A large calcium carbonate producer faced a common problem. Its downstream plastic manufacturing customers had rapidly growing demand for its GCC filler. However, the existing batch-type high-speed mixer modification line could no longer keep pace with order volumes. The customer required an ultra-high throughput of 5 tonnes per hour while maintaining a stearic acid coating rate above 99% and an activation rate ≥98%. With traditional single- or dual-chamber mixing equipment, achieving such productivity and uniformity when processing ultra-fine powders was practically impossible.
The Solution: EPIC Powder CRM-6 Continuous Three-Roller Coating System
After laboratory trials, comparative testing, and an on-site assessment by our engineering team, EPIC Powder configured a continuous three-roller surface coating system for the customer. It’s centered on the CRM-6 model .
This system is purpose-designed for the continuous processing of solid/liquid modifiers like stearic acid. Its key technical principles are as follows:
1. Continuous Three-Chamber Vortex Coating Process
The CRM-6’s most distinctive design is its three internally arranged, triangular coating chambers. Each chamber is equipped with a set of high-speed rotors. Powder is precisely fed by a screw conveyor to the first chamber, where the high-speed rotors generate a powerful vortex flow. The powder and atomized stearic acid modifier then pass through high-speed turbulence across the three chambers in sequence, undergoing thorough shearing, collision, and de-agglomeration between particles. This three-chamber series process effectively eliminates the dead zones common in traditional equipment. It ensures every single particle receives a uniform monomolecular layer coating.
2. Precise Temperature and Dosing Control
In stearic acid modification, temperature control is critical. If it’s too low, and the stearic acid cannot melt sufficiently. If it’s too high, and it can cause powder discoloration or even modifier degradation. The CRM-6 integrates multi-stage, precise temperature control measures:
- Automatic Feeding: A variable-frequency metering screw steadily conveys the raw powder to a pre-heating unit.
- Modifier Dosing: Solid stearic acid is melted in an electrically heated dosing tank and automatically injected via a metering pump at a rate synchronized with the main material flow (typically 0.8–1.2% of powder weight).
- Core Modification: Inside the coating chambers, within the strong turbulence generated by rotors reaching tangential speeds of 60 m/s, stearic acid molecules undergo rapid chemisorption onto the surface of calcium carbonate particles, forming a stable, uniform organic coating layer.
- Post-Processing: The modified calcium carbonate powder is collected through a cyclone separation system, with an integrated classification step to remove any minimal soft agglomerates.
Thanks to the high-speed self-friction heating effect, the CRM-6 requires no independent heating or cooling units. Its compact structural design significantly reduces auxiliary equipment investment and daily operational energy consumption.
Core Results and Customer Benefits
After commissioning, the CRM-6 system demonstrated stable performance under full-scale production conditions:
| Parameter | Customer Requirement | CRM-6 Actual Performance |
|---|---|---|
| Throughput | ≥ 3.0 t/h | 3.2 t/h |
| Coating Rate | ≥ 98% | 99.2% |
| Oil Absorption | ≤ 18 g/100g | 16.5 g/100g |
| Activation Rate | ≥ 98% | 99.5% (full floatation by water method) |
Data source: On-site sampling and testing reports from the customer’s facility.
These key indicators directly translated into downstream benefits. For instance, in a corresponding case, a PVC pipe manufacturer used calcium carbonate treated with the same modification process in its extrusion lines. The filler surface changed from hydrophilic to oleophilic, oil absorption decreased, and the amount of plasticizer needed during processing was reduced. Both the tensile strength and impact resistance of the pipes were significantly improved.
Overall, the core value delivered by the CRM-6 for this customer included:
- Doubled Production Capacity: Continuous operation replaced batch processing, enabling 24/7 uninterrupted production. A single CRM-6 unit can match the throughput requirements of a large GCC production line.
- High-Efficiency Modifier Utilization: A coating rate as high as 99.2% means near-theoretical stearic acid utilization efficiency, effectively lowering the cost per ton of modified product.
- Enhanced End-Product Performance: Low oil absorption and high activation rate give the modified calcium carbonate better compatibility, dispersibility, and mechanical performance in PVC pipes, PP injection-molded parts, and other plastic applications.
Why the CRM-6 is the Ideal Choice for Calcium Carbonate Surface Modification
The CRM-6 three-roller coating machine successfully helped this calcium carbonate producer resolve the fundamental conflict between high throughput and premium quality. Its three interconnected coating chambers, precise temperature control system, and continuous material handling process have proven their unique advantages in large-scale stearic acid coating modification.
EPIC Powder
EPIC Powder Machinery (Qingdao) Co., Ltd. is a technology-driven manufacturer with over 20 years of expertise in powder processing equipment and process development. The company provides CE-certified, customized solutions, covering jet mills, mechanical mills, air classifiers, ball mill classification lines, and surface modification systems. Guided by the philosophy of Equipment + Process + Service, EPIC Powder is dedicated to helping global customers transform ordinary powders into high-value functional materials.
Interested in seeing how the CRM-6 can adapt to your powder and production line needs? 👉 Contact us for a customized solution.
“Thanks for reading. I hope my article helps. Please leave a comment down below. You may also contact EPIC Powder online customer representative Zelda for any further inquiries.”
— Jason Wang, Engineer