Maximizing efficiency with severe service control valves

Coarse Particle Flotation (CPF) is a process designed to increase mineral recovery by efficiently capturing the large particles that are typically lost during traditional flotation. By recovering these coarse particles, CPF enhances flotation efficiency by approximately 2 to 5%, significantly reducing the loss of valuable minerals in tailings.
Additionally, CPF provides cost and energy savings by minimizing the fine grinding usually needed for traditional flotation. As grinding is among the most energy-intensive processes, reducing this requirement considerably lowers operational costs. CPF has also emerged as a critical innovation in improving tailings management, enhancing water recovery, and supporting land reclamation efforts.

challenges with
coarse particle flotation

A critical component for achieving maximum mineral recovery in CPF systems is the control valve at the bottom of the flotation tanks. These valves must possess exceptional throttling response, optimal flow dynamics, reliability, and wear resistance. A specialized engineering approach is essential to designing valves robust enough to withstand the abrasive conditions inherent in flotation operations.
The primary challenge in valve design for CPF systems is accounting for variations in slurry behavior between start-up conditions and normal operation.
Changes in slurry properties significantly impact valve sizing and throttling performance. Without proper engineering, these fluctuations can cause valve and piping failures, leading to unplanned downtime and costly repairs. Therefore, severe service control valves for abrasive tailings applications require comprehensive engineering assessments and design considerations to ensure dependable operation.

SAF's Design Approach for Severe Service Control Valves

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Dedicated engineering effort to accurately size each valve for the full range of operational conditions.
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Optimizing flow components to reduce turbulence throughout the majority of valve throttling positions.
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Selecting the toughest available materials for flow components to mitigate erosion damage.

Designing for High Viscosity Fluids

In CPF applications, it is critical to evaluate typical operational scenarios, including minimum, normal, and maximum flow conditions. Additionally, understanding start-up flow conditions is essential, as these differ significantly from regular operational states and can drastically influence valve throttling characteristics. During start-up, tailings exhibit very high viscosity and non-Newtonian fluid behavior, necessitating specialized Cv (flow coefficient) correction methods tailored for high-viscosity fluids.
Valve sizing for non-Newtonian fluids involves complexities that defy straightforward calculations. Instead, iterative approaches combined with empirical data assist engineers in verifying that valve designs adequately handle high flow demands associated with viscous tailings fluids. Comprehensive flow analysis and precise valve sizing represent essential initial steps in custom-engineering control valves for CPF.
The next step involves designing and developing valve trim components that directly regulate fluid flow. Computational Fluid Dynamics (CFD) simulations are utilized iteratively to analyze velocity gradients, turbulence, eddies, and recirculation zones at varying flow conditions. These simulations identify and mitigate potential erosion points, improving valve reliability and longevity.

Material Selection

The final step in the design process is selecting materials that are appropriate for the given application in terms of corrosion, temperature, pressure limitations, and especially abrasion. In some cases, a proprietary composition of carbide is used to balance toughness and strength with abrasion resistance, as these valves must function in some of the harshest flow environments, with large solids and high-velocity tailings fluids.
SlurryFlo Control Valve with Flat Bottom Gate Design and custom Orifice
SAF’s engineering philosophy, exemplified in the development of SlurryFlo valves, demonstrates practical and reliable severe service valve performance in tailings discharge applications.
Mining operators have historically avoided using control valves in abrasive tailings environments due to performance concerns. However, specially engineered severe service control valves are designed for these conditions. They provide precise control, reduce turbulence, and ensure centered flow, leading to greater reliability and efficiency.
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