Method for making slag by replacing partial limestone with lime used for top and bottom combined blown converter

A top-bottom re-blowing, limestone technology, applied in the direction of manufacturing converters, etc., can solve the problems of undescribed oxygen supply operation, limestone particle size dephosphorization, change of desulfurization rate, slow slag formation speed, and reduction of calorific value of converter gas recovered.

Inactive Publication Date: 2012-10-10
LAIWU IRON & STEEL GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First, the slagging speed is slow, limestone needs to be decomposed into CaO first, and then participate in the reaction
Second, the decomposition process needs to absorb heat, which will cause insufficient heat in the converter and further affect the effect of slagging
This method introduces the use of part of limestone instead of lime to make slag in the top-blown converter, and the addition of limestone is divided into 4-8 batches, and small batches are added in multiple batches to reduce the difficulty of limestone slagging. The amount of slag is added frequently, which is not mentioned in the patent Effect of the method on converter gas, CO produced after process addition 2 It will reduce the CO concentration in the furnace gas and reduce the calorific value of the gas recovered by the converter; the patent does not describe specific data such as oxygen supply operation, limestone particle size, dephosphorization after use, and changes in desulfurization rate

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Add 90t of molten iron, 3t of steel scrap and 1t of iron block into the 80t converter, molten iron C: 4.0wt%, Si: 0.90wt%, Mn: 0.25wt%, P: 0.153wt%, S: 0.037%wt%, molten iron temperature 1350 ℃. Start oxygen supply and add 3t of limestone at the same time, the amount of lime added in the first batch will be reduced by 1t accordingly, after 3 minutes, the amount of lime added in the second batch will be reduced by 500kg, and the cumulative amount of lime added will be reduced by 1.5t. Bottom blowing flow rate 0.07Nm during the first 0-3 minutes 3 / min·t, open blow gun position 1200mm, oxygen pressure 0.85MPa, operate according to the original smelting process after 3 minutes. The oxygen supply was stopped for 14 minutes, the temperature of the molten steel was measured at 1616°C, and the components of the molten steel were C: 0.22wt%, P: 0.011wt%, and S: 0.016wt%. The composition is qualified, when the furnace dephosphorization rate reaches 92.8wt%, the desulfurization...

Embodiment 2

[0025] Add 90t of molten iron, 3t of steel scrap and 1t of iron block into the 80t converter, molten iron C: 4.0wt%, Si: 0.37wt%, Mn: 0.25wt%, P: 0.155wt%, S: 0.035wt%, and the temperature of the molten iron is 1298°C . Start oxygen supply and add 1t of limestone at the same time, the amount of lime added in the first batch will be reduced by 500kg accordingly. Bottom blowing flow rate 0.05Nm during the first 0-3 minutes 3 / min·t, open blow gun position 1200mm, oxygen pressure 0.85MPa, operate according to the original smelting process after 3 minutes. The oxygen supply was stopped for 14 minutes, the temperature of the molten steel was measured at 1627°C, and the components of the molten steel were C: 0.31wt%, P: 0.021wt%, and S: 0.016wt%. The composition is qualified, when the dephosphorization rate of the furnace reaches 86.4wt%, the desulfurization rate reaches 54wt%, the oxygen consumption is 51.7M3 / t, and the CO concentration of the recovered gas is 49.17wt%.

Embodiment 3

[0027]Add 90t of molten iron, 3t of steel scrap and 1t of iron block into the 80t converter, molten iron C: 4.0wt%, Si: 0.66wt%, Mn: 0.27wt%, P: 0.172wt%, S: 0.048wt%, and the temperature of the molten iron is 1268°C . Start the oxygen supply and add 2t of limestone at the same time, and the amount of the first batch of lime should be reduced by 1t accordingly. Bottom blowing flow rate 0.06Nm during the first 0-3 minutes 3 / min·t, open blow gun position 1150mm, oxygen pressure 0.90MPa, operate according to the original smelting process after 3 minutes. The oxygen supply was stopped for 14 minutes, the temperature of the molten steel was measured at 1630°C, and the components of the molten steel were C: 0.11wt%, P: 0.015wt%, and S: 0.022wt%. The composition is qualified, when the dephosphorization rate of the furnace reaches 91.3wt%, the desulfurization rate reaches 54.2wt%, the oxygen consumption is 53.5M3 / t, and the CO concentration of recovered gas is 54.8wt%.

[0028] Th...

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Abstract

The invention provides a method for making slag by replacing partial limestone with lime used for a top and bottom combined blown converter. According to the invention, when the stainless is smelted by using the top and bottom combined blown converter, the partial limestone is used for replacing the lime, wherein, all the limestone is added at a time before blowing oxygen, the particle size of the limestone is between 5 and 20mm, and the addition of the limestone is 5-30kg/t of steel. The method for making slag by replacing the partial limestone with lime used for the top and bottom combined blown converter enables fast slagging, and is beneficial to converter dephosphorizing.

Description

technical field [0001] The invention relates to the field of converter steelmaking, and more specifically relates to a method for making slag in a top-bottom combined blowing converter using part of limestone instead of lime. Background technique [0002] The traditional top-bottom combined blowing converter uses active lime to make slag, and its CaO content reaches more than 80%. The CaO in the active lime is used to oxidize the molten iron to form SiO 2 ,P 2 o 5 After the acidic oxides are combined, they enter the slag to achieve the purpose of removing Si, P, S and other elements from the molten iron. [0003] Lime is produced by calcination of limestone, the reaction is: CaCO 3 →CaO+CO 2 Generally, the limestone is heated at 1050-1150°C, and after being calcined for several hours, it is decomposed to obtain lime. According to the calcination conditions of lime, generally the lime obtained by controlling the temperature at about 1100°C with fine grains, high porosity...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C5/36
Inventor 王广连申景霞王显军陈良尹崇丽魏潇
Owner LAIWU IRON & STEEL GRP
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