The production of lithium slag and steel slag composite powder achieves high-value utilization of solid waste through refined ingredients, efficient vertical mill grinding and strict magnetic separation to remove iron, balances activity and stability, and is suitable for high value-added fields such as building materials.

The production method of lithium slag and steel slag composite powder mainly involves the steps of raw material pretreatment, ingredient mixing, vertical mill grinding, magnetic separation and iron removal, and key process parameter control. The following are the detailed production process and technical points:

Production process and process steps

1. Preprocessing stage

○ Steel slag treatment: The steel slag is processed for metal recovery (such as magnetic separation to recover metallic iron) to obtain steel slag tailings, which are then sent to the main steel slag batching bin.

○ Lithium slag treatment: The lithium slag (which may include lithium slag A, lithium slag B, lithium slag C, etc. from different sources) is sent to the lithium slag auxiliary material bin to ensure that the raw materials are dry and free of large impurities.

2. Prepare mixed slag

○ Mixing by weight: Steel slag tailings and lithium slag are accurately mixed in a ratio of 9~6:1~4 through a quantitative feeder, and then enter the screw conveyor after mixing.

○ Modifier addition (optional): Modifiers (such as chemical additives that enhance activity) may be added to optimize the performance of the composite powder in some processes.

3. Vertical mill grinding

○ Grinding equipment: Use vertical mill (such as tire vertical mill) for efficient grinding.

○ Key parameter control:

■ Grinding roller pressure: usually controlled at around 13MPa;

■ Grinding disc liner inclination angle: about 3.1°;

■ Grinding bite angle: 5~6°;

■ Hot air temperature: inlet temperature 300-360℃, outlet temperature 85-95℃;

■ Air volume: 20×10⁴~21×10⁴m³/h;

■ Powder selection machine speed: 115-135r/min.

○ Grinding goal: to obtain composite powder that meets the fineness requirements (usually 400~500 mesh) and separate unqualified return materials.

4. Magnetic separation and iron removal

○ The ground materials go through:

■ No. 3 self-unloading electromagnetic iron remover;

■ No. 1 dry powder permanent magnetic drum separator (double magnetic separation);

■ No. 2 dry powder permanent magnetic drum magnetic separator (third magnetic separation).

○ After magnetic separation, the slag iron and magnetic separation powder are stored separately, and the returned materials enter the vertical mill for grinding again.

5. Finished product storage and quality control

○ Qualified composite powder enters a dedicated storage warehouse to ensure activity indicators (such as the ability to form a CaO-SiO₂-Al₂O₃ gelling system) and stability (avoiding expansion problems by controlling the SO₃ content ≤3.0%).