US1811314A - Refractory material - Google Patents

Description

Patented June 7 23, 1931 FFHQE "roan nonnn'r Bantam). or STOCKHOLM, swnnmv REFRACTORY MATERIAL Ito Drawing.

Original application med. November 12, .1927, Serial No. 232,947, and in Germany June 4,

1927. Divided. and this application'filed'october 6, 1928. Serial No. 310,917.

Thisinvention relates to a fused refractory material having as essential compo-. nents oxides of magnesium and aluminum. This application is a division of my copending application Serial No. 232,947 of 'November 12th, 1927. The new product may especially be produced as a slag by reducing oxides or oxide ores in electric furnaces. A typical slag of the new kind has for example the following composition:

Per cent Silicic acid 11.2 Aluminum oxide 34.5

' Iron oxide 3.0 1 Titanium oxide 2.0 Manganese oxide 0.4 Chromium oxide 21.5 Calcium oxide 3.2 Magnesium oxide 23.6

The relation between the contents in the n slag of magnesium oxide. and aluminum oxide respectively may be varied within very wide limits. However, the magnesium oxide cohtentshould be at least 15% and the aluminum oxide content preferably greater than If no chromium oxide is occurring, the total content-of oxides of magnesium and aluminum together with in certain cases occurring titanium should-at least amount to 75% of the total oxide content of the slag. The content of silica should be low or less than 15% and suitably; below 12%. The content" of iron oxides in the slag should be less than 5%. A considerable amount of chromium oxide has proved to have a very favorable influence upon the chemical resistance of the refractory slag. Said influenceis considerable already by 5 to 8% Cr O The best" results, however, are obtained with a chromium oxide content from. about 10 up to about percent. In case of chromium oxide the content of chromium oxide in'excess of 5% counted together with oxides of magnesium and aluminum should preferably amount to at least 75% of the total oxide content of the slag.

p The new product may be obtained in electrio furnace reduction processes either by selection of the raw materials for that purpose or by adding slag forming admixtures in form of material containing magnesium oxide, aluminum oxide or chromium oxide.

The reduction may for instance be utilized in the production of iron or ironalloys out of iron ores. I Such-ores contain usually comparatively small quantities of magnesium oxide and aluminum oxide but on the other hand often a considerable content of silicic acid. Most convenient for carrying out the process is to select ores with low or a comparatively low silicic .acid content because in such cases. it will be easier to adapt the composition of the slag so that a good highly refractory material can be obtained out of it. If however, it is not possible bysuitably selecting the raw material to obtain a slag with low silicic acid content special slag forming admixtures are to be used. As v slag forming admixtures in the process, magnesite in a burnt or unburnt state and bauxite are used with advantage. ore contains a high'percentage of silicic acid, the same may, however, be decreased to a percentage low enough forobtaining a highly refractory material. This may be done either by reducing a part of the silicic acid so that iron containing silicium is obtained, or by adding magnesite or, bauxite with a lowcontent of silicic acid, or by adding a larger quantity of such material that might.

contain a somewhat higher percentage of silicic acid but still substantially less than 15% of the slag forming oxides in the said admixtures. It is of advantage to regulate the process in such a way that the silicic acid content in the slag is less than 12%, while hereby besides a more refractory material, a substantially increased resistance against chemical influences is achieved. For the rest the proportions between iron ore and slag forming ingredients containing MgO or A1 0, may be varied within very wide limits. Even iron ores'containing titanium may be used in the process. The reduction process is then suitably so carried out: that all or a part of the titanic acid in {the ore goes into the slag as a component.

If the iron into suitable moulds, whether the same has the first with the such as place be produced in connection production .of chromium alloys,

may for example be obtained by so adapting the composition of the charging materials in reduction chromium, chromium steelor other chromium alloys, for example by adding magnesite Nor bauxite or both, that a desired chromium content is received in the slag- It is especially suitable tg decrease the total content of silicic acid; and ferrous oxide to at the most The content of magnesium 'oxide in the slag may partly be replaced,-but atthe most to oneifourth, with calcium'oxi-de. "The highly refractory materials may of course also be produced by smelting together materials suitable for the purpose. 'One may then start either from the simple oxides themselves or from suitable minerals and out of them for example produce a refractory material holding in accordance with the above statements for the main part oxides magnesium and aluminum,-

-- of chromium,

chromium oxide for exampleoccurring in quantities from a few up to and magnesium oxide from 15% and more. 30' The smelting maybe undertaken in tapf ping furnaces. as well as, for example 1n batch processes, in furnaces of the same kind as ordinarily used in the production of alundum. The received smelt may'be directly cast been obtained inthe for of a slag from any metallurgical or othe reduction process or if the same has been, brought into molten condition by means 'of'other smelting ro-' low carbon ferrorchromium. y 5 highly refractory product containing C130 processes for producing ferro- 5% of oxide of chromium, not less than 75% of oxides of magnesium, aluminum and chromium counted together, and with a content of silica less than 12% and of oxide of iron less than5%, characterized by high softening temperature and resistance against chemical erosion. 2. As a new article of manufacture a .fused refractory material containing not less vthan 5% of oxide of chromium, not less than F 15% of oxide of magnesium, not less than 75% of oxide of magnesium, aluminum and chromium together, and from 5 up to 12% of silica.

- v3. A refractory material having as an essential component particles of a fused re-,

fractor 35% o oxide of chromium, not ,less than 15% of magnesium oxide, not less than 75% of oxides of magneslum, aluminum and chromium; counted together, less of silica, less than 5% of iron oxides, and calcium oxide in an amount less than" one fourth of the percentageof magnesium oxide. V 4. A- refractory material having as an esmaterial containing from 5 up to than 12% 25% of oxide of alum1num,'not'lessthan sential component'particles of a fused refractory material containing not less than 5% of oxide of chromium, not less than 75%- of oxides of magnesium, aluminum and,

my hand.

j ROBERT 'HAGLUN D.

' cesses. For this. purpose it is ofadvan age that the total content of oxides of iron nd silici-um be not -too low.

' 45 Hereby a more fluid slag stone are obtained.

The same Should 1 .-:in such a case not be less than about.5%.-"

and a tight-slag 1 Another way of treating the new refracv tory material consists in crushing the cooled mass or for smelt and using it as avstampl- 60 the manufacture of bricks. As inding a cut small quantities of claysubstances, sodlum silicate, Sorel cement, suitable hydrates, such as those" of magnesium,

I m1um, or-other binding 55 means may be used.

The new highly refractory. material or the articles an" 'extraor (produced thereof possess besides inary. high refractoryability] aluminum or chroand a 'hig h softening temperature a-great chemical 'resistanceq- It is for instance esuse in open hearth fur-' channels and 60 pecially'suitable for naces, arches, liningof furnace as material for furnace bottoms.

Y Iclaim:-

1. As a new article of manufacture afused I 65 refractory material containing not less than of silica and less than 5% of iron ox,-

In testimony whereof have hereunto set