电功率法测定磨矿功率的研究

在磨矿过程中,磨机拖动电机的输入功率可分为三部分:①带动磨矿介质和物料一起运动的磨机筒体运转所需的功率,即有用功率;②克服空心轴颈与轴承之间的磨擦及传动装置的阻力所需的功率;③电机损耗功率。提高磨矿效率的实质在于提高磨机的有用功率,使磨矿介质从外界获得尽可能高的能量,并释放出来,最大限度地用于粉碎物料上。因此,磨机有用功率的研究长期以来一直为人们所重视,而对磨矿功耗进行测定则是该领域内研究     

回声状态网络在半自磨机功率预测中的应用

采用回声状态网络(ESN)对半自磨机功率进行了预测, 并成功应用于某现场半自磨机的功率预测中。与实时监测结果对比发现, 该算法对磨机功率预测具有较高的鲁棒性和准确性, 同时能结合选矿厂实际情况, 具有较好的实用性和广泛性。该方法不仅可用于磨矿过程磨机的自动化控制, 同时可在现场检测仪表出现故障时为现场磨机控制提供必要的参数指导。采用ESN回声状态网络对半自磨机功率进行预测可提高半自磨机磨矿效率、防止磨机涨肚、降低球耗及电耗。     

基于离散元的螺旋立式磨机启动功率研究

依据北方重工西沙盖德MLL355型螺旋立式磨机实际参数,利用EDEM软件,建立了螺旋立式磨机模型,并进行了不同填充率和启动时间下启动峰值功率与平均功率的分析。结果表明,填充率对启动功率有着很大的影响,在填充率为60%~70%时,随着填充率的增加,磨机启动功率有着显著的增加;在填充率为70%~80%时,磨机启动功率相差不大,但平均运行功率随着填充率的增加而增加。磨机启动完全后,平均运行功率约为峰值功率的0.58~0.7。随着启动时间的延长,启动功率明显降低,因此采用变频系统除可工艺调整之外,还可以保护主要部件在启动中不受损伤。     

基于DEM的大型半自磨机操作参数研究

通过离散元数值模拟方法对大型半自磨机进行了仿真模拟,研究了转速率,填充率,钢球直径对衬板磨损厚度、法向与切向累积接触能量、磨机有效功率的影响。通过模拟结果分析发现发现磨机有效功率随着磨机转速的增大呈先增大后趋于平缓的趋势,填充率为25%时的法向累积接触能量明显高于其他填充率,衬板磨损程度最大,而钢球直径对磨机的有效功率影响不明显,直径为125mm时衬板的磨损程度最高。     

立式预磨机工作参数对其功率影响的试验研究

使用四因素五水平的正交设计方案,并利用数据拟合的方法,建立了立式预磨机功率消耗的数学模型,分析了单因素对立式预磨机功率的影响规律,为立式预磨机进一步的研究与应用打下了基础。     

振动磨机有用功率计算的试验研究

通过对振动磨机运动特点及简化模型的分析,探讨了冲击和正向挤压是振动磨机主要的碎矿方式。在此基础上,运用动力学有关理论,建立了振动磨机有用功率计算的表达式,并通过试验进行验证。结果表明:振动磨机有用功率计算值与试验结果基本相符。     

基于离散元法的半自磨机磨矿过程的仿真研究

通过离散元软件EDEM建立了半自磨机仿真试验模型,并对其磨矿过程进行了模拟,分析了不同转速、衬板个数及衬板高度对半自磨机有效功率的影响。结果表明,随着转速率和衬板的增加,半自磨机的有效功率成线性增加;不同衬板高度对半自磨机有效功率的影响不同;随着L/H的变化,半自磨机的有效功率不断变化,在L/H=5左右,半自磨机的有效功率趋于最大值。可为半自磨机运行参数的选择提供一定的参考依据。     

磨机驱动功率的计算

对球磨机运转所需要的驱动功率和有用功率进行分析，建立了数学模型和计算方法。并把磨机驱动功率的计算值和实测值进行比较，说明改进磨机的传统设计方案是实现磨机节能的有效途径。     

自磨机的结构设计与分析

三十多年来,随着自磨技术的不断发展,自磨机的结构也日趋完善,而且向大型化发展。但是自磨机的结构却因工作要求的不同而异。本文就干式、湿式自磨机的主要结构作以介绍,全文分三部分:第一部分介绍自磨机筒体;第二部分介绍传动装置;第三部分介绍主轴承。     

研磨体在瀑布工作状态下磨机所需功率的研究

通过研究倾斜隔仓板磨机中研磨体在瀑工作状态下的质量变化,得到了相应条件下磨机所需功率的计算公式,为确定磨机总传动功率提共了必要的依据。     

Experimental analysis of wet mill load based on vibration signals of laboratory-scale ball mill shell

Real-time measurement of the mill load is the key to improve the production capacity and energy efficiency for the grinding process. In this paper, experimental analysis of the wet mill load based on the vibration signals of the laboratory-scale ball mill shell is presented. A series of experiments are conducted to investigate the vibration characteristics corresponding to different grinding conditions such as dry grinding, wet grinding and water grinding. The power spectral density of the vibration signals is systematically interpreted.Experimental results show that the rheological properties of the pulp affect the amplitude and frequency of the vibration signal. The most important conclusion is that the frequency range of the shell vibration of the laboratory wet mill can be divided into three parts, namely natural frequency band, main impact frequency band and secondary impact frequency band. Finally, soft-sensor models between vibration signal and mill operating parameters of mill load are established using genetic algorithm-partial least square (GA-PLS) technology. After more work on industry scale ball mill is done, the soft-sensor modeling based on the mill shell vibration for operating parameters of mill load will improve the performance of the ball mill in the grinding process.     

球磨机的动态建模研究

磨矿分级流程模拟仿真系统可实现各种操作条件下的产品粒度在线检测,为操作参数优化提供指导,而球磨机是磨矿分级回路的重要设备单元,因此球磨机的数学模型是该流程仿真系统的基础。借助磨矿动力学与物料平衡有关理论,分析现场实际运行参数与磨机功耗的关系,通过引入选择函数建立球磨机的动态数学模型,基于灰盒神经网络理论建立了磨机功耗预测模型,并利用Matlab的Simulink组件建立了仿真模型,对所建模型进行仿真分析。模型的效验与扰动试验验证了所建模型的有效性与合理性。     

Experimental observations of lifter parameters and mill operation on power draw and liner impact loading

In mineral processing the mill power plays a major role in the economics of the process and is a critical design criterion. The mill power is influenced by a range of parameters such as: charge and slurry filling, number and geometry of lifters, and mill speed. Deriving the optimum conditions of these parameters should lead to efficient mill operation. Additionally, the optimum utilization of the impact loads that are affected by charge and slurry filling, number of lifters, geometry of lifter and mill speed should result in increased milling efficiency. In this work the influence of these operating parameters were investigated using a laboratory experimental mill. It is found that the power, are affected by number of lifters, lifter height, mill charge and mill speed. Overall the results showed that increasing the mill velocity, number of lifters, and height of lifter and significantly decreasing the mill charge filling results in a higher impact value and impact frequency that may also increase overall efficiency. A simple linear regression relationship has been demonstrated for mill power as a function of lifter spacing (S/H) and mill speed. These parameters give an indication of the possible optimum mill operating conditions in an idealised condition.     

Benefits of optimisation and model predictive control on a fully autogenous mill with variable speed

Autogenous (AG) milling is utilised around the world for particle size reduction. The system exhibits highly non-linear behaviour in addition to being subject to unmeasured variability associated with most ore bodies. Anglo American Platinum aimed at improving online optimisation of the circuit by implementing industrial model predictive control (MPC) to reduce system variability and continuously drive towards the optimal operating point within system constraints.The industrial dynamic matrix controller commissioned on the AG mill with a variable speed drive resulted in a 66% reduction in power and a 40% reduction in load standard deviation. These are the main controlled variables of the mill. The controller also improved the objective function, effective power utilisation, by 11%. This reduction in operated variable variability enabled a test campaign where the mill was controlled at various operating regions in order to establish the conditions conducive to the finest product size at a given mill feed rate.Moving the mill operating region from the benchmarked plant to the optimal grind environment and stabilising the mill at this point with the model predictive controller provided an estimated potential recovery increase of 0.32% (absolute) due to better liberation.     

Applying grindcurves to mill operation and optimisation

The operation of AG/SAG mills is sensitive to mill filling, therefore developing grindcurves to relate mill filling to performance indicators such as throughput, power draw, and product size can assist in achieving optimal mill operations. The throughput, power draw, and product size have been shown to peak at different mill filling levels. Establishing grindcurves can assist operators to decide on the best set point for operating their mill. Factors such as mill speed, mill inlet water, feed size distribution, and ore hardness all have an influence on the grindcurve, and form an integral part of the optimisation process.Test work has been conducted at a number of sites to develop grindcurves for different mills treating a range of ores. The results show great promise for use in optimising the operating set points for use in mill control. The methodology for developing grindcurves is described and the results from the case studies performed on fixed and variable speed mills are discussed.     

广义磨在火电行业的应用优势分析

随着我国国民经济的高速发展，对电力的需求日益增加，根据我国资源情况，目前火力发电仍占主导地位。在火电厂中，有三种主要物料需要粉磨：一是火电厂的主要燃料煤；二是脱硫用的石灰石；三是煤燃烧后的粉煤灰。下面对作为专利产品的广义磨系列设备粉磨上述三种物料的适应性进行分析。     

立磨机磨矿机理研究

本文分析了立磨机内磨矿介质的运动状态,分别讨论了磨矿介质在两个磨矿区域产生的不同磨剥作用,分析结果表明增大螺旋叶片直径和转速,减小螺旋升角有助于提高立磨机磨矿效率,但是为了能使立磨机磨矿效率最大化的同时降低磨矿能耗,必须综合考虑各种磨矿因素才能确定合理的结构参数和运行参数。     

Assessing the stirred mill design space

In the context of the mining industry, smaller grain size and other mineralogical characteristics have motivated the need to grind finer. In order to address this need, the interest in fine grinding technologies has grown over the last 20 years as is illustrated by a growing body of knowledge on stirred milling. Emphasis in recent years has been on the use of computationally intensive modeling and simulation methods such as the discrete element method (DEM) and computational fluid dynamics (CFDs). However, due to the computational requirements of these two methods, initiating a study that spans the stirred mill design space would take a lot of computational effort and time. Therefore the goal of this paper is to propose and apply a simplified stirred mill model that will then be used to assess configurations in the stirred mill design space.To this end, a stirred mill model was proposed based on the assumption that the main if not only mechanism of ore breakage is shear. As the basis of this model is the fluid mechanics definition of shear stress, the stirred mill power model became a function of viscosity, mill speed and a new parameter called shear volume. An initial validation using published data indicated the shear based power model correlated well with measured power.Establishing a morphological chart to delimit the stirred mill design space indicated that 24 design and operating conditions can be assess using the established shear volume measure. The results indicated for the mill configurations tested that a change in stirred mill liner design can potentially increase shear volume and power from 14% to 290% as compared to smooth chamber liners.     

基于ISAE的磨煤机故障预测与诊断方法研究

针对难以从火电厂实际运行数据中获得大量磨煤机故障数据,以及磨煤机精准数学模型难以求取,从而影响其故障诊断策略制定的问题,提出了一种基于简化机理模型的深度学习故障诊断算法,用于有效检测磨煤机的运行状态。基于磨煤机机理模型和状态空间预测控制器,构建了闭合控制系统,通过对不同故障类型的分析和模拟,在充分接近磨煤机的实际运行状态下,获得了大量的故障数据。并通过改进堆叠自动编码器(ISAE)将模拟的故障数据与深度学习算法相结合来建立深度学习故障诊断策略,ISAE以无监督的方式逐层提取故障数据的本质特征,具有很好的学习和识别故障特征的能力,同时通过将磨煤机系统变化快速且显著的变量作为ISAE输入变量,使ISAE兼具了故障诊断和预测的能力。仿真结果也表明,提出的ISAE能够很好地检测出磨煤机的故障,故障诊断准确率高达98.46%,并能提前发出预警。     

Power draw estimations in experimental tumbling mills using PEPT

Positron Emission Particle Tracking (PEPT) was employed to reconstruct the motion of mono-sized glass beads in an experimental tumbling mill run in batch mode. In each case, the derived trajectory field of a representative tracer particle was used to determine the charge power draw at steady state operation. Two approaches for calculating power draw were considered: the torque of the centre of mass about the mill centre, and the time averaged torque contribution per discrete grid cell summed over the volume of the mill. Results were compared across different operating conditions and particle sizes to measured power.