SU65204A1 - A method of manufacturing an electrically insulating material for tubular heating resistances - Google Patents

Description

The present invention relates to a method of manufacturing an electrically insulating material for tubular heating resistors with magnesium oxide insulation, using "alba OR" magnet as the starting material.

In the literature, it is usually noted that magnesia is a material that is practically unsuitable for "preparation for an extender for tubular electric heating elements." in a tubular electric heating element, it should serve as a transmitter of heat from the helix to the upper element and the element.

In order to fulfill this role, the “executor must have good thermal conductivity,” ar d with good electrical insulating ability, dielectric strength and heat resistance.

However, attempts to use machines, in particular in the form of magnesia, as an electrically insulating material are widely known.

As already mentioned above, magnesia alba, carbon dioxide VibVM magnesium (MgCOs), liquefied alba by calcination and mainly magnesium oxide are also used as the starting material. MgO). The magnesia, the alba and the mouth alone, or in a mixture in any proportions, mixes the dough on the water, and makes KOTviporo briquettes of arbitrary size (manually or on a briquetting machine). The briquettes are dried first in air and then in a drying oven.

Due to the property of magnesia sdzhzhivaemosti. After drying, the briquettes retain their shape, are durable and do not crumble.

The starting material is also the use of magnesium alloy with aluminum (electron) in the form of waste — chips and sawdust. After cleaning these wastes from iron and steel impurities that fall in a relatively large amount, they are subjected to burning in the open air with blast, the resulting oxide is mixed with iodine, and briquettes are made of the mixture, which are dried in air and then in a drying cabinet.

The essence of the Invention is the subsequent heat treatment of the said briquettes. According to the invention, the dried briquettes are melted in an arc furnace. With a closed arc to a non-conducting hearth, the inside of the smelted block, Immersed in a pure white color, is separated and subjected to magnetic separation in a fragmented state.

As mentioned above, the smelting of briquettes is made in an arc furnace with a non-conductive hearth, lined with refractory bricks. And then there are also magnesia magnets.

The hearth is laid out with briquettes in order to avoid melting of chamotte bricks with the molten magnesium block magnesia.

The layer of briquettes 200-300 mm is quite sufficient to prevent sintering of the block with the hearth.

In more detail, the process of thermal treating briquettes is as follows.

The arc of the furnace is formed of briquette magnet, and the recess is ignited by the approach of the electrodes, their clamping with a piece of coke or a piece of electrode.

The whole process of silt & vkp is conducted with a closed arc, high currents and low voltage across the arc, with accumulating in the arc-like area, but more heat, which is achieved due to the low thermal conductivity of the briquettes.

In the zone of the arc: As a result of the very high tempera- ture, decomposition of carbon dioxide into magnesium and carbonic acid occurs, which leads to the atmosphere. Then, the melting of the m-apni oxide begins to form a block with a clearly expressed crystalline structure. At the same time, manganese impurities and. they burn out, and if they have an IBI smelted block, then it is removed from the block surface, where the temperature is much lower.

The presence of impurities from the surface of the block is determined by the brown or yellow color of the crystals. The inner part of the block, in contrast to the “underflood”, has a crust.; The structure is pure and it looks like a broken sugar head.

The pure white color of the block is a sign of material acquisition .; which, being crushed and cleaned by magnetic separation from the metal dust. falling with crushed. and grinding, it is a gap for tubular elements .. vol. a: Giving electrical strength, up to 2 К1В / ММ, and e. hectro “zoliruyushcheG: with the ability up to 30-ohm / cm at 1000 ° C.

Tubular electric heaters made with filler obtained by the above method have better qualities than heaters with magnesite filler. The latter always has impurities of CaO, AlsOs, RegOz, SiOp in terms of quantity, not less, passing into the filler during melting. As a result, the quality of magnesite, as a filler, is largely dependent on temperature and decreases sharply with increasing temperature.

In the filler made from magnetism, treated by the method described above, there is no such abrupt change of qualities depending on the temperature of the agent.

Subject invention

1. A method of manufacturing an electrically insulating material for tubular heating resistors by insulating oysi magnesium, using an | M IH as the starting material of magnesia "alba or" mouth, which is kneaded with water, briquetted and dried, differing . that the dried briquettes are subjected to melting in an arc-furnace with a closed arc and non-conducting along the DI, the inner part of the smelted block, having a pure white color, and in a fragmented state is subjected to magnetic separation. 2. Modification of the method according to claim 1, characterized in that an alloy is used as an alloy of the following compounds: In magnesium with aluminum, which is burned, and the square window is mixed with water ii briquettes are made from the mixture.