The service life of the converter lining was affected by these factors, so don't make a mistake!

There are 2 sets of 60t converters, and the masonry structure of the converter is: 520mm of eye-shaped bricks, 9-layer 520mm and 14-layer 460mm transition zone above the wind eye, 380mn below the eye-eye zone, and refractory materials are built around the furnace mouth. The wind eye area and above are thicker in the building, in order to enhance the erosion resistance.

Production practice shows that the vulnerable parts of the converter lining are: furnace mouth, wind eye, end wall . During the blowing process, it is subject to severe mechanical scouring of high temperature melt, severe erosion of slag and quartz flux, periodic fluctuation of furnace temperature, mechanical collision and wear during furnace cleaning and eye eye maintenance, and extremely harsh operating conditions, especially furnaces. The mouth, the wind eye and the end wall slag line are not only the vulnerable parts of the refractory material, but also the weakest link of the masonry structure, or the part with the highest technical content in the road construction. The synchronous life of these three parts largely represents the age of the converter.

According to the production practice, when the thickness of the brick in the wind eye area of ​​the converter is less than 90mm, it can no longer be used. It is necessary to stop the furnace to dig up. When the rest of the masonry is below 150mm, it needs to be overhauled.

There are many reasons for the damage of the converter lining. In summary, it is mainly the result of three kinds of effects: mechanical force, thermal stress and chemical corrosion .

2.1 The influence of mechanical force

2.1.1 Abrasion of the energy of the melt to destroy the brick lining

Due to the impact force of the blasting gas and the rise and expansion of the gas stream, a large agitation energy is supplied to the melt. When the gas-liquid two-phase mixed fluid impacts the surface of the melt, the melt is sprayed onto the brick lining by the gas-liquid two-phase fluid. It creates a strong mechanical impact on the furnace lining and also creates conditions for chemical erosion. Therefore, choosing a reasonable blast intensity is an important part of improving the life of the converter furnace. The relatively suitable supply air intensity and air supply system are beneficial to weaken the melt lining. The impact force extends the life of the converter.

2.1.2 Clean up the damage of the eye to the eye brick

In the process of blowing, magnetic iron is inevitably formed. When the hurricane eye is operated, the melt is recirculated in the tuyere region, and the nodule is easily formed in the tuyere. The tuyere needs to be cleaned continuously, and the mechanical shock force destroys the brick lining in the tuyere region. It is very large, causing the surface of the brick lining in the tuyere area to deteriorate under the action of melt erosion. When the metamorphic layer is expanded to a certain extent, the brick body peels off, which seriously affects the furnace life.

2.2 Influence of thermal stress

The resistance of refractory materials to damage caused by temperature changes during heating and cooling is called thermal shock resistance, which is an important indicator for measuring the quality of refractories. Most refractory materials are damaged by thermal shock resistance at temperatures far below their refractoriness. The thermal damage of refractory materials is mainly related to the thermal stress generated by refractory materials during production.

The converter is a cyclical operation, and it is inevitable that the fluctuation of the converter furnace temperature will occur due to the failure of the material, the furnace mouth and the equipment failure.

2.3 The impact of chemical erosion

Chemical corrosion mainly includes melt erosion (slag, metal solution) and gas erosion. It is characterized by dissolution, compounding and infiltration of magnesia refractories, which causes structural changes in refractories and weakened performance.

2.3.1 Melt erosion

The melt contacts and penetrates through the pores, cracks and interfacial interfaces of the refractory material. During the contact process, the refractory material dissolves into the melt, and the surface of the refractory material forms a soluble compound having a large change in bulk density and raw material. When dissolved to a certain extent, osmosis occurs, and when the melt penetrates into the refractory material to a certain depth, it will be produced and The metamorphic layer of completely different materials has a volume change due to the different structure of the metamorphic layer and the structure of the raw material, resulting in structural stress, which leads to cracks in the production of raw materials. Severe cracks cause the metamorphic layer to peel off or crack, and new ones are generated under the erosion of the melt. The metamorphic layer, which circulates, causes severe damage to the refractory material.

2.3.2 Gas erosion

Gas erosion generally means that SO2 and O2 in matte react with alkaline oxides in refractory materials during the blowing process to form metal sulfates, which are smaller in density than alkaline oxides due to the volume of the two phases. The density is different to cause stress, which makes the refractory material loose and peel off, which exacerbates the damage of the refractory material.

3.1. Change the masonry method and improve the process standard

3.1.1 Under normal circumstances, due to wet construction, the brick body will be damp, which is not conducive to constant temperature dehydration at 400 °C. The converter masonry adopts dry and wet combination, that is, the upper and lower layers of the tuyere area and the furnace mouth area are wet-laid, and the rest are dry.

3.1.2 The tuyere bricks are changed from one end masonry to the middle to the two ends to avoid triangular seams and misalignment of the tuyere bricks.

3.1.3 From the one end of the upper and lower furnace mouth to the opposite arch bricks from the center to the two ends, and symmetrically carried out, which facilitates the closing and locking of the two sides to prevent the two bricks from being uneven and not tight.

3.1.4 The distribution inside the brick joint is full, uniform, uniform inside and outside, the expansion joint meets 2-3mm, the joint of each part of the brick body is locked, the processed brick body is not more than one third, and the processed brick body is not less than Two-thirds of it.

3.1.5 Magnesium fillers are required to be kneaded into a mass, which is scattered from a height of one meter, and the filler is uniform in thickness and uniform in firmness.

3.1.6 Broken, broken angle and damp chrome-magnesia bricks are resolutely not used.

3.2. Control the cold material of the converter to prevent high temperature corrosion

Tests have shown that when the chrome-magnesia brick is resistant to thermal shock at 850 ° C, breakage will occur 18 times, resulting in damage to the furnace lining. Therefore, it is necessary to avoid the fluctuation of the furnace temperature and the violent fluctuation, and reduce and eliminate the damage of the thermal stress on the brick lining. In the production, the method of controlling the amount of cold material added is used to stabilize the furnace temperature.

3.3. Reasonably control the silicon content of the converter slag to reduce chemical corrosion

Neutral or weakly alkaline slag protects the furnace lining. The peridot has a serious erosion of the magnesia, which not only dissolves the surface of the magnesia refractory, but also penetrates into the interior to dissolve it.

The higher the temperature, the greater the solubility of MgO in the converter slag, and the formation of forsterite with lower load softening temperature at high temperature, reducing the working performance of the magnesia brick. Iron oxides can also saturate the periclase and chromite grains, causing grain damage and causing excessive damage to the magnesia bricks. The silicon content of the converter slag is less than 18%, which is alkaline. The silicon content of the converter slag is more than 28%, which is acidic. Both of them severely corrode the magnesium oxide brick lining. The converter slag contains between 19% and 24% silicon, which is neutral or weakly alkaline and does not corrode magnesium oxide brick lining. In production, the silicon content of the converter slag is strictly controlled to stabilize between 19% and 24%.

3.4, improve the quality of operators

Improve the quality and capacity of furnaces, converters, and production managers to ensure the quality of the furnace.

Improve the ability to respond to emergencies, and scientifically and closely monitor and manage production.

3.5. Reasonable choice of wind supply intensity and oxygen enrichment concentration

In the production process, it is inevitable that the furnace body and the fan do not match. It is strictly forbidden to supply the small furnace body with a large fan to prevent the blasting of the tuyere and the severe melt. The oxygen enrichment concentration of the converter should not be higher than 27%, the oxygen enrichment concentration is greater than 27%, and the brick lining is washed more.

Attention should also be paid to the following aspects in production:

(l) Establish scientific standards for shutdown, repair and opening, such as brick lining removal standards, heating standards, etc., and strictly enforce them.

(2) The newly repaired furnace body shall be operated with “hanging furnace” and “permeating copper” to protect the furnace body.

(3) Strict process operation, the control of the furnace temperature and the judgment of the end point in each stage should be accurate. Eliminate the occurrence of "over-blowing" phenomenon, especially the two-cycle over-blowing, which is very serious damage to the furnace body.

(4) Pay attention to the training of employees and improve the quality of all staff and the technical level of copper smelting.

Through the implementation of the above measures, the energy consumption per ton of copper bricks is well controlled, reducing costs and creating annual benefits. As long as the masonry quality is emphasized, the process conditions are emphasized, and the thermal stress, mechanical force and chemical corrosion of the chrome-magnesia bricks are eliminated, the life of the furnace bricks can be prolonged.

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