Steel Processing facilities are part of a worldwide important and material intensive industrial sector. During the production process the semifinished parts and intermediate products (e.g. hot-rolled steel panels) have to be cleaned from superficial oxide films before subsequent processing is possible. The cleaning is performed with pickling liquor (e.g. hydrochloric acid), which is enriched with Iron-II-Chloride (FeCl₂) and Water (H₂O) during this procedure. For economic reasons the resulting wasted liquor is not disposed, but regenerated in Spray Roasting Reactors.

The pickling liquor enters the natural gas fired burners through atomization nozzles and reacts to Iron-III-Oxide-Particles (Fe₂O₃) and hydrochloric acid. The regenerated hydrochloric acid is fed into the pickle again. The particles are valuable by-products and can serve as resources in the pigment industry or to produce magnetic products if obtained in sufficient qualities.

In the past the design of Spray Roasting Reactors was based on empiric data and experience of line operations, since a detailed analysis of the particle formation process is difficult. It is not possible to analyse the reaction within a Spray Roasting Reactor during the running process, therefore important data to optimize the operating conditions with respect to particle qualities is missing. Further information of temperature – and concentration characteristics of the droplets is vital for the properties of the resulting particles.

To obtain further knowledge of the iron oxide formation a laboratory reactor was developed, which simulates the boundary conditions relevant for industrial Spray Roasting Reactors. Temperature, gas composition and droplet size are comparable to those in industrial applications.

Furthermore several numerical simulations of Spray Roasting Reactors were performed, which provide information of stream – and temperature proportions in the reactor and show relevant particle trajectories. Combined with the experimental data the iron oxide formation process can be optimized and important modifications of technical facilities are extracted.