Leaching of uranium ore and gold ore is done in

ANS:B - Pachuka tanks

Pachuca tanks, also known as Pachuca agitated tanks or Pachuca mixers, are a type of tank commonly used in hydrometallurgical processes such as leaching. They are specifically designed to facilitate the mixing of solid particles, typically ores, with a liquid solution, such as a leaching agent. The design of Pachuca tanks features a tall, cylindrical tank with a conical bottom. The tank is equipped with a central draft tube, which extends from the bottom to near the top of the tank. This draft tube serves several purposes:

1. Agitation: The draft tube is connected to an agitator mechanism at the top of the tank, which stirs the contents of the tank. This agitation is crucial for promoting the mixing of the solid particles (ore) with the liquid solution (leaching agent), ensuring that all the particles come into contact with the solution. Without proper mixing, the leaching process would be inefficient, leading to incomplete extraction of the desired metals.
2. Gas Dispersion: In some processes, such as bioleaching or oxidation processes, gases like air or oxygen may be introduced into the tank to facilitate chemical reactions. The draft tube helps distribute these gases throughout the tank, ensuring uniform contact between the gases and the solid-liquid mixture.
3. Settling Prevention: The upward flow created by the draft tube helps prevent settling of solid particles at the bottom of the tank. This ensures that the solid-liquid mixture remains homogeneous, maximizing the efficiency of the leaching process.

Overall, Pachuca tanks are essential equipment in hydrometallurgical processes, particularly for leaching operations where thorough mixing of solid particles with liquid solutions is required to extract valuable metals from ores. Their design allows for efficient agitation and gas dispersion, contributing to higher extraction yields and process efficiency.