CN113481342B - Method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite through calcium-free low-temperature reduction - Google Patents
Method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite through calcium-free low-temperature reduction Download PDFInfo
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- C22B34/12—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08
- C22B34/1236—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching
- C22B34/124—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors
- C22B34/125—Obtaining titanium or titanium compounds from ores or scrap by metallurgical processing; preparation of titanium compounds from other titanium compounds see C01G23/00 - C01G23/08 obtaining titanium or titanium compounds from ores or scrap by wet processes, e.g. by leaching using acidic solutions or liquors containing a sulfur ion as active agent
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Abstract
The invention discloses a method for preparing iron and separating vanadium and titanium from vanadium titano-magnetite by calcium-free low-temperature reduction, belongs to the technical field of comprehensive utilization of vanadium titano-magnetite, and solves the problem of low vanadium and titanium recovery rate of the existing method for reducing the vanadium titano-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 loaded into a melting and separating electric furnace to melt and separate molten iron and slag from the metallized pellets; refining slag, leaching in dilute sulfuric acid to obtain iron sulfate, aluminium sulfate and V 2 O 5 Dissolving 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
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 using a blast furnace after decades of research, but the grade of 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 reduction coal consumption of one ton of metal iron reaches more than 1000 kilograms, and gas of more than 6GJ is needed for supplement 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 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 a mass ratio of 100:14 to 25: 2-6, preparing materials, 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 ℃;
s4, refining the slag, leaching in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V 2 O 5 Dissolving the titanium-containing slag into the solution, and separating solid from liquid to obtain the titanium-containing slag and TiO in the titanium-containing slag 2 The content is more than 40 percent;
and 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 using NaOH to precipitate iron, adjusting the pH value to be 4.5-5 after solid-liquid separation, precipitating aluminum, performing solid-liquid separation, and 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 30-50 mm.
Further, in the step S1, the moisture 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 60mm.
Further, in the step S3, the mass percentage of FeO in the slag is 5-10%.
Further, in the step S3, the existing steelmaking equipment is used to replace the melting and separating electric furnace, the hot-state metallized pellets are directly added into the existing steelmaking equipment, and the existing steelmaking equipment is used to melt and separate the hot-state metallized pellets.
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, after the metalized pellet is cooled, refining and magnetic separation are performed 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 the steps S4 and S5.
The invention can at least realize one of the following beneficial effects:
(1) The method of the invention 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.
(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 melting 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 of the invention does not add flux CaO, improves the quality of the titanium slag and is convenient for reducing the cost of preparing titanium dioxide subsequently.
(5) In the method of the invention, vanadium is separated from slag and V is prepared 2 O 5 The 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 tunnel kiln includes such steps as pressing sodium carbonate, powdered coal, vanadium-titanium magnetite ore, etc. into balls, loading them in silicon carbide tank, heating to 1150-1250 deg.C in tunnel kiln, reducing, cooling, breaking, ball grinding, hydrolysis to extract vanadium and recovering titanium. 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.
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 a mass ratio of 100:14 to 25: 2-6 of burdening, mixing uniformly, 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 ℃; 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;
s4, leaching slag after refining in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V 2 O 5 Dissolving the titanium-containing slag into the solution, and after solid-liquid separation, the solid is titanium-containing slag, wherein TiO in the titanium-containing slag 2 The content is more than 40%, and the filtrate contains vanadium, iron and aluminum elements;
and 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 using NaOH to precipitate iron, adjusting the pH value to be 4.5-5 after solid-liquid separation, precipitating aluminum, performing solid-liquid separation, and evaporating and crystallizing the residual filtrate to obtain anhydrous sodium sulphate.
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, indirect heating requires the use of heat resistant steel, and the highest grade heat resistant steel at present also withstands 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 the step S1, the vanadium-titanium magnetite powder mainly includes, by mass: siO 2 2 ：0.5％～2.5％，CaO：0.5％～2.0％，MgO：1.5％～3.0％，Al 2 O 3 ：1.0％～5.0％，TiO 2 ：10.0％～20.0％，V 2 O 5 :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 the metallic iron, in step S1, the controlling of the components of the reducing agent mainly includes, in mass percent: 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 meshes, taking the energy consumption of the mill and the reaction efficiency into consideration.
The inventor finds out through long-term intensive research that: at the temperature of 1000-1150 ℃, the carbon-oxygen ratio only needs to be 0.8-0.9 of the integral ratio under the condition of reducing atmosphere, 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; when the carbon-oxygen ratio is 0.8 to 0.9, the amount of the pulverized coal is preferably 14 to 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 to 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 ellipsoid, 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, a low temperature reaction and heat transfer are a limiting link, in order to complete the reduction task quickly, the thickness of the pellets in the indirect heating reduction device in the heating direction is not more than 60mm, and the material thickness is, for example, 20 to 60mm, such as 20mm,25mm,30mm,35mm,40mm,45mm,50mm,55mm and 60mm. Under the conditions of the thickness, the indirect heating, the material temperature of 1000-1150 ℃ and the 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 type heating furnace or a boat pushing furnace. 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 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 melting temperature of the slag, and the more easily the high-melting-point titanium carbide 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, feO in the slag is controlled to be 5-10% in the step S3, 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 the step S3, the melting and separating electric furnace may be heated by a non-contact method, such as microwave melting and separating smelting or medium frequency electric furnace smelting; electrode heating, such as electric arc furnaces, ore-smelting electric furnaces or special melting and separating electric furnaces, may also be used.
Specifically, in the step S3, the hot metallized pellets can also be directly added into existing steel-making equipment such as a converter, and the existing steel-making equipment is used for melting and separating 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 slag 2 Insoluble in dilute acid, so the present invention uses dilute acid leaching. The slag is firstly thinned 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 time 2 O 5 Entering into solution, the mass concentration of dilute sulphuric acid in the leaching process<20 percent (for example, 13 to 18 percent), the temperature is controlled to be between 60 and 90 ℃, and auxiliary strengthening means such as mechanical stirring, air bubbles and the like 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 containsVanadium, iron and aluminum.
Specifically, in the step S5, the pH value of the filtrate is controlled to be 1.5-2.0, ammonium sulfate is added to precipitate vanadium, and the temperature in the vanadium precipitation process is controlled to be 80-90 ℃; after filtering, controlling the pH value to be 2.8-3.2 by NaOH for iron precipitation, and controlling the temperature in the iron precipitation process to be 70-90 ℃; after solid-liquid separation, the PH is adjusted to 4.5, the temperature of the solution is controlled between 70 and 90 ℃, and Al (OH) is added 3 Nucleating agent and flocculating agent precipitated Al (OH) 3 After solid-liquid separation, evaporating and crystallizing to obtain anhydrous sodium sulphate.
Specifically, in step S5, the ammonium metavanadate obtained by precipitating vanadium can be further processed into V 2 O 5 。
Specifically, in the step S3, 80% of vanadium may be directly added into the molten iron in the electric furnace melting process, and at the same time, 20-30 kg of reducing agent is additionally added when 1 ton of vanadium-titanium magnetite is melted, at this time, 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 sufficient separation of iron and slag.
Specifically, the vanadium-containing molten iron can be blown with oxygen to smelt vanadium slag or smelt cast pig iron according to the smelting steel variety requirement.
It should be noted that, in the step S3, the metallized pellets may also be refined and separated by magnetic separation after being cooled to obtain the metal iron powder and the titanium-containing slag, the metal iron powder briquettes are smelted in the converter, and the titanium-containing slag is processed according to the steps S4 and S5.
Compared with the prior art, the method of the invention controls the grain diameter 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 addition amount of the coal powder is small, so that the S content of the final molten iron is 0.1-0.2%, and 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 of the invention does not add flux CaO, improves the quality of the titanium slag and is convenient for reducing the cost of preparing titanium dioxide subsequently.
In the method of the invention, vanadium is separated from slag and V is prepared 2 O 5 The comprehensive recovery rates of iron, vanadium and titanium are 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 has a process flow chart shown in figure 1. The specific details are as follows:
the vanadium-titanium magnetite powder (particle size 50 to 100 mesh) used in this example had the main components 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 the pellet, wherein the pellet is ellipsoid and has 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 TiO 2 The content is more than 43 percent, and the filtrate contains sulfate of vanadium, iron, aluminum and the like.
Filtering the filtrateControlling pH value at 1.5-2.0, controlling temperature at 90 deg.C in the process of precipitating vanadium, adding ammonium sulfate to precipitate vanadium to obtain ammonium metavanadate, filtering with plate frame, precipitating ferric oxide (containing partial ferric hydroxide) at 90 deg.C and pH value controlled at 2.9-3.1 with NaOH, filtering with plate frame, adjusting pH value of filtrate to 4.5 and temperature at 85 deg.C, adding Al (OH) in the process of precipitating aluminum 3 Separating nucleating agent, flocculant and plate frame, evaporating residual filtrate for crystallization to obtain anhydrous sodium sulfate.
After the solid-liquid separation of the plate frame, the ammonium metavanadate is washed by water, calcined, dried and calcined in a roller kiln, the highest temperature in the kiln is 450 ℃, and 99 percent V is obtained 2 O 5 。
TABLE 1 vanadium titano-magnetite as main ingredient/wt%
| T.Fe | SiO 2 | CaO | MgO | Al 2 O 3 | TiO 2 | V 2 O 5 | 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 vanadium-titanium magnetite powder (particle size 50 to 100 mesh) used in this example had the main components 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 the 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-extracted and put into a melting electric furnace, and the pellets are melted and separated into molten iron and slag at 1530 ℃, wherein Si, P, V and S in the molten iron are respectively 0.02%, 0.025%, 1.05% and 0.18%, and slag TiO is 2 The 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 vanadium titano-magnetite powder, reducing agent and binder were added in the same amounts, mixed, pelletized, dried and reduced in the same manner 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 ℃,30 min) 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 example 1-3, the amount of the 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%, thus greatly reducing 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 (6)
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 S1, mixing vanadium-titanium magnetite powder, a carbonaceous reducing agent and a binder according to a mass ratio of 100:14 to 25: 2-6 of burdening, mixing uniformly, 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; an indirect heating mode is adopted, and the combustion flame is not directly contacted with the pellets;
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 ℃;
s4, leaching slag after refining in dilute sulfuric acid, adding an oxidant in the leaching process, and adding ferric sulfate, aluminum sulfate and V 2 O 5 Dissolving the titanium-containing slag into the solution, and separating solid from liquid to obtain the titanium-containing slag and TiO in the titanium-containing slag 2 The content is more than 40 percent;
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;
in the step S1, the carbon-oxygen ratio of the vanadium-titanium magnetite powder to the carbonaceous reducing agent is 0.8-0.9 of the whole ratio;
in the step S2, the thickness of the pellets in the indirect heating reduction device in the heating direction is not more than 60mm;
in the step S3, the mass percent of FeO in the furnace slag is 5-10%, and 85-90% of V enters the furnace slag;
in the step S5, the temperature of the vanadium precipitation process is controlled to be 80-90 ℃;
in the step S5, the temperature in the iron precipitation process is controlled to be 70-90 ℃;
the S content of the final molten iron is 0.1-0.2%.
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 method for separating vanadium titano-magnetite from vanadium titano-magnetite as recited in claim 1, characterized in that in the step S1, the moisture of the dried pellet 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 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 and separate the hot-state metallized pellets.
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 the step S4, the mass concentration of dilute sulfuric acid is less than 20%.
6. The method for separating iron and vanadium-titanium from vanadium-titanium magnetite as claimed in any one of claims 1 to 5, wherein in step S3, the metallized pellet is cooled, 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 step S4 and step S5.
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