Zinc Stearate, Calcium Stearate, and Tri-Basic Lead Sulphate (TBLS) are fine, low-density materials widely used in plastics, PVC stabilizers, rubber processing, and coatings industries. These materials demand controlled Micronisation with narrow particle size distribution (PSD) to ensure proper dispersion, surface finish, and functional performance.
Due to their lightweight, dusty nature and flow sensitivity, conventional grinding systems often face challenges such as poor classification efficiency, dust losses, and inconsistent fineness.
The Air Classifying Mill (ACM) system offers a high-efficiency solution for producing uniform fine powder. Its integrated grinding and dynamic classification design ensures precise fineness control, high product recovery, minimal heat generation, and dust-free operation.
This application note outlines the process flow, system design, technical performance, and advantages of an ACM plant optimized for Zinc Stearate, Calcium Stearate, and TBLS grinding.
Design and Working Principle
The grinding system operates on a continuous, automated principle comprising the following stages:
Step 1: Material Feeding
Raw material is fed into the system through a feed hopper equipped with a magnetic grill to remove tramp metal.
A Rotary Airlock Valve (RAL) ensures:
- Uniform and controlled feeding
- Air sealing to maintain system pressure balance
- Prevention of backflow
Step 2: Impact Grinding in ACM Rotor
Material enters the grinding chamber where it is subjected to high-speed rotor action.
Grinding occurs due to:
- Impact of hammers/pins
- Shearing forces
- Particle-to-particle collision
- Air turbulence
The rotor creates strong airflow, keeping particles suspended and ensuring efficient size reduction.
Step 3: Air Classification
The ground material enters the dynamic classifier zone.
- Classifier wheel rotates at controlled speed (VFD driven)
- Fine particles pass through and exit with airflow
- Coarse particles are rejected and returned for regrinding
This ensures:
- Narrow particle size distribution
- Minimal oversize
- Consistent product quality
Step 4: Pneumatic Conveying & Cooling
The centrifugal fan generates airflow that:
- Conveys material to downstream system
- Maintains system temperature near ambient
- Enhances classification efficiency
For stearates and TBLS, this helps:
- Prevent agglomeration
- Maintain powder flowability
Step 5: Bag Filter & Product Collection
The air-material mixture enters the bag filter where:
- Powder is separated from air
- Fine particles are collected efficiently (>99%)
- Clean air is exhausted or recirculated
Pulse-jet cleaning ensures continuous operation without choking.
Step 6: Product Discharge
Collected powder is discharged via Rotary Airlock Valve into:
- Storage bins
- Packing systems
- Downstream processing
Model Variants
(Based on standard material properties and references)
| Variant | Model | Capacity (Approx.) | Target Fineness |
|---|---|---|---|
| ZA-30 | ACM 30 | 375 – 400 kg/hr | 99% < 44 microns |
| ZA-75 | ACM 75 | 750-900 kg/hr | 99% < 44 microns |
| ZA-100 | ACM 100 | 1100-1260 kg/hr | 99% < 44 microns |
️️ ⚠️Capacity may vary depending on material characteristics and fineness requirement.
Key Components
| Component | Function | Key Technical Feature |
|---|---|---|
| ACM Mill (Air Classifying Mill) | Performs grinding and classification | Integrated rotor + classifier, adjustable fineness (~44 micron) |
| Feed Hopper + RAL | Controlled material feeding | Uniform feed, airlock sealing, magnetic protection |
| Bag Filter System | Powder separation & dust control | >99% recovery, pulse-jet cleaning, continuous operation |
| Centrifugal Fan (C-Fan) | Airflow generation | Maintains system pressure, cooling, conveying |
| Control Panel (MCC/PLC) | System control & monitoring | VFD control, interlocks, automation ready |
| Ducting System | Interconnection of equipment | Optimized airflow, low pressure drop |
Key Features & Benefits
- Precise Fineness Control
- Consistent Product Quality
- High Product Recovery (>99%)
- Dust-Free Operation
- Energy Efficient System
- Reliable Continuous Operation
- Automation & Easy Control
- Low Maintenance Requirements
- Scalable Design
Dynamic classifier with VFD enables accurate control of particle size (~44 microns).
Closed-loop grinding and classification ensure stable PSD.
Efficient bag filter minimizes material loss.
Fully enclosed system ensures clean and safe working environment.
Optimized airflow and mill design reduce power consumption.
Designed for 24/7 industrial usage.
PLC/MCC system enables real-time monitoring and control.
Wear-resistant internals and self-cleaning filters reduce downtime.
Multiple ACM models available to match capacity requirements.
Applications
- PVC Stabilizers (TBLS)
- Plastic Additives (Zinc/Calcium Stearate)
- Rubber Processing Chemicals
- Paints & Coatings
- Specialty Chemical Powders
Model Variant
| Variant | Model | Capacity (Approx.) | Target Fineness |
|---|---|---|---|
| ZA-30 | ACM 30 | 375 – 400 kg/hr | 99% < 44 microns |
| ZA-75 | ACM 75 | 750-900 kg/hr | 99% < 44 microns |
| ZA-100 | ACM 100 | 1100-1260 kg/hr | 99% < 44 microns |
️⚠️Capacity may vary depending on material characteristics and fineness requirement.
Performance Parameters
| Characteristic | Specification |
|---|---|
| Feed Size | <1 mm |
| Final Fineness | ~44 microns (adjustable) |
| Bulk Density | 400 – 500 kg/m³ |
| Moisture | < 1% |
| Product Recovery | > 99% |
| Operating Temperature | Ambient |
| Noise Level | ~95 dB (without acoustic enclosure) |
Frequently Asked Questions (FAQ)
Q1: How do you ensure consistent fineness (~44 micron)?
A: Fineness is controlled through classifier speed (VFD) and airflow balance, ensuring precise and repeatable PSD.
Q2: Is the system suitable for handling dusty and light materials?
A: Yes. The enclosed system with high-efficiency bag filter ensures dust-free handling and high recovery.
Q3: Will material agglomerate during grinding?
A: No. Continuous airflow and low heat generation prevent agglomeration.
Q4: Can the system run continuously?
A: Yes. The system is designed for 24/7 operation with minimal maintenance.
Q5: How is contamination prevented?
A: Magnetic separators and closed-loop system prevent foreign particle contamination.