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万能材料试验机设计【5张CAD图纸和说明书】

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关键词：: 万能材料试验实验设计 cad 图纸以及说明书仿单

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第1章概述 1

1.1课题的提出 1

1.1.1课题产生的背景 1

1.1.2 课题的意义 1

1.2国内外实验机研究的回顾、现状及发展趋势 2

1.2.1国内外试验机发展及其趋势 2

1.2.1国内外各种实验机的介绍 5

1.3课题的内容： 7

第2章万能材料试验机总体设计 9

2.1加载方式 9

2.2 试验机式样的选择 9

2.3传动方式的对比与选择 9

第3章运动动力设计与验算 14

3.1滚珠丝杠副的运动动力设计计算 14

3.1.1静载荷条件 14

3.1.2丝杠寿命计算 15

3.1.3丝杠强度计算 15

3.1.4丝杠的稳定性 16

3.1.5丝杠的刚度 17

3.1.6丝杠的传动效率功率 19

3.1.7滚珠丝杠几何参数 19

3.2电机的选择 20

3.3各轴功率，转速，转矩的计算 21

3.4各级传动的设计计算 21

3.4.1带传动设计计算（同步） 21

3.4.2蜗轮蜗杆减速器的计算 22

3.5支撑滚珠丝杠的轴承的选择及验算 26

3.6动静横梁变形的验算 28

3.6.1动横梁变形的验算 28

3.6.2静横梁变形的验算 29

第4章总结 31

参考文献： 32

摘要

试验机是在各种条件、环境下测定金属材料、非金属材料、机械零件、工程结构等的机械性能、工艺性能、内部缺陷和校验旋转零部件动态不平衡量的精密测试仪器，可以对材料进行拉伸、压缩、弯曲、剪切、扭转、冲击、疲劳、蠕变、持久、松弛、磨损、硬度等试验。近年来，试验机行业技术突飞猛进。试验机向着两个方向即超微外力检测与超大外力检测发展。高检测精度、高灵敏度、运动平稳、易于操纵是目前试验机的主要发展方向。

本文首先概述了试验机的基本定义、分类与国内外一些重要生产商的成果。第二部分论述了所想到的四种方案并对这些方案优缺点作了分析和对比。在彼此比较后决定选第一种方案。第三部分则是说明了试验机的主要机械传动部分的设计以及对它们的校核过程。试验机的传动部分主要由蜗轮蜗杆、皮带、滚珠丝杠三部分组成。经过校核后所有设计均符合要求。在文章的最后简明的介绍了做本次毕业设计的一些心得体会。

关键词试验机；蜗轮蜗杆；齿形带；滚珠丝杆；

ABSTRACT

Test machine in various conditions and environment in metal materials, non-metallic materials, machinery accessory, engineering structures such as mechanical properties, technics performance, Internal defects and checking dynamic imbalance rotating parts of sophisticated testing equipment, such as materials tension, compression, bending, shear, reversing, impact, fatigue, creep, lasting and relaxation, wear, hardness tests. In recent years,the technic of the test machine industry advances rapidly. Test machine is the direction toward the development of the super-tiny force detection and the development of super-large external force testing. Detection of high-precision, high sensitivity, smooth motion, easily operated test machine is the main development direction presently.

This paper first summarizes the test machine's basic definition, classification, and some important domestic and foreign manufacturers results. The second part, discussing about the experiences of the four projects as well as advantages and disadvantages of these projects are analyzed and compared . In comparison with each other decide the first option. The third part is the experiment, the major part of the mechanical drive design and the process of checking them. The main drive system of the test machine includes the worm, toothed belts, ball screw three components. After checking all the design had complied with the request. In the end concisely introduce the meeting and what had learned in the graduate design experiences.

Keywords: Test Machine, Worm Gear & Worm，Toothed Belts，Ball Screws，

第1章概述

1.1课题的提出

1.1.1课题产生的背景

作为专业本科毕业生，为了能在走上工作岗位之后更快地进入职业角色、我们需要在通过毕业设计这一环节初步地将自己在大学四年中所学习到的知识应用到实践中去。所以在指导老师的引导之下，我选择了万能材料试验机设计这个题目。

1.1.2 课题的意义

通常,把测定材料机械性能的仪器和设备称为材料试验机。但是，有些国家有时把测定材料物理性能（甚至化学性能）的仪器和设备也称为材料试验机。

国外，在工业比较发达的国家中，对于试验机的研制和生产，都是比较重视的。这是因为，材料试验机作为一个基础工业部门，对于工业生产和科研工作有直接的不容忽视的影响。

实际上，对于工业生产和各种工程设计来说，材料试验机是确保各种机器，车辆，船舶和结构物的合理设计与安全运行的重要测试设备。因为，为了既经济又安全可靠地从事各种工程设计，必须根据材料的机械性能选取合适的材料。否则，可能造成浪费，或者导致发生严重的事故。而要获得准确的材料机械性能数据，只有使用材料试验机。

在工业生产特别是军事工业生产中，为了保证产品质量，常常需要对各种材料和零部件或整机进行检定和测试。许多重要性的热处理零部件，如轧钢机的钢辊，机器的主轴和汽车的连杆等，都要百分之百的进行硬度检定。

在冶金工业生产中，随着科学技术的飞速发展，也提出了许多新问题。例如现代技术的发展，需要一些具有特殊性能的，能在高温，低温，高压，高速以及各种复杂条件下工作的材料，因此必须研制新型材料与合金。钢铁厂生的钢材，也需要随时检验。显而易见，所有这些研究和检验工作，离开材料试验机是无法进行的。

上述几点，已足以说明材料试验机的发展对航空，冶金，机械，建筑和造船等工业部门，在合理设计工程结构，节约材料，提高产品质量，改进工艺和降低成本方面具有重要的意义。

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内容简介：: 1Batu Hijau七年的运行与持续发展Batu Hijau 从 1999 年开始投产运营，从 2001 年开始不断致力于改进系统的形式,以使其品牌生产能力每天超过 12 万吨。通过由矿山选矿厂，使厂矿集中，并在矿石处理中不断改善突破生产瓶颈。本文所要讨论的改进措施主要包括以下几个方面：扩建了磨凹陷破碎卵石、混合电路增强燃爆和混合程度碾磨有效性凹陷磨衬板、壁炉、除浆升降机的优化磨机钢球大小和负载气旋和气旋水泵改良升级升级过程控制成本控制措施绪论Batu Hijau1999 年 9 月委托制作的品牌容量每日 120 吨碾磨机其可靠性达到 92。家的粉碎巡回是由最初的回旋决定的，直径 36 尺寸的 SABC 凹陷碾磨机由陆上运输和贮存到供给两条平行的磨合线构成，直径 20 英寸的小钢球和1000 个小圆石排进行撞击。McClaren et. al.描述设计时说到，建筑和第一个两年运作重在大的细节, 不会再修改实施文件，除非为今后断续改善提供相关资料。第一年运作由于被很多设备的可靠性，实用性困扰，其生产能力相对于品牌产品低了一些。在 2001 年间通过改进操作和保养程序以及许多小型设备的改进使设备的可靠性和碾磨生产能力得到提高。在这段时间里由于铜和黄金价格降低对 Batu Hijau 生产率和营业成本的提高产生重大压力。通过 2001 年战略经营的回顾得出，通过消除薄弱生产加工环节达到了提高生产率的目的。从总体上增加单位技术含量并降低相对成本支出，抓住这个时机将会在未来几年内获得更多利润。这些论述在文件里有详细描述。生产历史由于操作程序改进和矿石坚硬程度具有易变性，Batu Hijau处理生产率也是在改变的。不过技术改进对矿石坚硬增量的弥补超过了过去几年，允许操作持续超出的设计容量(参见图1)。2图 1: 20002006 生产率和混合物铜和金生产率如下图 2 所示，并且随季节变化逐步采用介入开采的采矿计划，旱季期间从坑的底部，雨季开始再从坑底部回到上边。磨料成分中铜可能从干季的少于 0.5到湿季的超过 0.9。这些季节性波动使清洁器浮选精矿和浮选精矿处理操作时在高干旱季节里存在很大难度。图 2: 铜等级的季节性变动漂流碾磨小卵石的扩展击碎流程小卵石击碎电路最初被安装在 Batu Hijau (下页, 图 3) 被许多操作程序干扰, 其维护困难和容量问题如 McClaren (2001)所描述。一个重大操作问题是有限的超负荷能力导致流入混合的频繁溢出，要求直接装货人员亲自清洁。在 2000 年末对溢出滑道进行了修改，传动机被安装在回归容器溢出处，直接传送混合物到下陷磨房，消除了对装货人员自行清洁的要求。小圆石传送路线包括垂直传送的铲斗，将岩石投入设备过程中对其造成频繁损伤，并且铲斗产生频繁颤动，从而引起整体安全，维护和清洁问题。2000年和 2001 年打击衬垫过早破坏主要归因于这些桶传送机和钢珠残缺不全，这些缺陷不能解决之前，小卵石击碎过程有效性有待提高。2001 年正式批准推翻原方案，全部按传统传送小圆石装置重新完成传送装置设计和压碎器设施设计。传送机图 3: 原始的 Batu Hijau 粉碎流程图系统包括四块大的 Eriez 传送带磁体，其中两块在交叉带子处，另两块被安装在传动机调动点以改进钢珠移除方式。该设施已经完成并且现有的两台小卵石压碎器开 2002 年 2 月被调迁到现场固定安装。该设施改善了小卵石线路的实用性以及名义上的碾碎率，其效率更高超过每天 5000 吨。然而钢球从压碎器移除时由于数量很多，碾碎筒筛相对磨房料库过大而有反回的可能，所以这仍然是3一个有待解决的问题。典型大小 2030mm 的多边形废弃物球很快通过漂流到达下陷碾磨机矿石筛产生巨大的爆炸声。如果这些小钢珠被理没在传动机上，那么他们将不能被有效地吸附在磁铁上。磁铁运转更远处并且在附近存在磁铁矿，那么磁铁的磁性就将会被削弱了。金属探测器作为压碎机进料器的最后防线能够有效的使钢珠保留在压碎器处面。设备运行中要求操作人员能够对压碎器的金属探测器可能出现的差错作出反应，并在小卵石中找出被埋没的钢珠。延长初级压碎器的维护周期和适当的休眠对于贮存并迅速进入球磨房进料器很有必要。每隔几分钟金属探测器运行到压碎机进料器时小卵石巡回导致小卵石压碎器变得不能动作直到主压碎器在联机控制下使探测器返回。2003 年期间对球磨机作了更改使矿石筛和废弃物隔离，将废弃物带到垃圾填埋场，并使喷涂剂用量减少，这样消除了由于小卵石撞击引起的损伤。粉碎回路的容量传统上受到磨碎机或小卵石的限制。回顾 2002 年消除薄弱环节的方案，使其吞吐容量增加到 10000 吨，10mm 以下的小卵石直接进入磨碎机，10mm 以上的小卵石再次被送回进行磨碎，这样磨碎机基本上处于开放的状态。工厂条件下试用结果证明产品改进将使小卵石不再循环时磨碎机效率提高，对于新进原料每一吨被击碎的小卵石中有 0.5 到 0.6 吨没被回收到自动磨碎机进料器中。改进后的流程图如图 4（下页），需要增加第四台 MP1000 压碎器（在2003 年 3 月完成），并且在 7.3m 振动筛基础上制成 3.6mm 振动筛（2003 年 7 月完成）。由于消除了从磨碎机回收击碎的小卵石，使初始小卵石的生产率下降了 20%。把磨碎机开口从 60mm 增大到 80mm 以提高小卵石的生产率使其达到先前水平。由于矿石筛自重问题，小卵石在机械和操作上遇到了一些困难。矿石筛机械件的高度磨损，要求另处的预防性维护，其筛选强度降低，矿石筛筛选效率同时降低。由于使小卵石进入气旋产生强烈挤压，旋风进给泵和水力旋流器衬垫磨损率大幅上升。小卵石压碎器的运行改进使有效性从少于 60%到超过 80%，安装的马达由于更加均匀的进料和矿石筛重新布置最大负荷提高其平均压碎器牵引力从原来的60%提高到 80%，在磨碎机矿石筛卸料斜槽安置静态的筛子以从压碎器进料中除去钢珠，改善从磨碎机小卵石脱水情况。另外由于早期钢珠的损伤使压碎器衬垫疲劳直至破裂。图 4：提高开矿爆破和混合力度磨碎机进料大小对生产率产生很大影响，2006 年较有影响的论述是被(RQD)收录的一篇论述，其磨碎机进料大小和磨碎机生产率关系如图 5（下页）。2002 年分裂照相机设施被安置在磨碎机传送器上，允许发展改进的矿石特性描述手段，4针对岩石类型设计爆破方案，从而减少了流入磨碎机进料器石块大小的可变性。在 2004 年改进过的标准爆破方案进入实践操作阶段，在坚硬的岩石中使用高浓度火药粉，在软的断裂的岩石中用低浓度火药粉。在最坚硬的矿石方面生产量提高 1015%的预期计划 2004 年实践操作证实了该数据。由于矿石混合注入进料器，新爆破技术的应用，生产率相比年计划提高了 27%。矿石类型特性描述技术的改进使磨碎机矿石生产能够预期交付，其混合优化也使磨碎机的生产量和金属生产率得到最大程度的提高。图5：RQD Effect on SAG feed size and SAG Throughput, afterBurger et al (2006)磨碎机在有效性方面改进之后，其寿命可靠性由设计的 92%提高到 94-95%超过以往的几年。这些进步是改善维护计划施行维护计划，改进碾碎组分，辅助设备设计及某一设备升级的结果。主要改善是 2004年磨碎机重新布置同时在巡回路线上提供更加频繁的维护机会，使整个线路更加整洁。每年跟踪管道停机48小时维护一条磨碎生产线，另一条线也同时停机维护。将气旋进给泵从 GIW24/22 升级到 Krebs28/26，同时在 2004 年对暖泵进行例行维护的时间由原来的五个星期延长到十二个到十三个星期。 Batu Hijau 在每个球磨机只安置一台气旋进给泵，减轻本身重量，减轻振动引起的破坏，停工维护以级磨碎机的不断改进提高了工作有效性超过0.5%。从 2001 年开始橡胶式矿石筛被安装在磨碎机和球磨机面板上，面板设计中扩大了磨损范围，使最大磨损区的使用寿命从原来的 2-3 个星期延长到 12个星期。其中聚氨酯面板的磨损贡献数几乎是 1%不计算在内。 2001 年停工检修期间发现大型卵石和碾磨球进入旋风进给泵和气旋，因此适当的预防性维护成功的避免的重大事故的发生。 2002 年改进小卵石巡回路，从小卵石回路中除去了垂直的桶传送机，提高小卵石可用性到 90% 。在磨碎机上安装了 100mm 厚的橡胶衬里块和陶瓷砖，放电洗涤槽和废水坑，减少了修理这些设备的停工频率，同时也减少了排除泄漏的无计划停工维护时间。5图6：Annual Total Mill Availability磨碎机衬垫，壁炉和浆液举升机的设计优化磨碎机衬垫设计试验和检验原始的磨碎机衬垫的设计在 Batu Hijau 上是 72 行顶部呈帽子形式的小凸起，并与齿面角成 12 度。选择衬垫和举升机的最优组合并在磨碎机上进行测试，最大限度的提高磨碎机生产率延长衬垫使用寿命。对两台磨碎机送入同样物料，保证在一定时间内同样条件下接收到相同进料，性能对比表明，并不受贮存分离程度的影响。McClaren et. al. (2001)所记述的 48 行的帽形衬垫设计与 72行的衬垫相比其生产率和磨损率相去甚远。与 MEI 制造厂商合作设计出 36 行的举升机和衬垫并于 2001 年投入使用，使磨碎机在其生命周期内的生产率提高了23%。一些根据技术细则手册设计的 36 条垫板的并发的产生,在生产率上没有和第一个测验中所显示的那样表现出同样的进步.磨机的性能和 72 条机构一样。36 条设计继续遭受垫板的过早破损,导致了在垫板寿命的最后一到两个月里未意料到的停工期。磨机垫板设计的 DEM 模型说明代 25 度齿面角提升机构的 36 条提升机构和盘状垫板能提高生产率.在 2002 年 12 月这套垫板的安装没有显示出明显生产率的提升。这套垫板过早破损而迫使在使用了仅仅三个月之后就要去除这些垫板。36 条垫板在运行中引起了一些问题.在使用一样的卸料筛,装球量和充料速度下与 72 条垫板设计相比 36 条垫板平均形成了多出 50%的卵石.由于卵石的增加卵石非常脏,恶化了卵石循环输送和低下的卵石碰撞性能所带来的问题.在精细的矿石填充的情况下 36 条设计磨机不能有效的提升,因为比 72 条设计磨机更低的生产率.而在粗糙矿石填充的情况下,36 条设计比 72 条垫板设计更胜一筹。36 条垫板设计中的垫板盘的过早破损和涉及到在生产率没有任何改善下卵石循环性能的运行问题的结合,导致了 2005 年两种磨机 72 条设计被重新使用的决定。72 条有 15 度的提升机构齿面角,并且别加强来增加垫板总磨损寿命。将来对于垫板设计的修正把目标定在在不影响生产率的情况下增加磨损寿命。SAG 磨机筛和矿浆提升机构SAG 磨机筛和矿浆提升机构以及卸料机构一直在经历着为提高可维护性,卵石制造率和磨机卸料率方面的改进。筛孔从一开始就在稳定的增加。在 2000 年一个 25 毫米和 60 毫米结合筛发展到 2001 年 40 毫米和 60 毫米结合筛.到 2002年所有 60 毫米筛的使用为维持卵石制造和磨机生产率成为了必要。卵石碰撞筛的安装之后 90 毫米筛试验不久便开始。当前筛结构使用的是比 80 毫米筛更均衡的 80 毫米和 60 毫米的结合筛.三分之一筛的替换维持了新和部分旧筛的混合和贯穿筛总寿命的平均筛孔和开口区域。以前所有筛的替换由于更低的开口区域和筛孔尺寸最初减少了磨机生产率。6筛孔尺寸的每个改动符合压低卵石生成量的粗糙充料量和矿石硬度的的增加。随着粗糙充料量降低更少卵石率,卵石生成率已经典型的达到了 15-22%。随着 2002 年磨机生长率的提高, 因为磨机突然停止时观测到的矿浆池的存在,SAG 磨机卸料能力在非常高的生产率下变成了一个阻碍。研磨最后的完全卸料由 Metso 赞助进行重新设计使筛与磨机前部分离,这样是为了在靠近磨机出料口制造一个更深的矿浆提升机构髓室和增加矿浆排出能力。筛磨损的观测说明部分内筛很少在磨机上的矿石内部充料机构里所以对去除磨机内矿浆或者卵石没什么作用。然而从筛背面的磨损可以看出它带来了矿浆明显回流到滚筒的现象。外筛被延伸内筛的剩下部分被封锁。这种改变减少了在重新换板停工期间需要替换的量,通过减少回流到研磨室的量提高了矿浆排出量。研磨钢球尺寸和填充Batu Hijau 半自动磨机被设计来使用伴随着 12-14%125 毫米钢球的使用率的改变。2002 年装球量逐渐增长到 18%并且产生了研磨生产量上的明显提高.2003 年的一项试验中减少磨机中钢球填充量到 14%,证实了生产量 5-10%的降低.钢球填充量现在维持在 16-18%。133 和 140 毫米大钢球的试用最初旨在增加磨机产量但是可预测的影响没被重视.但是随钢球尺寸的增加总钢球消耗量减少了,随着 80 毫米筛孔的采用这变得更加重要.现在的磨机普遍采用 133 毫米钢球,钢球消费率为 0.4kg/t。主动控制成本Batu Hijau 管理者从车间工厂实际出发，不断促进文化进步并寻找公司新的理念。这些想法也许对于普通雇员实施起来很快很容易，但在管理者那里具体操作过程中就是要节省维修及其它费用。实行对多种操作能力的员工的小褒奖制度，引入持续竞争的思想。另外一些更加鲜明的主动节省成本的描述包含在下面这个报告中：从磨碎机碾磨房废弃物中回收钢珠加入球磨房在运转过程中下部机构支撑区域保持动力供给选择更加有效的试剂作反应物地方与全球供应商同步预购结论Batu Hijau 磨碎机的连续改进表明未来将设计生产量比过去几年更加优越的磨碎机。经过对正常的商业案例的瓶颈和发展的系统鉴定，证明获取重要过程收益的关键在于降低基础设施成本。这些工程已经改变了规格不等的设计和材料设备供应商,为流程变革投入重要的工程和资本开支。参考书目B. Burger, K. McCaffery, I. McGaffin, A. Jankovic, W.Valery, D. La Rosa,2006, “Batu Hijau Model for Throughput Forecast, Mining and MillingOptimisation and Expansion Studies”, pp.461-479, Advances inComminution, Edited by Komar S. Kawatra, SME, 2006.McClaren, D., Mitchell, J., Seidel, J., Lansdown, G., 2001, “The DesignStart-up and Operation of the Batu Hijau Concentrator”, International7Autogenous and Semautogenous Grinding Technology 2001, Volume IVof IV, pp, IV-316-335, Edited by Derek J. Barratt, Michael J. Allan,Andrew L. Mular, Pacific Advertising Printing & Graphics, Delta, BC,Canada, 2001BATU HIJAU SEVEN YEARS OF OPERATION AND CONTINUOUSIMPROVEMENTABSTRACTSince the 1999 commissioning of the Batu Hijau concentrator, a systematic approach of continuous improvement has allowed the concentrator to exceed its name plate production capacity of 120,000 tonnes per day since 2001. Production improvements were achieved by de-bottlenecking the ore treatment process from the mine through the concentrator.This paper will discuss improvements in the following areas: Expansions of the SAG Mill pebble crushing circuit Enhanced mine blasting and blending efforts Mill availability SAG mill liner, grate and pulp lifter optimisation Mill ball size and load Cyclone feed pump and cyclone upgrades Process control upgrades Cost control initiativesINTRODUCTIONThe Batu Hijau Concentrator was commissioned in September 1999 with a nameplate capacity of 120,000 tonnes per day at 92% mill availability.The comminution circuit comprised primary gyratory crushing, overland conveying and stockpiling to feed two parallel grinding lines in SABC configuration with one 36 foot diameter SAG mill, two 20 foot diameter ball mills and one MP1000 pebble crusher per line. McClaren et. al.(2001) described the design, construction and first two years of operation in significant detail and will not be revisited in this paper except to provide context for subsequent improvements. The first year of operation was plagued with numerous equipment availability issues and less than name plate throughput rates. By mid 2001 equipment availability and mill throughput rates had improved to design levels through improved operating and maintenance practices and numerousminor equipment modifications.Around this time copper and gold prices were depressed which added significant pressure to production rates and operating costs at Batu Hijau. A strategic operating review was conducted in 2001 to identify de-bottlenecking opportunities from the mine through the process plant with the aim of increasing production rates. The study concluded that opportunity existed for significant throughput increases from a range 8of incremental unit improvements at relatively low capital expenditure.These opportunities were captured on a master list and tackled in turn over subsequent years. The major initiatives are described in the body of this paper.PRODUCTION HISTORYProcess production rates have been variable over the life of Batu Hijau due to process improvements and variable ore hardness. Progressive increases in ore hardness have offset throughput gains over the past several years but have allowed the operation to continue to exceed design capacity (see Figure 1).Copper and gold production rates, as shown in Figure 2, have also varied due to seasonal phasing of mining plans which involve mining as much high grade from the bottom of the pit during the dry season but then pulling out of the pit bottom at the start of the wet season. Mill feed grades can vary from less than 0.5% Cu to more than 0.9% Cu between wet and dry seasons. These seasonal fluctuations have placed pressure on cleaner flotation and concentrate handling capacity during the high grade dry season periods.EXPANSIONS OF THE SAG MILL PEBBLE CRUSHING CIRCUITThe pebble crushing circuit originally installed at Batu Hijau (next page,Figure 3) was plagued by a number of operating, maintenance and capacity issues as described by McClaren (2001). A significant operational problem related to limited surge capacity in the crusher feed bin producing frequent overflows of the surge bin, requiring immediate loader cleanup. In late 2000 the overflow chute was modified and conveyors installed to return bin overflow directly to the SAG mill feed belts to eliminate the loader rehandle requirement.The pebble conveying circuit included vertical bucket conveyors which generated a range of safety, maintenance and cleanup problems from the bucket conveyors 9flinging rocks into the plant and frequent damage to the bucker conveyor belts. Poor pebble crushing circuit availability in 2000 and 2001 can be largely attributed to these bucket conveyors and incomplete removal of steel balls from the pebble crusher feed resulting in premature failure of crusher liners. In 2001 approval was given for addition of one crusher and complete redesign and installation of conventional conveyors to transport pebbles.to and from the new crusher installation. The conveyor system included four large Eriez belt magnets two in cross belt and two installed on conveyor transfer points to improve steel ball removal. The installation was completed and the existing two pebble crushers relocated to the new crusher building in February 2002. This installation improved pebble circuit availability significantly and increased nominal milling rates by more than 5,000 tonnes per day.Removal of steel from crusher feed was still a problem with the new circuit however, due to the practice of returning large quantities of ball mill trommel oversize to the SAG mill feed stockpile. Reject balls from the ball mill are typically 20-30mm polygonal steel shapes which pass directly through the SAG mill and report to the SAG mill trammel oversize. If these small steel balls are buried on the conveyor they can not be effectively recovered by the magnets.Magnet operation was further complicated by the presence of some magnetite in the ore so that magnet sensitivity was reduced. Metal detectors on crusher feeders have been effective as the last line of defence to keep steel balls out of the crushers. Operating practices require operators to respond to a metal detector trip of the crusher feeder and locate the steel ball buried in the pebbles. Periods of extended primary crusher maintenance have necessitated dozing of stockpiled ball mill scats into the mill feeders. The resulting flood of ball chips into the pebble circuit resulted in the pebble crushers becoming.inoperable until the primary crusher came back online as metal detectors were tripping crusher feeders every few minutes. By mid 2003 modifications to both SAG and ball mill trommels screens and sprays reduced the volume of ball mill scats so they could be effectively segregated and taken to a landfill site, this has eliminated steel ball chips from pebble crusher feed.10Capacity of the comminution circuit had been traditionally SAG mill or pebble crusher limited. A review of de-bottlenecking options in 2002identified a change to the pebble crushing circuit would produce a nominal 10,000 tpd increase in total circuit throughput by directing the minus 10mm portion of pebble crusher product directly to the ball mills and the plus 10mm portion returned to the pebble crushers, essentially open circuiting the SAG mills. The production improvement was justified on plant trials demonstrating increased SAG mill feed rates when pebbles were not recycled, with increases of 0.5-0.6 tonnes of fresh feed for every 1 tonne of crushed pebbles not recycled to the SAG mill feed. The modified flowsheet shown in Figure 4 (next page), required the addition of a fourth MP1000 crusher (completed in March 2003) and two 3.6m by 7.3m single deck Schenck vibrating screens (July 2003).On start up of the pebble screens a 20% drop in pebble production rate from the SAG mill was noted due to the removal of recycled crushed pebbles from the mill feed. This decrease allowed the mill discharge grate apertures to be opened from 60mm to 80mm to increase pebble production rates to previous levels.The pebble screens have suffered from mechanical and operating problems due to a combination of light weight screen design, high wear on screen structural members requiring additional preventative maintenance and poor screening efficiency due to thick operating bed depths. Wear rates of cyclone feed pumps and hydrocyclone liners also increased due to the introduction of sharp crushed pebbles into the cyclone feed.Pebble crusher operation improved from less than 60% effectiveutilisation to over 80% and average crusher power draw increased from 60% to 80% of installed motor power as a result of more consistent feed rates due to the recirculating load of screen oversize, improved dewatering of SAG mill pebbles through installation of static grizzly screens in SAG trommel discharge chutes and elimination of steel balls from crusher feed. Crusher liners are now worn out rather than cracking early due to ball damage.ENHANCED MINE BLASTING AND BLENDING EFFORTSThe effect of SAG mill feed size on throughput rates is significant and is discussed by Burger et al (2006) who illustrated the influence of in-situ fracture spacing in the rock as measured by Rock Quality Index (RQD)on SAG mill feed size and mill throughput 11rate is shown previously in Figure 5 (next page). Installation of Split cameras on SAG mill feed conveyors in 2002 allowed development of improved ore characterisation and tailoring blast designs to rock types to reduce SAG mill feed size variability. Modified blast designs were standardised into a drill and blast cookbook in 2004 which use high powder factors in competent ores and conserve powder in softer/fractured ores.Throughput improvements of up to 10-15% on the hardest ore types were modelled and subsequently verified with operating data in 2004.Due to the mix of ore types in mill feed the application of the cookbookblast designs have improved throughput rates by 2-7% on an annual basis.Improved characterisation of ore types has improved mill throughput predictions and optimisation of mine ore delivery blends to maximize mill throughput and metal production rates.MILL AVAILABILITYMill availability and utilisation (Figure 6, next page) has improved over the life of the project from less than design of 92% to 94-95% over the past few years. These improvements have been the result of improved maintenance planning, execution of maintenance plans, modifications to mill component and ancillary equipment designs and complete upgrades of certain equipment. Major improvements have been. Simultaneous SAG mill relines commenced in 2004 to provide more frequent maintenance opportunities on the tailings pipeline and cleaner flotation circuit. Annual tailings pipeline maintenance with only one SAG mill line being worked on resulted in 48 hours of lost availability on the other grinding line. Upgrade of cyclone feed pumps from GIW 24/22 to Krebs 28/26 and Warman Ash 650 pumps in 2004 extending time between maintenance shutdowns from 5 weeks to 12-13 weeks. As Batu Hijau only has one cyclone feed pump installed per ball mill reducing frequency and duration of pump driven downtime improved mill availability by 0.5%. Installation of rubber trommel panels in SAG and ball mills from 2001 and improved panel designs extended wear life from 2-3 weeks to 12 weeks in the highest wear zones. Failure of polyurethane panels contributed to almost 1% 12unplanned downtime in 2001 and allowed large pebbles and grinding balls into the cyclone feed pumps and cyclones. These types of failures are successfully avoided with proper preventative maintenance. Pebble circuit upgrade in 2002 removed the vertical bucket conveyors from the pebble circuit, increasing pebble circuit availability to 90%. Installation of 100mm thick rubber liner blocks and ceramic tiles in mill discharge launders and sumps has reduced thefrequency of downtime required for this repair work and unplanned downtime to repair leaks.SAG MILL LINER, GRATE AND PULP LIFTER OPTIMISATIONSAG Mill Liner Design Trials and TribulationsThe original SAG mill liner design at Batu Hijau was a 72 row H

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