All industrial thermal processes, (cooking, combustion, curing…) generate naturally acidic contaminated gases (fluorine, chlorine, sulphur…). These gases cannot be directly emitted into the atmosphere until they comply with a series of requirements and emission limits. The various gas treatment systems can be divided as: wet, semi-wet, semi-dry and dry. Within these systems, different products can be used from calcium carbonates to quick and hydrated lime, both injected in whitewash form.