NO813232L - METHOD AND DEVICE FOR MANUFACTURING CELLULAR, GLASSY PRODUCTS - Google Patents

Description

REFERENCE TO RELATED APPLICATION

This application is a partial continuation of my US application

Serial No. 888,507, filed Mar. 29, 1978, now abandoned.

BACKGROUND OF THE INVENTION

1. The scope of the invention.

This invention relates to the production of cellular, vitreous plates or shapes where a significant part of the volume consists of gases enclosed in the cells, and particularly relates to the method and device for the production of cellular, vitreous, refractory material in prescribed forms and products from this material with lower densities than conventional brick or brick, and more impermeable.

2. Description of the technician's position.

There is a commercial manufacturer of cellular glass blocks that uses a process where crushed or pulverized glass is the main starting material. The finely grained glass powder is mixed with two chemical agents which react to form a gas at a temperature above the point at which the glass sinters to trap the gas. The same company owns US Patent No. 2,890,127 which shows the use of crushed quartzite as the charge and special carbon particles or silicon carbide, the carbon reacting with SiO2 to form the foam gas. It also owns US patent no. 2,890,126 which shows the support of the charge by graphite plates and the addition of mixtures such as feldspar, to the mixture according to patent no. 2,890,127 to reduce viscosity and improve sintering and cell formation. Commercial production was maintained, with various interruptions, for several years and then abandoned. These two patents emphasized the radically improved properties achieved when the glass blocks are of almost pure silica glass.

The furnace for the commercial process described above was made of graphite plates which acted as resistance heaters.■ The charge was carried in graphite pans which were pushed in trains through the furnace. The process was not good, as I understand it, because it was too expensive and the graphite plates and pans were not durable. My

process avoids expensive grinding down to fine-grained size and the use of expensive, high-quality graphite for furnace parts and charge pans.

Various patents describe the foaming of various minerals to avoid the expense of first making powdered glass. None have led to a continuous commercial production of a plate or shape; but Dow Chemical produced "market development" quantities of foamed glassy clay blocks for several years, using clay as raw material. The known technique of blowing clay into lumps of cellular material gave Dow the hot lumps which they pressed and thus welded into blocks. (U.S. Patent No. 3,056,184).

For centuries, prescribed shapes of roof tiles, wall tiles, floor tiles, bricks and various ceramic bodies, such as flower pots, porcelain and the like, have been produced by pressing a mixture of clay and water which is then dried and sintered. Products such as bricks have been produced by extruding clay mixtures so that. the charge is compressed into fairly dense masses. "Dry" pressing of clay mixtures at high pressure has also been widely used.

Such dense clay mixtures which have been produced by dry pressing or steam pressing have usually contained from approx. 5% to 8% moisture and has been exposed to from approx. 1000 psi to approx. 5000 psi. In the known extrusion of clay mixtures, the moisture content of the clay mixture is usually higher, namely in the vicinity of from 15% to 20%; however, very high pressures are still required.

Each of the resulting dense mixtures must be dried rather slowly over a long period of time to allow gradual migration of the moisture through the clay. If such a procedure is not followed, the clay may crack or explode during drying. The resulting sintered clay is fairly dense and maintains its original shape without cracking or dissolving. Sintering takes place at a temperature below the melting temperature of the clay used. I use a mixture that has a low moisture content and is pressed at low pressures. This enables rapid heating of the charge, which can crack during sintering, but such cracks are later repaired.

In the past, the cell formation of clay materials has been carried out. E.g. Ford showed, in US patent no. 2,485,724, that by using sintering substances (flux) low-temperature foaming of a special Albany slip clay could be carried out using an oxygen-containing agent and carbon in the form of soot. Ford also showed that urea, sugar, dextrose, or molasses could replace the soot for the manufacture of bodies with densities from 10 to 20 pounds per pound. cubic feet. The firing temperature was in the vicinity of 1500°F to 1800°F.

In my US patent no. 3,967,970, I produced an inflated clay by firing at approx. 2100°F' to 2300°F of a mixture of clay, sugar, sodium or potassium hydroxide and water. In Example 4 of this patent, I replaced the sodium hydroxide with tri-sodium phosphate.

The process according to the present invention eliminates the costs, problems and uncertainties of using sintering substances and has thus produced a foamed product with a higher melting point and better resistance to water and chemical agents.

US patent no. 2,337,672 shows the production of multicellular glass by heating a charge of glass, arsenic oxide, zinc or cadmium and coal powder to produce a reaction between the oxide and the carbon.

Less relevant US patents associated with inflation of

ceramic material includes the following:

3 174 870 3 150 988. 3 666 506 2 880 099 3 536 503 2 564 978 3 307 957 2 670 299

None of the previously known patents mentioned above. shows some practical means of making a foamed mineral block or slab quickly and economically.

Accordingly, it is an object of the present invention to provide a device and a method for producing a foamed mineral object quickly, efficiently and at low costs.

Another object of the present invention is to provide a foamed mineral object which is highly insulating and

light and yet resistant to ageing, corrosion and water absorption.

Another purpose of the present invention is to provide a method and device for producing a foamed mineral material and the material itself, which has a high material strength and is able to form load-bearing walls and roof decks with widely spaced supports and which can be produced in large plates.

Other purposes features and advantages of the present invention

will appear from the following detailed description.

SUMMARY OF THE INVENTION

Briefly described, the method of the present invention uses low pressure to compact a clay, carbonaceous material and moisture, mixing charge followed by rapid heating to dry the clay charge and the gradual firing of the shaped charge, above melting temperature, on rollers without the need for carrier plates to produce a preformed, cellular, vitreous, impermeable, lightweight, refractory material. The movement of the charge through the combustion zone is slow, but no significant deflection of the charge bands takes place, as a result of the high velocity of the molten clay used. Any cracks that occur during drying or preheating are repaired by inflating the clay.

Mainly the same method is used for the production of a preformed, foamed, fused silica product, with finely divided silica and carbonaceous foaming agent being used as a charge.

When a clay or silica tape has been treated to be passed over the device's rollers, in certain cases a release agent is used on the bottom of the tape and perhaps on the sides.

The device according to the present invention includes a number of side-by-side sets of moist pressure rollers to each of which a mixture of clay and/or shale whose carbon content and moisture content have been regulated is delivered from a hopper. Each set of rollers co-extrudes' also a release agent around the sides and bottom of the strip of clay raw material being extruded. Nozzles glaze the ribbon's upper side.

The force from the rollers feeds the strips along parallel, horizontal, vertically spaced paths into the first heating or preheating chamber of the furnace, and then into the combustion chamber along the upper surfaces of the rollers. The ends of the rollers protrude from the walls of the oven, as the end parts are supported on circumferentially distributed running wheels and can rotate at the same time with the help of a common belt.

Fuel and air are supplied, via the collection chamber, to the burners, which are arranged in a staggered relationship in opposite parallel rows along the furnace sides in the combustion chamber.

Exhaust gas openings are arranged opposite the nozzles, which openings lead to manifolds which feed to the exit part of the furnace's preheating chamber. Exhaust fans bring the exhaust gases from the entrance to the pre-heating chamber. Sintering of the strips usually takes place in the preheating chamber.

Foaming of the sintered clay ribbons takes place at above

about. 2000°F in the combustion chamber as the strips are gradually moved along the rollers in the combustion chamber.

The bands coming out of the combustion chamber exit are in shape

of impermeable, cellular streams of refractory material and is fed into an annealing-flux furnace where its temperature is rapidly reduced to annealing temperature and then annealing. These products are then fed to conveyors where they are cut into rectangular blocks.

In another embodiment of the invention, a charge of silica, carbonaceous material and water is produced in a heated low-pressure press. A plate made of aluminum foil or other release agent and a layer of pitch and coke or coal is produced on the underside of the charge, at the same time as the charge is pressed.

This compressed silica charge is fed on its plate through the furnace end to end and is preheated and foamed in the manner previously described for clay. Cellular, fused silica blocks are formed.

The third embodiment includes two-stage extruders, each having three feed rollers for feeding a charge such as a ribbon from a hopper horizontally to the furnace. The release agent is sprayed from below on the ribbon and the glaze from above. The oven according to the third embodiment has muffle plates to form vertically separated chambers above and below the bands, which chambers have exits to the oven's drying or preheating zone.

In the fourth embodiment, the furnace is designed as a shock feeder with pre-assembled pans containing loads of silica material. The pan's sections are either assembled in advance to receive a hand-stamped charge or respectively provided with pressed charges which, when melted, form a monolithic or uniformly molten product.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. IA is a schematic vertical section of an embodiment form of a device for producing cellular refractory material according to the present invention, the device being shown for the treatment of clay chargers, Fig. 1B is a continuation of the sketch of the apparatus shown

in fig. IA,

Fig. 1C is a continuation of the drawing in fig. IB,

Fig. 2 is a vertical section largely along the line 2-2

on fig. IA,

Fig. 3 is a vertical section largely along the line 3-3

on fig. IA,

Fig. 4 is a vertical section largely along the line 4-4

on fig. IB,

Fig. 5 is a vertical section largely along the line 5-5

on fig. IB,

Fig. 6 is a vertical section largely along the line 6-6

on fig. 1C,

Fig. 7 is a vertical section largely along the line 7-7

on fig. 1C,

Fig. 8 is a vertical section similar to fig. 4 of a modified form of the oven according to the present invention, Fig. 9 is a vertical section similar to fig. 5 of a modified

form of the present invention,

Fig. 10 is a vertical section of the front part of another embodiment of the present invention and shows a press unit for forming successive rectangular charges to be fed to the furnace, Fig. 11 is a section of a side view on a larger scale showing the operation for the horizontal feed rollers in the oven in fig. IA, IB and 1C, Fig..12 is a view similar to fig. 11, but shows the operation for the feed rollers which have a greater mutual distance than the rollers according to fig. 11, Fig. 13A is a vertical section similar to fig. IA but shows a third embodiment of the device for the production of cellular refractory material, Fig. 13B is a continuation of the drawing shown in fig. 13A, Fig. 13C is a continuation of the drawing shown in fig. 13B and

shows the glaze application devices and the annealing swallow furnace,

Fig. 14 is a vertical section largely along the line 14-14 in fig. 13A, Fig. 15 is a vertical section generally along the line 15-15

on fig. IA,

Fig. 16 is a vertical section largely along the line. 16-16 in fig. 13A, Fig. 17 is a vertical section generally along the line 17-17 of Fig. 13B, Fig. 18A is a vertical section similar to fig. 1A and fig. 13A, and shows a fourth embodiment of my invention,

Fig. 18B is a continuation of fig. 18A, and

Fig. 19 is an expanded perspective view of mutually adjacent sections that form a first pan for receiving an unpressed charge of sand or briquettes, Fig. 20 is an expanded perspective view of several mutually adjacent sections that form a pan, which sections are shown after they have been pressed with their respective portions of the total charge, Fig. 21 is a perspective view of the composite pan of fig. 20 without the charge, and Fig. 22 is a section of a ground plan of a part of the pan in fig. 20 and 21 with its charge in the furnace according to fig. 13A, 13B and 13C, the sides and vertical alignment rollers in the furnace being shown in cross section.

DESCRIPTION OF PREFERRED EMBODIMENTS

While referring in detail to the embodiments that have been chosen for the purpose of illustrating the device according to the present invention, the number 10 in fig. 1 a vertically arranged funnel with parallel triangular end walls 11 connected with downwardly converging side walls 12 which end in a rectangular opening at the bottom portions of the funnel. A set of wet press rollers is stored at the hopper 10 opening. This set includes a pair of opposed compression rollers 13 which are stored in brackets 14 for rotation about parallel, spaced apart, horizontally arranged axes or shafts 15 which turn in opposite directions for compressing and feeding the material or charge into the hopper 10 in a curved pipeline 16 with a rectangular cross-section. End rollers 19 which are arranged along axes or shafts perpendicular to the axes 15 cooperate with the rollers 13 for compaction and movement of the material into the pipeline 16.

The rollers 13 and 19 thus extrude a rectangular band 20 of the raw material or charge in a vertically downward path

into the upper end part of the pipeline 16. The curved contour of the pipeline 16 gradually changes the course of the belt 20 from one vertical path to another

■ a horizontal path, the lower end portion 17 of the pipeline 16 projecting in a horizontal direction outwards from the pipeline 16 to form a sliding plate along which the band 20 is gradually moved. The upper surface of the sliding plate 17 is arranged in line with the upper circumference of a number of parallel arranged infeed conveyor rollers 18 which are made either of steel or of ceramic material. The feed rollers 18 rotate synchronously so that they form a movable surface for transporting the strip 20 into the entrance opening 9 in the front or entrance end 26 of an oven which is generally indicated by the number 25. The strip 20 thus forms a continuous charge with a rectangular cross-section which is moved through the oven 25 from the inlet end 26 of the oven 25 to its outlet end 27.

As can be seen from fig. IA, the funnel 10 is divided into compartments which include a main charge receiving compartment 21 and a release medium compartment 22. A U-shaped dividing wall 23 separates the two compartments 21 and 22. In more detail, the dividing wall 23 includes opposite obtuse, triangular, downwardly converging, parallel side walls 24 which at their front edges are connected to the side walls 11. The rear edges of the side walls 24 are each connected to the edge of a transverse rectangular partition plate 26a. Thus, a U-shaped secondary or release agent compartment 22 is formed by a part of the funnel 10 and the dividing wall 23 which surrounds three sides of the main charge receiving chamber 21.

A mixture consisting of clayey material, water and carbonaceous material (adjusted for carbonaceous material and moisture) is, after being granular and thoroughly mixed, fed into the main compartment 21. A release agent is fed into compartment 22. This release agent can be any of a number of means used to prevent surfaces from sticking in a shape. In order to keep the rolls 35 and 36 clean, I prefer to use a moist mixture of fireclay and burnt and crushed fireclay which is reused which has the dual function of separating the extruded band 20 of clay-containing material from the rolls in the kiln 25 and also to limit the expansion width of the band 20 in the transverse direction. Furthermore, the release agent around the tape's 20 sides and bottom can be made sufficiently strong to resist breakage

in the case of a sticky spot on the rollers 35 and 36 caused by accidental contamination.

An alternative release agent mixture of silica sand combined with moist clay to approx. 8 to 20% clay can be used to

provide suitable bonding for substantial cohesion of the release layer through the blank and drying stages. This would give a stronger connection when fired, except that the sudden expansion of the sand grains at approx. 1073°F mostly breaks the bond. Then, in the case of a sticky spot of molten material on the rollers, the sand grains are discharged to the spot until the stickiness is covered.

In that case the charge is silica or clay with a melting temperature above approx. 29 00°F the release agent should be lime-bound carbonaceous material such as coke or coal.•

When a pitch- or tar-bound coke or coal is to be used as a release agent, a low-pressure rectangular press 202 in fig. 10 where the plate 203 of the press 202 receives the release agent as a first layer and the clay or silica charge is placed over this.

In more detail, the press 202 includes a vertically arranged, double-acting hydraulic or pneumatic cylinder 204 whose piston rod reciprocates (moves back and forth) a rectangular, flat metal press plate 205 in a vertical path.

The heated rectangular plate 203 is arranged in a fixed position in registration under the plate 205. Under the plate 203 is a vertically movable edge support plate 206 which carries an upright edge element 207 which surrounds the edge portions of the plate 203. Legs 208 projecting through holes in the support plate 206 carry the plate 203.

A jack 209 reciprocates the plate 206 and thus the edge element 207 in a vertical path from the position shown with broken lines to the position shown with solid lines in fig. 10.

Mounted for horizontal movement above plate 203 is a jack plate 211 which is carried by the piston rod of a horizontally arranged jack 213. A sliding plate 213 on the side of plate 203 forms a deck over which successive chargers 220 are fed from

press 202 into furnace 225 for processing.

During operation, the plate 205 is pulled back and the edge element 207 is raised around the plate 206. The charge, which can consist of an aluminum plate, a carbonaceous material and a binder on the plate as a thin layer, and the silica charge above this, is placed in the edge element 207 on the plate 203. The material is then pressed using the plate 205 via activation of the press cylinder 204

and then the plate 205 is withdrawn. The edge element 207 is then pulled downwards and the jack 213 is activated to move the jack plate 211 over the plate 203 and force the charge 220 into the furnace 225. Successive chargers 220 form a band which enters the furnace 225 where it is then processed in the same way as the band 20 in oven 2 5.

The low-pressure press 202 is normally used to exert a pressure of approx. 50 psi to approx. 1000 psi and can be used instead of rollers 13 and 19 for forming clay chargers with or without a release agent along the bottom surface or the bottom and side surfaces of the clay charge.

Arranged above the sliding plate 17 is a heating device 28 whose task is to dry the upper surface of the belt 20 as it comes out of the pipeline 16 in a horizontal path. The heating device 28 may, if desired, be an electric resistance element or a gas heating device or any heating device which can supply sufficient heat to simply dry the upper surface of the tape 20. Behind the heating device 28, along the path of the band 20, a color coating nozzle device 29 is arranged which extends across the path of the band 20. The task of this nozzle device 29 is to feed glaze onto the upper surface of the tape 20 after the surface has been dried. The color coating can of course be omitted if not desired.

At this stage, the strip 20 is thus advanced in a horizontal path and has a release agent along its bottom and side surfaces and with glaze along its upper surface. A second hopper 110 identical to the hopper 10 is arranged near the hopper 10 to provide another band 120 for inlet to the furnace 25. This second hopper 110 includes rectangular downwardly converging side walls 112 and truncated triangular walls 111 forming a rectangular downwardly converging funnel. The hopper 110 also includes opposing feed rollers 112 which rotate on shafts 115 and are supported in brackets 114. Furthermore, the hopper 110 includes side rollers 119 which cooperate with the feed rollers 113 in forming a downward stream or band 120 which is received in the curved pipeline 116. The pipeline 116 gradually changes the path of the belt 120 from a vertically downward path to a horizontally directed path. Like the funnel 10, the funnel 110 includes a partition wall 123 so that the band 120 is equipped with a release agent along its bottom surface and side surfaces. Furthermore, the upper side of the belt 120 as the belt emerges in a horizontal path is supported by a sliding plate 117 and is heated by a heating device 128 near its upper side. A glaze application nozzle unit 129 is arranged for spraying glaze onto the warm and dried upper side of the ribbon 120. The belt 120 is then fed into the furnace 25 through a rectangular opening or port 109 arranged vertically at a distance above the rectangular entrance port 9 for the belt 20. The belts 20 and 120 are thus arranged and run through the furnace 25 from the input end 26 to the output end 27 along parallel , horizontal, vertically spaced running lanes.

Explained in more detail, the oven 25 or at least the oven's lining is made of refractory material. It is generally rectangular in shape over its entire length. In the middle part of the oven 25 is a vertical partition 30 which separates the inside of the oven 25 into a drying and preheating chamber 31 and a combustion chamber 32. In other words, the chambers 31 and 32 are arranged one after the other along the longitudinal movement path of the belts 20 and 120. The partition wall 30 has two vertically separated openings or ports 30a and 130a through which the bands 20 and

120 passes. Ports 9, 30a and 60 are arranged horizontally in line, while 109, 130a and 160 are arranged horizontally in line above ports 9, 30a and 60.

All burners 40 that heat the oven 25 are preferably in the combustion chamber 32, as the drying and preheating chamber 31 receives the exhaust gases from the combustion chamber 32.

As stated above, the oven is 25 and especially the combustion zone or

-chamber 32, made of or lined with refractory material capable of withstanding temperatures near 2300°F and up to 3300°F in some cases. The chamber 31 is less critical in that it always has a lower temperature than the chamber 32, but refractory material should be used for lining this chamber 31. The rollers 35 and 135 in the preheating chamber 31 and the rollers 36 and 136 in the combustion chamber 32

is of suitable refractory material, such as high alumina or fused silica. The rollers 35 and 36 are arranged along a horizontal path and extend across the furnace 25, the ends of the rollers 35 and 36 projecting through suitable holes in opposite inner walls 37 and 38 and outer walls of the furnace 25.

The upper circumferences of the rollers 35 and the upper circumferences of the rollers 36

is arranged along a common horizontal plane and is arranged to receive and support the band 20 at its lower surface.

In the same way, the rollers 135 and 136 project through suitable holes in the side walls 37 and 38 and form upper circumferences which are in a common plane and receive the underside of the belt 120 for supporting the same. The planes 135 and 136 of the rollers are parallel to and located above the planes 35 and 36 of the rollers.

Although I have used an oven 25 with two paths of movement for the raw material or belts 20 and 120 through the oven 25 fed by rollers 13, 19, 18, 113 and 119 respectively, the number of streams of raw material can be increased as desired by duplicating those shown here systems. Thus, further lines of hoppers 10, 110, rollers 13, 113, 15, 115 etc. and a corresponding number of rollers 35, 36 and 135, 136 can be undesirably used in a single oven.

As a means of heating the combustion chamber 32, I have provided a number of spaced laterally directed fuel, i.e. oil or gas, combustion nozzles or burners 40 projecting through the walls 38 forming the chamber 32. The nozzles 40 on one side of the chamber 32 is offset in relation to the nozzles 40 on the other side wall 38 of the chamber 32. Furthermore, there are horizontal rows of thus offset nozzles 40 below the row of rollers 36 and between the row of rollers 36 and the rollers 136, and between the roof 41 and the row of rollers. 136. Flames from the nozzles 40 are thus introduced laterally in alternating directions above and below the bands 20

and 120.

Across from each nozzle 40, the gas outflow ports 42 are formed in the side walls 38. The outflow ports 42 are thus arranged in horizontal rows corresponding to the rows of nozzles 40

and is also arranged offset in relation to the transversely arranged ports 42. It now appears that each side wall 38 has three vertically separated rows where there is alternately an outflow port 42 and a nozzle 40 with the same mutual distance in the longitudinal direction. Each nozzle 40 directs its flame across the burning

the chamber 32 so that a substantial part of the exhaust gases flows through the opposite port 42 and out of the chamber 32.

With the nozzles 40 in a mutually staggered relationship in the transverse direction in each horizontal row, rotating gas flows are formed alternately clockwise and counter-clockwise above and below the bands 20 and 120.

Each nozzle 40 is arranged with a regular distance in the longitudinal direction between two adjacent rollers 36 and 136 and projects through and is supported by the side wall 38. Combustion gas, such as natural gas, is supplied from a gas collection container 43 through single branch lines 43a to the nozzles 40. An air collection container 47 supplies air under pressure through lines 44a as air supply for mixing with the gas at the nozzles 40. The collection containers 4 3 and 44 are arranged on opposite sides 48 of the combustion chamber 32. A similar arrangement can be used for fuel oil or other fuel.

As can best be seen from fig. 5, the furnace 25 is provided with outer walls 44 which are arranged outside and parallel to the inner side walls 38. Upper and lower horizontal walls 45 and 46 connect the upper and lower edges of the walls 44 with their respective inner side walls 38 to form horizontally extending channels 47 on opposite sides of the inner side walls 37. End walls 56

which are parallel to the rear end wall 27 close the downstream end of the channels 47.

The walls 44, 45, 46 delimit manifolds which enclose all the exhaust ports 4 2 so that they communicate, on their respective sides, with the horizontally extending channels 47. Mutually separated blocks 57 under the walls 46 form support for these manifolds.

The walls 44, 45, 46 extend in an upstream direction across the opposite side walls 37 of the upstream end portion of the chamber 31 to end at the end wall 58. Opposite, vertically separated exhaust gas inlet ports .59 are arranged in the side walls 37 end portions as shown in fig. IB, so that they communicate with the channels 47 as best shown in fig. 4. The channels 47 thus conduct all the exhaust gases from the combustion chamber 32 and introduce them laterally through ports 59 on opposite sides of the chamber 31 both above and below the bands 20 and 120 in the chamber 31 downstream and such gases flow in an upstream direction, as indicated by the arrows, as they are occupied by outflow ports 48 arranged in the walls 37 near the chamber 31

front- 26 or entrance end.

The transversely opposed outflow ports 48 communicate with opposite, upwardly extending suction channels 55 which communicate with exhaust gas manifolds 49 arranged on the outside of the furnace 25 near the walls 37. These exhaust gas manifolds 49 lead upwards into an intake channel 50 which is connected to the intake ports of a exhaust fan 51 which is driven by a motor 52 via belt 53. The fan 51 delivers through a chimney 54 to the atmosphere.

Individual controls for the nozzles 40 including strategically located pyrometers and valves (not shown) which enable an operator to control the combustion chamber 32 transverse heating zones so that the heat in the combustion chamber 32 can be maintained within fairly tight tolerances. These cross-flowing gases, both above and below the conveyor belts 20 and 120, make it possible to keep the combustion chamber 3.2 at a suitable temperature for the gradual burning and foaming or cell formation of successive parts of the clay strips 20 and 120, as they are advanced along the combustion chamber 32. Air /fuel ratio is maintained in different zones, as desired, at oxidizing, neutral, or reducing value.

The cellular or expanded, glassy clay, denoted by the numbers 20a and 120a, thus gradually and continuously comes out through outlet ports 60 and 160 at the rear end 27 of rollers 61, 161.

When the cellular glassy clay ribbons 20a and 120a emerge from the kiln 25, their upper surfaces may be undesirably treated with additional surface material, such as a dry granular fritted glaze 62. The glaze or coating material 62 is held in a hopper 63 near one side of the kiln 25. The bottom portion of the hopper 63 is equipped with a transverse, hollow, distribution cylinder 65 which carries a horizontally arranged screw conveyor 64. The distribution cylinder 65 communicates at one end with the funnel 63 and is provided on its lower side with a number of axially distributed holes 66.

As the cylinder 65 will be exposed to very strong heat, it is arranged across the upper part of the movement path of the expanded or inflated clay band 20a, as a device for cooling both the coating material 62 and the cylinder or trough 65 is arranged. This cooling device includes a hollow central shaft 67 for the conveyor 64 through which water under pressure is led. The shaft 67 and the screw conveyor 64. which are attached to the shaft 67 are rotated by means of a motor 68 and chain drive 69. Water is fed to the shaft 67 by means of a pump 70 through a pipe 71, shaft 167, pipes 72 and 73 from a tank 74 A return line 75 delivers the cooling water back to the tank 74.

The shaft 167 is identical to the shaft 67 and carries a screw conveyor 64 in a cylinder or trough 165 to a hopper 163 which is driven by a motor 168 and chain 169 for feeding fritted glaze 162 through hole 166 on the upper side of the belt 120a. The cylinder 165 extends across the band 120a.

Outlet pipes 76 and 176 at the ends of the cylinders 66, 166 feed any excess fritted glaze 62 or 162 to containers 77, 177.

By selective operation of the motors 68, 168, fritted glaze 62, 162 is delivered to the hot upper sides of the belts 20a, 120a. The glaze melts immediately to form a glazed surface on the ribbons.

As indicated above, the end portions of the rollers 35, 36, 135, 136 protrude through suitable holes in the walls 37, 38, 44, 237, 238, 244 of the furnace 25 and 225. As shown in fig. 12 can e.g. the rollers 35, which carry the charge before sintering and are in the drying and preheating chamber 31, arranged at a distance from each other with a greater distance than the mutual distance between the rollers 36. With such a greater mutual distance, each end part of the rollers 35 outside the furnace is limited by three circumferential distributed impellers 70a, 70b, 70c. The impellers 70a, 70b, 70c are supported for rotation by means of axle pins 71 which project into the outer walls 44. The axis of each lowermost wheel 70c is vertically below the roller 35 which it carries.

A continuous steel belt 72 running between each wheel 70c and its associated roller 35 to the next and then to the next provides synchronized operation for all the rollers 35. The same belt 72 also runs under all the rollers 36 as shown in fig. 11, being taken up between the end portion of each roller 36 and its associated wheel 73c which is underneath.

As the rollers 36 are closer together, they can share a further wheel 73b which is located between them and rests against the circumferences of the adjacent rollers 36 across the axial plane of such rollers 36. Such wheels 73b cooperate with the belt 72 for synchronized rotation of the rollers 36. The external roller 36 has an outer runner 73a circumferentially at a distance from the wheels 73b and 73c for this roller 36.

The belt 72 runs around suitable drive or guide rollers 74 outside the rollers 35 and 36. A motor (not shown) may drive the belt 72. Rollers 135, 136 have a similar operation. Swaleovn 80 is provided with a similar operation for its rollers. The drive devices can be on one or both sides of the furnace or the flue furnace to drive one or both end parts of the rollers.

At locations along the bands' 20, 120 path of movement, if

where expansion or contraction of the belts occurs, it may be found desirable to allow one or more of the rollers, such as rollers 35, 36, 135, 136, to run freely. This can be easily done by moving the relevant associated wheel(s) 70c and/or 7 3c laterally inwards or outwards so that they come out of engagement with the belt 72.

After the swollen strips 20a and 120 come out of the furnace 25 and after additional glaze 62 has been applied to the upper side of the material, if desired, the strips 20a and 120a can be fed into an annealing swallow furnace generally indicated by the number 80. The swallow furnace 80 is as the furnace 25 divided into compartments, the first of which is a cooling chamber 81 and the others annealing chambers 82a, 82b, 82c. The swallow furnace 80 includes a front wall 83, intermediate partitions 84a, 84b, 84c, 84d and a rear wall 85. It also has front side walls 86 and rear side walls 87 as well as a top 88 and a bottom 89.

Rollers 87 and 187 form horizontal conveyors for the bands 20a and 120a in the first chamber 81. Rollers 88 and 188 form horizontal conveyors in the second chamber 82. The front wall 83 is designed with ports 90 and 190 through which the respective bands 20a and 120a are introduced in the chamber 81. The partitions 84a, 84b, 84c, 84d are designed with ports such as ports 91 and 191 through which the bands 20a and 120a are led from the chamber 81 into successive chambers 82a, 82b, 82c, 82d. The back wall 85 is equipped with openings 92 and 192 through which the bands 20a and 120a come out of the swallow furnace 80.

Further transverse rollers 93 and 193 form horizontal conveyors for the cooled strips 20a and 120a which come out of the swale furnace 80.

For rapid cooling of the bands 20a, 120a in the cooling chamber 81, a compressed air circulation system 119 is arranged. Defete

system 119e includes three transverse metal guide plates 95, 96, 97 and a bottom plate 98 arranged in the chamber 81. The plate 95 was arranged above the band 120a; the plate 96 under the belt 120a and the rollers 187; plate 97 above band 20a and below plate 96; the plate 98 below the belt 20a and the rollers 87 and the plate 99 below the plate 98. The plates 96 and 97 were formed by transverse depressions and elevations to accommodate the rollers 87 and 187. The plates 95, 96, 97 and 98 are perforated or provided with holes .

Plate 95 and the top of the swallow furnace 80 thus formed an upper chamber, plates 96 and 97 a middle chamber and plates 98 and 99

a lower chamber. These chambers are connected to the outlet side of a fan 100 through a branch duct 101a and a manifold 101 so that cooling air is forced into the chambers and directed towards the upper and lower surfaces of the bands 20a and 120a as shown by arrows in<s>fig. 7.

Air flows out of the chamber 81 via channels 102 which lead from the opposite side of the swallow furnace 80 at the level of the belts 20a, 120a. These channels 102 lead to an outlet manifold 103 which communicates with a collection container 104. A common outlet channel 105 is connected to a branch channel 106 to the collection container 105.

A transverse channel 107 leads from the collection container 104 via T-piece 108a to the fan's 100th intake. The second channel 108b which is connected to the T-piece 108a has an opening to ambient air. By maneuvering the damper 108 in the T-piece 108a, the ratio between ambient air and recycled air can be regulated for cooling the belts 20a, 120a in the chamber 81.

The annealing furnace is made up of a series of chambers 82a, 82b, 82c, 82d similar to chamber 81, each having individually controlled air circulation systems 119a, 119b, 119c, 119d identical to the described system 119e. All collecting containers, such as the collecting container 104, deliver to. the common duct 105, as the heat from there is used for heating needs in the facility, or as preheated air for the burners.

After the bands 20a and 120a come out of the annealing-swivel furnace 80, they are divided in the transverse direction during their path of movement so that rectangular plates are formed. These boards have a width of the order of 4 to 8 feet, the length being cut to order. Trimming of edges, leveling of surfaces, and division into smaller parts is carried out as required. The roof can be designed with joint parts for interlocking.

Periodically along the movement path of the belts 20 and 120 and in the continuation of such belts, namely the belts 20a and 120a, there are arranged vertically arranged guide rollers 121 which are located on opposite sides of the path of the belts 20, 120, 20a, 120a for guiding the belts through the respective ovens 25 and 80.

Figures 8 and 9 show an oven 225 which is identical to oven 25 except that it has vertical guide rollers 280 and operation for these. Explained in more detail, the furnace 225 includes inner walls 238, outer walls 244, horizontal walls 245, 246, roof 241 and bottom 242 and rollers 235, 236, 335, 336 which receive and transport the bands 220 and 320 through the preheating chamber 231 and the combustion chamber 232.- Fuel is introduced into the combustion chamber 232 through nozzles 240.

As shown in fig. 8 and 9 there are a number of longitudinally separated, opposite pairs of vertically arranged guide rollers 280 in the furnace 225, which protrude between adjacent horizontal rollers 235, 236, 335, 336. The task of these rollers 280 is to guide the charges 220 and 320 in their longitudinal paths through the furnace 225. The ends of the rollers 280 project through suitable holes in the top 241 and the bottom 242 of the furnace 225. The bottom portions of the vertical rollers 280 are engaged and stored in axial bearings 281. The upper end portions of the rollers 280 extend through the bearings 282 and protrude from these.

The upper ends of the rollers 280 accommodate sprockets 283 around which runs an endless chain 284 which drives the opposite pair of rollers 280 in opposite directions with approximately the same rotational speed as the rollers 235, 236, 335, 336.

The distance between the rollers 280 is a matter of choice, but they should be sufficiently close to each other to prevent noticeable lateral movement of the charges 220 or 320. The flue furnace 80 and the furnace 25 can, if desired, be equipped with such vertical rollers as the rollers 280.

THIRD EMBODIMENT

The third embodiment shown in fig. 13A, 13B, 13C, 14, 15, 16" and 17 have multi-stage extruders formed by rectangular, vertically arranged hoppers 310 and 410 with downwardly converging side walls 312 and 412 which are connected by triangular end walls 311 and 411 and pressure rolls 313, 313a, 313b , 319, 413, 413a, 413b and 419.

The powered drive rollers 313, 313a are arranged on opposite sides of the mouth of the funnel 310 and with the end rollers 319 they compress and feed the charge as a rectangular compressed stream downwards. The shafts 315 of these rollers 313, 313a and the axis of the rollers 319 are arranged in a common horizontal plane.

The power-driven pressure rollers 313b in the second stage are arranged below the roller 313 with its axis parallel to the shafts 315 of the rollers 313, 313a. The rollers 313 and 313b cooperate to clamp and feed the charge horizontally as a stream. One

curved plate 317 concentric with the roller 313 defines an intermediate chamber. The plate 317 extends from near the inner circumference of the roller 313a to near the inner circumference of the roller 313b and acts as a control means for controlling the outer surface of the flow. The rollers 313 and 313a thus give the clay charge an initial compression whereby the flow is fed downwards and the rollers 313, 313b a second and subsequent compression which feeds the flow horizontally. Further opposing rollers (not shown) may constitute subsequent steps for cooperation with rollers 313, 313a, 313b for forming, compacting and feeding the charge as a rectangular band 320 of indefinite or continuous length which is fed horizontally onto a receiving sliding plate 317a which is arranged outside near the upper circumference of the roller 313b. From there, drive rollers 318 feed the strip 320 into the horizontal oven 325 through opening, or entrance port 309 in the front or entrance end 326

to then emerge as a hot cellular product from the outlet opening or port 360 of the oven. 235 outgoing 327.

The hopper 310 receives a premixed raw or billet charge formed from a mixture of clay, water and carbonaceous material as described above.

The hopper 410 has identical end walls 411, side walls 413, rollers 413, 413a, 413b, 419, curved plate 417, sliding plate 417a and heating device 428 for delivering a compressed, horizontal band 420 of raw clay charge, identical to and above the band 320.

The strip 320 is then fed to a coating zone where glaze or an overcoat (11 engobe") for glaze is sprayed onto the upper side of the strip 320 by means of a nozzle device 329 with a horizontal collection container 329a carrying a number of separate, downwardly directed nozzles 329b. During the outgoing belt 320 is another nozzle device 329c group of nozzles 329d carried by a transverse collection container 329e. The nozzles 329d deliver a separating or release agent to the bottom and perhaps the sides of the belt 320. The release agent is preferably a slurry formed from raw, very hot refractory clay and water and sufficient fluid to allow it to flow through the nozzles 329d.

The nozzle devices 429 and 429c are similar to the nozzle devices 329, 329c. arranged for band 420.

From there, the power-driven rollers 318 and 418 feed the bands' 329, 420 through ports 309, 409 into the furnace 325. Horizontal power-driven or drive rollers 335 receive the band 320 and horizontal power-driven rollers 435 receive the band 420. The upper circumferences of the rollers 335 and 435 form parallel horizontal conveyors which feed the belts 320 and 420 at a uniform speed through the furnace 325, the rollers 335, 435 being driven as shown in fig. 11 and 12.

According to the present embodiment, the furnace 325 is equipped with a number of horizontally arranged muffle plates 330a, 330b, 330c, 330d which divide the furnace 325 over its entire length into a number of alternately separated combustion chambers and ventilation chambers, the combustion chambers forming the longitudinal chambers 347a, 347b and 347c . The upper chamber 347a is thus above the top band 420, the middle chamber 347b is between the upper rollers 435 and lower rollers 335, and the lower chamber 347c is below the rollers 335. The purpose of the combustion chambers 347a, 347b and 347c is to separate the bands 320 and 420 from the combustion gases so that the bands will be in a reducing or neutral atmosphere, at least during the time when the band's temperature is above approx. 800°F.

The muffle plates 330a and 330b thus form between them an upper tubular muffle chamber 431 and the plates 330c and 330d the lower muffle chamber 331 in which the rollers 435 and 335 and the belts 420 and 320 are located. Guiding or muffle plates 330a and 330c are slightly inclined so that. the latter part of the chambers 331, 431 gradually expands towards the outlet ports 360 and 460 and corresponding parts of the chambers 347a and 347b gradually taper towards the end 327.

The muffle plates 330a, 330b, 330c, 330d are preferably formed from plates of fused silica which will allow temperatures in the furnace 325 of up to approx. 2700°F. For the production of such muffle plates, the silica charge for furnace 525 should be provided with a silica or sand glaze along the upper side and then, after firing, the glaze thus formed should be sawed off from the foamed remaining product. A sequence of fused silica plates arranged across side edge to side edge in the furnace will form each of the muffle plates 330a, 330b, 330c, 330d. When mounted, these plates should initially be heated to approx. 2300°F. At this temperature, the plates will gradually devitrify to form cristobalite crystals that have less tendency to subsidence at higher temperatures. Then they can higher temperatures, up to approx. 2700°F is used.

The rollers 335 and 435 project through the side walls 344 of the oven 325, their end portions being supported by wheels or rollers 370a, 370b, 370c and driven by belts 372-as described above for the previous embodiment.

Staggered fuel nozzles 340a, which are arranged in approximately the last half, direct an ignited air and gas mixture across the upper chamber 347a to heat it, while likewise staggered nozzles 340b and 340c do the same for the middle or intermediate ones respectively chambers 347b and 347c. Air lines 300 supply air through branch lines 301 to the nozzles 340a, 340b, 340c, while gas or oil lines 302 and branch lines 303 deliver fuel to these.

At the exit end of the furnace 325, there is arranged an exhaust or exhaust gas device which is identical to the exhaust gas device in fig. 1. It includes a motor 52 which via a belt 53 drives a fan 41 to draw the products of combustion from the outlet end of the chambers 347a, 347b, 347c, through ports 348a, 348b, 348c and manifolds 349, and exiting the same through chimney 354.

As shown in Figure 13c, the ribbons:.• 320a and 420a, after being swollen or cellulated, are fed under the glaze applicators 363 and 463 and thence to annealing furnace or deep furnace 380 which has successive chambers equipped with air systems 419a, 419b, 419c,

419d which dovetail oven is identical to the dovetail oven 80.

It thus appears that the combustion gases which are formed in the rear part of the oven's interior by burning fuel with the aid of the nozzles 340a, 340b, 340c are fed forward towards the front of the oven 325 and flow out of the oven as the charges are moved in counter-current to the exhaust gases. The incoming charge bands 320 and 420 are thus gradually dried, then preheated, then fused and cellulated as they are moved through the oven.

In the fourth embodiment shown in fig. 18a and 18b, a rectangular furnace 525 which has parallel, side-by-side, free-running rollers 535, and drive rollers 536. The rollers 535 receive, from an inclined plane or platform 510, a charge 520 which is advanced in a tray or pan 521. This pan 521 is bumped, by means of a reciprocating hydraulic cylinder 522, through the entrance opening 509 in the front wall 526, into the furnace's 525 combustion chamber. 531. The pan 521 is supported on the furnace roller bed formed by horizontal running rollers 521, and is moved on these by being pushed by means of successive similar pans 521, with their chargers 520, as such pans are successively fed by the cylinder 522 into the furnace 525.

The furnace 525 is heated by means of burners (not shown) as in the previous embodiment and the combustion products are led out by means of a fan 551 through a chimney 554, as they are sucked through outlet ports 548. The pan 521 thus finally reaches the line rollers 536 at the outlet end of the furnace 525 as at impact emits the pan through the temporarily open outlet port or opening 560 (aligned with open 509) when the vertically sliding door 561 of the furnace 5.25 is raised by means of a cylinder 562 to the position shown in broken lines in Fig. 18B.

A motor (not shown) drives, via a unidirectional operation, all the rollers 536, so that a certain resistance to feed along the rollers 536 occurs. This exerts a back pressure which keeps the juxtaposed, successively arranged pans 521 on the rollers 535 and 536 in contact with each other.

A rotatable pin or switch arm 563 which is connected to switch 564 as shown in fig. 18b acts as an electrical control device both for the motor (not shown) for the rollers 536 and the cylinder 562, so that the door 561 is opened when the pin 563 is moved towards the door 560 by means of the porous charge 520a, and the rollers 536 are then influenced so that a tray 521 is carried out from the oven 525. Then the door 561 is closed and a new cycle can begin.

Fuel nozzle (not shown) similar to nozzles 40 and 340a, 340b, 340c heater, furnace 525.

Either trays or pans, such as pan 620 in fig. 19, can be used as the pans such as pan 520 or the pans such as trays or pans 720 shown in fig. 20, 21 and 22 can be used as the successive pans such as pan 520. Pans 620 and 720 can actually be used interchangeably.

As particular reference is made to fig. 19, the sectional trays or pans 620 include a pair of opposing end segments 521 and a number of intermediate segments 622. Each of the segments 622 are channel members with flat, rectangular bottom plates 62 3 and upwardly facing, spaced, parallel, rectangular side plates 624 projecting from opposite edges of the bottom plate 623 .

The end sections are also channel elements with rectangular bottom plate 625 and side plates 626. One end is closed by means of a rectangular end plate 627.

In use, sections 624 and 625 are assembled simply by placing edge to edge on platform 510 to form pan 620 closed on its sides and bottom. The silica charge of raw sand, water and carbonaceous material is hand packed or rammed into the pan 620 and the cylinder 522 is used to push each pan 620 successively into the furnace.

The plates 623, 624, 625, 626 and 627 are formed from plates of refractory material, i.e. pressed carbon, such as coke powder or charcoal granules. Pitch or tar can be used as a binder for the coke or charcoal and as an adhesive for joining the edges to be joined.

When the sand melts in the furnace 525, the charge holds the segments or sections 622, 623 together until the charge has cooled after it has melted and formed cells. The fused silica can be cooled quite quickly and does not need annealing. There is thus no need for a swallow furnace. External rollers 566 in front of rollers 536 deliver silica to an area where it is cooled and sections 621 and 622 are removed for reuse.

Referring to fig. 20, 21 and 22, another form of split pan 720 includes a number of mutually opposed flat rectangular intermediate bottom plates 723 and end plates 723a each provided with a pressed or compressed straight prism or rectangular block 724 of silica charge. A conventional press (not shown) may be used to compress each block 724 onto its associated bottom plate 723 or 723a, or the blocks may be pressed separately and then placed on the bottom. The outer or side ends 725 of the block 724 should end within the end edges 726 of the bottom plate 723. The sides 727 of each block 723 should end flush with the side edges 729. The outer edges 729a of the end blocks 724a should end within the outer edges 729a or the end plates 726a.

The plates 723, 723a thus, in the assembled state, have circumferential portions which receive longitudinal, mutually separated, parallel side rods 730 and mutually separated, parallel, transversely running end rods 731 which form elements of a removable edge, which rests on but is not attached to the plates 723, 723a as shown in fig. 21. The rods 730 extend the entire length of the juxtaposed plates 723 and 723a, while the rods 731 lie within the ends of the rods 730.

In the assembled state, the pan 720 has the individual blocks 723 and 723a in contact with each other. These blocks 723 and 723a fuse together as the silica charge formed by the blocks 723, 723a melts and forms cells while passing through the furnace 525.

As shown in fig. 22, vertical running rollers 580 which are arranged at a distance from each other in the oven 525 guide the pans, such as pan 720 through the oven 525, the rollers 580 preventing significant outward movement of side rods 730 and the rods 731 preventing significant inward movement.

The elements, namely 723, 723a and rods 730, 731 are fairly easily pulled from the monomitic rectangular product after it has formed cells, fused and cooled.

Thus, a small press (not shown) can be used to produce a very long porous fused silica product.

The boards. 620 and 720 are cheap and not intended for many times of use. It is therefore assumed that one, two or three uses are all they can withstand. As they are made of carbonaceous material or carbon, they can be consumed by oxygen and water vapour. They thus act to form a reducing state around the charge and when the hot plate and charge are carried out into the atmosphere they can be consumed by

the ambient air.

The fact that the trays are not permanent allows the use of fuel such as gas, oil or solid fuels, i.e. wood or coal in the oven to form combustion products such as steam. These combustion products are consumed by reacting with the carbon in the trays.

In any of the designs where either a clay charge or a silica charge is used and if the furnace 25, 225, 325 or 525 is approx. 40 feet long, the feed speed through the furnace should be such that the charge is kept in the furnace for approx. 10 to approx. 60 minutes, depending on the thickness of the charge. Thus, a 3/8 inch thick charge should be moved by approx. 2 feet per minute to keep it in the furnace for 20 minutes while a charge five inches thick should be moved at one foot per minute.

The distance between the rollers in the furnace should be such that significant shrinkage is avoided, especially after the charge has fused and is in a relatively viscous state. In the last part of the oven, it should therefore be ensured that the rollers are arranged with a mutual distance of less than approx. five inches between centers. This will also vary with the thickness of the charge. If the charge is thin, i.e. approx. 3/8 inch, the rollers should be arranged with approx. lh inch distance between the centres, and if the charge is thick, e.g. five inches thick, the rollers should be arranged with the centers about four inches apart.

In the furnace in front of the point or zone where melting takes place, the bands are sufficiently self-supporting that the rolls may be between six inches and twenty-four inches apart, center to center.

The charges, which are stored on plates or in trays, have no such sagging problems, as the carbon plates are sufficiently rigid to form a support. The rollers should, however, be in sufficient number for two or more rollers to support a section of a pan at any time.

More densely arranged rollers interrupt the continuity of the vertical wall, completely, or leave very thin columns of refractory wall and/or lining between the rollers with little clearance around the rollers.

With conventional refractories, it is difficult to maintain wall support above the rolls, due to movement and shear forces due to thermal expansion, particularly in multi-deck and muffle furnaces. For this reason, the furnace is usually built from fused silica, in all parts that are exposed to no more than approx. 2700°F, and bearing wall sections on the cold sides. Solid or cemented layers do not peel off as a result of differential expansion.

It should be noted that at the usual working temperatures

in the heat zone, the molten silica will tend to devitrify over time, so that it is converted into cristobalite, which has a discontinuous thermal expansion below approx. 600°F. The furnaces are usually in operation for months at full temperature, and it is easy in this case and in many other operations to

hold the devitrified parts above 600°F using a small holding fire.

METHODS OF PROCESSING

Based on the above description, the operation or procedure when using the device will be clear. A charge that can be satisfactorily processed into a foamed or swollen clay product consists of 100 parts by weight of clay, from approx. 6 parts for approx. 15 parts water, and from approx. 1/20 part to approx. 2 parts available carbon in carbonaceous material. I call this a moist clay charge or mixture.

The clays that I have found useful as raw materials include surface clays, ball clays, kaolin, shale and bentonite. Other clay-like materials can be used for my method, the essential property being the material's small, finite particle size and the ability to sinter into an impermeable mass. Thus, clay and clay-like materials having an average particle size of -less than 2 µm are particularly suitable in my method. Such clay is found in nature in the form of stone. It should be crushed into granular form, so that it can typically pass through a 6 mesh sieve.

There are countless organic or carbonaceous substances that can be used as the carbonaceous material in my process. However, they must be soluble in water and must be charred by heating. Thus, sugar or sodium lignite (Orzan A) are very useful as the carbonaceous material.

It should be remembered that if organic materials are present in the clay itself, soluble carbonaceous material is used in smaller quantities so that the sum of the naturally occurring carbonaceous material and added available carbon is up to approx. 2 parts per 100 parts clay.

Another charge that can be processed into a foamy, molten mineral consists of silica, carbonaceous material and water.

A useful silica raw material is a sedimentary quartzite that naturally occurs in massive form with an average crystallite diameter of approx. 10 2 um and less, preferably between 5 and 10 2 um, and which contain insignificant amounts of intercrystalline material. A preferred useful silicate raw material contains at least 99% SiO 2 , on an oxide basis. Such a silica raw material can be found, e.g. in Arkansas, Illinois and California and has the following typical chemical composition:

In practice, the quartzite material is crushed after it has been removed from the mine, so that it typically passes through an approx. 6 mesh sieve. If a purer form of silica is desired, a silica flour obtained by finely grinding quartzite sand or gravel should be used. Addition of colloidal silica improves the surface area of the quartzite as will be explained below.

The charge is formed by mixing 1000 parts of silica and from approx.

k part to 4 parts available carbon in soluble carbonaceous material and sufficient water for thorough distribution of the soluble carbonaceous material and the colloidal silica if this occurs. It is therefore recommended from approx. 50 to approx. 100 parts water. The silica charge must be placed on plates which are fed end to end through the furnace 25 instead of belts 20, 120.

Another form of silica raw material is diatomaceous earth, which is a very porous form of silica and which foams rather easily. However, it is not a pure form of silica and its lack of resistance to acids reduces its applicability.

In processing either the clay charge or the silica charge, the charge is compressed using either a low-pressure press or rollers, such as rollers 13 and 19. The clay charge is extruded into belts 20, 120. The silica charge may, however, require carrier plates or carrier nets 200 along its underside.

The carrier plate 200 is extendable and if a carrier plate is used, it is produced in the same press where the charge is compressed. The plate 200 is formed from a binder and carbon material. It preferably consists of a binder and carbonaceous material such as pitch and fine-grained coke or pitch and coal dust, according to common practice when forming carbon. The plate 200 is produced on a sheet of aluminum foil or other release or separating agent 201 in the press 202 so that it does not stick to the heated plate 203. The aluminum will melt in the furnace 25 and burn up.

If desired, silica sand of a purity equivalent to the silica placed in the interior space can be placed on the upper surface of the silica charge (without a blowing agent) to form a glaze during firing.

When the fused, vitreous, cellular silica is melted and as the successive silica charges in the chamber 32 bump against each other as they are advanced through the chamber 32, the silica mass in one plate 200 fuses with the silica mass on the next so that the band formed by the silica mass. in the oven 25 gradually becomes uniform.

It should also be noted that the plates 200 should be removed from the band of fused silica as soon as the cellular fused silica has cooled.

When the charge enters the oven 25, it is exposed to a temperature of approx. 600°F regardless of whether it is a silica charge or a clay charge, and it is gradually exposed to increasing temperature so that when it reaches the end of its travel in the chamber 31, the charge is exposed to ambient temperatures of from approx. 50°F to approx. 200°F lower than the temperature of the gases in the combustion zone or chamber 32. The charge then enters the combustion chamber 32 where the temperature must be maintained e.g. as follows: For surface clay chargers and bentonite chargers 2000°F to 2300°F. For other clay chargers 2100°F to 3100°F. For silica chargers 3000°F to 3300°F.

In any case, the temperature and turbulence, which determine the heat transfer characteristics, should be such that there is no more than approx.' 150°F temperature difference between the surface temperature of the charge and the lowest temperature in the interior of the charge.

Although the firing times and temperatures vary with each raw material and the thickness of the final product, I have found, using California clay mined near Corona, that tile 1" to IV thick and weighing about 5 pounds per square foot can be made by preheating the charge for about 30 minutes and then firing for about 30 minutes at a temperature in the combustion zone or chamber 32 of about 2140°F.

Sintering of the charge usually takes place when the charge is approx. 100°F to approx. '500°F below the melting point of the clay or silica mass in the charge. Sintering can thus largely take place in the preheating chamber 31.

In the chamber or combustion zone 32 the charge will gradually swell or expand as cell formation takes place and at the outlet from the chamber 32 the foamed or cellular raw material has a density of 8 pounds per cubic feet to approx. 100 pounds per cubic foot and has a vitreous, vitreous, cellular structure of mostly non-interconnected cells.

When good results are obtained, 98% of the cells have a diameter of less than 2 mm and in many cases less than 1 mm. This fine cell structure gives uniform thin cell walls which simplify production.

If the raw material is silica so that a foamed fused silica product is produced, it is not necessary to feed the product to the annealing-swivel furnace 80. Instead, it must be rapidly cooled to approx. 2000°F.and then as quickly as one sees fit.

With all "other materials, the product must be fed to the annealing swallow furnace 80 and there gradually cooled. For best results, the annealing curve" for each product should be determined experimentally.

When making roof tiles from Corona clay as described above, a curve similar to that for 1/4" thick plate glass gives good results.

As stated above, when the foamed or cellular clay strips 20a, 120a which are now fused or glassy enter the deep-flow oven 80, they are initially cooled rather quickly in the oven 81 by introducing ambient air by air circulation towards the strip surfaces. This reduces the temperature

in bands 20a, 120a to close to the annealing temperature. The product is then passed through the annealing chambers 82a, 82b, 82c, 82d where the strips are gradually cooled and then fed out to the rollers 93, 193, and exits at a permissible temperature for completion of cooling on the rollers 93, 193.

The speed of the belts or plates through the furnace 25 and the flue furnace 80 is from approx. 3" per minute to about 72" per minute and the distance between the rollers 36, 136 towards the outlet end of the chamber 32 is from approx. 1" to about 6" between centers.

The viscosity of the material during cell formation is from approx. 4.8 x IO<6>poise to 5.2 x IO<6>poise, and the material does not sag between the rollers.

From a theoretical point of view it is known (Norton's text "Refractories") that ferruginous clay melts at temperatures as much as 200°F lower under reducing conditions than under oxidizing conditions. When producing the clay charge that makes up bands 20 and 120, I therefore incorporate soluble carbonaceous material and water in the clay in such proportions that the solution of carbonaceous material covers all the particles in the clay. Thus, a strip of moist clay is produced by compaction under low pressures from 50 psi to 1000 psi, the clay being sufficiently loose that the moisture during the initial heating is driven out of the mixture, leaving the carbonaceous mixture as a very thin coating on all the base particles in the camp. The carbonaceous mixture, such as sugar, is uniformly distributed throughout the mass and is thoroughly added to each particle as a coating thereon. Further heating of the clay charge causes it to sinter, during which cracks may appear in the surface.

In the chamber 31, however, the atmosphere has an excess of air or oxygen and is therefore an oxidizing atmosphere. One or more surfaces of the bands 20 and 120 are kept in this oxidizing state from just before fusion of the band or plate until it is released to the colder temperatures. The temperature immediately before sintering and during firing is sufficiently high that the carbon in the surface area of the charge is burned out to a limited depth from the surface of the clay. A shell of material with a high melting point is thus formed partially or completely around the band 20 or 120 or the plate.

In the interior of the charge, however, there are reducing conditions as a result of the presence of the organic or carbonaceous material. Thus, under carefully controlled temperature conditions in the combustion chamber 32, the bands 20 and 120 will be held so that the shell does not melt or become too sticky to be able to run over the rollers, while the main part of this, charge melts. As the clay melts, the iron oxide in the clay and the carbon on each particle surface can diffuse so that they react with each other to release carbon monoxide and carbon dioxide into the molten viscous clay, causing the clay to swell by forming a series of closed bubbles.

If a release or separating agent is used for the bottom surface of the belt 20 or 120, or its bottom and side surfaces, this release or separating agent is more inert when heated in the oven than the clay itself and thus does not stick to the surfaces of the rollers. Furthermore, this release or separating agent, if applied to three sides, will form a cradle under and on the sides of the belts 20 and 120, which encloses the charge during the period when it is foaming or forming cells.

I have also found that when cell formation occurs in the combustion chamber and the temperature is maintained so that the viscosity of the clay remains at approx. 5 x 10 poise, the clay is sufficiently sticky to stick to the rollers that carry it, if the oxidizing or other release agent is not present, and is nevertheless sufficiently viscous that the gas produced by reaction between the carbonaceous or organic material and the iron oxide or the like oxides in the clay create small bubbles that do not burst, but expand the clay and form closed cells of largely uniform consistency.

By adjusting the clay's carbon content, the right amount of gas is formed to give the desired density. Regulating the humidity and the degree of pressing produces a clay strip that is sufficiently strong to be able to run over the rollers, but not so dense that it requires a long drying time at a low temperature.

The carbon reduction of the iron oxides and other oxygen-rich mixtures in the clay is possible at lower temperatures. However, a significant part of the reaction is delayed until the charge melts. It is an essential feature of my method that the carbon coating is deposited on each small basic particle in the interior of the large agglomerated particles of the clay as it is mined or crushed. Thus, when the clay melts and molecular diffusion accelerates, the physical meeting between the iron oxide and the carbon takes place over a very short distance and the reaction takes place quickly. This phenomenon acts as a built-in control for the production of gas after sintering but quickly during melting.

Some porous rocks of compressed quartz crystallites are formed with crystallites or particles almost as small as the basic particles in clay lumps. Diatomaceous earth is also silica with a small basic particle size, but less pure than the purer sand. These silicas, such as quartz crystallites or diatomaceous earth (kieselguhr), have a larger specific surface area than powdered sand, and therefore larger interfaces. In other words, a thinner layer of carbon covers a smaller depth of silica and the molecular diffusion is thus faster as a result of a shorter path. In some cases, the carbon reacts with the silica material to form silicon carbide which then on further heating reacts with further silica to form silicon monoxide and carbon monoxide which are the gases in a silica body or in a high temperature aluminum silicate such as ball clay.

In my preferred method of making the foamed fused silica of a purer composition, I add sugar and water to a small amount of off-the-shelf colloidal silica solution which is then thoroughly mixed with off-the-shelf silica flour. This gives a dispersion of carbon over a much larger surface area than would otherwise be achieved even by grinding the silica material down to a minimal size.

The silica flour has a particle size of approx. 15 µm equivalent diameter, while colloidal silica is approximately 1000 times smaller. This means that the surface area of a given mass of colloidal silica has 1000 times the surface area of the same mass of silica flour. I thus use approximately 2 parts by weight of colloidal silica to 100 parts by weight of silica flour and thereby increase the effective surface area of the silica flour by approx. 20 times. This proportionally increases the area of the interface for reaction between the carbon and the silica material. Thus, when the silica charge, colloidal silica and carbon are heated in the furnace 25, the carbon is fairly evenly distributed in the silica material, and on heating the moisture is driven away and the carbon finally reacts with the silicon to form silicon carbide and then the silicon carbide reacts with the silica to form silicon monoxide and carbon monoxide .

Cellular, vitreous, fused silica product can

also made from the crushed silica, such as quartzite or diatomaceous earth, to form agglomerates with a diameter of less than one h". These crushed stones are mixed with colloidal silica sol and a soluble carbon substance, which is charred by heating, dissolved in water. The solution will need through the agglomerates and cover the small particles in them. The subsequent heating will • drive away the moisture, leaving the colloidal silica and carbon evenly distributed on the particles. Continued heating will cause a reaction between the carbon and the available silica and between the carbon and available oxygen to causing cell formation as the silica material melts.

According to my invention, suitable foamed materials can be made from surface clay, shale clay, bentonite, diatomaceous earth and silica. Surface clays and shale clays mined from brick, tile and potting plants in California, Georgia and

Germany has been found suitable for my methods. Such clay

and shale clay can be crushed so that it typically passes through a 6th mesh per empty sight.

Swelling bentonite from Wyoming and. South Dakota and non-swelling bentonite from Mississippi and California are also useful for making foamed material according to the present invention. All these clays (shale clay and bentonite are referred to as a clay) have been successfully treated in the following way: In successive batches, sugar and sodium lignite (ORZAN A) were dissolved in water and then the water was mixed with the clay so that it assumed a wet press consistency. In some cases where the clay had a high moisture content, the clay was mixed with drier clay to form a final moisture content of 6 to 15 percent by weight. Also when only 3% or 4% of the total water was added to the clay the sugar or sodium lignite was added

this water before it was mixed with the clay.

The various samples of the resulting mixtures were each pressed into cakes in flat forms or they were hand-packed onto carrier plates. The pressed cakes were dried before firing. Cakes or loose packages on carrier plates were individually pushed into a laboratory oven at approximate temperatures determined by observation of the state of swelling. The temperatures used were from 2050°F to 2250°F. All clays showed cell formation.

I have found that in some types of clay there are natural deposits of organic material containing carbon. These organic materials are evenly distributed in the clay and pose no problem except that they must be taken into account. It is thus in some cases not necessary to add carbonaceous material to the clay. In some cases, where extremely high organic matter content occurs in the clays, they should be mixed with other clays so that the resulting charge has approx. 2% by weight of organic material in the mixture. If more than approx. 2% organic material present in the mixture results in strong swelling and irregularities in the cell structure. When less swelling or foaming is desired, the organic material in the charge is reduced accordingly. This can be done by mixing with other clays with a lower organic content. The resulting foamed or cellular clay will be more uniform with less dense cell formation. In the production of fillers with all the above-mentioned clays, shale clays, bentonites, impermeable surfaces were obtained in all cases

cellular pieces of great uniformity, except where an excess of organic matter occurred.in the charges.

My invention will be better, understood on the basis of the following particular examples.

EXAMPLE I

A clay from Fremont, California (Interlocking Tile Co.) passed through a 6 mesh sieve was mixed as follows:

1000 parts clay

10 parts sucrose

110 parts tap water

A 12" square brick or tile was formed by press-

sing at 100 psi to approx. 1" thickness.

The chip was placed in a 700°F atmosphere for 15 minutes, then in a controlled atmosphere whereby the chip was substantially sintered without burning off the carbon developed from the sugar, when the temperature was raised to about 2000°F in a reducing atmosphere.

The tile was passed over rollers with approx. 12" per minute for 20 minutes in a furnace at approximately 2100°F in an oxidizing atmosphere. The rolls were clean and new prior to this test and the chip passed over without stopping due to sticking to the rolls. There was no sign of sagging between rollers. The tile had expanded to about 16" x 16" and had a reddish-brown skin due to the skin oxidation. The interior was dark gray-green with cell formation to about 30 pounds per cubic foot.

Repeated attempts were made and some sticky spots, of molten clay or glaze from various attempts had settled on the rollers and began to pull off pieces of oxidized skin as the adjacent inner material softened and formed cells.

EXAMPLE II

Tile blanks from Example I were painted on the bottom and sides with an engobe of raw and calcined, high-temperature refractory clay after initial drying.

These tiles were fired as in Example I and showed less tendency to cause sticky spots on the rollers, but where a sticky spot did occur there was still a tendency to tear off the coated and oxidized skin, which could build up until the conveyor was deployed. of operation. The tile expanded laterally to approx. 16" x 16".

EXAMPLE III

A mixture of 60 parts calcined fireclay to 40 parts raw fireclay and 10 parts water was spread over the bottom of a mold and brushed up the sides. The mold was then filled with the clay charge from example I and the tiles, otherwise pressed as in example I.

These tiles were fired as in example I and expanded during cell formation to approximately the same density. It was noted that while the tile had expanded laterally to approx. 16" x 16" in examples I and II, the tile according to this example had expanded

in thickness instead of laterally.

EXAMPLE IV

A release agent was prepared by mixing 12 parts raw refractory clay and 88 parts silica sand and 10 parts water. This mixture was used to make the bottom coating of the tile according to Example I and treated as in Example II. When the tile with this bottom coating was passed over the rollers during firing, the sand, which was exposed to a sticky spot, was torn off only when in contact with the spot, until the sticky spots on the rollers were completely covered. In subsequent trials, these rollers were again able to receive the clay charge without the charge sticking.

EXAMPLE V

Chips similar to the chip in example I were made from Wyoming bentonite instead of clay and the sugar addition was reduced to approx. 2 parts per 1000 parts bentonite. At a burning temperature of approx. 2300°F similar results were obtained as under Examples I, II and III.

EXAMPLE VI

In the bottom of the mold I spread out a sheet of aluminum foil and spread out a dry mixture of 2 parts powdered petroleum coke and 1 part powdered pitch from the supply house of a foundry. The mold was then heated using a gas flame to melt the pitch, then it was pressed to produce a carbon plate. This process was repeated to produce additional carbon sheets from less than 1/16" thick to more than 1/8" thick.

The carbon plates were then cooled and loaded with a charge approx.

8" x 8" x 1" by placing a mold on the plate and filling the mold and tamping by hand.

For this example VI, the charge was Mississippi M&D ball clay mixed with sucrose and water as in example I. The sample was fired on one of the carbon plates, being brought directly from room temperature into the furnace at approx. 2800°F, where it was fired for approx. 20 minutes. The temperature was regulated by trial and error to achieve good cell formation.

In all of the above examples, they fragmented cellular samples that were brought into cold air from the oven. At the end of a test, individual specimens were placed in an annealing box and the cooling rate adjusted to yield unbroken specimens.

EXAMPLE VII

This was a repetition of Example VI, except that crushed diatomaceous earth was used instead of the clay. The temperature was regulated by observing the melting and cell formation, and was assessed to be approx. 3100°F. The sucrose addition was approx. 2 parts per 1000. Good cell formation was achieved at approx. 20 pounds per cubic feet, and the product did not burst when brought from the furnace temperature into cold air.

EXAMPLE VIII

The procedure according to Example VII was repeated except that porous quartzite stone (see Table I) was crushed and used instead of the diatomaceous earth. The burning temperature was approx. 3200°F; Rapid cooling was beneficial and cell formation was good after approx.

30 minute burn.

EXAMPLE IX■

The procedure of Examples VII and VIII was followed except that the charge was a purer quartzite silica, essentially a purchased 325 mesh silica flour, 99.8% pure silica.

For this charge per 1000 parts were added to 4 parts sucrose in 49 parts water and 80 parts silica sol containing 30% of the silica sol as colloidal silica with a diameter of 15 mm.

Burning took place on the carbon plate at approx. 3200°F for approx. 30 minutes. The sample was quickly cooled after it had been taken out of the oven and the carbon scraped from the plate. Cell formation was good at a density of 18 to 24 pounds per square meter. cubic feet.

EXAMPLE X

Samples of approx. 20 surface clays were collected from California, Georgia and Germany. All of these were tested according to Example I, with the addition of more or less and no sugar. All the samples showed favorable cell formation.

Six commercial ball clays and one Georgia kaolin were also formed on carbon sheets and expanded during cell formation by

using the above procedure.

It will be clear within professional circles that many variations can be carried out in the embodiments that are here chosen for the purpose of illustrating the present invention, and that the doctrine of equivalents applies in full without deviating from the scope of this invention as defined in the appended claim.

Claims (55)

1. Device for burning refractory raw material, characterized in that it includes: (a) a longitudinally arranged furnace having an inlet end and an outlet end and having openings defining a front inlet port and a rear outlet port for raw material conveyed through the inner space of the furnace; (b) conveyor means in the furnace room for supporting and advancing the raw material from the entrance port along a prescribed, generally linear path in the furnace room and out through the exit port; (c) fuel-burning means in the rear part of the furnace chamber for burning the raw material as it is advanced through the furnace chamber; (d) guide plates arranged generally horizontally in the furnace space for dividing the furnace space into combustion chambers and an intermediate muffle chamber, the transport means being arranged in the muffle chamber; (e) outflow means near the entrance end of the furnace for discharging the combustion gases from the combustion chambers, whereby the hot gases which by means of the fuel-burner means flow into the front part of the combustion chambers move backwards over and under the raw material in a counter-flow relationship; (f) delivery means for delivery of the raw material into the entrance. 2. Device according to claim 1, characterized in that the muffle plates are formed from juxtaposed plates of fused silica. 3. Device according to claim 1, characterized in that the delivery means include a hopper for the raw material, which hopper has an opening in its bottom part, a pair of opposing pressure rollers arranged on opposite sides of the opening for conveying the raw material as a downward stream, a third pressure roller under a of said opposing pressure rollers, and guide means for guiding a surface of the flow from the second of said opposing pressure rollers to the third pressure roller, the opposing pressure rollers compressing and advancing the raw material from the hopper in a stream which is advanced in a downward direction and while it third roller and one of the opposing pressure rollers cooperate to advance the flow as a band of indefinite length in a horizontal direction into the entrance port. 4. Device according to claim 3, characterized in that the guide means include a curved plate which is concentric with said one of the opposing pressure rollers. 5. Device according to claim 1, characterized in that it includes. a number of nozzles arranged between the delivery means and the furnace for spraying material onto the surface of said raw material. 6. Device according to claim 1, characterized in that the fuel-burner means include a number of gas or oil burners arranged in a mutually offset relationship in opposite walls of the oven... 7. Device for advancing raw material as a band in a horizontal direction, characterized in that it understands: (a) a hopper for the raw material, which hopper has an opening in its bottom portion, a pair of mutually spaced, transversely opposed pressure rollers, the inner circumferences of which are arranged on opposite sides of the opening for opposing sides and compression and gradual advance of the raw material as a downward stream; (b) a third pressure roller below said one of said opposed pressure rollers, and guide means for guiding a surface of the flow from the second of the opposed pressure rollers to the upper circumference of the third pressure roller; (c) as said opposing pressure rollers are compressed and advance the raw material from the hopper in a stream which is advanced in a downward direction; and (d) -wherein the third pressure roller and said one of the opposing pressure rollers cooperate to compress and advance the flow as a band of indefinite length in a horizontal direction. 8. Device according to claim 7, characterized in that the guide means include a curved plate concentric with said one of said opposing pressure rollers. 9. Device according to claim 8, characterized in that it includes end rollers at the ends of the opposite pressure rollers. 10. Furnace for burning refractory raw material, characterized in that it includes: (a) a longitudinally arranged furnace having an interior space and an aligned inlet opening and an exit opening for the furnace; (b) a roller bed in the furnace chamber; (c) an impact device near the entrance opening for thrusting successive charge pans into said pan such that one pan forces the next along the roll bed towards the exit opening; (d) powered discharge rollers in one end portion of the furnace for discharging the outermost pan from the furnace through the exit opening; and (e) means for detecting when the outermost pan is on the discharge rollers and for then activating the rollers. 11. Device according to claim 10, characterized in that the driven rollers can rotate freely when they are not driven. 12. Tray for receiving a charge, characterized in that it comprises a number of sections including flat bottom plates made of a refractory material and arranged end to end, an edge for the flat plate, which edge includes edge elements that are made of refractory material and can are removed from each other to allow the plates to be disassembled from each other. 13. Fold according to claim 12, characterized in that the elements are longitudinal side bars that extend over all the edge parts of the plates and end rods over the edges of the end plates. 14. Fold according to claim 12, characterized in that the elements are pairs of upright opposite plates which, together with the bottom plates, form juxtaposed removable channel elements and end plates which close the ends of the outermost channel elements. 15. Board according to claim 12, characterized in that the refractory material includes carbonaceous material selected from the group consisting of fine-grained coke and coal granules. 16. Board according to claim 15, characterized in that a binder selected from the group consisting of pitch and tar is mixed with the carbonaceous material. 17. Board according to claim 12, characterized in that it includes a charge of silica in the board. 18. Fold according to claim 12, characterized in that each bottom plate carries compressed individual blocks of the charge, which block is juxtaposed above the plates. 19. Process for the production of a cellular, glassy, fused silica product, characterized in that it comprises crushing the silica cast selected from the group consisting of quartzite stone, and diatomaceous earth to produce agglomerates smaller than V' in diameter, mixing the the crushed silica cast with colloidal silica and a solution in which a carbon mixture, which will char on heating, is dissolved in water, whereby the solution will penetrate the agglomerates and cover the particles of which the agglomerates are composed, draining the water from the agglomerates and charring to leave the carbon mixture as a coating on the particles, then melting the agglomerates at a temperature which will cause the carbon deposited on the particles to react with gel silicon and oxygen to effect cell formation in the fused silica, and then cooling of the celled silica. 20. Device according to claim 19, characterized in that the press means include a press with a heated press plate. 21. Device for burning mineral mixtures of the kind that has a furnace body with opposite side walls, a top that extends between the side walls and a bottom and where a support device carries the charge at a prescribed height in the furnace body between the side walls, characterized in that it comprises : (a) a number of longitudinally spaced individually controllable fuel burners supported by both side walls and arranged above and below the height of the charge, which fuel burners direct flames in the t<y> direction of the furnace body; and (b) which side walls are each provided with exhaust ports transversely opposite the fuel burners for the discharge of the gases created by the burners. 22. Device according to claim 21, characterized in that the fuel burners carried by one of the side walls are offset in relation to the fuel burners carried by the other side wall, and that each of the exhaust ports is arranged between such burners. 23. Method for burning a refractory material, characterized in that it comprises the preparation of a mixture of clay, water and up to 2 parts available carbon of carbonaceous material per 100 parts clay, thoroughly mixing the mixture, gradually pressing the mixture into a strip and gradually advancing the strip along a prescribed path having successive first and second zones, gradually drying and preheating the strip in the first zone and then gradually burning the strip in the second (third) zone to a temperature that exceeds approx. 2000°F so that a swollen band is gradually produced by reaction between the carbonaceous material and oxygen in the clay so that gases are formed which produce a number of closed cells which swell the mixture as it becomes vitreous and then gradually advance the vitreous mixture into a cooling zone which a leash. 24. Method according to claim 23, characterized in that the carbonaceous material is selected from the group consisting of sugar, urea, sodium lignite and other soluble organic mixtures which are charred by heating. 25. Method according to claim 24, characterized in that the water constitutes approx. 6 to 15 parts per 100 parts clay. 26. Method according to claim 25, characterized in that the cellular material is cut into a rectangular shape and that the roof is formed by the rectangular shapes. 27. Refractory product, characterized in that it consists of a band of glassy clay which has a cellular structure and amounts from approx. 8 pounds per cubic feet to approx. 100 pounds per cubic foot, which glassy clay is a band of indefinite length. 28. Refractory product, characterized in that it comprises a vitreous cellular silica block with glaze along one surface. 29. Method for the production of cellular refractory material, characterized in that it includes: (a) preparing a charge formed from a refractory mineral, a blowing agent and water; (b) gradually guiding the charge in a continuous band, guiding the charge gradually as a shaped band in a horizontal path through a preheating zone and then as a shaped band in a horizontal path through a firing zone; (c) heating the strip gradually in the preheating zone to expel water from the charge; (d) heating the refractory and the blowing agent in the shaped band sufficiently while gradually moving the charge as a shaped band through one of the zones so as to sinter the same; (e) continued heating of the strip in the burning zone at such a temperature that the refractory material melts and the blowing agents produce a gas for the cellulation of the refractory material; and (f) then gradually cooling the cellular refractory mineral ribbon as it moves along the prescribed path. (e) continued heating of the strip in the burning zone at such a temperature that the refractory material melts and the blowing agents produce a gas for cell division of the refractory material; and (f) then gradually cooling the cellular refractory mineral ribbon as it moves along the prescribed path. 30. Method according to claim 29, characterized in that the prescribed path is formed by the upper circumferences of a number of spaced apart parallel rollers. 31. Method according to claim 29, characterized in that the solid materials are selected from the group consisting of surface clay, ball clay, bentonite, shale clay, quartzite stone, diatomaceous earth, silica flour. 32. Method according to claim 30, characterized in that the foaming agent is a soluble carbonaceous material which is initially dissolved in water. 33. Method according to claim 32, characterized in that the carbonaceous material is selected from the group consisting of sugar, urea and sodium lignite. 34. Method according to claim 32, characterized in that the refractory material is sintered at a temperature of from 100°F to 500°F below the melting temperatures of the refractory mineral. 35. Method according to claim 34, characterized in that the sintering takes place in a reducing atmosphere. 36. Method for producing a cellular glassy clay product, characterized in that it comprises: (a) preparing a mixture consisting essentially of 100 parts of a clay material and up to two parts of available carbon in a water-soluble carbonaceous material and water; (b) forming the mixture into a prescribed shape using pressure of less than 1000 psi; (c) subjecting the mixture to the prescribed form of heat to expel water from the mixture-, (d) exposing the mixture in the prescribed form sufficient to sinter the material; and (e) then firing the shaped sintered mixture at a temperature sufficiently high to melt the clay material and allow the carbon to react to evolve gas for cell formation in the clay material. 37. Method according to claim 36, characterized in that water constitutes three to eighteen parts. 38. Process method according to claim 37, characterized in that the mixture is formed into a band and is gradually guided along roller conveyors during heating and cell formation. 39. Method according to claim 38, characterized in that the mixture is provided with a release or separating agent on one side. 40. Method for providing a charge for a furnace, characterized in that it comprises a mold space that covers the bottom of the charge with a release agent, applying a mixture of solid carbonaceous aggregate and binder over the release agent, placing a charge of mineral and cell forming agent on the mixture and compression of the same. 41... Process for the production of vitreous, cellular silica, characterized by passing through a furnace containing rollers a charge of silica and a cell-forming agent, which charge is supported on a non-permanent carbon plate that touches the upper circumference of the rollers. 42. Method for producing a cellular, vitreous, refractory material in a furnace having a rectilinear path through the furnace, characterized by forming the refractory material and a blowing agent into a rectilinear band, continuously advancing the rectilinear band along the path through the furnace while maintaining the strip in its rectilinear shape and gradually heating the strip during its rectilinear movement through the furnace whereby parts of the strip are gradually dried, sintered then melted and cellulated. 43. Method according to claim 42, characterized in that the belt includes a number of side-by-side charges of the refractory material and an edging agent arranged on successive plates which move with the belt along the rectilinear path. 44. Method according to claim 42, characterized in that the refractory material is clay and that the blowing agent is a solution of carbon-containing material which dries and chars when heated. 45. Method according to claim 42, characterized in that the refractory material is a silica selected from the group consisting of silica flour, diatomaceous earth and the silica cast. 46. Method for producing a cellular, vitreous . fused silica product, characterized in that it comprises crushing the silica cast selected from the group consisting of quartzite stone and diatomaceous earth to produce agglomerates smaller than V' in diameter, mixing the crushed silica cast with a solution in which a carbon mixture which is charred by heating is dissolved in water, after which the solution will penetrate the agglomerates and coat the particles of which the agglomerates are composed, draining the water from the agglomerates and charring to leave the carbon mixture as a coating on the particles, then melting the agglomerates at a temperature which will cause the carbon deposited on the particles react with available silicon and oxygen to cause cell division of the fused silica, and then cooling of the cellularized silica. 47. Process for the production of a cellular, vitreous, fused silica product, characterized in that it comprises a mixture of silica flour and colloidal silica and a solution containing a carbon mixture which will char when heated dissolved in water whereby the solution coats the particles, in the flour and the colloidal silica , driving off water from the solution and charring to leave a carbon coating each particle and then melting the mixture to cause the carbon to precipitate for cellularization of the fused silica and cooling of the cellular silica. 48. Method according to claim 47, characterized in that the colloidal silica consists of from approx. 3 percent by weight to approx. 25% by weight of the silica flour. 49. Process for the production of a glassy, cellular clay product, characterized by mixing clay containing iron oxide with an aqueous carbonaceous solution to produce a charge, gradually advancing the charge in a rectilinear path over rollers in a furnace, heating the charge in the web to first drain water from the mixture, then gradually sintering the mixture in the web under oxidizing conditions in the furnace so that a skin is gradually produced for the charge which melts at a temperature higher than the melting point of the interior of the charge, gradually heating the sintered charge in the path as it is moved along the rollers to a temperature at which the interior melts and forms cells but the skin does not, whereby the skin along the bottom surface of the charge prevents the molten charge from sticking to the rollers, and then gradual cooling of the charge. 50. A method according to claim 49, characterized in that it includes applying a liquid slurry of raw clay and calcined clay gradually to the lower surface of the charge prior to sintering the charge to produce a release or release agent to assist the skin in preventing the charge from sticking to the rollers. 51. Method according to claim 49, characterized in that it includes pressing a release agent comprising a mixture of silica sand, refractory clay and water, to the bottom surface of the charge before sintering the charge to produce a sacrificial surface which will be released to the rollers where the rollers where the rollers are sticky . 52. A method according to claim 49, characterized in that it includes gradually pressing on the lower surface a mixture of raw clay and calcined clay which is more refractory than the charge to produce a surface to help the skin to prevent sticking of the charge to the rollers and to maintain the charge's expansion in the lateral direction. 53.. Method according to claim 49, characterized in that the clay is in the form of crushed stone which forms agglomerated particles, each of which contains a number of essentially smaller basic particles, which particles are coated with the aqueous solution by its absorption in the stone's pores. 54. Method according to claim 23, characterized in that the clay is in the form of crushed stone which forms agglomerated particles, each of which contains a number of substantially smaller basic particles, which particles are coated with the aqueous solution by its absorption in the stone's pores. 55. Method according to claim 36, characterized in that the clay material is in the form of crushed stone which forms agglomerated particles, each of which contains a number of substantially smaller basic particles, which particles are coated with the aqueous solution upon its absorption in the stone's pores.