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Thermal Power Generation
Published in T.M. Aggarwal, Environmental Control in Thermal Power Plants, 2021
The ball mill is insensitive to foreign bodies in the feed material, and the wear of the grinding media can be compensated without any great effort or cost. The relatively long residence time of the coal in the mill has the effect of equalizing any short-term variations in the quality of the mill feed, thanks to the blending action of the system. Also, harder constituents such as quartz and pyrite are effectively pulverized.
Particle Management
Published in Debasish Sarkar, Ceramic Processing, 2019
The ball mill, a type of fine grinder, is one of the most used milling machines. It works on the principle of impact, i.e., the size of particles is reduced by the impact of milling media. A ball mill consists of a slightly inclined or horizontal hollow cylinder rotating about its axis, partially filled with material and grinding media. The grinding media is of a spherical shape or balls made up of steel, ceramic, stone or rubber depending upon the material being grinded. The inner surface of the cylinder is lined with an abrasion-resistant lining; frequently rubber lining is employed to reduce the wear. In order to produce finer particles, ball mills are more suitable as compared to other tumbling mills, as ball mills can produce finer particles ranging from 10 µm to a fraction of a micrometer [4].
Fuels commonly in use for clinker production
Published in Anjan Kumar Chatterjee, Cement Production Technology, 2018
Petcoke, being highly abrasive and hard, is difficult to grind. The grinding system, therefore, has to be designed to minimize the wear of mill components, the transport system, and ducting. Petcoke can be ground either in a ball mill or a vertical mill. While a ball mill system is simple and rugged, it cannot handle higher moisture contents and its specific energy consumption is high; the vertical roller mill system can handle higher moisture content in petcoke and is energy efficient but the expected wear of its components would be high. Depending on the hardness of petcoke and the fineness required for firing (4–6% residue on a 90-μm sieve), the expected capacity of the basic mill after conversion from coal firing may reduce by 50–80% of the basic output of the coal mill.
Fractal approach of particle size distribution description of ball milling products: effects of ore type, feed and particle size
Published in Canadian Metallurgical Quarterly, 2023
In the present study, all the constant mill parameters (including size distribution of the balls, the weight of the crusher load, milling time, and mill speed) and the mill's specifications Table 1 indicate that the capacity of the ball mill under such maximum conditions was equal to 1250 gr and, therefore, the mill was fed at three capacities of 750, 1000, and 1250 gr. As shown by the results, the obtained fractal dimension decreased with an increase in the feed. Accordingly, there is an inverse relationship between the fractal dimension and the feed. On the one hand, with an increase in the feed, the size distribution of the products usually decrease in the d80 mill, which is indicative of the reduced grinding of the material and reduced production of fine particles. On the other hand, the fractal dimension is directly related to the amount of fine-grained materials, meaning that as the amount of fine-grained particles is increased, the value of the fractal dimension will be increased accordingly. Accordingly, increasing the feed reduces the amount of fine-grained material, leading to a reduction in the fractal dimension. Moreover, when the feed is increased, the resulting products will exhibit a more uniform size distribution, which will lead to a reduction in the fractal dimension.
Investigation of parameters toward development of an empirical model for the pyrolysis of black oil-shale
Published in Petroleum Science and Technology, 2021
Emad A. M Abdelghani, Krishna Prasad Rajan, Abdelaziz A. Noaman, Ibrahim H. Ali
The experimental technique employed in this study is continuous weighting method to determine the loss of weight of oil-shale sample during the thermal treatment. The oil-shale samples collected from shale fields of Quseir-Safaga in the Eastern Desert of Egypt were crushed, homogenized and ball milled in the laboratory. Armfield solid handling bench (CEN-MKII-11) was used for ball mailing and size distribution analysis. The ball mill is a type of grinder that is used to reduce the size of solid materials using porcelain balls as the grinding medium. The mill consists of a PVC cylindrical drum that rotates in the horizontal plane. The composition of oil-shale of Quseir-Safaga in the Eastern Desert area of Egypt is elaborated elsewhere (A. M. El-Kammar et al. 1990; Moustafa et al. 2014). The experimental apparatus used in this study is pictorially represented in Figure 1. The upper part of the set-up has a thermo-balance under which the sample is suspended by means of heat resistant stainless steel wire ending with an exchangeable stainless steel basket of sample. The lower part is an insulated furnace. The insulation was provided by FIBREFRAX DURABLANKET S, which is manufactured from spun ceramic fibers. A vertical alumina tube is fixed in the center part of the furnace. The temperature of heating zone is measured by means of a Type K thermocouple (chromel/alumel) inserted into the furnace.
Experimental Study on Multibody Friction and Wear Properties of Liner in Ball Mills
Published in Tribology Transactions, 2021
Yuxing Peng, Zixin Yin, Zhencai Zhu, Xu Ni, Shengyong Zou, Guoan Chen
The ball mill is a device for grinding minerals or other granular solids. It contains a charge consisting of the grinding media and mineral to be ground, with water or without water. Size reduction of minerals is done by lifting the grinding media to impact the minerals until the required size is attained. As shown in Fig. 1, the regional distribution of the charge motion inside the mill shell is commonly divided into four regions; that is, the cataracting region, the cascading region, the grinding region, and the fracture region. The inner surface of the mill shell is fitted with a liner, which is used to protect the mill shell from wear and deliver the energy from the mill to the grinding media (1–5). In the ball mill, the liner is easily worn, and liner wear leads to reduced mill efficiency. It is widely known that the multibody friction and wear mechanism consists of two categories (grinding and impact) in ball mills. The grinding mechanism mainly occurs in the fracture region and grinding region where the liner is subjected to rolling friction and wear. The impact mechanism mainly occurs in the fracture region where the liner is subjected to impact wear and shear friction. However, the multibody friction and wear on the liner is difficult to measure, especially in the wet grinding condition. Little is known about the multibody friction and wear properties of liners in the grinding region and fracture region. Hence, it is of significance to investigate the impact and grinding behavior in ball mills.