Duplex desilicication and manganese reduction method for top-bottom combined blown converter

Abstract

The invention relates to the technical field of iron and steel smelting, in particular to a duplex desilicication and manganese reduction method for a top-bottom combined blown converter, and solves the problem of high difficulty in smelting high-silicon and high-manganese molten iron by a dry dust removal converter under the current iron and steel smelting process conditions. According to the method, a traditional double-slag smelting mode is optimized, the mode is adjusted into a duplex method for smelting the high-silicon and high-manganese molten iron, the high-silicon and high-manganese molten iron is primarily smelted through one converter, silicon and manganese in the high-silicon and high-manganese molten iron are partially oxidized, the primarily smelted molten iron is put into a semi-steel ladle, semi-steel is added into another converter to be smelted again, and the high-silicon and high-manganese molten iron is obtained. According to the method, the consumption of auxiliary materials is greatly reduced, the metal loss caused by the deslagging frequency is reduced, the smelting process is stable, the abnormal conditions such as reaction gun lifting or splashing cannot occur, and the problem that the high-silicon high-manganese molten iron is difficult to smelt is fundamentally solved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a method for desiliconization and manganese reduction by a double-connection top and bottom combined blowing converter. Background Art

[0002] At present, the main method for smelting high-silicon and high-manganese molten iron in the converter in the industry is the double slag method. The double slag method is that high-silicon molten iron and scrap steel are added to the converter and then the gun is used for blowing. The first elements to participate in the oxidation reaction are Si, Mn, etc. The slag is discharged from the gun before the converter starts the carbon-oxygen reaction. This part of the converter slag is poured into the slag pot to reduce the Si and Mn content in the high-silicon molten iron. After the slag is discharged, the converter is lowered for a second time for re-slag smelting. The steelmaking converter uses dry dust removal. During the second gun blowing process, improper operation control can easily cause reaction gun lifting or splashing unloading explosion. Splashing not only causes a large amount of metal loss, but also easily causes equipment burns and scalds. Summary of the invention

[0003] The present invention provides a method for desiliconization and manganese reduction by a double-joint top and bottom combined blowing converter, so as to solve the problem that it is difficult to smelt high-silicon and high-manganese molten iron in a dry dust removal converter under the steel smelting process conditions in the above background.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A method for desiliconization and manganese reduction by a top and bottom combined blowing converter double process mainly includes the following processes: Step 1: When loading the converter, the total loading capacity of the converter is controlled to be 120t-130t, of which the scrap steel amount is controlled to be 10t-15t, and the molten iron is controlled to be 110t-115t.

[0005] Step 2. When the converter is supplied with oxygen, the working oxygen pressure is 0.65Mpa-0.75Mpa, the flow rate is 17000m³ / h-24000m³ / h, the oxygen pressure is set to 0.8MPa, and after the ignition is normal, the oxygen pressure is set to 0.65MPa-0.75Mpa, and the oxygen gun position control is executed in high-low-low mode. The gun position is controlled according to the measured gun position ≥800mm. After the ignition is successful and the oxygen supply time is greater than ≥1.5min, the gun position measurement control is 100mm-400mm, the oxygen supply time is 4min-8min, and the oxygen consumption is 2300m³ / furnace-2800m³ / furnace.

[0006] Step 3: When making slag in the converter, add 4t-6t of active lime, 2t-5t of limestone, 500kg-800kg of magnesium balls and 2t-6t of dust ash balls at one time after the ignition is normal.

[0007] Step 4: The final temperature of the converter is controlled at 1400°C-1500°C.

[0008] Step 5: When tapping the converter, a slag blocking cone is used to block the slag from tapping.

[0009] The present invention has the following beneficial effects: In a method for desiliconization and manganese reduction by a double-method of top and bottom combined blowing converter provided by the present invention, a converter performs primary smelting of high-silicon and high-manganese molten iron, first partially oxidizes the silicon and manganese in the high-silicon and high-manganese molten iron, puts the initially smelted molten iron into a semi-steel ladle, and then adds the semi-steel into another converter for re-smelting. This mode not only greatly reduces the consumption of auxiliary materials and reduces the metal loss caused by the number of slag pouring, but also ensures a stable smelting process without abnormal situations such as reaction gun lifting or splashing. It fundamentally solves the problem of difficulty in smelting high-silicon and high-manganese molten iron, effectively reduces the loss of metal in converter smelting, and is conducive to reducing production costs. DETAILED DESCRIPTION

[0010] The present invention will be further described below in conjunction with specific embodiments.

[0011] Example 1: A method for desiliconization and manganese reduction by a double-linked method of a 120-ton top and bottom combined blowing converter, comprising the following steps: Step 1. Loading the converter: A 120-ton top and bottom double-blown converter is loaded with 110 tons of molten iron and 10 tons of scrap steel. The molten iron contains 4.56% C, 2.5% Si, 0.105% Mn, 0.093% P, 0.02% S, and about 92.37% Fe. Other uncontrollable elements such as Bi, Pb, Sb, As, Sn and other trace elements account for about 0.385%. The temperature of the molten iron entering the furnace is 1270°C.

[0012] Step 2, oxygen supply to converter: set the oxygen pressure at 0.8MPa. After the ignition is normal, adjust the oxygen pressure to 0.65MPa, control the oxygen flow rate at 17000 m³ / h, and control the gun position at 800mm according to the measured gun position. After the ignition is successful and the oxygen is supplied for 1.5min, the gun position is controlled at 100mm according to the measured gun position. The oxygen consumption is 2300 m³ / furnace. When the gas analyzer shows that the CO content reaches 6%, lift the gun. The oxygen supply time is 4min.

[0013] Step 3, converter slag making: after the ignition is normal, add 4t of active lime, 2t of limestone, 500kg of magnesium balls and 2t of dust ash pellets at one time.

[0014] Step 4: Converter temperature control: Measure the temperature during slag pouring, the converter pouring temperature is 1400℃.

[0015] Step 5, tapping from converter: The tapping is done by using slag blocking cone, and the semi-steel molten steel volume is 122 t.

[0016] In this embodiment, the C content of semi-steel reaches 2.9%, Si is reduced to 0.3%, Mn is reduced to 0.6%, P accounts for 0.07%, and S accounts for 0.04%. The dual-process achieves desiliconization and manganese reduction.

[0017] Example 2: A method for removing silicon and reducing manganese by a double-process of a 120-ton top and bottom combined blowing converter, comprising the following steps: Step 1. Loading the converter: A 120-ton top and bottom blown converter is loaded with 112 tons of molten iron and 13 tons of scrap steel. The molten iron contains 4.8% C, 1.63% Si, 0.113% Mn, 0.135% P, 0.011% S, about 93% Fe, and other uncontrollable elements such as Bi, Pb, Sb, As, Sn and other trace elements account for about 0.385%. The temperature of the molten iron entering the furnace is 1280°C.

[0018] Step 2, oxygen supply to converter: set the oxygen pressure at 0.8MPa. After the ignition is normal, adjust the oxygen pressure to 0.70MPa, control the oxygen flow rate at 20000 m³ / h, and control the gun position according to the measured gun position of 810mm. After the ignition is successful and the oxygen is supplied for 2min, the gun position is controlled according to the measured gun position of 250mm. The oxygen consumption is 2700 m³ / furnace. When the gas analyzer shows that the CO content reaches 6.5%, lift the gun and supply oxygen for 6min.

[0019] Step 3, converter slag making: after the ignition is normal, add 5t of active lime, 3t of limestone, 700kg of magnesium balls and 5t of dust ash pellets at one time.

[0020] Step 4: Converter temperature control: Measure slag pouring temperature, converter pouring temperature is 1475℃.

[0021] Step 5, tapping from converter: The tapping is done by using slag blocking cone, and the semi-steel molten steel volume is 123.5 t.

[0022] In this embodiment, the C content of semi-steel reaches 3.22%, Si is reduced to 0.4%, Mn is reduced to 0.8%, P accounts for 0.07%, and S accounts for 0.03%. The dual-combination method achieves desiliconization and manganese reduction.

[0023] Example 3: A method for desiliconization and manganese reduction by a double-process of a 120-ton top and bottom combined blowing converter, comprising the following steps: Step 1. Loading the converter: A 120-ton top and bottom double-blown converter is loaded with 115 tons of molten iron and 12 tons of scrap steel. The molten iron contains 4.73% C, 1.15% Si, 0.121% Mn, 0.100% P, 0.019% S, and about 93.5% Fe. Other uncontrollable elements such as Bi, Pb, Sb, As, Sn and other trace elements account for about 0.385%. The temperature of the molten iron entering the furnace is 1285°C.

[0024] Step 2, oxygen supply to converter: set the oxygen pressure at the start of blowing to 0.8MPa. After the blowing and ignition are normal, adjust the oxygen pressure to 0.75MPa, control the oxygen flow rate at 24000 m³ / h, and control the blowing gun position according to the measured gun position of 820mm. After successful ignition and oxygen supply for 2min, the gun position is controlled according to the measured gun position of 270mm. The oxygen consumption is 2800 m³ / furnace. When the gas analyzer shows that the CO content reaches 6%, lift the gun and supply oxygen for 8min.

[0025] Step 3, converter slag making: after the ignition is normal, add 6t of active lime, 5t of limestone, 800kg of magnesium balls and 6t of dust ash pellets at one time.

[0026] Step 4: Converter temperature control: Measure the temperature during slag pouring, and the converter pouring temperature is 1500℃.

[0027] Step 5, converter tapping: The tapping adopts slag blocking cone, and the semi-steel molten steel volume is 124 t.

[0028] In this embodiment, the C content of the semi-steel reaches 3.15%, Si is reduced to 0.45%, Mn is reduced to 0.4%, P accounts for 0.065%, and S accounts for 0.02%. The dual-combination method achieves desiliconization and manganese reduction.

Claims

1. A method for desiliconization and manganese reduction by a top and bottom combined blowing converter double process, characterized in that: The main processes are as follows: Step 1: When loading the converter, the total loading capacity of the converter is controlled to be 120t-130t, of which the scrap steel amount is controlled to be 10t-15t, and the molten iron is controlled to be 110t-115t; Step 2, when the converter is supplied with oxygen, the working oxygen pressure is 0.65Mpa-0.75Mpa, the flow rate is 17000m³ / h-24000m³ / h, the oxygen pressure is set to 0.8MPa, and after the ignition is normal, the oxygen pressure is set to 0.65MPa-0.75Mpa, and the oxygen gun position control is executed in high-low-low mode. The gun position is controlled according to the measured gun position ≥800mm. After the ignition is successful and the oxygen supply time is greater than ≥1.5min, the gun position measurement control is 100mm-400mm, the oxygen supply time is 4min-8min, and the oxygen consumption is 2300m³ / furnace-2800m³ / furnace; Step 3, when making slag in the converter, after the ignition is normal, add 4t-6t of active lime, 2t-5t of limestone, 500kg-800kg of magnesium balls, and 2t-6t of dust ash balls at one time; Step 4: The final temperature of the converter is controlled to be 1400°C-1500°C; Step 5: When tapping the converter, a slag blocking cone is used to block the slag from tapping.