System Domain 6: Paper Making Process

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The paper making process varies by mill and company, but the basic process is relatively uniform, as it has been for many years. Technology has simply made the process more efficient over time.

The first, and likely most obvious, step is to harvest the trees. In the modern process, paper mills oftentimes have their own private land where they plant and harvest trees specifically for paper. The method of harvesting has also become more efficient and healthy for the forest over time. Instead of clear-cutting forests, leaving no species to reseed the land, most foresters use selective cutting.

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Harvested trees waiting to be debarked and chipped in Grand Rapids, MN

The foresters run the harvested trees through a basic trimmer, ensuring that logs sent to the paper mills are relatively uniform and free from branches and needles/leaves. They’re then shipped to the paper mill, where the trees are debarked and chipped.

The chips are then broken down to pulp. The differences in this process can have a large effect on the surrounding community. Paper mills that boil down chips to pulp oftentimes release odorous waste air, which is harmless, but cause the connotation between paper towns and smell. However, some paper mills use chemical or other heated processes which do not release a smell.

The pulp is then washed, cleaned, bleached (depending on its purpose), and coated (also depending on purpose, e.g. newspaper vs. magazine paper). The pulp travels along a wire screen, creating a pulp web, which is squeezed between rollers to finish draining water and create uniform sheets. This process, which is performed in PM, or paper making, machines differs between mills and even individual machines within mills. The Fourdrinier process utilizes a single-sheet process moving along a sort-of conveyor belt, while the gap former process utilizes the gap between two sheets moving in the same direction to create a more efficient type of squeezing and heating.

The semi-dry web is then heated, sometimes during the paper making process (like in the gap former machine), then rolled in large sheets before being cut down to smaller rolls. The smaller rolls are either sent off for consumption or to a printer. Then it is consumed.

Consumed paper is sometimes recycled. The recycled paper that is eligible for the paper making process is oftentimes broken down like the wooden chips to form a pulp and mixed in with wood pulp to create new paper. The percentage indication of recycled material in paper shows how much of the pulp was from recycled material and how much was from freshly-pulped wood.

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