EP1513780A1

EP1513780A1 - A product for the protection of refractory materials

Info

Publication number: EP1513780A1
Application number: EP03709747A
Authority: EP
Inventors: Antonio Palumbo; Alberto Catania
Original assignee: Henkel AG and Co KGaA; Beaumont Italia Srl
Current assignee: Beaumont Italia Srl; Henkel AG and Co KGaA
Priority date: 2002-03-13
Filing date: 2003-03-04
Publication date: 2005-03-16
Also published as: NO20034586L; CN100441540C; BR0303386A; PL205514B1; PL372348A1; AU2003214094A1; ITTO20020217A0; CN1639083A; ITTO20020217A1; WO2003076357A1; NO20034586D0; WO2003076357B1

Abstract

A product intended for use in the protection and the possible repair of refractory materials, composed of alkaline salts of silicic and/or metasilicic acid, of fluxes and of refining products. The fluxes include fluxes derived from alkaline metals and hardening fluxes derived from boron, more particularly, the fluxes derived from alkaline metals may be sodium and/or potassium carbonate, and the hardening fluxes derived from boron may be boric acid or sodium borate. The refining products may consist in sodium sulphate. The product is intended mainly but not exclusively for the treatment of refractory materials in the coke ovens.

Description

DESCRIPTION

A PRODUCT FOR THE PROTECTION OF REFRACTORY MATERIALS

The subject of the present invention is a product intended for use in the protection and the repair of refractory materials, particularly but non exclu- sively the refractory materials of coke ovens.

In the practice of coke ovens, the refractory materials forming the walls and the top horizontal channel are subjected to be damaged by the thermal stresses and by the abrasion exerted by the coke, especially when it is taken out of the oven. The results are particularly a wear of the refractory materials and the crop up of fissures, with the ensuing need to proceed to repairs. Moreover, during the operation of the ovens takes place a deposition of graphite, which should be removed. These phenomena, even when they do not involve the need for a premature replacement of the refractory materials, often compel to stop the oven operation during periods, which on the average are of 3 to 4 days, devoted to the repairs and the cleanings, thus heavily weighing on the operating expenses of the ovens.

The damage of the refractory materials also has the consequence of a discharge from the chimney, and consequent diffusion in the environment, of polluting powders, coke gas and aromatic polynuclear hydrocarbons. Presently, the wear and the fissures of refractory materials are repaired by using three methods: the atomization of refractory material, the spraying of cement material along with water (so called cement gun), and the ceramic welding.

The first method, consisting in atomizing refractory material, has the drawback of a very limited duration of the repair thus made.

The second method, the cement gun, is only suitable for the temporary repairs of the exterior sections of the ovens.

The third method, consisting of the ceramic welding, results in repairs considerably more effective and durable than those obtained by either formerly mentioned methods, and allows to effectively repair the more evident fissures, however it requires a costly intervention and the removal of refractory material from the walls. No one of these methods, which only serve to make repairs, has the effect of improving the subsequent resistance to the damages of the refractory materials. There is presently known in commerce no powdery product intended to the treatment of refractory materials in order to increase their resis- tance to damages.

The problems discussed above are characteristic of the refractory materials used in the coke ovens, however similar problems are presented by refractory materials used in other applications too.

Therefore, a first object of the present invention is to develop a prod- uct suitable for being applied onto refractory materials in order to improve their resistance to some causes of damage.

Another object of the invention is to develop a product which, when applied onto refractory materials, should also be suitable for repairing some damages or defects. Still another object of the invention is to develop, such a product whose application onto refractory materials does not involve problems and may be effected by simple operations of low cost.

Finally, an object of the invention is to develop such a product whose manufacture does not involve technological difficulties, is of low cost and does not require the use of substances which are costly, are difficult to be found or involve dangers for the workers or for the environment.

According to the invention, the product intended for use in the protection and the repair of refractory materials includes alkaline salts of the silicic and/or metasilicic acid, fluxes and refining products. Preferably, the fluxes include fluxes derived from alkaline metals and hardening fluxes derived from boron.

The function of the alkaline salts of silicic and/or metasilicic acid is of forming, at the surface of the refractory materials onto which the product is applied, a vitreous or ceramic layer having a high hardness. This layer effec- tively protects the refractory material from the wear by abrasion, reduces the friction coefficient with respect to the coke, thus reducing the resistances when the coke is taken out of the oven, and is suitable for obstructing, and therefore repairing, at least the minor fissures. The function of the fluxes is to render more easy and uniform the building up of said vitreous or ceramic layer, and the fluxes derived from boron also have the function of increasing the hardness of said vitreous or ceramic layer. The function of the refining products is to suppress or reduce the dishomogeneity of the components in the building up of said vitreous or ceramic layer.

Preferably, the alkaline salts of the silicic and/or metasilicic acid have a weight ratio between alkali and silica from 1 to 3. Preferably the fluxes derived from alkaline metals are sodium and/or potassium carbonate.

Preferably the hardening fluxes derived from boron are boric acid or sodium borate.

Preferably the refining products include sodium sulphate. Preferably the alkaline salts of silicic and/or metasilicic acid are included in the product in a weight ratio from 30% to 60%, and more preferably from 45% to 60%.

Preferably the fluxes derived from alkaline metals are included in the product in a weight ratio from 10% to 25%, and more preferably from 10% to 20%.

Preferably the hardening fluxes derived from boron are included in the product in a weight ratio from 10% to 30%, and more preferably from 10% to 25%.

Preferably the refining products are included in the product in a weight ratio from 3% to 10%, and more preferably from 5% to 7%.

As it may be remarked from the foregoing, the product according to the invention does not involve the use of components which are costly, are difficult to be found or may produce damages to the persons or to the environment. It may be applied onto the refractory materials by atomization, using the techniques and the apparatuses already known and available for the atomization of other products, and without incurring any special difficulty.

After the application of the product according to the invention, during a suitable heating to be effected before resuming the operation, on the refractory material is built up a vitreous or ceramic layer which is glossy, has a high hardness, a high thermal and mechanic resistance and a low friction coefficient; it obstructs and repairs at least the minor fissures and protects the entire exposed surface of the refractory materials, thus noticeably increasing their useful duration and drastically reducing the interventions for repairs. Due to the fact that the surface of the refractory materials is left glossy, ensues a reduction of the stresses when the coke is taken out of the oven, and from the reduced damage of these materials ensues a high reduction in the discharge of powders from the chimney. Moreover the vitreous or ceramic layer produced has a scarce adhesion with respect to the graphite, and consequently the deposition of graphite is reduced and also reduced is the need of interventions for its removal, which is rendered more easy.

In order to better clarify the invention, some examples of preferred embodiments thereof are described in the following.

Example No. 1. The detailed composition of the products of this example is as follows: Pentahydrate or anhydrous sodium metasilicate having a weight ratio alkali/silica 1 :1 58 %

Boric acid 15 %

Potassium carbonate 20 % Sodium sulphate 7 %

With this composition, very good results are obtained when effecting the heating before resuming the operation by means of a thermal cycle comprising a first heating during 10 hours at 1200 °C (temperature at the burners) then a heating during 4 hours at 1000 °C and finally a heating during 6-8 hours at 1200 °C.

Example No. 2. The detailed composition of the products of this example is as follows: Sodium or potassium silicate having a weight ratio alkali/silica 1 :2 60 % Sodium borate 20 %

Potassium carbonate 18 %

Sodium sulphate 5 % With this composition, very good results are obtained when effecting the heating before resuming the operation by means of a thermal cycle corresponding to that stated in Example No. 1.

Example No. 3. The detailed composition of the products of this example is as follows: Sodium or potassium silicate having a weight ratio alkali/silica 1 :3 54,0 %

Sodium borate 25,0 %

Potassium carbonate 15,5 % Sodium sulphate 5,5 %

With this composition, very good results are obtained when effecting the heating before resuming the operation by means of a thermal cycle comprising a single heating during 24 hours at a temperature of the walls of at least 900 °C (temperature at the burners of 1000 to 1050 °C).

Of course, the stated components may be replaced by other components being technically equivalent, and the thermal cycles stated are the preferred ones but they may be replaced by other thermal cycles suitable for producing similar phenomena in rendering vitreous or ceramic the layer formed by the product. It is to be understood that the invention is not limited to the described embodiments. Several changes are possible for those skilled in the art, especially by replacing some components with technically equivalent ones and by possibly adding further components, as well as by modifying the thermal cycle applied to the product before the operation is resumed. These changes may be introduced in what has been described without departing from the spirit of the invention as stated in the Claims.

Claims

1 . A product intended for use in the protection and the possible repair of refractory materials, characterized in that it includes alkaline salts of the silicic and/or metasilicic acid, fluxes and refining products.

2 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the fluxes include fluxes derived from alkaline metals and hardening fluxes derived from boron.

3 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the alkaline salts of the silicic and/or metasilicic acid have a weight ratio between alkali and silica from 1 to 3.

4 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the fluxes derived from alkaline metals are sodium and/or potassium carbonate.

5 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the hardening fluxes derived from boron are boric acid or sodium borate.

6 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the refining products include sodium sulphate.

7 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the alkaline salts of silicic and/or metasilicic acid are included in the product in a weight ratio from 30% to 60%, and preferably from 45% to 60%.

8 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the fluxes derived from alkaline metals are included in the product in a weight ratio from 10% to 25%, and preferably from 10% to 20%.

9 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the hardening fluxes derived from boron are included in the product in a weight ratio from 10% to 30%, and preferably from 10% to 25%.

10 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in Claim 1 , characterized in that the refining products are included in the product in a weight ratio from 3% to 10%, and preferably from 5% to 7%.

1 1 . A product intended for use in the protection and the possible re- pair of refractory materials, as set forth in one or more of the foregoing

Claims, characterized by a composition at least approximately corresponding to the following one:

Pentahydrate or anhydrous sodium metasilicate having a weight ratio alkali/silica 1 :1 58 % Boric acid 15 %

Potassium carbonate 20 %

Sodium sulphate 7 %

12 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in one or more of the foregoing Claims, characterized by a composition at least approximately corresponding to the following one:

Sodium or potassium silicate having a weight ratio alkali/silica 1 :2 60 %

Sodium borate 20 % Potassium carbonate 18 %

Sodium sulphate 5 %

13 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in one or more of the foregoing Claims, characterized by a composition at least approximately corresponding to the following one: Sodium or potassium silicate having a weight ratio alkali/silica 1 :3 54,0 %

Sodium borate 25,0 %

Potassium carbonate 15,5 % Sodium sulphate 5,5 %

14 . A product intended for use in the protection and the possible repair of refractory materials, as set forth in one or more of the foregoing Claims, characterized by its particular destination to refractory materials of coke ovens.

15 . A product intended for use in the protection and the possible repair of refractory materials, characterized by the peculiarities, components and compositions, as they appear from the foregoing specification or replaced by technically equivalent means and possibly added with further components.