Low-cost Gravity Separation

Low-cost gravity separation processing is a method used in mining and mineral processing to separate particles of different densities using gravity. This technique is particularly beneficial for its simplicity, cost-effectiveness, and minimal environmental impact. Here’s a more detailed overview of the process and its advantages:

How Gravity Separation Works

Principle: Gravity separation relies on the difference in specific gravity between the target minerals and the gangue (non-valuable) minerals. The process involves subjecting the ore to gravity forces, which results in the separation of particles based on their densities.

Methods:

1. Jigging:
   • Uses pulsating water currents to separate heavier particles from lighter ones.
   • The denser material settles faster and is collected at the bottom.
2. Shaking Tables:
   • A tilted table that uses a shaking motion to separate particles.
   • Denser particles move towards the higher end of the table, while lighter ones remain at the lower end.
3. Spirals:
   • Uses a flowing stream of water to create a spiral motion.
   • Heavier particles are pushed towards the centre and collected separately from lighter particles.
4. Dense Media Separation (DMS):
   • Uses a medium of high specific gravity in which particles are suspended.
   • Particles with higher density sink, while those with lower density float.

Advantages of Gravity Separation

1. Cost-Effectiveness:
   • Gravity separation is relatively inexpensive compared to other beneficiation processes, such as flotation or chemical separation, because it does not require expensive reagents or large amounts of energy.
2. Simplicity:
   • The process is straightforward and easy to operate, making it suitable for both large-scale industrial operations and smaller mining projects.
3. Environmental Benefits:
   • It uses water as the main medium, which can often be recycled within the system.
   • The lack of chemical reagents reduces the risk of environmental contamination.
4. Efficiency:
   • Particularly effective for coarse particle sizes and heavy minerals.
   • Can achieve high recovery rates for specific types of minerals.

Application for Sandy Mitchell Project

For the Sandy Mitchell project, the use of gravity separation is highly advantageous due to the nature of the placer deposit. The deposit is composed of sands containing rare earth elements in minerals like monazite and xenotime, which have significantly higher densities compared to the surrounding sand particles.

By applying gravity separation, Ark Mines can:

• Efficiently concentrate the rare earth elements on-site.
• Minimise processing costs by avoiding the need for complex chemical processes.
• Reduce environmental impact, making the operation more sustainable.

This approach aligns with the company’s strategy to establish a low-cost and environmentally friendly processing operation, which is crucial for the economic viability and regulatory compliance of the project​