The right wet-end material depends on what the slurry does inside the pump. High chrome white iron is often considered where coarse or sharp solids make cutting and impact a concern. Rubber can perform well with finer solids when its flexibility helps absorb particle contact. Polyurethane may suit certain fine-particle duties involving sliding abrasion, but its suitability depends on the particular formulation and the slurry chemistry.

These are starting points, not interchangeable rules. A small amount of oversize material can change a decision based on average particle size. Temperature, pH, reagents, pump speed and the wear observed on existing parts also matter. This guide provides a practical way to compare the three materials before specifying an impeller, liner, volute or throat bush.

First, identify the wear problem

An impeller and a liner in the same pump do not necessarily experience the same contact with solids. Particles can strike the impeller inlet and vane leading edges, slide along flow passages, and concentrate wear in particular casing or liner areas. Operating away from the pump’s intended duty can also change wear patterns. A material that survives one part of the wet end may therefore be a poor choice for another. metso.com

Before comparing materials, inspect the removed parts:

• Deep cuts, gouges or torn edges suggest sharp particles, oversize solids or impact may be important.
• Fairly even surface loss points toward sustained abrasive contact, though inspection alone cannot identify every cause.
• Localized rapid wear calls for a check of the operating point, internal clearances and flow path as well as material choice.
• Swelling, softening, cracking or unusual surface attack calls for a review of chemical and temperature compatibility.

Record where damage occurs and how quickly each component reaches its replacement limit. Changing material without investigating an unusual wear pattern may leave the underlying operating problem in place.

High chrome, rubber and polyurethane: a decision table

The table is a screening guide, not a guarantee of service life. Confirm the actual grade, component design and limits with the parts supplier.

Published pump guidance identifies particle size and properties, temperature, chemistry and impeller speed as material-selection inputs. It also describes hard metal as generally more tolerant of coarse material, while rubber and polyurethane have applications among finer-particle duties. Those generalizations do not establish limits for an unspecified supplier grade. metso.com

When high chrome is the stronger starting point

High chrome is a family of abrasion-resistant white cast irons, not a single universal recipe. ASTM A532/A532M covers abrasion-resistant cast irons used in industries including mining and milling; the specified class, composition and condition still need to be identified when ordering parts. store.astm.org

Consider high chrome when the feed includes coarse or angular particles, occasional oversize solids, or cutting damage that an elastomeric part cannot tolerate. It is particularly important to know the maximum credible particle size, not merely the median size reported in a slurry sample. A screen failure, process upset or changing ore feed can expose the pump to material absent from a representative average.

Hardness alone does not settle the choice. The alloy must suit the slurry chemistry, the pump’s construction and the required component geometry. Nor should an existing rubber-lined assembly be assumed to accept a metal liner or impeller without a fit and configuration review. Specify the complete pump model and part identification before requesting an alternative.

When rubber deserves consideration

Rubber wear parts are often considered for finer solids and duties where an elastic surface can absorb particle contact. Their performance depends on the rubber compound, particle shape, temperature and chemical environment. A rubber liner that performs well in one fine tailings stream may suffer cuts in another stream containing a small fraction of sharp or oversize particles.

“Rubber” is not one material specification. Natural and synthetic compounds can differ substantially in chemical resistance and service temperature. Ask which compound is offered for the actual slurry rather than accepting a generic “rubber-lined” description. Published technical guidance also cautions that oversize scrap and sharp particles can damage elastomer wear parts, especially an impeller. metso.com

If an existing rubber component has failed early, preserve photos of the worn surface and report whether it was cut, torn, swollen or worn down gradually. Those observations are more useful for the next material decision than replacement interval alone.

When polyurethane may be worth evaluating

Polyurethane is another material family with multiple formulations. Some grades are used where fine particles create sliding or low-angle wear, and certain formulations may be considered when cutting of a rubber part is a concern. These statements describe possible applications; they do not establish that polyurethane will outlast rubber or metal in a particular pump.

The formulation matters. Technical guidance distinguishes different polyurethane types and warns against treating them as identical. Its published particle-size and temperature observations refer to the materials discussed in that handbook; they should not be copied as performance specifications for parts from another supplier. Chemical exposure, especially process reagents, requires a grade-specific check. metso.com

For a proposed polyurethane slurry pump parts configuration, request the exact compound identification, compatible pump model, intended component and documented chemical and temperature limits. If the supplier cannot confirm those details, the material comparison remains incomplete.

Five checks before specifying a replacement material

1. Describe the full solids range

Request particle-size distribution and maximum observed or credible size. Add particle shape, hardness where known, and the likelihood of foreign objects or intermittent coarse feed. Maximum size can have a different effect on a soft liner than the average size suggests.

2. Separate density from solids concentration

Slurry specific gravity describes the mixture’s density relative to water. Solids concentration describes how much solid is present, commonly reported by mass or volume. Both are useful, but neither replaces particle-size information. State the basis of any concentration figure so the supplier does not mistake a mass percentage for a volume percentage.

3. Report chemistry and temperature together

Provide measured pH, liquid composition, known chlorides or process reagents, and normal and maximum temperatures. Chemical compatibility depends on the specific metal alloy or elastomer formulation and exposure conditions. Do not choose polyurethane, rubber or high chrome from a pH value alone.

4. Check the component and pump configuration

An impeller, throat bush and casing liner can have different wear exposure and mounting requirements. Supply the existing pump model, serial number if available, part number, drawings or dimensions, and photographs of the removed part. Confirm whether a proposed material change requires a different component design or matching parts.

5. Compare operating cost using actual records

Record part cost, operating hours to a defined replacement condition, labor, downtime and any resulting loss of pump performance. A lower purchase price can be expensive if replacements interrupt a critical process; a more expensive part also needs evidence before its extra cost can be justified.

For a broader inventory of components and available configurations, review slurry pump parts. If the current problem is premature wear rather than an initial material decision, the guide Why Does a Heavy Duty Slurry Pump Wear So Fast? provides a useful starting point for diagnosing the cause.

Illustrative example: a mineral-processing transfer pump

Illustrative example only; these figures do not describe an actual installation or a product rating.

A plant requests replacement wet-end parts for a pump transferring mineral slurry at 120 m³/h, 32 m required head, slurry SG 1.30, 25% solids by mass, and pH 7.5. Most measured particles are fine, but the plant occasionally finds 8 mm angular fragments after a screen upset. The liquid normally runs at 35°C.

The fine portion alone could make a rubber or polyurethane option worth examining. The intermittent angular fragments, however, may cut or damage an elastomeric component. High chrome should therefore be assessed alongside the soft-material options. The team should first establish how often oversize reaches the pump, inspect the existing parts for cuts or impact damage, and verify the pump configuration. It should also identify any flotation or cleaning chemicals omitted from the initial pH reading.

The flow and head figures are necessary for checking the pump duty; they do not independently identify the best wear material. No service-life ranking can be calculated from this short description. The useful outcome is a shortlist and a precise request for grade-specific compatibility and fit information.

What to send when requesting a material recommendation

A useful inquiry allows the supplier to check both material and component compatibility. Send:

1. Pump model and identification of the part to be replaced.
2. Required flow, head and normal operating range.
3. Slurry SG and solids concentration, with the concentration basis stated.
4. Particle-size distribution, maximum size, shape and any intermittent oversize.
5. pH, relevant chemicals or reagents, and normal and maximum temperature.
6. Current material, service interval and photos of worn parts.
7. Part number, drawings or key dimensions if ordering a replacement component.

If these data are incomplete, identify what is measured and what is estimated. That is more useful than presenting an uncertain maximum particle size as a confirmed limit.

FAQ

Can polyurethane replace a rubber slurry pump liner directly?

👉Do not assume a direct substitution. Confirm the pump model, liner geometry, mounting arrangement, mating components and the proposed polyurethane grade. Chemical and temperature suitability also need checking.

Is high chrome always better for abrasive slurry?

👉No. Abrasion involves different particle sizes and contact patterns. High chrome is often considered for coarse or cutting duties, while a suitable elastomer can be competitive in certain fine-particle duties. Compare the actual slurry and observed wear.

Which material is suitable for fine tailings?

👉Rubber and some polyurethane formulations may be candidates; high chrome may also be evaluated. Particle shape, occasional oversize, reagents, temperature and pump operation determine which candidates remain viable.

Does a higher slurry SG mean the pump needs high chrome parts?

👉Not by itself. Slurry SG helps describe the duty, but particle size and shape, concentration, chemistry, operating point and wear pattern are also needed for material selection.

What should I check if a new liner wears out quickly?

👉Document the damage location and appearance, then check oversize solids, chemistry, pump operating conditions and component fit. A short life does not prove that the material family alone was wrong.

Can the impeller and liner use different materials?

👉Some pump configurations can use a combination of hard-metal and elastomeric wet-end components. Availability and suitability depend on the specific pump design and matching parts; confirm the complete configuration before ordering. metso.com

CTA

Need to select replacement wet-end parts? Send the pump model, required flow and head, slurry SG, solids concentration, maximum particle size, pH, temperature, application and photos of the worn components. These details make it possible to review material suitability and component fit before a quotation.

Technical references for the article

• ASTM A532/A532M — Standard Specification for Abrasion-Resistant Cast Irons. Supports the description of abrasion-resistant cast-iron specifications; it does not certify any unspecified part. store.astm.org
• Slurry Pump Basic Handbook — wear protection and material selection chapters. Used for wear locations, selection inputs and general distinctions among hard metal, rubber and polyurethane. Its grade-specific limits have deliberately not been applied to the products on this site.