Pulping refers to the process that uses chemical, mechanical or chemical-mechanical ways to remove the unnecessary impurities in the fiber materials. Generally, the paper pulping process can be classified into pulp cooking, pulp washing, and pulp bleaching.
There are three types of the pulping manufacturing process which are chemical pulp, mechanical pulp and chemi-mechanical pulp.
Chemical Pulp
The chemical pulp is the most widely used pulping way in the paper and pulp making. Sulfate pulp and sulfite pulp are two typical types of chemical pulp.
sulfate pulp: sulfate pulp can apply for water-absorbing products manufacture, it also used to process the paper or paper board with high tensile strength, tearing strength, burst strength.
sulfite pulp: sulfite pulp is a kind of chemical pulp made by sulfite process. It is clean and soft, easy to bleach. According to the process, sulfite pulp can be applied to manufacture the artificial fiber, writing paper, print paper, grease-proof paper and glazed transparent paper.
Mechanical Pulp
Mechanical wood pulp also known as ground wood pulp, it plays vital role in the paper and pulp indstry. Mechanical pulp is obtained by grindingfiber material with mechanical means. The mechanical wood pulp has high content of lignin, short fiber makes it fragile. Mechanical pulp is usually used with chemical pulp together to manufacture paper like news paper.
Chemi-Mechanical
Chemi-mechanical wood pulp made by grinding wood chips, shavings into fibers with grinder. For understanding the fiber, formally add a little chemicals in the preprocesing or pulp processing.
How Trees Can Become Paper?
The secret of how trees can become paper is in the fibers. When the fibers of certain plants are softened, separated, and combined with water, they become pliable. Allowing them to be beaten and flattened into a mat that can be made into and used as paper.
History: This technique originated in China in 105 AD. The art of paper-making eventually spread to North America in the 1800s. This mechanical method of physically beating the material to release the fibers was eventually replaced with a mechanical process to separate the fibers.
The craft process, invented in Germany in the late 1800s, is a chemical method for wood pulp production. The name comes from the German word craft, meaning strong. In this method, chemicals are mixed with hot water to loosen and separate the wood fibers. Both softwood and hardwood trees may be used in the paper-making process.
After trees are harvested from the woods, they’re loaded onto trucks and delivered to a paper mill. Once the bark is removed, the trees are chipped into small pieces. The chips are then mechanically processed to produce pulp or chemically treated to separate the fibers. Based on the type of paper being produced, softwood fibers, hardwood fibers, or a combination of the two may be used.
Difference Softwood and hardwood pulp
Softwood trees produce long pulp fibers which add strength. Softwood pulp is primarily used for paper intended for packaging, where the strength of the containers is important.
Hardwood trees have shorter fibers, which contribute to the smoothness of the paper. Making it ideal for paper grades intended for printing purposes. Pulp manufactured directly from the tree chips is termed virgin fiber.
Fibers obtained from processing recycled paper may also be used to produce paper products. These recycled fibers may be reused several times, but will eventually break down and become too weak for reuse.
Nationwide, the paper industry recovers almost 67% of all paper consumed. As a result, the use of recycled fiber is common throughout the industry. In addition to providing fiber for making paper, recycling diverts the paper out of the waste stream and conserves landfill space.
Please see the following attachment if you wanted to see a video of how paper product is been produced and recycled:
https://www.britannica.com/video/213166/Overiew-papermaking-process-lumber- industry
Want to know more about Canadian pulp and paper mills please read the following article below:
Sources
Comparison of Chemical Pulp, Mechanical Pulp, and Chemi-mechanical Pulp. (April 24th, 2018). Medium. Retrieved from: https://medium.com/@paperpulpingmachine/comparison-of-chemical-pulp-mechanical-pulp-and-chemi-mechanical-pulp-7b32211e0fdf
Learn in-depth the process of how paper products are produced and recycled. (2020). Britannica. Retrieved from: https://www.britannica.com/video/213166/Overiew-papermaking-process-lumber-industry
Natural Resource Canada. (n,d). Benchmarking Energy Use In Canadian Pulp and Paper Mills. Retrieved December 8th, 2020 from https://www.nrcan.gc.ca/sites/www.nrcan.gc.ca/files/oee/pdf/industrial/technical-info/benchmarking/pulp-paper/pdf/benchmark-pulp-paper-e.pdf