Heavy-duty Sand Slurry Transfer Pump

What is a horizontal slurry pump?

Slurries are fluids which are a combination of liquid and solids which have varying viscosities and can be very abrasive.

A horizontal slurry pump is a horizontal pump designed to move this mixture horizontally along a pipeline. These pumps are made from durable, wear-resistant materials to stand up to continuous contact with solids which are often moving quickly.

At the heart of each pump is a powerful impeller designed to produce a strong and turbulent flow to drive the solids and prevent clogging. Each unit also has advanced hydraulics to comfortably handle slurries which can be abrasive and corrosive.

Horizontal slurry pumps are built to be efficient, reliable and durable. They are usually larger and more powerful and can generate higher flow rates than vertical slurry pumps.

What are they used for?

These heavy-duty process pumps can be used to pump a range of products, from water carrying suspended sand or gravel, to lime, ash or tailings as well as waste animal products. These types of pumps are ideal for a variety of applications in a range of different sectors:

• Metal processing  – moving abrasive slurries

• Pulp and paper – pumping black liquor in the pulp and paper industry

• Mining – transporting ore, tailings and other mining by-products

• Dredging – removing sediment and gravel from bodies of water

• Wastewater treatment – pumping wastewater during the process

The particular abrasive slurry transfer pump required by our client was needed to pump water with 50% sand content. This is known as sand slurry.

What is sand slurry and how is it used?

Sand slurry primarily consists of sand and water, but it can also include cement or fly ash to help firm up the mixture and dissipate the large amount of water in the mix.

Sand slurry is widely used in construction, mining and many industrial applications for:

• Repairing roads

It can be used to repair poor subsurface conditions and holes in the road

• Filling voids

Sand slurry can fill large voids and tanks left behind by excavation

• Stabilising subsurface conditions

It can stabilise storm water structures and any sinkhole-related road collapses

• Preserving pavement

It is a good aggregate for micro-surfacing to prolong the usable life of asphalt roads and paths

• Creating concrete

Why sand is graded in a quarry

Before sand can be added to water to make sand slurry, the sand will need to be graded in a quarry.

After rocks have been crushed, this is the process of separating the sand particles into different size categories. This is simply done by using heavy-duty sieves to sort the sand into different grades.

These various grades of sand are suitable for different construction applications, such as concrete, mortar or for plastering, depending on the required particle size and texture:

• Coarse sand – larger particles ideal for paving bases or drainage layers

• Medium sand - moderate particles generally used for concrete mixes

• Fine sand – the smallest size well suited to plastering and fine finishing work

In short, grading classifies sand based on its particle size to provide a consistent quality material for a range of specific uses. 

So what’s the best sand for sand slurry?

The optimum type of sand for sand slurry is probably a well-graded, washed silica sand with a regular particle size.

This combination gives the right balance of flowability and stability when it is mixed with water. This will produce a sand slurry with good consistency plus minimal settling or separation.

In addition, a high silica content is also important as it gives the sand slurry better bonding properties.

In terms of particle size, a well-graded medium sand is the best option, as coarse sand might not mix well or settle quickly, and very fine sand can make the slurry too liquid-y and difficult to work with.

How is sand slurry transported?

Sand slurry can be moved long distances using a heavy-duty horizontal slurry transfer pump. To do this, it employs the use of specialist hard wearing materials and a seal flushing arrangement to ensure the pump operates for long periods without downtime.

The casing was built in a ductile iron grade ensuring a specific tensile strength to protect it from impact and abrasion, which was protected by a natural rubber liner. The impeller was also lined with rubber protecting it from high velocity abrasion. The shaft was built in hardened AISI420 Stainless Steel further protecting the pump from wear.

The pump was fitted with an expeller seal which is a Sealing system cooled by the pumped liquid or an external cooling fluid. The expeller seal creates a hydrodynamic seal by creating an area of low pressure around the shaft. Expeller seals improve shaft sleeve lifetime and minimises water use. This combination ensures at low rpms and when the pump is stopped that the unit does not leak.

The specific type of pump and pump technology required depends on the flow and pressure needed to move the slurry.

For example, the slower an abrasive sand slurry is being moved, the less abrasive wear will take place in the pump itself, the pipework and related systems. So if a low flow is needed, a peristaltic or progressing cavity pump would be the better options.

Conversely, if a high flow is required, a rubber-lined centrifugal pump would be specified. That’s because the rubber-lined pump would protect the casing from wear. It would also absorb the hits from any solids which are travelling fast enough to damage non-protected parts.

What did we specify for our client?

At North Ridge Pumps, we are not specialists in just one type of pump.

As the country’s biggest pump supplier with over 25 years of trading behind us, we are highly skilled at selecting any kind of pump for any kind of application.

We use our expert know-how to come up with the optimum specification for every client – not an off-the-shelf, one-size-fits-all solution. Most important of all, we pick the best pump for every job offering the most cost-effective option.

For this project brief, we specified one of our XSP Series of rubber-lined heavy-duty slurry pumps. These have been specifically designed and developed to deal with large amounts of soft and abrasive solids with fibrous particles at high flows.

Widely used in the construction, agriculture, paper and mining industries, these heavy-duty process pumps are built to handle a range of liquids from chemical and sand slurries, manure, mud, fly ash, lime, mineral and gravel products, to waste animal products at high volumes.

High sand content, high flow

For this specific requirement, the abrasive slurry transfer pump will be used for pumping water with 50% sand content at a high flow rate of over 8 litres a second.

These pumps are usually fitted with a rubber liner to protect the casing from wear, which can happen very quickly if solids are pumped at high speed. But for this particular sand and aggregate pump, we incorporated not only a rubber-coated impeller but also a rubber-coated volute. These will both reduce the speed at which the unit wears and give longer product life.

This rubber-lined slurry pump has also been designed to offer front and rear adjustment. This enables the internal clearances to be easily adjusted as the liner wears.

It is also fitted with an expeller seal combined with a packed gland. Expeller seals help to prolong shaft sleeve life and minimise the use of water, as freshwater isn’t needed to protect the seals.

This combination of an expeller seal and a packed gland ensures that at low speeds and when the sand and aggregate pump is stopped the unit doesn’t leak.

If you have a slurry transfer application or looking to handle abrasive solids at high flows, contact North Ridge Pumps now to see how we can help you.