An inline or continuous multi mill is a frame-mounted multi mill positioned within a continuous or semi-continuous manufacturing line receiving granule continuously from upstream process equipment (FBP, RMG, roller compactor, vacuum transfer) and discharging sized product continuously to the downstream vessel, IBC, or process without manual intervention. Processing 5–2,000 kg/h in direct-to-container or recirculation loop configurations with screen apertures of 0.5–25 mm, it integrates directly into ICH Q13 continuous solid dosage lines, FBP discharge milling loops, roller compactor ribbon milling systems, and high-throughput direct compression tablet press feed preparation.
Material is delivered continuously to the mill inlet by a gravimetric loss-in-weight feeder, pneumatic transfer line, or FBP/RMG discharge chute feed rate is matched to the mill’s rated throughput by a PLC ratio controller to prevent overloading. The impeller (700–3,000 RPM, VFD) continuously forces material through the screen; sized product discharges continuously by gravity into the downstream vessel. In a recirculation loop configuration, the mill outlet feeds directly into a continuous blender or tablet press while an inline sieve returns oversized particles to the mill inlet for re-milling the loop operates until the full batch meets PSD specification. Frame height is adjustable to suit different downstream vessel heights; the mill body tilts for rapid screen change without stopping adjacent equipment.
Challenges
Feed Rate Surge from FBP or RMG Batch Discharge Overloading Mill
Batch-mode upstream equipment discharges in a short surge that exceeds continuous mill capacity blockage.
Screen Blinding During Long Continuous Runs with Moist or Sticky Feed
Extended continuous processing of moist granule progressively blinds the screen throughput falls below line rate.
Product PSD Drift During Continuous Run from Blade Wear
Gradual blade edge wear shifts D90 upward during long campaigns out-of-specification product generated.
Recirculation Loop Instability Oversized Particles Accumulating in Loop
If mill capacity is below inline sieve rejection rate, oversized accumulates in loop system stalls.
Line Integration Mill Speed Must Respond to Upstream PSD Variation in Real Time
Upstream process variations (granule density, moisture) require real-time impeller speed adjustment.
Solutions
- Surge Buffer Hopper Between FBP/RMG and Mill Inlet (60–120 s Capacity): Buffer hopper smooths batch discharge surge to steady continuous rate mill never sees peak surge.
- Timed Air-Pulse Screen Cleaning (Compressed Air, every 20–30 min, 3 bar): Scheduled air pulse from inside the mill body clears screen surface prevents blinding during long runs.
- Inline Laser Particle Size Analyser on Mill Discharge (D90 Feedback to VFD): Real-time PSD sensor adjusts impeller speed to maintain D90 within specification as blades wear.
- Recirculation Loop Capacity Matched at 3× Maximum Inline Sieve Rejection Rate: Mill sized for 3× expected recirculation load loop stable even at highest oversized rejection rate.
- PLC Speed Ratio Control: Impeller RPM = f(Upstream Granule Moisture, Feed Rate): Feed moisture signal from NIR probe adjusts impeller speed setpoint automatically tight PSD maintained.
Applications
- Pharmaceutical (Continuous Mfg.): ICH Q13 continuous tablet mfg. inline milling between continuous granulator and continuous blender.
- Pharmaceutical (FBP Discharge): Fluid bed granulator discharge milling eliminates batch milling step, direct to blending IBC.
- Pharmaceutical (Roller Compaction): Continuous ribbon milling after roller compactor closed-loop PSD control to tablet press.
- Food & Beverage: Continuous inline extrude milling, instant food granule sizing, breakfast cereal size control.
- Chemical: Continuous catalyst ribbon milling, specialty chemical compaction ribbon sizing.
Models & Capacities
| Type 3DÂ Inline / Continuous Multi Mill: Models & Capacities | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Model | Scale | Throughput [kg/h] | Screen Aperture [mm] | Impeller Speed [RPM] | Motor [kW] | Screen Orientation | Inlet Type | Discharge Type | Frame Height Adjust [mm] | L × W × H [mm] | Weight [kg] |
| MM-IL-LAB | Lab/Pilot | 5–30 | 0.5–15 | 700–3,000 VFD | 1.5 | Horizontal | Gravity / Chute | Direct gravity | ±100 manual | 560×420×800 | 65 |
| MM-IL-PIL | Pilot | 20–100 | 0.5–15 | 700–3,000 VFD | 3.0 | Horizontal | Gravity / Chute | Direct gravity | ±100 manual | 760×540×1,000 | 130 |
| MM-IL-300 | Production | 80–300 | 0.5–20 | 700–3,000 VFD | 7.5 | Horiz/Vert | Gravity / Feeder | IBC / Bin | ±150 hydraulic | 1,000×700×1,300 | 260 |
| MM-IL-700 | Production | 200–700 | 0.5–20 | 700–2,500 VFD | 15 | Horiz/Vert | Gravity / Feeder | IBC / Bin | ±150 hydraulic | 1,300×900×1,650 | 480 |
| MM-IL-1000 | Production | 350–1,000 | 0.5–25 | 700–2,000 VFD | 22 | Horiz/Vert | Gravity / Pneumatic | IBC / Silo | ±150 hydraulic | 1,600×1,100×2,000 | 780 |
| MM-IL-1500 | Production | 500–1,500 | 0.5–25 | 700–1,800 VFD | 30 | Horiz/Vert | Gravity / Pneumatic | IBC / Silo | ±150 hydraulic | 1,950×1,350×2,400 | 1,150 |
| MM-IL-2000 | Large Prod | 800–2,000 | 0.5–25 | 700–1,800 VFD | 45 | Horiz/Vert | Gravity / Pneumatic | Silo / Direct | ±150 hydraulic | 2,350×1,600×2,800 | 1,650 |