US1877138A - Process of bloating and annealing cellular blocks - Google Patents

Description

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' PROCESS OF BLOATING AND ANNEALING CELLULAR BLOCKS Filed July 21, 1930 Patented Sept. 13, 1932 f UNITED STATES PATENT OFFICE SHERMAN '2.- LEE A1\TD'WAR1\TER H THAW Y, E MAn soN, wIsCoNsIN, SAID LEE AssICNoR, BY MESNE ASSIGNMENTS, CE HIS ENT RE RIGHT To AMERICAN EACE BRICK RESEARCH CORPORATION, A CoREoRATIoN 0E ILLINoIs ,PROGESS OF BLOAT'ILTG AND ANNEALING CELLULAR BLOCKS Application filed July 21,

This invention relates to process of bloating and annealing cellular blocks.

This invention is directed to a process of treating argillaceous or similar earthy materialwhile in granular form, to a heating and annealing treatment for the purpose of producing building-blocks and units or other articles of manufacture.

The product produced by the, process of 19 the present invention possesses high insulating qualities and isentir'ely impervious to moisture, and at the same time possesses suflicientstrength to easily meet building require- .ments. A

The material is'of a cellular or vesiculated character throughout, having a structure very similar to that of baked bread, and is of such light weight that'it readily floats in water and isotherwise well adapted for building pur- 20 poses. The process of the present invention includes a preheating step which is preferably formed under agitation in a rotary kiln, a bloating step whichis performed in a furnace or kiln affording a heat zone which will ordinarily be held at a temperature of approximately 2200 F., and an annealing step, to which latter in particular the present invention relates.

It has been ascertained that after the granular material has been fused and bloated by the formation throughout of minute cells or cavities, and after ithas assumed its ultimate dimensions, great care must be exercised in the annealing of the bloated productin order to prev'entit from becoming fractured -or shattered by the internal stresses incident to the-cooling-of the product down to room temperature. I q

Whilethe material is in the bloating stage, it is in a fused condition and somewhat plastic or pliable, but it has been found that when the temperature islowered by a comparatively small amount below the temperature of the bloating zone, a critical stage is reached at which the material congeals or solidifies, so that-immediately thereafter it becomes brittle and incapable of deformation, and unless it is handled with care during the annealing 1930. Serial No. 469,614.

period it will develop cracks or fractures which render it unfit for the intended purpose. In order, therefore, to properly anneal the material, it is necessary to divide the annealing period into two stages, which may be 53 referred to as the soaking stage and the cooling stage. During the soaking stage, the material, after its emergence from the bloating zone, is maintained at a temperature below that of the bloating zone, and which in pracso tice has been found to approximate from 2000 F. to 2050 F, The bloated material should be maintained in the soaking tempera- ,ture from one and a half to two hours under ordinary conditions, although both the bloat- 6B in g temperature and the soaking temperature may vary somewhat, depending upon the nature of the materials employed and the dimensions of the product subjected to treatment, the temperatures and times given being those appropriate to the production of a four inch thick slab bloated from certain clays from central and eastern Illinois, and serving for purposes of illustration only.

In all cases, the material should be held at a soaking temperature, which is intermediate between the bloating temperature at which the material continues actively to expand and the critical temperature at which the material congeals. Within the soaking zone, there- 30 fore, the bloating will be arrested, but the material will be maintainedin a slightly plastic or fluid condition during a suflicient period of time to permit all of the internal strains or stresses to be disseminated throughout the mass and thus dissipated by the complete equalization of the temperature throughout,

so that these strains or stresses will be eliminated before the material is'introduced into the cooling zone and subjected to a progressively diminishing temperature.

It is important, however, during the cooling stage of the process to-subject the material to a gradual decreasing temperature, partly in View of the fact that the bloated cellular material possesses high heat insulating properties, so that any sudden diminution in temperature will tend to cool the surface much more quickly than the interior, with a consequent tendency to shatter, due to inequalities in the rate of contraction throughout the mass.

By properly regulating the period of time devoted to the soaking stage, and by properly regulating the heat gradiant during the cooling stage, the bloated material will be properly annealed, so that when ultimately discharged from the annealing chamber itw'ill be free from cracks or fissures, and from internal strains which might tend later to develop cracks when the material is employed for building purposes.

In order to describe more in detail the technique observed in carrying out the present process, the various steps will be described as performed ina kiln, which illustrates diagrammatically a suitable apparatus for the performance of the process, although it will, of course, be understood that the apparatus shown serves merely for purposes of illus-- tration.

The drawing illustrates a longitudinal sectional view of a kiln comprising a bloating chamber 1, a soaking chamber 2, and a cooling chamber 3. As shown, the bloating chamber is of boxlike formation, and the soaking chamber and the cooling chamberare separately formed in an elongated extension,to which the material is fed either by continuous or intermediate movement from the bloating chamber to the point of discharge.

The bloating chamber is provided on its roof with a hopper 4 which discharges granular earthy material through an orifice 5 onto the bed or hearth 6 of the bloating chamber. Adjacent to the hopper 4 is a hopper 7 Which is adapted to discharge a lubricating .material, such as sand, graphite or the like, through an orifice 8.

A preheater, in the form of a rotary kiln 9, is obliquely mounted, and has its discharge end entered into the hopper 4. Within the preheater, the granular material is heated to a temperature which will ordinarily be in the neighborhood of from 1500 F. to 1800 F., the desire being to preheat the material to a pointbut slightly below that at. which the particles begin .to fuse or adhere together, so that the material will be delivered to the hopper 1 from the preheater while still in a granular condition.

The preheated material is spread out in the form of a layer by the use of a suitable charging device,o and for purposes of illustration a charger 10 is shown, which is in the form of an obliquely mounted plate having side walls or fianges, which plate is positioned to descend in an oblique direction through an opening 11 in the wall of the bloating chamber and is adapted to be actuated by suitable mechanism, such, for instance, as a rack and pinion12, operable from a point outside of the bloating chamber. Y

In charging the material onto the fioor or hearth of the furnace, the charging plate is thin layer over the hearth of the bloating chamber. Thereafter the charging plate is again introduced into the bloating chamber and receives a charge of granular material which is uniformly distributed and laid upon a sand bed, which bed is utilized for the purpose of preventing adherence of the bloating material to the hearth of the furnace.

The bloating chamber will under ordinary circumstances bemaintained at a temperature of approximately 2200 F., and the preheatedgranular material is allowed to remain in a quiescent or undisturbed state for a period sufficient to cause fusion or coalescence of the granular particles into a mass which while in plastic state'will be bloated by the formation of cells occasioned by the expansion of gases contained in the material.

The bloating stage will continue until the mass has been thoroughly bloated, which will ordinarily occupy a period of fromonehalf to three-quarters of an hour, although the period may vary considerably, depend-- ing upon the nature of the materials employed, the thickness of the layer deposited upon the hearth of the bloating chamber, and the amount of gas-forming constituents present within the mass. Also, the bloating period may be increased or diminished to the degree required to secure the intended density. In all cases, the bloatin will continue until the mass has been thoroughly fused, and the granular particles have com pletely coalesced together in the formation of a cellular block having the cells formed of vitrified material.

After the bloating stage has been complet ed, the material is discharged from the bloating chamber by any suitable means, such, for

instance, as a pusher 13 operated by rollers 14, and where acontinuous slab or column of material is being formed, the feeding movement can be assisted by the provision of draw rollers 15 located as shown in the cooling chamber 3. Furthermore, if desired, the bloated material can be subjected to a rolling process while still within the bloating chamher, by the provision of a roll 16, which is suitably manipulated to roll across the surfaceof the bloated slab and press down or even out any inequalities in the surface .of

the slab. The mechanisms shown, however,

serve merely for purposes of illustration, since numerous variations in the form and arrangement in the various mechanisms can be introduced without departing from the spirit of the invention.

The bloated material is discharged into the soaking chamber 2 wherein the temperature is maintained at a point intermediate to two hours, although of course the soaking time will depend on various factors, such for instance as the nature of the ingredients employed, and the thickness and density of the bloated slab.

Where the material is fed forward in the form of a continuous slab or column, the

- soaking chamber will be given an adequate ,for subsequent use.

length to permit the material to remain within the soaking zone for the required length of time, but where individual sections or disconnected units are bloated, the soaking chamber can be of suitable dimensions to permit an accumulation of such sections or units and they can be individually withdrawn from the soaking chamber after the soaking stage has been completed.

During the soaking stage, the bloated slab or slabs will be maintained while in a semiplastic condition until the temperature of the slab has been equalized throughout and until all internal strains or stresses have been properly distributed and equalized, and thereafter the slab or slabs will be introduced into the cooling chamber, which is preferably constructed to provide for a variably decreasing temperature, so that as the.

slabs are advanced through the cooling chamber they will be gradually cooled, without, however, permitting violent temperature changes, so that throughout the temperatures at the surface and within the interior of the mass will be maintained substantially equal, with the result that violent strains or stresses are avoided.

After the slabs have been cooled down to room temperature, they are delivered onto ,a platform or table 17 where they may be sawed into blocks or units by the action of saws 18 and 19, or otherwisermanipulated The slabs or blocks of material produced in the manner above described possess a substantially uniform cellular structure through out without inter-communicating pores, in-

terstices or crevices, and when properly treated the material will have a clear metallic ring, which in conjunction with its ability to withstand severe blows indicates its freewithout discernable joints or points of juncture. However, the invention is'not limited to the formation of the sections'in the form of units thus bloated and fused together, since the process may, by constant accretions or small amounts of material, be deposited at the terminus of the bloating mass, or"- if desired the material may be spreadin the form of superposed layers and bloated in this manner.

The present invention is therefore directed mainly to the treatment of the block, slab or continuous column, after it has been bloated in any suitable or desirable manner and during the annealing period, which as before stated is divided into the soaking stage and cooling stage.

' or purposes of adequate illustration, the soaking chamber and the cooling chamber are shown as separate and distinct portions of the @structure, but it will be understood that these chambers might under some conditions be merged together, provided only that the material is maintained at a substantially uniform soaking temperature for the 5 required length of time, and before it is carture maintained in the respective region than to any particular physical structure which is provided for'afiording or maintaining the zones in question.

It will also be understood that the material may be textured or colored in various ways during its period of treatment, but these details form no portion of the present invention, and need not be described herein.

We claim:

1. The process of treating earthy material in the production of a cellular mass, which consists in subjecting the material while under agitation to a temperature not exceeding that at which the particles retain their granular condition, continuing the heating at a higher temperature and with the material in a non-agitated condition to produce bloating to the desired dimensions, and continuing the heating at a soaking temperature intermedi ate the temperature at which active bloating occurs and the congealing temperature, for a sufficient period-of time to eliminate internal strains, and finally in gradually cool ing the -material.

2. The process of treating broken up earthy material in granular form, which consists in subjecting a layer of such material to a bloating temperature suflicient in-de'gree to cause fusion of the mass and bloating by liberation of internal gases, thereafter subjecting the bloated mass to a soaking temperature intermediate the bloating temperature and thecongealing temperature to permit the dissipation of strains and stresses throughout the mass, and thereafter gradually cooling the mass. 7

3. The process of treating broken up earthy material in granular form, which consists in subjecting a layer of such material to a bloating temperature sufficient in degree-to cause fusion of the mass and bloating by the liberation of internal gases thereafter subjecting the bloated mass to a soaking temperature intermediate the bloating temperature and the congealing temperature to permit the dissipation of strains and stresses throughout the mass, and thereafter cooling the mass at a rate sufliciently gradual to maintain substantial uniformity of temperatures at the surface and in the interior of the mass to prevent shattering due to excessive inequality in the distribution of'temperatures.

4. The process of treating broken upearthy material in granular form, which consists in first preheating the material under agitation to a temperature not exceeding that at which the particles retain their granular condition, then in subjecting a layer of such material to a bloating temperature suflicient in degree to cause fusion of the mass and bloating by the liberation of internal gases, thereafter subjecting the bloated mass to a soaking temperature intermediate the bloat-- ing temperature and the congealing temperature to permit the dissipation of strains and stresses throughout the mass, and thereafter gradually'c'ooling the mass.

5. The process of treating broken up earth material in granular form, which consists in first preheating the material under agitation to a temperature not exceeding that at which-the particles retaintheir granular condition, then in subjecting a layer of such material .to a bloating temperature suflicient in degree to cause fusion of the mass and,

bloating by the liberation of interial gases; thereafter subjecting the bloated mass to a soaking temperature intermediate the bloating temperature and the congealin g tempera-" ture to permit the dissipation of strains and stresses throughout the mass, and thereafter cooling-the mass ata rate sufficiently gradual ing successive charges of the material into a bloating zone at a temperature adapted to to maintain substantial uniformity of temperatures at the surface and in the interior of the mass to prevent shattering due to excessive inequality in the distribution of tem peratures. j v

6. The process of producing cellular bloated units of exact dimensions from earthy material, which consists in introducfuse the particles of each charge and produce a bloated mass, each succeeding charge being fused and bonded to the preceding bloated g a bloating zone at a temperature adapted to fuse the particles of each charge and produce h a bloated mass, each succeeding charge being fused and bonded to the preceding bloated mass to produce a continuous column, subjecting the bloated material to a soaking temperature intermediate the bloating temperature and the congealing temperature to eliminate internal stresses, and thereafter subjecting the material to gradual cooling to prevent shattering from temperature shock.

8. The process of producing a cellular mass adapted for building purposes, from earthy material, which consists in introducing layers of substantially uniform thickness of the material into a bloating zone at a temperature adapted to fuse the particles and produce a bloated mass of cellular material, discharging the material from the bloating charging the material from the bloating zone to a cooling zone and subjecting the material to gradual cooling at a rate sufficient to prevent shattering from temperature shock.

9, The process of producing a cellular mass adapted for building purposes, from earthy material, which consists in preheating the material in granular form, introducing layers n of substantially uniform thickness of the preheated material into a bloating zone at a tem-' perature adapted to fuse the particles and produce a bloated mass of cellular material, discharging the material from the bloating zone into a soaking zone maintained at a temperature slightly below thev bloating tempera- 1 ture and slightly above the congealing temperature, and retaining the material in the I soaking zone for a suflicient length of time to eliminate internal stresses, and thereafter discharging the material from the bloating zone to a cooling zone, and subjecting the material to gradual cooling at a rate sufficient to prevent shattering from temperature shock.

10. The process of producing a cellular granular product from earthy material,

which consists in preheating the material in granular form at a temperature of from 1500 F. to 1800 F., introducing charges of I 2200 F., and retaining mation of said preheated material into a bloating zone maintained at a temperature of substantially the material therein for a suflicient period of time to fuse the particles of each charge and produce a bloated cellular mass, introducing the mass into a soaking zone maintained at atemperature of approximately 2000 F. for a sufficient period of time to eliminate internal stresses, and thereafter gradually cooling the material to room temperature.

11. The process of producing a cellular mass which consists in introducing a charge of e'arthy material into a bloating zone at a temperature adapted to cause fuslon of the earthy material and expansion due to the for: mation of cells throughout the mass, and in thereafter subjecting the bloated mass to a soaking temperature intermediate the bloating temperature and the congealing temperature to eliminate internal stresses, and thereafter cooling the mass.

12. The process of producing a cellular mass which consists in introducing a charge of earthy material into a bloating zone at a temperature adapted to cause fusion of the earthy material andexpansion due to the forcells throughout .the mass, and in thereafter subjecting the bloated mass to a soaking temperature intermediate the bloating temperature and the congealing temperature to eliminate internal stresses, and thereafter cooling the mass at a sufliciently gradual rate to prevent shattering due to variations in contraction occasioned by abrupt surface cooling.

13. The process of treating earthy material in the production of a cellular mass, which consists in subjecting the material to a temperature not exceeding that at which the particles retain their granular condition, continuing the heating at a higher temperature and with the material in a non-agitated condition to produce bloating to,the desired dimensions, and continuing the heating at a soaking temperature intermediate the temperature at which active bloating occurs and the congealing temperature, for a sufficient period of time to eliminate internal strains, and finally in gradually cooling the material.

14. The process of treating broken up earthy material in granular form, which consists in first preheating'thematerial to a tem- 15. The process of treating broken up earthy material in granular form, which consists in first preheating the material to a temperature not exceeding that at which the particles retain their granular condition, then in subjecting a layer of such material to a bloating temperature sufficient in degree to cause fusion of the mass and bloating by the liberation ofinternal gases, thereafter subjecting vthe bloated mass to a soaking temperature intermediate the bloating temperature and the congealing temperature to permit the dissipation of strains and stresses throughout the mass, and thereafter cooling the mass at a rate sufficiently gradual to maintain substantial uniformity of temperatures at the surface and in the ,interior of the mass to prevent shattering due to excessive inequality in the distribution of temperatures.

In witness that we claim the foregoing we have hereunto subscribed our names this 27th day of June, 1980.

, SHERMAN Q. LEE.

WARNER HATHAWAY.

perature not exceeding'that at which the particles retain their granular condition, then in subjecting a layer of such material to a bloating temperature sufficient in" degree to cause fusion vof the mass and bloating by the liberation of internal gases, thereafter subjecting the bloated mass to a'soaking temperature intermediate the bloating temperature and the congealing temperature topermit the dissipation of strains and stresses throughout the mass,- and thereafter gradually cooling the mass.

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