GB297713A - Improvements in or relating to the digestion of raw materials for paper-making and other purposes - Google Patents

Abstract

297,713. Milne, S. March 26, 1927. Corrosion, preventing.-In the manufacture of products by chemical reaction between a reagent and the cell contents of a natural organized material, fibrous or otherwise, the reaction is influenced by the application thereto of an externally generated relatively high frequency electromotive force. The invention is described in connection with the digestion of raw materials such as esparto grass for paper making &c., and results in a shortening of the time required for the treatment, reduction in the quantity of reagent used, a more complete removal of the non- cellulose matter, and the suppression of unwanted reactions. In carrying out the process the transmissions from the local broadcasting station may be used, the digester being earthed through a coil which in an example bad about 25 turns. An aerial may be connected to the top of the digester through a series condenser by which tuning may be effected. The oscillating electromotive force may be provided by an accumulator of two volts, the positive and negative terminals of which are alternately connected to an insulated metal plate g, Fig. 3, around the digester through a commutator h which is rotated to give each terminal about 80 contacts with the plate g per minute, the digester being connected to earth and to a cadmium plate o immersed in the accumulator. The effect of the cadmium plate is to ensure that the varying potential of the plate g is always positive. As an alternative to this arrangement, a four or six volt accumulator may be used, the voltage on the plate being then alternately 6 and 4 or 4 and 2 volts, the negative of the battery being connected to the digester and to earth. Maintaining a positive potential on the condenser element g retards the corrosion of the vessel, pipes, &c.