What are the reasons for damage of refractory products in various parts of the converter working lining?

September 10, 2018

What are the reasons for damage of refractory products in various parts of the converter working lining?

The damage mechanism of the converter lining is very complicated. In general, under the combined action of physical, chemical and thermal stress, the oxygen converter lining has mechanical wear, erosion, erosion and hot peeling, which eventually leads to the damage of the lining. Because the working conditions of each part of the converter lining are very different, the damage is different, too. Therefore, the performance of the refractory products for each part of the working lining of the converter is very important.

Furnace mouth and cap parts: mainly by high-temperature gas scouring, furnace spray, often adhered to slag and metal. When the attachment is cleaned, it is subjected to mechanical impact, and the two furnace steels during the smelting period by strong thermal shock. Therefore, the refractory products required for masonry have high thermal shock resistance and slag resistance, slag resistance and high temperature furnace gas scouring, and are not easy to stick steel, even if the steel is also easy to clean. In short refractory bricks -magnesia carbon bricks with high temperature and strength are often used in this part.

Furnace lining charging side: in addition to being corroded by molten steel and slag, it is also subjected to strong impact of scrap steel and strong scouring of molten iron during charging, and this effect is very serious. Therefore, the refractory product required for masonry on the converter charging side has high temperature and strength, good thermal shock resistance, and high slag resistance. So most of the areas used are magnesia carbon bricks with high corrosion resistance and high thermal shock resistance.

Furnace lining tapping side:less affected by thermal shock, but by the hot flushing action of the molten steel. This part can be used with the same level of refractory products as the charging side , and the thickness might be slightly thinner.

The trunnion parts on both sides: in addition to the erosion of molten steel and slag during the blowing process, but also by the erosion and oxidation of the airflow, the surface is covered with no slag layer, so the carbon in the lining brick is easily oxidized, and further damaged it is not very good to repair, so the erosion is serious. When building, it should be made of magnesia carbon brick with high oxidation resistance and slightly higher carbon content.

Slag line part: It is a serious part that is eroded by slag when contact with slag for a long time. The slag line on the tapping side changes with the tapping time, and the damage is not obvious enough; but the slag side is more severe due to the strong slag erosive effect and other effects suffered by the belly of the converter during the blowing process. Therefore, high-corrosion-resistant magnesia carbon bricks should be used.

The molten pool part: although it is affected by the erosion of molten steel in the blowing process, the damage is lighter than other parts, and the operation of the slag splashing protection of the converter tends to increase the bottom of the converter, so the molten pool part of the converter can use ordinary magnesia carbon bricks.

The steel tapping hole: the tapping port is affected by the erosion and erosion of high-temperature molten steel and slag, as well as the sharp change of temperature, and the damage is more serious. Therefore, masonry bricks with good erosion resistance and high oxidation resistance should be built. Use integral magnesia carbon bricks, or combination of magnesia carbon bricks, and repair or replace them after a certain number of uses.

Physical and chemical indexes of refractory for different parts of converter:

Brand

MT-14B

MT-14A

MT-18A

MT-10A

GQ-1

GQ-2

Material

Magnesia carbon brick

Magnesia carbon brick

Magnesia carbon brick

Magnesia carbon brick

Magnesia carbon brick

Magnesia carbon brick

Application part

Furnace bottom /Furnace cap

Furnace cap/Steel tapping hole

Furnace body/Ear axis/Molten pool

Steel tapping hole

Gas supply brick

Gas supply brick

w(MgO)/%

≥74

≥76

≥72

≥80

≥70

≥85

w(C)/%

≥14

≥14

≥18

≥10

≥15

≥6

Apparent porosity/%

≤3

≤3

≤3

≤4

≤5

≤5

Bulk density/g·cm-3

≥2.95

≥2.95

≥2.92

≥3.00

≥2.85

≥2.95

Crushing strength/MPa

≥35

≥40

≥40

≥40

≥35

≥40


 

 

 

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