Effect of Rheology of Grinding Efficiency in the Laboratory Scale Continuous Classifying Mill

Abstract

Different ores containing soft minerals as the main components were ground in a continuously operating ball mill at laboratory scale. The effect of grinding conditions was studied by changing the solids feed rate, the feed slurry density, the weight of ball charge and the mill rotation speed. The optima of these variables in terms of energy consumption and production rate of fine fractions were determined individually for each tested ore. The grinding efficiency with this mill, equipped with a screen as a grate and a classifier at the discharge end, could be improved by lowering the slurry density to 25% solids by weight, which is significantly lower than traditionally used in laboratory tests or industrial practice.

The flow properties of the mineral slurries in question were studied as a function of percent solids for a better understanding of the phenomena observed in the grinding testwork. The viscosities of the mill discharge slurries were measured with different slurry densities. Tracer tests were conducted with different water/solids ratios in the mill feed for measuring the residence times of bulk solids, various size fractions and water, The maximum discharge rates of slurries from the mill were also measured with various slurry densities. The grinding results are discussed based on the conclusions drawn from these measurements.     

顽石作磨矿介质下含金铜硫矿的磨矿规律研究

以半自磨机排出的顽石作为磨矿介质,考察了顽石自磨磨损规律及其自磨产品粒度分布和顽石磨矿时顽石磨损规律及其磨矿产品粒度分布。结果表明：在不同的自磨磨矿时间、充填率和磨矿浓度下,顽石自磨损后产生的磨矿细度均在-0.125 mm以下;顽石作为磨矿介质时,在充填率为50%,浓度为60%,磨矿时间为19 min,入磨矿样为500 g的磨矿条件下,能获得-45 μm含量为60%的磨矿产品,其中新生-45 μm含量为18%左右;与钢球磨矿时矿物表面被大量的铁絮状物覆盖而遭到严重腐蚀相比,顽石磨矿时颗粒表面有少量絮状物,没有腐蚀带,矿物的轮廓平整、干净。顽石是一种细磨过程较为理想的磨矿介质。     

某高砷难溶金矿石浸出特性试验研究

采用超细磨、边磨边浸和强化碱浸等工艺方法考察了某高砷型难溶金矿石的浸出特性。其结果表明,超细磨、边磨边浸和强化碱浸工艺均能有效提高金的浸出率。矿样超细磨至-37μm占99.7%时,金的氰化浸出率从23.7%提高到73.6%,金的非氰化浸出率从18.5%提高到66.9%;在同样磨矿细度条件下进行边磨边浸,而后再继续浸出,金的氰化浸出率进一步提高到82.4%,金的非氰化浸出率提高到72.9%;在同样磨矿细度条件下进行碱浸预处理,碱浸6~9 h金的氰化浸出率为88.3%~87.5%,碱浸9~12 h金的非氰化浸出率为89.7%~90.2%。     

钨矿石磨矿动力学研究

建立和预测磨矿过程的产品粒度分布数学模型有助于指导选矿厂磨矿实践.文中在实验室条件下对柿竹园钨矿石进行不同磨矿时间的分批磨矿试验.结果表明,矿粒在0.1 mm及其以下粒级符合一阶磨矿动力学,在0.1 mm以上粒级符合n阶磨矿动力学.一阶磨矿动力学参数k与粒径d呈幂函数关系,其动力学方程为R=R₀exp[-（0.014 42+9.538 65d1.761 28）t];n阶磨矿动力学参数中,k与粒径d呈幂函数关系,n与粒径d呈对数函数关系,其动力学方程为R=R₀exp[-（-0.134 1+1.151 42d0.681 69）· t0.718 18-0.386 56lnd].利用建立的磨矿动力学方程计算出的理论值与磨矿实际结果进行比较,其吻合程度较高,为选矿厂通过调节磨机给矿量和分级机返砂量来控制磨矿产品粒度奠定理论基础.      

昆钢大红山提高8.53×4.27m半自磨机处理量实践

通过对半自磨机给料粒度合理搭配;调整半自磨机钢球尺寸;调整半自磨钢球补加量来控制磨机合适的充填率;格子衬板改造;排矿直线筛筛孔改造;半自磨机给矿自动化控制等改变了半自磨工艺,提高了处理量并降低了半自磨机的钢耗和电耗,达到了很好的效果。     

半自磨机排矿速度及粒度优化研究

半自磨机磨矿介质由钢球和矿石自身组成,随着矿石硬度及块度的增加,造成半自磨机排矿速度偏慢及排矿粒度组成不合理,影响系统台效及电力、钢球等消耗。半自磨机为强制排矿碎磨设备,可通过改变排料端设计,将直形排料端改为弧形结构,优化半自磨机的排矿速度及粒度组成,达到提高半自磨系统磨矿效率的目的。     

湿式磨矿机橡胶衬板的研究

橡胶衬板不受腐蚀,但受到浓酸的损害。今天,不同的磨矿场所,采用不同质量的橡胶,获得最好的经济效果。
橡胶衬板不能仿照船舵型或波形锰钢衬板的形状。找出正确的压条衬板（提升棒）的间距和高度的比率是很重要的。
就磨损观点来看,橡胶衬板最重要的磨损因素是给矿粒度,磨矿介质尺寸,磨机转速和简体直径。当从钢衬板改为橡胶衬板时,人们通常不愿意改变这些因素。
一般认为,采用的钢球尺寸越小,磨矿效率越好。二段磨矿机应用橡胶衬板总比钢衬板得到更好的经济效果。棒磨机用橡胶衬板获得良好的经济效果。     

城门山铜矿磨矿基础自动化完善

磨矿流程是选矿生产中一道重要生产工序，其受来料矿石性质、磨机衬板损耗、钢球与给水大小等多种因素共同影响，难以建立精确的数学模型。同时磨矿产品粒度、浓度对后续浮选流程具有重大影响。城门山铜矿磨矿流程历经多次技术升级改造，已具备了较高的自动化水平，实现了给矿、给水等稳定控制。随着技术的进步，近年来陆续进行多项技术改造，采用变频技术控制磨机，安装新型仪表等多项工作，进一步提升了磨矿流程的控制水平。     

城门山铜矿磨矿基础自动化完善

磨矿流程是选矿生产中一道重要生产工序,其受来料矿石性质、磨机衬板损耗、钢球与给水大小等多种因素共同影响,难以建立精确的数学模型。同时磨矿产品粒度、浓度对后续浮选流程具有重大影响。城门山铜矿磨矿流程历经多次技术升级改造,已具备了较高的自动化水平,实现了给矿、给水等稳定控制。随着技术的进步,近年来陆续进行多项技术改造,采用变频技术控制磨机,安装新型仪表等多项工作,进一步提升了磨矿流程的控制水平。     

提高选矿厂磨矿系统效能的技术改造及应用研究

选矿厂磨机运行的优劣程度对于整个选矿厂生产经营工作的重要性不言而喻,因此,如何采用简便、高效且实际可操作的方法来提高磨矿效能一直是广大选矿工作者研究的重点。目前,选矿厂衡量磨矿效能的参数主要有磨机利用系数、单位磨矿能耗和磨矿成本等。某选厂对球磨机运行状态进行了大量的检测及研究,通过优化磨机内部结构、调整内部钢球级配来适应磨矿负荷的变化,确保达到球磨机内部参数的最优状态,从而实现以较少的投入提高磨矿效能的目标。     

JM2200BF型立磨机在德兴铜矿尾矿回收厂的应用

因给料粒级宽泛,含铜矿物嵌布粒度细的特性,传统球磨机难以达到细磨的要求,德兴铜矿尾矿回收厂采用JM2200BF型立磨机取代球磨机,并对立磨机介质充填率、搅拌转速、磨矿浓度等相关运行参数进行了工业调试及优化。与球磨机相比,立磨机的使用使现场磨矿效果得到了极大的改善,并可获得较好的经济效益。     

Grinding gray cast iron chip

Studies have been made on the grinding conditions for SCh21-40 gray cast iron chip of sizes from 10 × 2 × 0.2 to 20 × 5 × 0.5 mm in vibrating mills containing various media. During dry grinding, the mean particle size falls for 6 h, but after 7 h there is agglomeration. Grinding in the presence of distilled water is most effective when the mill body cooling system is switched off. The grinding in that case is accelerated by a factor of 1.5–2.Deceased.Translated from Poroshkovaya Metallurgiya, No. 11 (359), pp. 7–11, November, 1992.     

提高选矿二系列磨矿细度的工艺改进

磨矿细度是指磨矿产品的粗细程度,入选颗粒的大小直接影响浮选指标的高低。通过对直线振动筛筛网的筛孔尺寸、球磨机补加钢球直径大小、球磨机钢球补加制度、旋流器给矿压力的大小这些影响磨矿细度的相关工艺进行改进,提高了选矿二系列的磨矿细度,为降低尾矿含铜提供合适的入选原矿。实践证明这些改进措施确实可行。     

提高选矿二系列磨矿细度的工艺改进

磨矿细度是指磨矿产品的粗细程度,入选颗粒的大小直接影响浮选指标的高低。通过对直线振动筛筛网的筛孔尺寸、球磨机补加钢球直径大小、球磨机钢球补加制度、旋流器给矿压力的大小这些影响磨矿细度的相关工艺进行改进,提高了选矿二系列的磨矿细度,为降低尾矿含铜提供合适的入选原矿。实践证明这些改进措施确实可行。     

高能球磨制备Zr-V纳米粉末

将初始Zr粉和V粉按一定比例混合 ,用高能球磨设备制备Zr V纳米粉末 ,利用XRD和SEM及TEM研究研磨过程中粉末的物相及粒度变化。结果表明 ,粉末的晶粒尺寸随研磨时间的增加而减少 ,适当增加转速 ,可以缩短晶粒细化时间 ;通过高能球磨可以制备出粉末晶粒尺寸在 10nm左右 ,粉末颗粒尺寸在 6nm左右的Zr V混合粉末     

特大型磨机在乌山铜钼矿的应用

乌山铜钼矿是国内最早应用国内自主研发的特大型半自磨机、球磨机的矿山企业之一。经过多年的生产实践,持续对磨矿工艺流程和设备进行优化改进:将SABC碎磨工艺流程改为SAB磨矿工艺流程,增大了处理矿量,解决了磨矿系统给矿及磨矿粒级分布等工艺指标不稳定的问题;提高磨机钢球充填率,缩减半自磨机格子板的顽石窗,采用区间优化加球法添加钢球,采用自动化控制方式。生产实践表明:近3年来设备运行平稳,设备运转率始终保持在92%以上。磨矿处理量已超过设计产能的15%,取得了巨大的经济效益。     

Ball-Mill Grinding Kinetics of Cement Clinker Comminuted in the High-Pressure Roll Mill

The use of high-pressure grinding rolls (HPGR) prior to ball mills has become a common practice in cement clinker grinding due to significant energy savings in comparison to ball milling alone. The energy savings has been attributed to higher energy efficiency of HPGR at low reduction ratios, smaller particle top sizes in the ball mill feed, and the weakening of particles resulting from compression of particle bed by HPGR. This study attempts to show how the weakening effect changes the kinetic breakage parameters of the HPGR-treated clinker. For this purpose, batch ball mill experiments were conducted with three narrow-size fractions (?3.35 + 2.36, ?1.70 + 1.18, and ?0.85 + 0.60 mm) of the feed and product samples of an industrial HPGR, and the breakage rate and breakage distribution parameters of the samples were compared. The results show that the weakening effect leads to nonlinear breakage rates for all sizes, coupled with abnormal breakage at the two coarsest sizes. The weakening effect leads to increased breakage rates of the HPGR product relative to particles of the HPGR feed. The increased breakage rates are accompanied by coarser progeny distributions for the two coarsest size ranges relative to that of the HPGR feed. The progeny distribution of the finest size of the HPGR product, however, is finer than that of the HPGR feed. Ball milling of size-distributed feeds prepared from the HPGR product and feed samples for the same grinding time produces self-similar size distributions when the size is normalized with respect to the median size.     

半自磨机顽石作为实验室立磨机介质的磨损与磨矿研究

随着半自磨流程在国内大型矿山的日益普及, 对如何处理半自磨机磨矿过程中产生的顽石, 各选厂采用的方式不尽相同.利用半自磨机顽石充当立磨机磨矿介质处理这类顽石并对此开展顽石的磨矿条件试验研究, 包括:磨矿时间、充填率、磨矿浓度和磨矿处理量等条件试验, 以及顽石、钢球磨矿介质对比试验.试验结果表明:半自磨机顽石可以作为磨矿介质在立磨机内使用, 其损耗量相比较于传统钢球的损耗量 (大约0.05 %) 是较大的, 一般在1 %~2 %之间.在磨矿时间3 min、填充率60 %、磨矿浓度65 %、磨矿量5 kg时可获得满足浮选要求的磨矿产品.在磨矿时间3 min、立磨机转速210 r/min、磨矿浓度65 %、磨矿量5 kg、磨矿介质直径10~20 mm、充填率60 %的条件下进行顽石和钢球磨矿介质的磨矿对比试验, 结果表明, 钢球磨矿产品的细度比顽石磨矿高16.72 %, 过粉碎粒级产率高2.35 %, 钢球的磨矿效率大于顽石, 但顽石磨矿产品中0.045~0.038 mm的产率高于钢球磨矿, 说明顽石充当磨矿介质时易使被磨矿物磨细到嵌布粒度的大小, 会使产品粒度分布更合理.      

Acceleration of mechanical size reduction of chromium carbide powders and mixtures based on chromium carbide

We have investigated how mechanical activation by rolling on smooth rollers affects the dispersion kinetics of chromium carbide powders and mixtures of chromium carbide powder with nickel in a ball mill. We have shown that preliminary double rolling of chromium carbide powder on a rolling mill accelerates particle size reduction in the ball mill down to a size of 1.4–1.5 μm by a factor of 4.6 compared with unrolled powder. In this case, the size reduction increases from 36 to 91 in relative units. The mean particle diameter for the powders and mixtures decreases exponentially as the grinding time increases from 12 h to 84 h. Translated from Poroshkovaya Metallurgiya, Nos. 1–2(411), pp. 1–8, January–February, 2000.