DE738444C - Refractory body cast from the melt flow - Google Patents

Description

Refractory body cast from the melt flow The present The invention relates to cast refractory bodies for lining from the melt flow of glass furnaces, glass harbors or tubs. Refractory walls or lining parts that beire Melting - glass coming into contact with the melt flow. place as is well known the operation of glass furnaces, glass ports. or similar devices a certain 'Restriction to, as a result of their properties, the working temperatures and limit the operating performance accordingly.

In the vats of glass furnaces there must be good circulation and mixing of the melt flow take place in order to - the tendency of the melt to form streaks to belittle. However, the flow of the molten glass has in common Ovens have such a damaging effect on the usual refractories forming the lining Substances that stirring and mixing to the desired extent is not possible. In particular. the constant movement of the glass affects certain parts of the Tub; such as work openings, parts of the pull-out openings, partition walls, shaped blocks, which serve to separate the melting area from the working area, and shorten the Service life of such parts is considerable. The same applies to parts or objects which are moved through Glag, e.g. B. stirrer arms, rods, boats.

The present invention overcomes this disadvantage in that the relevant parts made of-at least 80% corundum "2% or more silica and i bis ioo; o alkali or alkaline earth compounds or mixtures thereof exist.

Refractory materials, consisting essentially of alumina and silica exist are known per se. It has already been suggested that such Must from the. To manufacture melt-flow cast refractories. It is also a crystalline alumina product known, which mainly contains beta clay, namely in amounts of -over 8: o%. Furthermore, it is also known to melt products made of clay, silica. and alkaline earth as a paint on the inner surfaces of To use melting vessels, but it was not yet known that from the Schinelzfiuß Cast bodies of the specified composition are particularly suitable. are; the corrosive Effect of the molten material in a glass melting tank or a melting furnace resist and significantly increase their lifespan.

These body parts prove to be particularly advantageous for such parts of ovens in which the signs of attack are most likely to appear step, z. B. on the surface of the molten glass. The same goes for the openings the loading doors and those parts that come into contact with the glass flow, when it is moved relatively strongly. .

The oxides of potassium come from the alkali compounds and sodium; of the alkaline earth compounds the oxides of calcium, magnesium and Bariums in question.

It has been shown that the addition of alkali to that of alkaline earth is preferable, so the use of sodium or potassium oxide or a Mixing these two substances is recommended.

Some examples are given below by way of illustration. I. (product) - 85 to 100% clay,. - i4% silica, i - io% sodium oxide or potassium . oxide or a mixture of suffering. II. (Approach) 94% bauxite, 6% sodium carbonate. III. (Approach) 97% clay mineral with a content of about 30/0 silica, 3 0, 'o barium carbonate. - IV. (Product) go% clay, 50/6 silica, 5% soda. Surprisingly, the material according to the invention is also extremely resistant to the effects of fluorine glasses; Since aluminum oxide is dissolved in a molten fluoride bath (cryolite) in the production of metallic aluminum, one should assume that fluoride glasses attack refractory materials according to the type of the present invention particularly strongly and quickly. However, this is not the case; on the contrary, blocks of alumina are finite one. Content up to 5% sodium oxide more resistant to attack by fluoride glass than any other known refractory material.

In the manufacture of refractory materials of the type described one proceeds in the following way: Alumina, usually in the form of bauxite or a other high-alumina mineral, is heated in an electric furnace such as that used in e.g. B. . is used in the manufacture of synthetic alumina finishes, melted.

. Soda, usually in the form of sodium carbonate, is either that original starting material is added or after the main amount is completely melted and after any reducible impurities such as iron oxide or silica, to the greatest possible extent. have been removed, in larger quantities with added to a special charge. The addition of soda makes the latter possible it is to regulate the proportion of silica in the finished melt. In general it should be desirable to keep the silica content within the specified limit low. to keep, because so in the end product the proportion: of crystalline clay and the proportion of inter-crystalline glass is reduced.

The furnace used for melting is generally water-cooled iron coat, without any lining other than that to be loaded is well provided. The melting process is initiated by an electric arc, later, the electrical resistance of the weld pool is sufficient to generate heat maintain. The melt is gradually and. after being filled. If the approach a particularly high content of undesirable additives, such as iron oxide, or if it contains too much silica, lump coke is used to reduce these substances added. However, the bath can also be reduced by the action of the electrodes. The reduced metal settles on the bottom of the furnace, where it ends up of the process and then withdrawn separately. In some cases it can it may be useful to remove the finely divided metal and to accelerate it des .Absetzens to put a metal, for example iron filings, in the furnace. the Further treatment takes place according to the type of clay abrasives production.

When the goods have reached the right degree of warmth and fluidity, it is poured into molds.

The formed pieces are allowed either in the forms of heat treatment or takes it, especially when you iron molds used from - the forms, and that shortly after the outer walls of the casting Video- solidified. They are then cooled in a known manner and then, if necessary, freed from burrs or other unevenness by grinding or machining.

Fireproof bodies of the type described are resistant to attacks of glass rivers so resistant that one can with about 100 ° higher temperatures in the Ovens can work, increasing the efficiency of the ovens considerably increased, the duration of the melting process accelerated and a proportionate rapid and effective glass movement is achieved.

But also with the operation of the ovens at the usual temperatures the bodies according to the invention prove to be extremely advantageous; ,because one refrains from cooling the outer walls or restricts this to a low level can; there. Damage to the walls is not to be feared. The possibility, Insulating the outer walls and switching off cooling, in turn, brings considerable benefits Savings with them, both by avoiding heat loss and in terms of acquisition and maintenance costs.

Claims (3)

PATENT CLAIMS: i. Refractory bodies cast from the Schinelz river for lining glass furnaces, vans or ports, which are mainly made of aluminum oxide and silica consist, characterized; that they are made of at least 8o / o corundum, 2% or more silica and 1 to rö% of an alkali or alkaline earth compound = young or mixtures thereof. 2. Refractory body according to claim i, characterized by a content of barium. 3. Refractory body according to claim @ i; marked by a content of 8 5 to 97% clay, 1 to 10% sodium oxide and 2 to - 140/0 silica.