Computer-Aided Design and Fabrication of a Dry Wind-Sifter Separator

Abstract

In this study, the simulation of a newly designed wind-sifter separator for dry beneficiation was deployed to upgrade −6.7 + 3.36, −3.36 + 1, and −1 mm coal. The wind-sifter principle is very effective for particle separation as it is based on the separation of lighter particles from heavier ones. First, the study entails computer simulations by utilizing the Lagrangian particle tracking method to observe the effectiveness of the wind sifting principle in separating particles based on their density in an air stream. From the three particle size fractions used, the simulation test results show that at a cut-point of 1.5 RD, yields of 29.1, 54.3, and 99.4% were attained at different optimum velocities for −6.7 + 3.36, −3.36 + 1, and −1 mm, respectively. The effect of operating parameters such as the mass flowrate and air velocity on yield, ash content, and calorific value were determined using the fabricated separator. A preliminary experimental study showed that the separator was effective in upgrading the feed coal with 30.28% ash content and 21 MJ/kg calorific value to clean coal with 18.94% ash content and 26.8 MJ/kg calorific value. A laboratory-scale wind-sifter separator was fabricated based on the results from the simulation test, which served as the first applied prototype in the field of dry coal beneficiation.

Wind-Sifting Separation: A Review

“…15−17 Figure 5 shows a typical zigzag sifter and gas cyclone assembly. The research conducted by Alade et al 2 for dry coal beneficiation entailed the use of the zigzag separator in tandem with a diffuser separation chamber (cocurrent separation). The function of the diffuser chamber is to ensure clean coal products are separated based on their relative densities (the cleaner the coal, the further the particles travel to their settling points).…”

“…19−20 The design works Figure 6. Designed zigzag separator for dry coal beneficiation by Alade et al 2 . 1, air blower; 2, air filter; 3, safety relief valve; 4, throttle damper; 5, 100 mm diameter flex; 6, air inlet into the first chamber; 7, rotary airlock valve for the coal-feed; 8, variable frequency drive motor drive for the rotary hopper valve; 9, first chamber (the wind-sifter) with the zigzag section; 10, support frame for the wind-sifter; 11, coal bin for the first chamber; 12, exit of the clean coal from the first chamber into the second chamber; 13, second chamber (diffuser chamber) to collect the clean coal; 14, coal bin for the second chamber; 15, filter section (with filter cartridge) to prevent coal dust from escaping to the environment; 16, air exit from the separator; 17, velocity measuring port; 18, support stand for the filter compartment.…”

“…However, in air or water, there is a resistance to this movement because of viscosity. Resistance increases with velocity, and when equilibrium is attained between the gravitational and fluid resistances forces, the particles come to rest as they attain what is known as the terminal/settling velocity. , Particle separation is possible when these solid particles reach their respective settling velocities due to different sizes and densities.…”

“…The wet classification entails the use of hydraulic fluids (liquids) like water for the separation of particles. While this classification is known to provide excellent separation efficiency, some drawbacks, including negative environmental impacts and high operational capital costs, have made dry classification a viable alternative. − The primary purpose of classification is to separate coarse particles in a particle mix from fine particles. With dry classification, the processing of particles in various sizes ranging from fine powder to pellets, flakes, and even two-dimensional materials such as paper and aluminum foil is achievable. , The separation of particles without using water as a sorting medium has been implemented for decades, with many new inventions and techniques now in the literature.…”

“…In the case of wind-sifting, this technique sometimes involves the use of sieves for the classification of particles and sometimes without sieves, as seen with the zigzag wind-sifter, which uses air primarily for particle sorting . The wind-sifting separation techniques have been used in various applications and in the diverse recycling of materials like electronic waste (e-wastes), municipal solid wastes, food, furniture, pharmaceuticals, minerals, chemicals, and metallurgical, and it has recently been applied in the field of coal processing. ,, …”