矿浆浓度及粒度组成对某锌浸出渣分离粒度及磨矿参数的影响

某锌精矿冶炼厂拟采用闭路磨矿方案来改善砂磨机对一段浸出渣的磨矿效果。针对冶炼厂工艺要求尽量少补加水的实际,本文对采用闭路磨矿后矿浆浓度、粒度组成对分级机效果的影响及磨机参数的调整方案进行了探索研究。黏度测量结果表明,矿浆黏度随矿浆浓度的增加呈指数式增大,随-40μm粒级含量的增加而增大;分离粒度的计算结果表明,旋流器分离粒度受给矿浓度的影响更显著,分级浓度应控制在55%以内;通过模拟磨机给矿进行了磨矿参数的优化试验,结果表明,选择5 mm刚玉球作为磨矿介质,搅拌器线速度4.43 m/s可以取得较好的磨矿效果。     

矿浆浓度及粒度组成对某锌浸出渣分离粒度及磨矿影响

某锌精矿冶炼厂拟采用闭路磨矿方案来改善砂磨机对一段浸出渣的磨矿效果。针对冶炼厂工艺要求尽量少补加水的实际,本文对采用闭路磨矿后矿浆浓度、粒度组成对分级机效果的影响及磨机参数的调整方案进行了探索研究。黏度测量结果表明,矿浆黏度随矿浆浓度的增加呈指数式增大,随-40μm粒级含量的增加而增大;分离粒度的计算结果表明,旋流器分离粒度受给矿浓度的影响更显著,分级浓度应控制在55%以内;通过模拟磨机给矿进行了磨矿参数的优化试验,结果表明,选择5 mm刚玉球作为磨矿介质,搅拌器线速度4.43 m/s可以取得较好的磨矿效果。     

某选厂磨矿分级工艺改造与自动化控制系统研究

某铁选厂原采用螺旋分级与磨矿构成闭路,存在着分级返砂量不稳定、不连续且分级能力较差的问题,影响磨矿效果。同时为实现磨矿分级作业流程中磨机给矿量、充填率、磨矿与分级浓度等技术指标的自动化控制,建立了磨矿分级自动化控制系统。通过采用旋流器代替原螺旋分级机对磨矿产品进行分级,采用PID控制器控制磨机给矿、旋流器泵池液位与分级压力,通过水量的控制进行磨矿与分级浓度的调节,使用自动加球机控制磨机充填率,设计了控制系统硬件,确定了控制流程,最终实现了磨矿分级作业流程的自动化控制。其中磨矿控制的关键点是保证球磨机的充填率和磨矿浓度,分级过程控制的关键点是旋流器的压力与分级浓度。实践结果表明,采用旋流器分级并建立磨矿分级自动化控制系统,可根据矿石性质的不同自动调整给矿量,降低了返砂比,提高了磨矿效率和分级效率,实现了钢球自动添加,有效降低了钢耗。该选厂磨矿分级工艺的改造与自动化控制系统建立的实践结果,有利于提高选厂自动化生产的整体水平。     

进料水力旋流器性能试验研究

文中对轴向进料水力旋流器和普通切向进料水力旋流器的性能进行了对比试验，分析结果表明：轴向进料旋流器处理量较切向进料旋流器增大20％左右，底流浓度、底流产率、分级效率较切向进料水力旋流器有所降低。但底流粒度较粗，粒度组成均匀。因此轴向进料旋流器可用于进料浓度较低时粒度较粗颗粒的分级作业。     

青海某金矿选厂一段分级作业改造实践

青海某金矿选矿厂原一段磨矿—分级作业使用螺旋分级机进行分级,分级效率仅34.84%,底流-0.074 mm含量高达16.31%,大量已单体解离的有用矿物返回磨机再磨,矿浆泥化严重,影响浮选指标,且螺旋分级机故障率高,不利于生产成本的降低,需进行技术改造。固定水力旋流器给矿浓度55.00%、给矿压力0.06 MPa,将原螺旋分级机替换为FX500-4旋流器组,并通过工业试验优化沉砂嘴直径。改造后,一段分级效率提高到46.39%,底流-0.074 mm含量由16.31%降低到10.80%,矿浆泥化现象得到明显改善,节约了浮选药剂成本,金回收率由76.08%提高到78.82%,一段分级设备运转率提高到92%,综合效益显著。     

渐扩进料体旋流器分级性能试验研究

针对水力旋流器处理细粒级颗粒分级时易出现溢流跑粗的问题,设计出一种渐扩式进料体旋流器,并通过粉煤灰的分级试验,研究底流口直径、压力、给料浓度对其分离性能的影响。研究表明,随着底流口直径增大,底流浓度减小、底流产率升高、分级粒度变细,分级效率明显增大;随着压力增大,溢流浓度减小,底流浓度明显升高,分级效率升高;随着给料浓度增大,溢流和底流浓度都升高,底流产率减小,分级效率降低。当底流口直径为Φ18mm、压力为0.06MPa、浓度为16%时,旋流器分离粒度d50为54μm,且-54μm分级质效率为49.50%,量效率为88.66%;此时,溢流-45μm含量达到88%以上,符合一级灰标准。     

水力旋流器用于一段闭路磨矿工艺

在金属矿山行业中，选矿厂采用水力旋流器替代笨重而又占地面积大的螺旋分级机用于一段闭路磨矿分级工艺，实践证明溢流细度、分级效率、循环负荷、磨矿效率等均有显著提高，处理能力弹性大，磨机功耗下降，粒度组成和浓度对下游工序更为有利，是更加有效的闭路磨矿分级手段。     

舞阳铁矿磨矿系统自动控制的应用

针对舞阳铁矿选矿磨机系统的现状，通过变频调速技术和可编程序控制器PLC的应用，对给矿量、磨矿浓度、分级溢流浓度、水力旋流器的给矿压力、浓度等进行自动控制改造，提高和稳定磨矿能力，减少停机时间，保证粒度、品位合格率，降低了球耗、电耗及衬板消耗，减轻了劳动强度。     

磨矿回路中两次分级新工艺—提高分级效率的有效途径(摘要)

目前国内外选矿厂多数采用磨矿机-螺旋分级机或磨矿机-水力旋流器的磨矿回路,少数选矿厂采用磨矿机-水力旋流器-细筛回路。水力旋流器已成为重要的分级设备。然而,当前所用的分级设备,均存在分级效率低的问题。水力旋流器常有溢流跑粗、底流夹细,分级效率在27～60%左右,即约有40～60%合格的矿粒返回磨机,螺旋分级也约有60%的合格矿粒被返回磨机。如克里沃洛采选公司第三段磨矿回路,水力旋流器沉砂中含72～80%合格的粒级产品,分     

旋流器底流口直径及入料性质对固体颗粒运动的影响研究

结合水力旋流器分级原理,利用计算流体力学的原理和方法,在底流口直径和入料性质参数多个水平下,对旋流器内部流场进行了数值模拟,揭示了两因素对旋流器分级的影响。结果表明:增大底流口直径,流场内流速降低,零速包络面向内向上收缩,分级粒度变小;增大入料固体颗粒密度、粒度或者质量浓度,固体颗粒指向中心的径向速度减小,底流产率增加,细颗粒含量增加。根据选煤厂的实际生产工况,合理设计旋流器的结构参数,对控制分离粒度、提高分级效率尤为重要。     

Grinding capacity enhancement by solid concentration control of hydrocyclone underflow

A control strategy to increase the mineral feed tonnage in grinding operations was developed and evaluated in an industrial mill. The control strategy maximizes the solid concentration at the hydrocyclone underflow discharge while keeping the particle size constant. The manipulated variables are the set-points of the fresh solids rate controller and the sump water flowrate controller. The system was tested in two grinding circuits at El Teniente Division, Codelco-Chile. Results showed a 5–12.5% increase in treatment capacity while the product size at the hydrocyclone overflow was kept under control (25%+150 μm). Alternatively, the extra capacity generated by the optimizing control strategy can be used to shutdown some of the grinding circuits without losing the actual plant capacity. Also, the dynamic response of the grinding circuit was characterized for open loop step changes in fresh mineral rate and sump water flowrate.     

给矿粒度分布对半自磨-球磨回路磨机选型的影响研究

采用在JKSim Met软件平台上的流程模拟方法研究给矿粒度分布对年处理550万t某铁矿矿石的半自磨—球磨回路磨机选型的影响。研究结果表明,减小给矿粒度可显著降低所需半自磨机和球磨机的尺寸及驱动功率,从而降低磨矿回路的投资和运行成本。     

基于PLC和WinCC的磨机给矿量模糊控制系统

针对某选矿厂一段磨矿回路,设计了一种基于S7-300 PLC和WinCC的磨机给矿量模糊控制系统。该系统采用设定值模糊控制算法和模糊PID控制算法设定磨机给矿量和实时整定K_P,T_I,T_D参数,很好地实现了某选矿厂一段磨机给矿量的稳定控制。     

Analysis of specific discharge rate functions in industrial scale cement grinding multi-compartment ball mills to assist ball mill modeling

Specific discharge rates in industrial scale multi-compartment cement grinding ball mills were determined using industrial scale data to assist modeling of multi-compartment ball mills. Multi-compartment ball mill model structures were proposed to estimate normalized specific discharge rate functions. Multi-compartment mills were divided into perfectly mixed mill segments to describe material transport mechanism in the mill. Specific discharge rate functions were determined by using the estimated mill hold-up for perfectly mixed mill segments at the steady state condition of the cement grinding circuits. Estimated normalized discharge rate functions were found to be different than the basic pattern observed in semi-autogenous mills due to the differences in design and operational conditions of the mills. Coarse particle accumulation was found to have a significant effect on discharge rate function pattern. Estimated normalized discharge rate functions could be used in modeling of multi-compartment ball mills.     

The effect of the design of a secondary grinding circuit on platinum flotation from a UG-2 ore

Platinum concentrator plants experience significant losses in their overall Platinum Group Elements (PGE) recoveries due to the inefficiencies of their secondary grinding circuits. This study involves an investigation of selective grinding of the platinum-bearing silicate particles present in UG-2 platinum ores found in the Bushveld Igneous Complex (BIC).Batch-scale laboratory test work was done to investigate the effect of a secondary milling circuit configuration, using a hydrocyclone underflow sample from a UG-2 concentrator plant as feed material. The envisaged secondary milling circuit consists of a conventional hydrocyclone to de-slime the feed followed by density separation with a spiral concentrator to separate the ore into lights (silicates-rich) and heavies (chromite-rich) fractions, followed by separate milling of the two fractions in parallel ball mills, and combined rougher flotation. A full-scale spiral was run in batch mode, followed by separate milling of samples in a 200 mm diameter mill and combined flotation in a 4.2 l cell. The milling energy inputs were re-distributed between the lights and heavies mills to determine the effect on the platinum mineral rougher flotation recovery and the Cr entrainment.The most promising results were found with 88% of the energy input to the lights mill and 12% to the heavies mill. The results indicated that under batch conditions, the secondary rougher flotation recovery (69% 4E) was similar to the conventional mill-float circuit (70%) however the Cr entrainment was significantly reduced by approximately 40% (2.3–1.4% Cr).This test work has confirmed the benefit of separate milling in the secondary milling circuit for a UG-2 ore. Spiral concentrators have shown potential as an effective density separating device to produce a silicate-rich and chromite-rich fraction for milling; further test work will be conducted to confirm its viability on an industrial scale.     

Vertical Agitated Media Mill scale-up and simulation

Vertical Agitated Media Mill modeling has become subject of a research project due to its potential application as a secondary grinding mill as well as regrind and pellet feed preparation projects. A test campaign with a pilot scale vertical mill was carried out with five different ore samples to elaborate a simple and robust methodology to scale-up vertical mills and perform simulations. The methodology proposed considers breakage parameters determined from tests in a conventional batch ball mill and population balance model for simulations. The tests can be performed very quickly in any process laboratory with a small quantity of sample. Two different models can be used for scale-up purposes: the first is based on the specific grinding energy and the corresponding tests were carried out on samples with natural size distribution. The second is based on particle residence time distribution and the tests carried out with narrow sized particles. Breakage and selection function parameters were estimated from each test procedure. The results indicate that it is possible to perform vertical mill scale-up and simulations with acceptable accuracy using the results from laboratory ball mill tests. The data analysis showed that the ratio of grinding net powers between ball and vertical mills is approximately 1.35 for all samples tested.     

Is media shape important for grinding performance in stirred mills?

Models for understanding the basic concepts of fine grinding and how they apply to the design of stirred media mills have not yet matured. While spherical media in tower mills has previously been studied, real grinding media shape in stirred mills can range from spherical (steel/ceramic balls) to highly non-spherical (sand or slag) resulting in very different media and grinding dynamics. Handling the contact mechanics of non-spherical particles is a challenge for numerical models, and very few studies dealing with non-spherical particle shape exist in the literature. Discrete Element Method (DEM) simulations of dry media flow in a pilot-scale tower mill are performed for four cases with different shaped grinding media, in order to understand how flow and energy utilisation within a stirred mill depend on media shape. Differences in media transport, stress distribution, energy dissipation, and liner wear were observed in the tower mill for the spherical and non-spherical cases. A significant departure from sphericity of the media leads to strong dilation of the bed, reduced bulk density, and a reduction in active volume and collisional power levels leading to a reduction in power draw for the mill. In addition, highly non-spherical media tend to pack tightly near the mill walls forming a near solid layer around the inside of the mill shell which results in poorer transport and mixing, as well as increased wear rates on the screw impeller. Grinding performance in stirred mills appears to deteriorate strongly when using highly non-spherical media.     

Comparison of energy efficiency between ball mills and stirred mills in coarse grinding

Stirred mills are primarily used for fine and ultra-fine grinding. They dominate these grinding applications because greater stress intensity can be delivered in stirred mills and they can achieve better energy efficiency than ball mills in fine and ultra-fine grinding. Investigations were conducted on whether the greater performance of stirred mills over ball mills in fine grinding can be extended to coarse grinding applications. Four different laboratory ball mills and stirred mills have been tested to grind seven ore samples with feed sizes ranging from 3.35 mm to 150 μm. A case study on full scale operations of a 2.6 MW IsaMill replacing the existing 4 MW regrind ball mill at Kumtor Gold Mine in Kyrgyzstan is also included. This paper summarizes the major findings from these investigations.     

齐大山铁矿选矿分厂二次分级旋流器参数优化研究

鞍钢集团矿业公司齐大山铁矿选矿分厂采用溢流型球磨机与水力旋流器组合,用于一段、二段闭路磨矿分级工艺。自投产以来,二段磨矿分级效率低,一直制约着后继工艺的选别作业。通过采用国产FX660-GX水力旋流器与进口Krebs水力旋流器的对比和水力旋流器参数优化,结果表明,采用180 mm的溢流管、135 mm的沉砂口配置的水力旋流器,可以满足现场工艺的要求。     

JS-872型磨矿过程控制系统研究

本文分析了球磨机一螺旋分级机闭路磨矿过程的控制对象特性,提出自动校正设定值的给矿量定值控制和分级机溢流浓度及其流量的控制策略,吸取了常用的控制方式,研制成JS-872型控制系统,经过五年多的工业运行,取得了良好的技术经济效果。