阅读说明：本技术 一种提高含铌废料中铌回收率的冶炼方法 (Smelting method for improving recovery rate of niobium in niobium-containing waste ) 是由 马红军 舒美良 吴振忠 徐涛 黄日圣 陈伟生 江鲜庚 程建鹏 章静能 章良刚 于 2020-12-07 设计创作，主要内容包括：本发明公开了一种提高含铌废料中铌回收率的冶炼方法,涉及金属冶炼技术领域,该方法在冶炼过程中使用含铌废料,并控制配料中硅含量在1.2％～1.5％范围内,然后向电弧炉内加入炉料,控制炉渣成分为38％～43％的CaO、25％～28％的SiO-2、5％～8％的MgO和4％～10％的Al-2O-3,剩余的为其它杂质,且炉渣二元碱度为1.2～1.5；然后进行出钢作业,令钢液和炉渣一起兑入AOD炉内；AOD炉用底吹氩气搅拌3min,之后扒除全部炉渣,然后根据最终产物成分配比向AOD炉内配加合金进行脱碳升温作业,预还原加入硅铁和造渣材料,氩气搅拌5min,控制炉渣成分为50％～60％的CaO、10％～15％的SiO-2、5％～10％的MgO、3％～8％的Al-2O-3、5％～10％的CaF,剩余的为其它杂质,且炉渣四元碱度为3.0～3.4；然后进行扒渣作业,扒渣之后进行还原出钢；本发明可有效提高含铌废料中铌的回收率。(The invention discloses a smelting method for improving the recovery rate of niobium in niobium-containing waste, which relates to the technical field of metal smelting, and the method uses the niobium-containing waste in the smelting process, controls the silicon content in ingredients within the range of 1.2-1.5%, then adds furnace burden into an electric arc furnace, controls the slag components to be 38-43% of CaO and 25-28% of SiO 2 5 to 8 percent of MgO and 4 to 10 percent of Al 2 O 3 The rest is other impurities, and the binary alkalinity of the slag is 1.2-1.5; then carrying out tapping operation, and adding the molten steel and the slag into the AOD furnace; stirring for 3min by bottom blowing argon gas for AOD furnace, removing all furnace slag, adding alloy into AOD furnace according to the component ratio of final product to perform decarburization and heating operation, adding ferrosilicon and slagging material for prereduction, stirring for 5min by argon gas, and controlling the furnace slag component to be 50%60 percent of CaO and 10 to 15 percent of SiO 2 5 to 10 percent of MgO and 3 to 8 percent of Al 2 O 3 5 to 10 percent of CaF, the rest is other impurities, and the quaternary alkalinity of the furnace slag is 3.0 to 3.4; then carrying out slag skimming operation, and carrying out reduction tapping after slag skimming; the method can effectively improve the recovery rate of niobium in the niobium-containing waste.)

1. A smelting process for increasing the recovery of niobium from a niobium-containing waste material, which comprises using the niobium-containing waste material in a process for producing a steel material of a niobium-containing steel product as a final product, and which comprises the steps of:

step 1, in the process of preparing smelting materials required by a final product, niobium-containing waste materials are used as ingredients, the silicon content in the ingredients is controlled within the range of 1.2% -1.5%, then furnace burden is added into an electric arc furnace, and the slag components are controlled to be 38% -43% of CaO and 25% -28% of SiO₂5 to 8 percent of MgO and 4 to 10 percent of Al₂O₃The rest is other impurities, and the binary alkalinity of the slag is 1.2-1.5; then carrying out tapping operation, and adding the molten steel and the slag into the AOD furnace;

and 2, stirring the AOD furnace by bottom blowing argon for 3min, removing all furnace slag, then adding alloy into the AOD furnace according to the component proportion of a final product to perform decarburization and heating operation, pre-reducing and adding ferrosilicon and a slagging material, stirring the argon for 5min, and controlling the furnace slag components to be 50-60% of CaO and 10-15% of SiO₂5 to 10 percent of MgO and 3 to 8 percent of Al₂O₃5 to 10 percent of CaF, the rest is other impurities, and the quaternary alkalinity of the furnace slag is 3.0 to 3.4; and then carrying out slag skimming, and carrying out reduction tapping after slag skimming.

2. The method of claim 1, wherein step 1, after charging the electric arc furnace, further comprises cutting the refractory scrap with oxygen after melting 1/2 of the charge, and blowing carbon powder at the oxygen blowing position to reduce oxidation and then controlling slag composition.

3. The method of claim 2, wherein the molten steel and slag are transferred into the AOD furnace through a ladle during tapping in the electric arc furnace of step 1.

4. The method of claim 3, wherein the final product is TP347H austenitic stainless steel.

Technical Field

The invention relates to the technical field of metal smelting, in particular to a smelting method for improving the recovery rate of niobium.

Background

The stainless steel mainly contains Cr, and in order to improve the intergranular corrosion resistance and mechanical property of the material, part of the stainless steel is added with niobium. Because the metal activity of niobium is equivalent to that of Cr, niobium oxide can be generated by combining oxygen in the smelting process of stainless steel and enters into slag. The stainless steel slag contains a certain amount of Cr oxide, so that niobium in the slag is difficult to reduce, and the recovery rate of niobium is reduced.

Niobium in the stainless steel belongs to precious metals, the value of the niobium is about 4 times that of Ni and about 30 times that of Cr, the recovery rate of niobium is improved, and the niobium-containing stainless steel has an important effect on reducing the smelting cost of the niobium-containing stainless steel.

With the gradual improvement of stainless steel waste classification work in the stainless steel waste market, the problem of recovering niobium element in the niobium-containing stainless steel waste is increasingly outstanding, and the niobium-containing stainless steel waste has great potential economic value.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, and provides a smelting method for improving the recovery rate of niobium in niobium-containing waste materials, so as to solve the technical problem that the niobium-containing waste materials are difficult to be reused in the prior art.

The invention is realized by the following technical scheme:

a smelting process for increasing the recovery of niobium from a niobium-containing waste material, which process comprises using the niobium-containing waste material in a process for producing a steel material of a niobium-containing steel product as a final product, and which comprises the steps of, in the smelting process:

step 1, in the process of preparing smelting materials required by a final product, niobium-containing waste materials are used as ingredients, the silicon content in the ingredients is controlled within the range of 1.2% -1.5%, then furnace burden is added into an electric arc furnace, and the slag components are controlled to be 38% -43% of CaO and 25% -28% of SiO₂5 to 8 percent of MgO and 4 to 10 percent of Al₂O₃The rest is other impurities, and the binary alkalinity of the slag is 1.2-1.5; then carrying out tapping operation, and adding the molten steel and the slag into the AOD furnace;

and 2, stirring the AOD furnace by bottom blowing argon for 3min, removing all furnace slag, then adding alloy into the AOD furnace according to the component proportion of a final product to perform decarburization and heating operation, pre-reducing and adding ferrosilicon and a slagging material, stirring the argon for 5min, and controlling the furnace slag components to be 50-60% of CaO and 10-15% of SiO₂5 to 10 percent of MgO and 3 to 8 percent of Al₂O₃5 to 10 percent of CaF, the rest is other impurities, and the quaternary alkalinity of the furnace slag is 3.0 to 3.4; and then carrying out slag skimming, and carrying out reduction tapping after slag skimming.

Further, the step 1 includes cutting the refractory waste material by using oxygen after the charging materials are melted 1/2 after the charging materials are charged into the electric arc furnace, simultaneously blowing carbon powder at an oxygen blowing position to reduce oxidation, and then controlling slag components.

Further, molten steel and furnace slag are transferred into the AOD furnace through a steel ladle during tapping of the electric arc furnace in the step 1.

Further, the final product was TP347H austenitic stainless steel.

Compared with the prior art, the invention has the following advantages:

according to the invention, the Nb-containing waste material is used as a raw material, lime and a slagging material are added in the smelting process of an electric arc furnace, and the alkalinity of the slag is controlled to be 1.2-1.5; the slag and the molten steel are added into the AOD furnace together to be stirred and smelted for 3min, so that the recovery rate of Nb in the return material can reach more than 97 percent on the premise of not increasing the equipment investment, and the production cost is effectively reduced.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides a smelting method for improving the recovery rate of Nb in Nb-containing waste. Mainly aims at the problem of recovering Nb in Nb-containing waste. The method mainly comprises the following steps: 1. using Nb-containing waste materials for batching; 2. adding lime and slagging materials in the smelting process of an electric arc furnace, and controlling the alkalinity of slag to be 1.2-1.5; 3. tapping with slag in an electric arc furnace, and adding the slag and molten steel into an AOD furnace for smelting; 4. stirring in an AOD furnace for about 3min, and removing slag brought by an electric arc furnace; 5. the pre-reduction alkalinity of AOD is controlled to be 3.0-3.4, and fluorite can be used for slagging.

The main way of oxidation of Nb element is to react with blown oxygen to produce Nb oxide.

Nb+[O]→NbO₂ (1)

NbO₂Floating up to enter the slag. Because the slag also contains Cr₂O₃Result in NbO₂The difficulty of being reduced is high.

The procedures needing oxygen blowing in the whole smelting process comprise electric arc furnace oxygen blowing fluxing and AOD oxygen blowing decarburization, so the research of improving the recovery of Nb element is mainly carried out from the two oxygen blowing procedures.

The main chemical reactions for the recovery of Nb are:

(NbO₂)+Si→Nb+(SiO₂) (2)

to enable this reaction to proceed to the right, first: required slag Cr₂O₃The content is as low as possible, since Nb has a chemical nature comparable to Cr, and Cr is present in high-temperature metallurgical conditions₂O₃Will undergo a displacement reaction with the Nb and,

Cr₂O₃+Nb→Cr+NbO₂ (3)

(3) reaction No. 2 seriously affects the rightward progress of reaction No. 2.

Second, there is a need to reduce SiO in slag₂The percentage content of (A) is as follows. The main method is to add slag-making material into the furnace and increase the basicity of the slag to reduce SiO₂The percentage content of (A) is as follows.

In the smelting process of stainless steel, due to the characteristics of an electric arc furnace and an AOD furnace, the alkalinity of the slag cannot be increased without limit, and the matching of the alkalinity and the fluidity of the slag needs to be adjusted in the smelting process, so that the slag achieves the best reduction effect.

In the smelting process of the electric arc furnace, almost no stirring function exists, when stainless steel containing Nb waste is smelted, the alkalinity of furnace slag needs to be controlled to be about 1.2-1.5, the alkalinity is too high, the stirring function is lacked, the fluidity of the furnace slag is poor, and various reactions in the furnace slag can be weakened. Through field tests, the slag system of the electric arc furnace is controlled within the range shown in the table 1, and the oxidation of Nb in the scrap can be reduced.

TABLE 1

The slag system has good slag fluidity under the smelting condition of an electric arc furnace, and has certain reduction capability and furnace wall protection capability.

The oxygen blowing of the electric arc furnace has the main functions of promoting the melting of furnace charge, shortening the smelting time and reducing the production cost. In order to reduce as much as possible the amount of Nb component in the oxygen-oxidized charge blown in, it is necessary to control the amount of Nb component in the charge from the following points:

(1) during the material preparation, ferrosilicon is properly added, and Si in the furnace charge is added to 1.2-1.5%, so that the reducibility of the molten steel is improved.

(2) When oxygen is blown, the oxygen mainly cuts the unmelted waste materials and can not go deep into the molten steel;

(3) carbon powder is sprayed into the oxygen outlet while oxygen is blown, so that the carbon at the oxygen outlet is improvedIn an amount such that oxygen preferentially reacts with carbon powder to form CO₂And heat is generated to assist the melting of the furnace burden.

Because the stirring intensity in the electric arc furnace is insufficient, the interactive reaction intensity among the steel slag is insufficient to completely reduce the Nb oxide in the slag, and after the electric arc furnace discharges steel, a certain amount of Nb oxide exists in the slag, molten steel discharged from the electric arc furnace and the slag are required to be added into the AOD furnace together, and the bottom blowing of the AOD furnace is utilized to intensively stir and reduce the Nb oxide in part of the slag by residual Si in the molten steel.

The AOD smelting step is divided into three stages of a decarburization heating period, a pre-reduction period and a reduction period, wherein the decarburization heating period mainly removes C in molten steel to meet the steel grade target requirement, and the decarburization heating period mainly uses oxygen for blowing, so that oxidation of Nb is caused, and Nb oxide is generated and enters furnace slag. And after the decarburization heating period is finished, ferrosilicon is added for reduction. In order to increase the recovery rate of Nb, it is necessary to strictly control the slag system of the slag at this time, including indexes such as basicity, main components, and fluidity of the slag. According to field practice, the AOD pre-reduction slag system is in the range required by the table 2, and the recovery rate of Nb can be stabilized to be more than 97%.

TABLE 2

CaF is mainly used to adjust the fluidity of the slag.

After ferrosilicon and slagging materials are added in the prereduction, stirring is carried out for 5min by argon, prereduced furnace slag is removed, and slagging and smelting are carried out again.

Benefit of

The invention aims at the problem of recycling Nb in Nb-containing waste. Adding lime and slagging materials in the smelting process of an electric arc furnace by using Nb-containing waste materials, and controlling the alkalinity of slag to be 1.2-1.5; the furnace slag and the molten steel are added into the AOD furnace together to be melted with fluorite, stirred and smelted for 3min, so that the recovery of Nb in the return material can reach more than 97 percent on the premise of not increasing the equipment investment, and the production cost is effectively reduced.

The method comprises the following specific implementation steps:

a35 t arc furnace, 35tAOD argon oxygen fining furnace, TP347H austenitic stainless steel is exemplified.

The main chemical element components of TP347H are shown in Table 3:

TABLE 3

The content of Nb is 8-1.10, the content of C is generally controlled to be about 0.075%, and the content of Nb is controlled to be 0.6% -1.10%.

The material is made up by using Nb-containing waste as main raw material and adding necessary Cr and Ni alloy, so that the material composition of Cr and Ni elements can be up to the lower limit of target composition of steel grade. The weight of the mixture is 32t, the content of Nb in the mixture is 0.42 percent, and the content of Si in the mixture is 1.35 percent.

The furnace burden is added into the electric arc furnace according to batches, after each pot of furnace burden is added into the electric arc furnace, the furnace burden is melted above 1/2, oxygen is adopted to cut refractory waste, and carbon powder is simultaneously blown at an oxygen blowing position to reduce oxidation. After each tank of material is completely melted, slag is adjusted by adding slag-forming materials according to the condition of the slag. And after the furnace burden is completely melted, taking a furnace slag sample for testing, carrying out tapping operation after the components of the furnace slag meet the requirements of the table 1, and discharging the molten steel and the furnace slag into a steel ladle together.

Molten steel and slag tapped from the electric arc furnace are added into an AOD furnace, argon is blown from the bottom of the AOD furnace to stir for about 3min, then all the slag is sampled and analyzed, the weight of the molten steel after slag removal is 31.2t, and the Nb content in the molten steel is 0.43%.

After AOD slagging-off, adding alloy except Nb alloy for 1.5t according to the component distribution, carrying out decarburization heating operation, pre-reducing, adding ferrosilicon and slagging material, stirring for 5min by argon, taking a slag sample for assay, wherein the slag component meets the requirement of table 2, slagging-off operation can be carried out, and taking a molten steel sample for assay, and assaying the Nb component by 0.402%. And adding Nb alloy after slagging off, and controlling the Nb element to meet the target requirement of steel grade and then normally reducing and tapping.

Calculating the Nb recovery rate in the waste: [ (31.2+1.5) × 0.402% ]/(32 × 0.42%) × 100% -, 97.8%

By controlling the components of the molten steel and the slag in each process, the recovery rate of Nb in the waste can be improved to more than 97 percent.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.