An analytical approach to explain complex flow in spiral concentrator and development of flow equations

A spiral concentrator is a density separation equipment used to beneficiate coal and various minerals such as iron ore, chromite ore, gold, beach sand minerals, etc. The flow pattern developed in the equipment is complex and unique, yet the operation is straightforward with low capital and operating expenditure. Spirals are applied for beneficiation of material in a size range that is finer than 2 mm and can recover heavy minerals as fine as 0.01 mm. The understanding of the unique flow pattern has kept researchers engaged over the last few decades. With a clear understanding, it could be controlled and modified to improve the operating efficiency, Ep (Ecart Probable Error also known as a probable error in separation) and acceptability of spiral concentrators for processing of fines and slimes, currently being discarded and dumped in the tailing ponds. An attempt has been made in the present paper to explain the generation of complex flow patterns using classical solid mechanics in the fluid and slurry system. The findings could describe the selective separation of particles in different zones in a cross-section considered on the spiral trough. The paper also discusses the application of the force balance model to explain the generation of secondary circulation. Due to laminar and turbulent flow regimes in the spiral concentrator, various equations have been proposed in the literature, consisting of different equations for different zones. An attempt has been made to present a unified flow equation to calculate flow velocity to varying positions on the spiral trough.

Automated summary

Spiral concentrators are efficient density separation equipment used for beneficiation of various minerals. They have a unique and complex flow pattern, but their operation is straightforward with low costs. Understanding the flow pattern can help improve operational efficiency and recovery of heavy minerals.