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Content archived on 2024-05-27

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


General: During the project, VAL has established contacts with PQ Corp (Head quarter in USA, European R&D – HQ in Maastricht/ NL. PQ is the world largest producer of silicates and strongly interested in cooperation). In various discussions with PQ, it could be made clear that the type of Wasserglass (ratio Na2O/SiO2) has only very little influence on the penetration results. Much more important is a very slow neutralization, which leads to a uniform silicate – distribution in the cross section of the pelts. This was certified by SEM/ microprobe analysis by VAL, carried out in cooperation with a specialized institute.

Work package 1 – Process Optimization and Implementation:
For chrome – tanned shoe upper leather from bovine hides the procedure has already been developed and semi – technical trials have shown a leather quality comparable with those from commonly produced leather (partners LGR + HEINEN)
Chrome and chrome-free automotive leathers (partners VAL + VOGL, supported by BOEHME) have shown some weaknesses in the process reliability, but it seems that with slow neutralization and horsing this problem can be overcome. These partners agreed to continue this development after the project end.

Procedures for shoe upper leather from calf skins (SSIP + NOBEL) and for garment leather from sheep skins (SSIP + HAMANA) have been improved remarkable and are in the state of technical implementation. Especially in terms of chrome tannage, 30 % reduction in the chrome tannin offer has already been proofed. Samples of all partners have been presented at the final meeting.

Reduction on effluent loading could be verified at all trials and is presented in details in the Final Report. In addition, comparative analysis regarding sludge volumes also indicate decreasing volumes from the combined tannery effluent treatment.

Work package 2 – Utilization of Shavings:
The procedure for controlled hydrolysis has been optimised by VAL, and bigger batches have been already sent to BOEHME. In semi-technical trials, it could be shown that these hydrolysates can not only substitute products from chrome shavings, but also show much better effects when applied in leather technology. According to BOEHME, one of the biggest advantages is that their usually applied protein hydrolysates are produced from chrome shavings, and this requires high efforts on de-chroming. This is not necessary with the native shavings from the Wasserglass – procedure.

At SSIP, also hydrolyzation trials have been carried out with excellent results, and application trials have been carried out with auxiliary producers and the cosmetic industry.
Fertilizing trials have been carried out by SSIP and show excellent results, whereat especially the Nitrate-contamination of soil (in comparison with commercial products) could be reduced significantly.

Work package 3 – Lime substitution:
Trials in semi-technical scale with Wasserglass, substituting lime in common liming and drum painting as well (carried out by VAL + VOGL and LGR + HEINEN), have shown that with Wasserglass, a fully satisfying unhairing and opening up could be obtained, whereat the higher cleanness of the grain and improved splitting accuracy are additional advantages. However, the application of Wasserglass in liming or painting is not sufficient to save the penetration step of pelts for shaving.

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Participants (6)