制浆造纸专业单词.docVIP

Chpater 8 Preparation of Papermaking Stock Stock preparation is the interface between the pulp mill or pulp warehouse and the paper machine.In an integrated mill,stock preparation begins with dilution of the heavy stock at the?discharge of the high-density pulp storage chests and ends with the blended papermaking furnish in the machine chest .In the independent paper mill ,stock preparation begins by feeding pulp bales into the repulping systerm. The basic objectives in stock preparation are to take the required fibrous raw materials (pulps) and non-fibrous components (additives), treat and modify each furnish constituent as required ,and then combine all the ingredients continuously and uniformly into the papermaking stock .The primary concern is to produce a uniform papermaking furnish to ensure stable paper machine operation and a high standard of paper quality .The following operations are usually involved. Pulping . Baled pulp (or other fibrous raw material ) is dispersed into water to form a slush or slurry. The operation can be either batch or continuous. Refining (or Beating ). The fibers are subjected to mechanical action to develop their optimal papermaking properties with respect to the product being made. The operation is usually continuous, but some non-wood and specialty pulp are still treated batch-wise. Utilization of Wet-End Additives. A wide variety of mineral and chemical agents are added to the stock, either to impart specific properties to the paper product or to facilitate the papermaking process. Preparation is usually carried but batch-wise. Metering and Blending .The various fibrous and non-fibrous furnish components are continuously combined and blended to form the papermaking stock . Additional operations may be carried out as pan of stock preparation depending on the particular system requirements .For example .pulp screening and cleaning may be necessary for some high-quality furnishes . It should be noted that the paper machi