Combustion is an oxidation reaction at high temperature in the presence of enough oxygen to fully oxidise the components. It results in energy in the form of heat and in CO₂, water and ash as products.

Combustion via HECO technology provides energy sources based on biomass waste. It can also be used to eliminate the organic content of materials such as molding sand, with the original material then being released for reuse.

The main advantages of using HECO technology in combustion processes are:

• The input gases are heated using hot solids dropped through the annulus (heat exchange effect), thus reducing the amount of energy needed and enabling combustion to take place at lower temperatures.
• Dry ash is obtained rather than slag, because combustion takes place at lower temperatures than with other technologies.
• NO_x levels are lower because of the lower temperature and the regulation of the stoichiometric flow rate of the air.
• This reduces problems of particle agglomeration and fusion.

The construction industry, particularly the cement industry, is looking for alternative technologies for valorising moulding and foundry sand. At present less than 40% of this waste is valorised. This entails a substantial risk for the environment.

HECO technology brings numerous innovations to the process of recovering moulding sand. On the one hand the characteristic, strong circular movement of particles in the HECO contactor makes for more efficient contact between gases and solids, which increases reaction kinetics and drying, with shorter hold times for solids in the reactor. On the other, that movement decreases agglomeration and the internal design of the system can be adapted to maximise wear, with no internal or external mechanical parts. This facilitates the release of reactant material from the particles and improves elimination.