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Wasserglass in leather production (in order to reduce tannery wastes)

Exploitable results

Shavings from common procedures are all pre - tanned (mostly with chrome - tannins). The tannin content either make any utilization very complicated (de-chroming) or impossible (no de-tanning possible). Therefore, per year nearly 100.000 tons of shavings have to be disposed in the EC only. Shavings from the wasserglass - procedure contain only small amounts of harmless alkali - silicates and are nearly completely digestible. So the native shavings can serve as starting products for various purposes, e.g. production of fertilizers, protein hydrolysates and pet chewing articles. In small scale trials, the above mentioned purposes had been successfully proved.
In common leather production, only pre-tanned shavings from leveling process of hides and skins are obtained. These shavings - about 100.000 tons per year in the EC only - are not easy to utilize and are, therefore, mainly disposed. In the present project, a procedure was developed, at which unhaired hides and skins (i.e. pelts) are penetrated with wasserglass. After the subsequent neutralization, the pelts can be shaved, and only then any required -tannage can be applied. Since the occurring shavings only contain small amounts of silicates, the can be -considered as "native" and are, therefore, easy utilizable. -The developed procedure can be carried out with already available tannery equipment and, therefore, machinery investment has to be made for the process implementation. -In all participating tanneries, the wasserglass procedure, has been developed and applied in semi-technical -scale and is, therefore, available for -shoe upper leather from bovine hides and calf skins -fancy and garment leather from hides -upholstery and automotive leather from bovine hides(This covers the major production lines in the EC)
One unexpected, but very positive outcome of the project were -the improved exhaustion of auxiliaries, applied in leather production. While for tannins, independent of their nature, saving effects up to 30 % could, be quantified, for other auxiliaries (e.g. dyestuffs) various observations during the trials make savings very likely. -reduced loading of effluent part strewns. In corn arison with effluent part streams from common procedures, in streams from the wasserglass - procedure, significant reductions in terms SS (suspended solids), TDS (total dry substance), COD (chemical oxygen demand) and residual tannins have been determined. It can be assumed that - due to these reductions - also the volume of sludge from effluent treatment will decrease. In addition, the higher exhaustion will also lead to an improved cost situation,