GB419484A - Improvements in a porous heat insulating body - Google Patents

Abstract

419,484. Porous heat-insulating compositions; centrifugal moulding-machines. THURSTON, A. P., 329, High Holborn, London.-(Babcock & Wilcox Co. ; 85, Liberty Street, New York, U.S.A.) Nov. 20, 1933, No. 32307. [Classes 70 and 87 (ii).] A highly aerated liquid mixture comprising a refractory material and a combustible organic material is moulded and deliquidized while preserving its aerated condition and is then burnt to eliminate the organic particles. Suitable mixtures are (1) 40 parts of kaolin, 20 parts of grog, and 40 parts of wood flour ; (2) 60 parts of infusorial earth and 40 parts of wood flour. The burning is effected firstly in a reducing atmosphere up to about 1150‹ C. and finally in an oxidizing atmosphere up to 1650-1690‹ C. The blocks may be partly shielded in the kiln so that one portion acquires a dense vitrified structure while another portion retains its high porosity. Centrifugal moulding-machines for simultaneously moulding and deliquidizing the mixture comprise a rotary table 18 (Fig. 1) carrying moulds B. Each mould has a centrifugally operated follower 64 (Fig. 7) for compressing the contents, the centrifugal action being opposed by a spring 73-which withdraws the follower when the table ceases to rotate. The moulds are emptied by the operation of a piston 111 situated beneath the table 18. This raises the bottom 51 of the mould box to the level of the top of the side frame 49, and the foraminous sides 63 of the mould which are hinged at 62 to the bottom fall outwards when this position is reached to facilitate the removal of the block. Means are provided for locking the table in positions in which the moulds register with the mould-opening means.