CN113481342A

CN113481342A - Method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite through calcium-free low-temperature reduction

Info

Publication number: CN113481342A
Application number: CN202110748063.5A
Authority: CN
Inventors: 郭培民; 孔令兵; 王磊; 林万舟; 周强
Original assignee: China Iron and Steel Research Institute Group; CISRI Sunward Technology Co Ltd
Current assignee: China Iron and Steel Research Institute Group; CISRI Sunward Technology Co Ltd
Priority date: 2021-07-01
Filing date: 2021-07-01
Publication date: 2021-10-08
Anticipated expiration: 2041-07-01
Also published as: CN113481342B

Abstract

The invention discloses a method for preparing iron and separating vanadium and titanium from vanadium-titanium magnetite by calcium-free low-temperature reduction, belongs to the technical field of comprehensive utilization of vanadium-titanium magnetite, and solves the problem of low vanadium-titanium recovery rate of the existing method for reducing the vanadium-titanium magnetite. The method comprises the following steps: uniformly mixing vanadium-titanium magnetite powder, a carbonaceous reducing agent and a binder, performing cold press molding to obtain pellets, drying the pellets, and then putting the dried pellets into an indirect heating reduction device for heating reduction to obtain metallized pellets, wherein the reaction temperature is 1000-1150 ℃, and the reaction time is 20-80 min; the metallized pellets are hot-taken out and put into a melting and separating electric furnace to melt the metallized pelletsCarrying out chemical separation on molten iron and slag; refining slag, leaching in dilute sulfuric acid to obtain iron sulfate, aluminium sulfate and V₂O₅Dissolving the titanium-containing slag into a solution, and after solid-liquid separation, obtaining a solid which is titanium-containing slag; precipitating vanadium, filtering, precipitating iron, separating solid and liquid, precipitating aluminum, separating solid and liquid, and evaporating and crystallizing the residual filtrate to obtain anhydrous sodium sulfate. The method can realize the green and efficient utilization of vanadium, titanium and iron of the vanadium-titanium magnetite with low coal consumption.

Description

Method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite through calcium-free low-temperature reduction

Technical Field

The invention relates to the technical field of comprehensive utilization of resources of vanadium titano-magnetite, in particular to a method for preparing iron and separating vanadium and titanium by calcium-free low-temperature reduction of vanadium titano-magnetite.

Background

The vanadium titano-magnetite is an important mineral resource in China, and can be recycled by a blast furnace after being researched for decades, but the grade of the titanium-containing slag after the vanadium titano-magnetite is treated by the blast furnace is only about 20 percent at present, the titanium-containing slag is not easy to utilize, and in addition, the comprehensive yield of vanadium is only 70 to 80 percent.

The prereduction and electric furnace melting separation mode of the vanadium titano-magnetite is researched from the last century at home and abroad, wherein the prereduction mode comprises a rotary kiln reduction method, a shaft furnace reduction method, a rotary hearth furnace reduction method and the like. The rotary kiln reduction method has the advantages of higher pre-reduction rate, lower productivity and high energy consumption. The shaft furnace reduction method is suitable for the countries with abundant natural gas resources and relatively low price, and the natural gas resources in China are deficient and high in price, so that the shaft furnace reduction method is not suitable for being adopted. The rotary hearth furnace is used for the pre-reduction test of vanadium titano-magnetite in the last 10 years, but pellets with high metallization rate are difficult to obtain under the special atmosphere of the rotary hearth furnace, so that the smelting energy consumption and the cost of the electric furnace are increased, particularly the corrosion to refractory materials of the electric furnace is difficult, the process is difficult to continue, and a plurality of large-scale test devices stop the test. The problem brought by the sodium-reduction method of the tunnel kiln is that the silicon carbide is used for only a few times, the production cost is too high, and in addition, the volatilized alkali also generates extremely strong corrosivity on refractory materials of the tunnel kiln; in addition, the reduction energy consumption of the tunnel kiln is too high, the coal consumption for reducing one ton of metal iron reaches more than 1000 kilograms, and the gas above 6GJ is required for supplementary heating, so that the economic efficiency of the technology is further reduced. This process has been tried in many countries, but has not been produced.

Disclosure of Invention

In view of the above analysis, the present invention provides a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, which can solve at least one of the following technical problems: (1) the energy consumption for reducing the vanadium titano-magnetite by the tunnel kiln is too high; (2) the recovery rate of vanadium and titanium in the current method for reducing the vanadium titano-magnetite is low.

The purpose of the invention is mainly realized by the following technical scheme:

the invention provides a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, which comprises the following steps:

step S1, mixing vanadium-titanium magnetite powder, a carbonaceous reducing agent and a binder according to the mass ratio of 100: 14-25: 2-6, blending, uniformly mixing, performing cold press molding to obtain pellets, and drying the pellets;

step S2, heating reduction: placing the dried pellets into an indirect heating reduction device for heating reduction to obtain metallized pellets, wherein the reaction temperature in the indirect heating reduction device is 1000-1150 ℃, and the reaction time is 20-80 min;

s3, putting the metallized pellets into a melting and separating electric furnace after hot tapping, and melting and separating the metallized pellets into molten iron and slag at 1450-1550 ℃;

step S4, leaching the refined slag in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V₂O₅Dissolving the titanium-containing slag into the solution, and separating solid from liquid to obtain the titanium-containing slag and TiO in the titanium-containing slag₂The content is more than 40 percent;

and step S5, controlling the pH value of the filtrate to be 1.5-2.0, adding ammonium sulfate to precipitate vanadium, filtering, controlling the pH value to be 2.8-3.2 by NaOH to precipitate iron, after solid-liquid separation, adjusting the pH value to be 4.5-5, precipitating aluminum, after solid-liquid separation, evaporating and crystallizing the residual filtrate to obtain anhydrous sodium sulphate.

Further, in the step S1, the pellets are ellipsoids, and the particle size of the pellets is 30 to 50 mm.

Further, in step S1, the moisture content of the dried pellets is controlled to be 2% or less.

Further, in the step S2, the thickness of the pellets in the indirect heating reduction device in the heating direction is not more than 60 mm.

Further, in the step S3, the mass percentage of FeO in the slag is 5% to 10%.

Further, in the step S3, the existing steel making equipment is used to replace the melting separation electric furnace, the hot metallized pellet is directly added into the existing steel making equipment, and the existing steel making equipment is used to melt separate the hot metallized pellet.

Further, in the step S4, the mass concentration of the dilute sulfuric acid is less than 20%.

Further, in the step S5, the temperature of the vanadium precipitation process is controlled to be 80-90 ℃.

Further, in the step S5, the temperature of the iron precipitation process is controlled to be 70-90 ℃.

Further, in the step S3, the metalized pellets are cooled and then refined and separated by magnetic separation to obtain metal iron powder and titanium-containing slag, the metal iron powder briquettes are smelted in a converter, and the titanium-containing slag is processed according to the steps S4 and S5.

The invention can at least realize one of the following beneficial effects:

(1) according to the method, the particle size of the pellets is controlled to be 30-50 mm, the material thickness is controlled to be below 60mm, and the reaction temperature can be controlled to be 1000-1150 ℃; the carbon preparation amount is reduced by an indirect heating reduction mode, the iron coal powder amount per ton is less than 400 kilograms, and the coal powder using amount is greatly reduced.

(2) In the method, the S content of the final molten iron is 0.1-0.2 percent due to less coal powder addition, so that the smelting sulfur load is greatly reduced.

(3) In the method, low-temperature reduction and hot melt separation are adopted, so that the energy consumption of the whole smelting process is reduced, and the carbon emission is about 50 percent of that of the blast furnace smelting process.

(4) The method does not add flux CaO, improves the quality of the titanium slag, and is convenient for reducing the cost of the subsequent preparation of titanium dioxide.

(5) In the method of the invention, vanadium is separated from slag and V is prepared₂O₅The comprehensive yield of iron, vanadium and titanium is respectively more than 97%, 85% and 95%, and the green and efficient utilization of vanadium, titanium and iron of the vanadium-titanium magnetite is realized with low coal consumption.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and drawings.

Drawings

The drawings are only for purposes of illustrating particular embodiments and are not to be construed as limiting the invention, wherein like reference numerals are used to designate like parts throughout.

FIG. 1 is a process flow diagram of example 1;

FIG. 2 is a process flow diagram of example 2;

FIG. 3 is a process flow diagram of example 3.

Detailed Description

The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form a part hereof, and which together with the embodiments of the invention serve to explain the principles of the invention.

At present, the vanadium titano-magnetite is mostly treated by a blast furnace, but the grade of the titanium-containing slag after the vanadium titano-magnetite is treated by the blast furnace is only about 20 percent, the titanium-containing slag is not easy to be utilized, and in addition, the comprehensive yield of vanadium is only 70 to 80 percent.

The prereduction and electric furnace melting separation mode of the vanadium titano-magnetite is researched from the last century at home and abroad, wherein the prereduction mode comprises a rotary kiln reduction method, a shaft furnace reduction method, a rotary hearth furnace reduction method and the like. The inventor finds that: the rotary kiln reduction method has the advantages of higher pre-reduction rate, lower productivity and high energy consumption. The shaft furnace reduction method is suitable for the countries with abundant natural gas resources and relatively low price, and the natural gas resources in China are deficient and high in price, so that the shaft furnace reduction method is not suitable for being adopted. The pellets with high metallization rate are difficult to obtain in the special atmosphere of the rotary hearth furnace, so that the smelting energy consumption and the smelting cost of the electric furnace are increased, particularly, the process is difficult to continuously carry out on the erosion of refractory materials of the electric furnace, and a plurality of large-scale test devices stop the test. A sodium salt reduction method for a tunnel kiln comprises the steps of pressing balls of sodium carbonate, coal powder, vanadium-titanium magnetite and the like, adding the pressed balls into a silicon carbide tank, heating the silicon carbide tank to 1150-1250 ℃ in the tunnel kiln for reduction, cooling, crushing, ball milling, hydrolyzing for vanadium extraction and titanium recovery. The method has the advantages that the grade of the titanium slag is obviously improved compared with that of the high furnace method, the vanadium has a certain recovery rate, and the iron, vanadium and titanium are primarily recycled. However, since sodium carbonate has a low melting point, is easy to volatilize, and has strong corrosivity, the method has the problems that the silicon carbide is used for only a few times, the production cost is too high, in addition, the volatilized alkali also generates strong corrosivity on the refractory material of the tunnel kiln, and the service life of the refractory material of the tunnel kiln is reduced; in addition, the reduction energy consumption of the tunnel kiln is too high, the reduction coal consumption of one ton of metal iron products reaches more than 1000 kilograms, and the gas of more than 6GJ is needed for supplementary heating, so that the economy is poor.

s3, putting the metallized pellets into a melting and separating electric furnace after hot tapping, and melting and separating the metallized pellets into molten iron and slag at 1450-1550 ℃; wherein Si and P in the molten iron are less than 0.03 percent, V is less than 0.1 percent, and oxides of vanadium, titanium, silicon, aluminum, calcium, magnesium and a small amount of iron enter the slag;

step S4, leaching the refined slag in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V₂O₅Dissolving the titanium-containing slag into the solution, and separating solid from liquid to obtain the titanium-containing slag and TiO in the titanium-containing slag₂The content is more than 40%, and the filtrate contains vanadium, iron and aluminum elements;

It should be noted that, the inventors have found through long-term intensive studies that: the carbothermic reduction temperature of the vanadium titano-magnetite is normally higher than 1250 ℃, such as rotary hearth furnace reduction. The rotary hearth furnace belongs to a flame direct heating mode, the pellet is heated by heat generated by flame combustion, but the weak oxidizing atmosphere influences the preparation of the high-metallization pellet, the carbon-oxygen ratio of the normal reduction ingredient is according to the integral ratio, but even if the carbon-oxygen ratio reaches 1.2 times of the integral ratio, the metallization rate of the pellet is only 60%, in order to reach the metallization rate of more than 80%, the carbon-oxygen ratio reaches 1.6 times of the integral ratio, the carbon consumption is seriously increased, the content of S in subsequent molten iron reaches more than 0.5% due to the great increase of the coal usage amount, and the desulfurization cost of steel making is increased. In order to change the direct heating mode, the invention adopts an indirect heating mode, namely, the combustion flame is not directly contacted with the pellets, so as to improve the reduction rate of the metallic iron and reduce the carbon consumption. However, the indirect heating needs to use heat-resistant steel, and the highest-grade heat-resistant steel at present can bear 1200-1250 ℃. Therefore, the invention provides a method for properly controlling the size of the raw material pellets from the manufacturing economy of equipment so as to ensure the high reduction rate of the pellets at 1000-1150 ℃, reduce the reaction temperature and adapt to an indirect heating device.

Specifically, in step S1, the vanadium-titanium magnetite powder mainly includes, by mass: SiO 2₂：0.5％～2.5％，CaO：0.5％～2.0％，MgO：1.5％～3.0％，Al₂O₃：1.0％～5.0％，TiO₂：10.0％～20.0％，V₂O₅: 0.1% -2.0%, S: 0.1% -1.0%, wherein, T.Fe: 40 to 60 percent.

Specifically, in step S1, the carbonaceous reducing agent may be pulverized coal, and the quality of the titanium slag is related to the components of the vanadium-titanium magnetite powder and the components of the added reducing agent, so in order to improve the quality of the reduced titanium slag and metallic iron, in step S1, the component of the reducing agent is controlled to mainly include, by mass: fixing carbon: more than 60%, less than 25% of volatile components and less than 10% of ash content.

Specifically, in the step S1, the particle size of the vanadium-titanium magnetite powder is controlled to be 50 to 100 mesh by comprehensively considering the energy consumption of the mill and the reaction efficiency.

The inventor finds that: at 1000-1150 ℃, the carbon-oxygen ratio only needs to be 0.8-0.9 of the whole ratio under the reducing atmosphere condition, and in consideration of the fluctuation of the components of the vanadium titano-magnetite and the reducing agent coal powder, in the step S1, the mass ratio of the vanadium titano-magnetite to the reducing agent coal powder is controlled to be 100: 14 to 25. Assuming that the vanadium titano-magnetite is 100g, wherein the total iron content is 40-60 g, the oxygen content in the corresponding iron oxide is 15-23 g, assuming that the carbon reduction product is CO, the carbon mass is 11-17 g under the condition of total reduction, and the coal powder converted into 65% fixed carbon is 17-26 g; under the condition that the carbon-oxygen ratio is 0.8-0.9, the actual amount of the coal powder is 14-23 g.

Specifically, in the step S1, a binder is required to be used in the cold press molding process, in order to reduce the content of gangue mixed into the pellets, an organic binder is preferred, and the mass ratio of the binder to the vanadium titano-magnetite is 2-6: 100.

specifically, in the step S1, the size of the pellets is too large, the heat transfer of the pellets is poor, and the reaction is slow; the pellet size is small, and the overall economy is low; therefore, the pellets are controlled to be ellipsoids, and the particle size of the pellets is 30-50 mm.

Specifically, in step S1, the moisture content of the dried pellets is controlled to be 2% or less in order to reduce the bursting of the pellets.

Specifically, in the step S2, since the carbothermic reduction reaction is a strong endothermic reaction, the low-temperature reaction and the heat transfer are restrictive links, in order to complete the reduction task quickly, the thickness of the heated direction of the pellets in the indirect heating reduction device is not more than 60mm, and illustratively, the thickness of the material is 20 to 60mm, such as 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, and 60 mm. Under the conditions of the thickness, indirect heating, material temperature of 1000-1150 ℃ and reaction time of 20-80 min, the reduction rate of the iron is more than 85 percent.

Specifically, in step S2, the indirect heating and reducing device may be a steel belt heating furnace, a pusher furnace, or the like. Because the steel boat of the boat pushing furnace has large mass and the heating energy consumption is increased, the indirect heating reduction device of the invention is preferably a steel belt type heating furnace.

Specifically, in step S2, the indirect heating and reducing device may be heated by fuel gas, resistance wire, or microwave.

Specifically, in step S3, the lower the FeO in the slag of the melting electric furnace, the higher the ratio of V into the molten iron, but the higher the slag melting temperature, and the more easily titanium carbide having a high melting point is formed, making the operation difficult. FeO in the slag is increased, the proportion of vanadium entering the slag is high, and the slag temperature is reduced due to the action of FeO, so that the operation is convenient; and FeO can also replace CaO to play a certain role in desulfurization. In order to control the distribution of V and reduce the content of V in the molten iron, in the step S3, FeO in the slag is controlled to be 5-10%, so that 85-90% of V enters the slag; meanwhile, the coal powder is less in addition, so that the S content of the final molten iron is 0.1-0.2%, which is equivalent to that of blast furnace smelting (CaO added for slagging). By controlling the FeO content in the slag, the usage amount of the coal dust is reduced, the raw material cost is reduced, the S content in the molten iron can be reduced, and the quality of the molten iron is improved.

Specifically, in the step S3, the metallized pellets are melted in the melting and separating electric furnace in a hot state, so that energy consumption can be reduced to the greatest extent, and the pellets are melted and separated into molten iron and slag at 1400 to 1500 ℃ according to slag components. Because of the oxidizing atmosphere of the slag, Si and P in the molten iron are less than 0.03 percent, and V is less than 0.1 percent, and the molten iron enters a subsequent molten iron pretreatment link for further desulfurization.

Specifically, in step S3, the melting and separating electric furnace may be heated by non-contact type, such as microwave melting and separating smelting or medium frequency electric furnace smelting; electrode heating, such as an electric arc furnace, a submerged arc furnace, or a special melting furnace, may also be used.

Specifically, in step S3, the hot metallized pellets may be directly added to existing steel making equipment such as a converter, and the existing steel making equipment is used to melt and separate the hot metallized pellets, so that a new melting and separating electric furnace is not needed.

Specifically, in the step S4, TiO is added according to the nature of the slag₂Insoluble in dilute acid, so the present invention uses dilute acid leaching. The slag is refined to 100-200 meshes before leaching. In order to facilitate leaching, ferrous iron and trivalent vanadium in the slag need to be oxidized into high valence, and subsequent separation is facilitated, so oxidants such as hydrogen peroxide or sodium hypochlorite need to be added in the leaching process of dilute sulfuric acid, ferric sulfate and aluminum sulfate need to be dissolved, and V is added at the same time₂O₅Entering into solution, the mass concentration of dilute sulphuric acid in the leaching process<20% (for example, 13% -18%), the temperature is controlled at 60-90 ℃, and auxiliary strengthening means such as mechanical stirring and air bubbles are needed; heating methods such as steam heating or microwave heating can be adopted. After solid-liquid separation, the solid is titanium-containing slag, and the filtrate contains vanadium, iron and aluminum elements.

Specifically, in the step S5, the pH value of the filtrate is controlled to be 1.5 to 2.0, ammonium sulfate is added to precipitate vanadium, and the temperature in the vanadium precipitation process is controlled to be 80 to 90 ℃; after filtering, controlling the pH value to be 2.8-3.2 by NaOH to precipitate iron, and controlling the temperature in the iron precipitation process to be 70-90 ℃; after solid-liquid separation, adjusting the pH value to 4.5, controlling the temperature of the solution at 70-90 ℃, and adding Al (OH)₃Nucleating and flocculating agents precipitating Al (OH)₃After solid-liquid separation, evaporating and crystallizing to obtain anhydrous sodium sulphate.

Specifically, in step S5, the ammonium metavanadate obtained by vanadium precipitation can be further processed into V₂O₅。

Specifically, in the step S3, 80% of vanadium can be directly added into the molten iron in the electric furnace melting process, and simultaneously titanium is added into the slag, at this time, 20-30 kg of reducing agent needs to be additionally added when 1 ton of vanadium-titanium magnetite is melted, FeO in the slag is reduced to less than 2%, the melting point of the slag becomes high, and the melting temperature of the melting electric furnace is higher than 1500 ℃ to ensure that the slag and iron are fully separated.

Specifically, the vanadium-containing molten iron can be used for smelting vanadium slag by oxygen blowing or smelting and casting pig iron according to the requirements of smelting steel seeds.

In step S3, the metallized pellet may be cooled, refined, and separated by magnetic separation to obtain metal iron powder and titanium-containing slag, the metal iron powder briquette enters a converter for smelting, and the titanium-containing slag is processed according to steps S4 and S5.

Compared with the prior art, the method controls the particle size of the pellets to be 30-50 mm and the material thickness to be below 60mm, and can control the reaction temperature to be 1000-1150 ℃; the carbon preparation amount is reduced by an indirect heating reduction mode, the iron coal powder amount per ton is less than 400 kilograms, and the coal powder using amount is greatly reduced.

In the method, the S content of the final molten iron is 0.1-0.2 percent due to less coal powder addition, so that the smelting sulfur load is greatly reduced.

In the method, low-temperature reduction and hot melt separation are adopted, so that the energy consumption of the whole smelting process is reduced, and the carbon emission is about 50 percent of that of the blast furnace smelting process.

The method does not add flux CaO, improves the quality of the titanium slag, and is convenient for reducing the cost of the subsequent preparation of titanium dioxide.

In the method of the invention, vanadium is separated from slag and V is prepared₂O₅The comprehensive yield of iron, vanadium and titanium is respectively more than 97%, 85% and 95%, and the green and efficient utilization of vanadium, titanium and iron of the vanadium-titanium magnetite is realized.

Example 1

The embodiment provides a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, which adopts the method and adopts a process flow chart shown in figure 1. The specific details are as follows:

the main components of the vanadium-titanium magnetite powder (particle size 50-100 mesh) used in this example are shown in table 1. The reducing agent is pulverized coal as shown in Table 2, and the binder is organic binder such as waste molasses.

The vanadium-titanium magnetite powder, the coal powder and the binder are mixed according to the mass ratio of 100: 20: 3, preparing materials, uniformly mixing, and performing cold press molding to obtain pellets, wherein the pellets are ellipsoid and have the particle size of 30-50 mm. Drying on a continuous dryer, wherein the temperature of drying air inlet is 300 ℃, the drying air inlet stays for 30min, and the moisture of the pellets is 1.8%.

The pellets enter an indirect heating reduction device for reduction, the spreading thickness is 50mm, the maximum temperature of the materials is 1100 ℃, the reaction time is 30min, and the pellet metallization rate is 92%.

The metallized pellets are hot-taken out and put into a melting electric furnace, the pellets are melted at 1480 ℃ to separate molten iron and slag, Si, P, V and S in the molten iron are respectively 0.006%, 0.008%, 0.05% and 0.18%, and oxides of vanadium, titanium, silicon, aluminum, calcium, magnesium, a small amount of iron and the like enter the slag.

Refining the slag after water quenching until the slag passes through a 100-mesh sieve, leaching in dilute sulfuric acid with the mass concentration of 15%, controlling the leaching temperature at 75 ℃, adopting auxiliary strengthening means such as mechanical stirring, air bubbles and the like to perform the leaching process, wherein the stirring speed is 50 r/min, adding hydrogen peroxide in the leaching process, and leaching for 3 hours. Solid-liquid separation is carried out by adopting a plate frame, and the solid is titanium-containing slag and TiO₂The content is more than 43 percent, and the filtrate contains sulfate of vanadium, iron, aluminum and the like.

Controlling the pH value of the filtrate at 1.5-2.0, controlling the temperature in the vanadium precipitation process at 90 ℃, adding ammonium sulfate to precipitate vanadium to obtain ammonium metavanadate, filtering by using a plate frame, controlling the pH value to 2.9-3.1 by using NaOH, precipitating iron oxide (containing part of ferric hydroxide) at 90 ℃, filtering by using a plate frame, adjusting the pH value of the filtrate to 4.5 and the temperature to 85 ℃, and adding Al (OH) in the aluminum precipitation process₃Separating nucleating agent and flocculant with plate frame, evaporating residual filtrate and crystallizing to obtain anhydrous sodium sulfate.

Washing ammonium metavanadate obtained after solid-liquid separation of a plate frame, calcining, drying and calcining in a roller kiln, wherein the highest temperature in the kiln is 450 ℃, and 99% V is obtained₂O₅。

TABLE 1 vanadium titano-magnetite main ingredient/wt.%

T.Fe	SiO₂	CaO	MgO	Al₂O₃	TiO₂	V₂O₅	S
								58.12	2.37	1.2	2.58	3.51	10.6	0.735	0.35

TABLE 2 main constituents of coal dust

Fixed carbon	Volatile matter	Ash content	S
				79.29％	8.28％	12.50％	0.45％

Example 2

The embodiment provides a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, which adopts the method and adopts a process flow chart shown in figure 2. The specific details are as follows:

the main components of the vanadium-titanium magnetite powder (particle size 50-100 mesh) used in this example are shown in table 1. The reducing agent is pulverized coal as shown in Table 2, and the binder is an organic binder such as sodium carboxymethylcellulose.

The vanadium titano-magnetite fine powder, the carbonaceous reducing agent and the binder are mixed according to the mass ratio of 100: 22: 3, preparing materials, uniformly mixing, and performing cold press molding to obtain pellets, wherein the pellets are ellipsoid and have the particle size of 30-50 mm. Drying on a continuous dryer, wherein the temperature of drying air inlet is 300 ℃, the drying air inlet stays for 30min, and the moisture of the pellets is 1.8%.

The pellets enter an indirect heating reduction device for reduction, the spreading thickness is 47mm, the maximum temperature of the materials is 1100 ℃, the reaction time is 30min, and the pellet metallization rate is 93%.

The metallized pellets are hot-taken out and put into a melting and separating electric furnace, the pellets are melted and separated into molten iron and slag at 1530 ℃, the Si, P, V and S in the molten iron are respectively 0.02%, 0.025%, 1.05% and 0.18%, and the slag TiO is₂The content is 41 percent.

Example 3

The embodiment provides a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, which adopts the method and adopts a process flow chart shown in figure 3. The specific details are as follows:

the addition amounts of vanadium-titanium magnetite powder, reducing agent and binder, mixing, pelletizing, drying and reduction were the same as in example 1.

The metallized pellets obtained after the pellet reduction are refined to be 100 meshes after being cooled, and slag and iron are separated by a magnetic separator.

The obtained iron powder is dehydrated by indirect drying (300 ℃, 30min) to control the moisture below 3 percent to obtain metallic iron powder with the total iron content of 93 percent and the V content of 0.25 percent, the metallic iron powder is cold-pressed into direct reduction iron blocks, and the direct reduction iron blocks are added into a converter, an electric furnace or a blast furnace.

And extracting vanadium from the vanadium-and titanium-containing slag according to the slag leaching method in the embodiment 1 to obtain the titanium-containing slag.

In the above examples 1-3, the amount of coal powder for treating 1 ton of vanadium titano-magnetite is 150-250 kg, which is much lower than the existing 1000 kg, and no CaO is needed, and the S content of the final molten iron is 0.1-0.2%, which greatly reduces the smelting sulfur load; therefore, the method disclosed by the invention is low in coal consumption, low in power consumption and low in carbon emission, and can be used for producing high-quality high-titanium slag powder and metal iron powder, so that the green high-added-value utilization of the vanadium-titanium magnetite is realized, and the economic benefit is obvious.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.

Claims

1. A method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction is characterized by comprising the following steps:

step S4, leaching the refined slag in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V₂O₅Dissolving into solution and solidifyingAfter liquid separation, the solid is titanium-containing slag, and TiO in the titanium-containing slag₂The content is more than 40 percent;

2. The separation method for preparing iron and vanadium-titanium from vanadium-titanium magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S1, the pellets are ellipsoid pellets, and the particle size of the pellets is 30-50 mm.

3. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S1, the moisture content of the dried pellets is controlled below 2%.

4. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S2, the thickness of the pellets in the indirect heating reduction device in the heating direction is not more than 60 mm.

5. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, characterized in that in step S3, the mass percentage of FeO in the slag is 5% -10%.

6. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S3, the existing steel-making equipment is used to replace a melting electric furnace, the hot-state metallized pellets are directly added into the existing steel-making equipment, and the existing steel-making equipment is used to melt the hot-state metallized pellets.

7. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, characterized in that in step S4, the mass concentration of dilute sulfuric acid is less than 20%.

8. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S5, the temperature of the vanadium precipitation process is controlled to be 80-90 ℃.

9. The separation method for preparing iron and vanadium-titanium from vanadium titano-magnetite by calcium-free low-temperature reduction according to claim 1, wherein in the step S5, the temperature of the iron precipitation process is controlled to be 70-90 ℃.

10. The separation method for preparing iron and vanadium-titanium from vanadium-titanium magnetite by calcium-free low-temperature reduction according to claims 1 to 9, wherein in the step S3, the metalized pellet is cooled and then refined and separated by magnetic separation to obtain metal iron powder and titanium-containing slag, the metal iron powder briquette is smelted in a converter, and the titanium-containing slag is processed according to the steps S4 and S5.