1. Construct the furnace either by one kind of brick or by two kinds of brick, the required matching percentage of brick in theory may differ from the actual percentage affected by distortion of cylinder. So there is no need to use bricks totally as the theoretical required amount while constructing the furnace. It’s a key point to lay the big side of brick close to the cylinder when doing the construction, and the bricks should be laid straightly and there had better no gaps between each two bricks. Fill the gaps and distortion with mortar, the repair seam line should not be too hard in case of breaking of bricks.
2. Abandon the twisted bricks which are out of distortion standard, making sure that the bricks are tightly bonded and no looseness. While construct the furnace by bricklaying machine, the upper brick especially alkaline brick can not be given too much pressure, because alkaline brick’s strength at normal temperature is relatively lower. Avoid bricks broken by uneven compression, so that to avoid kiln body falling off while working.
3. While laying alkaline bricks, watering or grouting the brick upper surface is prohibited. The well up cement mortar should be cleaned before it hardens.
4. Construct the furnace strictly according to each brick matching method to avoid distortion of brick block and kiln body working out of balance, furthermore to avoid affecting working cycle.
5. During the construction, check carefully and immediately both annular flatness and axial flatness according to the datum line in every circle and section. Parallel vertical seam line with furnace axis, parallel annular seam lines with each other, and make the parallel annular seam line vertical with the furnace axis. If the furnace body distorts or the bricks are irregular, adjust the body by steel plate and the bricks by cement mortar. The steel plates should just fit with the bricks (the length and height of steel plate should be 5mm smaller than those of brick).
6. When finish semicircle construction of the furnace, firstly check the deviation of vertical seam line with datum line and annular seam line with datum line, then lay one tier or two tiers of bricks, set up the mandrel and turn the furnace by 900. Construct the left half furnace on the other side, set up another mandrel while finishing one section. Turn the furnace after the mortar hardens.
The MgO in slag is eroded usually by furnace lining while making steel. In the process of smelting, the slag and refractory materials will get touched; MgO concentration in slag should almost reach saturation. There is a close relationship between the content of saturated MgO and CaO/SiO2. For slag with low alkalinity (CaO/SiO2<2.0), the higher the proportion of FeO is, the lower proportion of saturated MgO. When FeO content is low and saturated MgO content is high, the slag will erode more refractories. While for slag with high alkalinity (CaO/SiO2 >2.0), the saturated MgO content will not be seriously affected by the FeO content, what’s more the slag will not erode much more refractories. Therefore, improve slag alkalinity can strongly protect refractories.
The service life of ladle is directly influenced by refining time, so it is important to improve steelmaking technology so that to shorten smelting time.
The service life of ladle will be reduced by 3 -5 heats once shut down, so to achieve efficient production, the key is shortening smelting cycle. On the premise of using advanced technology to guarantee the best steel quality and the lowest total consumption, shorten the smelting cycle to the minimum, improve equipment and shorten shut down time.
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