Background
Guinea holds approximately one-third of the world's known bauxite reserves. A bauxite mining and export operation in the Boké region was specifying conveyor belts for a new mine-to-port conveyor system carrying crushed bauxite from the mine to the Kamsar export port — a total conveying distance of approximately 12 kilometers via multiple conveyors.
The system included: - Three overland conveyors totaling approximately 11km - A series of shorter in-plant conveyors at the crushing and screening facility - Port shiploading conveyors at Kamsar
The project engineering team requested belt specifications for all sections.
Material and Environment Characteristics
Bauxite ore properties: Guinea bauxite is a lateritic ore — relatively soft (hardness 1–3 Mohs), with high clay content and high moisture (30–40% moisture content during wet season). It is sticky and cohesive when wet, tending to adhere to belt covers and causing carryback.
Climate: Boké region has a tropical climate with a pronounced wet season (May–October) with extremely high rainfall (over 2,000mm annually) and a dry season. Outdoor conveyors must handle both wet-season operating conditions (continuous rainfall, high humidity) and dry-season conditions (dust, heat, UV).
Port environment: Kamsar port is a coastal environment with saltwater exposure and high ambient humidity year-round.
Belt Specification by Conveyor Section
Overland conveyors (ST ratings):
The 11km total overland distance required steel cord belts for the trunk sections. Tension calculations based on lift profiles and tonnage (4,500 t/h design) gave:
- Longest trunk (6.2km with 180m net lift): ST2000, 1,400mm wide
- Second trunk (3.1km, flat): ST1250, 1,400mm wide
- Third section (1.7km, slight decline): ST1000, 1,200mm wide
All overland belts specified with full tropical weatherproof covers — UV-stabilized, ozone-resistant EPDM compound — given the outdoor exposure in both wet and dry seasons.
In-plant conveyors: - EP200–EP315, 800–1,000mm wide - Tropical-grade M24 covers - Anti-stick surface texture on top cover to reduce wet bauxite adhesion
Port shiploading conveyors: - ST1600, 1,400mm wide for main shiploader belt - Weatherproof coastal-grade covers (higher ozone resistance for salt air environment)
Carryback Management
Given wet bauxite's stickiness, the scraper specification was given significant attention:
- Primary and secondary scrapers specified on all loaded conveyors
- Polyurethane scraper blades (better material release for sticky laterite than tungsten carbide)
- Belt washing systems specified at head ends of overland conveyors — water wash is more effective than scrapers alone for extremely sticky wet bauxite
- Self-cleaning rubber disc return idlers specified throughout to prevent buildup on return idlers
Outcome
The system commissioned successfully. During the first wet season of operation, carryback was within expected levels — the combination of PU scrapers and belt wash systems kept the return run clean enough to prevent the return idler buildup that was a known problem at similar operations.
The overland belt covers showed no UV or ozone degradation at the 18-month inspection during the dry season. The coastal shiploader belt showed no saltwater-related deterioration.
Key Points
Bauxite is a carryback-intensive material. Wet sticky laterite is one of the most challenging materials for belt cleanliness. Plan for it explicitly in the scraper and belt wash specification — don't treat it as an afterthought.
Tropical weatherproof covers are essential, not optional, for Guinea outdoor installations. The combination of high rainfall in the wet season and intense UV in the dry season demands covers formulated for both extremes.
Port conveyors in salt air environments need specific ozone resistance. Coastal saltwater environments accelerate rubber degradation. Specify covers accordingly for any conveyor within 5km of the coast.
Elephant Rubber supplied the conveyor belts for multiple sections of this project.