微细粒钨矿的选矿工艺

以苯甲羟肟酸与辅助捕收剂WT为组合浮选药剂,采用浮选、YTF-C微细摇床精选和脱硫的工艺回收微细粒钨矿.工业试验结果表明,当浮选给矿品位(WO3)0.199%,-30 μm粒级(WO3)的质量分数达90%以上时,获得品位(WO3)47.30 %、回收率52.34%的钨精矿.该技术对回收微细粒钨矿有一定的借鉴作用.     

微细粒钨矿的选矿工艺

以苯甲羟肟酸与辅助捕收剂WT为组合浮选药剂，采用浮选、YTF-C微细摇床精选和脱硫的工艺回收微细粒钨矿,工业试验结果表明，当浮选给矿品位（WO3）0．199％，-30μm粒级（WO3）的质量分数达90％以上时．获得品位（WO3）47．30％、回收率52．34％的钨精矿．该技术对回收微细粒钨矿有一定的借鉴作用．     

A multiscale method for including fine particle effects in DEM models of grinding mills

A multiscale model for including interstitial powder or fine particles in DEM simulations of grinding mills is proposed. This consists of a traditional DEM model at the macroscale which includes only grinding media and potential coarser fractions of feed and product. Microscale models are embedded within this macroscale model. These can be sufficiently small that the fine powder can be included in a computationally affordable manner. The direct inclusion of the fine particles in the model allows predictions to be made of the effect of the local grinding environment on these fine particles. A shear cell is a good choice for the microscale model as it can well represent the local flow conditions at different points within the mill macroscale model. Averaging the macroscale flow allows the local collisional environments to be characterised and provides estimates of the shear rate and normal stress at each of the microscale locations which then controls the configuration of each microscale shear cell. A 1-way coupled implementation of this multiscale model is demonstrated for a simple cement ball mill. The relative importance of each region of the flow is determined with the toe region being the dominant contributor to the grinding. The grinding action produced by the shearing of thin layers of powder between adjacent layers of media flowing over each other is clearly demonstrated by the behaviour predicted in the microscale models. Methods for calculating power draw that include the effect of powder and for constructing collision energy spectra for the powder are described. Finally, the importance of the cushioning effect of high powder loads on the flow behaviour of the media is demonstrated.     

粒度对原煤破碎特性的影响

为解决循环流化床锅炉煤制备系统中原煤破碎能耗和破碎产物粒径较难预测的问题,在辊式破碎机和锤式破碎机上对淮北无烟煤进行了破碎实验,使用功率分析仪对破碎能耗进行了实时监测,并对产物进行了粒度分析。结果表明,用破碎产品的平均粒径和80%通过粒径作为细度模数可以很好的用邦德能耗公式描述破碎能耗规律,优化后的分形能耗公式适应性更广;辊式破碎机的破碎能耗随着给煤平均粒径的增大而线性增大;锤式破碎机存在一个临界粒径,在该粒径范围内,破碎能耗随着给煤粒径的增大而减小;对于辊式破碎机,给煤平均粒径相等时宽筛分颗粒的破碎能耗小于窄筛分的破碎能耗,且破碎产物中细颗粒的含量较高,锤式破碎机破碎时,这一差异不明显。     

The limits of fine particle flotation

Understanding the limits of fine particle flotation is the key to the selective separation of fine mineral particles. Fine particles have low collision efficiencies with gas bubbles and float slowly. There has been a great deal of work aimed at overcoming the inefficient collision of small particles with rising air bubbles. This review deals with the influence of bubble size, particle aggregation, different flow conditions, particle induction time, as well as the action of surface and capillary forces on fine particle–bubble capture. Recommendations for practice are given.     

Confined particle bed breakage of microwave treated and untreated ores

The effect of microwave treatment on the processing of mineral ores was investigated through simulations of microwave heating, thermal damage and confined particle bed breakage test on bonded-particle models. The simulations were undertaken on two-phase mineral ore consisting of a microwave-absorbing mineral in a non-absorbing matrix. The microwave heating was simulated by dissipating a volumetric heat source in the absorbent phase. The progeny size distribution and degree of liberation for the untreated and microwave treated ores after breakage tests were determined by undertaking image analysis of the model outputs. It was shown that microwave treatment at high power density considerably changed the progeny size distribution and enhanced the degree of liberation in confined particle bed breakage tests. It was also found that crushing velocity has a significant effect on both progeny size distribution and liberation, particularly for the ore treated at high power density.     

Experimental study on evolution law for particle breakage during coal and gas outburst

Coal and gas outburst is a dynamic phenomenon in underground mining engineering that is often accompanied by the throwing and breakage of large amounts of coal.To study the crushing effect and its evolution during outbursts,coal samples with different initial particle sizes were evaluated using a coal and gas outburst testing device.Three basic particle sizes,5–10 mesh,10–40 mesh,and 40–80 mesh,as well as some mixed particle size coal samples were used in tests.The coal particles were pre-compacted at a pressure of 4 MPa before the tests.The vertical ground stress(4 MPa)and the horizontal ground stress(2.4 MPa)were initially simulated by the hydraulic system and maintained throughout.During the tests,the samples were first placed in a vacuum for 3 h,and the coal was filled with gas(CH4)for an adsorption time of approximately 5 h.Finally,the gas valve was shut off and the coal and gas outburst was induced by quickly opening the outburst hole.The coal particles that were thrown out by the outburst test device were collected and screened based on the particle size.The results show the following.(1)Smaller particle sizes have a worse crushing effect than larger sizes.Furthermore,the well-graded coal particles are weakly broken during the outburst process.(2)As the number of repeated tests increases,the relative breakage index grows;however,the increment of growth decreases after each test,showing that further fragmentation becomes increasingly difficult.     

Understanding fine ore breakage in a laboratory scale ball mill using DEM

DEM models of fine grinding in ball and stirred mills have to date almost entirely focused on the motion of the media and their interaction with the mill configuration. For SAG mills, a large fraction of the feed material can now be accurately represented in DEM models. However, for other mill types with much finer feed materials, such as the second chamber of a cement ball mill, the vast numbers of feed particles makes their explicit inclusion in the models prohibitive. However, it is now feasible to model a periodic section of a laboratory scale ball mill and include the coarser end of the ore size distribution directly in the DEM model. This provides the opportunity to better understand the effect of media on the interstitial bed of powder and of the effect of the powder on the media. The effect of the powder fill level, which is varied between 0% and 150% of the pore space in the media charge, is explored. The distribution of the powder, its effect on power draw and the way in which it contributes to the pattern of energy utilisation is assessed. The simulation results are compared with experimental results from a test at similar ball loading and rotation rate and for several size fractions of ore at a range of powder fill fractions. Tracking the collision histories of specific ore particles within the charge allows estimates of the probability (per unit time) of collision between media and ore particles (the “Selection” function) and of the intensity of each collision which can be used to estimate the severity of breakage using the JKMRC breakage model (the “Breakage” function). The energy spectra indicate that for a typical ore, only very few collisions are large enough to cause damage to the body of each particle. This provides an estimate of the energy efficiency which is less than 10% at even the best operating conditions.     

A method of determination of permeability

A method is proposed for determining permeability of coals under conditions of steady-state deformation and stationary filtration mode by employing a reference core made of gas-non-sorbing material with a known permeability. The approach has been developed to assess the time of transition to the stable filtration. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 6, pp. 3–9, November–December, 2007.     

攀枝花微细粒级钛铁矿的回收

介绍了攀枝花0.019～0.074 mm微细粒级钛铁矿回收工艺的确定及钛铁矿浮选捕收剂的选择,阐述了前八和后八系列微细粒级钛铁矿生产流程的优化.经过工艺流程的优化和浮选药剂的调整,使微细粒级钛铁矿的总回收率达到了40%.     

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.     

攀枝花微细粒级钛铁矿的回收

介绍了攀枝花0．019～0．074mm微细粒级钛铁矿回收工艺的确定及钛铁矿浮选捕收剂的选择．阐述了前八和后八系列微细粒级钛铁矿生产流程的优化．经过工艺流程的优化和浮选药剂的调整。使微细粒级钛铁矿的总回收率达到了40％．     

The effect of particle breakage mechanisms during regrinding on the subsequent cleaner flotation

Stirred mills have been widely used for regrinding, and are acknowledged to be more energy efficient than tumbling mills. These two types of mills present different particle breakage mechanisms during grinding. In this study, the effect of regrinding by both mills on surface properties and subsequent mineral flotation was studied, using chalcocite as the mineral example. A rod mill and a stirred mill with the same stainless steel media were used to regrind rougher flotation concentrates. Different chalcocite flotation recovery was achieved in the cleaner stage after regrinding in tumbling and stirred mills. The factors contributing to the different recovery included particle size, the amount of created fresh surfaces, surface oxidation and the redistribution of collector carried from rougher flotation. All the factors were examined. It was determined that the predominating factor was the different distribution of collector resulting from different particle breakage mechanisms in the stirred and tumbling mills, in line with ToF-SIMS analysis. In the tumbling mill, the impact particle breakage mechanism predominates, causing the collector to remain on the surface of newly produced particles. In the stirred mill, the attrition breakage removes collector from the surface, and decreases particle floatability. Furthermore, the type of grinding media in the stirred mill also influences the subsequent flotation, again due to the change of particle breakage mechanisms. The results of this study demonstrate that the selection of regrinding mills and grinding media should not only depend on the required energy efficiency, but also on the properties of the surfaces produced for subsequent flotation.     

Reinforced terraced fields method for fine tailings disposal

New mining technologies can exploit low-grade ores but they produce high volumes of waste, such as tailings. Further, current mineral processing techniques produce more and more fine tailings. How to dispose of these tailings is a key issue in the sustainable operation of a mine. A traditional method is to construct a settling or tailings pond for storage. Such a method requires sufficient coarse particles to raise a dam or embankment. However, the fine tailings contain little coarse particles and have poor mechanical properties. The stability of a tailings dam thus becomes a major issue if the traditional method is used. According to statistical data, all fine tailings dams or ponds in China have failed or have failure potential. Therefore, fine tailings disposal is a challenge to mine operators and new disposal methods should be explored for the stability improvement of tailings dams. In this paper, an innovative method of reinforced terraced fields is presented to satisfy the specific requirement of fine tailings disposal. By using an actual mine, this paper reports in detail the design concept and procedures for this method. Its feasibility is evaluated and its fundamental are analyzed.     

细粒煤泥的沉降方法--载体沉降

收捕介质(载体)与要处理的煤泥水混合,加入凝聚剂和絮凝剂,通过改变颗粒表面性质或桥联作用使细颗粒粘附于收捕介质上或通过桥联作用形成粒度大、重量大的絮团,使其整体沉降速度提高,澄清水浓度降低,最终达到细粒煤泥全部被捕获沉降.     

The dependency of the critical contact angle for flotation on particle size - Modelling the limits of fine particle flotation

The flotation behaviour of fine particles is studied in this work. Fine methylated quartz particles within the size range from 0.2 to 50 μm, and with varying contact angles, were floated in a mechanical flotation cell. Results indicate that particles of a given size need to possess a minimum critical contact angle, which increases in value as particle size decreases, for flotation to be initiated. As a consequence, a non-floating component exists within a given size fraction. This is interpreted as a fraction consisting of particles below the critical contact angle for flotation for that size. The critical contact angle for flotation is explained in terms of the existence of an energy barrier for bubble-particle attachment. The flotation results are interpreted by means of [Scheludko et al., 1976] and [Drelich and Miller, 1992] models for the floatability of fine particles. The experimental data compared very well with calculations using the Drelich and Miller equation, allowing extension to the prediction of the critical contact angle for flotation down to particle sizes well below the previous limits investigated, bridging the gap existing in the literature.     

细粒煤重选设备的技术现状与分析

细粒煤的分选技术装备是洁净煤技术的重要发展方向,而重选是当前最经济环保的选矿方法。文章从旋流器分选、液固流化床分选、离心重选等四个方面对当前细粒煤重选技术装备的研究应用情况进行了综述,分析了不同设备的优缺点,指出引入离心力等复合力场的新型高效重选设备将是细粒煤分选技术的未来。     

DEM modelling of non-spherical particle breakage and flow in an industrial scale cone crusher

Predictions of particle flow and compression breakage of non-round rock passing through an industrial scale cone crusher are presented. The DEM (Discrete Element Method) particle breakage model is generalised to allow non-round particles to be broken into non-round progeny. Particles are broken in this DEM model when the elastic energy of a contact is sufficiently high to initiate fracture. Progeny size distribution data from JKMRC Drop Weight Test (JKDWT) or JKMRC rotary breakage test (JKRBT) is used to generate the specific daughter fragments from each breakage event. This DEM model is able to predict the production of both coarser progeny which are resolved in the DEM model and finer progeny which are not. This allows the prediction of product down to very small sizes, limited only by the fineness of the fragments measured in the breakage characterisation. The predicted flow of material through the crusher, product size distribution and liner wear are discussed. The generalised breakage model demonstrated here is suitable for modelling all forms of crushers.     

岩石节理粗糙度新指标及新的JRC确定方法

为使二维粗糙度指标能够反映岩石节理形貌的方向特征,同时可以克服采样间距取值对粗糙度指标大小的影响。将岩石节理面划分为一系列连续的长方体微凸体,提出一种确定长方体微凸体计算长度的计算模型。通过平均同一剪切方向上长方体微凸体的计算高度提出了一个新的描述形貌面粗糙度的指标c。指标c是由长方体微凸体2种破坏模式结合一种确定长方体计算长度的模型得到,可以将节理几何特征与剪切强度结合起来,进而将节理粗糙度与节理剪切强度结合起来,这就为考虑剪切方向性的岩石节理剪切强度公式的提出提供可能。粗糙度指标c可以将形貌面客观定量表示,同时具有方向性,即剪切方向不同时对应的c不同。以标准JRC曲线为例,基于图像分割技术提取了标准JRC曲线坐标信息,阐述了粗糙度指标c的计算过程。在某一测量间距下获取的粗糙度指标不足之处是比该测量间距较小的粗糙度将被掩盖,而小尺度的粗糙对于抵抗剪切的贡献不应被忽略。通过计算不同采样间距的粗糙度指标c,发现指标c随着采样间距增大而呈幂函数形式减小,显示具有分形特征。基于分形思想,提出可同时反映节理形貌面各向异性并且不受测量尺度影响的粗糙度评价系统。分析了粗糙度描述系统指标与JRC之间的关系,证明该描述系统指标可与节理剪切强度建立良好的关系。