Weathered Rock Crushing
The core objective of moisture content control technology in the crushing process of weathered rocks is to optimize crushing efficiency, control particle size distribution, reduce dust pollution, and ensure operational safety.
I. Core Control Objectives
1. Optimizing Crushing Efficiency: Within a certain range (usually with an optimal value), moisture can soften rocks, reduce their strength, and decrease energy consumption. However, excessive moisture can lead to adhesion and clogging.
2. Dust Control: Moisture is the most economical and effective means of suppressing dust. By increasing particle weight and cohesion, it prevents dust from becoming airborne.
3. Adjusting Product Particle Size and Shape: Moisture affects the brittleness of the rock and the operating conditions of the crusher, indirectly influencing the shape and gradation of the resulting aggregate.
4. Ensuring Safety and Stability: Preventing adhesion and clogging of high-moisture materials in the crushing chamber, chutes, and conveyor belts, and the resulting safety hazards such as equipment overload and blockage.
II. Main Control Technologies
1. Source Control and Pre-treatment
• Mining Planning: Plan mining areas based on weather and seasons. Prioritize mining areas with moderate moisture content, leaving overly wet or dry areas for later processing.
• Natural Drying/Air Drying: For weathered rock materials with excessively high moisture content, spread them out in the raw material yard for drying before entering the crushing system, utilizing solar energy and wind to reduce surface moisture.
• Rain Protection and Drainage:
◦ Covering: Cover the mined raw materials and finished product piles with waterproof tarpaulins.
◦ Drainage System: Set up a complete drainage system with drainage ditches and intercepting ditches in the mining area and storage yard to prevent rainwater accumulation and infiltration.
2. Process Humidification/Spray Dust Suppression Technology
This is the most commonly used and direct technology, the key being "precise spraying".
• Spray Point Selection:
◦ Feed Inlet: Pre-humidify at the transfer points of the conveyor belts feeding the crusher and screening machine.
◦ Crushing Chamber: Set up spray points above or inside the chambers of jaw crushers, cone crushers, etc.
◦ Screening Surface: Spray at the feed end and above the screen of the vibrating screen to improve screening efficiency and suppress screening dust. ◦ Transfer Points: Spray systems are installed at all transfer and discharge points of the belt conveyors.
• Spray System Types:
◦ Water Mist Nozzles: Produce a fine water mist with wide coverage, suitable for dust suppression, and have a limited effect on increasing the overall moisture content of the material.
◦ Spray Pipes: Produce small water streams, used for significantly humidifying the material.
◦ Automatic Control Spray System: Based on real-time monitoring (such as dust concentration sensors, material flow meters), it implements "spray on demand," saving water and preventing over-wetting.
• Additives: Chemical reagents such as wetting agents and binders are added to the water to reduce the surface tension of the water and improve the capture and agglomeration of fine dust, suitable for materials with strong hydrophobicity or extremely fine dust.
3. Process Dewatering and Drying Technology (for excessively wet materials)
• Mechanical Dewatering: After primary crushing, a dewatering screen (such as a high-frequency linear screen) is installed to remove excess free water and mud from the material.
• Thermal Drying: For high-quality aggregate production lines (such as those used for asphalt concrete), a rotary drying drum may be introduced after crushing and screening to precisely control the final product's moisture content. However, this is energy-intensive and mainly used for high-value-added products.
4. Process and Equipment Adaptability Adjustment
• Equipment Selection: For materials with expected high moisture content, select crushers with smooth bottom discharge and that are less prone to clogging (such as certain models of impact crushers and hammer crushers), avoiding the use of cone crushers with fine crushing chambers that are prone to clogging.
• Parameter Adjustment: Dynamically adjust the main shaft speed, discharge opening size, and feeding speed of the crusher according to the material humidity to optimize operating conditions.
• Process Design: Adopt a closed-loop circulation process, returning the coarse material with high moisture content from the screen back for further crushing, which helps to balance the system moisture. Design sufficient chute angles and anti-sticking liners to prevent wet material from adhering.
III. Monitoring and Intelligent Control System
The key to modern technology lies in achieving closed-loop control.
1. Monitoring Points:
◦ Raw Material Stockyard: Portable or fixed moisture meters. ◦ Key Process: Install online moisture meters (commonly using near-infrared or microwave principles) on the primary feed conveyor belt and the finished product conveyor belt.
2. Control System:
◦ PLC/DCS Integration: Integrate moisture monitoring data, equipment operating parameters, and spray system valves into a central control system.
◦ Intelligent Decision-Making: The system automatically adjusts based on real-time moisture data:
▪ Water pressure and flow rate of each spray system.
▪ Feeder speed (if moisture is too high, the speed is reduced to extend crushing time or match the drying process).
▪ Even issue warnings to prompt operators to intervene at the source.
IV. Key Technical Application Points and Challenges
• Optimal Moisture Content Range: This varies depending on the rock mineral composition (such as clay content), degree of weathering, and crushing process, and usually needs to be determined through testing. General experience suggests that controlling the material moisture content between 3% and 8% (for most aggregate production) provides a good balance between dust suppression and efficiency.
• Uniformity: The core challenge of the control technology is ensuring uniform distribution of moisture in the material, avoiding localized areas that are too wet or too dry.
• Winter Anti-freezing: In cold regions, the water addition process should be used cautiously, or antifreeze should be used to prevent freezing inside the equipment and in the material piles.
• Cost Balance: A comprehensive balance needs to be struck between water costs, electricity costs (pumping, drying), chemical reagent costs, and equipment maintenance costs versus the economic benefits of reduced environmental penalties due to dust, reduced material loss, and improved production efficiency.
Moisture control in weathered rock crushing has evolved from simple "water spraying for dust suppression" to a comprehensive precision control technology involving geotechnical mechanics, mechanical engineering, automation control, and environmental engineering. The development trend is: based on real-time monitoring data, dynamically adjusting humidification, dehydration, and process parameters through intelligent algorithms to achieve optimal closed-loop control of moisture content, thereby achieving the optimal production goals of safety, efficiency, environmental protection, and economy.
About of Baichy Heavy Industry
Baichy Heavy Industry is a high-tech mining equipment company integrating R&D, manufacturing, sales, and after-sales service. Focusing on crushing, grinding, and mineral processing equipment, we provide professional solutions to our customers. We are ISO9001:2015 、certified, and our products include mobile crushing palnts, crawler crushing plant, construction waste crushing plants, jaw crushers, sand making machines, cone crushers, fine crushers, grinding mills, ball mills, etc., all with reliable performance to meet diverse project needs.
Our advantages:
• Professional pre-sales support: Free project design and comprehensive solutions to help you accurately select the right equipment;
• Comprehensive on-site service: Providing installation guidance and worker training to ensure smooth equipment commissioning;
• Reliable after-sales guarantee: A complete after-sales system, timely response to technical inquiries and equipment maintenance, ensuring long-term stable operation.
To protect your rights, please contact us through the following official channels for professional service:
Official Website Customer Service
WhatsApp: 0086-15093222637
Email: [email protected]
We are committed to providing high-quality equipment and full-cycle services to deliver comprehensive intelligent solutions for the global mining industry!
