多宝山铜矿石高压电脉冲破碎预处理试验研究

通过对比高压电脉冲破碎和机械破碎对多宝山铜矿石性质和浮选指标的影响，探索了高压电脉冲破碎预处理对矿石的促进解离、预弱化和预富集等作用效果。采用自制高压电脉冲处理系统在140 kV下对26.5~31.5 mm粒级多宝山铜矿石进行了预处理，并与同条件下的机械破碎产品对比。分别测定了高压电脉冲破碎产品和机械破碎对比样品的硬度指标A×b值、邦德球磨功指数、Cu品位分布、单体解离度和可浮性。结果表明，相比机械破碎产品，高压电脉冲破碎产品的硬度指标A×b值提高了33.9%~39.8%，邦德球磨功指数降低了3.6 kWh/t；高压电脉冲破碎产品的Cu品位随粒度减小而快速增大，能够将69.2%的Cu元素预富集到产率为36.1%的-13.2 mm粒级破碎产品中；通过促进矿物单体解离，高压电脉冲破碎能够将Cu的浮选回收率提高2.33个百分点，精矿铜品位提高约1个百分点。试验结果可以为低品位铜矿石的高效低耗回收提供参考。     

给料粒度及产品粒度对其邦德球磨功指数的影响

邦德标准球磨功指数测定时要求的给料粒度为-3.2 mm,这在某些情况下很难获得,因此,研究邦德标准球磨功指数与待测定物料粒度之间的关系就显得尤为必要,这对拓宽邦德球磨功指数的应用范围,特别是对选矿厂二段磨机和再磨磨机的精确设计及计算起到重要的理论指导作用。以均质物料石英和非均质物料铁矿石为试验物料,采用邦德功指数测定方法,研究了邦德标准球磨功指数随给料粒度及产品粒度的变化规律,并建立了邦德功指数与给料粒度、产品粒度之间关系的数学模型。试验结果表明:在试验控制筛孔尺寸范围内,随控制筛孔尺寸变小,邦德球磨功指数基本呈现增大的趋势,且石英增大的幅度大于铁矿石增大的幅度;邦德球磨功指数与控制筛孔尺寸(μm)之间的关系可用二次函数关系式描述;给料粒度越细,磨矿循环达到平衡时其产品粒度(P80)越粗,但当筛孔尺寸小到一定程度时,产品粒度变化不明显;无论是均质物料石英还是非均质物料铁矿石,邦德球磨功指数随给料粒度的变化趋势相同,二者之间呈指数函数关系;均质物料石英的邦德标准球磨功指数适用范围为给料粒度1.7~3.2 mm,非均质物料铁矿石的适用范围为给料粒度0.9~3.2 mm,前者较窄,后者较宽,小于上述范围,则需对测定结果进行修正。     

Procedure for determination of ball Bond work index in the commercial operations

The Bond ball mill grindability test is run in a laboratory until a circulating load of 250% is developed. It provides the Bond Ball Mill Work Index which expresses the resistance of material to ball milling. This happens after 7–10 grinding cycles, which shows that the procedure is a lengthy and complex one and is therefore susceptible to procedural errors. Starting from the first-order grinding kinetics defined by means of the Bond ball mill, this paper discusses a simplified procedure for a rapid determination of the work index by just two grinding tests. The applicability of the simplified procedure has been proved on samples of copper and Iron ores that are located in Iran. The values obtained by this procedure do not differ by more than 7% from those obtained in the standard Bond test.     

破碎方式对冀东磁铁矿石微裂纹特性的影响

为考察矿石不同破碎方式对破碎后所得产品颗粒内部微裂纹特性存在的差异,以冀东地区某磁铁矿石为研究对象,对高压辊磨和颚式破碎2种破碎方式所得产品进行对比,分析不同破碎产品的微裂纹差异,并通过Bond球磨功指数的测定,研究微裂纹特性对磨矿产品的影响。结果表明:矿石经高压辊磨机破碎后产生的晶内裂纹和解离裂纹数量均明显高于颚式破碎机破碎后产品,随着粒度逐渐降低,颗粒中微裂纹的长度、宽度以及数量均逐渐增加,同时产品颗粒表面的粗糙度也显著增加;高压辊磨破碎产品比常规破碎产品的Bond球磨功指数(目标粒度-0.15mm和-0.074 mm)分别降低了13.55%和14.14%,采用高压辊磨破碎可有效降低磨矿能耗;在相同磨矿细度条件下,微裂纹数量多的物料,细粒级中铁矿物的含量更多,同时粒度分布也更为合理,但增长趋势随着磨矿细度增加而逐渐减弱。试验结果可以为冀东磁铁矿石降低碎磨成本,实现降本增效提供理论依据。     

Optimisation of autogenous grinding

Batch tests in a 0.6m diameter mill were used to simulate fully autogenous primary and secondary grinding. Substantial improvements in primary mill capacity were obtained by modifying the mill contents to simulate crushing of small pebbles and recycle of the crushed material. Secondary grinding efficiency (as measured by kWh per ton finer than 75 microns or Work Index), was improved substantially by reducing the pebble size to 20/28mm. The process as a whole was optimised when crushed rock coarser than 4 mm was recycled to primary mill, as the small pebbles were most efficient with “sand”. The benefit of using small grinding media has been known for some time, but the high cost and rapid consumption of small steel balls makes their use uneconomical. However a plentiful supply of small pebbles is available from a primary mill. A further and unexpected improvement in power efficiency was obtained when pebble milling was performed at 92% of critical speed.     

齐选厂与东烧厂二次磨矿介质消耗研究

提出了按矿石性质、粒度要求、工艺设备不同进行磨矿介质消耗研究的新方法.在对齐大山和东鞍山铁矿石磨矿功指数及可磨度进行研究的基础上,计算分析了齐大山选矿厂与东鞍山烧结厂二次磨矿介质理论和实际的消耗及对比情况,指出相关磨矿作业应加强降低磨矿介质消耗的研究工作.     

单轴压缩条件下岩石声发射特性的实验研究

采用SDAES型数字声发射仪和岩石参数动态测试系统,对云南大红山铜矿2组岩石进行了单轴压缩条件下的声发射实验,研究岩石在单轴加载过程中声发射活动随时间和应力、变形等内在规律,比较2组岩石声发射规律的异同,在此基础上分析了岩石的破坏机理。实验结果表明：2组岩石声发射活动规律大体相同。除加载初期外,岩石声发射活动与试样体积变形间有较好的关联性,岩样中裂纹形成和原有裂纹扩展是造成岩石声发射活动与试样体积变形的主要原因。岩石破坏过程中岩石的声发射率和能率不完全一致,声发射能率的变化规律较声发射率表现得更加敏感,更适合用来预测岩石的破坏。     

Use of rock mechanical properties to predict the Bond crushing index

The crushing energy in mineral processing industry is usually determined by empirical Bond’s index, regardless of the mechanical properties of a rock. Although several attempts have been made to obtain the comminution energy based on theoretical approaches, it would be appropriate to examine this relation based on physical concept. In this study, with the purpose of correlating the strain energy of a rock to the corresponding energy estimated by Bond’s index, spherical and cubic shape specimens have been simulated during crushing process between two rigid jaws. The specimens are modeled as elasto-plastic medium considering Mohr–Coulomb failure criterion. To verify the obtained results, finite difference method is used to model the fracture behavior in four volcanic rocks. All possible stages that may occur in the processing zone of crushing cubic and spherical rocks are examined and the combination of crushing stages with the lowest and highest strain energies is calculated based on simulation using FLAC3D code. The obtained strain energies are in good agreement with those of Bond’s energy. During the size reduction process of hard volcanic rocks, although shear and tensile fracture occur simultaneously, the shear mode of fracture consumes a larger portion of the crushing energy.     

不同地应力条件下锚杆支护机制数值模拟分析

利用ANSYS有限元软件,编制开发了锚 以护设计计算机辅助设计系统（ANSYSBOLT）,分析了不同地应力条件下合理的锚杆支护结构,提出了在高水平应力条件下,巷道的破坏是扭曲变形破坏,应主要加固顶底板,控制巷道扭曲变形。     

邦德可磨度测定替代方法的研究进展

邦德可磨度被用于计算指定粉碎程度下的比能耗，进而辅助磨矿回路的设计与设备选型。其标准测定方法耗时耗力，且所得信息很有限。对此，业内提出了若干替代方法克服上述缺点。基于一阶磨矿动力学，马格达利诺维奇提出了用2次开路磨矿模拟邦德可磨度试验的终点状态，极大缩短了试验量，然而对软硬混合矿石效果不佳。列文认为可磨度试验中每转对应标准磨矿条件下的能耗应是定值，并由大量数据计算出其平均值；据此，可通过若干开路试验得到满足粉碎程度的转数，进而直接求得邦德功指数。在总量平衡模型的框架内，研究者们可通过闭路或开路的磨矿试验建立磨矿动力学模型，之后在计算机上模拟邦德可磨度试验，在作业要求变化时只需更新模拟条件而不必做新的试验。随着对岩石力学研究的深入，研究者们逐步探索可磨度/功指数与岩石力学性质的关系，提出了若干方法，以便在采场中就能预测矿石对磨矿环节的影响，该方向意义较大，且有进一步发展的空间。     

Impact work index prediction from continuum damage model of particle fracture

The traditional Bond work index proposed by F.C. Bond over 60 years ago is still today a useful tool for characterizing material crushability and grindability in the minerals industry. Although not as popular as the Bond ball mill or the Bond rod mill work indices, the impact work index, also called Bond crushability index, continues to be much used for crusher selection. The present work shows the application of a model that combines measurements of particle fracture energies and a parameter that characterizes material amenability to breakage by repeated impacts in the prediction of the Bond crushability index. Results show that a reasonably good agreement exists between measured and predicted results, as long as losses in the pendulum apparatus, used to determine the Bond crushability index, are taken into account in the simulations.     

Image based modeling of rock fragmentation

In the mineral extraction industry, comminution modeling is not only interested in maximum rock strength, but also, or much more, in the energy required to induce rock fracture and, most significantly, into the effect of energy application on the produced rock fragments size distribution. An additional aspect of rock breakage, specific to the mineral extraction industry, is the modeling of liberation of particular mineral grains from the host rock matrix. These aspects of rock behavior make comminution modeling a unique field of rock mechanics.From a traditional engineering point of view (mining and civil), rock samples are considered to be homogenous. Although the mechanical properties of individual minerals can vary significantly, the properties of the minerals and of the mineral boundaries interact randomly enough to assume that in the size of rock samples mechanical properties can be considered homogenous. However, from a comminution point of view, heterogeneity caused by a difference in the properties of minerals are crucial and therefore rock material, even in the scale of a few centimeters, should be considered as heterogeneous. The comminution response of such rock will be influenced by the textural parameters of the rock as well as mechanical properties of constitutive mineral grains.Image based numerical modeling is a useful tool for investigation of the pattern and dynamics of the rock breakage process. Its usefulness rests on the fact that a difficult step of building a faithful model of rock texture and composition, as a pre-requisite for modeling of rock breakage, is removed. Numerical modeling based on the use of classified digital image of the rock surface, could be particularly effective in the mineral extraction industry, where one of the key objectives is liberation of specific minerals, by providing inside view of mechanisms that are responsible for liberation of valuable minerals embedded into specific ore matrix.     

高压水射流破岩能量耗散与释放机制

从应力-应变角度建立的高压水射流破岩准则,其精确度取决于对屈服应力的表述,由于表达式中不含材料参数,不能精确计算高压水射流破岩参数,而从能量角度建立的岩石强度理论具有更好的适用性和准确性。开展了基于能量耗散和释放机制的高压水射流破岩机理,理论研究了自由射流段速度分布特征,分别计算了等速核区和射流边界层扩展区动能,建立了不同靶距处射流动能计算模型。高压水射流冲击破岩能量表征为冲蚀坑的形成和岩体的体积破坏;射流能量耗散于剪切面的扩展和滑动,储存弹性势能的释放导致岩体的整体体积破坏。根据岩石的统一能量屈服准则,建立了高压水射流破岩能量准则。通过砂岩、灰岩和花岗岩的单轴压缩应力-应变曲线得出3种岩石的材料参数,计算每种岩石的剪切应变能和体积应变能,得出射流破岩临界速度。根据高压水射流冲击破岩实验结果修正了考虑喷嘴流量系数的高压水射流破岩能量准则,该准则能够较为精确的计算射流破岩速度。且岩体的破坏形态证明从能量角度研究破岩机理更为适合。     

Generating a rock breakage process from sieve data

The sieve data obtained from laboratory rock breakage impact tests are used to infer the underlying probability distribution of fragment sizes by number. This enables one to generate an explicit population of fragments from an impact of specified energy. Such fragments are needed in simulations of mills that are based on the dynamics of individual particles.The method involves generating independent fragments from the number distribution and truncating the last fragment so that total fragment mass equals the mass of the parent rock. Fairly restrictive assumptions are made about fragment shape and density. Given these assumptions, the method is shown to be exact for a particular breakage process based on Poisson statistics. It is also shown to be asymptotically exact for a large number of fragments in a broad class of fragmentation processes. Examples of fragment populations are given.     

Ore particle breakage behaviour in a pilot scale high voltage pulse machine

SELFRAG AG has developed a flexible pilot scale Pre-Weakening Testing Station (PWTS) using high voltage pulses (HVP). This provides a unique opportunity to investigate the machine setting conditions on ore breakage behaviour. A joint campaign was undertaken by the Julius Kruttschnitt Mineral Research Centre and SELFRAG AG to investigate the breakage behaviour of two copper–gold ores and one iron ore in the PWTS. The effects of specific energy, pulse voltage, cumulative discharges, feed particle size and ore particle breakage pattern (body breakage or surface breakage) were investigated. The investigation revealed that the mass-specific energy of HVP was the most significant factor affecting the breakage behaviour in the PWTS. This effect was compounded with the effects of ore properties and particle size. Comparison between the PWTS and a laboratory HVP machine indicates that there is considerable scope for optimisation of HVP performance based on processing zone design.     

辽宁鞍本地区某铁矿废石碎磨特性研究

为解决废石堆存造成的一系列环境及安全问题,明确铁矿废石制备砂石骨料工艺流程,以辽宁鞍本地区某铁矿废石为例,在对其性质进行分析的基础上,开展了基于Bond球磨功指数试验与JK落重试验的碎磨特性参数研究。Bond球磨功指数试验结果显示,该铁矿废石Bond球磨功指数Wib为12.05 kWh/t。JK落重试验结果显示,该铁矿废石抗冲击粉碎模型为t10=71.25(1-e-0.52ECS) ,其中冲击粉碎参数A×b的值为37.05;磨蚀系数ta的值为0.17;相对密度为3.06。试验结果表明,该铁矿废石抗冲击粉碎能力属于硬范畴,抗磨蚀粉碎能力属于极硬范畴。结合上述试验结果,最终确定了该铁矿废石的生产设备与利用工艺。     

加卸荷对岩石弱化破坏的影响

在岩石试样的加卸荷试验的基础上,结合工程实际,研究了加卸荷对岩石弱化破坏的影响.研究表明,加卸荷可以造成岩石试样的破坏;在增加轴向应力或减小最小主应力的条件下,岩石试样的变形会随之增大;卸荷破坏时岩石的强度较加荷破坏时更低.     

劈石器破岩技术应用研究

介绍了几种矿岩大块二次破碎的基本方法,分析了劈石器破岩的基本原理及其主要特点,阐述了劈石器破岩的试验情况。研究和试验表明,劈石器是一种新型、实用、低成本的矿岩二次破碎设备,具有广阔的应用前景。     

邦德球磨功指数试验的影响因素

邦德球磨功指数是选矿厂碎磨流程设计和磨矿回路作业效率评价的重要依据。不同的商业化邦德球磨功指数试验流程中存在的钢球配比与磨机筒体结构的差异常常被忽略,这种差异会对邦德球磨功指数的测试结果造成明显的影响。入料粒度、产品粒度、矿石性质等因素均会对邦德球磨功指数的测试结果造成影响,在试验时需要充分考虑这些因素的影响。尽管如此,邦德球磨功指数仍然是一种方便和准确的测定矿石可磨性的标准方法。