Process of purifying combustion exhaust gases

A process of purifying oxygen-containing exhaust gases produced by combustion of waste materials including garbage, industrial waste and sewage sludge, said process comprising the steps of:

• a) reacting an exhaust gas in a gas-solids suspension at a temperature from 120.degree. to 140.degree. C. and at a gas velocity from 3 to 20 m/s for a reaction time of 0.5 to 10 seconds with a mixture containing naturally occurring zeolites to remove mercury, mercury compounds and polyhalogenated hydrocarbons, wherein said mixture consists of 0.1 to 1% by weight of at least one sulfate selected from the group consisting of MnSO.sub.4, FeSO.sub.4, CoSO.sub.4, NiSO.sub.4 and CuSO.sub.4 ;
• from 10 to 20% by weight mordenite;
• from 60 to 70% by weight clinoptilolite;
• from 0 to 5% by weight montmorillonite and a remaining balance of SiO.sub.2, said naturally occurring zeolites have a median particle size (d.sub.50) from 5 to 50 micrometers and the gas-solid suspension has a mean suspension density from 0.020 to 10 kg of said solids per sm.sup.3 of said exhaust gas;
• and
• b) forming a pure gas from said exhaust gases, said pure gas containing <50 micrograms of said mercury per sm.sup.3 of said exhaust gases, polyhalogenated dibenzodioxins and dibenzofurans in a concentration of <0.1 ng TE per sm.sup.3 of said exhaust gases and a total concentration of <1 microgram PCB, PCP and PCA per sm.sup.3 of said exhaust gases.

A process of purifying oxygen-containing exhaust gases produced by combustion of waste materials including garbage, industrial waste and sewage sludge, said process comprising the steps of:

• a) reacting an exhaust gas in a gas-solids suspension at a temperature from 120.degree. to 140.degree. C. and at a gas velocity from 3 to 20 m/s for a reaction time of 0.5 to 10 seconds with a mixture containing naturally occurring zeolites to remove mercury, mercury compounds and polyhalogenated hydrocarbons, wherein the mixture contains 10 to 30% by weight of at least one member selected from the group consisting of CaCO.sub.3, CaO and Ca(OH).sub.2, from 10 to 20% by weight mordenite;
• from 60 to 70% by weight clinoptilolite;
• from 0 to 5% by weight montmorillonite and a remaining balance of SiO.sub.2, said naturally occurring zeolites have a median particle size (d.sub.50) from 5 to 50 micrometers and the gas-solid suspension has a mean suspension density from 0.020 to 10 kg of said solids per sm.sup.3 of said exhaust gas;
• b) forming a pure gas from said exhaust gases, said pure gas containing <50 micrograms of said mercury per sm.sup.3 of said exhaust gases, polyhalogenated dibenzodioxins and dibenzofurans in a concentration of <0.1 ng TE per sm.sup.3 of said exhaust gases and a total concentration of <1 microgram PCB, PCP and PCA per sm.sup.3 of said exhaust gases.

A process of purifying oxygen-containing exhaust gases produced by combustion of waste materials including garbage, industrial waste and sewage sludge, said process comprising the steps of:

• a) providing a mixture containing naturally occurring zeolites and consisting of 0.1 to 1% by weight of at least one sulfate selected from the group consisting of MnSO.sub.4, FeSO.sub.4, CoSO.sub.4, NiSO.sub.4 and CuSO.sub.4 ;
• from 10 to 30% by weight of at least one member selected from the group consisting of CaCO.sub.3, CaO and Ca(OH).sub.2 ;
• from 10 to 20% by weight mordenite;
• from 60 to 70% by weight clinoptilolite;
• from 0 to 5% by weight montmorillonite and a remaining balance of SiO.sub.2 ;
• b) reacting an exhaust gas in a gas-solids suspension at a temperature from 120.degree. to 140.degree. C. and at a gas velocity from 3 to 20 m/s for a reaction time of 0.5 to 10 seconds with said mixture to remove mercury, mercury compounds and polyhalogenated hydrocarbons, wherein said naturally occurring zeolites have a median particle size (d.sub.50) from 5 to 50 micrometers and the gas-solid suspension has a mean suspension density from 0.020 to 10 kg of said solids per sm.sup.3 of said exhaust gas;
• c) treating a portion of said mixture laden with pollutants with air as a fluidizing gas at 300.degree. to 600.degree. in a fluidized bed to regenerate the naturally occurring zeolites in said portion and, after the treating, cooling the air leaving the fluidized bed to room temperature to separate the mercury;
• d) forming a pure gas from said exhaust gases, said pure gas containing <50 micrograms of said mercury per sm.sup.3 of said exhaust gases, polyhalogenated dibenzodioxins and dibenzofurans in a concentration of <0.1 ng TE per sm.sup.3 of said exhaust gases and a total concentration of <1 microgram PCB, PCP and PCA per sm.sup.3 of said exhaust gases.