How to automate the rCB packaging and grinding process

Automation for rCB grinding‑packaging workflow aims to reduce manual intervention, stabilize particle‑size quality, lower fugitive dust, cut labor cost, and realize continuous unattended operation for tire pyrolysis char processing. It covers raw‑material feeding, grinding‑classification closed‑loop control, powder conveying, silo buffer storage, automatic bulk‑bag packaging, safety interlock and data logging. Based on rcb‑mill.com practical engineering experience, automation can be implemented in incremental stages: basic PLC automation, semi‑automatic closed‑loop control, and advanced full‑automatic intelligent control.

1. Overall automation architecture for grinding & packaging section

Whole‑system divided into functional sub‑systems:

1. Pretreatment feeding automation (char silo, screw feeder, magnetic separation, screening)
2. Grinding‑classification host automatic control (ACM / jet mill, turbine classifier, fan, air seal)
3. Powder pneumatic / mechanical conveying automatic control
4. Finished‑product silo level monitoring & material distribution control
5. Automatic bulk‑bag packaging station
6. Safety interlock system, alarm & historical data recording
7. HMI central operation interface

Core principle: negative‑pressure interlock, sequence start‑stop, fault chain stop, material level linkage, quality‑feedback closed‑loop adjustment.

2. Automate the grinding‑classification process

2.1 Sequence interlock startup‑shutdown logic

rCB grinding system cannot start each unit randomly. PLC enforces strict sequence:
Startup sequence: dust‑collector fan → classifier shaft gas‑seal air supply → classifier motor → grinding host → feeding screw feeder.
Shutdown sequence: stop feeder → empty residual material inside mill → stop grinding host → stop classifier → delay stop fan → stop seal‑air.
Interlock protection: if fan or shaft gas‑seal pressure is abnormal, feeding is forced to stop, prevent powder leakage and bearing damage.

2.2 Key analog monitoring points for grinding section

Install transmitters connected to PLC:

• Motor current: grinding host, classifier, feeder, fan
• Differential pressure: grinding chamber, classifier inlet‑outlet, pulse dust‑collector
• Shaft‑end gas‑seal air pressure (critical for rCB; trigger alarm and stop feeding when pressure drops below threshold)
• Bearing temperature of grinding rotor and classifier wheel
• Vibration sensor on classifier housing (prevent unbalance caused by caking)
• Silo material level for feed silo and recirculation material

All parameters show on HMI, with high‑low limit alarm.

2.3 Two automation levels for grinding control

Level‑1: Basic fixed‑parameter automation (low‑cost retrofit for existing line)

Feeder speed, classifier frequency, fan air volume set manually on HMI. System only executes sequence start‑stop, over‑limit alarm and safety interlock. Suitable for stable‑quality pyrolysis char with little property fluctuation.

Level‑2: Closed‑loop quality‑feedback automatic control (recommended for commercial rCB plant)

Add optional online PSD particle‑size analyzer installed at finished‑powder outlet.

• When D97 drifts higher (coarser powder): PLC automatically raises classifier wheel speed, or slightly reduces feeder rate.
• When D97 becomes too fine and yield drops: lower classifier speed or increase feeding within safe working window.
• Cooperate with differential‑pressure signal of grinding chamber to judge caking / blockage risk.

Note: Online PSD instrument increases investment. Many projects adopt semi‑closed‑loop: lab offline test data input manually to adjust set‑points.

2.4 Jet‑mill special automation items

• Compressed‑air pressure & dew‑point monitoring, interlock feeding stop when air quality fails.
• If inert‑gas nitrogen circulation: online oxygen‑content monitoring, interlock shutdown when oxygen exceeds safety threshold.

3. Automate rCB conveying and finished‑product silo system

1. Silo continuous level sensor (radar level meter, avoid vibration‑type level switch which is easy to stick by rCB powder). Realize automatic material‑distribution between multiple finished‑product silos.
2. Dense‑phase pneumatic conveying / tubular drag conveyor automatic running: pressure monitoring, blockage detection, automatic blockage‑blow‑back logic.
3. Silo‑top dust‑collector automatic pulse‑jet cleaning controlled by differential pressure, not fixed‑time cycle; adapt to sticky rCB powder characteristics.
4. Rotary airlock valve running status monitoring, interlock with silo level. Prevent empty running or material overflow.

4. Automate rCB packaging section (bulk‑bag FIBC / big‑bag station)

rCB fine powder is low‑bulk‑density, dusty; manual small‑bag filling should be avoided for automated plant. Mainly adopt automatic bulk‑bag packaging.

Core automatic functions of bulk‑bag filling station

1. Automatic bag‑clamping mechanism: clamp the big‑bag spout tightly, form sealed negative‑pressure filling hood, eliminate fugitive dust during filling.
2. Automatic weighing closed‑loop control: load‑cell sensor under filling frame. Pre‑set target weight (e.g. 500 kg / 1000 kg).
   • Fast feeding → slow fine feeding → automatic cut‑off when reaching target weight.
3. Automatic bag‑inflation: inflate empty big‑bag before filling to expand bag body, prevent rCB powder compacting and arching.
4. Dust‑extraction interlock: negative‑pressure dust‑extraction hood automatically opens when filling starts; stop when filling completes.
5. After filling completion: automatic release bag clamp, prompt forklift to take away full bag.
6. Optional upgrades