Brown coal mill - brown coal crushing production process

Brown coal, also known as lignite, is a low-grade coal formed from the remains of land plants that lived and died about 15 to 50 million years ago. It is the earliest stage in the coalification process and contains a high amount of moisture, which makes it difficult to transport and use directly. Therefore, brown coal often needs to be processed to increase its energy density and reduce its moisture content before it can be effectively utilized.

The brown coal crushing production process typically involves the following steps:

1. Feedstock Preparation: The raw brown coal is typically mined and then transported to a processing plant. Here, it is sized to ensure it is within the appropriate range for the crushers. Over-sized pieces are often sent to a primary crusher for initial reduction.

2. Moisture Reduction: Before crushing, the brown coal may undergo a moisture reduction process. This can be done through threshing, where the coal is beaten or shaken to remove the outer layers and some of the moisture. It can also be dried using rotary dryers, flash dryers, or drum dryers to reduce the moisture content to a more manageable level.

3. Crushing: The moisture-reduced brown coal is then crushed to a fine powder using various types of crushers. The most common types of crushers used for brown coal include:

- Roll crushers: These crush the coal by passing it between two rollers that rotate in the same direction. The coal is squeezed and crushed as it moves through the gap between the rollers.

- Jaw crushers: These crush the coal by compressing it between a moving jaw and a stationary jaw. The coal is crushed as it moves down the cavity between the two jaws.

- Impact crushers: These crush the coal by impact, using a rotating hammer or plate to strike the coal and break it into smaller pieces.

- Hammer mills: These crush the coal by impact, using rotating hammers to strike the coal and break it into smaller pieces.

4. Size Classification: The crushed coal is then passed through a screening or classification system to separate it into different sizes. This ensures that the coal meets the specific requirements of the subsequent processing steps or end-use applications.

5. Pulverization: For applications such as power generation, the coal may need to be further pulverized into a fine powder. This is typically done in pulverizers, which are specialized mills that reduce the coal to a particle size that is suitable for burning in a boiler. The pulverized coal is then blown into the boiler with a stream of hot air or gas.

6. Collection and Storage: The crushed and/or pulverized brown coal is collected and stored in silos or bins until it is transported to the point of use. Dust collectors are used throughout the process to control airborne dust and ensure the safety of the operators and the environment.

7. Utilization: The crushed and processed brown coal is used in various applications, with power generation being the most common. It can also be used in industrial boilers, cement production, and as a solid fuel in other processes.

The brown coal crushing production process is designed to maximize the economic value of the coal by improving its handling properties and energy efficiency. The selection of the appropriate crushers and mills will depend on the specific characteristics of the brown coal, the required particle size, and the intended use of the coal. Proper maintenance and operation of the crushers and mills are crucial to ensuring the quality of the processed coal and the efficiency of the overall production process.