Chrome free organic tannages and molecular level understanding of the tanning process for the production of leather with high hydrothermal stability Samir DasGupta , New Zealand Leather and Shoe Research Association
It is rather strange that today I am talking about chrome-free tannages when I have devoted my whole life to improving the chrome-tanning system. When I was a student, I wondered why chrome tanned leather that stood the boil, did so only for about 1 to 2 minutes. My ambition was to find out how leather could be treated like textile, and we discovered and patented a product and process for improving the hydrothermal stability of chrome-tanned leather. This patent showed how chrome tanned leather could be boiled like textile for an hour without area loss. At LASRA we have also developed LASRA ThruBlu and modified ThruBlu processes to minimise the environmental impact of chrome tanning.
Combined organic tanning based on mimosa and oxazolidine: development of a semi-industrial scale process for high-quality bovine upper leather
In this study we present an industrial-scaled tanning process intended to replace chrome tanning in the production of high quality bovine shoe upper leathers using a combined tannage based on a mimosa and oxazolidine as cross-linking agent. This paper reports the best recipe developed and the properties of the leather obtained. The various test results and scanning electron microscopy (SEM) observations which were used as investigative methods to follow the tanning process steps and to better understand the cross-linking mechanisms, are detailed together with the characterisation of the effluents. The leather obtained is characterised by a good hydrothermal stability coupled with good physical and technical properties which allow it to easily comply with the standards required for high quality chromium-tanned bovine upper leather. The results obtained suggest that this tannage is a promising alternative to traditional chrome tanning.
Thermodynamic Assessment to Chromium Oxidation in the Production of Stainless Steel
A solution model called ε approach is applied to predict the thermodynamic solution behaviour of Cr in steel melts. The calculated results are supported by the available experimental results. Further predictions on chromium scorification are achieved in view of melting and refining processes for Cr‐containing steels. Chromium reduction from slags after meltdown during EAF melting and AOD or VOD refining treatment is important for the production of Cr‐containing steels. It is thermodynamically predicted that chromium is inevitably oxidized during decarburization process which coincides with the industrial and experimental results. Minimum oxidation of chromium can be reached by lowering the partial pressure of CO gas at high temperatures.