Vertical roller mill

Steel slag is harder and denser, often in block or granular form, with higher strength and larger specific gravity. Since steel slag solidifies by natural cooling or artificial control, it cools slowly and forms a larger crystalline structure, so its physical properties are closer to natural stone.

The chemical composition of steel slag is relatively complex, usually containing higher calcium oxide, magnesium oxide, silicon oxide and iron oxide. Due to the presence of these components, steel slag has a certain activity and can react with other substances under appropriate conditions. The main applications of steel slag include as an admixture in cement and concrete, road base material, and waste mine backfill material.

In addition, steel slag is often used in the production of building materials due to its hardness and wear resistance, and has a wide range of industrial uses. Water slag forms a glassy structure due to rapid cooling through water quenching, with a loose texture and smaller particles, usually in powder or granular form. Water slag has a smaller specific gravity and potential hydraulic hardness, which allows it to be further hydrated after mixing with cement, increasing the strength and durability of cement.

The chemical composition of slag is relatively stable, mainly composed of silicon dioxide, calcium oxide and aluminum oxide. This stable chemical composition makes slag a high-quality mineral admixture and is widely used in cement production. In addition, slag can also be used to produce building materials such as concrete and bricks, which can improve the performance of these materials and make them widely used in the construction field.

Slag mills are capable of handling materials with high hardness and strong abrasiveness. Slag mills are usually designed with more wear-resistant materials and more robust structures. For example, the materials of the rollers and discs are usually wear-resistant alloys, and even carbide inlays are used.

The rollers and discs must also be designed with strong wear resistance and impact resistance to meet the needs of slag handling. Due to its larger particles and higher hardness, slag has relatively low grinding efficiency and high energy consumption. Slag mills usually require higher roller pressure and greater power consumption to complete the grinding process.

Water slag mills are relatively lightweight in design because slag has a lower hardness. Rollers and discs are usually made of more standard wear-resistant materials, and the design focuses more on improving grinding efficiency and reducing energy consumption. The structure of the water slag mill can be relatively simplified to accommodate lighter materials.

Water slag has a higher grinding efficiency and relatively low energy consumption. Since slag is soft, the roller pressure and power required in the grinding process are lower, so that the slag vertical mill can achieve a better energy efficiency ratio in the production process.

The products of slag vertical mill usually have good fineness and uniformity. The particle size requirements of slag powder are high, which can meet the needs of cement production and other building materials. Therefore, the powder selector and grading system of slag vertical mill are usually designed more precisely to ensure the fineness and uniformity of the product.

Steel slag and other raw materials are transported into the factory by loading trucks, and then sent to the slag storage shed for storage and drying through the unloading hopper and belt conveyor. The stacked slag is picked up by a forklift, unloaded through a bar screen and entered into the receiving hopper, and the raw steel slag is evenly and quantitatively transported to the rubber belt conveyor through a metering belt conveyor.

During the transportation process, the raw steel slag is subjected to multiple iron removal operations by the iron removal device, and then quantitatively and continuously fed into the LM steel slag vertical mill for grinding through air-locking feeding equipment such as a screw conveyor.

The raw steel slag entering the mill falls into the center of the grinding disc. Under the action of centrifugal force, the steel slag moves evenly to the edge of the grinding disc, and is crushed by the continuous rolling of the grinding roller and the material layer. The ground steel slag powder is dried while being selected by the powder selector with the help of the hot air provided by the hot air furnace.

Steel slag particles with unqualified particle size fall back from the cone hopper to the grinding disc for re-grinding. The qualified slag powder is transported to the dust collector after being discharged from the mill along with the air flow, and then stored in the finished product warehouse by the air conveying chute and elevator.

Optimize the feeding particle size: Controlling the particle size of steel slag within the range of 20-30mm can significantly improve the grinding efficiency. According to industry research, after particle size optimization, grinding efficiency can be increased by 15%-20%.

Increase the grinding roller pressure: Steel slag has high hardness, so appropriately increasing the grinding roller pressure can increase the grinding force. By appropriately adjusting the grinding roller pressure (such as increasing from 6000kN to 7000kN), the grinding efficiency can be significantly improved. Relevant data shows that after increasing the grinding roller pressure, the grinding efficiency can be increased by 10%-15%.

Reasonable configuration of the powder selection system: Optimizing the speed and classification efficiency of the powder selector can effectively reduce the return powder rate and avoid repeated grinding of unqualified products. By adjusting the speed of the powder separator and improving the blade design, the powder selection efficiency can be increased by 5%-10%, thereby improving the overall grinding efficiency.

Hot air drying system is used: Steel slag contains a certain amount of moisture, which increases the difficulty of grinding. By introducing a hot air system, materials can be dried simultaneously during the grinding process, improving the working efficiency of the mill. When using a hot blast stove, drying and grinding are carried out simultaneously, the moisture content of the steel slag is controlled below 1%, and the grinding efficiency can be increased by 10%-12%.

High-hardness slag processing: The Mohs hardness of slag is usually between 5-7, especially in some converter steelmaking processes, the hardness of slag will be higher. To deal with high-hardness slag, slag vertical mills usually use wear-resistant alloy or carbide inlaid grinding rollers and grinding discs. According to experimental data, wear-resistant alloy materials can extend the service life of grinding rollers by 30%-50%, ensuring that the equipment maintains stable grinding capacity when processing high-hardness slag.

Medium-hardness slag processing: For medium-hardness slag (such as Mohs hardness between 4-6), slag vertical mills find a good balance between grinding efficiency and energy consumption. The grinding roller pressure is generally controlled at around 6000kN, and the grinding disc speed is between 60-80rpm. Through this configuration, the grinding efficiency and energy consumption ratio can be optimized to the best level. According to actual data, the grinding efficiency of this type of slag can usually reach more than 85%, and the energy consumption is low.

Low-hardness slag treatment: Some special slags (such as soft slag produced by blast furnace steelmaking) have a low hardness, with a Mohs hardness between 3 and 4. When treating this type of slag, the slag vertical mill can reduce the roller pressure to about 5000kN and adjust the grinding disc speed to 50-70rpm. For low-hardness slag, the grinding efficiency can reach more than 90%, and the energy consumption is 10%-15% lower than that of treating high-hardness slag.