Limestone Quarry Achieves Major Savings by Replacing Rotary Airlocks with Trickle Valves
Wagner Quarries Company is a state-of-the-art limestone mining facility in Sandusky, OH. Founded in 1912, the facility produces approximately three million tons of limestone products per year. Large baghouse dust collectors are used on-site to capture massive amounts of airborne dust derived from the blasting, drilling, crushing, loading, and hauling operations required to extract this valuable resource.
The (Expensive) Problem: In 2010, maintenance foreman Paul Schaffer decided to look for a better alternative to the problematic rotary airlock valves used to empty the mine’s dust collectors. The highly abrasive limestone dust made short work of expensive rotary valves, and their cumbersome drive assemblies were difficult to access for repairs and maintenance.
Shaffer ultimately contacted Aerodyne, and an engineering representative visited the quarry to analyze the situation and offer recommendations. Once onsite, he learned about the quarry’s winter shutdown, which left rotary airlock valves unused for several months at a time: the valves would inevitably rust and jam up during this period, making costly repair or replacement of the valves necessary when production resumed.
The Solution and Measurable Results: Based on the product manager’s recommendations, Mr. Schaffer made the decision to replace Wagner Quarry’s problematic rotary airlock valves with low-cost trickle valves from Aerodyne: trickle valves are designed to easily handle abrasive limestone dust at a fraction of the cost of the older rotary airlock valves. Because the trickle valve has no moving parts and requires no controls, lubrication, or power supply, it would not be affected by the seasonal shutdowns.
Negative pressure in the dust collector holds the duck-bill sleeve of the trickle valve closed, creating a tight airlock seal. As a head of material builds up above the valve, the weight forces the sleeve open, allowing the dust to discharge continuously until the system’s negative pressure automatically re-closes the valve.
Extra Savings: Schaffer estimates savings between “$8,000 and $10,000 a year or more” with the installation of the trickle valves. There are major savings on the initial cost of the valves for the facility, but he says they also “[free] up maintenance personnel to work on other equipment,” which is huge.
The installation of the trickle valves clearly saved the quarry money on maintenance, but they also improved overall process efficiency. The tight airlock seal of the trickle valve is far superior to that of a rotary airlock valve—which tend to progressively leak more and more air as they wear out. A leaking airlock valve causes air intrusion, which harms the efficiency of the entire dust collection system. Because the trickle valve requires no tools to service, a strong, consistent airlock seal can be maintained with minimal effort.
