Extracting copper

Question 1

Describe

• Describe the processes involved in the extraction of copper – hydrometallurgy

Answer 1

Oxide ores are generally processed using hydrometallurgy. This process uses aqueous (water-based) solutions to extract and purify copper from copper oxide ores at ordinary temperatures, usually in three steps: heap leaching, solvent extraction, and electrowinning.

Question 2

Describe

• Describe the three main steps of hydrometallurgy – heap leaching, solvent extraction and electrowinning

Answer 2

The hydrometallurgy procces begins with heap leaching, where the copper is exposed to a suitable solvent (sulfuric acid) The solvent, selectively dissolves the metal of interest while leaving impurities behind. Once the metal is leached into the solution, it undergoes solvent extraction to remove impurities such as undesired metals, non-metallic elements, and organic compounds.The last step is called electrowinning, a type of electrolysis. An electrical current passes through an inert anode (positive electrode) and through the copper solution from the previous step, which acts as an electrolyte. Positively-charged copper ions (called cations) come out of solution and are plated onto a cathode (negative electrode) as 99.99% pure copper.

Question 3

Describe

• Write word equations to summarise the reactions occurring during these processes

Answer 3

.copper oxide + sulfuric acid → copper sulfate + water

Question 4

Describe

• Describe the process of electrowinning in detail

Answer 4

Electrowinning (or electroextraction) is a process whereby metals, such as gold, silver and copper, are collected from a solution by means of electrolytic chemical reaction. This takes place when an electric current is passed through the solution.