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University Of Gezira (2005)

Extraction of Tannins From Garad Pods (Acacia-Nilotica) For Large Scale Production

Tayseer Hassan Belal Ali

Titre : Extraction of Tannins From Garad Pods (Acacia-Nilotica) For Large Scale Production

Auteur Tayseer Hassan Belal Ali

Université de soutenance : University Of Gezira

Grade : M.Sc 2005

Résumé
The tanneries in the Sudan imported mimosa and synthetic (syntan) tannins material for the process of retanning and pretanning. It is observed that the sunt (acacia-nilotica) tree produces a fruit cold garad pods. This garad pods has a high amount of tannin content and high amount of sugar. From the experience of rural tanneries, it is observed that the skins which are pretanned and retanned with garad tan are of good quality. In the early sixties the first mechanized tannery in Khartoum which is Khartoum-tannery started to use garad grain powder in the pretannage process. This application continued until the early seventies ; when garad grain powder was used for retannage and pretannage. However, the application of garad grain powder in this form created a problem of drainage blocking and found to be not suitable for continuous processes. To solve this problem the grain powder was leached, concentrated in a triple-effect evaporator and further may be spray dried. The concentrated solution obtained can be used for both pretannage and retannage without any problem of drainage blocking. In this study ; the factors that affect leaching which are mainly time, solvent to solid ratio, temperature and agitator speed are investigated. It is found that at solvent to solid ratio of 6:1, moderate agitator speed (200-250 rpm), temperature of (40° C to 50° C), and the time required for leaching is one hour. A complete design of a long tube triple-effect evaporator is made for production of 1000 tons per year which is enough for the present level of capacities in the tanneries to date.

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Page publiée le 12 avril 2018