Closed-Loop Water Recycling High-Rate Thickener with 85-95% Water Recovery and

The NZS series high-rate thickener is a purpose-engineered solution for closed-loop water recycling in mineral processing operations, particularly those operating in environmentally regulated jurisdictions such as Colombia, where Law 1658 of 2013 and Minamata Convention compliance require demonstrable elimination of contaminated process water discharge. This high-rate thickener achieves 85-95% continuous water recycling by efficiently separating suspended solids from process slurries, producing a clarified overflow with less than 100 mg/L suspended solids suitable for direct recirculation to the grinding and flotation circuits, while simultaneously generating thickened underflow at 30-55% solids concentration. The system directly addresses Colombia’s Andean mining operations where proximity to ecologically sensitive watersheds demands zero-discharge process water management.

The NZS thickener employs a combination of gravity sedimentation enhanced by optimized flocculant conditioning and a mechanical rake mechanism that gently transports settled solids to the central underflow discharge cone. Feed slurry enters through a central feedwell designed to dissipate inlet energy and distribute the slurry uniformly across the tank cross-section, preventing short-circuiting and maximizing utilization of the full settling area. Flocculant dosing is precisely metered into the feedwell through an integrated preparation and dosing system, promoting controlled floc formation that enhances settling rates by factors of 5-15 compared to un-flocculated slurry. The VFD-controlled rake drive automatically adjusts rotation speed and torque output based on real-time bed pressure measurement, preventing rake bogging during feed solids excursions while maintaining consistent underflow density. The result is a reliable, automated water recycling system capable of 24/7 unattended operation.

• 85-95% Process Water Recycling: The NZS thickener consistently achieves overflow clarity of <50-100 mg/L TSS, enabling direct recirculation to the mineral processing circuit without intermediate filtration or polishing treatment. This level of water recovery reduces fresh water intake by 85-95%, critical for operations in Colombia’s seasonally variable water availability regions.
• High Settling Rate Design: The optimized feedwell geometry and integrated flocculant dosing system achieve settling rates 5-15 times faster than un-flocculated slurry, enabling the use of smaller diameter thickeners for a given volumetric throughput. The high-rate design reduces capital cost by 25-40% compared to conventional thickeners of equivalent capacity.
• Automated Rake Torque Control: The VFD-driven rake mechanism with real-time torque monitoring and automatic bed level sensing continuously adjusts rake rotation speed to maintain optimal underflow density while preventing overload conditions. The torque-rated drive system (5,000-80,000 N·m) can safely handle unexpected feed solids surges without operator intervention.
• Compact Footprint for Mountainous Terrain: The NZS thickener’s high-rate design requires a tank diameter 30-50% smaller than conventional thickeners for equivalent volumetric throughput, a critical advantage for Colombian Andean operations where flat land availability at altitudes of 2,500-4,000m is severely constrained by topography.
• Integrated Flocculant System: The skid-mounted flocculant preparation and dosing unit includes a dry flocculant powder feeder, aging tank with slow-speed agitation, and variable-speed metering pump. The system automatically adjusts flocculant dosage based on feed flow rate and solids concentration, maintaining optimal flocculation conditions across varying plant throughput.
• Corrosion-Resistant Construction for Acid Mine Drainage: All wetted surfaces are protected with a three-layer epoxy coating system tested to 3,000 hours chemical resistance, suitable for the mildly acidic (pH 4.5-6.5) process water conditions common in Colombian gold operations processing sulfide-bearing ores. Full stainless steel (304/316L) construction is available as an option for highly corrosive applications.

The NZS high-rate thickener is purpose-designed for water recovery in mineral processing operations where environmental regulations mandate closed-loop water circuits. Primary applications include process water recycling in gold gravity and flotation concentrators in Colombia’s Antioquia and Chocó departments, where proximity to Andean headwater streams requires zero contaminated discharge. The thickener is particularly effective in circuits where the combined STLB centrifugal concentrator and shaking table operations generate fine tailings (-200 mesh) requiring efficient solid-liquid separation for water recovery. Secondary applications include CCD (counter-current decantation) washing circuits in gold cyanidation plants, flotation tailings thickening ahead of dry stack filter presses, coal preparation plant fine refuse thickening, and mineral sands processing water recovery. The NZS is also deployed as a pre-thickener ahead of tailings filtration to increase filter press throughput by increasing feed solids concentration from 5-15% to 35-45%. The integrated flocculant system supports the use of both anionic and cationic polyacrylamide flocculants, selected based on the specific mineral surface charge characteristics of each process slurry.

Each NZS thickener undergoes factory pre-assembly verification of the rake mechanism and drive unit prior to shipment. The drive unit is factory-tested under load for a minimum of 2 hours with continuous monitoring of motor current, gearbox temperature, and bearing vibration. All tank sections are fabricated from prime-grade steel plate with full-penetration welds inspected via ultrasonic testing at critical joints. The equipment is shipped in modular sections: tank wall and floor panels in bolted segment crates, rake arms and central shaft in a purpose-built support frame, drive unit and bridge structure in a separate steel crate, and flocculant system on its own skid. Comprehensive documentation includes tank erection drawings with bolt torque specifications, rake mechanism assembly instructions, electrical and control wiring diagrams, and an operation and maintenance manual in both English and Spanish. Our commissioning team provides on-site supervision of tank erection, mechanical installation, flocculant system commissioning, and process performance optimization. A 12-month warranty covering all components from the date of successful commissioning is standard.