CN115077463A (B)-Scientific characterization method for real surface roughness of ore grinding product

2022-09-20, UNIV NORTHEASTERN

Inventors: LI LIXIA; ZHANG CHEN; LIU MEIHAN; MENG QINGYOU; LU JIWEI; LIU FEIFEI; ZHANG YULEI; PAN ZHENYU

Abstract

The invention provides a scientific characterization method for the real surface roughness of ore grinding products. The scientific characterization method comprises the following steps: classifying the ore grinding products according to different narrow particle fractions; fully and uniformly mixing and dispersing the ore grinding product of each size fraction to prepare an AFM detection sample of each size fraction; through a peak force tapping mode of an atomic force microscope, performing three-dimensional imaging on the surfaces of the uniformly mixed particles of the ore grinding product to obtain a scanning image; analyzing the scanned image; after particle surface steps and crystal face boundaries in the scanned image are removed, the surface of a particle product is divided into a plurality of areas serving as RMS calculation areas, and RMS calculation is carried out; the root mean square of the heights of all the pixel points in the RMS calculation area is calculated to serve as the RMS roughness of the surface of the ore grinding product, and the longitudinal diameter depth of the roughness of the fracture surface is quantitatively represented; correcting errors existing in the AFM imaging process to obtain accurate data of h (x) and h (X, Y); calculating the roughness PSD of the surface of the sample on a three-dimensional plane, and quantitatively representing the spatial distribution density of the roughness.

Background technique

For metal ores, the purpose of grinding is to prepare materials with suitable particle size for subsequent sorting operations on the one hand, and to dissociate minerals on the other hand. During the grinding process, the particles are affected by impact, shear, friction, etc., and a series of surface properties change. The type of mill, the shape and size of the grinding medium, the grinding concentration and other operating parameters, as well as the mechanical properties of the ore itself, can cause mineral Differences in particle morphology, roughness, exposure of crystal faces, and reactivity. Flotation is a process of mineral separation based on the affinity/hydrophobicity of mineral components. Some researchers believe that different grinding products have different surface roughness (Ugur Ulusoy, Meftuni Yekeler, Correlation of the surface roughness of some industrial minerals with their wettability parameters, Chemical Engineering and Processing: Process Intensification, Volume44, Issue5, 2005, Pages 555-563, ISSN0255-2701, https://doi.org/10.1016/j.cep.2004.08.001.), reducing the particle surface roughness will increase its Surface hydrophobicity; other studies have shown that for hydrophilic minerals, increased roughness can enhance surface hydrophilicity, while for hydrophobic minerals, increased roughness results in increased hydrophobicity. By adjusting the roughness of the mineral surface, the separation of different minerals can be promoted. Therefore, scientifically characterize the surface roughness of grinding products, reveal the difference in surface roughness of different grinding products and the influence law on the hydrophobicity of mineral exposed crystal planes, coordinate the grinding and flotation process, and realize the impact of grinding on flotation behavior. Fine regulation is of great significance.

Roughness, which is the boundary formed due to atomic breakage, is the most prominent property of the particle surface and has a direct impact on wettability. At present, for the characterization of the surface roughness of grinding product particles (Rahimi M, Dehghani F, et al. 4):284-289.), the gas adsorption method to measure the specific surface area of particles can indirectly characterize the roughness, but it is affected by particle agglomeration and stacking. The direct characterization method for particle surface roughness is to manually manufacture different roughness of mineral surface with sandpaper of different modulus (Wang X, Zhang Q. Insight into the Influence of Surface Roughness on the Wettability of Apatite and Dolomite[J], Minerals, 2020, 10(2): 114.), observe the surface morphology by scanning electron microscope, measure the surface undulations of the particles with a roughness meter and perform weighted calculations to obtain the root mean square roughness (RMS) of the particle surface. There are 4 deficiencies in this method: (1) The surface roughness of the particles polished by sandpaper is not the roughness of the actual grinding product. The grinding process is a random and disordered process including impact, shearing and grinding. Sandpaper grinding is a regular grinding process, which cannot reflect the real roughness information of the grinding product; (2) This method does not take into account the particle size effect of the particle grinding behavior, the mechanical properties of each particle size, and the defects contained in it. Concentrations are different, resulting in different grinding behaviors of different particle sizes, and the surface roughness of each particle size grinding product is different; (3) SEM is a two-dimensional characterization method, which cannot reflect the three-dimensional information of roughness. It may be a three-dimensional long strip; (4) This method does not consider the density of roughness, and RMS has a good indication of the ups and downs of the sample in the vertical direction. For example, in Figure 1, the two sample surfaces have the same undulation height in the z-axis direction, and the two surfaces have the same roughness calculated by RMS, but the undulation density in the x-axis direction is obviously different.