Patent GB-404306-A (GB)
Title: Improvements in the manufacture of porous bodies comprising refractory granules and a ceramic bond
IPC: C04B33/02
Filed: 1932-04-04
Abstract: Porous bodies, composed of highly refractory grains and a ceramic bond, are made by mixing grains of selected size with a bond, containing a higher proportion of slip clay or similar fluxing material than ball clay or similar refractory clay, causing the mixture to occupy a definite volume such that the fired article will have predetermined volume percentages of grains, bond and pores, and firing at from 1250 DEG  C. to 1300 DEG  C. so as to cause the bond to coat the grains, leaving the pores substantially open.  The refractory grains may be of silicon carbide or of crystalline alumina, for example corundum, emery or produced as described in Specification 113,960, [Class 70, Indiarubber &c.].  The bond may be composed of ball clay, slip clay and felspar within the range of the following percentages:--ball clay, 20 to 50 per cent, slip clay 30 to 75 per cent, and felspar 0 to 30 per cent.  The mixture of refractory grains and bond may contain from 5 to 40 per cent of bond.  The refractory grains are preferably "mulled," that is, they have had their sharp corners removed.  The permeability of the product may be varied by using grains of different size.  The refractory grains and bond are mixed dry and a small quantity of water is then added to give coherence until the bond has been hardened. For this purpose a small quantity of an organic binder, such as dextrine, may also be added.  The porous body is given a predetermined volume structure as described in Specification 385,328, [Group V].  The porous bodies may be used as filters, diaphragms and diffusion devices for various biological, chemical, metallurgical and electrochemical processes.ALSO:Porous bodies, composed of highly refractory grains and a ceramic bond, are made by mixing grains of selected size with a bond, containing a higher proportion of slip clay or similar fluxing material than ball clay or similar refractory clay, causing the mixture to occupy a definite volume such that the fired article will have predetermined volume percentages of grains, bond and pores, and firing at from 1250 DEG  C. to 1300 DEG  C. so as to cause the bond to coat the grains, leaving the pores substantially open.  The refractory grains may be of silicon carbide or of crystalline alumina, for example corundum, emery or produced as described in Specification 113,960, [Class 70, Indiarubber &c.].  The bond may be composed of ball clay, slip clay and felspar within the range of the following percentages:-ball clay 20 to 50 per cent, slip clay 30 to 75 per cent, and felspar 0 to 30 per cent.  The mixture of refractory grains and bond may contain from 5 to 40 per cent of bond.  The refractory grains are preferably "mulled," that is, they have had their sharp corners removed.  The permeability of the product may be varied by using grains of different size.  The refractory grains and bond are mixed dry and a small quantity of water is then added to give coherence until the bond has been hardened. For this purpose a small quantity of an organic binder, such as dextrine, may also be added.  The porous body is given a predetermined volume structure as described in Specification 385,328, [Group V].  The porous bodies may be used as filters, diaphragms and diffusion devices for various biological, chemical, metallurgical and electrochemical processes. They may be applied in aerating sewage sludge.ALSO:Porous bodies, composed of highly refractory grains and a ceramic bond, are made by mixing grains of selected size with a bond, containing a higher proportion of slip clay or similar fluxing material than ball clay or similar refractory clay, causing the mixture to occupy a definite volume such that the fired article will have predetermined volume percentages of grains, bond and pores, and firing at from 1250 DEG C. to 1300 DEG  C. so as to cause the bond to coat the grains, leaving the pores substantially open.  The refractory grains may be of silicon carbide or of crystalline alumina, for example corundum, emery or produced as described in Specification 113,960, [Class 70, Indiarubber &c.].  The bond may be composed of ball clay, slip clay and felspar within the range of the following percentages:-ball clay, 20 to 50 per cent, slip clay 30 to 75 per cent, and felspar 0 to 30 per cent.  The mixture of refractory grains and bond may contain from 5 to 40 per cent of bond.  The refractory grains are preferably "mulled," that is, they have had their sharp corners removed.  The permeability of the product may be varied by using grains of different size.  The refractory grains and bond are mixed dry and a small quantity of water is then added to give coherence until the bond has been hardened. For this purpose a small quantity of an organic binder, such as dextrine, may also be added.  The porous body is given a predetermined volume structure as described in Specification 385,328.  The porous bodies may be used as filters, diaphragms and diffusion devices for various biological, chemical, metallurgical and electro-chemical processes.  They may be applied in aerating sewage sludge.ALSO:Porous bodies, composed of highly refractory grains and a ceramic bond are made by mixing grains of selected size with a bond, containing a higher proportion of slip clay or similar fluxing material than ball clay or similar refractory clay, causing the mixture to occupy a definite volume such that the fired article will have predetermined volume percentages of grains, bond and pores, and firing at from 1250 DEG  C. to 1300 DEG  C. so as to cause the bond to coat the grains, leaving the pores substantially open.  The refractory grains may be of silicon carbide or of crystalline alumina, for example corundum, emery or produced as described in Specification 113,960, [Class 70, Indiarubber &c.].  The bond may be composed of ball clay, slip clay and felspar within the range of the following percentages:-ball clay, 20 to 50 per cent, slip clay 30 to 75 per cent, and felspar 0 to 30 per cent.  The mixture of refractory grains and bond may contain from 5 to 40 per cent of bond.  The refractory grains are preferably "mulled," that is, they have had their sharp corners removed.  The permeability of the product may be varied by using grains of different size.  The refractory grains and bond are mixed dry and a small quantity of water is then added to give coherence until the bond has been hardened. For this purpose a small quantity of an organic binder, such as dextrine, may also be added.  The porous body is given a predetermined volume structure as described in Specification 385,328, [Group V].  The porous bodies may be used as filters, diaphragms and diffusion devices for various biological, chemical, metallurgical and electrochemical processes.  They may be applied in aerating sewage sludge.