Final answer:
The electrowinning process uses an electrolytic cell for gold refining, where steel wool serves as the cathode and an acid solution is used to dissolve the gold. Electric current causes gold ions to plate onto the cathode. Careful control of solution composition and voltage ensures high-quality gold deposition.
Step-by-step explanation:
The electrowinning process for gold refining is an application of electrolysis. In this process, an electrolytic cell is used, which consists of an anode and a cathode submerged in a solution.
The cathode is typically made of wire wool or fine steel wool, which acts as the surface where gold deposits. The wool is generally composed of steel with high surface area to facilitate the plating process. The anode, on the other hand, is where oxidation occurs, resulting in the dissolution of gold into the solution.
During electrowinning, an acid solution is used to dissolve the gold into ions. Common acids used include hydrochloric acid or sulfuric acid. However, the specific acid and its concentration depend on the design of the electrorefining process.
As electric current passes through the solution, gold ions migrate towards the steel wool cathode, where reduction occurs, plating the steel wool with a layer of pure gold. The plated gold is then removed, refined further if necessary, and processed into bars or other products.
The entire process is driven by electrochemical principles, where the flow of electric current prompts the transfer of metal ions and the deposition of solid gold onto the cathode.
It is critical for the environment in the electrolytic cell, such as the composition of the electrolyte solution and the applied cell voltage, to be controlled carefully to ensure the high quality of the gold coating.