Turmeric is a widely used spice and functional ingredient in food, nutraceutical, and pharmaceutical industries. It is processed from whole dried turmeric fingers and requires controlled multi-stage grinding to achieve uniform fine powder with desired color, aroma, and curcumin retention.
Due to its fibrous structure, relatively hard form, and oil content, direct fine grinding of whole turmeric in a single-stage system is inefficient and can lead to excessive load on the mill, higher energy consumption, and inconsistent particle size distribution (PSD).
To overcome these challenges, a two-stage grinding approach is adopted:
- Stage 1: Coarse grinding using PII Mill (Hammer Mill)
- Stage 2: Fine grinding using Air Classifying Mill (ACM)
This combination ensures efficient size reduction, stable mill operation, and improved overall system performance.
Additionally, turmeric is heat-sensitive and prone to loss of volatile compounds and color degradation if not processed under controlled conditions. Therefore, the integrated system is designed to minimize heat generation and maintain product quality.
The complete system — comprising cleaning, coarse grinding, fine grinding, classification, and efficient product recovery — provides a high-performance, hygienic, and dust-free solution for turmeric powder production.
This application note outlines the process flow, system design, technical performance, and advantages of a turmeric cleaning and grinding plant using a PII + ACM based system.
Design and Working Principle
The system operates in a continuous process comprising cleaning, feeding, grinding, classification, and product collection stages:
Step 1: Raw Material Cleaning
Whole turmeric fingers are fed into the cleaning system which may include:
- Vibro feeder / grader
- Destoner / magnetic separator
This ensures removal of:
- Dust and foreign particles
- Stones and metal contaminants
Step 2: Coarse Grinding (Pre-Grinding – PII Mill)
Cleaned turmeric is fed into a PII Mill / Hammer Mill for primary size reduction.
Grinding occurs due to:
- High-speed impact of hammers
- Breaking of fibrous turmeric structure
This stage reduces size from:
- Whole fingers → coarse granules (~2–5 mm)
Benefits of this stage:
- Improves ACM efficiency
- Reduces load on fine grinding mill
- Ensures uniform feed to ACM
- Enhances overall system capacity
Step 3: Controlled Feeding to ACM
Coarse ground material is fed via:
- Feed hopper
- Rotary Airlock Valve (RAL)
This ensures:
- Uniform feed rate
- Air sealing
- Stable mill operation
Step 4: Fine Grinding in ACM Mill
Material enters the ACM where fine grinding occurs due to:
- High-speed rotor impact
- Shearing action
- Particle-to-particle collision
The airflow:
- Keeps particles suspended
- Prevents excessive heat buildup
- Maintains turmeric color & aroma
Step 5: Dynamic Air Classification
- Fine particles pass through classifier
- Coarse particles are rejected and recirculated
This ensures:
- 95–98% < 300 microns
- Narrow PSD
- Consistent product
Step 6: Pneumatic Conveying
Centrifugal fan:
- Transports material
- Maintains temperature
- Improves classification efficiency
Step 7: Cyclone & Bag Filter Collection
Cyclone Separator:
- Primary separation of product
Bag Filter:
- Fine particle recovery (>99%)
- Clean air discharge
Step 8: Final Screening & Discharge
- Product discharged via RAL
- Passed through vibro shifter
Ensures:
- Uniform particle size
- Removal of oversize
Model Variants
| Variant | Model | Capacity | Fineness |
|---|---|---|---|
| TG-500 | ACM Based System | 450-500 kg/hr | 95% < 300 microns |
⚠️ Capacity may vary based on moisture, feed size, and turmeric quality.
Key Components
| Component | Function | Key Technical Feature |
|---|---|---|
| Cleaning System | Removal of impurities | Vibro feeder, destoner, magnetic separator for dust, stones & metal removal |
| PII Mill (Hammer Mill) | Coarse grinding | Pre-size reduction of turmeric fingers to ~2–5 mm for efficient ACM operation |
| Feed Hopper + RAL | Controlled material feeding | Uniform feed, airlock sealing, prevents backflow |
| ACM Mill (Air Classifying Mill) | Fine grinding & classification | Integrated rotor + classifier, adjustable fineness (95–98% < 300 micron) |
| Cyclone Separator | Primary Powder separation | Reduces load on bag filter, improves system efficiency |
| Bag Filter System | Fine powder collection & dust control | >99% recovery, pulse-jet cleaning, continuous operation |
| Vibro Shifter | Final Screening | Ensures uniform particle size, removes oversize |
| Centrifugal Fan (C-Fan) | Airflow generation | Maintains system pressure, cooling, pneumatic conveying |
| Ducting System | Interconnection of equipment | Optimized airflow, low pressure drop |
| Control Panel (MCC/PLC) | System control & monitoring | VFD control, interlocks, automation ready |
Key Features & Benefits
- Controlled Grinding for Heat Sensitive Product
- Uniform Particle Size Distribution
- High Product Recovery (>99%)
- Hygienic & Food-Grade Design
- Dust-Free Operation
- Energy Efficient System
- Continuous Operation
- Automation Ready
- Low Maintenance
Maintains color, aroma, and curcumin content.
Dynamic classifier ensures consistent fineness.
Efficient cyclone + bag filter system.
SS contact parts ensure contamination-free processing.
Fully enclosed system ensures clean working environment.
Optimized airflow reduces power consumption.
Suitable for industrial 24/7 usage.
PLC-based system with VFD control.
Robust design with minimal wear parts.
Applications
- Turmeric powder processing
- Spice grinding plants
- Food processing industries
- Ayurvedic & nutraceutical products
Model Variants
| Variant | Model | Capacity | Fineness |
|---|---|---|---|
| TG-500 | ACM Based System | 450-500 kg/hr | 95% < 300 microns |
Performance Parameters
| Characteristic | Specification |
|---|---|
| Feed Material | Whole turmeric |
| Feed Size | 20–50 mm |
| Final Fineness | 95–98% < 300 microns |
| Capacity | ~500 kg/hr |
| Moisture | < 10% recommended |
| Product Recovery | > 99% |
| Operating Temperature | Controlled (near ambient) |