As a major producer and consumer of paper and paperboard, before the 1990s, straw pulp accounted for more than 85% of China's papermaking raw materials. However, due to the serious pollution of the black liquor produced by straw pulp, it was difficult to control. In 2003, The country began to restrict the production of straw pulp. Grass pulp production enterprises were all shut down. The required gap can only be compensated by the import of wood pulp and waste paper. According to the statistics of the Provincial Paper Industry Association, as of now, the province has closed more than 120 enterprises and eliminated 1,800,000 tons of backward production capacity, resulting in a deficit of more than 1.5 million tons of pulp in the province.
Raw material and environmental protection pulping technology uses straw as raw material to produce paper pulp. After passing through four presses and a centrifuge, it is separated into primary color cleaning pulp, serum and solids after two technical treatments. The clean pulp is directly bleached into the papermaking process after being environmentally-friendly bleached, and no middle-stage sewage is produced. The clear liquid is recycled back to the pulping through the pipeline; the solids are collected and processed into high-strength corrugated paper reinforcement by special equipment.
The raw material and environmental protection pulping technology breaks through the end-intervention idea of ​​“generating black liquor before it is studiedâ€, but from the characteristics of the straw, the pollution control and the pulping process are carried out synchronously, so that the black liquor extraction rate in the straw is achieved. More than 99%, to achieve the separation of the original color cleaning pulp can be directly into the paper process. The black liquor is separated from the reusable supernatant and reusable lignin solids after a specially tailored precipitin treatment. This new pulping process achieved zero black liquor, zero wastewater, and zero solid waste emissions. It is estimated that due to the reuse of pulp slurry, the clean water consumption of the ton pulp is controlled within 15 tons, and the production water consumption is only 1/16 of the national standard; and the high-strength corrugated paper produced by the lignin solids produced by the ton pulp can also bring economic benefits of 700 yuan.
This technology has successfully solved the problem of black liquor pollution in straw pulping, a world problem that has plagued the papermaking industry, and is of great significance in achieving technology upgrading and sustainable development of the non-wood raw material pulp and paper industry in China. This technology can be widely applied to non-wood fiber raw materials including wheat straw, rice straw, reed, bamboo, hemp, bagasse, short fiber, etc. "It will be of great significance to break through the bottleneck of supply of raw materials in China's papermaking industry and get rid of the situation of foreign imports of wood pulp.