阅读说明：本技术 钒钛磁铁矿低温还原焙烧实现铁、钒、钛综合利用的方法 (Method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite ) 是由 郭培民 孔令兵 王磊 林万舟 周强 于 2021-06-28 设计创作，主要内容包括：本发明公开了钒钛磁铁矿低温还原焙烧实现铁、钒、钛综合利用的方法,属于钒钛磁铁矿的资源利用领域,解决了现有钒钛磁铁矿还原过程造成的强腐蚀,能耗高问题。包括将钒钛磁铁矿精粉、碳质还原剂、钠化剂、粘结剂混匀、成型得到球团、干燥；球团进行低温钠化还原,还原装置采用物料上方和下方均可加热的间接加热装置；还原后的金属化球团细化到100目以细进行水解,水解后分离得到渣铁混合物和第一滤液；渣铁混合物磁选分离得到炉渣和金属铁粉；第一滤液一次碳分,过滤分离得到SiO-2、Al-2O-3沉淀和第二滤液；第二滤液二次碳分,过滤分离得到偏钒酸铵沉淀和第三滤液；第三滤液三次碳分。本发明的方法可低煤耗实现钒、钛、铁的绿色高附加值利用。(The invention discloses a method for realizing comprehensive utilization of iron, vanadium and titanium by reducing and roasting vanadium-titanium magnetite at low temperature, belongs to the field of resource utilization of vanadium-titanium magnetite, and solves the problems of strong corrosion and high energy consumption caused by the reduction process of the existing vanadium-titanium magnetiteAnd (5) problems are solved. Comprises mixing vanadium titano-magnetite fine powder, carbonaceous reducing agent, sodiumizing agent and binder, molding to obtain pellets, and drying; carrying out low-temperature sodium treatment reduction on the pellets, wherein the reduction device adopts an indirect heating device which can heat the materials above and below; refining the reduced metallized pellets to 100 meshes for hydrolysis, and separating to obtain a slag iron mixture and a first filtrate; magnetically separating the slag-iron mixture to obtain slag and metal iron powder; performing primary carbonation on the first filtrate, and filtering and separating to obtain SiO 2 、Al 2 O 3 Precipitating and filtering the solution to obtain a second filtrate; performing secondary carbonation on the second filtrate, and filtering and separating to obtain an ammonium metavanadate precipitate and a third filtrate; and carrying out carbon decomposition on the third filtrate for three times. The method can realize the green high-added-value utilization of vanadium, titanium and iron with low coal consumption.)

1. A method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite is characterized by comprising the following steps:

step S1, mixing, uniformly mixing and molding the vanadium titano-magnetite fine powder, the carbonaceous reducing agent, the sodiumizing agent and the binder according to the mass ratio to obtain pellets, and drying the pellets;

s2, allowing the dried pellets to enter a reduction device for sodium salt reduction, wherein the highest temperature in the furnace is 850-950 ℃, and the reaction time is 60-240 min; wherein, the reduction device adopts an indirect heating device which can heat the upper part and the lower part of the material;

s3, cooling the reduced metallized pellets, crushing, ball-milling to 100 meshes to carry out hydrolysis, controlling the pH value to be more than 12, and separating to obtain a slag iron mixture and a first filtrate;

step S4, carrying out magnetic separation on the slag-iron mixture to obtain slag and metal iron powder; then drying the metal iron powder to obtain primary metal iron powder with more than 95% of total iron, wherein the slag after magnetic separation is titanium-containing slag;

step S5, carrying out primary carbonation on the first filtrate, adjusting the pH value to 9-10, and filtering and separating to obtain SiO₂、Al₂O₃Precipitating and filtering the solution to obtain a second filtrate;

step S6, carrying out secondary carbonation on the second filtrate, adjusting the pH value to 8.5-9, adding ammonium sulfate or ammonium chloride to precipitate vanadium, and adding an oxidant in the vanadium precipitation process to promote the formation of ammonium metavanadate precipitate; filtering and separating to obtain ammonium metavanadate precipitate and a third filtrate;

and step S7, performing carbonization for three times on the third filtrate, adjusting the pH value to 8.3-8.5 to form a sodium bicarbonate solution, evaporating and crystallizing to obtain a sodium bicarbonate solid, and drying or calcining the sodium bicarbonate solid to be used as a sodium treatment agent.

2. The method of claim 1, wherein in step S1, the sodium treatment agent comprises at least one of sodium carbonate or sodium bicarbonate.

3. The method of claim 1, wherein in the step S1, the mass ratio of the vanadium titano-magnetite fine powder, the sodium agent, the carbonaceous reducing agent and the binder is 100: 25-55: 15-25: 2 to 8.

4. The method as claimed in claim 1, wherein the pellet prepared in the step S1 has a particle size of 30-50 mm.

5. The method of claim 1, wherein in step S2, the thickness of the material is not more than 80 mm.

6. The method as claimed in claim 1, wherein in step S3, the first filtrate includes NaVO₂、Na₂SiO₃、NaAlO₂And NaOH.

7. The method of claim 1, wherein in the step S4, the primary metallic iron powder can be continuously reduced by hydrogen to obtain a secondary metallic iron powder with total iron exceeding 97%.

8. The method as claimed in claim 1, wherein the step S5 is implemented by introducing CO into the first filtrate for carbon separation₂Gas to adjust pH, CO₂The air source is CO containing residual heat generated in the pellet reduction process in the step S2₂A gas.

9. The method according to any one of claims 1 to 8, wherein in step S6, the ammonium metavanadate is washed with water, dried and calcined to V₂O₅。

10. The method according to claim 9, wherein in the step S6, the calcining temperature is 450-600 ℃.

Technical Field

The invention relates to the technical field of comprehensive utilization of resources of vanadium titano-magnetite, in particular to a method for realizing comprehensive utilization of iron, vanadium and titanium by reducing and roasting the vanadium titano-magnetite at a low temperature.

Background

The vanadium titano-magnetite is an important mineral resource in China, and can be recycled by a blast furnace after decades of researches, but the grade of titanium-containing slag in the blast furnace is only about 20 percent, the titanium-containing slag is not well utilized, and in addition, the comprehensive yield of vanadium is only 70 to 80 percent.

A non-blast furnace sodium salt reduction method is tried in China, and is typically implemented by reducing in a tunnel kiln, 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 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 easily volatilized 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, and in addition, the volatilized alkali also has strong corrosivity on refractory materials of a 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 aims to provide a method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite, which can solve at least one of the following technical problems: (1) the problem of strong corrosion caused by the alkali reduction roasting process of the vanadium titano-magnetite; (2) the energy consumption of the vanadium titano-magnetite alkali reduction roasting process is too high.

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

the invention provides a method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite, which comprises the following steps:

step S1, mixing, uniformly mixing and molding the vanadium titano-magnetite fine powder, the carbonaceous reducing agent, the sodiumizing agent and the binder according to the mass ratio to obtain pellets, and drying the pellets;

s2, allowing the dried pellets to enter a reduction device for sodium salt reduction, wherein the highest temperature in the furnace is 850-950 ℃, and the reaction time is 60-240 min; wherein, the reduction device adopts an indirect heating device which can heat the upper part and the lower part of the material;

s3, cooling the reduced metallized pellets, crushing, ball-milling to 100 meshes to carry out hydrolysis, controlling the pH value to be more than 12, and separating to obtain a slag iron mixture and a first filtrate;

step S4, carrying out magnetic separation on the slag-iron mixture to obtain slag and metal iron powder; then drying the metal iron powder to obtain primary metal iron powder with more than 95% of total iron, wherein the slag after magnetic separation is titanium-containing slag;

step S5, carrying out primary carbonation on the first filtrate, adjusting the pH value to 9-10, and filtering and separating to obtain SiO₂、Al₂O₃Precipitating and filtering the solution to obtain a second filtrate;

step S6, carrying out secondary carbonation on the second filtrate, adjusting the pH value to 8.5-9, adding ammonium sulfate or ammonium chloride to precipitate vanadium, and adding an oxidant in the vanadium precipitation process to promote the formation of ammonium metavanadate precipitate; filtering and separating to obtain ammonium metavanadate precipitate and a third filtrate;

and step S7, performing carbonization for three times on the third filtrate, adjusting the pH value to 8.3-8.5 to form a sodium bicarbonate solution, evaporating and crystallizing to obtain a sodium bicarbonate solid, and drying or calcining the sodium bicarbonate solid to be used as a sodium treatment agent.

Further, in step S1, the sodium treatment agent at least includes one of sodium carbonate or sodium bicarbonate.

Further, in the step S1, the mass ratio of the vanadium titano-magnetite fine powder, the sodium agent, the carbonaceous reducing agent and the binder is 100: 25-55: 15-25: 2 to 8.

Further, in the step S1, the particle size of the prepared pellet is 30 to 50 mm.

Further, in the step S2, the thickness of the material is not more than 80 mm.

Further, in the step S3, the first filtrate includes NaVO₂、Na₂SiO₃、NaAlO₂And NaOH.

Further, in step S4, the primary metallic iron powder can be continuously reduced by hydrogen to obtain a secondary metallic iron powder with total iron exceeding 97%.

Further, in the step S5, the first filtrate is subjected to carbon separation by introducing CO₂Gas to adjust pH, CO₂The air source is CO containing residual heat generated in the pellet reduction process in the step S2₂A gas.

Further, in step S6, the ammonium metavanadate is washed with water, dried, and then calcined to V₂O₅。

Further, in the step S6, the calcination temperature is 450 to 600 ℃.

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

(1) according to the method, the granularity of the pellets is controlled to be 30-50 mm, the indirect heating devices which can be heated above and below the materials are combined for heating reduction, the thickness of the materials is controlled to be below 80mm, the reaction temperature of the vanadium-titanium magnetite can be reduced to 850-950 ℃, the reaction time is 60-240 min, the reduction rate of iron in the vanadium-titanium magnetite can be ensured to exceed 95%, and the requirement of mass production can be met.

(2) The method reduces the sodium reduction roasting temperature of the vanadium titano-magnetite, obviously weakens the corrosivity and volatilization of alkali when the temperature in the furnace is 850-950 ℃, greatly reduces the corrosivity to equipment, and is beneficial to the long-term operation of production.

(3) The method adopts an indirect heating device (i.e. combustion flame is not directly contacted with the material) which can be heated above and below the material to carry out heating reduction; compared with the device adopting internal combustion heating, the device adopting internal combustion heating has large coal consumption required for reaching the same reduction rate due to the weak oxidizing atmosphere of combustion, and the invention adopts an indirect heating mode for reduction, thereby ensuring the reducing atmosphere in the furnace, ensuring that reduced particles can not be subjected to secondary oxidation in the furnace and requiring less reducing agent; the reaction temperature of the method is low, so the required amount of the iron-coal powder per ton is lower than 400 kg, and is far lower than 1000 kg of coal consumption reduced by a tunnel kiln; greatly saves energy and reduces carbon emission.

(4) In the method, the addition amount of the coal powder is small, so that the S content in the final iron powder is 0.1-0.2%, and the smelting sulfur load of the subsequent process is greatly reduced.

(5) The method of the invention produces CO-containing gas by heating reduction₂The waste heat flue gas is used as a raw material for regulating the pH value of the solution, so that the pH value regulating cost is greatly reduced, the waste water evaporation capacity of the system is greatly reduced, the evaporation and crystallization cost is greatly reduced, and in addition, the recycling of sodium salt in the system is promoted.

(6) The method can produce high-quality metal iron powder or high-grade sponge iron and high-quality metal iron V with low cost and low carbon emission₂O₅And the titanium-containing slag, so that the green high-added-value utilization of vanadium, titanium and iron of the vanadium-titanium magnetite is realized.

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 the method of the present invention.

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.

At present, a non-blast furnace sodium reduction method is also available, and is typically a tunnel kiln sodium reduction method, wherein sodium carbonate, coal powder, vanadium titano-magnetite and the like are pressed into balls and then added into a silicon carbide tank, the balls are heated to 1150-1250 ℃ in a tunnel kiln (the tunnel kiln is used for placing materials in the silicon carbide tank with the diameter of 400-500 mm for heating, the reduction heat transfer is slow, the reduction rate can be improved only by improving the reduction temperature and increasing the reduction time), the reduction is carried out, the materials are crushed and ball-milled after cooling, vanadium is extracted by hydrolysis, and titanium is recovered. The inventor finds that: 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 coal consumption for reducing one ton of metal iron reaches more than 1000 kilograms, and the gas of more than 6GJ is needed for supplementary heating, so that the economy is poor. Therefore, it is desirable to provide a method for reducing vanadium titano-magnetite at low temperature.

The invention provides a method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite, which comprises the following steps:

step S1, mixing, uniformly mixing and molding the vanadium titano-magnetite fine powder, the carbonaceous reducing agent, the sodiumizing agent and the binder according to the mass ratio to obtain pellets, and drying the pellets;

s2, allowing the dried pellets to enter a reduction device for sodium salt reduction, wherein the highest temperature in the furnace is 850-950 ℃, and the reaction time is 60-240 min; wherein, the reduction device adopts an indirect heating (combustion flame is not directly contacted with the materials) device which can be heated above and below the materials (such as pellets);

s3, cooling the reduced metallized pellets, crushing, ball-milling to below 100 meshes, hydrolyzing with the pH value controlled to be above 12, and separating to obtain a slag iron mixture of iron powder and titanium-containing slag and a first filtrate;

step S4, separating the slag-iron mixture by a magnetic separator to obtain slag and metal iron powder; then drying the metal iron powder to obtain primary metal iron powder with the total iron of more than 95 percent, wherein the slag after magnetic separation is titanium-containing slag;

step S5, performing primary carbonation on the first filtrate, adjusting the pH value to 9-10, and promoting SiO₂、Al₂O₃Precipitating, filtering and separating to obtain SiO₂、Al₂O₃Precipitating and filtering the solution to obtain a second filtrate;

step S6, performing secondary carbonation on the second filtrate, adjusting the pH value to 8.5-9, adding ammonium sulfate or ammonium chloride to precipitate vanadium (room temperature), and adding an oxidant in the vanadium precipitation process to promote the formation of ammonium metavanadate precipitate; filtering and separating to obtain ammonium metavanadate precipitate and a third filtrate; the ammonium metavanadate is washed by water, dried and calcined into V₂O₅；

And step S7, performing carbonization for three times on the third filtrate, adjusting the pH value to 8.3-8.5 to form a sodium bicarbonate solution, evaporating and crystallizing to obtain a sodium bicarbonate solid, and drying or calcining the sodium bicarbonate solid to be used as a sodium treatment agent.

It should be noted that, the inventors have found through long-term intensive studies that:

the sodium salt reduction temperature of the vanadium titano-magnetite is normally higher than 1100 ℃, such as tunnel kiln reduction. The material distribution mode of the tunnel kiln is annular material distribution, materials are placed in a silicon carbide tank with the diameter of 400-500 mm for heating, the reduction heat transfer is slow, the reduction rate is slow, the reduction time is greatly increased, and the coal consumption is increased; and because the use amount of the coal is greatly increased, the content of S in the subsequent molten iron reaches over 0.5 percent, and the desulfurization cost of steel making is increased. And because the melting point of sodium carbonate is low, easy to volatilize, and the corrosivity is strong, therefore the problem that this method brings is that the number of times of using of carborundum is only several, and manufacturing cost is too high, and the alkali that volatilizees in addition has produced extremely strong corrosivity to the resistant material of tunnel cave, reduces the life of the resistant material of tunnel cave, and economic benefits is poor. Therefore, the invention adopts an indirect heating mode, namely the combustion flame is not directly contacted with the pellets, and parameters such as the granularity of raw materials, the paving thickness and the like are controlled to ensure that the reaction temperature of the vanadium-titanium magnetite is reduced to 850-950 ℃, the reaction time is 60-240 min, the reduction rate of iron in the vanadium-titanium magnetite can be ensured to exceed 95%, and the requirement of mass production is met. Thereby ensuring the improvement of the reduction rate of the iron and reducing the carbon consumption.

Specifically, in step S1, the vanadium titano-magnetite concentrate powder mainly includes, by mass: T.Fe: 50% -60% of SiO₂：1.0％～3.0％，CaO：1.0％～2.0％，MgO：1.0％～4.0％，Al₂O₃：2.0％～4.0％，TiO₂：9.0％～15.0％，V₂O₅：0.2％～1.0％，S：0.1％～0.6％。

Specifically, in step S1, the sodium treatment agent includes at least one of sodium carbonate and sodium bicarbonate.

Specifically, in step S1, the sodium reagent is used to separate vanadium from iron and titanium in the vanadium titano-magnetite. The adding amount of the sodium reagent is determined according to TiO in the vanadium titano-magnetite₂、SiO₂、Al₂O₃、V₂O₅S, and the content of acidic oxides in ash in the reducing agent and the species of the sodifying agentThe class is related. In order to ensure that acid oxides such as vanadium oxide, silicon oxide, aluminum oxide and the like in the vanadium titano-magnetite fully react with a sodium treatment agent to form corresponding sodium salts, the mass ratio of the vanadium titano-magnetite fine powder to the sodium treatment agent is controlled to be 100: 25 to 55.

Specifically, in step S1, in order to satisfy the requirement of reducing iron in the vanadium titano-magnetite, the carbon content is lower than that of carbon: the overall specific molar ratio of oxygen. The inventor finds out through intensive research that: the mass ratio of the vanadium titano-magnetite fine powder to the carbonaceous reducing agent is 100: 15 to 25.

Specifically, in step S1, the carbonaceous reducing agent may be pulverized coal or the like.

Specifically, in the step S1, cold press molding is adopted for molding, a binder is used, in order to reduce the gangue content mixed into the pellets, an organic binder is preferably used, and the mass ratio of the binder to the vanadium titano-magnetite fine powder is 2-8: 100.

specifically, in the step S1, the too large particle size (referred to as average particle size) of the prepared pellets may result in high reaction temperature, slow reaction speed and insufficient reaction; too small a particle size (referred to as an average particle size) results in difficulty in separating slag and iron powder after reduction; therefore, the average particle size of the pellets is controlled to be 30-50 mm. Specifically, the pellets are ellipsoids.

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 entering the reduction apparatus.

Specifically, in step S2, the temperature is too high, the time is too long, sintering is easy, and energy is wasted; the temperature is too low, the time is too short, and the reduction effect is poor; therefore, the reaction temperature in the reduction device is controlled to be 850-950 ℃, and the reaction time is controlled to be 60-240 min.

Specifically, in step S2, since the reduction of the vanadium titano-magnetite belongs to carbothermal reduction and strong endothermic reaction, the interior of the material basically needs heat conduction and heat supply, and if the thickness of the material is too large, the heat transfer speed is slow and the reaction speed is slow; the material thickness is too small, the single treatment capacity is too small, and the production efficiency is low. The thickness of the material is controlled not to exceed 80mm, and the thickness of the material is 20-60 mm, such as 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm and 60 mm.

Specifically, in step S2, the upper side and the lower side of the material (e.g., pellets) in the reduction apparatus can be heated, so that the upper side and the lower side can be heated together, and the heating efficiency can be improved.

Specifically, in step S2, the reduction device employs indirect heating (i.e., the combustion flame does not directly contact the material); compared with the device adopting internal combustion heating, the device adopting internal combustion heating has the advantages that due to the weak oxidizing atmosphere of combustion, the coal consumption required for achieving the same reduction rate is large, the invention adopts an indirect heating mode for reduction, the reducing atmosphere in the furnace can be ensured, the reduced materials can be ensured not to be subjected to secondary oxidation in the furnace, and the required reducing agent amount is small (if the vanadium titano-magnetite is reduced and then is subjected to secondary oxidation again and then is reduced to the target metallization rate or reduction rate, the consumed reducing agent amount is definitely large, if the atmosphere can be ensured, the secondary oxidation can not occur after the reduction, and the consumed reducing agent amount is definitely small).

Specifically, in step S2, the reduction device may be a steel belt furnace, a pusher furnace, or the like.

Specifically, in step S2, the reduction device may be a closed steel strip heating furnace, the indirect heater of the closed steel strip heating furnace is a U-shaped heat radiation tube, a W-shaped heat radiation tube, a P-shaped heat radiation tube, or a straight heat radiation tube, and the material of the heat radiation tube is high-temperature heat-resistant steel or nickel-based alloy; the metal shell can be heated by burning a common burner, and then the metal shell transfers heat to the materials inside. The indirect heating mode has good heat transfer effect and high heating efficiency.

Specifically, in step S3, the reduced metallized pellets need to be crushed and ball-milled to 100 mesh for subsequent slag hydrolysis and magnetic separation.

Specifically, in step S3, since the reduction temperature is low, vanadium can only exist in the valence state of trivalent vanadium, and NaVO is formed during sodium reduction₂。

Specifically, in step S3, in the hydrolysis process, the pH of the water is controlled to be 12 or more, so that vanadium is changed into soluble vanadate, and the soluble vanadate is separated from iron and titanium, thereby improving the slag quality.

Specifically, in step S3, the first filtrate contains NaVO₂、Na₂SiO₃、NaAlO₂NaOH, etc.

Specifically, in step S3, the hydrolysis process should be performed by stirring, such as mechanical stirring or manual stirring, to improve the hydrolysis kinetics.

Specifically, in the step S3, the number of hydrolysis times may be multiple, for example, 3 to 6 hydrolysis times.

Specifically, in step S4, the hydrolyzed slag-iron mixture is separated by magnetic separation to obtain slag and metal iron powder, where the slag is titanium-containing slag. The titanium-containing slag can be directly sold, and can also be further processed to obtain titanium dioxide.

Specifically, in step S4, the wet magnetic separator is selected for magnetic separation in the present invention, because the wet magnetic separation effect is better than the dry magnetic separation effect.

Specifically, in step S4, the metal iron powder is dried to obtain a primary metal iron powder with total iron of more than 95%, and the primary metal iron powder can be sold as a metal iron powder, or can be used as a cold-pressed block to enter the iron and steel smelting industry as high-grade sponge iron.

Specifically, in step S4, the primary metal iron powder may be continuously reduced by hydrogen to obtain a secondary metal iron powder with total iron exceeding 97%, and the reduction temperature of hydrogen reduction is 900-1000 ℃ for 60-180 min, which is mainly to remove residual alkali, residual oxygen and residual carbon in the primary reduced iron powder. The hydrogen can be pure hydrogen or nitrogen-hydrogen mixed gas decomposed by liquid ammonia.

Specifically, in step S5, Na in the first filtrate₂SiO₃、NaAlO₂The hydrolysis is started when the pH value is 11, and the hydrolysis can be completed when the pH value is 9-10. There are many ways to adjust pH, such as adding sulfuric acid or hydrochloric acid directly, but sodium sulfate or sodium chloride is generated after reaction, which is not easy to be recycled in the whole process; the wastewater amount is too large by directly adding water to adjust the pH value, so in the invention, the carbon content mode is selected to filter the wastewater to the first stageIntroducing CO into the liquid₂Gas to adjust the pH. The pellet of the invention generates CO containing residual heat in the process of reduction roasting₂Gas, which can be CO in this step₂And the gas source greatly reduces the cost of adjusting the pH value.

Specifically, by the above step S5, SiO₂、Al₂O₃Removing, wherein the second filtrate also contains NaVO₂、NaOH、Na₂CO₃Etc.; therefore, the CO content continues to be introduced in step S6₂Adjusting the pH value of the gas, when the pH value is stabilized at 8.5-9, adopting oxidants such as hydrogen peroxide to convert vanadium with valence 3 into vanadium with valence 5, adding ammonium sulfate or ammonium chloride to precipitate vanadium, washing the generated ammonium metavanadate, drying and calcining to obtain V₂O₅。

Specifically, in step S6, the reaction equation involved in the vanadium deposition process includes:

VO₂ ^-+NH₄ ⁺+[O]^-＝NH₄VO₃↓+e^-

specifically, in step S6, the calcination temperature is 450 to 600 ℃.

Specifically, in the step S7, the third filtrate mainly contains sodium carbonate, sodium hydroxide, and a small amount of sodium sulfate, which can be directly evaporated and crystallized, but the crystallized sodium salt product contains sulfate, which accelerates corrosion of refractory materials; therefore, the invention continues to conduct carbonation, and the pH value is adjusted to 8.3-8.5 to form the sodium bicarbonate solution. Sodium bicarbonate has low solubility and sodium sulfate has high solubility, so that sodium bicarbonate solid is obtained through evaporation and crystallization, and after liquid-solid separation, the sodium bicarbonate solid is dried or calcined at low temperature and then is used as a sodium modifier. And the final liquid containing sodium sulfate needs to be continuously evaporated, crystallized and dried to obtain anhydrous sodium sulfate.

Compared with the prior art, the method disclosed by the invention has the advantages that the granularity of the pellets is controlled to be 30-50 mm, the indirect heating devices which can be heated above and below the materials are adopted for heating reduction, the thickness of the materials is controlled to be below 80mm, the reaction temperature of the vanadium-titanium magnetite can be reduced to 850-950 ℃, the reaction time is 60-240 min, the reduction rate of iron in the vanadium-titanium magnetite can be ensured to exceed 95%, and the requirement of mass production can be met.

The method reduces the sodium reduction roasting temperature of the vanadium titano-magnetite, obviously weakens the corrosivity and volatilization of alkali when the temperature in the furnace is 850-950 ℃, greatly reduces the corrosivity to equipment, and is beneficial to the long-term operation of production.

The method adopts an indirect heating device (i.e. combustion flame is not directly contacted with the material) which can be heated above and below the material to carry out heating reduction; compared with the device adopting internal combustion heating, the device adopting internal combustion heating has large coal consumption required for reaching the same reduction rate due to the weak oxidizing atmosphere of combustion.

The reaction temperature of the method is low, so the required amount of the iron-coal powder per ton is lower than 400 kg, and is far lower than 1000 kg of coal consumption reduced by a tunnel kiln; greatly saves energy and reduces carbon emission.

In the method, the addition amount of the coal powder is small, so that the S content in the final iron powder is 0.1-0.2%, and the smelting sulfur load of the subsequent process is greatly reduced.

The method of the invention produces CO-containing gas by heating reduction₂The waste heat flue gas is used as a raw material for regulating the pH value of the solution, so that the pH value regulating cost is greatly reduced, the waste water evaporation capacity of the system is greatly reduced, the evaporation and crystallization cost is greatly reduced, and in addition, the recycling of sodium salt in the system is promoted.

The method can produce high-quality metal iron powder or high-grade sponge iron and high-quality metal iron V with low cost and low carbon emission₂O₅And the titanium-containing slag, so that the green high-added-value utilization of vanadium, titanium and iron of the vanadium-titanium magnetite is realized.

Example 1

The embodiment provides a method for realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite, and the method is adopted, and a process flow chart is shown in figure 1. The specific details are as follows:

the main components of the vanadium titano-magnetite fine powder used in the present example are shown in table 1; the main components of the coal dust used as the reducing agent are shown in Table 2; the sodium agent is sodium bicarbonate, the purity is higher than 95%, and the binder is organic binder.

The vanadium titano-magnetite fine powder, the carbonaceous reducing agent, the sodium bicarbonate and the binder are mixed according to the mass ratio of 100: 18: 31: and 5, preparing materials, uniformly mixing, and performing cold press molding to obtain pellets, wherein the pellets are ellipsoid and have the particle size of 35-50 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 a heating reduction device for sodium treatment reduction, the spreading thickness is 50mm, the reduction device adopts indirect heating, the maximum temperature of the materials is 940 ℃, the reaction time is 80min, and the pellet metallization rate is 95%; cooling the metallized pellets, crushing, ball-milling to 100 meshes to be fine, then hydrolyzing in deionized water, controlling the pH value to be 13, mechanically stirring in the hydrolysis process, hydrolyzing at normal temperature for 3 times, 25min each time, and separating after hydrolysis to obtain a slag iron mixture and a first filtrate.

Separating the slag-iron mixture by a magnetic separator to obtain metal iron powder and titanium-containing slag; then drying the metal iron powder, and reducing the metal iron powder by pure hydrogen to obtain secondary metal iron powder with total iron content of 98.2 percent, wherein the reduction temperature is 1000 ℃ and the time is 60 min; the titanium-containing slag after magnetic separation contains TiO₂ 51％。

Performing carbonation on the first filtrate obtained after hydrolysis and separation by using waste flue gas generated by a reduction device, adjusting the pH value to 9.3, controlling the solution temperature at 68 ℃ and promoting SiO₂、Al₂O₃Precipitating; performing further carbonation on the filtrate obtained after the solid-liquid separation of the plate frame, adjusting the pH value to 8.7, adding ammonium sulfate to precipitate vanadium at room temperature, and adding hydrogen peroxide into the precipitated vanadium to form ammonium metavanadate precipitate; 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(ii) a And (4) continuously carbonizing the filtrate after vanadium precipitation at 53 ℃, adjusting the pH value to 8.3 to form a sodium bicarbonate solution, and evaporating and crystallizing to obtain sodium bicarbonate. The residual liquid is continuously evaporated, crystallized and dried to obtain anhydrous sodium sulphate.

TABLE 1 Main Components/wt% of the refined vanadium titano-magnetite fines

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 realizing comprehensive utilization of iron, vanadium and titanium by low-temperature reduction roasting of vanadium titano-magnetite, and the method is adopted, and a process flow chart is shown in figure 1. The specific details are as follows:

the main components of the vanadium titano-magnetite fine powder used in the present example are shown in table 3; the reducing agent is pulverized coal as shown in Table 4; the sodium agent is sodium bicarbonate, the purity is higher than 95%, and the binder is organic binder.

The vanadium titano-magnetite fine powder, the carbonaceous reducing agent, the sodium bicarbonate and the binder are mixed according to the mass ratio of 100: 21: 48: 8, preparing materials, uniformly mixing, and performing cold press molding to obtain pellets, wherein the pellets are ellipsoid and have the particle size of 30-40 mm. The pellets are dried on a continuous dryer, the temperature of the drying air inlet is 300 ℃, the pellets stay for 30min, and the moisture of the pellets is 1.5 percent.

The pellets enter a heating reduction device for sodium treatment reduction, the spreading thickness is 40mm, the reduction device adopts indirect heating, the maximum temperature of the materials is 900 ℃, the reaction time is 160min, and the pellet metallization rate is 95%; cooling the metallized pellets, crushing, ball-milling to 100 meshes to be fine, then hydrolyzing in deionized water, controlling the pH value to be 12.5, mechanically stirring in the hydrolysis process, hydrolyzing for 3 times at room temperature for 30min each time, and separating after hydrolysis to obtain a slag iron mixture and a first filtrate.

Separating the slag-iron mixture by a magnetic separator to obtain metal iron powder and titanium-containing slag;then drying the metal iron powder to obtain metal iron powder with total iron content of 95.5%; the titanium-containing slag after magnetic separation contains TiO₂54％。

Performing carbonation on the first filtrate obtained after hydrolysis and separation by using waste flue gas generated by a reduction device, controlling the temperature of the solution at 65 ℃, adjusting the pH value to 9.5, and promoting SiO₂、Al₂O₃Precipitating; performing further carbonation on the filtrate obtained after the solid-liquid separation of the plate frame, adjusting the pH value to 8.8, adding ammonium sulfate to precipitate vanadium at room temperature, and adding hydrogen peroxide into the precipitated vanadium to form ammonium metavanadate precipitate; 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；

And (3) continuously carbonizing the filtrate after vanadium precipitation at 55 ℃, adjusting the pH value to 8.4 to form a sodium bicarbonate solution, and evaporating and crystallizing to obtain sodium bicarbonate. The residual liquid is continuously evaporated, crystallized and dried to obtain anhydrous sodium sulphate.

TABLE 3 Main Components/wt% of the refined vanadium titano-magnetite fines

T.Fe	SiO2	CaO	MgO	Al2O3	TiO2	V2O5	S
								55.95	1.99	1.15	2.32	3.45	12.65	0.58	0.64

TABLE 4 pulverized coal main component

Fixed carbon	Volatile matter	Ash content	S
				75.13％	12.36％	12.16％	0.35％

In the above example 1-2, the coal powder consumption per ton of iron is 340-390 kg; far lower than 1000 kg coal consumption of tunnel kiln reduction. Therefore, the method has low coal consumption and low carbon emission; the economic benefit is remarkable.

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.