Recovery of tar: the coke oven gas coming out from ovens is passed through a tower where liquid ammonia is sprayed. The tar and dust are removed and then recovered.

Recover of NH₃: the gases are then passed through a tower in which water is sprayed. It is removed as ammonia hydroxide.

                                 NH₃ + H₂O    NH₄OH

Instead Of Water, If Sulphuric Acid Is Sprayed, It forms Ammonium Sulphate Which Can Be Recovered.

                                 2NH₄OH + H₂SO₄   (NH₄)₂SO₄ + 2H₂O.

Recovery of Naphthalene:  after removal of nh3, the gases are passed through a cooling tower where water at low temperature is sprayed. Naphthalene and some condensed gases are recovered.

Recovery of benzene: it can be recovered by passing the gas through chamber where petroleum is sprayed.

Recovery of H2S :  the gas is passed through chamber containing moist Fe₂O₃, where it is recovered

                                 Fe₂O₃ + 3H₂S  Fe₂S₃ + 3H₂O

                     Fe2O3 can be regenerated by treating Fe2S3 with air

                                 Fe₂S₃ + 4O₂ 2FeO + 3SO₂

                                 4FeO + O₂  2Fe₂O₃

The coal gas is recovered and collected in a gas holder after passing through various chambers to removed the by- products. The calorific value of the gas is 5000 kcal/m³.