CS273874B1 - Mixture for electroinsulant production on periclase base - Google Patents

Abstract

The mixture for production of electro-insulating material based on periclase that contains from 60 to 95 percent by weight of magnesium oxide, from 1 to 14 percent by weight of silicon oxide, up to 10 percent by weight of aluminium hydroxide and up to 4 and 18 percent by weight of acetic acid. The magnesium oxide can be in the form of equivalent quantity of magnesite or hydromagnesite.

Description

BACKGROUND OF THE INVENTION The present invention relates to a composition for the manufacture of a periclase-based electrical insulator. The production belongs to the sphere of preparation of pure chemicals with subsequent use in the electrical industry.

Periclase as electrical insulating material has been industrially produced by melting magnesite (MgCO 3) or magnesium oxide (MgO) or hydromagnesite (Mg 3 / OH (CO ₃ ) _{2 /} 2.4.4) in an electric arc at 3200 ° C for 15 to 80 hours . The product is ground and used as an electrical insulator primarily in heating elements. Attempts have been made to obtain periclase with electroinsulating properties by annealing said raw materials to temperatures of 1000 ° C to 2500 ° C using chlorine, fluorine or directly from magnesium chloride or the addition of organic acids. The disadvantage of the first method of production - electrical construction - is the high energy intensity. The second way - using different chemicals - either does not give periclase with all electrical insulation parameters, or is ecologically disadvantageous for toxic drift.

Therefore, it seemed useful to monitor the production possibilities of periclase while reducing energy consumption while avoiding environmentally harmful debris. This goal was achieved by the addition of silica, acetic acid (CH-jCOOH) or with them aluminum hydroxide (Al / OH / p). Silicon dioxide and possibly aluminum hydroxide enter the structure of periclase, acetic acid promotes its crystallization and at elevated temperature The addition of these additives leads to a decrease in the crystallization temperature of the periclase with a stabilized structure, so that the temperature of formation of the electrical insulator could be reduced to 1,450 ° C to 1,900 ° C with a holding time of 1 to 3 hours. material for use in heating elements, high electrical resistance, low leakage currents, necessary service life at the required output of the heating elements and loose properties necessary when filling the heating rods. burning at 1,450 ° C to 1,650 C in ^D held for 1 to 3 hours, the periclase produced in this way can be used in a mixture with previously imported and manufactured electrical buildings in a ratio of 1: 9 to 1: 1. When fired at 1,650 ° C to 1,900 ° C usable separately.

The present invention is a mixture consisting of magnesium oxide (MgO) or magnesia (MgCOj) and hydromagnesite (Mg / OH (CO ^) ^ / ^. 4H ₂ 0) doped with silicon or aluminum hydroxide (Al / OH / ^) and acetic acid (CH3COOH). It contains 60 to 95 wt. % magnesium oxide, 1 to 14 wt. % silica, up to 10 wt. % aluminum hydroxide and 4 to 18 wt. of acetic acid. The mixture is stirred with the addition of water as necessary to allow it to be well homogenized. The magnesium oxide may be in the form of an equivalent amount of magnesite or hydromagnesite.

The benefit of the invention for the preparation of periclase-based electrical insulator is in the field of the production of pure chemicals both from the point of view of lower energy consumption of production, from 50 to 70% compared to arc melting, from the viewpoint of ecology conservation and subsequently also in the electrical industry.

The invention is illustrated by the following examples. If magnesite and hydromagnesite are used, their amounts must always be converted to magnesium oxide (MgO).

Example 1

The following mixture was prepared:

MgO 65% wt.

% SiO ₂ 10.5 wt.

% Al hydroxide (OH)?

acetic acid CH-COOH 18 wt.

The mixture was moistened with water, homogenized by stirring and fired at 1550 ° C for 3 hours. The resulting slurry was milled and used as an electrical insulator in a 1: 9 mixture with periclase produced by electric arc welding, and the parameters of this insulator complied with regulations and standards.

4CS 273874 Bl

Example 2

The following mixture was prepared:

MgO 92% wt.

% silica S ^ 4 wt.

% acetic acid CH 3 COOH 4 wt.

The mixture was moistened with water, homogenized by mixing, and fired at 1800 ° C for 1 hour. The resulting slurry was milled and used separately as an electric arc melted periclase. Its parameters complied with regulations and standards.

Example 3

The following mixture was prepared:

MgO 70% wt.

SiO ₂ 10% wt.

aluminum hydroxide Al (OH) 8 wt.

acetic acid CH 3 COOH 12% wt.

The mixture was moistened with water, homogenized by stirring and fired at 1600 ° C for 2 hours. The resulting slurry was milled and used in a mixture with periclase produced by electric arc welding in a ratio of 3: 1 to 1: 1. The parameters of this insulator complied with regulations and standards.

Claims (2)

SUBJECT OF THE INVENTION CLAIMS 1. A composition for the manufacture of a periclase-based electrical insulator comprising 60 to 95% by weight of a composition. % magnesium oxide, 1 to 14 wt. % silica, up to 10 wt. % aluminum hydroxide and 4 to 18 wt. of acetic acid. 2. A composition according to claim 1, wherein the magnesium oxide may be in the form of an equivalent amount of magnesite or hydromagnesite.