Closed loop incineration process

A process for incinerating waste materials so that substantially all of the contaminants are removed from the resulting title gas, comprising:

• (a) feeding combustible waste material into an incineration zone containing two temperature stages, the first stage operated at a temperature from about 1400.degree. F. to 2500.degree. F., and the second stage operated at a temperature from about 1500.degree. F. to 3000.degree. F., wherein recycle flue gas from a downstream combustion zone and oxygen are fed to said incineration zone;
• (b) mixing said flue gases from said incineration zone with oxygen;
• (c) passing said mixture from (b) above to a combustion zone which is operated by burning a combustible fuel;
• (d) adding oxygen to a portion of the flue gases from said combustion zone, and recycling said mixture of oxygen and flue gases to both the incineration stages such that at least a stoichiometric amount of oxygen is present in the recycle flue gases passed to both the incineration stages;
• (e) passing another portion of said flue gases from the combustion zone to a scrubbing zone wherein acid gases are removed;
• and
• (f) passing the title gases from the scrubbing zone to a purification zone containing one or more of the following stages;
• (i) a stage for removing CO and hydrocarbon gases;
• (ii) a stage for removing additional acid gases;
• and (3) a stage for removing HCl, SO.sub.x, NO.sub.x, and S.