Effects of particle characteristics on the granulation ability of iron ores during the sintering process

The granulation behavior of iron ores is essential for subsequent parameter optimization and efficient granulation, especially under changing material conditions. In this study, the effects of surface properties and particle size were analyzed using a laboratory granulation method; an estimation of the granulation of sintering blends was subsequently conducted for the base ores. Circularity and porosity were observed to negatively affect the granulation of iron ores, whereas wettability positively affected the granulation and was the most influential factor, indicating that wetting of iron ores is desirable during granulation. When iron ores with complex size distributions were granulated, the equivalent surface area was the main influencing factor for coarse particles larger than 1 mm and the ratio of adhering fines to intermediates was the main factor for fine particles smaller than 1 mm. By combining the granulation of coarse and fine particles with their proportioning, we proposed a calculation method for estimating the granulation ability of sintering blends. Good verification was demonstrated with the designed schemes. The results suggest that the developed method is effective for predicting the granulation of iron ore mixtures.     

矿石颗粒尺度分布的双圆算法

针对高炉内矿石颗粒外形不规则和边缘暗淡模糊等特性，提出了双圆比的概念，运用图像预处理、彩色形态学平滑、颗粒点定位、颗粒最大区域扩张、双圆尺度检测等方法，能够很好地对矿石颗粒尺度分布情况进行检测.对比实验表明，该算法比经典算法具有更高的准确度.     

采场环境中硫化矿石氧化自热的影响因素

 堆积在采场环境中的硫化矿石容易发生氧化自热,从而造成环境污染、导致矿石结块,甚至引发矿山内因火灾事故。系统阐述了硫化矿物的晶体结构、痕量元素的含量、环境温度、铁离子、氧气浓度、空气湿度、矿石含水率、矿样的粒度分布、环境的pH值、微生物等主要因素对采场中硫化矿石氧化自热的影响。结果表明,硫化矿石在低温环境中的反应模式非常复杂,其氧化自热受诸多因素共同影响;较高的环境温度和氧气浓度有利于矿石氧化,矿样粒度越小越容易自热,铁离子与细菌对硫化矿石的氧化具有催化作用,水对矿石的氧化自热具有催化和阻化两重作用,而晶体结构、痕量元素含量的影响均表现出不确定性。     

铁矿石固态还原过程中吸硫的反应动力学

研究了铁矿石固态还原条件下，矿石吸硫动力学．用电子探针（ＥＰＭＡ）研究了硫在矿内的分布．结果表明，硫化氢与矿内金属铁的界面反应为吸硫反应的限制步骤．     

北京明长城青砖毛细吸水性测定及其影响因素

长城是著名的世界文化遗产。近年来北京市文物局提出了长城文化带保护建设工作,且因水作为多孔材料青砖耐久性能的主要影响因素,其携带的侵蚀性介质会对青砖造成严重破坏,故需对长城主要承重材料-青砖的毛细吸水性进行研究。通过单面吸水法和卡斯特瓶法分别检测青砖的毛细吸水系数,发现卡斯特瓶法误差主要来源于水压影响和读数延迟;研究并建立了两种检测方法测试结果的关系方程或比例系数,可应用于不可取样长城青砖现场测试的毛细吸水系数转换为实际的毛细吸水系数的推算工作。此外,分析评估了环境温度、初始含水率、孔隙率和孔径4个主要因素对青砖毛细吸水性的影响,发现温度、孔隙率及孔径对毛细吸水性影响较大;且呈正相关关系,初始含水率则影响不大。     

硼铁矿石固相还原动力学

用热重法研究了硼铁矿石氢气还原动力学。氢气流量600ml/min,温度600～1000℃。实验结果表明,矿石结构、孔隙度和颗粒的大小对还原率有明显的影响。单一方向还原实验表明,气体在产物层孔隙的扩散对还原速度影响显著,是还原的控制步骤。将实验数据用TURK-DOGAN内扩散速度方程处理,求出H_2-H_2O气体在产物层孔隙中有效扩散系数D_o值随还原温度下降而明显减小。     

De Broglie wavelength of a non-local four-photon state

Superposition is one of the most distinctive features of quantum theory and has been demonstrated in numerous single-particle interference experiments. Quantum entanglement, the coherent superposition of states in multi-particle systems, yields more complex phenomena. One important type of multi-particle experiment uses path-entangled number states, which exhibit pure higher-order interference and the potential for applications in metrology and imaging; these include quantum interferometry and spectroscopy with phase sensitivity at the Heisenberg limit, or quantum lithography beyond the classical diffraction limit. It has been generally understood that in optical implementations of such schemes, lower-order interference effects always decrease the overall performance at higher particle numbers. Such experiments have therefore been limited to two photons. Here we overcome this limitation, demonstrating a four-photon interferometer based on linear optics. We observe interference fringes with a periodicity of one-quarter of the single-photon wavelength, confirming the presence of a four-particle mode-entangled state. We anticipate that this scheme should be extendable to arbitrary photon numbers, holding promise for realizable applications with entanglement-enhanced performance.     

初始含水量及冻融循环对黄土微结构的影响

冻融循环作用是季节性冻土地区工程病害发生的主要致灾因子。在冻融循环作用下,土体结构性逐渐丧失、强度不断劣化,最终导致灾害的发生。以延安市延安新区黄土为研究对象,配置不同初始含水量试样,经历0、1、3、6、10、15次冻融循环,通过SIGMA500扫描电子显微镜观察试样微观结构的演化规律。试验结果表明:随着冻融循环次数的增加,试样内部裂纹、裂缝不断发育演化,水分迁移通道不断扩展;初始含水量高的试样裂纹裂缝发育演化越明显;冻融循环作用使得试样内部大颗粒分解为若干小颗粒、颗粒表面的棱角不断磨圆、表面起伏不断减小;当冻融循环10次以后,颗粒大小、颗粒形状、表面起伏趋于稳定,试样颗粒尺寸趋于统一,试样大孔隙减小,小空隙增多,总体孔隙率增大。试样颗粒间的胶结强度随着冻融循环次数的增加不断减小,破碎作用产生的小颗粒造成粒间的接触点增多,致使试样的内摩擦角增大。     

Deposition behavior of multi-particle impact in cold spraying process

In the practical cold-spraying process, a number of particles impact onto a substrate and then form a coating. To study the deformation behavior and multi-particle interactions, single-particle, two-particle, and three-particle impacts were simulated using the AN-SYS/LS-DYNA version 970. A copper coating was prepared and scanning electron microscopy (SEM) was employed to analyze the microstructures of the powders and the coating. Numerical results reveal that the critical deposition velocity is 600 m/s for a copper particle/copper substrate. The particles deform more fully due to multi-particle interactions, such as tamping, interlocking, and extrusion effects. The compression ratio increases from 40% to 70% as a result of the tamping effect. This is beneficial for achieving the cold-sprayed coating. The multi-particle morphology and compression ratio in the experiment are consistent with those of simulation results. Based on these results, the coating of high performance can be prepared through selecting appropriate parameters and suitable pre-treatment processes.     

含钴矿石摇瓶生物浸出比较试验的研究

对含钴矿石进行了工艺矿物学研究,明确了该含钴矿石的主要化学成分、粒度分布、矿物组成与嵌布特征.研究表明,硫化矿物主要为硫铜钴矿、黄铜矿、斑铜矿、辉铜矿、铜蓝、黄铁矿等.硫铜钴矿大多数以单体形式赋存,还有一部分为连生体.该含钴矿石含钴163%,铜105%,铁124%,硫1500%.用实验室驯化培养的具有良好抗钴性能的ZY101菌种对此含钴矿石进行摇瓶浸出实验研究,浸出结果表明:利用优良菌种浸出,钴浸出率达8571%.对比生物法与非生物的高铁溶液浸出,生物法钴浸出率提高6326%,耐钴ZY101浸矿菌浸钴效果显著.     

超声波强化均匀沉淀法制备纳米TiO2

为了改善纳米TiO2的分散性能和细化其颗粒尺寸,采用超声波强化均匀沉淀法制备纳米TiO2.首先以工业级硫酸氧钛为原料,用均匀沉淀法制备纳米TiO2,通过对比试验来反映超声波对于制备纳米TiO2的影响.然后采用BET比表面积与孔隙度分析、扫描电子显微镜、透射电子显微镜、X射线衍射分析研究了超声波的强化作用.试验结果表明:超声波的强化作用具有明显的细化颗粒尺寸的作用;能增加纳米TiO2的比表面积、孔容积与孔径;能改善分散度,使颗粒粒径分布范围变窄.通过均匀沉淀过程能直接获得纯锐钛型纳米TiO2,而无需经过特定温度的煅烧定型,超声波作用对产物晶型无影响.     

基于差示扫描量热法的哈尔滨黏土未冻水含量特性

为研究哈尔滨黏土在低温条件下冻土中未冻水含量特性,通过差式扫描量热法(differential scanning calorimetry, DSC)研究了不同初始含水量的哈尔滨本地黏土、高岭土和蒙脱土在冻结过程中的未冻水含量变化,并结合微观角度的扫描电子显微镜(scanning electron microscope, SEM)实验、中观角度的液塑限实验对不同黏土颗粒土质以及哈尔滨黏土粒度进行实验研究。结果表明,温度因素对于未冻水含量变化的影响最为显著,可将未冻水含量的变化过程依据节点温度分为3个典型阶段,分别为恒定不变段、剧烈下降段和缓慢降低段。初始含水量主要影响冻结过程第二阶段,初始含水量越高,第二阶段冻结的水量越多。土质不同,其未冻水变化曲线不同。粒度分布主要影响冻结过程的第三阶段,粒径越小,等效微小孔隙越多,第三阶段未冻水含量变化相对更剧烈。可见哈尔滨黏土的冻结过程中的未冻水含量特性除了与初始含水量和温度有着密切联系,同时也受到土体的土质、粒度的影响。     

微细粒混合磁选精矿分级—分散浮选试验研究

针对东鞍山混合磁选精矿进行了预先分级—强化分散浮选试验研究，同时结合沉降试验、动电位测试、浊度测试等分析了分选效果改善的原因.在最优条件下分级—分散浮选闭路试验可获得精矿铁品位66.24%、铁回收率79.47%的浮选指标，与单一分散浮选的闭路试验相比，精矿铁回收率提高了4.47%.沉降试验和浊度测试表明，分散剂柠檬酸及粒度组成均会影响赤铁矿-石英混合矿的分散特性，柠檬酸主要吸附在赤铁矿表面从而增大矿粒间的静电斥力，优化粒度组成实现窄级别浮选则会进一步减弱矿粒间的非选择性团聚(罩盖)，为后续浮选分离创造有利条件，这也与DLVO理论及团聚动力学的分析结果基本一致.     

不同粒径水性聚氨酯乳液的制备与性能研究

以异佛尔酮二异氰酸酯（IPDI）、聚（1,6-己二醇/新戊二醇-己二酸）（PHNA）,1,4-丁二醇（BDO）、2,2-二羟甲基丙酸（DMPA）为主要原料、三乙胺（TEA）为中和剂,乙二胺（EDA）为后扩链剂,利用两种乳化方法和不同的DMPA用量制备了不同粒径的羧酸型水性聚氨酯乳液,使用动态光散射法测量其粒径和粒径分布,并测量了吸水率、拉伸强度、断裂伸长率、光泽度等性能.结果表明:制备的乳液粒径最小40 nm,最高340 nm,粒径分散系数（PDI）处于0.07~0.26之间,两种乳化工艺的粒径与粒径分布有明显差异;随着粒径的变化胶膜拉伸强度最高49.62 MPa,对应的断裂伸长率为922%,吸水率最低为5.25%,光泽度最高87.8°;粒径及粒径分布对吸水率、拉伸强度、光泽度等有重要影响,而对断裂伸长率影响不大.      

基于模型试验的散装铁精矿流态化细观规律

利用室内振动台模型试验,对散装铁精矿流态化细观规律进行了研究.基于细观图像采集分析系统,研究了铁精矿在流态化演化过程中颗粒间及颗粒与水分间的相互作用,分析了颗粒长轴方向、平均接触数、平面孔隙率等演化规律,探讨了铁精矿流态化细观规律及其与宏观现象间的联系.结果表明:水分迁移在铁精矿流态化演化过程中至关重要,其宏观表现是水液面上升;细观组构是控制铁精矿宏观力学行为的重要参数,其所反映的规律与宏观现象一致.     

不同孔隙比下风化壳淋积型稀土矿强度特性

风化壳淋积型稀土开采过程中,孔隙比为影响浸矿效果和矿体稳定性的关键因素.为探索不同孔隙比下风化壳淋积型稀土矿强度特性变化,选取6组重配比的稀土矿样,对不同孔隙比矿样进行了直接剪切实验,探讨孔隙演化对矿体抗剪强度的作用规律,揭示孔隙比对黏聚力和内摩擦角的影响机制.研究表明:不同孔隙比非饱和稀土矿对应着不同的剪切强度,基于试验数据发现剪应力与剪位移呈"类抛物线"变化,并建立了孔隙比与抗剪强度指标的关系模型.机制分析认为,随着孔隙比的增大,结合水膜效应逐渐弱化,粒间接触点数目也随之减少,使矿体抗剪强度减小.     

Application of a water cooling treatment and its effect on coal-based reduction of high-chromium vanadium and titanium iron ore

A water cooling treatment was applied in the coal-based reduction of high-chromium vanadium and titanium (V–Ti–Cr) iron ore from the Hongge region of Panzhihua, China. Its effects on the metallization ratio (η), S removal ratio (R_S), and P removal ratio (R_P) were studied and analyzed on the basis of chemical composition determined via inductively coupled plasma optical emission spectroscopy. The metallic iron particle size and the element distribution of Fe, V, Cr, and Ti in a reduced briquette after water cooling treatment at 1350°C were determined and observed via scanning electron microscopy. The results show that the water cooling treatment improved the η, R_S, and R_P in the coal-based reduction of V–Ti–Cr iron ore compared to those obtained with a furnace cooling treatment. Meanwhile, the particle size of metallic iron obtained via the water cooling treatment was smaller than that of metallic iron obtained via the furnace cooling treatment; however, the particle size reached 70 μm at 1350°C, which is substantially larger than the minimum particle size required (20 μm) for magnetic separation. Therefore, the water cooling treatment described in this work is a good method for improving the quality of metallic iron in coal-based reduction and it could be applied in the coal-based reduction of V–Ti–Cr iron ore followed by magnetic separation.     

悬浮态乳液聚合制备疏松多孔型丙烯腈/丙烯酸甲酯共聚物

以水为分散相,丙烯腈（AN）和丙烯酸甲酯（MA）为连续相,聚乙烯醇（PVA）为分散剂,采用悬浮态乳液聚合工艺合成了疏松多孔型丙烯腈/丙烯酸甲酯共聚物.用扫描电镜、激光衍射粒度分析仪、比表面积及孔隙度分析仪对共聚物的形态、粒径大小及分布进行了表征.系统研究了引发剂浓度、温度、水油比、分散剂用量等条件对共聚物形态与结构的影响.结果表明：随引发剂浓度的增加和温度的升高,聚合物粒径分布变宽;低的引发剂浓度对孔径分布的影响较小,但当引发剂浓度进一步升高时,虽然孔径分布并没有显著改变,但孔体积迅速增大;孔径分布随温度和水油比的升高变化并不明显.悬浮态乳液聚合工艺制得的AN/MA共聚物粒径为10—500μm.     

LiCoO2的形貌与结构对其电化学性能的影响

研究了对电极界面状态有重要影响的LiCoO2物理参数如粒径分布、比表面积及表面形貌等对LiCoO2电化学性能的影响.研究结果表明:粒径及比表面积对LiCoO2电极的容量循环稳定性及电压循环稳定性有较大的影响;适宜的粒径分布有助于提高LiCoO2电极的循环稳定性,过大的比表面积会使电极循环稳定性急剧下降;随着晶块尺寸的减小,LiCoO2材料在大电流下的放电性能得到改善;在优化条件下合成的LiCoO2样品具有最佳的高倍率性能、较高的容量及电压循环稳定性.     

ADDP改性纳米碳酸钙及其在PP塑料中的应用

用磷酸酯表面活性剂改性纳米碳酸钙，测定了改性前后CaCO3吸油率、接触角、糊粘度、粒径分布的变化情况；考察了聚丙烯中不同的CaCO3填充量对塑料的冲击韧性、断裂伸长率、拉伸强度等性能的影响．结果表明：CaCO3改性后吸油率降低，与水的接触角增大，糊粘度减小，分散粒径变小；改性CaCO3的增加提高了聚丙烯的冲击韧性和拉伸强度。