What is the Difference Between Electrowinning and Electrorefining

The key difference between electrowinning and electrorefining is that in the electrowinning process, the impure metal is in the leach solution, whereas in the electrorefining process, the impure metal is the anode.

Electrowinning is the electrodeposition of metals from the ores that have been put in a solution via leaching. Electrorefining is the electrodeposition of metals from the ores that have been put in a solution to remove impurities from the metal ore.

CONTENTS

1. Overview and Key Difference
2. What is Electrowinning
3. What is Electrorefining
4. Electroforming vs Electroplating in Tabular Form
5. Summary – Electrowinning vs Electrorefining

What is Electrowinning?

Electrowinning is the electrodeposition of metals from the ores that have been placed in a solution via leaching. It is also named electroextraction. It uses electroplating on a large scale and is an important technique for the economical and straightforward purification of non-ferrous metals. In this process, an electrical current passes from an inert anode (it is where the oxidation occurs) through a leach solution consisting of dissolved metal ions. Then the metal is recovered as it is deposited in an electroplating process onto the cathode where the reduction occurs. The metal that results from the process is known as an electrowon.

When considering the applications of the electrowinning process, the most commonly used metals for this process are lead, copper, gold, silver, zinc, aluminum, chromium, cobalt, manganese and some rare earth metals and alkali metals. More importantly, this is the only process that we use for aluminum metal.

What is Electrorefining?

Electrorefining is the electrodeposition of metals from the ores that have been put in solution to remove impurities from the metal ore. This process uses a similar process to that of the electrowinning process. It is important in the economical and straightforward purification of non-ferrous metals.

In the electrorefining process, the anode contains the impure metal to be refined. We can use metals like copper for this process. Thereafter, the impure metallic anode undergoes oxidation, and then the metal tends to dissolve into a solution. Moreover, the metals ions migrate through the acidic electrolyte until it reaches the cathode, where we can get the deposited metal. In addition, the insoluble solid impurities that tend to sediment below the anode often consist of valuable rare elements, including gold, silver, and selenium.

The electrorefining process allows us to separate heavy metals, including plutonium, caesium, and strontium, from the less-toxic bulk of uranium. Moreover, it can be used to remove toxic metals from industrial waste streams.

What is the Difference Between Electrowinning and Electrorefining?

Electrowinning and electrorefining are important industrial processes useful in obtaining a pure metal from impure metal ore. The key difference between electrowinning and electrorefining is that in the electrowinning process, the impure metal is in the leach solution, whereas in the electrorefining process, the impure metal is the anode. Moreover, in electrowinning, an electric current passes through leach solution from anode to the cathode, where the pure metal is deposited on the cathode, while in electrorefining, impure metal is the anode, and it gets oxidized to dissolve the metal into the solution, followed by the movement of metal ions through the electrolyte towards the cathode for pure metal deposition.

The below infographic presents the differences between electrowinning and electrorefining in tabular form for side by side comparison.

Summary – Electrowinning vs Electrorefining

Electrowinning is the electrodeposition of metals from the ores that have been put in solution via leaching. Electrorefining is the electrodeposition of metals from the ores that have been put in solution to remove impurities from the metal ore. The key difference between electrowinning and electrorefining is that in the electrowinning process, the impure metal is in the leach solution, whereas in the electrorefining process, the impure metal is the anode.

Reference:

1. “Electrowinning.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Electrorefining technology anl gov” By Argonne National Laboratory –  Flickr account (CC BY-SA 2.0) via Commons Wikimedia
2. “Copper Raffination” By Maxiantor – Own work (CC BY-SA 3.0) via Commons Wikimedia