In a Valve magazine article, Challenges of Medium Density Slurry Service in Mining and Mineral Processing, Emerson’s Mike Gordon describes innovations in knife gate valve technology to address these slurries.
Mike opens defining medium density slurries:
…applications where solids sized between 5 to 1,000 microns are present in the fluid medium and percent solids range from 5 to 20% by weight…
Traditional valve choices were between:
…an economic light-service valve that, in medium-slurry applications, will require frequent replacement, or a heavy-duty valve that is over-specified and expensive.
The design for an isolation knife gate valve for medium-slurry applications, found in coal, gold, silver, copper, uranium mining, and more, has:
…a higher thrust requirement due to the friction that occurs because of the gate sliding on the internal urethane during opening and closing cycles. If not designed correctly, gates will tend to deflect and potentially damage the liner on the downstream side along the bottom edge as pressure on the gate increases when the valve is nearing closed position… will not trade-off isolation, thrust and liner life in accounting for gate deflection.
Mike highlighted the innovation of:
…a two-piece body construction and field-replaceable snap-in liner design that represents a new type of knife gate valve. No special tools or highly trained personnel are needed to replace the liner. An integral seat-face seal eliminates the need for flange gaskets, reducing installation costs and making installation easier.
He shares a case study of a global coal producer in an Australian coal preparation plant, where:
…stainless cyclone feed knife gate valves were being destroyed prematurely by abrasive coal fines and were failing in less than 12 months.
Read the article for how this isolation knife gate valve for medium slurries reduced maintenance costs and improved overall performance for the production process. Visit the medium-slurry processing case study on this Australian mine as well.