DE1191343B - Process for the production of carbides, borides and silicides of III. and IV. Main group of the periodic system, the vapor phase of which in the arc conducts the electric current poorly - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

BOIk

German class: 12h-4

Number: 1191 343

File number: E 17819 IV a / 12 h

Filing date: June 24, 1959

Opening day: April 22, 1965

During a process in an electric arc furnace, a very good conductive floor material is created and not none Slag, the current is transferred through the vapor layer of the soil material in the arc. If the soil body is a material whose vapor layers in the arc the electrical Conducts electricity poorly, so it is necessary to bring the electrode almost up to the bath in order to To get continuity. In practical operation, however, the bottom layer can be touched can hardly be avoided, especially because during reduction processes the bath is caused by the evolution of gas wells up. The contact with the bath, which is to be equated with a short circuit, increases temporarily the current consumption to impermissibly high values, which makes it necessary to remove the electrode withdraw from the bathroom. However, this has the consequence that the furnace with an economically interesting Load cannot be operated.

A process has now been found for the production of carbides, borides and silicides III. and IV. Main group of the periodic system, whose vapor phase in the arc corresponds to the electric Conducts electricity poorly, with a starting material present in shaped bodies, which is in finer Distribution with the largest possible surface area of carbon and a corresponding to the desired end product, Contains oxygen-containing material, is converted in the arc. The procedure is through characterized in that one of the starting materials, which the electric current in the vapor phase poor conductors, alkali and / or alkaline earth compounds, preferably about 0.1% of the Möllers and less, clogs.

It is possible to use the alkalis and / or alkaline earths or their connections in whole or in part by rare earths and / or their connections to replace.

It is known that raw materials such as coke, charcoal, clay or quartz sand naturally do so contain a lot of alkali or alkaline earth compounds that the Möller contains about 0.1%. With the invention However, the process requires an additional amount of alkali or alkaline earth compounds sufficient, which causes undisturbed work. By dosing the additive can also Temperature influenced and the formation of a desired type of compound are preferred.

The usual starting materials are used as raw materials for the individual element or for the compound. It is advantageous to use lumpy, granular material or moldings in such a mixture.
Borides and silicides of the III. and IV. Main group of the periodic system, the vapor phase of which in the arc generates the electric current
poorly conducts

Applicant:

Elektroschmelzwerk Kempten G. m. B. H.,

Munich 22, Bruderstr. 12th

Named as inventor:

Dr. Adolf Vogt, Munich;

Dr. Günter Wiebke,

Schelldorf (Allgäu), Post Kottern-Neudorf

to use that the furnace gases formed can escape unhindered.

When carrying out the process, the raw materials and the additive can only be processed as a mixture will. Raw materials that are in fine form are expedient with the reducing agent and the additive mixed, optionally moistened, if necessary using a Binder, e.g. B. deformed dextrin, possibly dried and crushed to a usable Möller, unless the dried material is directly suitable for processing. The processing takes place in each case in as little water as possible. The material prepared in this way can also be processed with a mixture consisting of additives and raw materials or with a Möller without addition.

The additives can be added to the raw materials before shaping.

If the raw materials are used in a mixture, the additive is expediently added to the Möller.

example 1

In an electric arc furnace 60 cm long, 50 cm wide with a carbon bottom and two vertically from above Boron carbide was melted into the adjustable graphite electrodes with a diameter of 100 mm. For this purpose, a Möller was produced in such a way that 75 kg of boric acid and 25 kg of finely ground petroleum coke with 88% carbon with 601 water, the 60 g caustic

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soda were added, were made into a paste. The wet mixture was placed in shallow cups and dried in the usual way in a steam drying cabinet with air circulation. The den Flat cakes removed from cups were mostly crushed into 4 to 8 cm pieces and with these the furnace is loaded.

At 80 volts and 2000 amperes, the furnace ran smoothly and evenly with completely covered electrodes, with the resulting furnace gas burning off on the charging surface without blowing. The molten soil material corresponding to the formula B ₄ C formed a uniform, completely melted bath under the electrodes, which completely converged between the two electrodes.

When working on a technical scale, pieces up to 30 cm in size were made by the same Möller continuously melted and the bath tapped at intervals of 2 to 4 hours.

Example 2

The oven described in Example 1 was made with a Möller made of powdered boric acid and ground Petroleum coke charged, with the components in the same ratio as in Example 1, but without Added caustic soda were mixed. The stove ran very unevenly and the power consumption could not cannot be increased beyond about 1200 amps. When the electrodes were lowered further, a short circuit occurred with the soil body, which forced business interruptions. Despite what is possible in this way After only 20 minutes, the mixture caked with only a slight load, so that the furnace gases could no longer escape evenly. Individual holes formed in the sticky mixture through which the furnace gases escaped stormily. In contrast to the lumpy Möller in Example 1, which progressed evenly by itself to the extent of the chemical conversion, In the present case, it was not possible for the powdery mixture to fall back because it was violent blowing furnace gases continued the powdery Möller.

Example 3

In the same furnace and in the same manner as in Example 1, boron aluminum was produced by Melting down a Möllers at 80VoIt voltage, which consists of a mixture of 90 kg boric acid, 4.8 kg of clay, 32 kg of petroleum coke and 0.5 kg of caustic soda were obtained in lump form as above became. By increasing the addition of caustic soda, the temperature in the furnace was lowered and thereby caused the formation of an aluminum boride with a higher aluminum content

Example 4

In the same furnace as in Example 1, the following mixture was melted, which in the same In the same way as in example 1 it was prepared with water and processed into pieces:

100 parts by weight boric acid,
18 parts by weight of sand,
44 parts by weight of carbon black,
0.5 part by weight of caustic soda.

At 80 volts and 2500 amps, the oven was very quiet. A completely melted one was obtained Block of composition 23.5% C, 28.5% Si, 47.8% B.

Example 5

In the same furnace as in Example 1, the following mixture was melted, which in in the same way as in example 1 was prepared with water and processed into pieces:

75 parts by weight boric acid,
32 parts by weight of sand,
37 parts by weight of carbon black,

36 parts by weight of borax, containing water of crystallization.

As in Example 4, the furnace operation was very quiet at 80 volts and around 2500 amps. A borosilicon of the approximate formula SiB ₃ with a low carbon content was melted.

Claims (1)

Claim: Process for the production of carbides, borides and silicides of III. and IV. main group of the periodic system, the vapor phase of which in the electric arc conducts the electric current poorly, with one in shaped bodies present starting material, the finely divided carbon with the largest possible surface and contains an oxygen-containing material corresponding to the desired end product, is implemented in the arc, characterized in that the starting materials, which conduct the electric current poorly in the vapor phase, alkali and / or Alkaline earth compounds, preferably about 0.1% of the Möllers and less, added. Considered publications:
German patent specifications No. 382 684, 431759, 578375, 716760, 903271, 956 579; German Auslegeschriften No. 1020 318, 1045 988; U.S. Patents Nos. 2285 837, 2756126, 2883268. 509 540/328 4.65 © Bundesdruckerei Berlin