The Study On Clean Leather Vacuum Tanning Technology And Equipment

The tannery industry is one of pillar industries in national economy, which brought not only massive wealth for our county, but also more and more attention as its serious environmental pollution. Environmental pollution has become the key to determine whether the leather industry can make a sustainable development. Therefore, it is imminent to realize the clean leather production and then solve the pollution from the source.This study, aiming at increasing the absorption rate and binding rate in the products, used the vacuum technique to degas, to bulk, to soak, to dehydrate and so on. A new principle and craft of clean vacuum leather tanning technology was explored. The leather vacuum rotor drum for experiment was developed, and then the experiments of vacuum leather tanning technology were carried on, which accelerated the chemical reaction speed and reduced the pollution of chrome tanning. It is very important for the implementation of cleaner production technology and the sustainable development in the tannery industry.Base on multi-disciplinary comprehensive and overlapping, the following points were studied under the environment of vacuum:the changes in the internal structure of leather, the way that chemicals penetrating inside the leather and combining with the leather, the factor that affecting the penetration and combination. Several experiment, like parallel comparative trial experiment, move tans experiment, calmly tans experiment and the orthogonal experiment, were carried on using experiment vacuum rotor, which explored the new craft, optimized parameter, increased the chromium availability during the banning process step, enhanced the union between chromium and dermomyotome and shorten the tanning process time.The three factors and three levels orthogonal experiments were carried on. In the process of leather vacuum tanning, the factor of tanning time, amount of chromium powder, temperature, which affected shrinkage temperature, Cr2O3 in liquid waste, Cr2O3 in leather and Cr2O3 absorption rate, was studied. The experiments shown the first factor that affected the quality of leather was tanning time, the second was amount of chromium powder, and the last was temperature. Considering the shrinkage temperature and the absorption rate of Cr2O3, the best optimal technology was specified:tanning time was 310min, chromium powder was 1.32%, temperature was 40℃Taking the persimmon tannin as plants tanning agents, the comparative trial were carried on in atmospheric and vacuum environment respectively. The results shown:under the vacuum environment, the tanning process took 17 hours, but 157 hours in atmospheric environment. The leather was permeated completely and the shrinkage temperature was 80℃. At the meantime, the tanning time was substantially reduced, the appearance of leather was close to yellow and exquisiting, and the body of leather was soft.The principle scheme on cycle utilization of waste liquid was designed and the waste liquid circulation test was carried on. The waste chrome liquid can be recycled 5 times or more. The regularity of reproduce was stable. The methods reduced the environmental pollution and provided a new way to solve the pollution that puzzling leather industry.Based on experimental study, and according to the demands of mechanical effect and craft under the vacuum the leather tans, through the analysis comparison, the design proposal for rotor drum structure and the main technical parameters was fixed:workshop vacuum 2000～4000 Pa, heating temperature 25℃-40℃, the inner cylinder speed 5～30r/min. The 3D-model was completed using the Pro/E software, which can realize optimization of rotor drum and enhance rotor drum's working performance. It can make a great contribution for the updates and features improvement of tanning equipment.This study not only can be applied to the tanning process, but also has a reference value for the wet processing section of the leather. It may lead to a great change of the principle, equipment and the processing in tannery industry, and this has a very important meaning for the reduction of environmental pollution in tannery industry.