Wood pulp is the most common material used to make paper. The timber resources used to make wood pulp are referred to as pulpwood. Wood pulp generally comes from softwood trees such as spruce, pine, fir, larch and hemlock, but also some hardwoods such as eucalyptus and birch. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ International Paper CompanyThe largest employer in Georgetown County, South CarolinaMaking paper from wood pulp ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Wood pulp is made in several stages: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ - First the bark is removed from the wood. This can be done with or without water (wet stripping). The bark is generally recovered to use as fuel in the pulp and paper making process.
- The cellulose fibres that keep the wood together are then separated. This can be done in a number of ways:
- * The wood can be crushed with grinders (huge grindstones) and then soaked in water to produce groundwood (GW). Mechanical pulps are used for products that require less strength, such as newsprint and paperboards.
- * The wood can be crushed with refiners using steam at high pressures and temperatures to produce thermomechanical pulp (TMP). TMP differs in quality from groundwood.
- * In additional to the refiners, chemicals can be used to break up the cellulose fibres. Pulp produced this way is known as chemithermomechanical pulp (CTMP). GW, TMP and CTMP are all considered as mechanical pulps. The mechanical pulps tend to turn yellow in time, because of the binding material, lignin, in the pulp.
- * Chemical pulp is produced by combining wood chips and chemicals in huge vats known as digesters. The effect of the heat and the chemicals dissolves the lignin, that binds the cellulose fibers together, without breaking the wood fibres. The fluid that contains lignin and other dissolved material is then dried and used as fuel. Chemical pulp is used for materials that need to be stronger or combined with mechanical pulps to give a product different characteristics. Chemical pulps include kraft pulp (or sulphate pulp).
- * Pulp can also be made out of waste paper and paperboard. Recycled pulp is most often used to make paperboard, newsprint or sanitary paper.
- * Research is under way to develop biological pulping, similar to chemical pulping but using certain species of fungi that are able to break down the unwanted lignin, but not the cellulose fibres. This could have major environmental benefits in reducing the pollution associated with chemical pulping.
- The pulp produced up to this point in the process can be bleached to produce a white paper product. The chemicals used to bleach pulp have been a source of environmental concern, and recently the pulp industry has been using alternatives to chlorine, such as oxygen, ozone and hydrogen peroxide.
- The pulp mixture is now sent to the paper machine, where it is shaped and dried.
Paper: Paper is a thin, flat material produced by the compression of fibres. The fibres used are usually natural and based upon cellulose. The most common material is wood pulp from pulpwood (largely softwood) trees such as spruces, but other vegetable fibre materials including cotton, linen, and hemp may ... Wood: :This article describes the material produced by trees. For other uses, see Wood (disambiguation).... Pulpwood: Pulpwood refers to timber stocks that are cut in order to make wood pulp for paper production. In the logging of mixed forest stands, the better trees usually are used for sawlogs for lumber production, while the inferior trees and components are harvested for pulpwood production. However, because...
Wood pulp related Images and Photos (experimental) | 
