Wyniki wyszukiwania - BazTech

1

The accurate algorithm of new surface area of single particle comminution, incorporating particle shape and roughness

Guo Qing, Zhou Qiang, Pan Yongtai, Zhu Changyong, Wei Yinghua

Physicochemical Problems of Mineral Processing

|

2021

|

Vol. 57, iss. 1

259--272

EN

Energy efficiency can be obtained by measuring accurate new surface energy in the crushing process. For the calculation of new surface energy, most researchers only pay attention to particle size distribution and ignore the influence of particle shape and roughness on the surface area. In this paper, the image processing technology was used to calculate the shape parameters and surface fractal dimension of the crushed granite sample. According to the different combinations of particle shape and roughness, the new surface area corresponding to the four basic models was calculated. For the surface area of a single particle, the calculation result of the rough model considering the surface fractal dimension is higher than that of the smooth model. Moreover, the ratio of the calculation results of the rough model and the smooth model increases significantly as the particle size increases. For 0.1 mm particles, the area ratio of the two models is 8, but for 25 mm particles, the area ratio reaches 130. In contrast, the particle shape is a secondary factor that affects the surface area calculation. The ellipsoidal model considering the particle shape has a surface area 30% larger than the spherical model. If the roughness and particle shape are considered when calculating the surface area, the energy efficiency of crushing is higher.

2

Modeling and optimization of activated carbon carbonization process based on support vector machine

Liu Gangyang, Zhang Chunlong, Dou Dongyang, Wei Yinghua

Physicochemical Problems of Mineral Processing

|

2021

|

Vol. 57, iss. 2

131--143

EN

Product prediction and process parameter optimization in the production process of activated carbon are very important for production. It can stabilize product quality and improve the economic efficiency of enterprises. In this paper, three process parameters of a carbonization furnace, namely feeding rate, rotation speed, and carbonization temperature, were adopted to build a quality optimization model for carbonized materials. First, an orthogonal test was designed to obtain the preliminary relationship between the process parameters and the quality indicators of a carbonized material and prepare data for modeling. Then, an improved SVR model was developed to establish the relationship between product quality indicators and process parameters. Finally, through the singlefactor experiments and the Monte Carlo method, the process parameters affecting the quality of a carbonized material were determined and optimized. This showed that a high-quality carbonized material could be obtained with a smaller feeding rate, larger rotation speed, and higher carbonization furnace temperature. The quality of activated carbon reached its maximum when the feeding rate was 1.0 t/h, the rotation speed was 90 r/h, and the temperature was 836°C. It can effectively improve the quality of carbonized materials.

3

Experimental research on the strength distribution of brittle spheres under compression

Zhou Qiang, Guo Qing, Pan Yongtai, Zhu Changyong, Wei Yinghua

Physicochemical Problems of Mineral Processing

|

2021

|

Vol. 57, iss. 2

58--69

EN

The strength of a particle is one of the most crucial characteristics within a comminution process due to the mechanical stresses experienced by each particle. In this study, the K9 glass spheres and ceramic spheres were subjected to a breakage test. The test includes the breakage of up to 240 particles under compression to obtain the distribution of the breakage probability depending on the crushing force and breakage energy. The breakage test was conducted for five particle size fractions from each individual material. Thus obtained 10 crushing force distributions and corresponding 10 breakage energy distributions were fitted with lognormal distribution function. The parameters in the lognormal were analyzed including the effect of the material and particle size. Following this, the relationship between the crushing force and breakage energy was analyzed based on the Hertzian elastic contacts model and Tomas’s elastic-plastic contact model, respectively. Additionally, particle strength in terms of crushing force and breakage energy were compared and found to be size dependent. Finally, a simple transformation algorithm of distributions is developed. According to this algorithm the crushing force distribution can be transformed into breakage energy distribution and vice versa. The findings facilitate a better understanding of the particle strength distribution under compression and will help to improve the comminution process design, control and optimization.

4

Experimental research on energy-size distribution model of coal particle bed comminution

Zhou Qiang, Guo Qing, Pan Yongtai, Zhu Changyong, Wei Yinghua

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 5

772--783

EN

In order to accurately predict the particle size distribution (PSD) of coal particle bed comminution under different applied pressures, the tests of two kinds of coal with four size fractions under five different applied pressures were carried out by TAW-3000 hydraulic servo testing machine. The Gaudin-Schumann(G-S) distribution is extended by the fractal theory and the JK size-dependent breakage model is discussed. Two mathematical models for predicting PSD of crushing products in coal particle bed comminution are proposed. Results show that the relationship between the mass-specific energy and applied pressure is linear. Because of the protective effect of fine particles, the change of particle size modulus d0 in G-S distribution is not significant, while the distribution parameter α decreases logarithmically with the increase of mass-specific energy. With the decrease of size fraction, the crushability of coal particle bed decreases, and a master curve can be used to fit the comminution characteristics of coal particle bed with different size fractions. The extended G-S distribution model and the JK size-dependent breakage model have better fit the results of coal particle bed comminution. This research provides a useful reference for the mathematical modelling of coal particle bed comminution.