Mond’s Process: Principle, Application

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Mond's process

Mond’s process is used to extract and purify nickel. In this process, nickel oxide is converted into pure nickel. This procedure takes advantage of nickel’s easy and reversible complexation with carbon monoxide that results in nickel tetracarbonyl.

In 1890, Ludwig Mond invented Ni(CO)4 while examining nickel valves’ rapid corrosion in the Solvay process. Unlike other nickel compounds, often green solids, Ni(CO)4 is a colorless, volatile, and poisonous liquid with an “organic character”. He developed the “Mond process” for the purification of nickel.

The process involves the burning of nickel ore in carbon monoxide to form nickel carbonyl vapor, which is subsequently decomposed at a higher temperature to yield the metal. As this process involves the use of CO, it is also known as the carbonyl process.

Carbon monoxide and nickel react at 50-60 degrees Celsius in the Mond Process to generate nickel tetracarbonyl gas. This separates nickel from impurities, none of which generate carbonyls at such low temperatures. Heating nickel tetracarbonyl to 220-250 degrees Celsius decomposes it into pure nickel and carbon monoxide.

The Mond technique is commercially used using a nickel decomposer, which gradually grows pellets by pre-heating seed pellets to the required nickel carbonyl gas decomposition temperature and passing them through a chamber where a layer of pure nickel is deposited on the surface.

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Principle and Process of Mond’s process

Mond’s process is based on the principle that when impure nickel is treated with CO (Carbon monoxide) only nickel combines with CO to form volatile nickel carbonyl, no other compounds form carbonyl compounds under the mild conditions used in this process.

This process involves three steps:

  1. Nickel oxide is reduced with water gas (H2O + CO)  at 200  degrees Celsius to give impure nickel which contains iron and cobalt as impurities.

2 NiO + CO → 2 Ni (impure nickel) + H2O + CO

  • This impure nickel is treated with CO to form nickel tetracarbonyl. Which is volatile

the toxic gas, skipped out leaving behind all impurities in the solid state.

Ni + CO → Ni (CO)4

  • This nickel tetracarbonyl on heating at 220-250 degrees Celsius decomposes to give pure nickel.

Ni (CO)4 →Ni + 4 CO

Nickel Plating

Nickel can withstand corrosion from a range of organic compounds, alkalies, and fluorine. It remains brilliant indoors but tarnishes outdoors, despite having an extremely low corrosion rate. Its low corrosion rate, combined with its resistance to corrosion by sodium chloride and other chlorides commonly found on winter roads, make it a vital undercoat for chromium-plated vehicle trim.

Nickel electroplating technology has advanced significantly, enabling the efficient production of a wide range of industrial coatings for both ornamental and functional uses. This widespread application demonstrates nickel’s advantageous qualities and versatility as a coating material. nickel coatings are used to improve physical qualities such as resistance to wear, heat, or corrosion. In many key applications, nickel coating serves a dual purpose. It provides a bright, appealing surface while also improving corrosion resistance or other useful characteristics.

Electroless nickel plating deposits nickel without the use of an electric current. Electroless nickel plating does not require an external current source, as galvanic electroplating does. Electroless nickel plating is often referred to as chemical or autocatalytic nickel plating.

Electroless nickel coatings are exceedingly uniform, even when applied to complex-shaped products. The procedure employs chemical nickel plating baths. The most popular method for depositing electroless nickel is the catalytic reduction of nickel ions with sodium hypophosphite in acid baths at pH 4.5-5.0 and temperatures ranging from 85 to 95°C.

The most common application of nickel plating is computer hard disc drives, but other examples include electroplating plastics, automotive brake cylinders, pumps, valves, and other industrial goods. Electroless nickel plating is very resistant to wear and corrosion while adhering to all metals. This includes metals such as aluminum, which is becoming increasingly significant in the automotive and aerospace industries due to its lightweight nature.

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Kabita Sharma

Kabita Sharma, a Central Department of Chemistry graduate, is a young enthusiast interested in exploring nature's intricate chemistry. Her focus areas include organic chemistry, drug design, chemical biology, computational chemistry, and natural products. Her goal is to improve the comprehension of chemistry among a diverse audience through writing.

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