The key difference between carbothermic and metallothermic reduction is that in carbothermic reduction, the reducing agent is carbon, whereas, in metallothermic reduction, the reducing agent is a metal.
Carbothermic reduction and metallothermic reduction are very important reactions in obtaining pure metal. These reactions are applied mainly in industrial processes.
CONTENTS
1. Overview and Key Difference
2. What is Carbothermic Reduction
3. What is Metallothermic Reduction
4. Side by Side Comparison – Carbothermic vs Metallothermic Reduction in Tabular Form
5. Summary
What is Carbothermic Reduction?
Carbothermic reduction reaction is a type of chemical reaction in which the reduction of substances such as metal oxide occurs in the presence of carbon. Here, carbon tends to act as the reducing agent. Usually, this type of chemical reactions occurs at very high temperatures. These carbothermic reduction reactions are very important in the production of the elemental forms of many elements. We can easily predict the ability of metals to participate in carbothermic reactions using Ellingham diagrams.
Ellingham diagram is a graph that shows the temperature dependence of the stability of compounds. Generally, this analysis is useful in elevating the ease of reduction of metal oxides and sulfides. The name comes from its discovery by Harold Ellingham in 1944.
Figure 01: An Ellingham Diagram
Carbothermic reduction reactions are able to produce carbon monoxide and even carbon dioxide sometimes. We can describe the conversion of the reactants into the products regarding the entropy change. In this reaction, two solid compounds (metal oxide and carbon) convert into a new solid compound (metal), and a gas (carbon monoxide or carbon dioxide). The latter reaction has high entropy.
There are many applications of carbothermic reduction reactions, including iron ore smelting as the major application. Here, iron ore is reduced in the presence of carbon as the reducing agent. This reaction gives iron metal and carbon dioxide as products. Another important example is the Leblanc process where sodium sulfate reacts with carbon, giving sodium sulfide and carbon dioxide.
What is Metallothermic Reduction?
Metallothermic reduction reaction is a type of chemical reaction that is conducted to obtain a target metal or alloy from feed material such as oxides or chlorides through using a metal as a reducing agent. Most of the reactive metals are obtained through this reduction process. E.g. titanium metal.
A common example of this type of reaction is the purification of niobium metal. In this reduction reaction, niobium oxide is reduced by aluminum metal to give niobium metal and aluminum oxide. It is an exothermic reaction where oxide impurities slag, and we can remove them from the molten niobium metal.
What is the Difference Between Carbothermic and Metallothermic Reduction?
Carbothermic reduction and metallothermic reduction are very important reactions in obtaining a pure metal. Carbothermic reduction reaction is a type of chemical reaction in which the reduction of substances such as metal oxide occurs in the presence of carbon. A metallothermic reduction reaction, on the other hand, is a type of chemical reaction is conducted to get a target metal or alloy from feed material such as oxides or chlorides through using a metal as a reducing agent. The key difference between carbothermic and metallothermic reduction is that in carbothermic reduction the reducing agent is carbon whereas in metallothermic reduction the reducing agent is a metal.
Below infographic summarizes the differences between carbothermic and metallothermic reduction in tabular form.
Summary – Carbothermic vs Metallothermic Reduction
Carbothermic reduction and metallothermic reduction are very important reactions in obtaining a pure metal. The key difference between carbothermic and metallothermic reduction is that in carbothermic reduction, the reducing agent is carbon, whereas, in metallothermic reduction, the reducing agent is a metal.
Reference:
1. “Metallothermic Reduction.” Science Direct, Available here.
Image Courtesy:
1. “Ellingham Richardson-diagram english” By DerSilberspiegel – {{Self-made with most data from here [1]}} (CC BY-SA 4.0) via Commons Wikimedia