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The ferroalloy factory encountered problems with electric furnaces in the production

The ferroalloy factory encountered problems with electric furnaces in the production

The Ferro alloy manufacturer encountered problems with electric furnaces in the production.

Ferro alloy manufacturer

The working environment of a submerged arc furnace

Ferro alloy manufacturer Submerged arc furnace alloy smelting is a multiphase physical and chemical process carried out at high temperatures, and the working conditions of refractory materials in the furnace are very harsh. The temperature in the reaction crucible area of slag-free smelting can reach 2000~3000°C, while various erosions also occur in the high-temperature area of slag-containing smelting.

Ferro alloy manufacturer Damage Mechanism of Submerged Arc Furnace Refractories

  1.  Corrosion phenomenon: Corrosion occurs when the working temperature of the refractory material exceeds its refractoriness. Corrosion often occurs in the furnace wall near the arc zone, the bottom of the electrode end and other parts. Through the analysis of the furnace ground temperature measurement patch and thermocouple data, the bottom temperature of the electrode end of the furnace bottom is the highest. At the same time, if the working end of the electrode is too long, the temperature of the furnace bottom will rise significantly.
  2.   Chemical attack: Various chemical reactions between refractory materials and slag, molten metal, dust, waste gas and other substances are called chemical attack. The types of chemical attack are gas-solid reaction, liquid-solid reaction, liquid-liquid reaction and gas-liquid reaction. When the working temperature of the refractory material is close to or exceeds its refractoriness, the chemical corrosion of the metal to the refractory material is more prominent.
  3. Mechanical action: In the working layer, the refractory material whose temperature is higher than the softening temperature under load is extremely vulnerable to loss due to the mechanical action of metal and slag.
  4. Spalling and cracking: Under rapid cooling and rapid heating or uneven thermal load, the internal thermal stress of the refractory material exceeds its structural strength and local damage occurs. After a long time of shutting down and starting the furnace, the expansion and cracking of the furnace body are particularly obvious, and this kind of scene can also be observed in the taphole chute.

Ferro alloy manufacturer Selection of refractories for submerged arc furnace body

The lining of a submerged arc furnace is composed of a heat insulation layer, heat insulation layer, heat preservation layer, and working layer. The smelting process is in a complex environment of high temperature, corrosion, and heat loss. The damage to the furnace lining increases energy consumption and production costs. An important direction for the energy saving of the furnace.

  • For the lining life of a cast iron electric furnace, forced water cooling can be used to hang the slag lining. 

The process is to build the furnace with low thermal resistance refractory materials and equip it with cooling facilities. By cooling the furnace shell, the molten iron or slag on the inner surface of the furnace lining forms a layer of solidification. The solidified layer separates the furnace lining from the slag iron to protect the furnace lining.

  • Submerged arc furnaces for smelting ferrosilicon and silicomanganese are mainly built with carbon bricks.

 Carbon bricks have the advantages of high melting point, good thermal shock resistance, high-temperature strength, and not easily infiltrated by alloys and slag.

  • High-carbon ferrochrome is mainly built with magnesia bricks.

 Magnesia bricks have high strength and high-temperature resistance and are mainly used in alkaline slag smelting. The load softening temperature of magnesia bricks is 1550°C.

  • The refractory materials used in the nickel-iron submerged arc furnace include carbon bricks, chrome-magnesia bricks, and magnesia ramming materials. 

Carbon bricks are used to build the furnace wall and furnace bottom. Since the electrode paste is used in the carbon brick building process, under the action of high temperature, the electrode paste produces volatiles, which cause micro-slits between the carbon bricks, and the liquid nickel-iron will penetrate into the carbon from the micro-slits. The bottom of the brick makes the carbon brick float up. The use of magnesia-carbon bricks or carbon bricks to build the furnace bottom also has the phenomenon of magnesia-carbon bricks floating up. Magnesia ramming materials are generally used for furnace bottom masonry.

 

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