Tailings management is one of the largest and most critical applications for slurry pumps in mining and mineral processing. Tailings are the waste materials remaining after valuable minerals are extracted, and must be safely transported, stored, and managed. This guide covers slurry pump selection for tailings management and disposal.
Tailings Overview
- Definition: Waste material after ore processing (ground rock, water, chemicals)
- Composition: Silica, alumina, silicate minerals, residual chemicals (cyanide, acid, lime)
- Volume: 90-98% of mined material becomes tailings (low-grade ore)
- Disposal methods: Tailings dam, paste fill, dry stacking, subaqueous disposal
- Environmental: Water management, dust control, dam safety, reclamation
- Regulatory: Strict regulations for dam safety and water quality
Tailings Slurry Characteristics
| Parameter | Conventional Tailings | Thickened Tailings | Paste Tailings |
|---|---|---|---|
| Solids % | 20-40% | 50-65% | 65-80% |
| SG | 1.2-1.6 | 1.5-1.8 | 1.8-2.2 |
| Viscosity | Low (water-like) | Medium | High (paste-like) |
| Particle size | <150μm (fine) | <150μm | <150μm |
| Abrasion | High (silica) | High | Very high |
| Flow behavior | Newtonian | Non-Newtonian | Yield stress |
| Transport | Pipeline (gravity/pump) | Pipeline (pump) | PD pump (high pressure) |
Pump Type Selection
Horizontal Centrifugal Slurry Pump
- Most common for conventional and thickened tailings
- Flow: 100-30,000 m³/h, head: 30-200 m
- Large passages, thick volute, hard metal or rubber-lined
- Material: high-chrome iron (HCCI), Ni-hard, or rubber-lined
- Advantages: high flow, handles fine solids, replaceable wear parts
- Multiple pumps in parallel (N+1 redundancy)
- For long-distance: booster stations every 2-5km
Vertical Slurry Pump
- For tailings sumps, thickener underflow, ponds
- Flow: 50-10,000 m³/h, head: 20-100 m
- Submerged or semi-submerged, no priming
- Material: HCCI or rubber-lined
- Advantages: handles variable level, no priming, compact
- For thickener underflow: vertical pump common (positive suction)
Positive Displacement (PD) Pump
- For paste tailings (high solids, high viscosity, high pressure)
- Types: piston, peristaltic, progressive cavity
- Flow: 10-500 m³/h, pressure: 20-200 bar
- For paste fill: piston pump (underground placement, long distance)
- Advantages: handles high viscosity, high pressure, consistent flow
- Limitations: lower flow, higher maintenance, pulsating
Water Pump (for Recirculation)
- For tailings pond water recovery and recirculation
- Flow: 100-10,000 m³/h, head: 20-100 m
- Material: cast iron, 316, or bronze
- Key: water recovery (reduce makeup, environmental)
Material Selection
Wetted Parts
| Material | Abrasion | Corrosion | Best For |
|---|---|---|---|
| High-chrome iron (HCCI) | Excellent | Fair | Silica tailings, high abrasion |
| Ni-hard | Excellent | Fair | General tailings |
| Rubber lining (natural) | Excellent (fine) | Good | Fine tailings, acid |
| Polyurethane | Excellent | Good | Abrasive, fine solids |
| 316 stainless | Fair | Excellent | Corrosive tailings (cyanide, acid) |
| Duplex stainless | Good | Excellent | Corrosive + abrasive |
| Cast iron | Poor | Poor | Clean water only |
Corrosion Considerations
- Cyanide tailings: alkaline (pH 10-11), toxic
- Acid mine drainage (AMD): acidic (pH 2-5), high sulfate/iron
- For cyanide: use 316 or duplex, double seal or magnetic drive
- For acid: use 316, duplex, Hastelloy, or fluoroplastic
- Verify material compatibility with actual tailings chemistry
Design Considerations
Abrasion Resistance
- Tailings: high silica content (very abrasive)
- Fine particles: high velocity impact wear
- Wear rate ∝ velocity³ — keep velocity low (1.5-3 m/s)
- Material: HCCI or rubber-lined (fine tailings)
- Replaceable wear parts: volute liner, throatbush, impeller, wear plate
- Thick casing: 20-40mm (wear allowance)
- Monitor wear: performance curve shift, vibration, ultrasonic thickness
High Solids (Paste Tailings)
- Paste tailings: 65-80% solids, high viscosity
- Non-Newtonian: yield stress, shear thinning
- Centrifugal pumps: cannot handle paste (too viscous)
- PD pumps: piston (most common), peristaltic, progressive cavity
- High pressure: 20-200 bar (long-distance, underground)
- Key: handle viscosity, maintain flow, prevent blockage
- Pipeline: must maintain velocity above critical (prevent settling)
Long-Distance Transport
- Tailings pipeline: 1-30km (from plant to disposal)
- Multiple booster pumps in series
- Velocity: 1.5-3 m/s (above deposition, below wear threshold)
- Pipe: rubber-lined steel, HDPE, or thick-walled steel
- Key: maintain pressure, prevent settling, minimize wear
- Flush on shutdown: prevent blockage (water flush)
Tailings Dam Safety
- Pumps must be reliable (failure — overflow, dam breach risk)
- N+1 redundancy: one standby pump
- Dual power: utility + emergency generator
- Instrumentation: flow, pressure, level, vibration, alarms
- Emergency spillway: independent of pumps (gravity)
- Regulatory: dam safety inspections, emergency action plan
System Design
Tailings Pump Station
- Multiple pumps in parallel (N+1 redundancy)
- Suction tank: large, agitated (prevent settling)
- Booster stations: for long pipelines
- Instrumentation: flow, pressure, density, level, vibration
- VFD: optimize speed for variable flow
- Emergency: backup power, alarm, shutdown
Thickener Underflow
- Thickener: increases tailings concentration (30% → 50-65%)
- Underflow pump: removes thickened tailings
- Material: HCCI or rubber-lined
- Key: handle high solids, variable viscosity, reliable
- Positive displacement: for very high underflow density
Paste Fill System
- Paste tailings: 65-80% solids (for underground backfill)
- Mix: tailings + cement + water (if needed)
- Pump: PD (piston) for underground placement
- Pressure: 50-200 bar (long-distance underground)
- Key: handle paste, maintain flow, prevent blockage
- Environmental: reduces surface disposal, reclaims mine voids
Water Recovery
- Tailings pond: water decants and is recovered
- Recirculation pump: returns water to plant (reduce makeup)
- Key: water recovery (environmental, cost)
- Water treatment: remove chemicals (cyanide, acid) before reuse/discharge
Common Issues
- Excessive wear: Silica tailings, high velocity. Use HCCI/rubber, lower velocity, replaceable parts.
- Settling/blockage: Low velocity, high solids. Maintain velocity, agitate tanks, flush, large passages.
- Paste blockage: High viscosity, long pipeline. Use PD pump, proper gradation, flush, maintain velocity.
- Corrosion: Cyanide/acid tailings. Use 316/duplex/PTFE, double seal/mag drive, verify compatibility.
- Pipeline wear: High velocity, abrasive. Use rubber-lined/HDPE, lower velocity, rotate pipe.
- Seal failure: Abrasive/corrosive slurry. Use expeller/double seal, proper flush, monitor.
- Dam safety: Pump failure, power loss. N+1 redundancy, backup power, emergency spillway.
- Environmental: Water contamination, dust. Water recovery, lined pond, dust control, monitoring.
Procurement Recommendations
- Provide: tailings type, solids %, SG, particle size, chemistry (cyanide/acid), flow, head, distance
- For conventional tailings: specify horizontal slurry pump, HCCI or rubber-lined
- For thickened tailings: specify horizontal or vertical slurry pump, high-solids design
- For paste tailings: specify PD pump (piston/peristaltic)
- For sumps/thickener: specify vertical slurry pump
- For corrosive tailings: specify 316/duplex/PTFE, double seal or magnetic drive
- For water recirculation: specify horizontal split case
- Specify material per abrasion/corrosion (HCCI, rubber, 316, duplex, PTFE)
- Include N+1 redundancy for critical tailings pumps
- Include replaceable wear parts (impeller, volute, throatbush, wear plate)
- Include instrumentation: flow, pressure, density, vibration, level
- For long pipeline: specify booster stations and flush system
- Verify supplier has tailings management references
Related Industries
Tailings slurry pump principles apply to mining (all commodities), power generation (ash disposal), chemical processing (waste slurry), and wastewater (sludge disposal). The core principle — reliable transport and disposal of abrasive/corrosive waste slurry with proper materials, redundancy, and environmental compliance — is consistent across tailings management applications.