Removing ammonia from coke oven effluents - by removing free ammonia, then mixing the effluent with calcium hydroxide in an aq. suspension of solid material to liberate bound ammonia

摘要

Process for removing NH3 from effluent waters from coke ovens comprises (1) removing unbound NH3, e.g. by desorption by steam heating and (2) liberating bound ammonia by passing the effluent water together with Ca(OH)2 to a mixing vessel contg. a suspension of solid material in water. Pref. the amt. of Ca(OH)2 used is 1.0-2.0, esp. 1.0-1.2 gm. equivs. per gm. equiv. NH3. The aq. suspension is pref. a suspension of poorly soluble Ca salts. Process allows the bound NH3 to be liberated with Ca(OH)2 in place of the more expensive NaOH previously used. The use of a mixing vessel contg. suspended solids for the ammonia liberating stage avoids problems of blockage of the appts. with insoluble Ca salts previously encountered when using Ca(OH)2 as ammonia liberating agent.