DD295334A5 - PROCESS FOR THE PREPARATION OF CALCIUM CARBIDE - Google Patents

Abstract

The invention relates to a method for the production of calcium carbide from calcium oxide and coke in the electric melting furnace. The task of selectively selecting a coke component is achieved by using a coke whose xylitic coke content is less than 10% by mass. {Calcium carbide; Coke; Coke content, xylitic}

Description

Characteristic of the known technical solutions

It is well known to produce calcium carbide from calcium oxide and coke at temperatures above 2 273 K in an electric melting furnace. Here, the content of foreign oxides in the raw materials is of importance. (See, for example, P. HELLMOLD and D. SCHNURPFEIL: Acetylene Chemistry, VEB Deutscher Verlag für Grundstoffindustrie, Leipzig 1986) Based on the o.g. However, it is difficult to see why a thermal pretreatment of the carbon carriers described in DD-PS 158227 in the temperature range from 873 to 1073 K should provide advantages for the process of calcium carbide production. DD-PS 158227 describes how the proportion of volatile constituents of more than 5% is reduced to less than 5% by this pretreatment. As a result, the electrical resistance of the carbon grains decreases significantly.

Furthermore, attention is paid to the structure of the cokes used. It was found that the least ordered carbon material provides the highest carbon turnover (G.PREISSLER: Diploma thesis, Merseburg 1982 and U.SEIBOTH: Diploma thesis, Merseburg 1986). In this work, SEIBOTH conceded that the knowledge presented by him alone is not sufficient to assess the suitability of the coke component used in the technical process, .... as the mechanical and electrical properties of the raw materials used also exert a significant influence. " Our own tests - according to the known state of the art - showed that the reactivity of the respective BHT or coal coke is impaired by a thermal pretreatment .On the other hand, it is plausible that an excessively high content of volatiles in the coke is not only due to electrical reasons Conduct interferes with the technical process of calcium carbide production.

Object of the invention

The invention is based on the goal in the production of calcium carbide to increase the conversion of calcium oxide and coke to calcium carbide or to reduce the material and energy expenditure and to increase the quality of the calcium carbide.

Explanation of the essence of the invention

The invention has for its object to develop a process for the production of calcium carbide in the electric melting furnace at temperatures above 2273 K of calcium oxide and coke, wherein the coke component is subject to a targeted selection.

According to the invention the object is achieved in that a coke is used, the xylitischen Koksanteil is less than 10 parts by mass in%. The lower the xylitic coke content, the cheaper the production of calcium carbide with regard to.

of sales. It was surprisingly found that even contents of xylitol coke of 10 parts by weight in% and below gave sufficiently good results. The advantage of this erfindunysgemäßen approach is that the respective suitable coke for the production of calcium carbide can be selected in advance and a separate thermal treatment of the coke is omitted. Since the content of xylitic components is due to the coal deposit, it is possible to influence the quality of the coke for the process of calcium carbide production at this stage in a targeted manner.

Another advantage of the procedure according to the invention is that in the use of low-grade coke, this can be detected before use of the coke in the process and accordingly the Ofenfahrweise can be adjusted, so that from this perspective safe operation of the furnace results.

embodiments

The invention is explained in more detail below with reference to 2 examples, where the compositions of matter relate to mass fractions in%:

Example 1 (comparative example)

In a laboratory graphite crucible with an inside diameter of 50 mm and a height of 100 mm, 100 g of a mixture of 60 parts of calcium carbide and 40 parts of calcium oxide are added and heated up to temperatures of 1273 K electrically under a nitrogen atmosphere. After reaching the 1273K, an argon atmosphere is used instead of the nitrogen atmosphere and further heated to 2373K.

Upon reaching this temperature, a previously balanced piece of coke is added, the 30 min at this temperature with o. G. Mixture reacts. It is then cooled within 10 minutes. The solidified melt is allowed to stand one day for cooling. The coke is dissolved out of this solidified melt by means of water and dilute hydrochloric acid, filtered off and cleaned of residues of calcium carbide / calcium oxide melt also with water and dilute hydrochloric acid, then dried at temperatures of 453K in a drying oven and weighed. From the ratio of weight to weight, the turnover is calculated in%. The weighed coke had the following composition:

- detrital coke content: 75.1%

- GelitischerKoksanteil: 8.3%

xylitol coke content: 16.2%

- mineral substance: 0,4%

The Kokseinwaage was 5,365g. Of this coke, 12.6% was reacted within 30 minutes. Example 2 (according to the invention) Under the same conditions as in Example 1, a coke of the following composition was:

- Detrital coke content: 84.5%

- gelatinous coke content: 7.0%

xylitol coke content: 8.0%

- mineral substance: 0.5%

used in an amount of 5.216g. 17.6% of this coke was reacted within 30 minutes.

Further experiments with different xylitic coke fractions yielded similar results, with higher turnover

the lower the xylitol coke content was.

Claims (1)

A process for the production of calcium carbide in an electric melting furnace at temperatures above 2 273 K from calcium oxide and coke, characterized in that the coke contains a xylitischen coke content below 10 parts by weight in%. Application of the invention The invention relates to a process for the production of calcium carbide from calcium oxide and coke at temperatures above 2 273 K in the electric melting furnace.