Mond Process: Definition, Principle And Steps

Metals were in high demand during the rise of the industrial revolution because they are rigid and malleable, and they are used for a wide range of applications and products. Nickel is one such metal, which is mostly used in alloy formation with other metals. To obtain pure nickel metal, refining processes of metal ores were required.

The Mond process is used to refine nickel metal from its mixed state. It is also known as a carbonyl process because the metal is first bound to carbon monoxide before being heated to remove all impurities associated with nickel metal. Ludwig Mond invented this process in 1890, during the era of metallurgical processes.

What exactly is “The Mond Process”?

The Mond process is the process of extracting, refining and purifying nickel metal from its mixed ore in a pure state.

Principle of the Mond Process for Refining Nickel

The Mond Process is based on the following principles:

i. It is based on the principle of vapour phase refining:

This method is based on the fact that certain metals are converted to their volatile compounds while impurities remain unaffected.

ii. Column chromatography for rare element purification:

This chromatography technique is based on the principle that different components of a mixture are adsorbed differently on an adsorbent. The mixture’s components are adsorbed in various locations on the column.

Steps Involved in the Mond Process

To refine nickel metal from its mixed ore state, the Mond process is required. It consists of three major steps, which are described in detail below:

First Step;

The first step is to treat mixed oxide ore with the Syngas mixture. At 200°C, the syngas, a mixture of hydrogen gas and carbon monoxide gas, is combined with nickel oxide, which contains the impurities iron and cobalt.

Reaction Process;

At 200°C syngas, a mixture of hydrogen and carbon monoxide gas, is combined with nickel oxide, which contains the impurities iron and cobalt.


Second Step;

The second step is a chemical transport reaction, which is a special type of reaction. At a relatively low temperature of around 50-60 degrees Celsius, the impure concentrated metal ore is dropped in a mixture of the other constituent of syngas, which is carbon monoxide. The impure metal ore forms a complex called nickel carbonyl during this process, and other impurities are removed as solid counterparts. Such complexes are formed by nickel metal, which has a high affinity for strong bonding ligands in square planar geometry.

Reaction Process;

Carbon monoxide reacts with impure nickel to form nickel tetracarbonyl, leaving the impurities as solids.

Ni(s)+4CO(g) → Ni(CO)4(g)


Third step;

The third step is a straightforward thermodynamic process that is dependent on the stability of the nickel carbonyl complex. The complex degrades at a temperature of 250 degrees Celsius. The pure Nickel metal is extracted from the mixture at this temperature.

Reaction Process;


The syngas and nickel carbonyl mixture is heated. This causes the decomposition of carbon monoxide and nickel.

Ni(CO)4(g) →Ni(s)+4CO(g)


To continue the process, pure nickel is collected and carbon monoxide is recycled.

Because this method can extract and purify nickel.

Frequently Asked Questions

What Metal is Refined by the Mond Process?

Ans: The metal refined by the Mond or carbonyl processes is nickel.

What is the purpose of CO Gas in the Mond Process?

Ans: Impurities in metals are removed using carbon monoxide (CO).

Who Invented the Mond Process?

Ans: The method was developed by the German-British chemist Ludwig Mond (1839–1909).

What happens when CO gas reacts with heated nickel metal?

When carbon monoxide is heated over finely divided nickel, nickel tetracarbonyl is formed.