Growing magnetite as a protective layer can useful but the process needs to be carefully managed, here we explore how.
Magnetite, also known as ferrous oxide, is a mineral with magnetic properties made up of iron and oxygen. Created by the oxidation process, the reaction can be accelerated by heat and pH imbalances. The resulting sludge is a scourge for many engineers since it can lead to reduced efficiency, corrosion and blockages. However, for others magnetite is a positive mineral. In fact it is often developed deliberately to form a protective layer inside metal equipment, particularly boilers. A magnetite layer can help ward off corrosion and equipment damage leading to considerable cost savings. In a recent blog, a Veolia Water engineer David Broster detailed how the company’s range of boiler treatment chemicals can boost magnetite formation to help with corrosion control and improved boiler performance.
Chemical Oxygen scavengers
These chemicals remove dissolved oxygen in the boiler water making conditions more favourable for magnetite formation and helping to develop the protective layer.
Alkalinity builders
Maintaining the appropriate pH range in the boiler water is crucial for magnetite formation and alkalinity builders are often used to regulate the pH level. An alkaline environment supports the formation of magnetite. Proper pH control also prevents acid corrosion and ensures the longevity of the protective layer.
Phosphates and chelating agents
Phosphates act as corrosion inhibitors and help in magnetite formation. They form a protective layer on metal surfaces, reducing the likelihood of corrosion. Chelating agents, such as EDTA, help remove metal ions that can promote corrosion and interfere with magnetite formation.
Amines
Amines are organic, volatile compounds used to protect the internals of the boiler as well as the steam and condensate return pipework. Amines are used to neutralise the acid (H+) generated by the dissolution of carbon dioxide or other acidic process contaminants in the condensate. These amines hydrolyse when added to water and generate the hydroxide ions (OH-) required for neutralisation. Amines also aid in the formation of magnetite.
Creating favourable conditions
Water treatment chemicals play a crucial role in aiding the formation of magnetite in boiler systems. By controlling dissolved oxygen levels, adjusting pH, and utilising corrosion inhibitors, these chemicals create favourable conditions for the formation of a protective magnetite layer.
