Why Does the Grinding Stage Put Mining Pipelines Under Severe Wear?

Introduction

Grinding is one of the most abrasive stages in mineral processing.

After crushing, ore is fed into grinding equipment such as ball mills or SAG mills, where the ore is reduced to the particle size required for subsequent classification and flotation.

The grinding process produces a slurry containing water and mineral particles. Depending on the ore and grinding circuit, the slurry can contain hard and angular particles that continuously interact with the pipeline's internal surface.

For the pipeline, the problem is not simply transporting water.

It is transporting abrasive solids in continuous motion.

This is where pipe material selection becomes critical.

1. What Happens to the Pipeline After Grinding?

A simplified grinding circuit can be described as:

Crushing → Grinding → Slurry → Classification → Flotation

After grinding, the ore is mixed with water to form slurry.

The slurry may then be transported by pumps through:

Grinding discharge lines

Sump discharge lines

Hydrocyclone feed lines

Classification circuits

Recycle lines

Flotation feed pipelines

These pipelines can operate continuously, exposing the inner pipe wall to repeated particlecontact.

图 1

2. Why Is Grinding Slurry Highly Abrasive?

The severity of pipeline wear depends on the actual slurry characteristics.

Several factors are particularly important.

Particle Hardness

Minerals such as quartz and other hard gangue minerals can cause significant abrasion.

Particle Shape

Angular particles generally create more aggressive contact with the pipe wall than rounded particles.

Particle Size

Larger particles can produce stronger impact, especially where flow direction changes.

Solids Concentration

A higher concentration means more solid particles passing through the pipe over the same period.

Flow Velocity

Increasing velocity can increase the frequency and intensity of particle-wall interaction.

Therefore:

Hard particles + high solids concentration + high velocity = demanding pipeline wear conditions.

3. Where Does the Most Wear Occur?

The straight pipe is not necessarily the most critical location.

Straight Sections

Continuous sliding of particles along the internal wall gradually removes material.

Elbows

When the slurry changes direction, particles can impact the elbow wall.

The outer radius of an elbow can become a high-wear area.

Reducers

Changes in cross-sectional area can alter flow conditions and create localized turbulence.

Pump Discharge

Higher flow velocity and pressure fluctuations can increase the mechanical demands on downstream pipeline components.

Valves and Connections

Changes in flow direction and geometry can create localized wear.

For this reason, a grinding slurry pipeline should be evaluated as a complete system rather than by looking only at straight pipe sections.

4. Why Consider UHMWPE for Grinding Slurry?

UHMWPE stands for Ultra High Molecular Weight Polyethylene.

With a molecular weight commonly above 1.5 million, UHMWPE provides a combination of abrasion resistance, impact resistance and low friction.

For grinding slurry applications, the most important characteristics are:

High Abrasion Resistance

The UHMWPE internal surface is designed to resist continuous contact with abrasive mineral particles.

This makes it suitable for slurry transportation where wear is a major maintenance concern.

Low Friction

UHMWPE has a smooth internal surface and a low coefficient of friction.

This can help reduce resistance to slurry flow and should be considered when calculating pipeline pressure loss.

Impact Resistance

Grinding circuits can contain relatively coarse particles.

UHMWPE's impact resistance helps it tolerate repeated particle contact without behaving like a brittle material.

Chemical Resistance

Mineral processing circuits can contain acidic, alkaline or salt-containing process water and reagents.

UHMWPE provides good resistance to many chemical environments.

图 2

5. UHMWPE vs Bare Steel in Grinding Slurry

Bare steel provides high mechanical strength, but the steel surface is directly exposed to abrasive particles.

With continuous slurry transportation, the inner wall can gradually become thinner.

UHMWPE changes the wear surface.

Instead of allowing the abrasive slurry to directly contact steel, the UHMWPE layer acts as the internal wear-resistant surface.

Bare Steel

Steel structure → Steel surface → Abrasive slurry

UHMWPE Lined Steel

Steel structure → UHMWPE liner → Abrasive slurry

The steel provides structural support.

The UHMWPE liner takes the abrasive contact.

This is the key reason UHMWPE lined steel pipe can be attractive for demanding grinding slurry applications.

6. What About Rubber-Lined Steel Pipe?

Rubber-lined steel is also used in mineral processing.

Rubber can provide good impact absorption and abrasion resistance under suitable conditions.

However, UHMWPE offers a different performance profile.

Actual service life depends on the slurry and operating conditions. No material should be assigned a fixed service life without application data.

7. When Should UHMWPE Lined Steel Be Considered?

For grinding slurry pipelines, pressure requirements can be just as important as abrasion resistance.

If the system requires substantial mechanical strength or higher pressure capability, a UHMWPE lined steel pipe can be considered.

The basic structure is:

Outer Steel Pipe

→ Provides structural strength

UHMWPE Inner Liner

→ Provides abrasion-resistant flow surface

This configuration is particularly relevant for:

Pump discharge pipelines

High-pressure slurry lines

Hydrocyclone feed pipelines

Concentrated grinding slurry

Long-distance abrasive slurry transportation

The actual pressure rating must be determined from the steel pipe design, liner structure, temperature, connection system and operating conditions.

图 3

8. How Should UHMWPE Pipe Be Selected for Grinding Slurry?

The pipe should not be selected based only on diameter.

At minimum, the following parameters should be evaluated:

Pipe Parameters

DN

Pressure / PN

Wall thickness

Pipe length

Connection type

Slurry Parameters

Ore type

Solid concentration

Slurry density

Particle size

Maximum particle size

Particle hardness

Particle shape

pH

Operating Parameters

Flow rate

Flow velocity

Operating pressure

Temperature

Pipeline length

Elevation difference

These parameters determine the actual mechanical and wear conditions inside the pipeline.

9. Typical UHMWPE Pipe Parameters

For mining applications, typical UHMWPE pipe specifications may include:

The final specification should be confirmed according to the actual application and applicable manufacturing standard.

10. Don't Forget the Grinding Circuit Elbows

If a grinding slurry pipeline uses UHMWPE straight pipe but conventional material elbows, the elbows may still become the maintenance bottleneck.

The reason is simple:

The slurry changes direction at the elbow.

Particle impact becomes concentrated.

Therefore, wear-resistant design should consider the complete flow path:

Straight Pipe + Elbow + Tee + Reducer + Flange + Connection

UHMWPE elbows can be used where the application requires a wear-resistant internal surface at changes in direction.

11. Can UHMWPE Handle Every Grinding Application?

Not automatically.

UHMWPE is highly wear resistant, but material selection must still be based on the actual operating conditions.

Particularly severe applications may involve:

Very coarse particle

Extremely high solids concentration

High flow velocity

High operating pressure

Large elevation differences

Severe impact at elbows

In these cases, the pipeline should be technically evaluated before selecting the pipe structure.

For higher-pressure applications, UHMWPE lined steel may be more appropriate than a standalone polymer pipe.

The objective is not simply to choose the most wear-resistant material.

The objective is to match the pipe structure to the complete grinding circuit.

12. Practical Selection Example

Suppose a copper processing plant needs a pipeline to transport grinding slurry from the grinding circuit toward classification.

The buyer provides:

DN400

High solids concentration

Abrasive mineral particles

Continuous operation

Several elbows

Significant operating pressure

The selection process should then consider:

1. Pipe diameter → DN400

2. Pressure → Determine required PN / pressure-bearing structure

3. Slurry → Evaluate particle size and concentration

4. Wear → Identify high-wear elbows and fittings

5. Structure → Compare UHMWPE pipe and UHMWPE lined steel

6. Connection → Match pipe, elbows and flanges

This is a much more reliable approach than simply ordering a DN400 pipe based on diameter.

FAQ

Why is the grinding stage so abrasive?

Grinding produces mineral slurry containing particles that can continuously slide against and impact the internal pipe wall. Particle hardness, size, concentration and flow velocity all influence the resulting wear.

Can UHMWPE pipe be used for grinding slurry?

Yes. UHMWPE can be used for abrasive mineral slurry transportation when its pressure, temperature and mechanical requirements are within the selected pipe specification.

Is UHMWPE better than steel for grinding slurry?

For internal abrasion resistance, UHMWPE can provide a significant advantage over bare steel. However, steel may provide higher structural strength, so high-pressure applications may require UHMWPE lined steel rather than standalone UHMWPE.

Why do grinding slurry elbows wear faster?

The slurry changes direction at an elbow, causing particles to impact and slide against localized areas of the elbow wall. The resulting wear can be higher than in straight pipe sections.

What information is needed to select a grinding slurry pipe?

Provide DN, operating pressure, flow rate, slurry concentration, slurry density, particle size, maximum particle size, pipeline length and number of elbows.

Conclusion

The grinding stage creates one of the most demanding environments for mineral-processing pipelines.

The combination of hard mineral particles, continuous flow, solids concentration and changes in flow direction can create severe internal abrasion.

UHMWPE provides a smooth, wear-resistant internal surface that can be considered for grinding slurry transportation.

Where higher structural strength and pressure resistance are required, UHMWPE lined steel pipe combines a steel pressure-bearing structure with a UHMWPE wear-resistant liner.

The most important point is:

Do not select a grinding slurry pipeline by DN alone.

Evaluate the slurry + pressure + velocity + particle size + pipeline geometry before selecting the pipe.

Request a UHMWPE Pipe Quotation

For UHMWPE mining pipe, UHMWPE lined steel pipe, UHMWPE elbows and link flanges, send us:

DN + PN + Slurry Type + Solid Concentration + Particle Size + Flow Rate + Pipeline Length + Quantity

Luoyang Zhengju New Materials Technology Co., Ltd.

WhatsApp：+86 19937270645

Email: baibaili456@gmail.com

Wechat: +86 19937270645

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