As an important branch of leather industry, fur industry plays an important role in national economy and supporting agriculture, rural areas and farmers. Research and investigation show that external constraints have the greatest impact on fur industry development. At present, the pollution of surface water and underground water has been very serious in some production areas of fur enterprises. The newly promulgated standard for discharge of water pollutants from leaf tanning and fur processing industries sets stricter requirements for the discharge of chromium, sulphide, ammonia nitrogen and chloride ions. Compared with the old standard, the water consumption per unit product of fur stipulated in the new standard has also been greatly reduced. It is the only way for fur industry to realize sustainable development to use cleaner production technology and promote the ecology of industrial structure.
Zhejiang Zhonghui Fur Co., Ltd. (hereinafter referred to as "Zhonghui Fur") undertakes the project of "Fur Cleaner Production Technology Innovation and Industry Promotion", which is jointly tackled by Sichuan University, Shaanxi University of Science and Technology, China Institute of Leather and Shoe Industry, Jiaxing College and other units. It is the first time to study the practice in the recycling of fur processing fluid. The application system technology integration, the successful research and development of fur soak, fatliquor, dyeing liquid recycling technology, greatly reduced the production and discharge of sewage, and made a significant increase in the utilization of various chemicals.
In recent years, the research and development of fur cleaner production technology has become the focus of industry development, but the systematic, mature and widely promoted fur cleaner production technology is few. Why can Chinese fur be successful in this field? One important reason is that the establishment of the academician expert workstation led by Academician Shibi has provided sufficient confidence support and strong technical support for the scientific research work of the company. Academician Shi Bi's "Leather Cleaning Technology" innovation team is relying on Sichuan University and the National Engineering Laboratory of Leather Cleaning Technology, a joint enterprise backbone of science and technology to create an international first-class scientific research team. Aiming at the bottleneck problem that restricts the sustainable development of the tannery industry, the team carried out multi-faceted research in the fields of innovative materials, innovative technologies of cleaner production and reuse technologies of tannery wastes to provide theoretical basis and technical support for the cleaner development of the tannery industry. At present, the team has reasonable knowledge structure, professional title structure and academic degree structure, and has strong research ability. The proportion of doctor degree is 100%. It has been engaged in the research of Leather Chemistry for a long time. It has undertaken a number of national-level research projects, and has accumulated rich experience in tanning agent development, tanning application and tanning theory. .
The research team of "Technology Innovation and Industry Promotion of Cleaner Production of Fur" systematically inspected the relationship between technical indexes and cycle times of fur pickling, tanning, retanning and dyeing liquor in the process of recycling at home and abroad, and provided reliable basis for the design of fur processing liquor recycling and recycling system. In order to achieve the goal of clean production, energy saving and emission reduction, the design scheme of operation liquid circulation and terminal treatment is improved step by step.
(1) In the rabbit skin workshop, according to the characteristics of impurities in the leaching solution, a curved grid was used to remove slag. At the same time, a new technical body was formed by combining the advantages of dissolved air flotation (DAF) and cavitation air flotation (CAF) with the gas-liquid multi-phase dissolved air pump air flotation technology (NAFC). At the same time, a process for the recycling of fur leaching acid wastewater and a matching equipment for realizing the process are provided. After a period of actual operation, the water consumption is reduced by more than 50 tons per week, the chemical oxygen demand (COD) load is reduced by 500 kg per week, the annual COD output is converted into 20 tons, and the water consumption is reduced by 2000 tons, which provides the premise for the later stage of sewage treatment load reduction. At the same time, the process saves 60% of salt and 30% of formic acid.
(2) in the sheepskin workshop, the construction and transformation of clean production line and waste water recycling system were carried out. Effective substances in chrome tanning waste liquor were determined after each recycling use. Cr2O3 content and aging were adjusted accordingly. A new type of chrome tanning cross-linking agent was used to improve the chrome absorption rate, realize the multiple recycling of chrome tanning operation liquor, minimize the dosage of chrome tanning agent and neutral salt, and reduce the discharge of chrome-containing wastewater. After several batches of industrial recycling, good results have been achieved. The annual workshop of 3 million sheepskin uses this technology to save 29 thousand tons of water and a large amount of chrome tanning agent annually. Compared with the traditional technology, the addition of chromium crosslinking agent increases the cost, but the tanning process can reduce the cost of tanning process by more than half through energy saving, water saving, emission reduction and chemical material saving. The color of the leather and wool after tanning has no change, the shrinkage temperature can completely meet the requirements, and has no effect on wool dyeing.
(3) the construction and renovation of clean production line and waste water recycling system were carried out in the fine leather workshop. The organic impurities in chrome retanning waste liquor were effectively removed by microfiltration and flocculation-microfiltration system combined with cationic and/or non-ionic polyacrylamide organic flocculant PAM flocculation and plate-frame filter press microfiltration in stages, and the stable circulation of chrome retanning waste liquor was more than 60 times (up to 100 times). It can reduce the loss of chrome tanning agent at the same time and achieve the goal of reducing the amount of chromium sludge emission. This technology saves about 24,000 tons of water annually. A large number of chrome tanning agents and other chemical materials are recycled.
(4) In the production of sheep wool leather, the degreasing waste liquor was recycled in one step, and the fatliquoring and dyeing were operated in different steps. The fatliquoring waste liquor was recycled three times.
After several years of joint research, the project has mature, advanced and feasible system technology. The technical indicators of the products have met the requirements of the national and European Union standards. The cycle of wastewater recycling has reached or exceeded the target. It has been industrialized and promoted. By December 2015, we had conquered 7 key generic technologies, formulated 2 industry standards, developed 14 new products and formed 3 new processes. 22 patents were applied, including 15 invention patents, 11 authorized patents, 3 of which were inventions. The project has achieved a total sales income of 1.143 billion yuan, a total profit of 49.53 million yuan and a total tax payment of 58.12 million yuan.
This is an ecologically friendly clean production technology for fur industry. Its popularization can solve the common problems faced by the fur industry in China, and can significantly improve the level of cleaner production and technological progress of the fur industry in China. Its popularization can not only obtain good economic benefits, but also bring enormous ecological and social benefits.