Sealing the point where the shaft passes through the pump casing is one of the oldest slurry-pump design problems. Three approaches dominate, and the right choice depends on the duty and on how much clean water the site can spare.
Gland packing with flush water
The traditional option. Packing rings are compressed around the shaft and a small clean-water feed keeps slurry out. It is simple and forgiving, but it uses a steady stream of seal water — which dilutes the product on concentrate duties and costs water on dry sites.
Expeller (centrifugal) seal
An expeller throws slurry away from the gland using centrifugal force, cutting or eliminating the flush water on many duties. It works best near the design point; at very low flow the sealing force drops, so it is not universal. We use expeller arrangements where reducing seal water matters, such as concentrate transfer.
Mechanical seal
A mechanical seal gives the cleanest shaft sealing and the least leakage, at a higher first cost and more sensitive installation. It suits duties where leakage is unacceptable or where packing simply will not hold.
How we decide
For most abrasive mining duties we start from gland packing or an expeller arrangement for serviceability, and move to a mechanical seal only where the process demands it. The seal decision is made together with the liner material and the duty point, not in isolation.
