Criteria for selecting coal mills

Are you referring to the selection of coal grinding mills or their size? If it is a matter of selecting the size, then factors such as the coal feeding rate, Haas grindability index, discharge particle size, and amount of product obtained are important criteria for choosing the size of the coal grinder. When it comes to selecting the appropriate type of grinder, it depends on where it will be used; ball mills are used for boiler coal grinding, while wet overflow rod mills are more commonly used for coal slurry gasification, although ball mills are also employed (in the initial stage of coal slurry gasification)

Could the moderator explain the differences in the products produced by ball mills and rod mills? I’ve seen that ball mills are only used in many mines; the wet overflow rod mill is what we use for preparing water-coal slurry

It would be better if there were samples to check.

Steel balls for ball mills, steel rods for rod mills; ball mill steel balls, grinding steel balls, hot-rolled steel balls, hot-rolled ball mill steel balls, forged steel balls, machined steel balls, forged grinding balls, wear-resistant steel rods, wear-resistant steel balls, cast balls, high-chromium balls, ball mill forged steel balls. Contact person: Zhang Xun; Phone: 13953147415; QQ: 549551716. Shandong Huamin Steel Ball Co., Ltd. is located in Zhangqiu City, Shandong Province. Established in 1986, it has a registered capital of 20 million yuan. The company produces steel balls for ball mills and steel rods for rod mills. It is recognized as a high-tech enterprise in Shandong Province, a company that abides by contracts and values integrity, as well as a provincial enterprise technology center. Its products are designated as famous brand products in Shandong Province and its trademarks are also well-known in the region. The company has obtained ISO9001 quality management system and ISO14001 environmental management system certifications. After 24 years of development, Huamin Company has become a manufacturing enterprise with advanced production techniques, sophisticated equipment, and stable product quality. It has helped drive the growth of over 80 local enterprises, giving rise to an industrial base led by Huamin Company, where specialized and large-scale production takes place. The company made significant contributions to Zhangqiu City being designated as the “Home of Foundry in China” in 2010, and attended the award ceremony in Beijing. In May 2010, Huamin Company, as a key enterprise recommended by Zhangqiu City, participated in the \"China International Foundry Exhibition\". The company is engaged in charitable activities; it donated 500,000 yuan in 2009 and continued to make donations for three years in a row, which led to it being designated as a \"Charity Workstation\" by the Zhangqiu Charity Federation. Chairman Hou Yumin was honored as \"Changqiu City’s Most Compassionate Charity Donor,\" \"Jinan City May 1st Labor Medal Recipient,\" and \"Outstanding Entrepreneur of Jinan City.\" He has helped a total of 15 people in need or with disabilities over the years. Huamin Company attaches great importance to environmental protection. It was the first foundry in Zhangqiu City to switch from using coal-fired stoves to natural gas ones. In 2004 and 2005, it invested 3 million yuan to complete this conversion, thereby addressing the problems of energy waste and environmental pollution in the forging industry. This approach helped to save energy, reduce pollution, improve the working conditions for employees, and lessen their workload, achieving clean production and energy conservation. It was recognized as an advanced unit in environmental protection in 2004 and 2005. The company places great emphasis on technological innovation, and has been dedicated to the research and development of new types of wear-resistant materials, forged steel ball products, as well as European-style ironwork. It is equipped with advanced casting and forging production facilities, along with thorough product testing and inspection methods, and boasts a highly skilled professional workforce. Keeping pace with the international market and adapting to its demands, the company actively introduces and incorporates new technologies, upgrades its equipment, and develops new projects. It has developed China’s only automated production line for spin-forged steel balls; this line uses electric furnaces instead of the traditional air-hammer forging method. It is equipped with high-quality steel materials specifically developed for bainite and RCAB steel balls, as well as state-of-the-art heat treatment systems. Through precise control of the equipment, it is possible to produce high-quality ball mill balls of various hardness levels and mechanical properties, along with other types of grinding media, to meet customers’ requirements. Compared to traditional forging processes, the main advantage of precision rolling of steel balls is the continuous crystal flow. The precision-specification steel balls produced by Huamin Steel Balls are rolled from specially selected carbon steel and alloy steel. The manufacturing process of Huamin steel balls relies on advanced quenching equipment, which ensures uniform hardness on the surface of the steel balls as well as a consistent distribution of hardness. This results in a 20-fold increase in production efficiency, and it has earned a **patent grant**. Main products: 1. Steel balls for ball mills: (1) Hot-rolled forged steel balls: 100,000 tons per year, suitable for wet ball mills. (2) Cast balls (high, medium, low chromium): 20,000 tons/year, suitable for dry ball mills. 2. Steel rods for rod mills, 30,000 tons per year, suitable for various types of rod mills. Its wear resistance is twice that of ordinary hot-rolled round steel. Customers at home and abroad are welcome to call or write for inquiries. We will surely make every effort to provide our customers with products of consistent quality, the most competitive prices, timely delivery, and satisfactory service. Shandong Huamin Steel Ball Co., Ltd. Address: Zhangqiu City, Jinan, Shandong Province. Contact person: Zhang Xun. Mobile phone: 13953147415. QQ: 549551716

Reply to 3# haoshifeng1989: You don’t seem to know much about coal slurry gasification units. The earliest such units all used ball mills, while wet overflow rod mills were gradually adopted after 2004.

Huamin Company produces 30,000 tons of steel rods for rod mills each year; it is the largest manufacturer of such steel rods in China, and its products are sold to more than 20 countries and regions around the world. Huamin steel rods are suitable for a wide range of users of rod mills and coal grinding mills, including quartz sand plants, mines, cement plants, power plants, silica sand plants, sand aeration facilities, coal chemical industries, concrete plants, and manufacturers of new building materials. Huamin wear-resistant steel rods differ from ordinary rolled round bars; they are specialized new types of wear-resistant steel rods designed for use in rod mills and grinders, having undergone special heat treatment. Their wear resistance is 4-6 times that of ordinary steel rods, resulting in significant economic benefits. The steel rods currently in use in the market are produced by steel mills through rolling processes; they require low technical standards, have very poor wear resistance, and result in high consumption during use, leading to significant waste of ** resources. The main problems are as follows: 1. High wear: Due to low hardness and poor toughness, the consumption of round steel is very high, which in turn increases the workload and costs in the magnetic separation process, and even affects product quality. 2. Sharp ends at both ends: The sharpness of the steel rod’s ends is caused by various factors. The main reason is that the ends of the steel rod in a rod mill come into contact with the material for longer periods and over a larger area compared to the middle part, resulting in a longer effective grinding time at those ends. Once there is a noticeable difference between the condition of the ends and the middle part that can be seen with the naked eye, such a steel rod is considered “failed,” as it can no longer perform effective grinding functions inside the mill. 3. Broken rod: The reason is porosity within the material. Regarding the issues with steel billets in steel mills, only very large-scale mills are able to meet the stringent technical requirements involved, especially for those with a diameter of over 70 mm. While most steel mills can produce such billets, their compression ratio and hardenability are low, meaning that their structure is not dense enough. Furthermore, since the internal stress in the round bars is not relieved at the time of production, bar breakage occurs as if by explosion, starting from the inside. The process of producing steel bars in steel mills is similar to inflating a balloon; it is necessary to relieve the internal stress in order to prevent bar breakage. 4. Bent rod: The main reason for bent rods is that round steel has very low hardness and is relatively soft; therefore, it is prone to bending when subjected to external forces such as impacts in a grinder. Once one of the rods bends, it disrupts the parallel arrangement of the steel rods inside the mill (the rods run parallel to each other within the mill, and as material passes through the gaps between them, it is ground into small particles or powder). In mild cases, this disruption leads to reduced efficiency of the mill; in severe cases, the rods may be thrown out of the mill, posing a risk to the safety of the workers and causing damage to the mill as well as other production equipment. 5. Low production efficiency, and the qualified products do not meet the requirements. This problem plagues many companies for various reasons, and steel bars also have a significant impact on it. For example, issues such as an unreasonable ratio between steel rods of different diameters, improper loading amounts, inadequate replacement of steel rods, and failure to remove defective rods in a timely manner. Our company has invested heavily to hire various experts to study this product, with the aim of developing steel rods with higher wear resistance to replace the current consumable steel rods in use domestically. After years of research, production equipment for new types of alloy wear-resistant steel rods, as well as manufacturing processes for grinding rods made of different materials, have finally been developed. The wear resistance of this wear-resistant steel rod is 4 to 6 times that of a steel rod produced by rolling. Every year, it is possible to **save hundreds of thousands of tons, or even tens of millions of tons, of steel. Huamin’s wear-resistant rod production process: Communicate with the customer to understand their requirements for the steel rods, after which the material, model, and quantity are determined; large-scale steel mills supply the raw materials; the raw materials are inspected upon arrival at the factory; they undergo quenching and other heat treatment processes using the balancing method; further heat treatment steps are carried out; the products are inspected, stored, and then the customer is followed up with. The new type of wear-resistant steel rod produced using the equipment and processes developed by our company boasts a wear resistance 4 to 6 times that of round steel, addressing issues such as high wear, rod breakage, rod bending, and sharp ends at both ends. The size specifications can be adjusted to meet the customer’s requirements, enhancing flexibility and eliminating unnecessary waste. At the same time, it extends the service life, improves the production efficiency of the mill, reduces production costs, and lessens the workload on workers. This wear-resistant steel rod has the following features: (1) Its wear resistance is 1.5–2 times that of steel rods made by rolling, offering excellent wear resistance and helping customers save a significant amount of cost. (2) Produced using the latest methods, the dimensions can be adjusted to meet customer requirements, resulting in **increased flexibility and elimination of unnecessary waste. (3) It extends the service life, reduces costs, lessens the workload on workers, eliminates the need to worry about stopping the grinder daily to insert steel rods, and **also increases production. Introduction to key parameters: 1. Diameter: 18mm–110mm. 2. Length: 2.5m–7m. 3. Hardness: Can be adjusted according to customer requirements; for standard products, the hardness is between HRC45 and 55. 4. The raw materials are sourced from large domestic steel mills, and round bars with special chemical compositions can be manufactured as per customer requests. We welcome customers from home and abroad to visit our company for discussions. We are committed to providing high-quality products, timely delivery, competitive prices, and satisfactory service as the foundation for long-term cooperation. Zhang Xun, Shandong Huamin Steel Ball Co., Ltd. 13953147415 QQ: 549551716 Answers to common questions: 1. Analysis of broken or bent rods: (1) Causes: A. Material: internal porosity. Regarding the issues with steel billets in steel mills, only very large-scale mills are able to meet the stringent technical requirements involved, especially for those with a diameter of over 70 mm. While most steel mills can produce such billets, their compression ratio and hardenability are low, meaning that their structure is not dense enough. B. Process: The internal internal stress has not been relieved. Bar breakage is like an explosion – it starts from within. The principle behind steel mills’ production of steel bars is similar to inflating a balloon; it is necessary to eliminate the internal stresses in order to prevent bar breakage. (2) Solution: A. Focus on the materials. a. Try to use materials from **super-large steel mills** ； b. The new alloy material developed independently by our company (Huamin Grinding Rods) was specifically created by industry experts in wear resistance from Tsinghua University and Dalian University of Technology, taking into account the conditions under which rod mills operate. It possesses excellent hardenability, and is produced by a **very large steel factory (under a confidential agreement). B. Treatment Process: The steel rod treatment process developed independently by our company (Huamin Grinding Rods) has been granted a **patent**; it significantly improves the wear resistance of the steel rods and prevents breakage. C. Dimensions: The specifications can be adjusted flexibly. Generally, the steel bars supplied by steel mills are 6 meters long; if you use 4-meter long bars, then the 2 meters that remain will be wasted. Our company (Huamin Grinding Rods) can produce bars to custom lengths. 2. Hardness analysis of wear-resistant steel rods: The optimal hardness for these rods is between 45-50; values below this range result in the rods being too soft and not resistant to wear, while values above this range make them too hard and brittle, prone to breaking ； Furthermore, in terms of manufacturing processes, domestic manufacturers can only achieve an HRC hardness of over 45 on the surface of the steel rod for a maximum of one centimeter; once that 1 centimeter is ground, the surface becomes identical to that of a round steel bar. Our company (Huamin Wear-Resistant Steel Rods) produces wear-resistant steel rods for rod mills in accordance with international standards. Moreover, thanks to our proprietary manufacturing process (which has been granted a **patent**), the overall performance of these steel rods can be improved. For example, while ordinary steel rods have a surface hardness of HRC 45 and an internal hardness of HRC 10, our rods can achieve a surface hardness of HRC 50 and an internal hardness of HRC 25. 3. Differences between wear-resistant steel rods, steel rods, and round bars: Round bars are raw materials produced by steel mills; they are not finished products. Using them as steel rods for rod mills leads to various problems such as rod breakage and failure (with sharp ends at both ends). Their hardness is only 20, meaning they are completely not wear-resistant! Steel rods are produced by further processing of round steel; their surface hardness is 45-50, making the surface wear-resistant while the interior is not. In conclusion, wear-resistant steel rods are the true steel rods suitable for rod mills

Rod mills are used for rough grinding, while ball mills are used for fine grinding.