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What is a GOR converter? How should the lining refractory material be selected?

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GOR converters are mainly used for smelting stainless steel and foundry applications. Now, GOR converters have several converters with nominal capacity of 1.5, 5, 10 and 60 tons in normal production. This process uses converter composite blowing technology to refine stainless steel, and its equipment and smelting process are similar to KiBOP, STP and other processes in Western Europe and Japan. Since the double blowing converter process solves the problem of the life of the tuyere of the AOD furnace, the furnace age is greatly improved. The steel grades produced by the GOR converter steelmaking method are mainly non-ultra-low carbon stainless steels. In the early stage of production, the furnace age was low due to various reasons. After continuous research and transformation, a relatively high furnace age has been achieved, but there are still some problems to be solved.

The GOR converter is a bottom-blown converter that uses multiple energy media for composite blowing. The mixture of nitrogen, oxygen, argon and natural gas with adjustable composition is blown into the molten pool through three sleeve-type nozzles installed at the bottom of the converter. Similar to other converters for producing stainless steel, this process is also divided into three blowing stages for smelting stainless steel: the first stage blows oxygen, and the nozzle is protected by hydrocarbons; the second stage blows oxygen, argon (or nitrogen), hydrocarbons Compounds and their mixed gases; the third stage blows pure argon or nitrogen into the converter bath. The GOR converter adopts bottom blowing, and the design of hydraulic furnace bottom, live furnace bottom and hydraulic furnace cap greatly shortens the masonry and demolition time (16 hours for masonry and 8 hours for demolition). Two sets of furnace bottoms; AOD furnaces usually use bottom side blowing or top and bottom double blowing, and the bottom of the furnace is generally fixed.

(1) From the perspective of fixed investment: the initial equipment investment of the GOR converter is large, the size of the furnace shell is large, and the consumption of refractory materials is large.

(2) From the point of view of smelting cost: AOD furnace has higher requirements on raw materials, usually electric furnace is used to melt stainless steel scrap; GOR converter does not have high requirements on raw material components, saving the consumption of expensive low-carbon and micro-carbon ferrochrome. Due to its strong decarburization ability, high-carbon ferrochromium can be used in large quantities.

In the first stage of blowing, the GOR converter uses hydrocarbon cooling nozzles and does not require argon and nitrogen cooling nozzles. In general, the argon consumption of a GOR converter is lower than that of an AOD converter. The amount of savings varies depending on the grade of steel smelted. In addition, the GOR converter can precisely control the nitrogen content in the molten steel by blowing nitrogen into the molten pool. When smelting J series stainless steel, only a small amount of argon is used.

(3) From the point of view of production process: AOD furnace has high requirements on the composition of molten steel added to the electric furnace, slag removal is required before tapping, and part of the slag must be kept and poured into the ladle together with the molten steel from the furnace mouth; the GOR converter is added to the electric furnace. The composition requirements of the molten steel are not high (the carbon content is usually above 3%, and the silicon content is above 0.2%). Due to its large “furnace capacity ratio”, the decarburization rate is faster than that of the AOD furnace, and the degassing effect is relatively good. The bottom blowing nozzle of the GOR converter is close to the center line of the furnace, and the vibration of the furnace body is small during blowing; on the contrary, when the AOD furnace is blowing, the platform in front of the furnace feels obvious vibration. When the tilting speed of the converter is the same, the time from the start of tilting the furnace to the nozzle fully exposed to the liquid surface of the AOD furnace is shorter than that of the GOR converter, which is determined by the installation position of the nozzle. In the process of GOR blowing, no slag is removed, and the tapping hole is used for tapping, which is beneficial to the separation of the slag during the tapping of the converter, and the accurate control of the amount of slag entering the ladle, which is beneficial to the alloying of easily oxidized alloying elements such as titanium, but After adding the tapping hole, the furnace laying work is complicated. GOR theory blowing time is short, but a large amount of cold material needs to be added in the process to increase the blowing time. The higher the temperature of molten steel, the more serious the erosion of refractory materials.

(4) In terms of control ideas: AOD converter control software implements automatic control of the whole process from the initial molten steel into the converter. This kind of process software is very mature. As long as the raw materials are stable, ordinary technicians can operate independently after training; while the GOR converter allows manual intervention in the first stage of blowing, which can also be said to be extensive automatic control in this stage. When the carbon content in the molten steel is reduced to 0.25%, it is transferred to the second stage blowing, and the automatic control state is entered at this time. The advantage of this method is that it is more suitable for factories with complex and changeable raw material conditions.

The GOR converter can quickly complete refining tasks such as decarburization, deoxidation, degassing and alloying, and can also be used for dephosphorization if necessary. Since this process can adjust the composition of the mixed gas in a wide range, it can use molten steel provided by any melting furnace (such as induction furnace, electric arc furnace, etc.) as the refining raw material, and the mother liquor can be either unalloyed or Alloying can be carried out in a melting furnace.

The steel grades smelted by the GOR converter can currently be used for rolling strip, narrow strip, seamless steel pipe, bar, wire, and forgings with complex shapes. These primary products and their further processed products have good processing properties.

Selection of refractory materials for GOR converters

1. Selection of shaped refractory materials

Due to the long smelting time and high temperature of the GOR converter, a large amount of lime and scrap steel need to be added in the process to cool down, and the impact on the charging area of ​​the furnace body is severe, and the refractory material is required to have good high temperature strength; the basicity of the steel slag is from low to high, requiring slag The refractory material at the line has better resistance to low alkalinity, especially high alkalinity slag erosion. After repeated tests and production practices, it has been proved that magnesia-calcium refractories are suitable for the furnace shaft area.

Since a large amount of gas is blown in by the three lances at the bottom, the refractory material in the wind eye area of ​​the furnace bottom has to withstand the severe scouring of high-temperature molten steel, and the residual steel slag after tapping is deposited on the furnace bottom, so it is difficult to choose the refractory material for the furnace bottom. , requires good high temperature strength, good thermal shock resistance, low thermal expansion and good slag resistance.

2. Selection of unshaped refractory materials

(1) During the process of laying the furnace, the layer joints and vertical joints between the furnace bricks can be filled with 0.5-0mm magnesia powder.

(2) The gap around the furnace mouth and the tapping hole can be filled with plastic, and the material can be made of magnesium or high aluminum.

(3) High-quality ramming material can be selected for the seam between the furnace bottom brick and the furnace body brick after the furnace bottom is closed, and the material can be magnesia or magnesia-chromium.

(4) The annular seam between the furnace bottom brick and the furnace body brick after the heat exchange furnace bottom is not conducive to treatment. The selected bulk material requires good sinterability, good high temperature strength and corrosion resistance of high basicity slag. The material can be made of magnesium calcium or magnesium.

LMM YOTAI established in 2007. Our production technology comes from Japanese Yotai. As an experienced and international player in the refractories industry. We have succeeded in expanding both the breadth of its product range and the depth of its services. From raw material selection, refractory portofio & optimization, installation & services & recycle of used refractories on site to further reduce client’s Opex & Capex in refractory consumption per ton steel output, meanwhile improve product quality of client.

Our Product have been supplied to world’s top steel manufacturer Arcelormittal, TATA Steel, EZZ steel etc. We do OEM for Concast and Danieli for a long time

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