GB763823A - Method for treating a fibrous material - Google Patents

Abstract

<PICT:0763823/IV(b)/1> <PICT:0763823/IV(b)/2> Material such as wood pulp, bagasse, ramie, linen, or cotton, in fibre bundles, is fed through a port 17, Fig. 1, on to a rapidly rotating circular head 57 mounting an annular plate 66 having a series of triangular teeth 72, Fig. 2, co-operating with similar teeth on a plate 68 fixed to an upper casing 11. The spindle 28, which is driven by a pulley 78, is mounted in a sleeve 29, which may be moved axially by means of a hand operated worm 55 turning a wheel 49 which rotates an axially fixed nut 46 having threads engaging outer threads on a non-rotatable axially movable sleeve 35. The sleeve 35 acts on the sleeve 29 through a spring 39, so that movement up or down of the sleeve 29 varies the gaps between the co-operating teeth on the plates 66, 68 and allows these plates to separate sufficiently to pass any foreign object entering the machine. In operation, the fibre is directed by fins 64 to the teeth, and air is drawn in through the port 17. The teeth flex and separate the fibres as the fibres move to the rims of the plates, and at a specified radial distance from the point of entry of the fibre, where the separation is complete, a gas or liquid treating agent, e.g. bleaching liquid, which may be atomized before entering or in the machine, is introduced through one or more pipes 73. Substances which are sensitive to oxygen can be treated in the zone in an atmosphere of nitrogen or carbon dioxide, and steam or heated gas can be introduced to control the treating temperature. After shredding and treatment the fibres are impelled by blades 65 to an exit port 18. In one example, ground wood pulp containing 40 per cent of fibre on a dry basis is fed continuously into the apparatus and bleached with an aqueous solution containing hydrogen peroxide and sodium silicate at 75 DEG F. The treated pulp has a fibre content of 34.4 per cent on a dry basis and a pH value of between 9.5 and 10. In another example, ground wood pulp containing 38 per cent of fibre on a dry basis is fed into the apparatus with an aqueous bleaching solution containing magnesium sulphate, sodium silicate, hydrogen peroxide and sodium peroxide, the temperature of both pulp and bleach being about 140 DEG F. The pulp discharged has a pH of 9.5-10 and an increased brightness. In a further example, a sulphite pulp having a consistency of 40 per cent is treated with an aqueous solution of sodium chlorite, and the treated pulp is then stored for three hours at 104 DEG F. The pulp may be treated with both sodium chlorite and sodium hypochlorite solutions, the former being introduced nearer the point of entry of the pulp than the latter. Specification 722,820 [Group II] is referred to.ALSO:The apparatus of this Specification is identical with that described in Specification 722,820 but the claims differ and additional processes are described (see Groups IV(c) and VI).