What is the type of metallurgy in which the ore is leached and the metal is collected by using electrolysis?

Hydrometallurgy

The correct answer is option 1. Hydrometallurgy.

Hydrometallurgy is a branch of metallurgy that involves the extraction of metals from their ores using aqueous solutions. It encompasses various processes, including leaching and electrolysis, to recover metals in a purified form. Here's a detailed explanation of each step involved in hydrometallurgy:

Leaching:

Leaching is the initial step in hydrometallurgical processes, where the ore is treated with a suitable solvent to dissolve the desired metal compounds. The choice of solvent depends on the nature of the ore and the metal to be extracted. Common solvents include sulfuric acid, hydrochloric acid, cyanide solutions, and alkalis. The leaching process can be carried out through different methods:

Heap Leaching: Crushed ore is piled into heaps and irrigated with the solvent solution. The metal-containing solution, known as the "pregnant" or "rich" solution, percolates through the heap and collects at the base, carrying the dissolved metal ions.

Tank Leaching: The ore is ground into fine particles and mixed with the solvent in tanks or vats. Agitation or air bubbling may be employed to enhance the contact between the ore and the solvent, speeding up the leaching process.

In situ Leaching: The solvent is injected directly into the ore deposit, where it dissolves the metal ions in situ. The pregnant solution is then pumped to the surface for further processing.
During leaching, the metal ions in the ore dissolve into the solvent, forming a metal-rich solution known as the "pregnant" or "rich" solution. Meanwhile, gangue minerals remain undissolved or dissolve to a much lesser extent.

Purification:

After leaching, the pregnant solution containing the dissolved metal ions may undergo purification steps to remove impurities such as other metal ions, organic compounds, or solid particles. Purification techniques may include precipitation, solvent extraction, ion exchange, or other chemical treatments to selectively separate the target metal ions from the impurities.

Electrolysis:

Once the pregnant solution is purified, electrolysis is employed to recover the metal from the solution in a pure form. Electrolysis involves passing an electric current through the purified solution (electrolyte) using electrodes immersed in the solution.The metal ions present in the electrolyte migrate towards the cathode (negative electrode) under the influence of the electric field. At the cathode, they gain electrons and are reduced to form pure metal atoms or deposits on the electrode. Meanwhile, negative ions from the electrolyte migrate towards the anode (positive electrode) and are oxidized. The metal deposited on the cathode can be periodically removed and further processed to obtain the desired metal product.

In summary, hydrometallurgy involves the extraction of metals from ores using aqueous solutions, primarily through the processes of leaching and electrolysis. Leaching dissolves the metal compounds from the ore, while electrolysis recovers the metal from the solution in a purified form through electrochemical deposition. This method is widely used for the extraction of various metals, including copper, nickel, zinc, gold, and uranium, among others.