Tunnel mud treatment equipment

Tunnel mud treatment equipment is specially used to treat the mud (also known as drill cuttings, mud waste) generated during tunnel construction. It aims to separate the solid and liquid phases in the mud, recover reusable drilling fluid, reduce waste emissions, and ensure compliance with environmental regulations. Tunnel construction mud mainly comes from underground projects such as shield method and TBM (tunnel boring machine) method. It is characterized by containing a large amount of rock powder, clay, water and possible chemical additives. The following are the main components, working principles and treatment processes of tunnel mud treatment equipment: Main components: 1. Vibrating screen: As the first-level separation equipment, it separates large-particle drill cuttings through screens of different mesh sizes while allowing the liquid phase of the mud to pass through. 2. Desander/Desilter: The centrifugal separation principle is used to further separate the mud after being treated by the vibrating screen. The desander is mainly used to separate sand particles with larger particle sizes, while the desilter is used for finer mud particles. 3. Centrifugal separator: For mud containing a large amount of fine particles and high viscosity, the centrifugal separator provides higher precision solid-liquid separation. In the high-speed rotating drum, the solid phase (drill cuttings) is separated from the liquid phase (drilling fluid) by centrifugal force. 4. Mixing tank/mixing system: used to mix new slurry, recycled slurry and add treatment agents to adjust the properties of the slurry, such as specific gravity, viscosity, filtration loss, etc., to meet the construction requirements. 5. Mud pump: responsible for the transportation of mud between treatment equipment to ensure the continuous operation of the entire treatment process. 6. Slurry storage tank: used to store qualified mud after treatment for recycling in the construction process. Working principle and treatment process: 1. Collection and preliminary separation: Collect mud from the tunnel excavation site and send it to the vibrating screen through a slurry pump. The vibrating screen separates large-particle drill cuttings from the liquid phase of the mud through high-frequency vibration. The large-particle drill cuttings are discharged from the screen surface, and the liquid phase mud passes through the screen holes to enter the next step of treatment. 2. Secondary separation: The liquid phase mud after preliminary separation is finely separated by a desander and a desilter. The mud forms a strong vortex inside the equipment. Due to the centrifugal force, solid particles of different sizes are deposited on the wall of the equipment and then discharged through the sand outlet. The liquid phase flows out through the overflow port and enters the next treatment link. 3. Deep separation and purification: For mud containing more fine particles or high viscosity, a centrifuge may be required. The drum inside the centrifuge rotates at high speed. The drill cuttings adhere to the inner wall of the drum under the strong centrifugal force to form a solid phase layer, and the liquid phase flows toward the center under the push of the spiral blades and is discharged through the liquid phase outlet. The mud after centrifugal separation has higher purity and can be directly reused in construction. 4. Mud performance adjustment: The qualified mud after treatment enters the mixing tank and is mixed with the newly prepared mud, treatment agent, etc. to adjust its performance indicators such as specific gravity and viscosity to meet the specific requirements of tunnel excavation. 5. Storage and recycling: The mud with adjusted performance is stored in the slurry storage tank and transported back to the tunnel excavation equipment by the mud pump for recycling. Additional treatment steps: - Flocculation and sedimentation: In some cases, it may be necessary to add flocculants after primary separation to aggregate fine particles and further separate them by gravity sedimentation or flotation. - Drying treatment: For the separated solid drilling cuttings, drying equipment is sometimes used for drying to reduce their volume for subsequent disposal or resource utilization. The selection and configuration of tunnel mud treatment equipment should be determined comprehensively based on the specific geological conditions, mud characteristics, environmental protection requirements and construction technology of the tunnel project to ensure the efficient and stable operation of the mud treatment system while minimizing the impact on the environment.