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Full Version: in that training i knew how paper and pulp manufactured in industry level and what ar
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in that training i knew how paper and pulp manufactured in industry level and what are the various types of raw materials used for different types of paper
The US paper industry leads the world with more than 24 percent of global paper production capacity (American Forest and Paper Association, 1998a). It produces 9 million tons of pulp each year (US Environmental Protection Agency, 1997a). The pulp and paper industry is the most capital intensive in the United States, spending approximately $ 130,000 per employee each year on plant and equipment. Economies of scale are therefore fundamental to profitability. Pulp and paper mills produce up to 5,000 tonnes of paper per day to meet a national consumption rate of 700 pounds per year per year, twice the 1960 consumption1 (Blum et al., 1997).

Paper and cardboard products are made of pulp. The pulp is made predominantly from wood, but in many cases is made from other plant fibers such as cotton, flax, hemp and herbs such as straw, wheat, and kenaf. More recently, recycled paper has become a common material input. In 1996, US paper mills recovered 44.8 percent of the US post-consumer paper, and the industry has set a 50 percent paper recovery target for 2000 (American Forest and Paper Association, 1998b).

It is thought that papermaking originated in China in approximately 100 A.D. using rags, hemp and grass as raw material, and beating against stone mortars as the original process of fiber separation. Although mechanization increased in the intervening years, batch production methods and agricultural fiber sources remained in use until the 1800s. Continuous papermaking machines were patented at the beginning of that century. Between 1844 and 1884, wood pulp methods were developed, a source of fiber more abundant than rags and grasses, and included mechanical abrasion, as well as the chemical methods of soda, sulphite and kraft. These changes initiated the modern era of pulp and paper manufacture.

Figure 72.1 illustrates the main processes of pulp and paper manufacture in the current era: mechanical pulp; chemical pulp; repulping used paper; paper manufacture; and conversion. The industry today can be divided into two main sectors according to the types of products manufactured. The pulp is generally made in large mills in the same regions as the harvesting of fibers (ie mainly forest regions). Most of these factories also manufacture paper - for example, newsprint, writing, printing or tissue paper; or they can make cartons. (Figure 72.2 shows a mill producing bleached kraft pulp, thermomechanical pulp and newsprint.) Note the yard and rail dock for shipping, chip storage area, chip conveyors leading to the digester , to recovery boiler (high white building). Separate conversion operations are usually located near consumer markets and use market pulp or paper to make bags, cartons, containers, tissues, wrapping papers, decorative materials, commercial products, etc.

Figure 72.1 Illustration of process flow in pulp and paper manufacturing operations:

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