Recycling of Spent Unhairing-Limming Liquor

F. E. Faki, A. E. Musa, G. A. Gasmelseed, I. H. Elamin

Unhairing – limming process is the most polluting operation in leather industry. In hair burn unhairing -limming method, lime and sodium sulphide and a huge amount of water are used to destroy and remove hair from hides and skins generating a large amount of effluent. Sodium sulphide is harmful to human and environment. As an effective substitution to sulphide has not yet been developed, recycling of lime – sulphide liquor has become one of the better options for pollution control. In the present study, direct recycling of unhairing – limming liquors was carried out. The liquors were reused 7 times after had been replenished with reduced quantities of chemicals and water. An average savings of about 28% in sodium sulphide, 32% in lime and 75% in water were obtained. The quality of crust leathers produced by recycling of limming liquor has not been changed comparing to control leathers.