Cr-removing Of Tanning Leftovers And Regeneration Of Chrome Tannery Agent

Tanning leftovers of which collagen and chromium are the primarycomponents are the main solid excised materials of tanning industry. Theleftovers are tough to be reutilized as chromium being toxic and combinedwith the peptide bonds. Nowadays land-filling or cremating are the favoritemeans of disposing tanning leftovers, which are fatally contaminated and awaste of collagen. This article have discussed ways of removing the chromiumin the leftovers and tannery regeneration by recycling the Cr-removing liquidin tanning.A comparison has been made among different ways of Cr-removing tohelp determine the conditions of acid-alkalis removing. The optimumcondition is determined under t=45℃and the original solid-liquid ratio is1/10.So the c(NaOH) is1.0%(w/v), the leftovers should be dealt for60min; thec(H2SO4) is5.0%(v/v), v(H2SO4) is40mL and what is left of the leftoversshould be dealt for40min. Recycling and concentrating of Cr-removing liquidare used to increase Cr2O3%in the liquid which is used to accomplish theretanning with ordinary chrome-tannery agent. Not only can it obtain thermalcontraction temperature of93℃, but also has certain filling effect.The removal ratio can be more than83%after acid-alkalis removing.Retanning using the recovery tanner with ordinary chrome-tannery agent isgood enough so that the leather has familiar physical appearances as the onethat is tanned using the ordinary chrome-tannery agent. And the thermalcontraction temperature will reach above90℃.Finally, the pilot process has been designed as well as the investmentbeen analyzed. Parameters of the pilot equipments have been determined.