevented reaction between processing materials during agglomeration and allowed such reaction to occur only in dissolution phase.

Results: Drug release was retarded in pH 2.2 medium when pellets were formulated with calcium acetate or chitosan till a change in medium pH to 6.8. The sustained-release characteristics of calcium alginate pellets were attributed to pellet dispersion and rapid cross-linking by soluble Ca²⁺ during dissolution. The slow drug release characteristics of alginate-chitosan pellets were attributed to polyelectrolyte complexation and pellet aggregation into swollen structures with reduced erosion. The drug release was, however, not retarded when both calcium acetate and chitosan coexisted in the same matrix as a result of chitosan shielding of Ca²⁺ to initiate alginate cross-linkages and rapid in situ solvation of calcium acetate induced fast pellet dispersion and chitosan losses from matrix.

Conclusion: Similar to calcium alginate pellets, alginate-chitosan pellets demonstrated sustained drug release property though via different mechanisms. Combination of alginate, chitosan and calcium acetate in the same matrix nevertheless failed to retard drug release via complementary drug release pattern.     

含钒渣对铝碳材料的侵蚀

为了探讨含矾渣对铝碳材料的侵蚀机制,用动态感应抗渣法研究了w(V2O5)=10%、碱度2.8,w(V2O5)=6%、碱度2.8,w(V2O5)=6%、碱度1.44的3种含钒渣对铝碳材料的侵蚀。结果表明:随着V2O5含量(w)由6%增加到10%,铝碳材料的熔损指数增加;随着碱度的增加,铝碳材料的熔损指数也增加;添加电熔镁砂有助于提高铝碳材料的抗侵蚀性能。显微分析表明:V、Ti元素渗透能力强,渗透深,而尖晶石可固溶少量V2O5、MnO及FeO。     

Modeling of iron ore pelletization using 3 ** factorial design of experiments and polynomial surface regression methodology

The process of size enlargement or agglomeration finds a variety of applications in material processing and utilization. Pelletization is one such process which uses water as medium and revolving units (Disc/Drums) to form spherical pellets from fine particulates. Green or wet pelletization is the first step in pelletization process and is of critical importance since the effectiveness of the subsequent stages of drying and in duration depends on the quality and quantity of green pellets.This research presents the work carried out to develop model equations to predict the size distribution of pellets at any given level of intervals. Modeling of pelletization was oriented towards predicting the size distribution of pellets at any given level of variables .The prediction of pellet size distribution involves quantification of the self preserving curve and correlation between D₅₀ and the variables. A new model has been developed to predict the size distribution of the pellets using advanced statistical software “STATISTICA”. The equation Y = − 0.3757X² + 1.6256X-0.74 where “Y” is the cumulative wt.% passing and “X” is D/D₅₀ was used to predict the pellet size distribution.Correlation between D₅₀ and variables was given by “D 50” = 4.226 + (3.106*M) − (0.544*M²) + (2.044*I) − (0.644*I²) + (0.2444*T) − (0.028*T²) − (0.058*M*I) + (0.0917*I*T) using quadratic response surface methodology. The mean pellet diameter “D₅₀” observed versus predicted was compared. A polynomial regression equation was used to quantify the characteristic curve of iron ore slimes agglomeration process. This can be utilized to predict the complete agglomerate size distribution irrespective of the operating conditions and the size of the pelletizer if a relationship such as agglomerate median product size D₅₀, as a function of the operating conditions is made available.     

工艺条件对PTCR热敏陶瓷喷雾造粒粉体性能的影响

采用压力喷雾造粒的方式对BaTiO3系PTCR热敏陶瓷粉体进行喷雾造粒处理,研究了喷雾造粒过程中浆料组成和雾化条件对粉体性能的影响。研究结果表明：喷雾造粒过程中浆料粘度过高,雾化条件控制不当,都会使喷雾造粒粉体颗粒的团聚程度增加,影响粉体的松装密度和流动性,对生坯成型及材料烧结不利,考虑到料浆中粘合剂含量、固体物含量的综合影响,添加适量的分散剂可以降低料浆的粘度,控制适当的雾化压力,选用合适的喷雾直径与涡旋片组合可以获得理想的粉体。     

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。