GB663917A - Improvements in and relating to the manufacture of straw pulp - Google Patents

Abstract

Straw from barley, wheat, rye and oats, &c. is shredded longitudinally into fine strands, chemically treated at about 100 DEG C., e.g. for 8 to 12 hours, and agitated to produce high-quality pulp. The straw is shredded preferably in a moist condition, containing, e.g. 20 per cent by weight of water. The shreds may first be soaked with an aqueous solution or fine suspension of the chemical and then cooked by applying low-pressure steam for 3-5 hours. The pulp may be washed with water before being agitated. The chemical may be an alkali such as caustic soda, lime, sodium carbonate, potassium carbonate or mixture thereof or sodium sulphite, bisulphite or sulphide. A solution containing 1000-1300 gallons water and 200-250 lb. caustic soda or 150 lb. caustic soda and 100 lb. lime may be used for each ton of straw. The straw may be shredded into strands not more than 2 inches long in a machine having two or more rotatable spiked drums surrounded by a casing carrying spikes which intermesh with those on the drums. The pulp may be agitated in a similar machine having only one drum. The Provisional Specification also describes kneading of the pulp in a machine having two longitudinally-channelled rollers which mesh loosely and are mounted in a helically-ribbed casing.