01. Specific measures for converter optimization
1. Optimization of converter type
The permanent layer of the bottom of the 210t converter in the steel plant is designed to be 195mm, the thickness of the magnesia carbon bricks in the bottom working layer is 800mm, the furnace volume ratio is 0.86m³/t, and the working layer is a smooth transition from the center brick to the molten pool. The center brick of the bottom is at the lowest position. Design of converter bottom before optimization As the demand of steel enterprises for the purity of molten steel increases, the bottom blowing flow of the converter has gradually increased in recent years. The operating pressure of the converter bottom is large, and the arc masonry starts from the center of the bottom. The surrounding slope is large, which causes the bottom of the converter to erode from the center brick during operation and gradually spread to the 10th ring of the bottom. The residual thickness of the converter 3500 is 600~700mm (including the permanent layer), and the erosion rate is about 0.11mm/furnace, which leads to high maintenance consumption during the operation of the converter and affects the operation efficiency of the converter. The design of the working layer of the furnace bottom can no longer meet the smelting needs of the steel plant. Therefore, the furnace type is optimized and modified. After optimization, the design of the converter furnace bottom is optimized and adjusted, and the working layer of the furnace bottom ring 1~13 is thickened to 1000mm. And the shape of the furnace bottom ring 1~6 is designed as a "flat pan" type. The working layer bricks are closely attached to the permanent layer and are laid in a circular manner to the 6th ring of the furnace bottom. The arc transition starts slowly from the 7th ring. After the optimization, the center brick is no longer the lowest point. The center brick of the furnace bottom to the sixth ring is flat, which jointly bears the stirring and static pressure of the molten steel.
2. Optimization of converter refractory matching
During the use of different converters, due to the influence of many factors such as different molten iron composition, smelting process, different steel grades and auxiliary equipment, some local areas of the converter erode too fast. In order to reduce the erosion rate of the converter during operation and avoid the serious lack of residual thickness when the converter is offline as much as possible, the overall or local grades and materials are optimized during the converter material design process.
The thickness of the decarburization layer of ordinary magnesia carbon bricks is 2.4 times that of low-carbon magnesite carbon bricks. At the same time, compared with high-carbon materials, the spacing between MgO particles in magnesium carbon bricks with low carbon content is small, and it is easy to form a MgO-rich reaction layer on the working surface of the material. After oxidation, the magnesia-c bricks are more compact and have better oxidation resistance.
3. Control of converter final slag
The use of high-quality converter refractory magnesia carbon bricks is the basis for the safe and smooth operation of the converter, and is also closely related to appropriate converter operation and on-site maintenance. The content of Si, Mn, and P in molten iron with different components, the position of the converter smelting gun, especially the slag splashing operation and proportion, the end composition and the final slag control, will have a certain impact on the erosion of the converter lining. The main substances that affect the melting point of the converter slag are FeO, MgO and basicity. At present, the TFe of a certain steel plant is generally 15% to 20%. At a certain TFe ratio of the converter final slag, the higher the basicity and Mg0% content, the higher the melting point of the slag and the more viscous the slag. From the perspective of furnace protection, the more favorable it is to the furnace lining, the steel mill generally controls the converter basicity at 2.8~3.2 for cost considerations. The basicity and MgO content of the final slag of a 210t converter before and after optimization, the basicity of the final slag increased from 2.9 to 3.3 before and after optimization, and the MgO content of the final slag increased from 5.8% to 6.5%.
