Analytical results for spent chrome tanning liquor during a successful recycling trial in a commercial tannery.

A barkometer is calibrated to test the strength of tanning liquors used in tanning leather.

At this point the hides are loaded in a drum and immersed in a float containing the tanning liquor.

The hides soak while the drum slowly rotates about its axis, and the tanning liquor slowly penetrates through the full thickness of the hide.

First, the feasibility of chrome liquor recycling was tested using a variety of techniques for the separation and characterization of the chromium complexes present in tanning liquors (1,12).

Fig. 4 and Table I show that throughout recycling the total neutral salt concentration in the spent pickling/ tanning liquor, expressed in terms of gram per litre or molarity, is lower than in a conventional tanning process (Run 1).