US2231498A - Mortarless masonry - Google Patents

Description

Fe 1941- w. GEISTLER 2 231 MORTARLES S MAS ONRY Filed Feb. 27, 1959 Patented Feb. 11, 1941 PATENT OFFICE MORTARLESS MASONRY Wilfried Geistler, Ra'dentheln, Carinthia, Germany, assignor to Oesterreichische Magneslt Aktiengesellschaft,

Radenthein,

Carinthia,

- Germany, a joint-stock company Application February 27,1939, Serial No. 258,796 In Austria March 3, 1938 14Ciaims.

This invention relates to mortarless masonry, more particularly to mortarless masonry built up of refractory bricks, especially basic bricks, with spacing pieces of metal inserted in the joints between the bricks, such as brickwork linings of revolving cylindrical kiln or rotary furnaces.

An object of this invention is to provide mortarless masonry that, has a considerable strength owing to stresses due to expansion of the bricks during the'heating operation being avoided.

A further object of this invention is to provide spacing pieces of metal that are particularly suited for the'purpose aimed at.

Further objects will appear as the description proceeds.

In the erection of furnace masonry or brickwork which is not free to expand, such as the arches of hearth furnaces and the brickwork fin ings of revolving cylindrical kiln, or rotary furnaces provision must be made for preventing the occurrence of excessively high stresses due to the heat expansion of the bricks. With this object in view it has already been proposed to insert between the bricks flat pieces of sheet metal, which keep the bricks, when settling, spaced apart at the distance required for equalising the heat expansion and which subsequently soften, when the furnace is being heated up. For brickwork composed of magnesite bricks and magnesia-containing bricks it has been proposed to use as spacing elements inserted in the joints pieces of sheet iron, which cause cementing of the bricks, the iron oxide produced in heating up combining with the magnesia of the bricks to form magnesium s5 ferrite. In carrying out these proposals in practice it has been found, however, that, when pieces of sheet metal are used as inserts, the brickwork cannot be reliably relieved of stresses-due to the heat expansion of the bricks, because, even at temperatures lying far below the melting point, more particularly during the slow heating up, an oxidation of the spacing elements takes place, a process which is combined with a considerable increase in volume and thereby further increases the stresses due to the heat expansion of the bricks. This disadvantage can also not be mitigated by the use of 'spacingelements of perforated sheets, which are also known.

Good results have been 'obtainedwith sheet 59 metal spacing elements having projections formed from the material. When'forinstance corrugated sheet .metal wth flat crests or waves on both sides are insertedbetween the bricks, .dan-

gerous-stresses cannot occur uring the heating 55 up period, as the corrugated t metals easily be very high surface pressures.

become flattened. As, however, the scale formation and consequent increase in volume continues after the flattening of the spacing elements, the

danger of an excessive stressing of the brickwork is not wholly eliminated. 5 According to the present invention there are used for the building up of mortarless brickwork from basic highly refractory bricks, metal grids,

the bars of which are narrow preferably like knife edges. Owing to this special formation the spac- 10 ing element is in contact with the bricks only in very narrow zones and consequently such high surface pressures develop already at the start; of heating up period, owing to the heat expansion of the bricks and the increase in volume of 15 the spacing elements, due to the oxidation, thatv the brick material becomes friable at the places of contact and the spacing elements cut into the side walls of the bricks. The stresses, to which the bricks are thereby exposed as a whole, are 20 however .very small. These stresses cannot reach an amount exceeding what is allowable, even in the further course of the heating up period, when the spacing elements become soft, as the grids consisting of thin bars offer only very little re- 25 sistance to crushing. In any case it is possible,

by suitably dimensioning the distance the bars of the grid are apart, on the one hand optionally to increase'the surface pressure at the places of contact with the bricks and on the other hand an "optionally to reduce the resistance which the softened grid ofiers to crushing.

Round wires are preferably used for making the grids. Spacing elements made of round wires are only in line contact with the bricks and there- .35 fore cause very high surface pressures to develop.

According to a preferred constructional form of the invention wire netting is used for the spacing elements. Whenwire netting is used, contact 40 will occur at points and there will consequently Owing to their great roughness wire netting will be held in a reliable manner in the joints of the brickwork and consequently, when used in arched brick- 45 work, it is unnepessary to provide means for preventing the spacing elements from'falling out of the brickwork. A further considerable advantageof the wire nets is. that the amount of material used is very small. As the wires of a netspectively through two bricks of a furnace lining ments at the crossing places of the wires is somewhat greater than the expansion of the bricks at the side facing the fire, in order that the bricks shallnot come in contact with one another at the end facing the fire. This arrangement causes the pressure to be transmitted to those parts of the bricks, which are remote from the fire, where, owing to the relatively low temperatures, there has been no softening of the spacing elements, which is of advantage in so far as the bricks are in these colder parts far more resistant to pressure stresses.

. Should the bricks become worn at the side facing the fire, the zone of high temperatures will be displaced towards the outside surface of the brickwork and the zones which have previously remained cooler will expand to a. greater extent. There is no risk however of dangerous strains occurring. As the wire netting inserts will have remained practically unaffected in the outer regions, the same effects will then occur at these places, which had occurred during heating up in.- the regions lying nearest to the fire.

On the furnace being put out of operation, the bricks will again contract, and thus the cement formed by the combining of the iron oxide produced from the spacing elements with the ma nesia of the bricks will be placed under tension. In the case of brickwork built up with the use of j sheet metal inserted in the joints the side walls of the bricks become cemented together over their entire extent and consequently very great forces are required for parting them at their cemented Joints. Should the cemented joint become loosened at one, place or another, the further contraction of the bricks will have effect only at these weakened parts of the joints. Consequently widely gaping joints will appear at few places only, which may cause a collapse of the brickwork, when the fire is started again. If however grids or pieces of wire netting be used as spacing elements or inserts in accordance with the invention, the cementing will be distributed in the manner of network. When a suitable size of mesh is used, a cemented joint formed in this manner will offer so little resistance that gaps will be formed at almost all abutting places, which are no wider than the joints which were present in the brickwork before heating up and therefore do not detrimentally affect the cohesion of the brickwork.

Embodiments according to this invention are with a wire netting inserted between the bricks. Fig. 8 shows a modification.

Referring to Fig. 8 and metal grid in a modification of the structure shown in Figs. 1 and 2, consists of bars I that are narrow like knife edges.

.Thegridmayalsobemadeofroundwireszas 'lol showninFig.3. Figs. 4 and illustrate a netting made from wires 3 for use as spacing element according to this invention. The spacing elements 3 are inserted in the joints 4 between the refractory bricks 5 asisshowninFigs. 6 and'l.

Fig. 8 shows in section, the bars I of a grid.

otherwise like the grid shown in section in Fig. 2, but the bars or strips I are sharpened at the edges, so that they will more readily press into the adjacent bricks. This sharpening preferably is done not only on the bars shown in section in Fig. 8, but also on those shown therein in elevation.

The metal of the spacing elements or inserts is oxidizable at high temperatures, and like its oxide is free from deleterious action on the refractory quality of the bricks. By the heating up step of the brickwork with the inserts in the joints, the bricks are caused to expand and thereby the metal of the inserts is pressed and penetrates at least partly into the body of the bricks, after which the metal of the inserts is softened and oxidation of the softened metalis allowed to occur. The metal oxide can be, in part at least, taken up by the refractory bricks without injury to the refractory qualities of the bricks.

In the erection of furnace arches with bricks built up with mortar, wire netting has already been used, in order to counteract the shrinkage of the mortar when heated. For obtaining this result, the wire netting 'must be embedded in the mortar, so that the effects obtained with the method according to the invention cannot result.

Josef Berlek showed in Patent 2,148,054, a corrugated sheet iron or a sheet of iron having struck up and struck down zones, to be used as a spacer in making brickwork of the kind here indicated. When the bricks are heated up and expand, pressure of the expanding bricks flattens out the corrugations or the struck up and struck down portions (or zones), whereas in the present invention, the expansion of the bricks forces themselves, the thickness of the grids and of the crossed wire portions of the wire netting not being reducible by pressure between the bricks.

According to the provisions of the patent'statutes, I have explained the principle and construction of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practised otherwise than as specifically illustrated and described.

I claim:

1. A method of building up refractory masonry in a furnace which comprises laying up refractory bricks without mortar filling the spaces between adjacent bricks, while leaving open spaces bethat edge of the bricks which will be next to the source of heat when the furnace is used, the metal of said structures being capable of becoming softened and oxidized at high temperatures, and said metal and its oxide being free from deleterious action on the refractory quality of said bricks, and heating up the thus built up brickwork assemblage suiliciently to cause expansion of the bricks and consequent reduction of the spaces between said bricks, and thereby at least partly pressing the said metallic structures into the adjacent surfaces of said bricks, and thereafter continuing the heating sufficiently to soften :the metal of said structures andto cause oxida- :ion of said softened metal while said metal is 2. A process as in claim 1, in which the said flat open-work metallic stru tures are composed of flattened strips having 'fe edges directed toward the adjacent bricks.

3. Method ofbuilding up refractory masonry, which comprises laying up refractory bricks without mortar,- leaving spaces between the said bri sufficient to allow for expansion of the bricks during a heating up step, filling the joint by file insertion of metal grids consisting of round wigs, the metal of said grids being oxidizable a? high temperatures, and said metal and its oxide being free from deleterious action on the refractory quality of said bricks, and heating the 7 thus built up brickwork, for causing expansion of the bricks and thereby at least partly pressing the mud wires of said metal grids into the body of the bricks, and thereafter softening themetal of said grids, and allowing oxidation of sai softened metal to occur. I

4. Method of building up refractory masonry, which comprises laying up refractory bricks without mortar, leaving spaces between the said bricks sufficient to allow for expansion of the bricks during a heating up step, filling the joints by the insertion of wire nettin the metal of said wire netting being oxidizable at high temperatures, and said metal and its oxide being free from deleterious action on the refractory quality of said bricks, and heating the thus built up brickwork, for causing expansion of the bricks and thereby at least partly pressing the wire netting into the body of the bricks, and thereafter softening the metal of said wire netting, and allowing oxidation of said softened metal to occur.

5. Method of building upa refractory brick lining in a metal walled metallurgical furnace,

which comprises laying refractory magnesia-containing bricks, without mortar between said bricks, as a lining in a metalwalled metallurgical furnace. while leaving suificient spaces between the bricks to allow for expansion of the bricks during the step of heating up the furnace to a temperature at which iron softens, and insetting iron grids into the joints between the bricks, said iron grids being constructed and arranged to cut into the'body of said bricks when said bricks expand by being heated, and heating the furnace structure thus built up, whereby firstly the expansion of the bricks, due to the heating, presses the iron grids into the expanding bricks, after which, upon heating to higher temperatures, the iron becomes softened and at least in part oxidized and iron oxide so formed reacts with magnesia of the bricks to form magnesia ferrite which can act as a cementing agent for cementing adjacent bricks together.

6. Method of building up a refractory brick lining-in a rotary furnace which comprises laying refractory magnesia-containing bricks, without filling the spaces between said bricks with mortar pansion of the bricks due tothe heating presses the wire netting into the expanding bricks, after which, uponheating to higher temperatures, the iron becomes softened and at least in part oxidizedand iron oxide so formed reacts with magnesia of the bricks to form magnesium ferrite which can act as a cementing agent for cementing adjacent bricks together.

'1. Furnace masonry which comprises refractory bricks laid with open spaces left between adjacent bricks sufiicient to permit expansion of the said bricks by heating, metal grid inserts in said which said inserts extend to the surfaceo'f-said bricks against which the heat in said furnace is directly applied, the. metal of said inserts,.bein g oxidizable at high temperatures, and said metal and its oxide being free from deleterious action on the refractory quality of said bricks,

and said metal grid inserts being adapted under the pressure of the expanding bricks to penetrate at least partly into the bricks during the step of heating up of said bricks and before the said metal inserts substantially soften due to high heat, such assemblage being capable of further heating sufficiently to soften and oxidize the metal inserts. r 8. Furnace masonry which comprises basic refractory bricks laid with open spaces left between adjacent .bricks sufllcient to permit expansion of the said bricks by heating, wire netting inserts located in said spaces, the metal of said inserts being oxidizable at high temperatures, and said metal and its oxide being free from deleterious action onlthe refractory quality of said bricks, and said wire netting being pressed into the bricks by the expansion of the same during the step of heating up of said bricks and before the said metal inserts substantially soften due to high ing the heat.

10. Method of building up refractory masonry,- which comprises laying up refractory bricks without filling the spaces between the bricks with mortar, thereby leaving spaces between the said bricks, suflicient to allow for expansion of the bricks during a heating up step, placing metallic spacers in the spaces, which spacers are in touch with the bricks, at a plurality of small zones only, which zones in all constitute a small fraction only of those faces of the bricks which face the joints and the effective thickness of said spacers at said small zones being non-reducible by pressure produced by the expansion of said bricks due to said heating, whereby upon heating said bricks the metal spacers are caused to substantially penetrate into said bricks at said zones,

the metal of said spacers being softenable and oxidizable at high temperatures, and said metal and its oxide being free from deleterious action on the refractory quality of said bricks, and heating the thus built up brickwork sufiiciently to cause expansion of the bricks and thereby at least partly pressing the spacers into the body of the bricks, and thereafter softening the metal of said spacers by further heating, and allowing oxidation of said softened metal to occur.

11. Method of building up refractory masonry, which comprises laying up refractory bricks without filling the spaces between the bricks with mortar, thereby leaving spaces between the said bricks suflicient .to allow for expansion of the bricks during a heating up step, inserting metallic spacers into said spaces, which spacers are in touch with the bricks, at a great number of Separate small zones, the combined areas of said small zones being a small fraction only of the area of a face of a brick adjacent to one of said spacers, said spacers while at temperatures below the softening point of the metal of which they are composed, being incapable, at said small zones, of substantial reduction in thickness by pressure of the expanding bricks during heating, and said spacers initially extending substantially to that surface of the bricks which faces the heat when heat is applied in normal manner in said furnace, the metal of said spacers being capable of softening and oxidizing at high temperatures,

and said metal and its oxide being free from deleterious action on the refractory quality of said bricks; and heating the thus built up brickwork sufliciently for causing expansion of the bricks and thereby at least partly pressing the spacers into the body of the bricks, and thereafter further heating sufliciently for softening the metal of said spacers, and allowing oxidation of said softened metal to occur.

12. A process as set forth in claim 1, applied to the step of lining with refractory brick, a cylindrical rotary furnace having a confining me- Itallic outer wall and constructed and arranged for internal heating.

13, A process as in claim 1, in which the said flat openwork metallic structures are constructed in the form of grids.

14. A. method of building up refractory masonry in a furnace which comprises layiny up refractory bricks without mortar filling the spaces between adjacent bricks, while leaving open spaces between adjacent bricks suflicient to allow for expansion of the bricks during a heat- I of the spaces between said bricks, and thereby at' least partly pressing the said metallic structures into the adjacent surfaces of said bricks, and thereafter continuing the heating sufficiently to soften the metal of said structures and to cause oxidation of said softened metal while said metal is hot.

WILFRIED GEISTLER.

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