Essroc ExConTec
Project Overview
An Eastern USA cement company required a system to simultaneously transport crushed limestone from Quarry #2 to Cement Plant #1 on the upper belt strand, and distribute clinker from Plant #1 to Cement Plants #2 & #3 on the return belt strand. The most efficient solution was a single two-way conveyor — but achieving this demanded an unprecedented combination of the latest technologies.
The selected route was further complicated by topographical and right-of-way constraints that dictated nine relatively tight horizontal curves, each compounded by continuously changing vertical curves. The contract was entrusted to Continental Conveyor Ltd of Napanee, Ontario, and Thetford Mines, Quebec — a recognized leader in horizontally curving conveyor technology.
Technologies Featured
- Two-way conveying (limestone on upper strand, clinker on return strand)
- Nine horizontal curves with compound vertical curves
- Belt turnovers to use the thicker cover in either travel direction
- Full speed control via AC motors with variable frequency drives
- Tripper-type "Smart" booster intermediate drive (upper strand)
- Tripper-type "Natural" booster drive (return strand)
- Multiple discharge points along the return strand
ExConTec's Role
Following final design, Continental Conveyor Ltd engaged Dos Santos to perform a detailed comparative analysis using the ExConTec Computer Simulation and Analysis Program. The tight horizontal curves and numerous transient load conditions created significant tension control challenges, making rigorous simulation essential.
ExConTec offered several critical capabilities for this project:
- No intrinsic path limitations — analyzes any combination of curves, grades, and drive locations.
- Real-time load simulation — Load and Unload macro buttons model actual loading-on, trailing-off, and flow discontinuity conditions on either or both carrying strands.
- Curvature resistance accounting — expanded equations quantify the increased belt-line resistance of induced horizontal curvature.
- Discretionary calibration factors — permit the analysis model to reflect Continental Conveyor's own field experience and design philosophy.
Real-time analysis quickly revealed tension and power distribution under the full range of material flow conditions, confirming drive placement and control logic for the Smart booster to preclude local low-tension conditions at the upper strand.
System Parameters
| Parameter | Upper Belt Strand (Limestone) | Lower Belt Strand (Clinker) |
|---|---|---|
| Material | Limestone | Clinker |
| Design Rate | 1,320 t/h (1,455 STPH) | 420 t/h (463 STPH) |
| Belt Width | 1,067 mm (42") | |
| Belt Speed | 3.35 m/s (660 FPM) | |
| Net Lift | 46.8 m (153.7') | 14.7 m (48.1') |
| Max Lift | 57.8 m (189.8') | 22.6 m (74.1') |
| Overall Length | 2,752 m (9,029') | |
| Load Path Length | 2,748 m (9,014') | 2,225 m (7,299') |
| Horizontal Curves | 9 curves, R = 400–600 m (1,312–1,968') | 9 curves, R = 400–600 m (1,312–1,968') |
| Intermediate Discharges | — | 2 |
| Smart Booster Drive | 298 kW (400 HP) | — |
| Head Drive (Dual Pull) | 448 kW (600 HP) | — |
| Total Upper Drive Power | 746 kW (1,000 HP) | — |
| Natural Booster Drive | — | 149 kW (200 HP) |
| Total Lower Drive Power | — | 149 kW (200 HP) |
Key Highlights
- Recognized as the world's most technologically advanced single-flight conveyor at the time of installation
- Two-way conveying eliminates the need for separate dedicated systems for limestone and clinker
- Nine horizontal curves with compound vertical curves — a uniquely complex routing challenge
- Smart booster drive dynamically limits output to prevent low-tension conditions
- ExConTec analysis validated drive distribution and tension control logic across all transient load scenarios