# Development of an Electric Pulse Device for Coal Grinding
## 1 Introduction  
In recent years, electric pulse technologies have attracted the attention of researchers and engineers due to their ability to provide selective and energy-efficient fragmentation of solid materials. The development and implementation of such technologies are reflected in numerous scientific studies describing the designs of electric pulse installations for the preliminary grinding of solid materials. Electric pulse grinding (EPG) is also known as [1] electric pulse fragmentation (EPF), electrohydraulic fragmentation (EHF), electrohydraulic forming (EHF), or high-voltage pulse fragmentation (HVPF). This method is a high-rate sheet-metal-forming process that is based on the electrical discharge of high voltage capacitors in a water-filled chamber. The high pressure and shock waves generated in the process are transferred to the solid material, causing its disintegration [2]. The use of high-voltage electric pulses ensures effective crushing with relatively low energy consumption compared with traditional mechanical methods. The absence of chemical reagents and reduced dust generation make electric pulse technology a more environmentally friendly technology. Additionally, it allows for the efficient processing of any conductive metals and alloys, regardless of their physical properties [2; 3]. The electric pulse method of material destruction is particularly relevant in the coal industry, where high-quality grinding and minimal impurity content are required. One study [4] examined the potential for producing coal-water fuel and for extracting rare elements from coal deposits using electric pulse technology. The authors proposed using the electric pulse destruction process for the integrated use of raw coal and its crushing and grinding while producing minimum ash content, a narrow particle size distribution, and the complete extraction of minerals. This could contribute to a more efficient use of coal resources and meet the growing demand for various materials. This method is also in demand in various fields of application, including in surface cleaning [5; 6; 7; 8], material fragmentation and ore beneficiation [9; 10; 11; 12; 13; 14], the extraction of residual valuable minerals [15; 16; 17], and other technological processes [18; 19; 20]. Traditional mechanical grinding methods have several disadvantages. Studies such as [21; 22; 23; 24] describe various mechanical grinding technologies--impact, abrasion, fracture, and shearing--used in mining and processing industries. These traditional mechanical methods remain widely used in crushing and processing within the mining and processing industries due to their effectiveness and relatively low capital costs. However, they have specific energy costs of up to 20-25 kWh/t, whereas the electropulse method can reduce this figure to 8-12 kWh/t, depending on the material characteristics and processing mode [13; 14]. One study [25] described the development of high-voltage pulse generators for the electric-discharge grinding of materials, which were proposed as alternatives to traditional mechanical methods. The authors developed generators with fully automated control that provided output voltages up to 400 kV and stored energy exceeding 1 kJ. The study included the design and operating principles of electropulse installations, a detailed analysis of various pulse-generator circuits, including the use of Marx generators and linear pulse transformers, to create efficient material fragmentation installations. These installations allow the output voltage amplitude, electrical-discharge energy, and pulse repetition frequency to be varied over a wide range, making them suitable for crushing various materials. A study conducted by the Julius Kruttschnitt Mineral Research Centre (JKMRC) [26] confirms the effectiveness of electric-discharge technology (EDT) in mineral raw material grinding. Specifically, a comparative analysis of platinum ore grinding established that achieving effective mineral liberation using EDT requires specific energy above 90 kWh/t.