How to operate a concrete batching plant?
This may seem like a simple question, but it actually involves a systematic engineering process covering equipment, technology, safety, and cost.
Did you know? For the same HZS90 concrete batching plant, the daily output difference between an experienced operator and a novice can reach 20% to 30%. Moreover, waste material loss caused by measurement errors could amount to hundreds of dollars per month.
Next, we will discuss how to operate a concrete batching plant properly. This article avoids complex theoretical formulas and instead provides a practical, step-by-step operational guide based on real-world experience.
Preparation Before Startup
Do you know the pre-startup preparation procedures for a concrete batching plant?
Proper operation doesn’t begin with pressing the start button—it starts with pre-shift inspections. Experienced operators typically arrive 30 minutes early to complete the following checks:
1. Visual and Structural Inspection
- Check the mixer, aggregate silo, cement silo, and fly ash silo for any abnormal deformation or signs of material leakage.
- Inspect conveyor belts for tears or misalignment, and ensure idler rollers rotate freely.
- Verify the sealing condition of screw conveyor housings to prevent clogging from cement clumping.
2. Lubrication and Hydraulic System
- Confirm that oil levels at all lubrication points (such as mixer shaft ends, discharge gate hinges, and gear reducers) are normal.
- Check hydraulic station oil level and quality; replace hydraulic oil if it shows emulsification or excessive contamination.
3. Weighing and Metering System Zeroing
- Power on the instrumentation system and verify that all load cells display zero.
- Use standard weights to spot-check the metering accuracy of 1–2 hoppers; allowable error should be within ±2%.
4. Pneumatic and Electrical Systems
- After starting the air compressor, confirm that the air receiver pressure reaches 0.6–0.8 MPa.
- Test the operation of all pneumatic discharge gates to ensure smooth and accurate movement.
- Check the control cabinet for unusual odors or noises, and confirm all circuit breakers are in proper working condition.
Standard startup procedure
Do you know the correct startup procedure for a concrete batching plant?
The startup process must follow the principle of “from auxiliary to main, from rear to front,” and starting under load is strictly prohibited:
- Power on: First supply the main power, then sequentially close the circuit breakers in the control cabinet.
- Start the air compressor: Wait until the air tank pressure reaches the set value (typically above 0.6 MPa).
- Start the mixer: Run it unloaded, confirm that the mixing arm rotates in the correct direction with no abnormal noise, and let it idle for 1–2 minutes.
- Start the belt conveyor: Run it unloaded for 1 minute, ensuring there is no misalignment or slippage.
- Start the screw conveyor: Confirm that the motor current is normal to prevent clogging caused by cement clumping.
- Self-check the weighing system: Perform one complete cycle of “empty hopper zeroing—calibration—zeroing” for each silo.
- Trial operation: First produce 1–2 batches of low-grade concrete or mortar to verify smooth coordination among all systems before full-scale production.
It should be noted that some operators skip the no-load test to save time and proceed directly to material feeding. If foreign objects remain inside the mixer or the gearbox lacks lubrication, this may result in minor damage such as liner wear or, worse, burning out the main motor.
Key Points of Operation During the Production Process
1. Sequence and precision control of materials
The standard sequence for adding materials is: aggregate → cement/powdered coal ash → water → admixture. The core logic of this sequence is: adding aggregate first can prevent cement from directly adhering to the inner wall of the mixer; adding admixture last can prevent it from being absorbed by the aggregate and reducing the water-reducing effect.
Operators should closely monitor the deviation between the actual value and the set value of each batch of measurement. If a bin exceeds the limit for two consecutive batches, the machine should be stopped immediately for troubleshooting instead of covering up the problem with “manual feeding”.
2. Control of mixing time
The mixing time is not necessarily longer the better. Taking a double-shaft mixer as an example:
- Dry mixing time: 15-20 seconds (to allow the aggregate and cementitious materials to be preliminarily mixed);
- Wet mixing time: 25-35 seconds (after adding water, to fully mix).
Insufficient mixing will result in inconsistent concrete strength; excessive mixing will increase aggregate wear, raise concrete temperature, and accelerate slump loss. It is recommended to determine the optimal time through trial mixing within the parameter range provided by the equipment manufacturer based on the concrete grade and type of admixture.
3. Connection between unloading and transportation
The unloading after mixing should be completed within 15-20 seconds. During the unloading process, observe the uniformity of the concrete mixture. The mixing transport vehicle should be positioned in advance to avoid “waiting for materials while the machine is idle”, which can cause the concrete to remain in the mixer for an extended period.
4. Online monitoring of slump
Indirectly judge the consistency of the concrete through the mixing current or torque: an abnormal increase in current indicates that the concrete is too dry, and it should be immediately checked for changes in the moisture content of the aggregate (after rain, the moisture content of the aggregate can increase by 3% to 5%, and the addition amount must be adjusted synchronously).
Common Fault Diagnosis and Emergency Response Measures
| Fault phenomenon | Possible cause | Disposal method |
|---|---|---|
| Inaccurate measurement | Sensor drift, material accumulation in hopper | Stop the machine, reset and calibrate, clean the accumulated material in the hopper |
| Unsealed discharge door | Sealing strip worn out, insufficient cylinder pressure | Replace the sealing strip, adjust the cylinder pressure |
| Deviation of conveyor belt | Uneven tension, worn idler rollers | Adjust the tensioning device, replace the damaged idler rollers |
| Axle jamming of mixer | Excessive downtime, not cleaned in time | Follow the manufacturer’s procedures for cleaning, avoid hard knocking |
| Abnormal addition agent measurement | Chromatographic crystallization blockage | Flush the pipeline with warm water, check the filter |
Emergency handling principles: Any abnormal situation must be stopped first before any handling can be carried out. It is strictly prohibited to reach into the mixer or belt area while the equipment is in operation. In case of electrical failure, the main power supply must be cut off first before conducting any troubleshooting. Do not attempt to repair while the equipment is energized.
Daily Maintenance
Concrete mixing stations must be properly maintained to extend their service life.
1. Daily Maintenance
Rinse the interior of the mixing machine to remove residual concrete; inspect the discharge door seal and cylinder; clean the material accumulation in the weighing hopper to ensure accurate measurement.
2. Weekly Maintenance
Check the wear of belt joints and idler rollers; lubricate all bearings and hinges; check the air compressor filter and oil level.
3. Monthly Maintenance
Check the wear of the mixing arm and liner, and replace the liner when its thickness is less than 1/2; calibrate all weighing sensors; check if the electrical terminal connections are loose or overheating.
4. Annual Maintenance
Replace the lubricating oil for the reducer; conduct a comprehensive inspection of the steel structure welds and bolt fastening conditions; conduct a comprehensive overhaul of the hydraulic system.
Operator Training
It is essential to pay attention to the training of operators.
Concrete mixnig plant operation is not a simple job that can be mastered by just watching twice. Formal operator training should include:
- Theoretical Training: Foundation of concrete mix ratio, equipment working principle, electrical safety knowledge;
- Practical Training: Startup process, measurement calibration, fault simulation handling. It is recommended to last for no less than 40 hours;
- Safety Awareness Training: Equipment protection, high-altitude work, dust protection regulations.
Summary
From the pre-shift inspection to the accuracy of ingredient mixing, from emergency troubleshooting to maintenance cycles, every operational detail of the concrete mixing station will ultimately be reflected in the three figures of output, quality and cost. For the purchaser, choosing a equipment supplier that provides comprehensive operation training and after-sales support is just as important as selecting a high-performance concrete mixing station.