The "Flashing" system allows to obtain a surface coloring of the bricks different from that obtained with oxidizing firing: thanks to the action of the reducing atmosphere induced in the kiln, the ferric oxides present on the surface of the piece undergo a partial reduction process: in fact there is a partial formation of magnetite and hematite.
These oxides are dark in color and give a darker color to the product. In addition, the rise in temperature resulting from Flashing gives the brick greater shine and brilliance.
The company COSMEC supplies the "Flashing" system complete, ready to be installed on the kiln, including automatic adjustment systems and functional safety devices.
The “Flashing” will be obtained thanks to one or more groups of burners (replacing existing groups), placed on the ceiling at the final part of the firing area. These groups will function as normal burners during oxidative firing, while during the “Flashing” they will operate at a higher gas pressure and will be able to deliver a much higher fuel flow rate, while limiting the combustion air to a minimum.
This operation will be activated for an adjustable time before and after the push. At the same time the amount of air coming in from the kiln cooling area will be reduced, limiting the back pressure, recovery and rapid cooling fans.
The system will operate with pre-setting of the times and flow rates of the fans while the burners will be regulated by the temperatures read in the concerned area.
To verify the achievement of the reducing atmosphere in the affected area is planned the installation of a continuous O2 Zirconium oxide analyzer.
A sampling system with smoke sampling in the areas adjacent to the "Flashing" area will verify the quantity of CO produced, and the absence of unburnt gases in the pipes which, if present, could be dangerous from the point of view of safety and toxicity.
The whole system is studied to work automatically to reproduce the conditions that allow the best results to be obtained over time.
