Cassiterite is concentrated by: (a) Hand picking (b) Levigation (c) Electromagnetic separation (d) Wilfley table method

Levigation, also known as hydraulic washing, is a method of ore concentration where the heavier ore particles are separated from lighter impurities based on their differential settling rates in water. This simple yet effective process involves washing the ore with a current of water.

During levigation, the mixture of different particles is stirred or agitated with water. The lighter particles, being less dense, float on the surface and are washed away, whereas the denser ore particles like cassiterite settle to the bottom.

In practice, the process may be carried out in fixtures like sluices or settling tanks. Improvements in levigation include optimizing the flow rate to better distinguish between particles of different weights and using a series of tanks for increased efficiency.

Gravity separation is a mineral processing method for separating ore particles based on their specific gravity or density differences in a medium, typically air or water. This method effectively separates heavy minerals from lighter gangue or surrounding rock without the use of chemicals, making it a more environmentally friendly and cost-effective method.

Ores like cassiterite, being denser, can be efficiently concentrated using gravity separation techniques. The equipment used can vary from simple sluices to sophisticated machinery like jigs, spirals, or shaking tables.

Improvements in gravity separation techniques involve fine-tuning parameters such as the medium's density, particle size distribution, and flow dynamics, enhancing the separation accuracy and reducing product loss.

Ore concentration is a fundamental step in the metallurgical process that increases the percentage of the desired metal within its ore by removing non-valuable minerals or gangue. The chosen method of concentration depends largely on the ore’s properties like size, shape, density, magnetic properties, and chemical stability.

Several techniques can be employed to achieve ore concentration, including froth flotation for sulfide ores, magnetic separation for magnetic ores, and gravity separation for dense ores like cassiterite.

Improving ore concentration techniques involves enhancing recovery rates and minimizing energy and water usage. It also includes development of more selective reagents for flotation processes, or integrating various concentration methods for more effective results.

The Wilfley Table method is a refined form of gravity separation utilizing a mechanical shaking action that enhances the segregation of ore particles on a table. This method separates particles based on their density and size, which is especially useful for ores such as cassiterite, which are denser and coarser.

As the table shakes, the lateral water flow and shaking motion cause the denser particles to crawl along the table's surface to the higher side, while the lighter particles move to the lower side, eventually separating the desired ore.

Refinements to the Wilfley Table method might include precise control of the water flow, adjustment of the shaking mechanism, and optimization of table inclination to improve the efficiency and purity of the concentration process.