阅读说明：本技术 一种利用电解铝碳渣生产钢水沉淀脱氧剂的方法 (Method for producing molten steel precipitation deoxidizer by using electrolytic aluminum carbon slag ) 是由 王强 俞海明 于 2020-01-07 设计创作，主要内容包括：本发明公开了一种利用电解铝碳渣生产钢水沉淀脱氧剂的方法,将电解铝产生的碳渣,利用球磨机,加工成粒度为100目～150目的颗粒；购买脱水沸石,粒度控制在3～5mm,做为造球的骨料应用；沸石成分为：SiO<Sub>2</Sub> 60—70、Al<Sub>2</Sub>O<Sub>3</Sub><15、Fe<Sub>2</Sub>O<Sub>3</Sub><1.5、CaO<5、MgO<2、K<Sub>2</Sub>O<3、Na<Sub>2</Sub>O<1；将以上的碳渣和脱水沸石,按照质量百分比为65：30的比例混合均匀,然后添加5%的MgCl·6H<Sub>2</Sub>O做粘结剂；将以上材料采用干粉压球机压制成30～50mm的球体,然后烘烤脱除结晶水,该脱氧剂球体的各成分质量百分比%为,MgO<5、F>20、SiO<Sub>2</Sub>>15、Na<25、C<20；转炉或者电炉炼钢结束,开始出钢后,待钢包内的钢水量达到3吨左右,开始随钢流加入脱氧合金的同时,加入本产品脱氧剂球体,其余的炼钢工艺不做改变。(The invention discloses a method for producing a molten steel precipitation deoxidizer by using electrolytic aluminum carbon slag, which comprises the following steps of processing the carbon slag generated by electrolytic aluminum into particles with the granularity of 100-150 meshes by using a ball mill; purchasing dehydrated zeolite, controlling the granularity to be 3-5 mm, and applying the dehydrated zeolite as pelletizing aggregate; the zeolite comprises the following components: SiO 2 2 60—70、Al 2 O 3 <15、Fe 2 O 3 <1.5、CaO<5、MgO<2、K 2 O<3、Na 2 O<1; mixing the carbon residue and the dehydrated zeolite according to the mass percentage of 65: 30, then adding 5 percent of MgCl.6H 2 O is used as a binder; pressing the materials into a sphere with the thickness of 30-50 mm by a dry powder ball press, and then baking to remove crystal water, wherein the mass percent of each component of the deoxidizer sphere is MgO<5、F>20、SiO 2 >15、Na<25、C<20; after the converter or electric furnace steel making is finished and the steel tapping is started, when the molten steel amount in the ladle reaches about 3 tons, the deoxidation alloy is added along with the steel flow, and simultaneously, the product is added for removingThe oxygen agent sphere and other steel-making processes are not changed.)

1. A method for producing a molten steel precipitation deoxidizer by using electrolytic aluminum carbon slag is characterized by comprising the following steps:

1) processing carbon slag generated by electrolytic aluminum into particles with the granularity of 100-150 meshes by utilizing a ball mill according to the mechanochemical reaction principle so as to ensure that the particles have good chemical reaction activity;

2) purchasing dehydrated zeolite with the component content meeting the following mass percentage, controlling the granularity to be 3-5 mm, and applying the dehydrated zeolite as aggregate for pelletizing; the zeolite components used therein were: SiO 2₂60—70、Al₂O₃<15、Fe₂O₃<1.5、CaO<5、MgO<2、K₂O<3、Na₂O<1；

3) Mixing the carbon residue and the dehydrated zeolite according to the mass percentage of 65: 30, then adding 5 percent of MgCl.6H₂O is used as a binder;

4) pressing the materials into a sphere with the thickness of 30-50 mm by a dry powder ball press, and then baking to remove crystal water, wherein the mass percent of each component of the deoxidizer sphere is MgO<5、F>20、SiO₂>15、Na<25、C<20；

5) The deoxidizer ball is pulled and transported to a converter or an electric furnace steelmaking production line for standby;

6) after converter or electric furnace steelmaking is finished and tapping is started, when the molten steel amount in a ladle reaches about 3 tons, the deoxidation alloy is added along with the steel flow, and simultaneously the product is added, and the rest steelmaking processes are not changed;

7) the using amount of the product is 1.0-3 kg/ton steel, wherein the using amount of silicon killed steel is 1.5-3 kg/ton steel, the using amount of aluminum killed steel is 2-3 kg/ton steel, and the using amount of silicon aluminum killed steel is 0.8-2 kg/ton steel.

Technical Field

The invention relates to a method for producing a molten steel precipitation deoxidizer by using electrolytic aluminum carbon slag.

Background

In the production process of electrolytic aluminum, the anode carbon block and the cathode carbon lining can be peeled off from the carbon block or the lining under the thermodynamic conditions of electrochemistry and smelting and the action of aluminum liquid erosion, and enter the electrolyte to form carbon slag.

In the process of aluminum electrolysis production, carbon slag can be burnt on the surface of electrolyte, but in the case of excessive generation (in the case of a self-baking tank), the carbon slag needs to be manually and timely fished out of the tank to reduce the adverse effect of the carbon slag on the electrolysis production process, and the main component of the fished carbon slag is cryolite (Na)₃AlF₆) Sodium aluminium fluoride, α -A1₂0₃And carbon; carbon content is about 40%, electrolyte cyanide is about 60%, and the main components of a typical carbon slag are shown in table 1 below:

table 1: composition of typical electrolytic aluminum carbon slag

The components of the carbon slag produced by the electrolytic aluminum plant are not very different, and the components of the carbon slag produced by Xinjiang certain plant are shown in the following table:

the carbon slag is a dangerous waste, and the national dangerous waste catalogue code 321-026-48 is defined as "inflammable skimming produced in the process of smelting by the aluminum pyrometallurgy".

In the review of the literature (1), li hong published a paper entitled "flotation of carbon slag in aluminum electrolysis" in the journal of light metals of 2002, 6 th, and in the abstract of the paper, "carbon slag is harmful waste generated in the aluminum electrolysis production process, and contains a large amount of fluoride salt. Also avoids the pollution to the environment and has obvious economic and social benefits. "is expressed in terms of content; (2) the liang wen qiang is published on the journal of gansu metallurgy in the 4 th stage of 2017, and the treatise is entitled "disposal and recycling scheme of aluminum ash, carbon slag and overhaul slag", and the middle of the abstract is as follows: the wine steel group Dongxing aluminum industry company generates dangerous solid wastes such as aluminum ash, carbon slag, overhaul slag and the like in the electrolytic aluminum production process every year, and the ecological environment is seriously polluted if the dangerous solid wastes are not treated in time. The method comprises the steps of sorting and crushing the dangerous solid wastes generated by electrolytic aluminum, and then utilizing methods such as flotation, chemical reaction and the like to recycle the dangerous solid wastes which can be recycled and to perform harmless treatment on the dangerous solid wastes which cannot be recycled so as to eliminate pollution to the ecological environment. After the method is implemented, certain economic benefits and remarkable social benefits are achieved. "is expressed in terms of content; (3) liuhaixia discloses a paper entitled "research on fluorine-containing waste residue regeneration cryolite process" in journal of inorganic salt industry of 11 th stage in 2013, and the middle part is that reasonable height and cleanliness of electrolyte in an electrolytic cell must be kept in order to ensure normal production in the production process of electrolytic aluminum. In the traditional method, excessive electrolyte is pumped out and carbon blocks floating on the upper part of the electrolyte are salvaged in the electrolytic process, and the objects are condensed to form fluorine-containing waste residues. According to the calculation, 10-12 kg of fluorine-containing waste residue is generated every 1t of aluminum produced, wherein the fluorine-containing waste residue contains more than 30% of cryolite, about 1% of calcium oxide and about 1% of aluminum oxide, and the balance is carbon particles, graphite carbon, aluminum carbide, ferrosilicon oxide and other impurities. In recent years, researches show that after the fluorine-containing waste residues are subjected to physical treatment such as preliminary manual screening, ball milling, flotation and the like, a cryolite crude product can be obtained, but the cryolite crude product still cannot meet the raw material requirement required by electrolytic aluminum due to high impurity content, and quality improvement is urgently needed. "is expressed in terms of the content.

According to the introduction of the documents, no technology for producing the deoxidizer of converter and electric furnace crude steel water by using the electrolytic aluminum carbon slag exists at present.

In order to obtain high reaction efficiency, sufficient oxygen must be supplied to the molten iron, and near the end of smelting, the molten steel is actually in an over-oxidized state, namely the oxygen content in the molten steel is higher than the oxygen content in equilibrium with carbon, manganese and other elements in the steel, namely, in the molten steel in which the impurities of carbon, silicon and phosphorus are removed in the converter and electric furnace steelmaking, certain dissolved oxygen must be remained.

After the converter steel-making and electric furnace steel-making processes are finished, deoxidized alloy or deoxidized material is added in the steel-tapping process, free oxygen or a pumice body in the molten steel is converted into metal oxide, non-metal oxide and gas, and the harm of the free oxygen in the molten steel to steel-making is eliminated. However, if the oxides generated by deoxidation remain in the molten steel, the oxides become inclusions in the steel, and different negative effects are also generated on the steel, so the steelmaking deoxidation process comprises the following two process contents: (1) converting oxygen in the middle of the molten steel into oxides; (2) the vast majority of these oxides are removed from the molten steel.

Review of literature: (1) shuhaiming, a writing of 'external refining technology of converter molten steel' published in 2011 by the publication of metallurgical industry publishers, adopts carbon deoxidation, and the deoxidation product is gas, does not pollute molten steel, has certain advantages, and common carbon-containing deoxidizer is industrial calcium carbide. The content expression that calcium carbide is mainly used as a diffusion deoxidizer in the LF refining process is that calcium carbide slag is easy to generate and causes recarburization to molten steel. (2) In the article entitled "technique for purifying molten steel in a reaction-induced micro heterogeneous phase" published in iron and steel journal of 10 th of 2014 by Wang Xiaofeng, Tang Fuping et al, there are "bubbles with small size can increase the collision probability with inclusions, improve the removal efficiency of the inclusions, and have the existence of fine slag droplets and the slag washing effect"; (3) zhengshu, Ju Miao Yong in 2008, 6 th journal of Steel, published a paper entitled "research on bubble inclusion removal mechanism in argon blowing molten steel refining process", and the paper has "the bubble inclusion removal mechanism is different under large and small gas quantity conditions". Impurities in a small air volume range are mainly removed by the adhesion of a large amount of dispersed small air bubbles; impurities in a large gas flow range are mainly captured and removed through wake flow of large bubbles. "is expressed in terms of the content.

From the above documents, carbon deoxidation is a common use method in steel making process, but a method of deoxidation by electrolytic aluminum carbon slag has not been disclosed in the published documents. Furthermore, it is known from the literature that a large amount of bubbles or liquid phase can be generated during the deoxidation process, and this contributes positively to the removal of inclusions generated during the deoxidation in the steel making deoxidation process.

Disclosure of Invention

The invention aims to provide a method for producing a molten steel precipitation deoxidizer by using electrolytic aluminum carbon slag, which can change waste into valuable and effectively eliminate pollution of the electrolytic aluminum carbon slag.

The invention aims to realize the method for producing the molten steel precipitation deoxidizer by using the electrolytic aluminum carbon slag, and the process comprises the following steps:

1) processing carbon slag generated by electrolytic aluminum into particles with the granularity of 100-150 meshes by utilizing a ball mill according to the mechanochemical reaction principle so as to ensure that the particles have good chemical reaction activity;

2) purchasing dehydrated zeolite with the component content meeting the following mass percentage, controlling the granularity to be 3-5 mm, and applying the dehydrated zeolite as aggregate for pelletizing; the zeolite components used therein were: SiO 2₂60—70、Al₂O₃<15、Fe₂O₃<1.5、CaO<5、MgO<2、K₂O<3、Na₂O<1；

3) Mixing the carbon residue and the dehydrated zeolite according to the mass percentage of 65: 30, then adding 5 percent of MgCl.6H₂O is used as a binder;

4) pressing the materials into a sphere with the thickness of 30-50 mm by a dry powder ball press, and then baking to remove crystal water, wherein the mass percent of each component of the deoxidizer sphere is MgO<5、F>20、SiO₂>15、Na<25、C<20；

5) The deoxidizer ball is pulled and transported to a converter or an electric furnace steelmaking production line for standby;

6) after converter or electric furnace steelmaking is finished and tapping is started, when the molten steel amount in a ladle reaches about 3 tons, the deoxidation alloy is added along with the steel flow, and simultaneously the product is added, and the rest steelmaking processes are not changed;

7) the using amount of the product is 1.0-3 kg/ton steel, wherein the using amount of silicon killed steel is 1.5-3 kg/ton steel, the using amount of aluminum killed steel is 2-3 kg/ton steel, and the using amount of silicon aluminum killed steel is 0.8-2 kg/ton steel.

The inventor researches and utilizes the deoxidizer for producing crude molten steel by taking carbon slag generated in the aluminum electrolysis process as a main raw material and zeolite as an auxiliary raw material of the deoxidizer according to the ion theory of metallurgical reaction, and according to the basic principle of chemical reaction, the sodium oxide is easy to react with an acid substance to generate sodium silicate with low melting point, and then the sodium silicate reacts with CaO to form slag, so that different low melting point compounds are formed. In the "handbook of general chart data for steelmaking" compiled by Chenxiang, the common compounds are: 8CaO & Na₂O·Al₂O₃、3CaO·2Na₂O·5Al₂O₃、2Na₂O·CaO·3SiO₂、Na₂O·3CaO·6SiO₂、Na₂O·2CaO·3SiO₂They all have melting points below 1540 ℃.

Therefore, in the process design of the invention, one of the core innovation points is as follows: according to the sodium salt in the middle of the carbon slag, the sodium salt can react with acidic substances, namely silicon dioxide and aluminum oxide in zeolite, in the middle of the molten steel to form liquid substances with different components, and impurities generated by deoxidation can be adsorbed in the process of floating from the molten steel, so that the molten steel is purified.

The remarkable advantages of the innovative process are that: by using the auxiliary addition of zeolite, the probability that low-melting-point sodium salt in the middle of carbon slag is reduced into metal sodium by carbon under the condition of steelmaking deoxidization and escapes is reduced, short plates with serious dispersion of smoke dust when the carbon slag is used as a deoxidizer are eliminated or weakened, and the advantages of cross innovation among different industries are revealed.

The inventor finds that the carbon slag contains carbon, fluoride and sodium salt. If the carbon slag is directly applied to deoxidation of converter or electric furnace roughing molten steel, the intermediate sodium salt reacts as follows:

2(Na₃AlF₆)+6[O]→3(Na₂O)+(Al₂O₃) +12[F^-]

2(NaF)+[O]→(Na₂O)+2[F^-]

under the process condition of steel making, the carbon in the middle of the carbon slag and the sodium salt can generate the following chemical reaction:

the generated sodium metal is vaporized and escapes from the molten steel, and is secondarily oxidized with oxygen in the middle of furnace gas, and the reaction equation is as follows:

4{Na}+{O₂}=2{Na₂O}

the reaction produces a large amount of dispersed white smoke dust, which affects the steelmaking process environment and limits the application of carbon slag in the steelmaking precipitation deoxidation process.

The inventor proposes the following innovation points according to the research:

1) the carbon slag is used as main material to produce deoxidant, and the graphite carbon is first used as the component for carbon deoxidization. In order to avoid the added carbon, the carbon is dissolved in the middle of molten steel due to the slow diffusion reaction speed, and the carbon is added to the molten steel. The invention is based on: the critical carbon content theory of carbon-oxygen reaction, namely the carbon content is 0.2-0.6%, and the carbon-oxygen reaction depends on the reaction temperature and the content of various components in the middle of molten steel; the carbon content is lower than 0.2%, the carbon-oxygen reaction depends on the metallurgical principle of diffusion speed of carbon to a reaction area, the mechanochemical reaction principle is adopted, carbon slag is ground into powder and is ground to be 100-150 meshes, the reaction activity is improved, zeolite is added to be used as a coupling material of deoxidation reaction, the diffusion of carbon to the reaction area is promoted, and the probability of the carbon deoxidation reaction is improved;

2) based on the general knowledge that fluoride ions can react with silica, a process has been devised which utilizes dehydrated zeolite as a deoxidizer auxiliary material. In the process, fluoride in the middle of the carbon slag is decomposed to generate fluoride ions, and part of the fluoride can react with silicon dioxide in the zeolite to generate gaseous silicon fluoride, and small particle impurities can be adhered to the silicon fluoride and float into the top slag in the process of escaping from the middle of the molten steel to play a role in purifying the molten steel, so that the process is an important innovation point;

3) by utilizing the characteristic that the middle of carbon slag generated in the process of electrolytic aluminum contains low-melting-point sodium salt, SiO between the carbon slag and zeolite after decomposition under the condition of steelmaking is designed₂And Al₂O₃The principle of reaction to generate low-melting-point liquid sodium aluminate and sodium silicate reduces the amount of sodium salt reduced by carbon into metal sodium and the problem of great smoke pollution when carbon slag is used as a deoxidizer, which is the most important innovation point in the invention;

4) the natural zeolite crystal lattice has many holes and channels with uniform size, some holes and channels can account for more than 50% of the volume of the zeolite crystal, and the holes and channels are a porous material after being heated and dehydrated and are aggregates for powder pelletizing; after the carbon residue powder and the dehydrated zeolite particles are mixed, the carbon residue powder is uniformly dispersed in gaps of the dehydrated zeolite, so that the uniformity of product components can be ensured, and the carbon residue powder is also an innovative point of the invention;

5) the deoxidizer produced by the technology is used as the deoxidizer for converter or electric furnace rough smelting molten steel and added into the molten steel, after fluoride is decomposed, fluorine ions rapidly react with silicon dioxide in the middle of zeolite to partially generate silicon fluoride gas, and in the escape process, the molten steel is stirred to promote carbon in the middle of carbon slag to diffuse to a region with higher oxygen concentration in the molten steel, so that the carbon deoxidation reaction is accelerated, and CO/CO generated by deoxidation₂The bubbles can adhere to small-particle inclusions to float upwards from the molten steel, and the molten steel is purified. The process method eliminates or weakens the risk that carbon in the middle of carbon slag is carburized to molten steel in the deoxidation process, and is also a basic innovation point;

6) the metallic aluminum in the carbon slag is reacted with the deoxidation to generate aluminum oxide, and then the aluminum oxide is reacted with sodium salt to generate various low-melting-point liquid substances, and the liquid substances can adsorb impurities to float upwards together in the floating process from the molten steel, thereby playing the deoxidation role of removing deoxidation products from the middle of the molten steel.

7) In the process design of the invention, the control of the adding amount of the silicon dioxide avoids the problem of silicon increase of the molten steel caused by using a siliceous deoxidizing material in the production process of the aluminum killed steel.

The innovative process realizes the maximization of the potential value of various substances in the carbon slag in the deoxidation process.

In summary, the beneficial contributions of the present invention: about 15kg of carbon slag is generated every 1 ton of electrolytic aluminum is generated, the yield of electrolytic aluminum is 3500-4500 ten thousand tons every year at present, 60 ten thousand tons of carbon slag is generated per year at home, and the process of direct resource utilization has no public introduction; the invention can directly utilize the carbon slag as resources, realizes the maximum utilization of value by using elements such as F, Na, C, Al and the like which are beneficial to steelmaking in the carbon slag, solves the problem of smoking in the use process of the carbon slag as a deoxidizer, and has short treatment flow; the deoxidizer produced by the invention can be generally applied to steel-making production of different deoxidation processes. The product can avoid the use of auxiliary deoxidizing materials such as calcium carbide, pre-melted slag and the like which are traditionally used in steelmaking.

Detailed Description

According to the discovery, the method for producing the molten steel precipitation deoxidizer by using the electrolytic aluminum carbon slag, namely the implementation process for producing the converter slagging agent, comprises the following steps:

1) processing carbon slag generated by electrolytic aluminum into particles with the granularity of 100-150 meshes by utilizing a ball mill according to the mechanochemical reaction principle so as to ensure that the particles have good chemical reaction activity;

2) purchasing dehydrated zeolite with the component content meeting the following mass percentage, controlling the granularity to be 3-5 mm, and applying the dehydrated zeolite as aggregate for pelletizing; the zeolite components used therein were: SiO 2₂60—70、Al₂O₃<15、Fe₂O₃<1.5、CaO<5、MgO<2、K₂O<3、Na₂O<1；

3) Mixing the carbon residue and the dehydrated zeolite according to the mass percentage of 65: 30, then adding 5 percent of MgCl.6H₂O is used as a binder;

4) pressing the materials into a sphere with the thickness of 30-50 mm by a dry powder ball press, and then baking to remove crystal water, wherein the operation is a simple process condition and does not need to be repeated, and the deoxidizer sphere contains MgO in percentage by mass<5、F>20、SiO₂>15、Na<25、C<20；

5) The deoxidizer ball is pulled and transported to a converter or an electric furnace steelmaking production line for standby;

6) after converter or electric furnace steelmaking is finished and tapping is started, when the molten steel amount in a ladle reaches about 3 tons, the deoxidation alloy is added along with the steel flow, and simultaneously the product is added, and the rest steelmaking processes are not changed;

7) the using amount of the product is 1.0-3 kg/ton steel, wherein the using amount of silicon killed steel is 1.5-3 kg/ton steel, the using amount of aluminum killed steel is 2-3 kg/ton steel, and the using amount of silicon aluminum killed steel is 0.8-2 kg/ton steel.