Enhancing slurry pump reliability

By installing the new Gland Guard, users can reduce flush flows in slurry pumps by an average of 70% and reduce overall plant water usage. Sidney Komape, Senior Applications Engineer – Pumps, elaborates. 

The world is becoming increasingly aware of the challenges regarding our scarce water resources and the benefits of saving or, rather, not wasting, water. This is becoming a major factor in the approval of projects. 

Slurry pumps are major consumers of water on a plant and the different suppliers of slurry pumps are constantly working on technology to reduce water usage. One of the main areas where consumption of water occurs outside of the wet processing system in slurry pumps, is at the gland seal.

There are three types of sealing arrangements in slurry pumping: 

1. Expeller Seals:  The expeller operates like a secondary impeller at the back of the impeller and “expels” the media away from the bearings by virtue of the expulsion vanes, thus eliminating the need for water for sealing. The expeller is, however, limited in terms of application as it depends on the pump speed for effectiveness, and this may further be limited by inlet conditions.
2. Mechanical Seals:  Mechanical seals don’t use a lot of water, and in some cases no water at all, to seal the pump (however, this is provided that certain operating criteria are met, and this is generally not always the case in the mineral processing environment). The biggest drawback is their price and reliability in slurry pumps.
3. Stuffing Box Seal: This sealing arrangement is widely used and uses external water (GSW- Gland Sealing Water) to seal. Properly administered and maintained, they are very effective in sealing all applications, e.g. mill discharge pumps, multistage pumps, etc.

On medium-sized pumps, for example the 6/4 to 8/6 range, the pumps can consume around 1.26 l/s which can amount to a significant quantity of water over time. Last year, Multotec's pumps division looked at upgrading our pump range and technology. With the nominated technological partner in Australia, 7D, several aspects of our pump were considered for upgrades that would significantly improve our pump.

One of the improvements was on the GSW sealing arrangement (because GSW is widely used and effective).

7D has designed and patented Gland Guard, which addresses two key efficiency issues:
•    high flush flow, and
•    solids entering the gland packing.

These two problems may result in safety issues; reduced bearing life; reduced life of sealing arrangement componentry; huge product dilution and increased water usage, all of which impact adversely on the total ownership costs of any operation.

Benefits of the Gland Guard:

• Gland Guard reduces flush flows by an average of 70% whilst attaining longer sleeve, packing and lantern restrictor life. The reduction in water usage is significant as this will be in line with that of mechanical seal water usage.
• An extremely hard (1300 Vickers) Wolfram™ replaceable bush, engineered to minimise flush flow
• A specialist lip seal, which keeps slurry out of your gland packing even during shuts and enables gland flush to be turned off & on standby pumps
• This combination significantly reduces operational costs.

Without re-inventing the wheel (the mere thought of which would be daunting in the slurry pump game), a seemingly minor modification can result in improvements which would directly have a significant positive impact on our product and its ownership. These benefits cascade into our customers’ operations, resulting in a win-win situation in our valued partnerships.