Dart valves

Accurate and reliable level control is critical for efficient flotation operations. In large flotation cells, even a minute of lost concentrate mass pull can result in significant financial losses. Changing process conditions and low availability often drive the need for enhanced level control solutions.

The improved dart valve level control system is designed for high performance, maximum availability, and low operating costs. These dart valves are ideal for Metso TankCell, OK-cell, and similar flotation machines, as well as shut-off applications in sump tanks.

Accurate and responsive control

Smooth froth flow rate is one of the key factors affecting froth recovery and has a positive influence on overall metallurgical performance. Accurate and responsive level control is vital to ensure this. Properly sized steep-angle plugs need to be matched with a long-stroke actuator. The length of the stroke is a key element contributing to accurate level control. Furthermore, with correct sizing, the response to the control input is practically linear.

Improved actuator design

The new actuator unit precisely measures the valve position using intelligent piston positioners. In the previous design, the position was mechanically measured from the outside, making it more susceptible to structural damage.

Wear life 

The key design criteria is to maximize the wear life of the level control components. The Inside Dart with open design has proven to offer the longest wear life of all known dart valve arrangements. An open tank area around the inlet and a wide intermediate channel after the socket are essential. They guarantee the lowest possible flow rates from cell to cell without the risk of sanding. Laminar flow and moderate velocity are the key factors contributing to long wear life.  A properly selected range of stroke is another important factor determining wear. If the stroke in typical conditions is too short, i.e. the valve operates near the closed position, the flow rate will be high, thus inducing wear.

Upgrade scope

The scope can be customized to meet the specific requirements of the application.