A method for preparing micro-rare earth steel by rare earth synthetic slag

Abstract

The application discloses a method for preparing micro-rare earth steel by using rare earth synthetic slag, and aims at Baotou ore which is a rare earth resource, and utilizes the rare earth in the ore after iron smelting to reduce the blast furnace slag, adds a certain reducing agent material to synthesize the refining slag, and adds the refining slag into a refining process, so that the rare earth in the synthetic slag is combined into the molten steel in the reducing atmosphere, so as to form the rare earth micro-alloyed steel. The application realizes the reutilization of the rare earth blast furnace slag resource, and mass industrial production of the micro-rare earth steel.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel smelting, and particularly relates to a method for preparing micro-rare earth steel by using rare earth synthetic slag. BACKGROUND

[0002] Baotou Steel Group is rich in rare earth resources, and the ore is the main source of iron ore for steel production. After sintering and pelletizing of high-proportioned Baiyun ore, the rare earth in the raw material mainly enters the blast furnace slag in the form of rare earth oxide, and its content is determined by the proportion of local ore in the raw material. According to the metallurgical function and physical and chemical properties of the slag in the steelmaking process, the rare earth oxide in the slag is added to the slag to form a refining slag with a rare earth direct alloying function in the refining process. Under the premise of ensuring the refining function, the rare earth in the slag is reduced into the steel. The alloying process avoids the oxidation atmosphere of the converter blowing process, and uses the reducing atmosphere of the refining process to produce rare earth steel with part of the rare earth elements in the blast furnace slag. This can reasonably utilize the blast furnace slag resources of Baotou Steel, simplify the rare earth addition process, uniform the rare earth composition in the steel, improve the castability of the rare earth steel, reduce the production cost, and realize the reutilization of rare earth oxide in solid waste. SUMMARY

[0003] The purpose of the present application is to provide a method for preparing micro-rare earth steel by using rare earth synthetic slag. The rare earth in the ore after iron smelting is reduced to the blast furnace slag, and a certain reducing agent material is added to the synthetic slag to form a refining slag. The rare earth in the synthetic slag is introduced into the molten steel in the refining reducing atmosphere, so as to form a rare earth micro-alloyed steel.

[0004] To solve the above technical problems, the present application adopts the following technical scheme:

[0005] The present application provides a method for preparing micro-rare earth steel by using rare earth synthetic slag, which comprises the following steps:

[0006] 1) Preparation of blast furnace slag synthetic slag: the blast furnace slag is ground into powder, 0.2-0.24% of aluminum powder is added, and synthetic pellets are prepared, each pellet being 25-35mm; a certain batch of synthetic slag is prepared;

[0007] 2) In the converter tapping process: the slide plate is used to block the slag, the amount of slag discharged from the converter is controlled, and 280-320kg / ton of small particle white ash is added during the tapping process;

[0008] 3) In the LF, 60-90kg of aluminum particles are added to remove slag, 25-35kg of silicon barium calcium is added, the content of [Al] in the molten steel is controlled to be 0.01%-0.020%, and the content of [Ca] is controlled to be 0.002%-0.005%;

[0009] 4) In the LF, add a proper amount of blast furnace slag synthetic slag, and add lime according to the refining basicity requirement; according to the LF slag fluidity, add 50-100 kg of fluorite ball;

[0010] 5) In the LF process, ensure that the soft blowing time is greater than or equal to 10 min, adjust the flow according to the actual soft blowing effect, ensure that the molten steel is not exposed, reduce the air absorption and secondary oxidation, and ensure the normal refining time and the normal setting time of the test steel;

[0011] 6) Before leaving the refining, sample and determine the rare earth content in the steel, realize the reutilization of the rare earth blast furnace slag resource, and batch industrially prepare the micro-rare earth steel.

[0012] Further, 0.22% of aluminum powder is added.

[0013] Further, each ball 28-32mm.

[0014] Further, 300kg / oven small particle lime is added in the tapping process.

[0015] Further, the mass percentage of the components of the blast furnace slag synthetic slag includes: CaO 35.45%, F 0.531%, S 1.36%, SiO2 30.50%, MgO 8.09%, CeO2 1.59%, Al2O3 11.96%, La2O3 0.870%, and P <0.050%.

[0016] Further, the mass percentage of the components of the blast furnace slag synthetic slag includes: CaO 35.27%, F 0.692%, S 1.35%, SiO2 29.69%, MgO 8.06%, CeO2 1.74%, Al2O3 11.24%, La2O3 0.970%, and P <0.050%.

[0017] Further, 1-2t of the blast furnace slag synthetic slag is added per furnace.

[0018] Compared with the prior art, the beneficial technical effects of the present application are:

[0019] The present application realizes the reutilization of the rare earth blast furnace slag resource and batch industrially prepares the micro-rare earth steel by the method for preparing the micro-rare earth steel through the rare earth synthetic slag. DETAILED DESCRIPTION

[0020] A method for preparing a micro-rare earth steel through a rare earth synthetic slag, which adopts a synthetic blast furnace refining slag to perform an industrialized preparation process of the micro-rare earth steel, and the process flow is as follows:

[0021] 1) First, prepare a blast furnace slag synthetic slag: grind the blast furnace slag into powder, add 0.22% of aluminum powder, and synthesize a ball, each ball being about 30mm. Prepare a certain batch of synthetic slag, and the specific components are shown in Table 1.

[0022] 2) In the converter tapping: slide plate slag, control the amount of converter tapping slag, add 300 kg / furnace small particle lime in the tapping process.

[0023] 3) In the LF in place, add 60-90 kg aluminum particles to deslagging, add 30 kg of silicon barium calcium, control the [Al] content of molten steel target is 0.01%-0.020%; [Ca] content target is 0.002%-0.005%.

[0024] 4) In the LF, add an appropriate amount of blast furnace slag synthetic slag, and add lime according to the refining basicity requirement. Add an appropriate amount of fluorite ball 50-100 kg according to the LF slag fluidity.

[0025] 5) In the LF process, ensure the soft blowing time ≥10 min, adjust the flow according to the actual soft blowing effect, ensure that the molten steel is not exposed, reduce the air absorption and secondary oxidation, and ensure the normal refining time and setting time of the test steel.

[0026] 6) Take a sample to measure the rare earth content in the steel before leaving the refining, realize the reuse of rare earth blast furnace slag resources, and batch industrialize the preparation of micro-rare earth steel.

[0027] Table 1 Blast furnace slag synthetic slag

[0028] CaO F S SiO2 MgO CeO2 Al2O3 La2O3 P 35.45 0.531 1.36 30.50 8.09 1.59 11.96 0.870 <0.050 35.27 0.692 1.35 29.69 8.06 1.74 11.24 0.970 <0.050

[0029] Application case

[0030] A steelmaking plant uses the above content process to produce micro-rare earth steel. Among them, 1.5 t of blast furnace slag synthetic slag is added per furnace, 3 furnaces are continuously produced, the rare earth content is measured before leaving the refining, and the average of the measurement results is 5 ppm. Batch industrialization of micro-rare earth steel is prepared.

[0031] The above-described embodiments are only to describe the preferred modes of the present application, and not to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for preparing low-rare earth steel by using rare earth synthetic slag, characterized in that: Comprise: 1) preparation of blast furnace slag synthetic slag: take blast furnace slag grinding into powder, add 0.2-0.24% aluminum powder, synthetic balling, each ball 25-35mm; preparation of a certain batch of synthetic slag; 2) in the converter tapping: slide plate slag, control the converter tapping slag, add 280-320kg / furnace small particle lime in the process of tapping; 3) in LF in place plus 60-90kg aluminum particle deslagging oxygen, plus silicon barium calcium 25-35kg, control the molten steel [Al] content target is 0.01%-0.020%; [Ca] content target is 0.002%-0.005%; 4) in LF, add appropriate amount of blast furnace slag synthetic slag, 1-2t of blast furnace slag synthetic slag per furnace; lime is added according to the requirement of refining basicity; according to the LF slag fluidity, add fluorite ball 50-100kg; 5) in LF process, ensure soft blowing time ≥10min, adjust the flow according to the actual soft blowing effect, ensure that the molten steel is not exposed, reduce the air absorption and secondary oxidation, ensure the normal refining time and setting time of the test steel; 6) before leaving the refining, sampling to determine the rare earth content in the steel, realizing the recycling of rare earth blast furnace slag resources, and preparing micro rare earth steel in batches; The mass percentage composition of blast furnace slag synthetic slag includes: CaO 35.45%, F 0.531%, S 1.36%, SiO230.50%, MgO 8.09%, CeO2 1.59%, Al2O3 11.96%, La2O3 0.870%, P<0.050%; Or, the mass percentage composition of blast furnace slag synthetic slag includes: CaO 35.27%, F 0.692%, S 1.35%, SiO229.69%, MgO 8.06%, CeO2 1.74%, Al2O3 11.24%, La2O3 0.970%, P<0.050%.

2. The method for preparing a micro-rare earth steel by a rare earth synthetic slag according to claim 1, characterized in that, Add 0.22% aluminum powder.

3. The method of producing micro-rare earth steel by rare earth synthetic slag according to claim 1, characterized in that, Each ball 28-32mm.

4. The method of producing micro-rare earth steel by rare earth synthetic slag according to claim 1, characterized in that, Add 300kg / furnace small particle lime in the process of tapping.