钢球级配对铁矿石的磨矿动力学研究

以4种不同级配(m40∶m30∶m20=1∶1∶1、1∶1∶3、1∶3∶1、3∶1∶1)的钢球为研究对象,基于总体平衡模型开展磨矿动力学试验,研究了不同钢球级配对铁矿石的破碎规律,确定了5种单粒级(-13.2+9.5、-6.5+4.75、-3.35+2.36、-1.7+1.18、-0.6+0.425 mm)矿石在不同钢球级配下的比破碎速率。结果表明,铁矿石破碎规律不符合一阶磨矿动力学,比破碎速率随磨矿时间的增加而减小;级配为3∶1∶1的钢球对-13.2+9.5、-6.5+4.75 mm粒级矿石的破碎效果优于其他级配的破碎效果;级配为1∶1∶3的钢球在给料粒度大于3.35 mm时磨矿效果较差,在给料粒度小于1.7 mm时磨矿效果最好。     

磨矿介质形状对橄辉岩型钒钛磁铁矿磨矿动力学影响研究

为了更深入地研究橄辉岩型钒钛磁铁矿磨矿行为,采用钢球、钢锻作为磨矿介质在不同磨矿时间下进行了分批次磨矿试验,研究了点、线不同接触方式对橄辉岩型钒钛磁铁矿磨矿动力学过程与产品分布,重点考察了磨矿动力学参数、比破碎速率、磨矿产品分布特性。研究结果表明：两种介质下的磨矿动力学均符合标准动力学方程,相关参数k与m值均与粒径呈指数函数关系;钢锻介质更适合选择性磨矿,钢球介质下的细粒级产品较钢锻介质多,磨矿时间越大,产品分布越均匀,短时间内,钢锻介质对粗颗粒的破碎效果要优于钢球介质;以上研究结果可为橄辉岩型钒钛磁铁矿磨矿工艺参数提供一定的理论基础与参考价值。     

钢锻磨矿介质在七角井铁矿细磨中的应用#br#

七角井铁矿石属于微细粒嵌布的铁矿石，磨矿细度需达到-0.045 mm 95%左右，生产采用钢球为磨矿介质不仅磨矿效率低，而且磨矿成本高。为了提高磨矿效率，降低磨矿成本，进行了钢锻磨矿效果优越性试验，在取得较好实验室指标的情况下进行了工业应用。生产实践表明：第三段磨矿用钢锻取代钢球取得了成功，-0.026 mm粒级产率降低了5.27个百分点，+0.045 mm粒级产率降低了2.88个百分点，0.045~0.026 mm粒级效率显著提高。     

钢锻作为磨矿介质的磨矿效果研究

磨矿介质对磨矿效果有重要影响,可通过改进磨矿介质种类或形状来提高磨机的生产率以及降低选矿总成本。采用钢锻和钢球两种不同的磨矿介质进行磨矿试验,结果表明:同时磨矿3 min时,钢球磨矿-0.074 mm含量为77.72%,而钢锻磨矿-0.074 mm含量为66.18%,采用钢锻作为磨矿介质的磨矿效率略低;但是-0.038 mm含量钢锻磨矿比钢球磨矿少了15.37%。可见采用钢锻磨矿对细粒级物料有保护作用,中间粒级的物料较多。该研究在改进磨矿介质方面具有指导意义。     

球磨机中介质形状对钒钛磁铁矿破碎参数的影响研究

以0.83～2mm、0.35～0.83mm两种单一粒径的攀西钒钛磁铁矿为原料,钢球和短圆柱形钢锻为介质,设定磨矿浓度80%、磨矿时间0.5、1、2、4、6、8、10min、磨机转速96r/min,钢球的配比为D30∶D25∶D20=42∶60∶93,短圆柱钢锻配比为D30×30∶D25×25∶D20×20=28∶40∶62,介质充填率为40%。研究结果表明:不同形状的磨矿介质对钒钛磁铁矿的破碎遵循一阶动力学模型,且在短时间内短圆柱钢锻的破碎速率Si明显高于钢球的破碎速率,在短时间内介质形状对初始破碎分布参数的影响较大。     

纳米复合瓷球在钨矿石细磨中磨矿特性研究

本文以湖南某钨矿石为对象,研究纳米复合瓷球作为磨矿介质在钨矿石细磨中的磨矿特性。研究表明,纳米复合瓷球作为细磨介质可以对钨矿石进行有效破碎,实验室细磨实验可以获得新生-74μm粒级产率21.08%、新生-23μm粒级产率7.59%的磨矿产品,过粉碎现象较钢锻显著改善;在介质充填率相同情况下,纳米复合瓷球比钢锻节能69.92%;纳米复合瓷球不仅磨矿产品粒度特性更均匀且不会引入铁质污染,相同细度下,纳米复合瓷球磨矿产品浮选开路实验钨回收率比钢锻高10%左右,尾矿钨损失降低50%。本文首次将纳米复合瓷球应用于细磨作业,并获得良好效果,对以后研究具有借鉴意义。     

不同接触方式磨矿介质的钨矿磨矿动力学分析

以钢球、钢锻和六棱柱分别代表点、线、面接触方式下的磨矿介质,在不同磨矿时间条件下对钨矿进行磨矿。研究点、线、面不同接触方式下磨矿介质对硬而脆钨矿磨矿产品的影响,分析磨矿产品的筛分粒度分布特性,考察磨矿产品的均匀程度,求解磨矿动力学及比破碎速率,评估整体磨矿行为效果。结果表明,钢球的磨矿产品最不均匀,比破碎速率呈不规则变化,磨矿产品泥化严重;六棱柱的磨矿产品最均匀,破碎速率呈抛物线型,所得磨矿产品的均匀性最好,易选级别含量最多,面接触磨矿对钨矿这类脆性矿物磨矿的泥化程度减轻最为有利,可以作为新型磨矿介质在钨矿山推广应用。     

窄粒级物料磨矿最佳尺寸介质研究

采用窄粒级给料磨矿,研究了不同给料粒级对应的最佳尺寸介质。结果表明,最佳介质尺寸随给料粒度的减小而减小;最佳介质尺寸随磨矿时间的延长有增大的趋势;磨矿中存在“低效”尺寸介质,使得在所有给料条件下磨矿效率最低。     

球磨机磨矿最佳尺寸介质研究

利用实验室小型球磨机,采用窄粒级给料磨矿,研究了不同给料粒级对应的最佳尺寸介质。结果表明,最佳介质尺寸随给料粒度的减小而减小,随磨矿时间的延长有增大的趋势,磨矿中存在异常尺寸介质,使得在所有给料条件下磨矿效率最低。     

中关铁矿球磨机磨矿介质尺寸与配比试验

为确定中关铁矿选矿厂球磨机合适的磨矿介质尺寸与配比,采用段氏半理论公式计算出入磨矿石球磨机最佳磨矿介质为φ60 mm钢球和φ40 mm×50 mm、φ25 mm×20 mm钢段,并利用给料粒度相关法和等密度法,通过磨矿介质配比试验确定3种磨矿介质最佳配比为1∶1∶8;磨矿产品细度-0. 074 mm含量66. 66%,相比原矿,-0. 074 mm粒级含量提高54. 13个百分点,且能在一定程度上改善过磨问题。     

Effects of mixtures of grinding media of different shapes on milling kinetics

The effect of grinding media on milling kinetics has been generally studied using one media shape. However, very little work has been done on investigating mixtures of media shapes.Combining different grinding mechanisms in term of contacts, the volume of grinding zones can be efficiently increased when there is an optimal mixture of two or more grinding media with different shapes and, therefore the milling kinetics will be improved.A series of batch grinding tests was carried out using the same mass of spherical balls, Eclipsoids™ and cubes to break coarse, medium and fine sizes of quartz material. Then, mixtures of the same mass made of spherical balls and cubes, spherical balls and Eclipsoids™ were successively considered. The breakage parameters were determined and used to evaluate the grinding performances of the mixtures of grinding media under the same conditions.It was found that mixtures of grinding media shapes can increase the breakage rate in a particular milling environment. But, spherical balls remain the most efficient grinding media. Finally, an optimal mixture made of spherical balls and grinding media of different shapes, namely cubes and Eclipsoids that are cheaper to manufacture can be used in the grinding process alternatively to 100% balls.     

红格某选铁尾矿磨矿动力学研究

采用分批次磨矿试验,选取了-2mm粒级红格某选铁尾矿为原料,研究其在球磨机中的磨矿动力学行为,对多个窄粒级范围的磨矿产品粒度进行分析,采用MATLAB 2017软件初步建立了磨矿动力学方程,并对不同粒级磨矿速度进行了分析。研究结果表明,磨矿初期,粗粒级的磨矿速度最大,细粒级磨矿速度最小且变化幅度较小,随着时间的增加,在短时间内(1～12min),磨矿速度与参数k值呈正比例相关,在合理的介质制度下能快速磨碎粗颗粒且防止细颗粒过磨,研究此动力学过程,有助于指导尾矿选钛磨矿工艺最佳参数的选择。     

The effect of ball size on breakage rate parameter in a pilot scale ball mill

The objective of this study is to investigate the effect of ball size on grinding kinetics in a pilot scale ball mill. Six different ball media gradings were tested. Comparative tests were conducted in batch ball mill having 1.2 m diameter and 0.6 m length at constant operating condition of mill such as media mass, mill speed and input specific energy. Feed samples were ground batchwise and representative sample was taken from inside the mill for each determined grinding period. Grinding process in ball mill was modeled and the specific rate of breakage was calculated for the each test. The results indicated that the relationship between different breakage rate and particle size has a maximum for each ball size distribution. Consequently, a new equation to correlate maximum ball size and particle size at maximum breakage occurs is proposed.     

球磨机钢球球径制度对磨碎速率的影响研究

利用实验室Φ240×90锥形球磨机对-1.7+1.18 mm石灰石进行了批次磨矿试验,基于破碎速率函数与破碎分布函数的总体平衡模型讨论了钢球球径制度对磨矿速率的影响。单一球径钢球试验结果表明,大直径钢球对粗级别的磨碎速率相对较高,但对细粒级的磨碎速率衰减很快;小直径钢球对粗级别的磨碎速率较低,但对细粒级有较高的磨碎速率。采用两种球径配合的钢球制度,并以破碎分布函数作为钢球球径级配方案的依据,可综合单一球径钢球制度的优点,既保证粗粒矿石有较高的磨碎速率,又能保持对细粒级的磨碎速率衰减较慢。     

Analysis of grinding media effect on specific breakage rate function of particles in a full-scale open circuit three-compartment cement ball mill

A full-scale three-compartment FLSmidth® cement grinding ball mill with dimensions of Ø3.5 × L10 operating in open circuit was sampled to analyse the grinding media effect on specific breakage rate function of particles. Size reduction performance of the ball mill was evaluated with respect to the applied grinding media size. Samples from the circuit and inside the mill were collected. Mass balance of the circuit was done using JKSimMet Steady State Mineral Processing Simulator. Specific discharge and breakage rate functions of particles were estimated using perfect mixing modeling approach (Whiten, 1972) on the basis of the proposed open circuit three-compartment ball mill model structure (Genç and Benzer, 2015). Maximum specific breakage rate was related to maximum grinding media size in the grinding compartments. An exponential correlation was found to exist between maximum grinding media size and maximum specific breakage rate. Relationship between maximum grinding media size and maximum particle size was also fitted to an exponential function. Findings indicated that, grinding performance of cylpebs applied in the third compartment did not improved the size reduction performance as compared to the grinding performance of the first and second compartment.     

Effects of media shape on milling kinetics

Spherical balls are the dominant grinding media used in ball mills. However, balls which are initially spherical, wear into non-spherical fragments. The proportion of worn, non-spherical balls in the charge of a mill fed with 50 mm balls is dominant in ball sizes less than 30 mm. Their effects on mill performance in terms of material breakage are not yet established.The variations of specific rate of breakage with single size feed and fractional filling U, were studied for the two media shapes (spherical and worn balls). Higher breakage rates were noted with spherical media than worn balls but the differences narrow with decreasing feed size and increasing material fractional filling, U.     

Effects of grinding media shapes on load behaviour and mill power in a dry ball mill

Little attention has been given to the study of grinding media shapes and how they affect load behaviour and power draw in grinding mills. To a large extent the focus has been on how grinding media shapes affect milling kinetics in terms of specific rate of breakage and breakage distribution parameterisation.This study investigated the effects of three media shapes (cylpebs, spherical and worn balls) on load behaviour and mill power draw at various mill speeds and load filling. An inductive proximity probe was used to determine the load orientation of the grinding media charge while a load beam enabled measurement of power draw.The variations in toe and shoulder positions among media shapes were observed. This was also reflected in the power draw. The power increases to a maximum with increasing mill speed for all media shapes. The maximum power draw was reached at different mill speeds for the three studied media shapes.     

Understanding fine ore breakage in a laboratory scale ball mill using DEM

DEM models of fine grinding in ball and stirred mills have to date almost entirely focused on the motion of the media and their interaction with the mill configuration. For SAG mills, a large fraction of the feed material can now be accurately represented in DEM models. However, for other mill types with much finer feed materials, such as the second chamber of a cement ball mill, the vast numbers of feed particles makes their explicit inclusion in the models prohibitive. However, it is now feasible to model a periodic section of a laboratory scale ball mill and include the coarser end of the ore size distribution directly in the DEM model. This provides the opportunity to better understand the effect of media on the interstitial bed of powder and of the effect of the powder on the media. The effect of the powder fill level, which is varied between 0% and 150% of the pore space in the media charge, is explored. The distribution of the powder, its effect on power draw and the way in which it contributes to the pattern of energy utilisation is assessed. The simulation results are compared with experimental results from a test at similar ball loading and rotation rate and for several size fractions of ore at a range of powder fill fractions. Tracking the collision histories of specific ore particles within the charge allows estimates of the probability (per unit time) of collision between media and ore particles (the “Selection” function) and of the intensity of each collision which can be used to estimate the severity of breakage using the JKMRC breakage model (the “Breakage” function). The energy spectra indicate that for a typical ore, only very few collisions are large enough to cause damage to the body of each particle. This provides an estimate of the energy efficiency which is less than 10% at even the best operating conditions.     

A multiscale method for including fine particle effects in DEM models of grinding mills

A multiscale model for including interstitial powder or fine particles in DEM simulations of grinding mills is proposed. This consists of a traditional DEM model at the macroscale which includes only grinding media and potential coarser fractions of feed and product. Microscale models are embedded within this macroscale model. These can be sufficiently small that the fine powder can be included in a computationally affordable manner. The direct inclusion of the fine particles in the model allows predictions to be made of the effect of the local grinding environment on these fine particles. A shear cell is a good choice for the microscale model as it can well represent the local flow conditions at different points within the mill macroscale model. Averaging the macroscale flow allows the local collisional environments to be characterised and provides estimates of the shear rate and normal stress at each of the microscale locations which then controls the configuration of each microscale shear cell. A 1-way coupled implementation of this multiscale model is demonstrated for a simple cement ball mill. The relative importance of each region of the flow is determined with the toe region being the dominant contributor to the grinding. The grinding action produced by the shearing of thin layers of powder between adjacent layers of media flowing over each other is clearly demonstrated by the behaviour predicted in the microscale models. Methods for calculating power draw that include the effect of powder and for constructing collision energy spectra for the powder are described. Finally, the importance of the cushioning effect of high powder loads on the flow behaviour of the media is demonstrated.