An energy benchmarking model for mineral comminution

A method for determining the minimum practical energy for comminution was developed and is presented in this paper. An objective of the method was to determine experimentally the energy-breakage relationship for a wide size range in order to evaluate the energy performance of both crushing and grinding processes using one energy benchmarking value.Single-particle compression breakage, referred to in the field of comminution as one of the more efficient forms of mechanical comminution, was the basis for a test regimen to characterize the energy-breakage properties of ores. Existing models for impact breakage were found to be valid for single-particle compression breakage when used in a modified form. A key parameter of the adopted model, the threshold energy, was also investigated for three ore types and a range of particle sizes.The energy performance of comminution processes at a Canadian mining operation was determined by comparing the determined minimum practical energy, using the new method, with actual site specific energy requirements. In order to evaluate the energy performance of different crushing and grinding technologies, the proposed energy benchmarking method was used to compare the energy performance of alternative comminution flowsheets.     

The energy distribution theory of comminution specific surface energy,mill efficiency and distribution mode

The present paper is a partial theoretical approach to the comminution process. A general theory of comminution should consist of two parts, one that deals with the energy required to break mineral particles and another that examines how this energy is distributed to the particles generated after breakage. The present approach deals with the second part that examines how the energy invested for comminution is distributed to the mill product. It uses the generally accepted concept, which assumes that the useful part of comminution energy is consumed to create new surfaces and finds the relationship between a characteristic particle size of the mill product and the energy consumed for grinding. The paper introduces the concept of potential energy and provides the means to give a value to the energy state of a material produced by a specific type of equipment. The energy efficiency is also taken into consideration and is used to calculate the energy actually invested for comminution. The main conclusion is that the specific surface energy is a physical property of materials and can be used as a universal index characterizing their grindability, regardless of the mill type or the mill efficiency. The physical dimensions of this index are energy per unit surface area (J/m²) compared to energy per unit volume or unit mass, which are the dimensions of the indices proposed so far.     

基于矿物学特征的磁铁矿石破碎解离预测研究

为研究矿石矿物学特征对破碎后矿物解离程度的预测机制,以水厂铁矿沉积变质型磁铁矿石为研究对象,采用偏光显微镜观测矿石结构、构造与粒级组成,对比冲击破碎与二段磨矿产品的品位特征,分析磁铁矿石的破碎性质,预测矿石破碎后不同粒度范围下矿物颗粒的解离程度。结果表明,水厂铁矿磁铁矿石的结构构造简单,破碎过程中易产生沿晶断裂,冲击破碎至嵌布粒度的磁铁矿颗粒解离程度高于二段磨矿后磁铁矿颗粒的解离程度。矿石结构与构造特征可以反映矿石破碎与矿物解离的难易程度,通过分析磁铁矿石原矿矿物的粒级组成,可以有效预测矿石破碎后不同粒度范围内的矿物解离程度。研究结果丰富了矿石碎磨特性的分析方法,为矿山改进矿石加工工艺、实现节能增效提供了理论依据。     

Flowsheet considerations for optimal use of high pressure grinding rolls

High pressure grinding roll (“HPGR”) technology is very rapidly gaining a wide acceptance within the mineral processing industry. Benefits, including a superior energy efficiency and a lower overall operating cost of an HPGR based circuit compared to alternative technologies have been demonstrated at a number of operations throughout the world. Increasing numbers of units are presently being installed in the minerals industry world-wide. This trend is an excellent reflection of the confidence now placed in the technology by new and existing users.This paper summarizes basic principles of the equipment and of various options how to include an HPRG in the grinding circuit for most efficient use. Case studies demonstrate the application of HPGR’s in different grinding circuit set-ups and for the comminution of different ore types. Benefits of the options of open circuit grinding, closed circuit grinding incorporating wet and dry screening as well as the option of achieving a finer grind by recirculating part of the HPGR product using a mechanical splitter are discussed.From a processing point of view the effects of partial product recycle are detailed and some guidance for selection of cut size between HPGR and ball mill is provided.     

Research of iron ore grinding in a vertical-roller-mill

The total energy consumption for ore comminution will further increase within the next decades. One contribution to minimise the increase is to use more efficient comminution equipment. Vertical-roller-mills (VRM) are an energy-efficient alternative to conventional grinding technology. One reason is the dry in-bed grinding principle. Results of extensive test works with two types of magnetite iron ores in a Loesche VRM are presented here. Within these test works, mill parameters like grinding pressure, separator speed and dam ring height were varied, following a factorial design of the experiments. The effects of the grinding parameters on the liberation of valuable minerals are characterised using mineral liberation analysis (MLA). It is shown how the different mill parameters influence important performance values like energy consumption, production rate and mineral liberation. Via multiple regression analysis, an optimal parameter range can be modelled for both ore types. The parameter predictions have been successfully verified in practical test works.     

振动磨机磨制高浓度水煤浆的研究

振动磨机可成功地用于磨制高浓度水煤浆,能耗低,效率高。影响振动磨机工作的重要因素是振幅,浓度,球荷及添加剂。由于水煤浆的粘性很大,磨机内研磨作用减弱,因而以冲击破碎作用为主。     

高压辊磨机粉碎工艺国外应用进展与发展趋势

基于层压粉碎原理,高压辊磨机具有处理量大、能量利用率高、粉碎产品粒度细等特性,已经广泛应用 于冶金矿山领域,且节能降耗效果显著。 文章总结了开路粉碎、边料返回半闭路粉碎和筛分(包括干法筛分和湿法筛 分)全闭路粉碎三种粉碎工艺的选择依据。 结合高压辊磨机在金刚石解离、铁矿球团原料预处理、(半)自磨顽石破碎 和金属矿磨前粉碎领域的典型应用案例,重点阐述了高压辊磨机的粉碎工艺流程、设备型号、操作参数及应用效果。 不断提高粉碎效率、降低粉碎成本仍是高压辊磨机粉碎工艺的发展方向。 虽然多台高压辊磨机串联配置、高压辊磨 机与风力分级设备配置、高压辊磨机与搅拌磨机直接配置等新工艺发展不够成熟,但节能降耗优势明显,有望为冶金 矿山物料高效粉碎提供新的解决方案。     

碎磨工艺现状及发展趋势

碎磨工艺是后续选冶工艺的准备过程或准备作业,必须满足选冶工艺对矿石处理的粒度要求,使矿物充分地单体解离才能获得高质量的选冶产品和高指标。碎磨产品质量直接影响到选矿指标和生产成本,是选矿厂的重要组成部分。本文通过分析选矿厂碎磨工艺流程现状,指出了存在的主要问题:碎磨流程试验研究重视程度不足、建设投资和生产能耗高;噪音和粉尘大污染环境等。针对这些问题,探讨了碎磨工艺有效的应对措施,以满足选别对产品粒度更严格的要求,适应节能、环境、操作更苛刻的条件,并对未来碎磨工艺发展趋势进行了展望。     

What is required from DEM simulations to model breakage in mills?

It is quite common to encounter discrete element method (DEM) simulations of mills that present images of the motion of grinding media, summaries of tangential and normal forces, and mill power. The usefulness of this data is questioned, with respect to modelling breakage. This work presents hypotheses of how the DEM simulations can be used as input to comminution modelling, and this guides the data logging and analysis requirements. Techniques are proposed for collecting and using this data in a manner useful for predicting breakage in a comminution device. Individual particle impact histories of contact angle, force, and impulse are required to realistically model breakage. It is argued that the majority of breakage results from cumulative damage, thus it is essential to track individual particle histories to realistically predict the breakage product from a mill.     

高压辊磨机选型试验的研究现状

结合高压辊磨机中物料粉碎机理,介绍了影响高压辊磨机粉碎效果的关键因素,评述了高压辊磨机设备选型试验的研究现状。高压辊磨机粉碎物料的效果主要受物料性质、辊压机工作参数及粉碎工艺等的影响。通过小型及半工业型高压辊磨机粉碎试验能够为高压辊磨机的设备选型和流程设计提供依据,但试验过程相对复杂。颗粒床活塞压载试验和数学建模尽管能够对矿石料层粉碎的工作压力、比能耗、产品粒度分布等进行有效预测,但和高压辊磨机设备选型的经验公式一样均需要对其适用性进行验证。指出高压辊磨机未来的研究方向为粉碎过程中能量传递模型、矿石碎磨特性及对分选工艺影响等的理论基础研究,以及高压辊磨机在选矿流程中的数值模拟研究。     

Energy recovery potential in comminution processes

Comminution processes are cited as having an efficiency of less than 1%. Even if the efficiency of these processes could be increased to 5% as is suggested to be possible, the conclusion would remain that comminution processes are very inefficient with some 95% of the input energy lost to the environment as heat. This is an interesting observation as one could suggest that, although comminution systems are very inefficient in producing new surface energy, they should be very efficient in producing heat. On the other hand, high efficiency in generating heat might be off-set by a limit on the energy that can be recovered.In this paper, four issues will be addressed: heat generated in comminution, potential energy recovery, different means to increase energy recovery in comminution processes and avenues to possible implementation. It will close with a discussion of a number of issues surrounding energy recovery in comminution processes.     

多元线性回归在磨矿回路中的应用研究

球磨机是粉碎过程中应用最为广泛的磨矿设备，通过建立数学模型，优化了球磨机结构、工作条件、物料性质和磨矿性能之间关系，提高粉碎和磨矿效率，研究了多元线性回归在球磨机中的应用。     

铁矿石粉碎能耗合理分布模型的研究

按照系统能耗最低原则,研究了冀东鞍山式磁铁矿石粉碎过程包括爆破、破碎、磨矿作业作为一条作业线,构建了矿石粉碎过程各工艺环节能耗合理分布模型.运用该研究成果,对马兰庄铁矿的爆破、碎矿、磨矿等作业的能耗分布进行优化分配,适当提高能量利用率较高的爆破、碎矿作业的能耗,降低能量利用率较低的磨矿作业的能耗,使矿石粉碎总成本下降了4.01元/t(原矿),每年节省费用721.8万元,节能降耗效果显著.     

Estimating energy in grinding using DEM modelling

The latest state of the art on Discrete Element Method (DEM) and the increased computational power are capable of incorporating and resolving complex physics in comminution devices such as tumbling mills. A full 3D simulation providing a comprehensive prediction of bulk particle dynamics in a grinding mill is now possible using the latest DEM software tools.This paper explores the breakage environment in mills using DEM techniques, and how these techniques may be expanded to provide more useful data for mill and comminution device modelling. A campaign of DEM simulations were performed by varying the mill size and charge particle size distribution to explore and understand the breakage environment in mills using DEM techniques. Analysis of each mill was conducted through consideration of the total energy dissipation and the nature of the collision environment that leads to comminution.The DEM simulations show that the mill charge particle size distribution has a strong influence on the mill input power and on the way the energy is distributed across the charge. The smaller particles experience higher energies while the larger experience less, but this variation is strongly dependent on the mill size. The results also showed that the average particle collision energy increases with increasing mill size, whereas its distribution over particle size is strongly influenced by the mill content particle size distribution. The simulations also captured the energy distribution within different regions of the tumbling charge, with the toe impact region having higher impact energies and the bulk shear region having higher tangential energies. Regardless of the mill size most of the energy is consumed by the particles in the mid-size range, which has the highest percentage mass of the total charge distribution.     

Energy efficient comminution under high velocity impact fragmentation

In mining operations, comminution processes are responsible for most of the energy used during mineral recovery. Low fragmentation efficiency of comminution in the range of 1-2% (Tromans, 2008) occurs due to the quasi-static nature of the process which is typically accompanied by low impact velocities. Accurate estimation of efficiency requires a measurement system to account for fractal parameters such as surface roughness and fracture surface area. Continuum breakage models of single particles fail to estimate the actual stress transformation that affects bulk material during comminution. In order to study comminution in a dynamic regime at higher strain rates than those of conventional equipment, a compressed-air apparatus designed to launch a projectile at velocities as high as 450 m s⁻¹ has been developed to measure the quantitative nature of high-speed impacts on aggregated rock samples. A method to calculate the energy efficiency is also presented. The results of experiments conducted on three materials suggest the energy efficiency of rock breakage can be improved by two or three times under high velocity impact for the same energy input level. The paper reports an empirical model of impact velocity and energy input and discusses the advantages and limitations of this model.     

高压料床粉碎与盘式辊压破碎机

利用料床粉碎设备对坚硬的金属矿石进行粉磨,需要考虑三点:足够大的粉磨力是粉碎金属矿石的首要条件;经济可行的金属磨蚀量是设备能够推广应用的前提;连续稳定的料床是降低设备振动、提高设备寿命的重要措施。通过分析高压料床粉碎影响因素、盘式辊压破碎机结构特征和施力特征,总结出作为一种新型金属矿石粉磨设备,盘式辊压破碎机在料床稳定性、对坚硬矿石粉磨性和能量利用率方面的优势。     

云南某铜矿SABC碎磨流程能耗分布规律及能量基准评价研究

提高碎磨流程能量利用效率是降低碳排放的重要途径,而碎磨能耗分布规律研究与能量基准评价是提高能量利用效率的前提和基础。某大型铜矿SABC碎磨流程能耗分布规律研究结果表明,碎磨全流程比能耗为19.59kWh/t,半自磨机、球磨机、顽石破碎机的比能耗分别占全流程比能耗的36.76%、55.75%及0.83%;球磨机运行功率接近安装功率的93.40%,是限制碎磨系统产能进一步提升的瓶颈。以原矿代表性样品单颗粒冲击破碎试验为基础,建立了矿石粉碎模型,通过能量基准评价方法计算出SABC碎磨全流程理论最低粉碎能耗为8.96 kWh/t,分别对SABC碎磨全流程、半自磨+振动筛+顽石破碎作业、球磨与分级作业进行了能量基准评价,得出能量效率因子（BEF值）分别为2.19、1.71和2.60,进一步明确了提升球磨分级作业能量利用效率的必要性。能量基准评价研究为碎磨流程能量利用效率提供了统一、定量的评价指标,为碎磨全流程产能提升与节能降耗指明了优化方向。     

Application of process mineralogy as a tool in sustainable processing

The observed behaviours of mineral particles in mineral processing operations have been exploited in the past to model comminution and concentration processes. In this work this concept has been taken a step further, exploiting the mineralogical characteristics of particles to link comminution, concentration and smelting. This approach is demonstrated using a laboratory-based case study of a Ni-Cu sulphide ore. The case study focused on the effect of shifting energy between the comminution and smelting stages on the overall energy consumption for the metal production process. To model this effect the mineral composition of the particles was linked to the behaviour of the ore particles in the primary grinding, regrinding and flotation stages. This application of process mineralogy provides a methodology to minimise energy use across mineral concentration and smelting processes, an important aspect of sustainable processing.     

振动磨机介质的运动规律及工作参数的算法

通过对MZS型振动磨机磨筒内介质运动规律的观察研究,建立了一个简单的介质运动学模型,并根据所建立的模型计算了振动磨机的一些重要参数,如振幅、介质填充率、介质直径等工作参数的最佳取值范围,从而使振动磨机获得最佳粉磨效果和降低能耗。     

The effects of electrical comminution on the mineral liberation and surface chemistry of a porphyry copper ore

The surface chemistry and mineral liberation changes of a porphyry copper ore after high voltage pulse (HVP) electrical comminution have been investigated using X-ray photoelectron spectroscopy (XPS) and mineral liberation analysis (MLA). Previous studies suggest that electrical comminution has the potential to improve downstream flotation recoveries, due to increased mineral liberation. However, until now the effects on the surface chemistry have not been investigated in detail.The mineral liberation results showed that chalcopyrite was more liberated in the electrical comminution product than in mechanical comminution, noticeably in the coarser size fractions. The surface chemistry of pure chalcopyrite was investigated, using XPS, and high resolution scans of iron and sulphur showed that both comminution methods led to iron oxidising preferentially leaving behind a passivating film of copper sulphides. However, the HVP product oxidisation was more severe with more iron oxide being produced and further oxidation of the remaining copper sulphides into copper sulphate. An attrition grinding stage may be useful in removing the oxidised layer from the surface of the particles prior to flotation separation. This paper presents a new application of the HVP technology in hybrid procedures using electrical comminution and mechanical grinding to prepare the flotation feed, rather than using excessive pulse energy to fully disintegrate ore to the flotation size. Better liberation and flotation performance were achieved through the hybrid procedures than the comparative mechanical comminution.