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国内外煤用破碎设备分类与代表机型摘要：本文简述了当前我国国内以及国际上主流的煤用破碎设备及其分类，以及其所代表的机型，并且对它们进行了一些概述。本文还介绍了现如今的不同破碎设备的工作原理和它们的优缺点。关键字：破碎机、分类、代表机型Classifications of coal crushing equipments and their representative types at home and abroad He Ning(School of Chemical Engineering and Technology，China University of Mining and Technology，Xuzhou 221008，China)Abstract: This article sketchs current popular coal equipments at home and abroad and their classifications and their representive types.These types are also summatized.It introducts working principles and relative merits of different crushing equipments.Keywords: Crusher; classifications; representive types引言：破碎设备对煤炭的作用其实就是使得煤炭磨碎之后能够让煤块的粒度去达到能入选的粒度要求，或者能够使得选煤厂选好的煤炭去达到客户对产品的粒度的需求，又或是为了对原煤的后续加工而提前做好了准备。其实破碎的方法可以有很多很多种，有挤压破碎的方法、劈裂破碎的方法、折断破碎的方法、冲击破碎的方法和研磨破碎的方法。正是因为有这么多的破碎方法，所以才会有那么多不同的破碎机械。而按照工作的原理的不同和结构特征的不同等原因可以把破碎设备划分为：颚式破碎机、圆锥破碎机、辊式破碎机、冲击式破碎机和磨碎机。随着科技的不断发展和时代的不断进步，破碎设备也是会随着选煤工艺和技术的不断发展而不断进步的。不管是中国，还是外国，在选煤的设备上，都做了不少的创新和突破，希望能使破碎设备能用最低的投入来产生最大的效率。本文就是阐述了近几年国内外破碎设备的发展和新机型。1、辊式破碎机1.1、破碎设备辊式破碎机是相对较老的一种粉碎、破碎机械，这种机械并不适宜去用作破碎比较坚硬的物料，常常用于中等硬度或者松软物料的破碎。其主要的优点是：结构较为简单，他的机体紧凑便捷，工作比较可靠，价格相对来说比较低廉，调整辊式破碎机的破碎比比较方便，破碎时比较少的出现过粉碎的现象。1工作原理及代表机型2：辊式破碎机工作运行的主要部件是由两个齿辊构成，这两个齿辊是平行安装的，每一个齿辊都沿着它们的轴向安装了许多的破碎齿。需要进行破碎的物料在进入辊式破碎机后，物料受到了重力和辊面的摩擦力的作用，然后被带入了双辊之间，在受到了辊子上破碎齿的碾压剪切后，然后物料破碎。代表的机型有：PLPG-320x250A型盘辊式破碎机、轮齿式双齿辊破碎机、2PGL双齿辊破碎机、2PGC820型破碎机、860型破碎机和700型破碎机等3-5。1.2、分级设备最近30年内，世界的范围内才出现了分级破碎机，它是一种较为新型的破碎技术。分级破碎机使用的是较低齿辊转速度、较高扭矩以及特定的辊齿的形状，从而对进入的物料进行粒度上的控制和进行分级破碎的任务。机器内的两个齿辊是分级破碎机工作运行的主要的部件，这两个齿辊是平行安装的，而且每一个齿辊都有沿着它的辊轴的方向布置了一定量的破坏齿环。当要破碎的物料进入到分级破碎机后，就会被双齿辊上的鹰嘴型破坏齿紧紧地咬合住，这样就使得物料会慢慢地受到了齿辊的剪力和拉力，最终在这两个力的作用下而破碎。分级破碎机的破碎齿辊的旋转方向有两个，可以分为内旋和外旋这两种方式。当分级破碎机采用的是内旋破碎的方式时，那么这样的分级破碎机就是以对物料的破碎为主了；然而当该分级破碎机采用的外旋破碎方式时，那么该分级破碎机就不是对物料进行破碎为主了，而是以分级为主了。1.2.1、分级破碎机的特点6分级破碎机具有以下几行列出的具有显著的技术特点：1） 产品的粒度有保障。分级破碎机采取固定中心距的方法，通过这种方法来达到对给入物料的强行破碎。要依据给入物料的粒度要求对齿和齿辊的结构尺寸进行了设计。因此，分级破碎机严格地控制了最终产品通过的尺寸，从而满足了对粒度的要求。2） 同时具有破碎和筛分的双重功效。分级破碎机同时具有破碎的功能和分级的功能。这样的机器就可以有效地削减掉进行单独筛分的那一部分。从而减少了对筛分设备的需求，这样就可以节省不少的经费。3） 物料分配均衡。电子计算机对破碎的齿辊进行了仿真的设计，使得它不仅仅实现了对给入物料的均衡分配，而且又能保证在破碎过程中的连续性。4） 产品粒度可调。破碎后产品的粒度能够调节，那么就可以根据用户的不同需求而进行调节，从而满足客户。5）整机高度低、无振动。由于分级破碎机的整体的高度相对较低，因此分级破碎机对厂房楼层的高度要求并不是不高。6）破碎机产生的粉尘量比较少、破碎机的处理能力较大、生产所需的能耗低。1.2.2、国内外代表的分级破碎机在最近的几年，海内外在分级破碎机的技术制造水平上有了许多突飞猛进的发展。比如SSC超大处理能力分级破碎机、DSSC新型四齿辊分级破碎机、轮齿式分级破碎机、2PLF系列新齿型分级破碎机、UFP分级破碎机、2PLFX和SSCX系列细碎型分级破碎机、强力分级破碎机和刮板分级破碎机等，这些都是现如今在世界范围内得到广泛使用的设备6。2、颚式破碎机该破碎机中的两块颚板其实就是颚式破碎机工作运行的主要部分了。两块颚板其中的一个是固定颚板也就是我们常说的定颚，固定颚板以垂直的方式或者是使它的上端略微的外倾的方式把颚板固定在破碎机机体的前壁上，而另外一个就是活动颚板也就是常说的动颚，动颚的位置相较起来更倾斜，动颚和定颚形成了一个上面大、下面小类似倒三角的破碎腔室。在破碎腔内中，活动颚板相对于固定颚板进行具有周期性的往复运动。有时它们俩远离，有时它们俩又接近，当这两块颚板分开时，破碎的物料就进入了破碎腔，而那些已经完成了破碎的物料则从下部排卸而出；当这两块颚板相互靠近时，在此之前进入到这两块颚板之间的物料就会受到两块颚板的挤压，在弯折以及劈裂的作用下破碎，则完成了破碎的工作。正是因为颚式破碎机它的整体结构较为简单，制造起来还比较容易，破碎机工作时也相对可靠，而且在使用和维修等等的方面上都有比较方便等优点，所以使得颚式破碎机在许多地方有着比较广泛的使用。2.1、分类颚式破碎机可以按照活动颚板也就是动颚，它的摆动方式的不同，能把颚式破碎机大致的可以分为简单摆动式颚式破碎机即我们简称的简摆颚式破碎机，复杂摆动式颚式破碎机即所称的复摆颚式破碎机，最后还有的综合摆动式颚式破碎机这三种。2.2、国内外具有代表性的颚式破碎机为了去改善颚式破碎机工作的性能，以及为了提高颚式破碎机的工作效率，国内外的研究人员都相继的研发出了公众的颚式破碎机。主要有：简摆双腔颚式破碎机，这种破碎机的主要特点是有着比较大的破碎比，出来的产品细度比较低，而且这种破碎机让间歇性的运动转变成连续性的运动；双动颚颚式破碎机，这种破碎机其实就是在两个活动颚板破碎机的基础上进行改造，也就是去把这两个破碎机的前墙全部拆掉，然后就使得两个活动颚板破碎机对置而变成的一个单一大破碎机，这种破碎机具有能强制卸料、生产的能力较高、使用的寿命长等等的特点；外动颚匀摆颚式破碎机，这种破碎机的特点就是产品处理能力强、机体的外型相对较低、给料口的高度和机体的重心也比较低、产品破碎比大等特点。83、圆锥破碎机圆锥破碎机可以用来破碎细碎的物料和中碎的物料以及不同硬度的物料，该破碎机是一种可以进行连续的作业，工作效率也比较高的破碎设备。圆锥破碎机由于处在矿石的破碎生产线的最后的阶段，因此它有着比较重要的地位，同时也是选矿厂的关键。圆锥破碎机它的主要结构有偏心套、水平轴、控制系统、液压系统机架、上破碎壁(固定锥)、液力偶合器、下破碎壁(动锥)、动锥体、液力偶合器、平衡轮、润滑系统等好几部分组成。当圆锥破碎机开始工作时，电动机就通过带动圆锥破碎机里面的传动装置，从而带动偏心套的旋转，然后里面的动锥在偏心轴套的被迫运动下做旋转的摆动，动锥在靠近静锥的那个区段就成为了破碎腔。给入的物料在受到了动锥和静锥两者多次的挤压作用和撞击作用后，然后被这两种力所破碎。当动锥离开了这个区段的时候，则此处物料就已经破碎到了要求的粒度，这时物料在受到自身重力的作用下下落，从而最终从锥底排出。3.1、圆锥破碎机的特点1）、更高的产能，更高的质量要求2）、具有保险的装置，该装置可以保证大大地减少停机的时间3）、破碎机的机体是由铸钢构成的，将加强筋安在重载的部位4）、具有调节器，能够快速的调节破碎颗粒的粒度5）、提供弹簧式保护装置7）、封闭性好8）、使用寿命长6）、具有润滑系统3.2、国内外圆锥破碎机的代表机型国内外的圆锥破碎机都有着非常多的类型，各类型的破碎机都不一样，即便是同一种类型的破碎机，也会因为是由不同厂家生产而使得这种破碎机和其他同一型号的破碎机之间存在着些许的差距。其中主流的的圆锥破碎机有：单缸液压圆锥破碎机、多缸液压圆锥破碎机以及惯性圆锥破碎机等。4、冲击式破碎机我们把冲击式破碎机进行简单的划分，可以把它分为锤式破碎机以及反击式破碎机。锤式破碎机可以利用它在破碎腔里面高速旋转的锤头，锤头产生的冲击力将其进入到破碎腔内的物料撞击到腔内的衬板上而破碎掉，破碎后的物料在腔内达到了规定的粒度要求后，就会通过腔内下部的筛条从而排出。而那些落在了衬板上，却还未达粒度要求的物料也就会受到了锤头的研磨作用，物料慢慢地被研磨最终降低了粒度。直到所有的物料都通过了筛条。锤式破碎机它可以适用于中细碎物料等中等硬度即脆性的物料，它具有生产效率比较高、破碎比大、尺寸相对的凑紧、运行功耗较少、维护和使用简单等特点。反击式破碎机工作原理与锤式破碎机的相类似。它是通过破碎机内部的转子高速的旋转，当物料进入到了该破碎机的破碎腔后，就会与高速旋转的转子上的板锤发生撞击从而破碎。由于具有动能，被撞击后的物料又继续运动，然后打击到腔内的反击板上而再次产生撞击而破碎。同时在破碎腔内的随机四处运动的物料之间也会产生相互的碰撞而破碎。反击式破碎机它具备着破碎的效率比较高、破碎后的出料粒度小并而比较均匀、容易受损的零件也少、维护起来比较的方便、运行的功耗较低等特点。84.1、国内外代表冲击式破碎机国内外具有代表性的冲击式破碎机有环锤破碎机、单转子锤石破碎机、单转子反击式破碎机和可逆反击锤式破碎机等等。5、旋回式破碎机最近才出现的旋回式破碎机，这种机器是圆锥破碎机的一种。旋回式破碎机广泛地用于对大型矿山和其他工业各种硬度的矿石进行粗碎。与颚式破碎机相比较来说，旋回式破碎机的主要优点就是它的破碎过程是沿着圆环形的破碎腔连续进行的，而圆锥破碎机并不是连续进行的，而且旋回式破碎机的生产能力较大而且破碎粒度比较均匀。旋回式破碎机由上机架而构成了定椎体，主轴上安装着动锥，衬板都安装在了动锥和定锥上，于是它们就构成了破碎腔。通过电动机的传动装置从而带动动锥运动，从而达到了对物料的破碎，完成破碎后的产品通过它的自重排出。85.1、国内外代表的旋回式破碎机国内的PXF型旋回破碎机、国外的SUPERIOR MK-II型旋回破碎机6、结语随着我们国家的发展、我国对于煤炭需求的增加和对产业的节能以及技术性能的重视，选煤厂工艺的不断更新是大势所趋，因此往后的选煤厂里面的设备肯定就会要求使用最小的能耗从而来达到最高的产能。随着现在国外破碎机的研究技术的不断进步和不断发展，我们国家的破碎机技术从此不能再停留在一味对国外的设备进行模仿，和国内的厂商间互相模仿的那一步，这样就会使得我们陷入闭门造车的地步。因此，国内的研究者和厂商需要不懈地努力，这样才能使得我国破碎机的发展取得傲人的成绩，让现在的破碎设备得到不断的完善，使我们自己掌握这自己的新技术而不再需要依靠国外的。参考文献：1陈建中、沈丽娟、赵跃民.选矿机械2陈磊、张会霞、贾鲁帅. 辊式破碎机在煤矿主煤流运输中醮推广与应用J.科技创新论坛，2013：227-2283李大磊，陈松涛，马胜钢，吴宛生.新型盘辊式破碎机的研发J4张见宝，苏凯，王磊，潘贵阳，马明. 轮齿式双齿辊破碎机破碎齿冠受力计算及有限元分析J. 矿山机械，2013（006）5邓德玉. 2PGL双齿辊破碎机在杏花洗煤厂的应用J. 煤炭技术,2011（003）6王全强.分级破碎机研究及应用现状J.煤，2013（163）:22-247安福顺，张丽颖.几种大型煤用中细齿辊破碎机的比较J.矿山机械，2011（007）:164-1658高强，张建华.破碎理论及破碎机的研究现状与展望J.机械设计，2009（10）：72-74任务书院（系） 专业年级 学生姓名 任务下达日期： 20xx年 3月 5日设计（论文）日期：20xx年 3 月5日至 20xx年 6月 15日设计（论文）题目：宁安公司新汶矿业1.80Mt/a矿区型炼焦煤选煤厂方案优化与工艺布置设计（论文）专题题目：国内外煤用破碎设备分类与代表机型设计（论文）主要内容和要求：主要内容：1 完成一座1.80Mt/a矿区型炼焦煤选煤厂方案优化与工艺布置； 2 撰写一篇专题论文； 3 专题论文翻译。要 求：1 设计内容技术要求入洗原煤为所在矿区一矿和二矿生产的两种毛煤，入洗比例为：一矿：二矿=56：44；至少有一个精煤产品满足下列要求：灰分Ad=(8.519.00)%；水分Mt12.00%；设计内容包括：资料分析与计算、方案论证、流程计算、设备选型及主厂房工艺布置；工程概算；在进行选煤厂总体布局时应适当考虑选煤厂的办公和生活服务设施； 车间布置图不少于4张，设备流程图、数质量流程图和工业广场总平面布置图各1张；均采用计算机绘制。 2 专题论文要求 论文内容必须与设计内容有关； 论文字数在30005000之间； 论文格式满足一般科技文献出版要求。 3 资料翻译完成不少于3000字的规定英文资料翻译；译文要求能够表达原意，语句通顺，文笔流畅。 4 所有资料提供电子文档一份。 5 提交设计说明书、概算书、专题论文及专英翻译合订本一册。院长（系主任）签字： 指导教师签字：1 英文翻译原文The behaviour of mineral matter in ne coal otation using saline waterSchool of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, QLD 4072, AustraliaAbstract：In this study the behaviour of mineral matter in the otation of a ne coal sample using saline water was investigated. For a comparison, de-ionised water was tested in parallel. It was found that saline water increased the recovery of mineral matter while increasing the combustible recovery. By calculating the degree of entrainment in the otation of the coal sample and also the ash after combustion, coupled with the froth image analysis and rheology measurements of froth and pulp suspensions, the entrainment and entrapment of mineral matter in coal otation were examined. Compared to de-ionised water, saline water increased the entrainment across the size range and the increase in entrainment was more pronounced for particles smaller than 38 lm.However, entrapment played a more important role in recovering mineral matter smaller than 38 lm in coal otation using both de-ionised and saline water. Saline water signicantly increased the entrapment through enhancing the aggregation of coal particles.1. IntroductionCoal mining is an important business in Australia supplying coal to produce 85% Australias electricity. 54% of the coal mined in Australia is also exported, mostly to Eastern Asia. In the last few years there has been a distinct change in the water quality used in coal preparation plants within Australia due to stringent policy on the amount of saline water which a mine can discharge into the local river system. As a result, most coal mines have introduced water re-use as a conventional practice. One of the consequences of increased water re-use is a concomitant increase in the salinity of water on the sites and subsequently in otation. A number of studies have been conducted to investigate coal otation using saline water. In general, saline water increases combustible recovery compared to fresh water 15. However, these studies have not taken into account the behaviour of mineral matter in saline water.With the depletion of coal resources, more and more low-grade and difcult coal deposits are being processed and the role of saline water in recovering mineral matter in coal otation becomes important.It is known that the recovery of particles by otation is a function of true otation and mechanical entrainment. In mineral otation the pulp of solid particles in water is conditioned with collectors (a type of surfactants) to render value minerals hydrophobic, while gangue minerals remain hydrophilic. Air is then injected into the pulp to form bubbles that collide with particles.Hydrophobic particles tend to attach to the bubbles and the bubbleparticle aggregates are then transported to the pulp/froth interface at the top of the pulp and eventually enter the froth launder as the concentrate. This process is called true otation. However, mechanical entrainment of particles taking place when particles are dragged by the interstitial liquid lms between air bubbles always occurs in parallel with true otation and is the primary recovery mechanism for gangue, especially nes 6. Due to its unselective nature and the fact that gangue minerals are generally abundant in the ore, the recovery by entrainment may have a signicant detrimental effect on the concentrate grade.Entrainment in otation can be considered as a two-step process, including the transfer of the suspended solids in the top of the pulp region just below the pulpfroth interface to the froth phase and the transfer of the entrained particles in the froth phase to the concentrate 7. The rst step of entrainment is via (i) hydraulic boundary layers surrounding air bubbles 8, (ii) the wades of bubble clusters 9, and (iii) water entrapment by the continuous transport of bubbles into the froth layer 10. The water ow rate into the froth phase is inversely proportional to the bubble diameter 11. The reduced bubble size in saline water due to the inhibition of bubble coalescence 1214 may promote more water to ow into the froth phase and therefore higher particle entrainment. The presence of the froth phase in a otation cell provides certain time for the water and the entrained particles to drain back to the pulp phase before the froth enters the concentrate. The transport of gangue minerals in the froth phase is strongly affected by the structure of the froth and the bubble size. Small-bubbled and closely-knit froth is likely to enhance the entrainment of gangue minerals 15.It has been found experimentally that the amount of gangue minerals recovered is intimately related to the amount of water recovered 6. The relationship between the water recovery and gangue recovery is linear over most of the region of interest. When this linear relationship is extrapolated, it produces a zero intercept on the water recovery axis for very ne particles. The slope of the linear portion of the relationship increases with decreasing the particle size. It is often refer to as the degree of entrainment (ENT) which is normally calculated by the equation 16:where a is the mineral assay, m is the mass fraction, X is the solids concentration (% solids), subscripts i and j represent the particle size fraction and mineral, respectively, and superscripts p and c represent the pulp phase and the concentrate, respectively. Eq. (1) uses the water as a reference to dene the classication effect of the drainage of entrained particles in the froth phase. Savassi et al.17 predicted the following boundaries of ENT in relation to the particle size di (lm):These boundaries are consistent with the measurements in industry otation cells indicating that smaller particles correspond to greater ENT and the ENT is normally smaller than 1 due to the higher specic gravity and faster drainage of gangue minerals than water 6,7,16. However, Eq. (1) does not distinguish entrainment from physical entrapment between particles in the froth attached to air bubbles. From literature, physical entrapment occurs in three circumstances in mineral otation and may result in a higher recovery of gangue minerals and calculated ENT value than expected from the entrainment. Firstly, entrapment occurs when the thickness of the froth lamellae and Plateau borders reduces to a value similar to or less than the particle size 18. At such a condition, the free drainage of the particles may cease. Secondly, the otation of composite particles without complete liberation of gangue minerals from value minerals is another type of entrapment, contributing to the recovery of non-oating particles 16. Thirdly, the occlusion of gangue minerals within the ocs or aggregates of hydrophobic value minerals attributes to entrapment as well 19.In coal otation, aggregation among coal particles has been reported 19. The degree of aggregation increases as a function of hydrophobicity of the coal particles and the amount of the oily collector present in the system. Pawlik et al. 20 attributed the aggregation of hydrophobic coal particles to the hydrophobic forces which occur over a broad pH range, while the aggregation of hydrophilic coal particles to van der Waals interactions when the zeta potential values were near zero (e.g., around the iso-electrical point). Aggregation in coal otation means entrapment of mineral matter in the aggregates of coal particles. Polat et al. 21 observed that the primary size distribution of the coal sample was much greater in the otation cell as a result of aggregation compared to the size distribution of the same coal dispersed using chemical and mechanical dispersion methods, corresponding to entrapment of mineral matter and a higher ash recovery.In this study, the behaviour of mineral matter in coal otation using saline water in terms of entrainment and entrapment was examined. For a comparison, de-ionised water was also tested.2. Materials and methods2.1. Raw materialsA coal sample obtained from a coal mine was tested in this study. It is thermal coal with about 25 MJ/kg Caloric value, 0.4% sulphur content, 6% humidity and 15% ash content. XRD analysis of this sample is indicated in Table 1. The mineral matter includes quartz, kaolinite, calcite, ankerite, siderite, pyrite and bentonite minerals with bentonite minerals being predominant consisting of 9.1% of the sample. The concentrate of the amorphous phase is 86.8%. The combustible content of the coal is about 85%. The coal sample was crushed to a size of 2.36 mm before grinding and otation. De-ionised water and saline water were used. Saline water was made in the laboratory by adding certain amounts of a number of salts in 50 dm3 de-ionised water. The chemical composition of the saline water is shown in Table 2. Similar saline water was used previously in the otation of coal and produced signicantly different results to fresh water 22. The water was well mixed before the use to ensure similar concentrations of salts for each experiment. The de-ionised water used in this study has the resistivity of 35 X m. MIBC (Methyl Isobutyl Carbinol) and diesel, industrial grade, were used as frother and collector, respectively. They are widely used in the otation plants in Australia including the one where the coal sample was obtained.2.2. Grinding and otation100 g crushed sample was ground in a laboratory stainless steel rod mill at 33.3% solids to obtain 80% particles passing 75 lm. The size distribution of the mill discharge measured by a Laser Diffraction Malvern Mastersizer (Model No. MSX14) is shown in Fig. 1.Half of the particles after grinding were smaller than 30 lm. This matches the size of the otation feed in the plant where the coal sample was obtained. SEM analyses showed that mineral matter was liberated from coal particles after grinding. After grinding the pulp was transferred to a 1.5 dm3 JK Batch Flotation Cell and then conditioned with collector (240 g/t) and frother (160 g/t) at an agitation speed of 950 rpm. The solid percentage in the otation cell was about 6.5%. In otation, four concentrates were collected after cumulative times of 1, 2.5, 5, and 10 min. When de-ionised water was used, otation was operated at an air ow rate of 3.0 L/min at which normal otation was observed. However, when saline water was used, an air ow rate of 3.0 L/min caused signicant overow and normal otation was not possible. This reects the industry practice where otation is operated differently in fresh and saline water. In this study, the air ow rate was reduced to 1.6 L/min to ensure no overow in the otation using saline water, and therefore the behaviour of mineral matter in ne coal otation using de-ionised and saline water was compared under normal otation instead of exactly the same conditions. The otation froth was scraped every 15 s.The chosen water type, de-ionised or saline water was utilized in all stages of grinding and otation. When saline water was used,the pH during grinding and otation was constant, about 8.6, due to the buffer effect of the water. When de-ionized water was used,NaOH solutions were used to maintain pH at 8.6 during grinding and otation. Flotation concentrates and tailings were ltered,dried at 80 C, and weighed for analysis. For the ash analysis,10 g of dried sample from each product was rst ground using a mortar and pestle and then burned in an oven at 815 C for 2 h.The ash left over was weighed to calculate ash and combustible contents. This procedure to analyse ash and combustible contents was described elsewhere 22. The ash or combustible recovery in the otation concentrate was calculated as the percentage of the ash or combustible component in the otation feed.The combustible or ash recovery on a size-by-size basis was also obtained. Concentrate and tailing products were wet screened by using sieves of 106, 75, 53, 45, 38 and 20 lm. The combustible and ash recovery in each fraction was calculated.2.3. Froth analysisThe froth was measured by using VisioFroth software developed by Metso Minerals Cisa. The camera was set up above the otation cell and connected with a laptop. The measurement area was 11 cm 10 cm. The camera signals are relayed back via an ethernet cable and an optical bre to a central processing computer. When otation commenced, the camera recorded the froth every second automatically. The recorded images were then processed manually for calculating the bubble size and froth stability. The detailed procedure has been described elsewhere 23.2.4. Froth and pulp rheology measurementsA rotational viscometer (METTLER RM180) was used for froth and pulp rheology measurements. Froth rheology measurements were conducted in the otation cell directly when the froth bubble size was measured. The methodology and rationale of the in situ froth rheology measurement were described elsewhere 24. To measure the pulp rheology, the ash or coal suspension was conditioned in the otation cell following the otation procedure. Then 0.1 dm3 slurry was taken for the measurement. This viscometer employs concentric cylinder geometry with a rotating inner cylinder and a stationary outer cylinder. The inner cylinder has 14 different rotation speeds from 10 to 1000 rev/min corresponding to a shear-rate range of 41200 s1. The torque developed on the inner cylinder is directly related to the sample viscosity. The viscometer employs a computation program so measurement parameters such as shear rate, shear stress, viscosity, and torque are directly calculated. In this study, measurements were taken at varying rotational speeds. About 10 repeat readings at one rotational speed were recorded. The measurement was repeated from low to high rotation speeds and then from high to low rotation speeds. The mean was used for rheology calculation.3. Results and discussion3.1. FlotationFlotation was conducted in de-ionised water and saline water.The combustible recovery and ash recovery as a function of otation time are shown in Fig. 2. When de-ionised water was used, the combustible recovery and ash recovery were 58% and 32%,respectively, at the completion of 10 min of otation. The ash content in the nal concentrate product was about 9%. When the coal sample was oated in saline water, the combustible recovery was increased dramatically to 89% in the same otation time although the air ow rate during otation was reduced to avoid overow. The ash recovery was increased to 66% at the same time. The ash content in the nal concentrate product was about 26% when the coal sample was oated in saline water. Fig. 2 indicates that saline water increased coal otation compared to de-ionised water. This is consistent with the observation by all other researchers 15.However, saline water signicantly increased the otation of mineral matter as well resulting in the reduced quality of the nal concentrate in this study.Fig. 3 shows the combustible and ash recoveries on the size-by-size basis. In both de-ionised and saline water, the combustible or ash recovery was higher at the smaller size fraction. Compared to de-ionised water, saline water increased the combustible and ash recoveries in all size fractions. In mineral otation, in general, the otation of hydrophobic particles is lower in ne and coarse size fractions, but maximised in intermediate size fractions. This is because the bubbleparticle collision efciency is low for ne particles and bubbleparticle detachment efciency is high for coarse particles 25. The otation of gangue minerals is normally higher at smaller size fractions due to higher mechanical entrainment 6. However, in coal otation the exact relationship between the particle size and otation is complex and not well understood, mainly due to the aggregation of ne particles in otation 19. In this study, both combustible and ash recoveries were increased with a decrease in the particle size.It is known that dissolved ions behave like a frother in otation using saline water 2,4. Quinn et al. 26 indicated that in three-phase tests on a sulphide ore, the bubble size and froth overow rate were comparable between 0.4 M NaCl and 10 ppm MIBC. It is suspected that when the additional frother is added with saline water in otation, a more frother effect may be produced with a simultaneous increase in both combustible and ash recoveries.The properties of otation froth in de-ionised and saline water were investigated by the froth image analysis in this study.Fig. 4 shows the froth images before the otation was undertaken using de-ionised and saline water. As can be seen, the water type signicantly affected the froth structure. While saline water produced small, rounded and closely-knit bubbles, de-ionised water produced big and both rounded and elongated bubbles. This suggests that higher froth stability was produced in saline water. In fact, the froth stability directly calculated by VisioFroth software was about 20% in saline water, but 16% in de-ionised water. Kurniawan et al. 5 studied the froth properties in coal otation in MgCl2, NaCl, and NaClO3 solutions in the absence and presence of Dowfroth 250. They found that in the presence of Dowfroth 250 all the three salts produced more stable froth and smaller bubbles compared to fresh water and MgCl2 had the most pronounced effect 5. In this study, a number of salts were present in the saline water and MIBC instead of Dowfroth 250 was used as the frother,and the increased froth stability and reduced bubble size by saline water resulting in the improved combustible recovery were still evident. In addition, the froth with saline water was lighter, indicating more ash was recovered. This is consistent with the higher ash grade in the nal otation concentrate when saline water was used.Fig. 5 shows the mean bubble size as a function of otation time when de-ionised and saline water were used. With the otation time, the bubble size increased slightly in saline water but signicantly in de-ionised water. As a result, the difference in the bubble size was increased with otation time in de-ionised and saline water. In fact, the ash or combustible recovery in de-ionised and saline water was similar at the start of otation as shown in Fig. 2. However, with the otation time, the difference was increased. Apparently, the bubble size plays an important role in the otation of mineral matter and coal particles.To further examine the effect of bubble sizes, froth viscosity was measured as a function of the bubble size. The bubble size was adjusted by changing the frother dosage. The results are shown in Fig. 6. In both de-ionised and saline water, the froth viscosity increased with the decrease in the bubble size. However, the change of froth viscosity in saline water was more pronounced. At the same bubble size, froth viscosity was signicantly higher when saline water was used. Obviously, in addition to the bubble size, the water type, or electrolytes in the water affected the recovery of particles as well. As discussed previously, aggregation is an important phenomenon in ne coal otation, resulting in the increased combustible and ash recoveries. This may explain the high froth viscosity when saline water was used in this study. The increased combustible recovery by aggregation may be via the increased bubble-particle collision efciency due to the enlarged coal particle size 25, while the increased ash recovery by aggregation may be via the increased entrapment 19. Compared to de-ionised water, it seems that the increased ash recovery in saline water in this study is through the reduced bubble size which is associated with entrainment, and the increased aggregation which is associated with entrapment.3.2. Entrainment and entrapment analysisThe degree of entrainment (ENT) of ash in coal otation was calculated on a size-by-size basis using Eq. (1). Results are shown in Fig. 7. The calculated ash ENT was much greater in saline water than in de-ionised water for particles smaller than 38 lm. For example, for particles smaller than 20 lm, the calculated ash ENT was 1.6 in de-ionised water but 2.2 in saline water. For particles greater than 38 lm, the calculated ash ENT was relatively small and slightly greater in saline water than in de-ionised water. It is interesting to nd that the calculated ash ENT for particles smaller than 38 lm in both de-ionised and saline water was signicantly greater than 1, the maximum ENT of liberated gangue minerals in otation. Entrapment may attribute to the calculated ENT in coal otation.To evaluate the entrapment resulting from the aggregates in coal otation, pulp rheology measurements were performed. Firstly, the coal suspensions at 6.5% solids before otation using de-ionised and saline water were subjected to rheology measurements. Secondly, the mill discharges of coal samples were combusted. The resulting ashes were conditioned in the otation cell at 6.5% followed by rheology measurements. Results are shown in Fig. 8. Ash suspensions in the absence of coal particles show Newtonian behaviour, i.e., the viscosity of suspensions is independent of the shear rate. Saline water increased the viscosity slightly compared to de-ionised water. In general, shear stress of ash suspensions was low in both de-ionised and saline water. In contrast, coal suspensions exhibit non-Newtonian and shear-thinning behaviour, i.e. the viscosity of the suspensions decreases with an increase in the shear rate. Apparently, aggregates occurred in coal suspensions. Under shear, the large particle aggregates are separated into smaller units and, at very high shear, into individual particles. Such a process rheologically manifests itself as shear-thinning behaviour.In this study the pH was maintained at 8.6 at which surfaces of coal, and bentonite minerals (the major mineral matter) are negatively charged 25,2729, and electrostatic repulsions between them are expected. As a result, the aggregation in coal suspensions may be through the hydrophobic force between coal surfaces as demonstrated in other studies 19,20. Interestingly, saline water enhanced coal aggregation since the viscosity and shear stress increased signicantly compared to de-ionised water. It is well documented that electrolytes compress electrical double layers and therefore reduce the electrical double layer repulsive forces 27,30, which may enhance the aggregation in coal suspensions.It stands to reason that aggregates forming in coal otation promoted the entrapment of mineral matter. To quantify the recovery of mineral matter in coal otation through entrainment and entrapment, the otation of ash after the combustion was performed with the same conditions to the coal otation, and ENT was calculated. In the absence of coal particles, the recovery of mineral matter should be only through entrainment and the calculated ENT reects the true ash ENT in coal otation. Results are shown in Fig. 9. The ENT value was smaller than 1 across the size range. The smaller the particle size, the greater the entrainment in both de-ionised and saline water. Saline water increased the entrainment across the size range compared to de-ionised water and the increase in the entrainment was more pronounced for particles smaller than 38 lm.In this study, the degree of entrapment (ENP) in coal otation may be estimated by the equation:where ENTc is the calculated ENT in coal otation by Eq. (1) including both entrainment and entrapment as shown in Fig. 7 and ENTa is the calculated ENT in ash otation by Eq. (1) without the entrapment as shown in Fig. 9. The ENP values as a function of the size are shown in Fig. 9 as well. ENP was insignicant for particles greater than 38 in both de-ionised and saline water. For particles smaller than 38 lm, entrapment was signicant and even greater than ENT in both de-ionised and saline water. Compared to fresh water, saline water signicantly increased the entrapment of particles smaller than 38 lm. This is consistent with rheology measurements in Fig. 8 showing that saline water greatly increased the rheological properties of the coal suspension resulted from the increased aggregation of coal particles.It is interesting to nd that aggregates formed in the coal otation in this study were able to sustain the turbulence in themechanical otation cell and oated well, but could not sustain the wet sieving action so that all aggregates broke up and the particles ended up in their true discrete size fractions. While a similar phenomenon has also been observed in a number of otation systems, the reason is not clear. It seems that this discrepancy is associated with different energy dissipation in the otation cell. It is established that energy dissipation is high around the impeller to keep particles in suspension. This area is named Turbulent Zone.Between the turbulent zone and froth is the quiescent zone where energy dissipation is insignicant and a quiescent pulpfroth interface is maintained 31,32. It is suspected that coal particle aggregates in this study may be dispersed in the turbulent zone but reform in the quiescent zone entering the nal otation concentrate.4. ConclusionsIn coal otation, the recovery of mineral matter may be attributed to two mechanisms: entrainment between air bubbles transported to the concentrate through pulp and froth phases and entrapment in aggregates of coal particles.In this study, saline water increased combustible recovery but also ash recovery compared to de-ionised water. While saline water may increase the true otation, entrainment and entrapment were increased as well. In both de-ionised and saline water,entrainment was increased with a decrease in the particle size. Saline water increased the entrainment across the size range but the increase was more signicant for particles smaller than 38 lm.Entrapment played a more important role than entrainment in recovering mineral matter smaller than 38 lm in coal otation in this study. Saline water signicantly increased the entrapment due to the enhanced aggregation of coal particles.AcknowledgementsThe authors greatly appreciate nancial support from ACARP (Australian Coal Association Research Program), BHP Billiton Mitsubishi Alliance and Xstrata Coal as well as discussions and suggestions from Frank Mercuri and John Gartlan from Xstrata Coal, Ian Brake, Ben Cronin and Susan Watkins from BHP Billiton Mitsubishi Alliance and Xiaofeng Zheng from MMG Management Pty Ltd.References1 Yoon R, Sabey J. Coal otation in inorganic salt solution. In: Botsaris G, Glazman Y, editors. Interfacial phenomena in coal technology, New York: M. Dekker; 1989, p. 87114. 2 Yoon R. 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J Fluid Mech 1987;175:53755.2 中文译文在细煤浮选中使用盐水时矿物质的表现化工学院，昆士兰大学，圣卢西亚，布里斯班，昆士兰州 4072，澳大利亚重点盐水提高了煤炭浮选中矿物质的回收夹带的增多对细粒更显著在去离子的盐水中捕收剂扮演了更重要的角色盐水明显地提升了对细矿物质的捕收盐水加强了颗粒与夹带的聚合文章信息文章历史：2012年12月8号收到2013年1月6号收到修改2013年1月15号公认2013年1月29号网上可获得关键词：煤炭浮选，盐水，矿物质，夹带，捕收摘要在本次研究中，调查的是煤炭浮选中使用盐水时矿物质的表现。为了做对比，并行的测试去离子水。结果表明，当增加可燃体回收率时，盐水增加了矿物质的回收率。通过计算煤样浮选时夹带和燃烧后灰分的程度，外加泡沫图像分析和泡沫与矿浆悬浮液流变学测量值，来测试煤炭浮选中矿物质的夹带与捕收。相对于去离子水，盐水增加了所有尺寸的夹带，夹带的增多对小于38m颗粒的作用更显著。但是在不管是去离子水或是盐水的煤炭浮选中，捕收剂在回收矿物质时都扮演着至关重要的角色。盐水通过增强煤粒的聚合来增加捕收。1、 介绍在澳大利亚，煤炭开采是个重要的产业，它提供的煤炭产生了澳大利亚85%的电力。澳大利亚开采的煤炭有54%是出口的，大多数出口到东亚。在过去的几年里，由于对矿山可能排入当地河道网中的盐水有了严格政策，因此全澳大利亚的煤炭准备工厂使用的水质有了明显的改变。结果，大多数的煤矿引进了水再使用作为常见的实践。增加了水再使用的后果之一就是现场随后是浮选中水的盐分伴随着增长。现已经进行了不少研究来探究用盐水浮选。通常而言，与淡水相比，盐水增加了可燃物的回收。但是，这些研究都没有考虑到用盐水浮选中矿物质的表现。随着煤炭资源的消耗，越来越多的低级和难选的煤藏正在被发掘，盐水在浮选中矿物质的回收中扮演的角色也变得重要起来。众所周知，颗粒通过浮选来回收是真浮选和力学夹带共同作用的结果。在矿物浮选中，固体颗粒矿浆中加入捕收剂使得精矿变得疏水而使得矸石变得亲水。然后将空气注到矿浆中形成气泡与颗粒接触。疏水的颗粒趋于附着到气泡上，然后气泡颗粒聚合物来到矿浆顶部的矿浆泡沫界面处，最终作为精煤泥液进入流水槽。这一过程被称为真浮选。但是，当颗粒被气泡间的间隙水膜拖动时产生的力学夹带是与真浮选并行产生的，尤其对细粒来说也是矸石的初级回收原理。由于不可选择的本质和矸石在矿石中比较丰富的事实，通过夹带回收或许会对富集等级产生不利的影响。浮选中的夹带被认为是一个两步的过程，包括了在矿浆-泡沫界面下方、矿浆顶部区域的悬浮固体转移到泡沫阶段和泡沫阶段被夹带的颗粒转移到浓缩液。夹带的第一步经由包围在气泡的水力边界层、气泡群涉水区和连续将气泡转送到泡沫层的水捕收区。水流入泡沫区的流量与气泡的直径成反比。由于对气泡合并的抑制在盐水中减少气泡尺寸可能促进更多的水流入泡沫区，因此更多的颗粒被夹带。浮选室中泡沫区的存在为水和夹带的颗粒提供了足够的时间在进入浓缩液前流回矿浆区。在泡沫区矸石矿的转移很大程度地被泡沫结构和气泡尺寸影响。小气泡和紧密相连的泡沫很可能增强矸石矿的夹带。实验上已经表明矸石回收量与水回收量密切相关。在大多精煤区域阶段上，水回收率和矸石回收率呈线性关系。当这种线性关系被推测出，那么在水回收率轴上对超细颗粒产生了零截距。关系直线部分的斜率随着颗粒尺寸的下降而上升。它经常指的是夹带度，通常由下式计算而来：其中a表示矿物灰分，m是质量分数，X是固体浓度（%固体），下标i和j分别代表颗粒尺寸分数和矿物，上标p和c分别代表矿浆区和浓缩区。公式（1）使用水作为参照物来确定泡沫区夹带颗粒排出的分级效果。Savassi等人预测了ENT关于颗粒尺寸di（m）：这个界限与工业浮选室中的测量值是一致的，表明更小的颗粒造成更大的ENT并且由于更高的比重和矸石比水排出更快所以ENT通常小于1。但是，公式（1）并不能区分泡沫区中附着在气泡上的颗粒间的物理包容造成的夹带。从文献中可知，物理包容发生在浮选中的三种情况下，并导致矸石回收率和计算所得的ENT值大于预期的夹带。第一，诱捕发生在泡沫层的厚度和普拉特奥边界小于颗粒尺寸。在这种情况下，颗粒的自由排出将会停止。第二，矸石没有完全从精矿中分离的复合粒子浮选室另一种捕收，导致非浮动颗粒的回收。第三，疏水精矿中絮团和凝结中矸石矿物的闭塞也会导致诱捕。在煤炭浮选中，煤粒间的聚合已经报道过了。聚集程度的增加是煤炭疏水性和在浮选系统中出现油性捕收剂共同作用的结果。Pawlik等人当电动势值接近零时（如在等电势点附近）将疏水煤粒的聚合归因于发生在广pH值范围的疏水力的作用，而将亲水煤粒的聚合归因于范德华相互作用。煤炭浮选中的凝聚意味着对煤炭聚集体中的矿物进行捕收。Polat等人注意到，由于相同粒度分布的煤样使用化学和机械弥散方法使分散的煤粒聚合的结果，使得煤样的初级粒度分布比浮选室中的大的多，与矿物的诱捕和高灰回收相一致。在本次研究中，调查在夹带和诱捕方面使用盐水时浮选中矿物的表现。2、 材料和方法2.1 原料在本次研究中，测试从某一煤矿中获得的煤样。这是一种具有25MJ/kg热值、0.4%硫分、6%水分和15%灰分的发电煤。该样品的XRD分析在表一中有明细。矿物质包括石英、高岭石、方解石、铁白云石、陨铁、黄铁矿和组成9.1%样品的膨润土。无晶相成分占有86.8%。煤炭可燃体含量约为85%。在研磨和浮选前，煤样先破碎到-2.36mm。使用去离子水和盐水。在实验室中，向50dm3的去离子水中加入一定量的盐分从而制成盐水。盐水中的化学成分在表2中显示出。盐水预先在煤炭浮选中使用，并且明显地产生了与淡水不同的结果。水在使用前就搅拌均匀，保证了在每个实验中盐的浓度相似。在研究中使用的去离子水有35欧姆的电阻。工业级甲基异丁基甲醇和柴油分别作为起泡剂和捕收剂。它们广泛的在澳大利亚的浮选工厂中使用，也包括此次的煤样。2.2 磨碎和浮选100g破碎的煤样放入实验室的棒磨机中研磨，将1/3的固体物研磨使得到的80%颗粒力度小于75m。棒磨机得出的粒度分布由莫尔文激光衍射粒度分析仪测出（型号NO.MSX14），如图1。研磨后一半的颗粒小于30m。这与获得煤样的工厂供给入浮选中的相符合。扫描电镜分析表明矿物质在研磨后从煤粒中释放出来。研磨后，矿浆转入到一个15dm3的JK Batch浮选室中，然后加入捕收剂（240g/t）和起泡剂（160g/t）并在每分钟950转的速度下搅拌。浮选室中固体百分比约为6.5%。浮选中，在累计1分钟、2.5分钟、5分钟和10分钟后，各取1分精煤泥。当使用去离子水时，浮选在进气量3.0L/min下进行，这时能观测到正常的浮选。当使用盐水时，3.0L/