球磨机节能降耗新途径机理及应用研究

【作者】 罗春梅；

【导师】 段希祥；

【作者基本信息】 昆明理工大学 ， 矿物加工工程， 2009， 博士

【摘要】 矿产资源是国民经济建设与社会发展的物质基础,现阶段,我国95%以上的能源、80%以上的工业原料、70%以上的农业生产资料都来源于矿产资源,30%以上的农业用水和饮用水来自属于矿产资源范畴的地下水。可以说,没有矿产资源持续稳定的供应,就没有现代经济与社会的健康发展。然而,在矿产资源的开发利用过程中需要消耗大量的能量。金属矿的采矿、选矿及冶炼消耗的能耗高达全国总能耗的15%以上。矿山的能耗占35-50%左右,冶金的能耗50-65%左右,矿山采选企业中,采矿耗能1/3,选矿耗能2/3,而选矿厂中,磨矿能耗又占全厂的50%,即占矿山采选的1/3。因此,在矿产资源的开发利用过程中,我国选矿厂特别是其碎矿磨矿阶段面临着节能降耗的艰巨任务。球磨机从诞生到工业应用一百多年的历史还说明,在吨位巨大及价廉的矿料磨碎中,目前及今后相当长的时期内,球磨机还将是一种不可替代的重要磨碎设备。因此,研究新的球磨技术,降低球磨机磨矿能耗对实现“能源开发与节能并重”的战略任务具有现实意义。磨碎过程是一个功能转变过程。磨碎过程中磨机输入的功率大部分转变为磨碎损失功,转变为有用功的能量很少。钢球对矿粒的破碎作用具有随机性,球磨机的磨矿过程是一个随机过程,磨碎概率很低,碎矿过程损失的能量大。由此可见,破碎概率低及破碎损失功大是球磨机能耗高的主要原因,节能的重点应放在如何提高矿物破碎概率及介质能量利用率两方面。因此,论文围绕着提高矿物的破碎概率及介质能量的利用率两个目的,从采用磨矿新技术使球径精确,装补球科学,介质形状适宜三个方面阐述粗磨机和细磨机实现节能降耗的机理。粗磨的给矿粒度范围宽,破碎比大。需要加多种钢球,故在粗磨过程中不仅需要精确地选择钢球尺寸以保证各级别钢球尺寸的精确,还要保证各级别球径的科学配比。因此,针对粗磨工艺的特点及对介质的要求,在粗磨段采用了精确化装补球方法的磨矿新技术。精确化装补球方法的研究内容主要有三个方面：(1)单级别球径的精确；(2)整体球荷精确；(3)补球精确。在磨矿过程中,矿粒破碎的概率取决于钢球碰到矿粒的概率(碰撞概率)及钢球与矿粒碰撞后发生破碎的概率(破碎概率),破碎矿粒的碰撞概率越高,破碎概率才可能越高,但只有钢球携带的能量足够时,才能使矿粒破碎。因此,矿粒要有高的破碎概率则必须有高的碰撞概率及钢球携带足够的能量。研究证明,只有在球径精确及配比科学的情况下,矿粒的破碎概率也才最高,破碎损失的能量减少,钢球能量的利用率提高,介质的消耗亦下降,因介质消耗与能耗几乎成正比。磨矿过程既是一个功能转变的过程,也是一个能量转移的过程。钢球携带的能量除了对矿石做功转变为矿块的变形能、裂纹形成和扩展的能以及形成新生的表面能外,还会因物料、磨矿介质之间的摩擦、振动被消耗掉。因此,钢球携带的能量E主要分为两部分：对矿块的破碎功W有,以其它形式损失的能量W损。E=W有+W损,当输入能量E不变时,W损减少了,W有就增大,则钢球能量的利用率η=W有/E×100%也就提高,介质的消耗亦降低。W有取决于钢球对矿粒的破碎概率。对一定粒度的一组矿粒群来说,钢球对矿粒的破碎概率除取决于钢球的打击次数及表面积外,还取决于钢球携带的能量是否足够。并且在提高η的同时,还要兼顾磨矿效果(即能量的有效利用),如果钢球传递给矿粒的能量W有使不需要破碎的矿粒破碎,形成不必要破碎或无效破碎,浪费了能量,而需要破碎的矿粒却没有破碎,造成磨矿产品中粗粒级和细粒级均过多,不仅浪费了能量而且产品粒度组成特性不好及解离度不高,违背了磨矿的目的及任务。因此,磨矿过程中在降低能耗及提高介质能量的利用率的同时,还要兼顾磨矿效果,也即能量的有效利用,实现矿粒破碎能量与有效破碎能量的最大化,也即实现介质能量转移的最大化与有效性。钢球转移给矿粒的能量是使矿粒发生破碎,可选择合适的破碎功耗学说的计算进行相对比较计算,计算结果表明：在装载量一定的情况下,球径愈大,个数愈少,打击次数也愈少,研磨面积也小,打着的易造成过粉碎,打不着的则形成粗粒级多,产品特性不好,故破碎的效率不高,能量的利用率不高。相反,球径越小,个数虽多,打击次数也多,研磨面积也大,但矿粒的有效破碎能量利用并不高,因为任何矿粒的破碎均需要达到一定的能量密度,过小的球携带的能量小,与矿粒相碰时并不能使矿粒破碎。只有在精确的球径及科学的配比下才能实现矿粒破碎能量与有效破碎能量的最大化,降低磨矿能耗,提高磨矿产品质量。球径精确时的钢球能量利用率比过大球径高28%。精确化装补球方案的钢球能量利用率比现厂过大方案高9.15%。矿物的破碎功耗及磨矿效果表明：矿粒发生破碎的概率不仅考虑了能量传递的最大化,还考虑了能量传递过程中使矿物破碎的有效性。因此,在磨矿过程中,不仅可以用矿粒发生破碎的破碎概率判断磨矿效果的好坏,还可以用来判断磨矿方法是否具有节能降耗的效果。在球径偏大的我国现厂磨机中钢球的球径由过大调整为精确后,打击力减小不仅使钢球的磨损速度减慢,亦使消耗减少。球径精确后,磨内的球径减小,磨内的钢球滑动显著减弱,用于克服滑动的功率减少,最终使磨机消耗的绝对功率下降,即绝对电耗下降。因此,球径的精确化提高了矿物破碎概率,磨机的生产率,并提高了能量利用率,使吨矿电耗相对降低,球径的精确使磨内钢球滑动减弱,磨机的绝对功率下降。相对下降与绝对下降的双重作用,实现了磨机的显著节能降耗。针对细磨作业特殊的工艺特征,细磨作业采用铸铁段取代传统的钢球。细磨作业用铸铁段代替钢球能实现能量转移的最大化和有效性,不仅能提高磨矿产品的质量,还能降低介质的消耗。由于铸铁段容易绕其轴向转动,而且由于其形状的特殊性,在磨机内翻动时难度大,介质间的滑动减弱。因此,细磨作业用铸铁段取代钢球后,磨内的介质滑动减弱,这种现象比采用小钢球时显著,故磨机消耗的绝对功率显著下降,即绝对电耗显著下降,进而实现细磨机的显著节能效果。生产率提高使得吨矿介质耗相对下降,冲击力减小则使机械磨损减轻,绝对耗量下降,相对下降与绝对下降的双重作用致使磨矿介质消耗显著下降。磨矿新技术先后在云锡公司、云铜集团各矿业公司、金川公司及蒙自矿冶公司等10多个矿山公司中进行过工业试验及应用,均取得了显著的节能降耗效果,并产生了显著的经济效益。磨矿新技术在不同的矿石类型(锡铜共生矿、硫化镍矿、铅锌矿、铜矿)及不同的磨矿流程(一段磨矿流程、标准两段磨矿流程、非标准两段磨矿流程)的应用中均取得了显著的节能降耗效果,电耗下降20-40%,介质消耗下降10-30%。证明了磨矿新技术在选矿厂节能降耗的应用中的广泛性、成熟性及可靠性。若全国60%的矿山企业采用磨矿新技术,据测算将每年节省电耗40多亿度,节省钢球消耗13.5万吨。说明了磨矿新技术是一种值得大力推广和应用的新技术,并为选矿厂的节能降耗开辟了新途径。更多还原

【Abstract】 The mineral resource is material base of the national economy construction and the social development. The present stage, in our country,95% above energy, 80% above industrial raw material,70% above agricultural production originates from the mineral resource,30% above agricultural water and the tap water stems from the ground water which belong to the category of mineral resource. It can be said that there is not the revising stable supply of the mineral resource, there is also not the healthy development of the modern economy and society. However, the mineral resource’s development use need consume great energy. The energy consumption, mining、mineral processing and smelting of metalliferous ore, reaches as high as above 15% of the national total energy consumption. The mine energy consumption accounts for about 35-50%, the metallurgy energy consumption is about 50-65%, in the mining and processing enterprise, mining consumes energy 1/3, the mineral processing consumes energy 2/3, and in the mineral processing plant, the grinding energy consumption, occupies 50% of the entire factory’s, is 1/3 of the mining and processing enterprise’s. Therefore, in process of mineral resource’s development use, specially crushing and grinding will be facing the arduous task of saving energy and reducing consumption. The ball mill also explained from the birth to the industrial application more than 100 years history, in mineral grinding of the giant tonnage and the low-priced, at present and in the next quite long time, the ball mill also will be one kind of unreplaceable important grinding equipment. So studying new ball grinding technology reduces grinding energy consumption of the ball mill, this have the practical significance to realize "the energy development and saving".The grinding course is a function transformation. In the course, the input’s power of grinding machine transforms largely the grinding loss merit, and very few for the useful energy. The steel ball has randomness to crush ore grain, grinding process of ball mill is a stochastic process, crushing probability is low, and the broken ore process loses the big energy. Thus it can be seen, the primary cause of high energy consumption of the ball mill is big the losing merit and low the crushing probability, saving energy should pay attention to two aspects, which how to enhance crushing probability of the mineral and raise crushing efficiency of the medium. Therefore, the paper, revolves two goals that enhance utilization ratio of the medium energy and crushing probability of the mineral, expounds coarse mill and fine mill to realize mechanism of saving energy and reducing consumption by three aspects that use the new grinding technology make ball medium accuracy、ball-load-addition science、suitable medium shape.The feeding size range of coarse grinding is wide, broken ratio is big. It need add many kinds of steel balls, thus in the coarse grinding process not only it need choose precisely steel ball size to guarantee precise steel ball size of various grades in the coarse grinding process, but also to guarantee the scientific allocated proportion of various ball diameter. Therefore, in view of characteristic of coarse grinding craft and the medium request, the new grinding technology of accurate ball-load-addition method was adopted in the coarse grinding section. The research content of accurate ball load-addition method have three aspects:(1) single ball diameter is precise; (2) overall ball is precise;(3) ball addition is precise. In the grinding process, the comminution probability of ore grain is decided the probability of the steel ball bumping into ore grain (collision probability) and after happening comminution (comminution probability), collision probability is higher, comminution probability is only then higher. But only the steel ball carries enough energy, the ore grain is comminuted. Only in the situation of precise ball diameter and science ball-load-addition, comminution probability is biggest, the stave loss’s energy reduce, the energy utilization ration of steel ball enhance, the medium consumption also drops, because the medium consumption and the energy consumption are proportional nearly.The grinding course is a function transformation, is also an energy transfer process. The energy which steel ball carries, besides transforms into the ore’s deformation energy, crack forming and expansion energy and the newborn surface energy, but because between the material, the grinding medium friction, the vibration was consumed. Therefore, The energy E which steel ball carries was divided into two parts:to the ore block acting W有, the energy which loses by other formsW损,E=W有+W损,when input energy E is invariable,W损reduces,W有will increases, then the energy utilization ration of steel ballη=W有/E×100% is enhanced, the medium consumption will also reduce.W有is decided comminution probability of steel ball bumping into ore grain. To a group ore grain of certain granularity, the collision probability of steel ball bumping into ore grain is decided by attacking times and the surface area of steel ball. Duringηenhancement, the grinding effect should be paid close attention(the energy uses effectively), if the energy that the steel ball transmits ore grain make ore grain break not to need, form nonessential stave or invalid stave, but needs to break ore grain actually not stave, creates the coarse grade and the thin grade excessively are many in the grinding product, not only the energy has be wasted, and the degree of dissociation are not high, the grinding goal and duty were violated. So During enhancing energy utilization ration of media and reducing energy consumption in grinding process, the grinding effect should be paid close attention, realizes maximization of ore grain comminution energy and effective comminution energy, also namely realizes the medium energy transfer maximization and the validity.The energy of the steel ball transfer ore grain make the ore grain to occur comminution, may choose the appropriate inferable formula of comminution power loss theory to calculate, The computed result indicated:In loading certain situation, the ball diameter was bigger, the number was less, steel ball, attacked ore grain number of times less, the attrition area was also small, hitted ore grain created easily the excessive comminution, not hitted the coarse grade were many, the product characteristic was not good, comminution efficiency was not high, energy utilization ration was not high. On the contrary, the ball diameter was smaller, the number was more, steel ball attacked less ore grain number of times more, the attrition area was also bigger, but the effective comminution energy use of ore grain was not also high, because any ore comminution need achieve certain energy density. Only when ball diameter was precise and ball allocated proportion was science, comminution energy of ore grain effective comminution energy would had realized maximization, the grinding product quality was improved, and the grinding energy consumption was reduced. From energy utilization ration of steel ball, precise ball diameter was higher than 28% of oversized ball diameter’s, accurate ball-load-addition plan was higher than 9.15% of the present factory’s. The comminution power loss of mineral and the grinding effect showed:the event quantity of ore grain comminution not only considered maximization of energy transfer, but also had considered the mineral comminution validity in the energy transfer process. Therefore, in grinding process we not only may use the event quantity of ore grain comminution to judge grinding effect quality, but may also to judge the grinding method whether to have the effect of saving energy and reducing consumption. After ball diameter adjusted precise from oversized,impacting strength reduced, the attrition speed of steel ball reduced, the consumption quantity decreased, After ball diameter precise, the biggest diameter reduced in mills, the glide of steel ball weakened, the power of overcoming the glide reduced, the grinding machine consumed the absolute power to drop finally, namely absolute electric quantity dropped. The dual function of relative drop and absolute drop realized saving energy and reducing consumption of ball mill.In view of special craft characteristic of the fine grinding work, the fine grinding work adopted the iron section to substitute tradition steel ball. The fine grinding work replaced the steel ball with the iron section, to be able to realize the energy transfer maximization and the validity, not only he quality of grinding product could be enhanced, but also the medium consumption could be reduced. Because the iron section is easy to revolve its axial rotation, moreover as a result of its shape’s particularity, rotation is difficult in the mill, glide between the medium is weakened. Therefore, after fine grinding work replaced steel ball with the iron section, in mill the medium glide was weakened, this phenomenon was more remarkable than the small steel ball’s, the absolute power of the mill dropped, the absolute electric quantity obviously dropped, then the remarkable saving energy effect of fine mill was realized. The productivity enhancement caused the relative drop of medium consume, the impulse reduced, then caused the machinery attrition to reduce, the absolute consumption failed down. The dual function of relative drop and absolute drop caused remarkable drop of medium consumption. The new grinding technology has carried on the industrial test and the application in Yunnan Tin company、Yunnan copper company、Jinchuan Corporation and Mengze Mining and metallurgy Company and so on more than 10 mine companies, this company have obtained the remarkable the effect of saving energy and reducing consumption, and has had the remarkable economic efficiency. the new grinding technology obtained the remarkable effect of saving energy and reducing consumption in the application of different ore type (Tin copper paragenetic mineral, sulphur-nickel ore, lead-zinc mine, copper mine) and different grinding flow (a section grinding flow, standard two section grinding flow, non-standard two section grinding flow), the electricity consumes dropped 20～40%, the medium consumption dropped 10～30%. It had proven universality, maturation and reliability of the new grinding technology in application of saving energy and reducing consumption of mineral processing plant. If 60% mine enterprise of the national, according to reckoning the electricity consumes will save above 4,000,000,000 kWh every year, the steel ball consumption will savel35,000 tons every year. It explained the new grinding technology is worth vigorously promoting and the application new technology, and opened the new way for saving energy and reducing consumption of mineral processing plant.更多还原