Climate change presents all energy and greenhouse gas-intensive industries with the challenge
of improving the climate-friendliness of their production processes. With a share of 7 % of the
global CO2-emissions each, the iron and steel industry and the cement industry both hold a key
position in this regard. In addition to the intrinsic motivation of the companies, extrinsic factors, e.g. changes in the legal requirements or the growing interest towards sustainability shown by investors, also play an important role.
The „green transformation” in the iron and steel industry is leading to new production processes, such as direct reduced iron ore using hydrogen gas and the expansion of electric arc furnaces.
This also results in a change regarding the side-stream products. There will be a reduction in the availability of blast furnace slag, which is used in its granulated form as a substitute for clinker in the cement industry. It is therefore necessary to find and research alternatives to blast furnace slag in order to further mitigate process eminent CO2-emission in the cement industry.
During its production, granulated blast furnace slag is solidified in an amorphous state in order to develop latent hydraulic properties, that lead to its suitability as a binder material. In the past, this was achieved using a wet granulation process. Not only does this result in the loss of the useable energy of the mineral phase, but more energy is needed to dry the granulate. Dry granulation using rotary atomization, on the other hand, makes it possible to utilise the thermal energy stored in the product and save on drying energy at the same time. In dry granulation, centrifugal force is used to cause the molten material to disintegrate into droplets. The energy, which is transferred to the air during cooling can then be used as process heat.
In order to be able to study the effects of rotary atomization of residual mineral products, a corresponding system is required. The aim of this work is therefore to design, egnineer and
build a laboratory-scale rotary atomizer at the Chair of Thermal Processing Technology. It should be possible to combine the atomizer with the existing induction melting plant.
The results of the rotary atomizer tests show that the system is capable of producing particles
that meet the requirements for being used as binder materials. The properties of the particles
are furthermore in line with the calculation which were carried out beforehand.