US2764493A - Process for the production of refractory masses or bricks from slags - Google Patents

Description

United States Patent i PROCESS FOR THE PRODUCTION OF REFRAC- TORY MASSES OR BRICKS FROM SLAGS Karl Albert, Vogelbeck, Hannover, Germany No Drawing. Application May 14, 1952, Serial No. 287,810

1 Claim. (Cl. 106-55) The invention relates to a process for the production of highly refractory or refractory masses and/or bricks, all hereinafter called blocks.

It has been found that the resistance to wear, the durability and the resistance to change of temperature of such blocks can be considerably improved by comminuting slags which are poor in silicic acid (SiOz), especially those incorporating titanium and manganese, to the fineness of a flour up to a grain size of about .51, then mixing the same with a binder, such as wator-glass, moulding such mixture to the desired shape and compacting it by pressing or shaking, and then subjecting the moulded products or the mass for a number of hours to a heat treatment at temperatures of about 212-392 F. Suitable starting materials are the slags which contain the aforementioned high-melting point metals and small silicic acid content, and which occur in the crucible-steel process or in an electric furnace. Thermite slags of such composition may also be employed.

In the new cold-bonded slag blocks, the individual grains are connected together with the aid of the binding agent by adhesion. The internal relationship of the particles in the blocks is therefore very mobile. and can, on the subsequent insertion of the blocks in a furnace, adapt itself considerably better than the structure of calcined blocks to the heat stresses that act upon the surface of the smallest side of the blocks, since in calcined blocks, the individual granular constituents are fritted together by sintering, so that a rigid and not very yielding structure is produced. This fundamental difference between the structures of cold-bonded blocks and calcined blocks is substantially maintained when the blocks are used in industrial furnaces, since the blocks are exposed to high temperatures only on their sides exposed to the fire, whilst the heating effect falls off rapidly at the other side. The special advantages of the cold-bonded blocks, particularly their resistance to change of temperature and other advantageous properties, therefore remain unaltered in use.

Water-glass is employed as a binding agent for the basic material.

The cold-bonded blocks produced from titanium slags have proved to be particularly advantageous, since, in addition to high resistance to temperature changes, as well as improved durability and resistance to wear, they prevent the formation of scale to a very high degree. They are therefore especially suitable for lining parts of the furnaces which are exposed to the formation of scale, so that, according to the invention, they are employed especially for lining the annular zone of Lepol and other revolving furnaces as well as for lining the sintering zone of shaft furnaces for the production of cement. When these blocks are employed, the considerable disadvantages, which hitherto occurred in the zones mentioned owing to the formation of rings of scale, are eliminated. Presumably this may be attributed to the very low heat-conductivity of the cold-bonded titanium 2 slag blocks, which causes a constant shedding. ofthe scale formed, so, that they cannot give rise to the said rings of scale.

Example 1 Ferro-titanium slag, as it occurs in the Thermite proeess, and which has the following composition:

Water-glass is used as a binder.

Example 2 Slags of the following composition, which occur in the Thermite process, are employed:

Percent SiOz 0 to 5 A1203 54 i0 F6203 l 5 to 1'0 TiOz. 15 to 33 CaO 2 m7 MgO 2 to 7 The slags are comminuted to a mixture. having the aforesaid grain sizes, and mixed with 4 to 8% by Weigh of water-glass (d=l.350) as well aswater until the whole becomes mouldable, then compacted by shaking, pressing or stamping and subjected to a heat treatment for a period of several hours at 2l2-392 F. Blocks obtained in this way may be used for lining the ring zones of Lepol and other revolving furnaces as weli as the sintering zone of shaft furnaces for the production of cement.

Example 3 A manganese slag of the following composition is used to produce an extremely tough, wear-resistant, special block which is typified by a very high resistance to temperature variation in combination with highly refractory qualities:

Percent SiOz 1.5 to 3.5 A1203 61 to 63 F6203 1.0 to 2.3 M11304 10 to 14 CaO 14 to 16 MgO 5.0 to 10 BaO to 1 This slag is comminuted and made up in the following granular composition:

724' to .l2" 30 to 35%. up to .l2" 35 to 70% including flour 25 to 30%.

The mixture thus obtained is mixed with approximately 7 per cent by weight of water-glass (d=l.350) and the quantity of water required to make it plastic, and is formed into blocks by agitation or tamping. The moulded bodies obtained are brought to bonded condition by a heat treatment, in which the temperature rises to 392 F., lasting for a period of about 24 hours.

The blocks produced are of high refractory quality besides possessing a very good cold compressive strength and. heat resistance.

Example 4 A mixture of two manganese slags, differing in their chemical compositions, are used to manufacture a block which is particularly suited for use in rotary furnaces. The first manganese slag (hereinafter referred to as slag I) has: the composition:

Percent SiOz 1.5 to 3.5 A1203 61 to 63 FezO: 1.0 to 2.3 MnaO4 to 14 CaO 14 to 16 MgO 5.0 to 10 BaO to 1 and is mixed in equal parts with the second slag (slag ulation set out in Example 1, mixed with approximately 6% water-glass (d=1.350) and the quantity of water required to render it plastic, moulded into blocks by shaking or tamping, and these blocks bonded by heating the blocks to a maximum temperature of 392 F. for 'a period of about 24 hours.

In comparison with the properties of the product of Example 1, the blocks here produced have, as befits their intended use, an even higher refractoriness, heat resistance and toughness.

I 2 Example 5 whole or partial replacement of the finely-divided components of a mixture of slags of the composition and granular constitution of Example 4 by titanium slags in flour form, a special block of great resistance to wear and breakage and to temperature variation is obtained.

To produce such a block the manganese slags described in Example 4 are mixed in equal proportions, the mixture comminuted, and mixed with finely-divided titanium slag in approximately the following composition:

Percent .24 to .12 1 30 to 35 up to .12 112 35 to Flour 3 10 to 15 1 Mixture of equal parts of manganese slags I and II. Including 10 to 15% flour. 3 Titanium slag.

Added to this mixture are at least 7 per cent by weight of water-glass (d=1.350) and the quantity of water re quired for plasticity, and the composition moulded into blocks and bonded as described above. The blocks thereby obtained have an even greater wear and breakage resistance and heater refractory quality than those produced in Examples 1 and 2, and a high degree of resistance to temperature variation. These attributes are achieved in augmented form if the whole of the flour component is replaced by a flour of titanium slag.

I claim:

A method of manufacturing refractory masses and blocks, consisting of the steps of so comminuting high softening and melting temperature slags of the type derived from the production of titanium in an electro furnace and by the alumino-thermic reaction of titanium ores and consisting of up to 5% SiOz, 54 to A1203, 15-33% TiOz, 1.5-10% FezOs, 2-7% Ca(), and 27% MgO as to make said slags contain about 30% of a coarse component of .24" to .12 grain size, about 40% of a medium component of less than .12" grain size, and about 30% flour; mixing said comminuted slags with 4 to 8% by weight of waterglass having a density d=1.350 for elastically bonding the slag particles and water in a quantity suflicient to bring the mixture into a moldable state; compacting said mixture; and heating said mixture for a period of several hours at temperatures of 212 F. to 392 F.

References Cited in the file of this patent UNITED STATES PATENTS 529,450 Kirchmann et al Nov. 20, 1894 1,094,876 Carson Apr. 28, 1914 1,244,688 Becket Oct. 30, 1917 1,462,991 Taylor July 24, 1923 2,252,317 Goldschmidt Aug. 12, 1941 FOREIGN PATENTS 908 Great Britain 1878 119,101 Great Britain 1918