不同形状矿石单颗粒压缩破碎特性

Compression crushing characteristics of single ore particle with different shapes

为了从宏观-细观角度探究不同形状矿石颗粒的破碎强度、破碎模式、碎块尺寸分布及断口表面形貌等破碎特性,首先,基于三维扫描技术重构矿石颗粒图像,获取颗粒形状参数;其次,定量表征矿石颗粒外部宏观层次轮廓形态及细观层次凹凸度;最后,对扫描后的几何平均粒径范围为20~45 mm的不规则磁铁矿矿石颗粒进行单颗粒压缩破碎试验,并重构颗粒断口表面以定量探究断面粗糙度的影响因素。研究结果表明:矿石颗粒的破碎强度分布可用Weibull函数模型拟合,其中Weibull参数m为2.17,特征强度F0为7.20 k N;矿石颗粒破碎模式分为边部磨损、中部破碎、贯通缝破坏、随机开裂4种类型;中部破碎为主要破碎模式,占比为0.433,“第一尺寸碎块”及“第二尺寸碎块”质量分数分布均符合正态分布,均值分别在0.65和0.30左右;但当颗粒3个主维度长度接近时,颗粒不容易发生中部破碎。以分形维数D定量表征颗粒破碎断口表面粗糙度,当截面面积大于36 mm^(2)时,分形维数D更稳定。球度显著影响颗粒破碎断口表面平均分形维数D,扁平度、能量、棱角度及等效粒径4种因素影响程度次之且相近,延伸率的影响不存在统计学差异。

The study is to explore the crushing characteristics,such as crushing strength,crushing mode,fragment size distribution and fracture surface morphology of ore particles with different shapes from the macro-micro perspective.Firstly,the image information of ore particles was reconstructed to obtain the particle shape parameters based on three-dimensional scanning technology.Secondly,the external macro-level contour morphology and meso-level irregularity of ore particles were quantitatively characterized.Finally,the single particle compression crushing tests ware carried out on the irregular scanned magnetite ore particles with a geometric mean particle size range of 20−45 mm.The fracture surfaces of the particles were reconstructed to quantitatively explore the influencing factors of the roughness of fracture surface.The results show that the crushing strength distribution of ore particles can be fitted by Weibull function model,in which the Weibull parameter m is 2.17 and the characteristic strength F0 is 7.20 kN.The crushing modes of ore particles are divided into four types,including edge wear,middle crushing,through joint failure and random cracking.The middle crushing mode with a proportion of 0.433 is the main crushing mode.The mass fraction distribution of the"First size fragment"and"Second size fragment"about the middle crushing particles conforms to the normal distribution,and the mean values of them are about 0.65 and 0.30,respectively.However,when the three main dimensions of the particles are close to each other,the particles are not prone to middle crushing.The fractal dimension D is used to quantitatively characterize roughness of fracture surface of particle.When the section area is greater than 36 mm^(2),the fractal dimension D is more stable.The average fractal dimension D of particle fracture surface is significantly affected by sphericity,followed by the similar flatness,energy,edge angle and equivalent particle size,and there is no statistical difference in elongation.