聚磁介质的磁感应特性及其磁力分选行为研究

发布时间：2018-09-10 17:38

【摘要】：本文针对目前高梯度强磁选设备的工业应用现状,分析了不同类型聚磁介质工业应用中存在的优势与不足,设计了一种用于强化细粒级弱磁性铁矿物回收的强磁选用聚磁介质,借助于有限元仿真模拟对单一介质体及复合介质体交互作用体系下的磁场特性进行了数值分析,详细地考查了镜铁矿单矿物在介质表面的磁吸附率及几种赤铁矿矿石的高梯度分选效果,系统地验证了数值模拟对物料分选行为的预测规律,从而确定了凸极介质的最佳参数。通过采用X射线衍射分析、化学分析、铁物相分析及显微镜下查定等多种分析检测手段,对不同粒级镜铁矿单矿物开展了矿物种类的查定、铁含量的测定、含铁的矿物类型的确定及相应铁分布率的标定等工作,结果表明：镜铁矿单矿物试样中铁矿物主要为α-赤铁矿,其铁分布率占所有含铁矿物量的99%,粒度较粗的物料中赤铁矿的矿物含量相对较低,并查明了各粒级单矿物中铁矿物的解离状态。通过化学分析、粒度筛析、铁物相分析等检测手段,对宝钢集团梅山矿业公司选矿厂强磁扫选尾矿、东鞍山烧结厂强磁给矿及强磁尾矿、海南石碌铁尾矿等多种矿石的物料性质进行了查定,弄清了物料的粒度分布情况、不同粒级铁的分布率、铁矿物的存在类型及相对含量,结果表明：几种弱磁性铁矿石试样中主要含铁矿物均为赤铁矿,原矿物料粒度小于0.043mm的粒级均占80%以上,说明几种弱磁性铁矿石中待回收铁矿物均为赤铁矿且集中于细粒级物料中。采用Ansoft三维磁场模拟技术对辅助凸极聚磁介质的单一介质体及多介质体复合体系的磁场特性进行仿真研究,探明了介质体表面辅助凸极的尖端形状、角度、凸极间距等结构参数对单元介质体周围磁场分布的影响规律,揭示了多介质体复合体系介质间感应磁场的交互影响机制,预测了不同介质的磁场特性对分选过程产生的可能影响,研究结果表明：凸极介质较之等径圆棒介质在介质表面磁感应强度和磁场不均匀程度上均有提高,尤其在背景磁感应强度较低时这种情况更为突出；凸极尖角过大或过小均不利于分选,确定适宜凸极尖角角度为60。：在凸极间距为2mm或4mm时,尖端高磁感应强度和凹部低磁感应强度交替出现的频率高,沿介质体轴向介质表面磁场的不均匀程度提高,预测分选效果较好；相邻介质中心距越小,介质间的磁感应云叠加效果越显著,介质表面凸极尖端及周围空隙的磁感应强度越大,随介质中心距增大,介质表面磁感应强度逐渐减弱,但中心距增大到一定程度时,介质间的磁感应交互影响已弱化且等同于单一介质体时的磁感应分布。在水平磁场和垂直磁场下分别进行了印度细粒赤铁矿、广东英德褐铁矿强磁尾矿及宝钢集团梅山矿业公司选矿厂强磁扫选尾矿的不同介质的分选试验,初步明确了凸极介质体表面凸极棱角突出强化了磁场梯度作用,进而增强介质对磁性矿物颗粒的磁力作用,可提高铁精矿回收率,通过探索试验证实了改变介质表面结构特征是强化磁场梯度作用进而增大磁场力的有效途径。在一定范围内较大棒径的介质可通过适当降低棒(丝)间隙及提高介质充填率的方式取得与较小介质相当的分选效果。此外,较大棒径的介质虽表面磁感应强度较高,但介质表面积减小,有效吸附磁性物面积降低；棒径小的介质磁场梯度较大,介质表面积大,但充填率降低,磁损耗增加,因此针对不同待分选物料应确定适宜分选的介质棒径与充填率。通过不同粒级镜铁矿单矿物的磁吸附试验,考察了凸极介质的排布方式、脉动水流作用对不同粒级单矿物磁吸附行为的影响,揭示了介质参数对弱磁性单矿物的捕获行为,找出了粒度特征对单矿物磁吸附作用体系的作用机制,验证了三维磁场模拟的预测结果,研究结果表明：交错排列的介质对镜铁矿单矿物的磁吸附率高于平行排列介质的相应值,当给料粒度减小时,交错排列与平行排列介质磁性物吸附率的差值逐渐增大；增加脉动作用(脉动冲程为11.4mm,冲次为150次/min)较之无脉动作用时,相同间隙的不同凸极间距介质对物料的磁性物吸附效果差异性更明显；凸极间距为1.Omm时的凸极介质的磁性物吸附能力最佳。在相同间隙下,凸极介质较之光滑圆棒介质对镜铁矿单矿物的磁力作用更大,回收率更高。通过对东鞍山强磁给矿、东鞍山强磁尾矿、海南石碌铁尾矿开展系统的磁分离试验,详细考察了介质结构参数变化对分选效果产生的差异性,确定了适宜强化弱磁性细粒铁矿物颗粒回收的聚磁介质结构参数,分析了介质对弱磁性物料的分选行为,揭示了介质结构参数与介质体系特征参数对磁性产物粒度分布的作用规律等问题,并对凸极介质和圆棒介质的在相同背景磁场强度下的指标进行了对比,研究结果表明：凸极间距为1.Omm,介质体间隙为3mm的介质参数对东鞍山强磁给矿的分选效果最好；凸极间距为0.5mm,介质体间隙为2mm的介质参数对东鞍山强磁尾矿和海南石碌铁尾矿的分选效果最好；凸极介质较之圆棒介质,其磁性产物粒度回收下限有所降低,同时其回收率的提高主要源自细粒级颗粒的回收,达到了强化细粒级弱磁性矿物回收的目的。凸极介质与圆棒介质达到相同磁性产物回收率的情况下,凸极介质所需的背景磁感应强度平均低于圆棒介质背景磁感应强度约0.2T,为强磁选设备的节能降耗起到较大的作用。本文的研究成果为强化弱磁性铁矿物颗粒的强磁选回收提供了新的技术思路,为聚磁介质的开发与改进奠定了理论基础,同时也为改善高梯度强磁选处理难选铁矿资源的技术指标提供重要的技术积累。
[Abstract]:Aiming at the present industrial application situation of high gradient high intensity magnetic separation equipment, this paper analyzes the advantages and disadvantages of different types of magnetic concentrating media in industrial application, designs a kind of magnetic concentrating medium which is used to enhance the recovery of fine-grained weak magnetic iron ore, and uses finite element simulation to simulate the interaction between single medium and composite medium. The magnetic field characteristics under the action system are numerically analyzed. The magnetic adsorption rate of the single mineral on the surface of the medium and the high gradient separation effect of several hematite ores are examined in detail. The prediction law of the material separation behavior by numerical simulation is systematically verified, and the optimum parameters of the salient medium are determined. By means of radiation analysis, chemical analysis, iron phase analysis and microscopic examination, the determination of mineral types, iron content, types of iron-bearing minerals and the calibration of corresponding iron distribution rate of single mineral specimens of Specularite with different grain sizes were carried out. As a kind of alpha-hematite, its iron distribution rate accounts for 99% of all iron-bearing minerals, and the mineral content of hematite in coarse-grained materials is relatively low. The dissociation state of iron ore in single mineral of each grain size has been found out. The material properties of tailings, high-intensity magnetic tailings and high-intensity magnetic tailings from Donganshan Sintering Plant, and Shilu iron tailings from Hainan Province were investigated. The particle size distribution, distribution rate of iron with different grain sizes, existing types and relative contents of iron ores were found out. The results show that the main iron minerals in the samples of several weak-magnetic iron ores are iron ores. In hematite, the particle size of raw material is less than 0.043 mm, accounting for more than 80%, indicating that the iron ore to be recovered from several weak magnetic iron ores is hematite and concentrated in fine-grained materials. The influence of structure parameters such as tip shape, angle, salient spacing and so on on magnetic field distribution around the unit dielectric body is studied. The interaction mechanism of induced magnetic field between the media of multi-dielectric composite system is revealed. The possible influence of magnetic field characteristics of different media on the separation process is predicted. The results show that the magnetic induction intensity and the magnetic field inhomogeneity of the salient medium are higher than that of the equal-diameter rod medium, especially when the background magnetic induction intensity is lower; too large or too small salient tip angle is not conducive to sorting, and the suitable salient tip angle is 60. At 4mm, the frequency of alternating high magnetic induction intensity at the tip and low magnetic induction intensity at the concave is high, and the magnetic field inhomogeneity along the axial direction of the dielectric surface is improved, and the predictive sorting effect is better; the smaller the center distance between adjacent media, the more remarkable the magnetic induction cloud superposition effect between the media, and the magnetic induction intensity at the salient tip and the surrounding gap of the dielectric surface. With the increase of the center distance, the magnetic induction intensity on the surface of the medium decreases gradually, but when the center distance increases to a certain extent, the magnetic induction interaction between the media has weakened and is equivalent to the distribution of magnetic induction in a single medium. Magnetic tailings and separation tests of different media for high intensity magnetic sweeping tailings in Meishan Mining Company of Baosteel Group have been made clear preliminarily that the prominence of the prominent edges and corners on the surface of the prominent medium strengthens the magnetic field gradient effect, and then enhances the magnetic force of the medium on the magnetic mineral particles, which can improve the recovery of iron concentrate. The experimental results show that the change of the magnetic gradient on the surface of the prom The surface structure of the medium is an effective way to strengthen the magnetic field gradient and increase the magnetic field force. In a certain range, the medium with larger rod diameter can achieve the same separation effect as the medium with smaller diameter by reducing the gap between rods and wires and increasing the filling rate of the medium. However, the surface area of medium decreases with the decrease of the surface area of medium, and the magnetic field gradient of medium with small rod diameter is larger than that of medium with large surface area, but the filling rate decreases and the magnetic loss increases. Therefore, the suitable diameter and filling rate of medium rod should be determined according to different materials to be sorted. The distribution of salient medium and the effect of pulsating flow on the magnetic adsorption behavior of single mineral with different particle size have been studied. The trapping behavior of medium parameters on weak magnetic single mineral has been revealed. The mechanism of particle size characteristics on the magnetic adsorption system of single mineral has been found. The predicted results of three-dimensional magnetic field simulation have been verified. The magnetic adsorption rate of the medium to the single mineral of Specularite is higher than that of the parallel arrangement medium, and the difference between the magnetic adsorption rate of the staggered arrangement and the parallel arrangement medium increases gradually when the feed particle size decreases, while the pulse action (the pulse stroke is 11.4 mm and the pulse time is 150 times/min) is higher than that of the non-pulse action. The magnetic properties of the salient medium with 1.Omm salient pole spacing are the best. At the same gap, the salient medium has more magnetic effect on the single mineral of Specularite and higher recovery than the smooth rod medium. A systematic magnetic separation experiment was carried out in Shilu iron tailings of Hainan Province. The difference of separation effect caused by the change of medium structure parameters was investigated in detail. The structure parameters of magnetic concentrate suitable for strengthening the recovery of weak magnetic fine iron ore particles were determined. The separation behavior of medium for weak magnetic materials was analyzed. The medium structure parameters and medium bodies were revealed. The results show that the medium parameters with 1.Omm salient interval and 3 mm medium interval have the best separating effect on Donganshan high-intensity magnetic feeding ore. 0.5mm, 2 mm interval of medium medium parameters on the Donganshan strong magnetic tailings and Hainan Shilu iron tailings separation effect is the best; salient medium than the round rod medium, the magnetic product size recovery lower limit has been reduced, and its recovery rate mainly from the recovery of fine particles, to strengthen the fine-grained weak magnetic mineral return. The average background magnetic induction intensity of salient medium is lower than that of round medium about 0.2T under the condition that salient medium and round rod medium achieve the same recovery rate of magnetic products, which plays an important role in saving energy and reducing consumption of strong magnetic separation equipment. It provides a new technological idea for separation and recovery, lays a theoretical foundation for the development and improvement of magnetic concentrating medium, and also provides an important technical accumulation for improving the technical index of high gradient high intensity magnetic separation for refractory iron ore resources.
【学位授予单位】：东北大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TD924;TD951

【参考文献】