NOVELTY - Cleaning (M1) stack gases (16), comprises: (a) providing, in stack adapted to pass stack gases through first catalytic flow-through bed (24) of calcium zeolite adapted to reduce carbon oxides from stack gases; (b) providing second catalytic flow-through bed (26) in stack adapted to pass stack gases positioned adjacent to first catalytic flow-through bed; (c) providing third catalytic flow-through bed (28) in stack adapted to pass stack gas positioned adjacent to second catalytic bed; and passing stack gases e.g. volatiles from combustion of coal through first, second and third catalytic beds.    USE - The methods are useful for cleaning stack gases comprising volatiles from combustion of coal, natural gas or propane, or from a cement kiln, and for producing a fertilizer product (all claimed), where the cleaned gases are useful in a coal-fired boiler for electric power generation.    ADVANTAGE - The method: utilizes the catalyst, which effectively cleans carbon oxides, sulfur oxides, nitrogen oxides and another pollutants from stack gases, and can be reusable; increases the efficiency of the recovery of solids and liquids from the catalytic flow-through beds; and provides the recovery of methane.    DETAILED DESCRIPTION - Cleaning (M1) stack gases (16), comprises: (a) providing, in a stack adapted to pass stack gases through a first catalytic flow-through bed (24) of calcium zeolite comprising zeolite particles of a majority of 44-64 mu m in size adapted to reduce carbon oxides from the stack gases; (b) providing a second catalytic flow-through bed (26) in the stack adapted to pass stack gases positioned adjacent the first catalytic flow-through bed, where the second catalytic flow-through bed comprises a blend of 25-75% of sodium zeolite and calcium zeolite comprising zeolite particles of a majority of 65-125 mu m in size adapted to reduce nitrogen oxides from the stack gases; (c) providing a third catalytic flow-through bed (28) in the stack adapted to pass stack gas positioned adjacent the second catalytic flow-through bed, where the third catalytic flow-through bed comprises calcium zeolite comprising zeolite particles of a majority of 78-204 mu m adapted to reduce sulfur oxides in the stack gases; and (d) passing stack gases comprising volatiles from combustion of coal, natural gas or propane, or from a cement kiln sequential through the first, second and third catalytic beds, each collecting solids in the catalytic beds, and providing gas exiting the third catalytic bed with at least 90% reduction in sulfur oxides, nitrogen oxides and carbon oxide. INDEPENDENT CLAIMS are also included for:    (1) cleaning (M2) stack gases, comprising: the steps (a)-(c) as above per se; (d1) passing the stack gases sequential through the first, second and third catalytic beds, each collecting solids and liquids in the catalytic beds, and providing gas exiting the third catalytic bed with at least 90% reduction in sulfur oxides, nitrogen oxides and carbon oxide compared to the stack gases before entering the first catalytic bed; and (e1) purging solids and liquids from the first, second and third catalytic beds by intermittently passing nitrogen through the beds to remove solids and liquids collected from the stack gases by the beds;    (2) cleaning (M3) sulfur oxides from stack gases, comprising: (a2) providing in a stack adapted to pass stack gas, a catalytic flow-through bed of calcium zeolite comprising zeolite particles of a majority of 78-204 mu m adapted to reduce sulfur oxides in the stack gases; (b2) passing stack gases comprising volatiles from combustion of coal or natural gas, or from a cement kiln sequential through the catalytic flow-through bed collecting solids in the catalytic bed, and providing gas exiting the catalytic bed with at least 90% reduction in sulfur oxides; and (c2) purging solids and liquids from the catalytic flow-through bed by intermittently passing nitrogen through the beds to remove solids and liquids collected from the stack gases by the bed;    (3) an apparatus (A1) (22) for cleaning carbon oxides, sulfur oxides and nitrogen oxides from stack gases, comprising: the stack adapted to pass the stack gases comprising gases from combustion of coal or natural gas, or propane or from a cement kiln; the first catalytic flow-through bed of calcium zeolite assembled in the stack; the second catalytic flow-through bed assembled in the stack; and the third catalytic flow-through bed assembled in the stack, where the first, second and third catalytic beds are adapted to collect solids and liquids in the catalytic beds, so that stack gases exiting the third catalytic bed have at least at least 90% reduction in sulfur oxides, nitrogen oxides and carbon oxide as compared to the stack gases delivered to the first catalytic flow-through bed;    (4) an apparatus (A2) for cleaning carbon oxides, sulfur oxides and nitrogen oxides from stack gases, comprising: the stack adapted to pass the stack gases; the first catalytic flow-through bed assembled in the stack adapted to pass stack gases through the first catalytic flow-through bed that is adapted to reduce carbon oxides, aluminum oxide and methane gas from the stack gases; the second catalytic flow-through bed assembled in the stack; the third catalytic flow-through bed assembled in the stack, where the first, second and third catalytic beds are adapted to collect solids in the catalytic beds, so that stack gases exiting the third catalytic have at least 90% reduction in sulfur oxides, nitrogen oxides and carbon oxide; and an input to intermittently purge the first, second and third catalytic beds with nitrogen to remove liquids and solids collected in the first, second and third catalytic beds;    (5) an apparatus (A3) for cleaning sulfur oxides from stack gases, comprising: the stack adapted to pass the stack gases; and the catalytic flow-through bed of calcium zeolite assembled in the stack to reduce sulfur oxides in the stack gases, where the catalytic flow-through bed is adapted to collect solids from the stack gases exiting the catalytic flow-through bed have at least at least 90% reduction in sulfur oxides compared to the stack gases delivered to the catalytic flow-through bed through the stack;    (6) an apparatus (A4) for cleaning sulfur oxides from stack gases, comprising: the stack adapted to pass the stack gases; the catalytic flow-through bed of calcium zeolite assembled in the stack; and the input that provides nitrogen to intermittently purge the catalytic flow-through bed with nitrogen to remove sulfur compounds collected on the catalytic flow-though bed; and    (7) a fertilizer product.    DESCRIPTION OF DRAWING(S) - The figure shows an enlarged portion of part of the stack gas cleaning and recovery apparatus.    Stack gases (16)    Apparatus (22)    First catalytic flow-through bed (24)    Second catalytic flow-through bed (26)    Third catalytic flow-through bed (28)