Mechanical seals and support system specialist AESSEAL is upgrading 14 pumps for a mining company based in Namibia. The upgrade will include installing AESSEAL’s CDPH heavy-duty double slurry mechanical seals, SW2 water management system and fluid distribution unit (FDU) for the pumps in a phased approach over the next six to 12 months.

AESSEAL has already upgraded seven pumps and will upgrade the remaining pumps over the next six to 12 months.

The mining company chose to upgrade 14 pumps to resolve the challenges it encountered with its current pump system. The mine had to deal with persistently low pressure in the gland service water system, which caused excessive wear on the shaft sleeves. As a result, the sleeves had to be changed two or three times a month, which required the slurry pump to be taken offline, isolated and stripped to replace the shaft sleeve and gland packing.

Seal Suited to Arduous Conditions

AESSEAL’s CDPH heavy-duty double slurry seal was specifically designed to meet the arduous requirements of slurry pumping applications such as tailings and thickener underflow applications.

With the large ports and increased radial clearances, coupled with the correct sealing plan, the mechanical seal is able to maintain a stable fluid film between the faces to ensure extended seal face life.

The stationary faces are oversized to allow for more radial movement, and the metal parts are heavy duty. Specialised corrosion- or erosion-resistant metal parts are also available.

Other design features include inboard reverse seal face balance, no flush or port connection, and hydraulically balanced seal faces.

AESSEAL marketing manager Jana Britz says the upgrade provides endless customer benefits which include reduction of maintenance costs associated with the repacking of pumps, which in turn, removes the need for constant external seal service water.

Traditional sealing solutions require a continuous supply of clean water to flush the gland packing.

For example, a large gland packed slurry pump can require up to 180 ℓ/min – equating to more than 90-million litres a year per pump – in addition to a significant amount of energy to drive the extra pump required to convey this supply of water.

An AESSEAL dual seal and seal support system will use less than 38 ℓ of water a year.

Britz explains that the key to reducing water consumption and having a reliable sealing solution is to use a dual, double balanced mechanical slurry seal with a seal support system. The seal support system is designed to ensure that the seal faces are lubricated with a clean, cool fluid at a higher pressure than that in the pump stuffing box.

Following this approach ensures that most process upsets, such as operating the pump away from its best efficiency point, cavitation and loss of pumped fluids are addressed.

SW2 Water Management System

AESSEAL’s SW2 water management system can save 6.3-million litres of water per pump a year. The SW2 system is piped as an API Plan 53A – a self-regulating system that can refill and repressurise itself in any “mechanical seal upset condition”.

In line with the company’s policy of providing a full back-up service, AESSEAL engineers have been on site every week to monitor the new system and provide advice and support for the client.

While on site, they check for pump operational issues – such as cavitation, running the pump against a closed valve, pump misalignment and running the pump dry – which could adversely affect the mechanical seal. The team also checks the functioning of the FDU system.

The team identifies problem areas with pumping slurry, discusses and reports on problematic pump curves and offers solutions to the challenges together with the other teams on site.

AESSEAL also assists with the site’s planned maintenance programmes to ensure stock availability.

The weekly site visit is an indefinite service for as long as AESSEAL’s equipment remains on site, which benefits customers because downtime is mitigated and costs, such as water, are lower, says Britz.

The company aims to continue providing solutions that meet the production expectations of companies while supporting customers and developing products that benefit the environment.

“Technology, together with a net-zero approach, is without a doubt, progressively becoming an important cornerstone for corporates to display their leading edge and commitment to the environment,” says Britz.

AESSEAL has reinvested more than 7% of yearly sales revenue in research and development over the past decades, which has led to an advanced range of sealing technology available globally.

The technological developments supporting the water savings have “proven to save millions of litres of water” per pump a year, she concludes.