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A tailing slurry pump handling more than 60% solids by weight is not simply pumping “thicker water.” At this concentration, a small change in particle-size distribution, clay content, mineral density, temperature, or water chemistry can produce a large change in viscosity, yield stress, settling behavior, pipeline loss, and restart pressure.
The pump must therefore be selected as part of a complete transport system: thickener or feed tank, suction line, pump, check valves, pipeline, instruments, flushing arrangement, control logic, and shutdown procedure. This guide explains what “above 60% by weight” means, why abrasive tailings become difficult to move, when a piston diaphragm design should be evaluated, and what operating data is required before a model is selected.
Solids concentration by weight, often written as Cw or wt%, is the mass of dry solids divided by the total mass of solids plus liquid. A slurry at 60% solids by weight contains 60 kg of dry mineral solids and 40 kg of liquid in every 100 kg of mixture.
Weight concentration is not the same as volume concentration. Mineral particles are usually much denser than water, so 60% solids by weight may represent a considerably lower solids volume fraction. The distinction matters because pipeline occupancy, particle interaction, rheology, and settling are influenced by both mass and volume.
An approximate mixture density can be calculated from:
Slurry density = 1 / (Cw / solids density + (1 − Cw) / liquid density)
The example below assumes mineral solids with a specific gravity of 2.70 and water at 1.00 t/m³. It illustrates the conversion only; laboratory density and rheology measurements should be used for final design.
| Solids by weight | Approximate slurry density | Approximate solids by volume | Design implication |
|---|---|---|---|
| 60% | 1.61 t/m³ | 35.7% | Dense slurry; friction, wear, and settling must be checked. |
| 65% | 1.69 t/m³ | 40.7% | Particle interaction and yield stress may rise quickly. |
| 70% | 1.79 t/m³ | 46.3% | May behave as high-density slurry or paste, depending on fines and clay. |
There is no universal point at which every tailings stream becomes paste. Two samples at 65 wt% can behave very differently if one contains rounded sand and the other contains fine clay-rich particles. A pump supplier needs the complete particle-size distribution and rheology curve, not concentration alone.
As solids crowd together, the slurry may require a minimum shear stress before it starts to move. This yield stress affects tank discharge, suction-line loss, pipeline friction, and the pressure needed to restart after a stoppage. A five-percentage-point increase in weight concentration can create far more than a five-percent change in pumping difficulty.
A dense slurry does not flow into a pump as easily as water. A long or undersized suction line, low thickener level, restrictive valve, sharp elbow, trapped air, or settled bed can starve the pump. Increasing discharge capability does not correct poor suction. The feed arrangement must provide adequate inlet pressure and a short, continuously rising, drainable path where practical.
Tailings particles damage wet-end parts through sliding abrasion, impact, turbulence, and sometimes corrosion-abrasion. Excessive velocity can accelerate wear in elbows, valve seats, manifolds, liners, and reducers. Velocity that is too low, however, allows coarse particles to settle. The pipeline must operate inside a project-specific transport window rather than at a generic “safe” velocity.
When a concentrated tailings line stops, coarse solids may form a stationary bed while fine material consolidates. Restart pressure can then exceed normal operating pressure. A controlled water or low-density slurry flush, drain points, bypasses, and a defined maximum stoppage time are part of the pump system—not optional operating notes added later.
No. “Tailing slurry pump” describes the duty, not a single mechanism. Centrifugal slurry pumps, hydraulic piston diaphragm pumps, hose piston diaphragm pumps, and special paste-transfer pumps can all be suitable in the right operating range.
| Pump type | Where it can fit | Main high-solids concern |
|---|---|---|
| Heavy-duty centrifugal slurry pump | High flow, shorter distance, moderate head, slurry with manageable rheology. | Flow changes with system resistance; high speed, staging, wear, or sealing-water demand may become limiting. |
| Hydraulic piston diaphragm pump | High pressure, controlled flow, continuous tailings pipelines, thickener underflow. | Check-valve passage, diaphragm material, suction pressure, pulsation control, and capital complexity must be engineered. |
| Hose piston diaphragm pump | Abrasive or corrosive high-solids transfer where isolation and a linear hose path are valuable. | Hose fatigue, chemical compatibility, pressure rating, maximum particle size, and maintenance access must be confirmed. |
| Special paste or hydraulic piston pump | Very high yield stress, coarse particles, cemented backfill, or non-flowing feed. | Requires purpose-designed feed, transfer tubes or valves, and pipeline restart analysis. |
A centrifugal pump should not be rejected simply because concentration exceeds 60 wt%. It may still be the most economical choice for a short, high-flow duty with favorable particle distribution and low yield stress. Conversely, a positive-displacement pump should not be selected only because it can generate pressure. Valve clearances, diaphragm or hose materials, inlet conditions, and the entire pipeline must match the actual slurry.
A hydraulic piston diaphragm slurry pump is especially worth comparing when several of the following conditions occur together:
In a piston diaphragm pump, the piston displaces clean hydraulic oil and the diaphragm separates that oil from the slurry. This protects the piston and power end from direct abrasive contact. Displacement is linked to speed and stroke volume, so flow remains comparatively predictable while the pressure changes with pipeline resistance. For a more detailed mechanical explanation, see how a piston diaphragm pump works.
A hose piston diaphragm pump provides another positive-displacement option. TOMINE’s double-hose layout is designed to create two barriers between slurry and hydraulic oil, detect a hose failure, and operate without high-pressure sealing water. The linear hose path may also reduce dead zones, but hose material, fatigue duty, pressure, temperature, chemistry, and particle size still require project-specific confirmation.
Thickener underflow concentration changes with ore type, flocculant dose, bed level, rake condition, and production rate. Density and flow instruments should be used to manage those changes. The feed or charge pump must be controlled so that the main positive-displacement pump receives adequate, stable inlet pressure without overpressurizing its suction manifold.
TOMINE’s iron-ore tailings conveying solution shows a thickener-underflow arrangement in which concentration, flow, charge-pump speed, and main-pump inlet pressure are coordinated. This is more useful than selecting the main pump in isolation.
Positive-displacement tailings pumps use suction and discharge check valves. Maximum particle size, the coarse tail of the size distribution, oversize contamination, particle shape, and settling tendency affect valve lift, impact, blockage, and seat wear. Screens or upstream classification may be required, but they must not create an unreliable restriction in the feed path.
The lower limit must prevent unacceptable deposition; the upper limit must avoid excessive abrasion, pressure loss, and energy use. The correct window depends on pipe diameter, particle-size distribution, solids density, concentration, rheology, pipe inclination, and operating mode. Use measured slurry data and hydraulic modelling. Do not copy a velocity from another mine without checking whether the tailings are comparable.
A positive-displacement pump must never run against a closed discharge path. The system needs correctly rated piping, pressure transmitters, relief protection, valve-position interlocks, pulsation control, emergency shutdown logic, and a defined safe destination for relieved slurry. Pressure ratings must cover normal operation, pulsation, transient events, and blocked-line conditions.
Provide flush-water connections, drain points, isolation, low-point access, and a procedure for controlled displacement of concentrated slurry. The required flush volume depends on pipeline geometry and the acceptable residual solids. If process water is scarce, the design should evaluate recovery and reuse rather than omitting the flush system.
Trend density, mass flow, suction pressure, discharge pressure, pump speed, motor load, hydraulic-oil condition, diaphragm or hose alarm status, dampener condition, and pipeline pressure at critical elevations. Trends show developing restriction or wear earlier than a single alarm. A rising pressure at constant flow and density can indicate deposition or a valve restriction; falling capacity at constant speed can indicate suction starvation or valve leakage.
Reduce solids feed according to the process procedure, displace high-density slurry with lower-density material or water, verify that critical sections are clear, stop the main pump, and then stop the charge system and agitation in the approved order. Record the line condition and expected restart window.
Do not immediately apply maximum motor speed to a potentially settled line. Check elapsed time, pressure decay, density, temperatures, valve positions, and the site’s blocked-line procedure. A consolidated bed may need staged flushing, drainage, or mechanical intervention. Restart pressure must remain within the pump, pipe, flange, valve, and relief-system ratings.
| Observed signal | Possible causes | Checks to make |
|---|---|---|
| Discharge pressure rises at constant flow | Higher density or yield stress, deposition, restricted valve, partially closed line valve. | Confirm density, rheology trend, valve positions, pipeline pressure profile, and flush condition. |
| Suction pressure falls or fluctuates | Low thickener level, feed-pump mismatch, blocked suction, air entry, excessive viscosity. | Inspect feed level, charge-pump speed, suction path, vents, and concentration. |
| Flow falls at constant pump speed | Check-valve leakage, gas entrainment, insufficient feed, hydraulic imbalance. | Compare cylinder balance, valve noise, suction pressure, oil system, and flow calibration. |
| Valve noise or rapid valve wear | Oversize particles, high impact velocity, wrong seat material, poor valve motion. | Sample PSD, inspect seat and valve, review speed and material selection. |
| Pulsation increases | Dampener pre-charge problem, cylinder imbalance, valve leakage, gas in slurry. | Check dampeners, individual cylinder pressure, valves, and feed aeration. |
| Restart pressure is abnormally high | Settled or consolidated solids, incomplete flushing, cooled or thickened slurry. | Follow blocked-line procedure; do not exceed equipment pressure ratings. |
For wear-related symptoms, review which slurry pump parts wear first and the guide to check-valve maintenance. When chemistry and abrasion occur together, diaphragm and wetted-part materials should be checked against the actual process liquid.
Send measured values across the expected operating range, not only a single design point:
The slurry pump capacity calculation guide explains how flow, solids, density, and pipeline distance connect at the first sizing stage. High-density or non-Newtonian tailings normally require laboratory rheology and a project-specific hydraulic model before final selection.
TOMINE supplies piston diaphragm and hose piston diaphragm pumps for abrasive and corrosive slurry duties. The current hydraulic reciprocating product range lists maximum values up to 800 m³/h flow, 64 MPa discharge pressure, approximately 1,000 kN plunger thrust, and 2,240 kW power. These are range limits, not one guaranteed operating point. The selected flow and pressure depend on slurry data, pump configuration, speed, materials, drive power, and system design.
Available features include double-diaphragm rupture monitoring, automatic hydraulic-oil replenishment, multi-cylinder delivery, and application-specific wetted materials. A technical proposal should also address charge-pump control, check valves, dampeners, relief protection, instrumentation, critical spares, maintenance access, and flushing.
A tailing slurry pump for material above 60% solids by weight must be selected from measured slurry behavior and the full pipeline duty. Concentration alone does not determine the pump. Rheology, maximum particle size, suction pressure, transport velocity, abrasion, pressure, shutdown time, and restart strategy are equally important.
Heavy-duty centrifugal pumps remain valid for many high-flow, moderate-head duties. Piston diaphragm and hose piston diaphragm pumps become strong candidates when high pressure, stable displacement, abrasion isolation, limited process water, and long pipeline availability dominate the decision. Send TOMINE the slurry test data and pipeline profile to compare the options on a duty-specific basis.
It means 60% of the total slurry mass is dry solids and 40% is liquid. For mineral solids with a specific gravity of 2.70 in water, 60 wt% is approximately 35.7% solids by volume and a mixture density of about 1.61 t/m³. Actual values depend on solids density and process-liquid density.
There is no automatic winner. A centrifugal slurry pump may suit a short, high-flow duty with moderate pressure and manageable rheology. A piston diaphragm or hose piston diaphragm pump should be compared when the duty combines high pressure, long distance, stable flow, abrasive wear, restricted dilution water, or serious restart risk.
Use measured rheology and particle-size data to establish the transport velocity, maintain stable feed and suction pressure, monitor density and the pipeline pressure profile, and provide controlled flushing, drainage, and restart procedures. Avoid uncontrolled low-flow operation and never force a restart above the equipment pressure ratings.
Provide flow range, dry-solids throughput, solids concentration, slurry and solids density, full particle-size distribution, maximum particle size, rheology, chemistry, temperature, suction conditions, pipeline profile, required pressure, duty cycle, power supply, flushing plan, and maximum shutdown time. These values determine pump type, size, speed, valves, materials, drive, and protection.
