CN113462842A

CN113462842A - Method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature

Info

Publication number: CN113462842A
Application number: CN202110603669.XA
Authority: CN
Inventors: 王磊; 郭培民; 孔令兵; 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: 2021-05-31
Filing date: 2021-05-31
Publication date: 2021-10-01

Abstract

The invention discloses a method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at a low temperature, belongs to the technical field of comprehensive utilization of ilmenite resources, and solves the problems of low effective utilization rate of energy and difficult separation of high-titanium slag and iron in the conventional electric furnace smelting method. The method comprises the following steps: step S1, blending the ilmenite concentrate powder, the powdery reducing agent, the powdery sodium carbonate and/or the sodium bicarbonate; s2, placing the uniformly mixed materials in an indirect heating reduction device for heating reduction to obtain a metallized mixture, wherein the reaction temperature in the indirect heating reduction device is 950-1100 ℃, and the reaction time is 80-200 min; s3, crushing and ball-milling the cooled metalized mixture until the granularity is smaller than 100 meshes, and performing magnetic separation; step S4, dehydrating the iron powder after magnetic separation, and then drying to obtain metal iron powder; and S5, washing, dehydrating and drying the high titanium slag subjected to magnetic separation to obtain high titanium slag powder. The method of the invention can produce high-quality high-titanium slag powder and metal iron powder with low coal consumption and low carbon emission.

Description

Method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature

Technical Field

The invention relates to the technical field of comprehensive utilization of resources of ilmenite, in particular to a method for preparing high-titanium slag powder and metallic iron powder by reducing ilmenite concentrate powder at a low temperature.

Background

At present, more than 90% of the titanium ore in the world is used for producing titanium white, about 4-5% of the titanium ore is used for producing metallic titanium, and the rest of the titanium ore is used for manufacturing welding electrodes, alloys, carbides, ceramics, glass, chemicals and the like. The titanium resource reserves in China are very rich, but ilmenite and rutile ore are few. The titanium ore in China is mainly produced by mining Guangdong, Guangxi, Hainan, Yunnan and Panzhihua in Sichuan, and the main product is ilmenite concentrate and also has a small amount of rutile concentrate. Because the grade of ilmenite concentrate is low, high-grade titanium-rich materials, namely high titanium slag or artificial rutile, are usually obtained through enrichment treatment, and then the next treatment can be carried out.

The existing electric furnace smelting method for treating ilmenite is a mature method, the process is simple, the byproduct metallic iron can be directly utilized, solid and liquid waste materials are not generated, electric furnace gas can be recycled, three wastes are less, the occupied area of a factory is small, and the method is an efficient smelting method. However, the effective utilization rate of energy of the electric furnace smelting method is only about 17 percent, and certain environmental pollution exists.

At home and abroad, a method for reducing ilmenite at 1200-1250 ℃, and then magnetically separating titanium slag and iron is provided, but at the temperature, only a tunnel kiln can meet the requirement of indirect reduction, but the mass of a tunnel kiln trolley and a tank body is far larger than that of ferrotitanium fine powder in the tank, so that the coal consumption for smelting titanium slag per ton exceeds 1000 kg, the service life of silicon carbide tank materials is short, and the method is not economical.

The inventor proposes that the superfine ilmenite concentrate powder is reduced at a temperature below 800 ℃, but the granularity of the ore powder needs to be smaller than 10 microns, and the technology is not easy to realize industrialization.

Disclosure of Invention

In view of the above analysis, the present invention provides a method for preparing high titanium slag powder and metallic iron powder by reducing ilmenite concentrate powder at low temperature, which can solve at least one of the following technical problems: (1) the effective utilization rate of energy of the electric furnace smelting method is low, and environmental pollution exists; (2) the low-temperature reduction of the superfine ilmenite concentrate powder is not easy to industrialize, and the separation of high-titanium slag and iron is difficult.

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

the invention provides a method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature, which comprises the following steps:

step S1, blending and uniformly mixing: mixing ilmenite concentrate powder, a powdery reducing agent, powdery sodium carbonate and/or sodium bicarbonate; wherein the granularity of the ilmenite concentrate powder is below 325 meshes;

step S2, heating reduction: the mixed materials are put into an indirect heating reduction device for heating reduction to obtain a metallized mixture, the reaction temperature in the indirect heating reduction device is 950-1100 ℃, the reaction time is 80-200 min, and the reduction rate of iron after reduction of the ilmenite concentrate powder is more than 95%;

step S3, crushing, ball milling and magnetic separation: crushing and ball-milling the cooled metalized mixture until the granularity is smaller than 100 meshes, and performing magnetic separation to obtain metallic iron and titanium slag;

step S4, dehydrating and drying iron powder: dehydrating the iron powder subjected to magnetic separation, and then drying in indirect drying equipment to obtain metal iron powder with the total iron mass percentage content of more than 92%;

step S5, washing, dehydrating and drying the titanium slag: washing, dehydrating and drying the magnetically-separated high-titanium slag to obtain TiO₂More than 90 wt% of high titanium slag powder.

Further, in step S1, the mass percent of CaO in the ilmenite concentrate powder is less than 0.5%, and the mass percent of MgO is less than 1%.

Further, in step S1, the mass ratio of the ilmenite concentrate powder, the powdery reducing agent, the powdery sodium carbonate and/or the sodium bicarbonate is 100: 10-20: 0 to 10.

Further, in step S1, the average particle size of the powdered reducing agent, the powdered sodium carbonate and/or the powdered sodium bicarbonate is smaller than 100 meshes.

Further, in the step S2, the thickness of the material is controlled not to exceed 60 mm.

Further, in step S2, the indirect heating reduction device is a steel belt heating furnace or a boat pushing furnace.

Further, in the step S2, the indirect heating and reducing device may adopt gas heating, resistance wire heating, or microwave heating.

Further, in the step S2, the grain size of the metallic iron in the reduced metalized mixture is 0.1mm or more.

Further, in step S3, a wet magnetic separator is selected for magnetic separation.

Further, the step S1 further includes:

s101: cold-press molding the uniformly mixed materials to obtain pellets, and drying the pellets; the dried pellets may be added to the indirect heating reduction apparatus to continue the steps S2-S5.

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

(1) the method can control the reaction temperature to 950-1100 ℃ by controlling the granularity of the ilmenite concentrate powder below 325 meshes, can ensure that the reduction rate of iron in the ilmenite concentrate powder exceeds 95 percent by adding sodium carbonate (and/or sodium bicarbonate) and adding 10-20 percent of reducing agent, the material thickness does not exceed 60mm, and the reaction time is controlled to 80-200 min, and simultaneously provides a favorable basis for magnetic separation because the granularity of the metal iron reaches above 0.1mm, and can obtain the metal iron powder and the high titanium slag powder (TiO) with the total iron content of more than 92 percent by mass after the magnetic separation₂More than 90%), the separation effect of the high titanium slag powder and the iron powder is good.

(2) The method of the invention adopts a small amount of reducing agent and has low reaction temperature, thus the total coal consumption is low. The amount of the coal powder of 1 ton of high-quality high-titanium slag is 150-280 kg (related to coal types), the power consumption is 200kWh, which is far lower than that of over 2000kWh smelted by the existing electric furnace and 1000 kg reduced by a tunnel kiln, the energy is greatly saved, and the carbon emission is reduced; high-quality high-titanium slag powder and metal iron powder can be produced with low coal consumption, low power consumption and low carbon emission, and green high-added-value utilization of the ilmenite concentrate powder 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 example 1;

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

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.

The existing electric furnace smelting method for treating ilmenite is a mature method, the process for treating ilmenite by the electric furnace smelting method is simple, the byproduct metallic iron can be directly utilized, solid and liquid waste materials are not generated, electric furnace gas can be recycled, three wastes are less, the occupied area of a factory is small, and the method is an efficient smelting method. However, because the electric furnace smelting method belongs to high-temperature metallurgy, the high energy consumption is the inherent characteristic, about 2500kWh of electric energy is needed for producing 1 ton of high-titanium slag, and the chemical energy needed for actually reducing iron from ilmenite is only about 500kWh, namely, the effective utilization rate of the energy is only about 17 percent and is very low; secondly, the electric furnace smelting method uses metallurgical coke or petroleum coke as a reducing agent, and has certain environmental pollution.

The inventor proposes that the superfine ilmenite concentrate powder is reduced at a temperature below 800 ℃, but the granularity of the ore powder needs to be smaller than 10 microns, and the technology is not easy to realize industrialization due to the limitation of a large-scale powder preparation process. The inventor finds that the iron powder is too fine in the reduction process at the temperature of below 800 ℃ of the superfine ilmenite concentrate powder, and the separation of high titanium slag and the iron powder is difficult.

step S1, blending and uniformly mixing: mixing ilmenite concentrate powder, a powdery reducing agent, powdery sodium carbonate and/or sodium bicarbonate; wherein the granularity of the ilmenite concentrate powder is less than 325 meshes (0.045 mm);

step S2, heating reduction: the mixed material is put into an indirect heating reduction device for heating reduction to obtain a metallized mixture, the reaction temperature in the indirect heating reduction device is 950-1100 ℃, the reaction time is 80-200 min, and the reduction rate of iron in the reduced ilmenite concentrate powder is more than 95 percent;

step S3, crushing, ball milling and magnetic separation: crushing and ball-milling the cooled metalized mixture until the granularity is smaller than 100 meshes, and separating by a wet magnetic separator to obtain metallic iron and titanium slag;

step S5, washing, dehydrating and drying the titanium slag: washing, dehydrating and drying the magnetically-separated high-titanium slag to obtain high-titanium slag powder (TiO)₂Greater than 90%).

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

the main phase in ilmenite is FeTiO₃If the particle size of the ilmenite concentrate powder is around 100 microns, the theoretical thermodynamic minimum reduction temperature is around 810 ℃. In practice, the reaction is kinetically limited, and even at 1200 ℃, the reaction rate is slow. This tooIs one of the reasons for producing the high titanium slag by using the electric furnace smelting method at present.

The inventor finds that: in the heating reduction process of ilmenite, the granularity of raw materials is one of important parameters of reaction speed, and the granularity is simply used for reducing the temperature, so that ilmenite concentrate powder with the granularity smaller than 10 microns can be reduced at the temperature below 800 ℃ as mentioned by the inventor. Firstly, however, the large-scale preparation of powders with the raw material of less than 10 microns has difficulties; secondly, the reduction below 800 ℃ is also unfavorable for the separation of iron and titanium slag, because the powder is too fine and the temperature is low, so that the metallic iron is not easy to promote to grow to the level of 0.1mm, even if the iron is fully reduced, the separation effect of the iron and the slag is poor (the metallic iron is too fine and is not beneficial to separation during magnetic separation), and the metallic iron and the titanium slag cannot achieve the expected separation effect. Therefore, the ilmenite has difficulty in low-temperature reduction and also has the problem of high difficulty in fully separating the metallic iron from the titanium slag.

Accordingly, the inventors have proposed a method of reducing ilmenite with an appropriate increase in reaction temperature, in which the particle size of the raw material can be moderately relaxed (for example, the average particle size of ilmenite concentrate powder as the raw material is 325 mesh (0.045mm) or less), facilitating the mass-production of powder at low cost; meanwhile, the inventor adds sodium carbonate and/or sodium bicarbonate, and the sodium carbonate or the sodium bicarbonate can improve the reaction speed, reduce the temperature of the metal iron, promote the aggregation of the iron powder, promote the growth of the crystal grains of the metal iron and is beneficial to improving the separation effect of the metal iron and the titanium slag. And the addition of sodium carbonate and sodium bicarbonate does not increase the impurities in the product.

Specifically, in step S1, the ilmenite concentrate powder mainly includes, in mass percent: FeO: 25 to 45 percent of TiO₂: 35% -60%, wherein, T.Fe: 30 to 40 percent.

Considering that the production process can effectively remove impurities, but the impurity removal capability of the production process is limited, so in order to improve the quality of the reduced high titanium slag and metallic iron, the components of the raw materials entering the furnace need to be limited, and as CaO and MgO cannot be removed in the reduction and subsequent magnetic separation, and the content of CaO and MgO is too high, the CaO and MgO can react with the main phase of ilmenite, which is not beneficial to the subsequent separation and removal and influences the separation and recovery of iron and titanium; therefore, in step S1, the mass percent of CaO and the mass percent of MgO in the ilmenite concentrate powder are controlled to be less than 0.5% and less than 1%.

Specifically, in step S1, the reducing agent is a carbonaceous reducing agent such as coal powder, and the quality of the titanium slag is related to the components of the ilmenite concentrate powder and the components of the added reducing agent, so that the influence of ash in the reducing agent needs to be reduced in order to improve the quality of the reduced high titanium slag and metallic iron, and therefore, in step S1, the ash content of the reducing agent is controlled to be less than 10%.

Specifically, in the above step S1, sodium carbonate or sodium bicarbonate has similar properties and is a high-quality catalyst, and in the present invention, it can accelerate the reduction reaction and promote the growth of metallic iron grains, and at the same time, it can also react with SiO in the slag₂、Al₂O₃And reacting to partially generate soluble silicate and aluminate, and finally improving the quality of the titanium slag. However, sodium carbonate or sodium bicarbonate starts to volatilize above 850 ℃, and the higher the temperature is, the more serious the volatilization is, and the corrosion to refractory materials in the furnace is increased. In the invention, the adding mass percent of sodium carbonate or sodium bicarbonate is controlled to be less than 10 percent, and considering that the reaction temperature is high, the reaction rate is high, and the amount of the required catalyst is small, therefore, in the reduction process of 950-1000 ℃, if the reaction temperature is low, the adding amount of the sodium carbonate or sodium bicarbonate can be more, and the temperature reaches 1100 ℃, little or no addition is needed. Specifically, the method comprises the following steps: the reaction temperature, the particle size of the raw material and the addition amount of sodium carbonate or sodium bicarbonate are related as follows: the finer the particle size of the raw material is, the more the addition amount of sodium carbonate or sodium bicarbonate is, and the lower the required reaction temperature is; the coarser the starting material particle size, the less sodium carbonate or bicarbonate is added and the higher the reaction temperature required.

Specifically, in step S1, if the content of the powdery reducing agent is too high, there is residue after the reaction, and the material is wasted; too low, the reduction is incomplete. Therefore, the mass ratio of the ilmenite concentrate powder, the powdery reducing agent, the powdery sodium carbonate and/or the sodium bicarbonate is controlled to be 100: 10-20: 0 to 10. When the reaction temperature is high, the amount of sodium carbonate and/or sodium bicarbonate to be added may be 0.

The amount of the powdery reducing agent is in accordance with Fe₂O₃The equation for the reduction of FeO by C is calculated as follows:

Fe₂O₃+3C＝Fe+3CO

FeO+C＝Fe+CO

specifically, in the step S1, the excessive particle size (referred to as the average particle size) of the ilmenite concentrate powder results in high reaction temperature, slow reaction speed and insufficient reaction; the undersize of the ilmenite concentrate powder (which refers to the average particle size) can cause low required reaction temperature and difficult separation of reduced titanium slag and iron powder; therefore, the average particle size of the ilmenite concentrate powder is controlled to be smaller than 325 meshes, and exemplarily, the average particle size of the ilmenite concentrate powder is 325-625 meshes.

Specifically, in step S1, the contact area between the powdered sodium carbonate and the ilmenite concentrate powder is small due to the excessively large particle size of the powdered sodium carbonate and/or the powdered sodium bicarbonate, and the reduction and catalysis effects are poor; the granularity is too small, so that the mixing uniformity of the powdery reducing agent, the powdery sodium carbonate and/or the powdery sodium bicarbonate and the ilmenite concentrate powder is poor, and the reduction and catalysis effects are poor; therefore, the average particle size of the powdery reducing agent, the powdery sodium carbonate and/or the powdery sodium bicarbonate is controlled to be smaller than 100 meshes.

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 950-1100 ℃, and the reaction time is controlled to be 80-200 min. The higher the reaction temperature, the shorter the reaction time required. The thicker the cloth, the longer the required reaction time. The more sodium carbonate and/or sodium bicarbonate is added, the shorter the reaction time required and the higher the temperature required.

Specifically, in the step S2, since the reduction of the ilmenite concentrate powder belongs to the carbothermic reduction and the strong endothermic reaction, heat conduction and heat supply are basically required in the material, and if the thickness of the material is too large, the heat transfer speed is slow, the reaction speed is slow, and the metallic iron crystal grains are not easy to grow up; the thickness of the material is too large, the single treatment capacity is too small, and the production efficiency is low. The thickness of the material is controlled not to exceed 60mm, 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 particle size of the iron powder in the mixture obtained after reduction reaches 0.1mm or more, which is beneficial to subsequent magnetic separation. After reduction roasting, the metallic iron with the reduction rate of more than 95% and the grain size of more than 0.1mm (for example, the grain size of more than 0.15mm) is obtained, which provides a basis for subsequent separation. The research shows that the granularity of the metallic iron and the slag is coarser than 100 meshes (0.15mm), and the separation rate of the metallic iron and the titanium slag is more than 95 percent.

In step S2, the reaction equipment is important in order to achieve a reduction ratio of iron in the ilmenite concentrate powder of more than 95%, and if internal combustion heating equipment such as a rotary hearth furnace heating system is used, a reduction ratio of 95% cannot be obtained due to a weakly oxidizing atmosphere of combustion. The rotary kiln can theoretically realize reduction at 950-1100 ℃, but the rotary kiln is also an internal heating mode, and in order to ensure the reducing atmosphere, more coal needs to be added, so that not only is the coal consumption increased, but also the quality of the high titanium slag is influenced by the coal ash and the excess coal. The inventor finds that the reduction atmosphere in the furnace can be ensured and the metallization rate of iron can be ensured to exceed 95% by adopting an indirect heating mode, such as a steel belt type heating furnace or a push boat furnace. Compared with the device adopting internal combustion heating, the device adopting internal combustion heating has the advantages that the coal consumption required for achieving the same reduction rate is large due to the weak oxidizing atmosphere of combustion, the indirect heating reduction mode is adopted, the reducing atmosphere in the furnace can be ensured, the reduced powder particles can be ensured not to be subjected to secondary oxidation in the furnace (if the ilmenite concentrate powder is reduced and then secondarily oxidized and then reduced to the target metallization rate or reduction rate, the consumed reducing agent coal amount is definitely large, if the atmosphere can be ensured, the secondary oxidation cannot occur after the reduction, and the consumed reducing agent coal amount is definitely small), the required reducing agent amount is small, and the reducing agent amount can be greatly reduced.

Specifically, the steel boat of the boat pushing furnace has large mass and the heating energy consumption is increased, so 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 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 S3, in order to improve the separation effect of the metallic iron and titanium slag after the magnetic separation, a two-stage wet magnetic separator may be used as the wet magnetic separator.

Specifically, in the step S4, the indirect drying device is used for the iron powder dehydration, because the direct drying is likely to cause the iron powder to be oxidized again, which affects the quality of the iron powder.

Specifically, in the step S4, the drying temperature for iron powder dehydration is controlled to be 200-.

Specifically, in step S5, the titanium slag is washed with water to remove sodium salts and soluble silicates and aluminates, and then dehydrated and dried to obtain high titanium slag powder (TiO)₂Greater than 90%).

Specifically, in the step S5, the titanium slag may be dried by a roller, and the drying temperature of the titanium slag is controlled to 200-.

Specifically, in step S1, in order to reduce the amount of dust in the furnace in the large-scale production line, it is necessary to add ilmenite concentrate powder, a powdery reducing agent, powdery sodium carbonate and/or sodium bicarbonate into the heating reduction apparatus after pelletizing, so that the amount of dust in the furnace can be reduced, which is advantageous for long-term use of the production line. Therefore, the step S1 further includes:

s101: and (4) performing cold press molding on the uniformly mixed material to obtain pellets, and drying the pellets. The dried pellets may be added to the indirect heating reduction apparatus to continue the steps S2-S5.

Specifically, in the step S101, 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 preferably used, and the mass ratio of the binder to the ilmenite concentrate powder is 2-8: 100.

specifically, in step S101, the organic binder is one or more of sodium carboxymethyl cellulose, modified starch, acrylamide, sodium humate, and waste syrup.

Specifically, in step S101, the moisture content of the dried pellets is controlled to be 2% or less in order to reduce the decrepitation of the pellets entering the reduction facility.

Compared with the prior art, the method of the invention controls the particle size of the ilmenite concentrate powder below 325 meshes, can control the reaction temperature at 950-1100 ℃, and controls the material thickness to be not more than 60mm and the reaction time to be 80-200 min by adding sodium carbonate (and/or sodium bicarbonate) and adding 10-20% of reducing agent (related to the fixed carbon content of carbonaceous reducing agent and the components of the ilmenite concentrate powder), thereby ensuring that the reduction rate of iron in the ilmenite concentrate powder exceeds 95% and the particle size of metallic iron reaches more than 0.1mm, providing a favorable basis for magnetic separation, and obtaining metallic iron powder and high titanium slag powder (TiO) with the total iron content of more than 92% by mass after the magnetic separation₂More than 90%), high titanium slag and iron powder have good separation effect.

The amount of the coal powder of 1 ton of high-titanium slag obtained by the method is 150-280 kg (related to coal types), the power consumption is 200kWh, which is far lower than 2500kWh of the existing electric furnace smelting and 1000 kg of coal consumption reduced by a tunnel kiln, the energy is greatly saved, and the carbon emission is reduced; the method of the invention adopts a small amount of reducing agent and has low reaction temperature, thus the total coal consumption is low. High-quality high-titanium slag powder and metal iron powder can be produced with low coal consumption, low power consumption and low carbon emission, and green high-added-value utilization of the ilmenite concentrate powder is realized.

Example 1

The embodiment provides a method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature, which adopts the method and has a process flow chart shown in figure 1. The specific details are as follows:

the ilmenite concentrate powder used in this embodiment has an average particle size of 325 to 625 mesh, wherein 325 mesh corresponds to 45 micrometers, and 625 mesh corresponds to 20 micrometers. The main components are shown in Table 1. The reducing agent is coal powder, the components of the coal powder are shown in table 2, and the purity of the sodium carbonate is more than 95 percent. The granularity of the coal powder and the sodium carbonate is less than 100 meshes.

(1) Ferrotitanium concentrate powder, coal powder and sodium carbonate powder are mixed according to the mass ratio of 100: 18: 7, blending and uniformly mixing;

(2) the mixture enters an indirect heating reduction device for heating reduction, the maximum temperature in the furnace is 1000 ℃, the reaction time is 150min, the material thickness is 40mm, and the reduction rate of iron in the reduced ilmenite is 97 percent. Wherein, the indirect heating reduction device is a steel belt type heating furnace.

(3) And cooling the reduced metalized mixture, crushing and ball-milling to obtain a particle size of 150 meshes, and separating metal and titanium slag by using a two-stage wet magnetic separator.

(4) And (3) carrying out filter pressing and dehydration on the iron powder subjected to magnetic separation to reach the water content of 10% through a plate frame, and then drying the iron powder in an indirect drying furnace at the temperature of 300 ℃ for 60min, wherein the total iron in the metal iron powder is over 94.3%.

(5) Washing the titanium slag subjected to magnetic separation with water, dehydrating the titanium slag with a plate frame until the water content is 12%, and drying the titanium slag in a roller for 40min at the smoke temperature of 400 ℃ to obtain TiO in the high-titanium slag powder₂ 93.5％。

TABLE 1 Main component/wt% of ilmenite concentrates

T.Fe	FeO	TiO₂	SiO₂	CaO	MgO	Al₂O₃
							32.28	31.96	56.59	0.84	0.05	0.1	0.21

TABLE 2 coal fines principal component/wt.%

Fixed carbon	Volatile matter	Ash content	S
				56.00％	30.00％	6.50％	0.42％

Example 2

The ilmenite concentrate powder used in this example had an average particle size of 325 to 625 mesh, and the main components are shown in table 1. The reducing agent used was pulverized coal as shown in Table 3. The purity of the sodium carbonate and the sodium bicarbonate is more than 95 percent, and the mass ratio of the sodium carbonate to the sodium bicarbonate is 60: 40. the granularity of the coal powder, the sodium carbonate and the sodium bicarbonate is less than 100 meshes, and the binder is organic binder sodium carboxymethyl cellulose.

(1) Ilmenite fine powder, a carbonaceous reducing agent, sodium carbonate, sodium bicarbonate and a binder in a mass ratio of 100: 13: 2: and 5, preparing materials, uniformly mixing, and performing cold press molding to obtain the pellets, wherein the pellets are ellipsoids (about 50mm in length and about 30mm in width and height). 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 1.5%.

(2) The pellets enter an indirect heating reduction device for heating reduction, the maximum temperature in the furnace is 1080 ℃, the reaction time is 100min, the material thickness is 50mm, and the reduction rate of iron in the reduced ilmenite is 95%. Wherein, the indirect heating reduction device is a steel belt type heating furnace.

(3) And cooling the reduced metalized mixture, crushing and ball-milling to obtain a 100-mesh particle size, and separating metal and titanium slag by using a two-stage wet magnetic separator.

(4) And (3) carrying out filter pressing and dehydration on the iron powder subjected to magnetic separation to reach the water content of 9% through a plate frame, and then drying the iron powder in an indirect drying furnace at the temperature of 300 ℃ for 55min, so that the total iron content in the metal iron powder is 92.1%.

(5) Washing the magnetically-separated titanium slag with water, dehydrating the titanium slag with a plate frame until the water content is 13%, and drying the titanium slag in a roller at the smoke temperature of 400 ℃ for 45min to obtain high-titanium slag powder and TiO in the high-titanium slag powder₂92.2％。

Table 3 coal fines principal component/wt% of example 2

Fixed carbon	Volatile matter	Ash content	S
				79.29％	11.55％	8.50％	0.35％

Example 3

The embodiment provides a method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature, and the process flow is the same as that in embodiment 1. The specific details are as follows:

the ilmenite concentrate powder used in this example had an average particle size of 325 to 625 mesh, and the main components are shown in table 4. The reducing agent is coal powder, the components of the coal powder are shown in Table 5, and the purity of the sodium carbonate is more than 95 percent. The granularity of the coal powder and the sodium carbonate is less than 100 meshes.

(1) Ferrotitanium concentrate powder, coal powder and sodium carbonate powder are mixed according to the mass ratio of 100: 16: 7, blending and uniformly mixing;

(2) the mixture enters an indirect heating reduction device for heating reduction, the maximum temperature in the furnace is 950 ℃, the reaction time is 180min, the material thickness is 40mm, and the reduction rate of iron in the reduced ilmenite is 96%. Wherein, the indirect heating reduction device is a steel belt type heating furnace.

(4) And (3) carrying out filter pressing and dehydration on the iron powder subjected to magnetic separation to reach the water content of 10% through a plate frame, and then drying the iron powder in an indirect drying furnace at the temperature of 300 ℃ for 60min, wherein the total iron in the metal iron powder is over 93.8%.

(5) Washing the titanium slag subjected to magnetic separation with water, dehydrating the titanium slag with a plate frame until the water content is 12%, and drying the titanium slag in a roller for 40min at the smoke temperature of 400 ℃ to obtain TiO in the high-titanium slag powder₂ 92.1％。

TABLE 4 Main component/wt% of ilmenite concentrates

T.Fe	FeO	TiO₂	SiO₂	CaO	MgO	Al₂O₃
							32.39	36.5	47.15	3.1	0.05	0.1	0.21

TABLE 5 coal fines principal component/wt.%

Fixed carbon	Volatile matter	Ash content	S
				56.00％	30.00％	6.50％	0.42％

Example 4

the ilmenite concentrate powder used in this example had an average particle size of 325 to 625 mesh, and the main components are shown in table 6. The reducing agent is coal powder, the components of the coal powder are shown in Table 7, and the purity of the sodium carbonate is more than 95 percent. The granularity of the coal powder and the sodium carbonate is less than 100 meshes.

(1) Ferrotitanium concentrate powder, coal powder and sodium carbonate powder are mixed according to the mass ratio of 100: 12: 7, blending and uniformly mixing;

TABLE 6 Main component/wt% of ilmenite concentrates

T.Fe	FeO	TiO₂	SiO₂	CaO	MgO	Al₂O₃
							32.75	40.5	48.22	3.3	0.05	0.1	0.21

TABLE 7 coal fines principal component/wt.%

Fixed carbon	Volatile matter	Ash content	S
				79.29％	11.55％	8.50％	0.35％

Comparative example 1

The comparative example provides a method for preparing high-titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature, and the process flow is the same as that in example 1. The specific details are as follows:

the ilmenite concentrate powder used in this comparative example had a particle size of less than 100 mesh. The main components are shown in Table 1. The reducing agent is coal powder, the components of the coal powder are shown in table 2, and the purity of the sodium carbonate is more than 95 percent. The particle size of the coal powder and the sodium carbonate passes through 100 meshes.

(2) the mixture enters an indirect heating reduction device for heating reduction, the maximum temperature in the furnace is 920 ℃, the reaction time is 60min, the material thickness is 40mm, and the reduction rate of iron in the reduced ilmenite is 85%. Wherein, the indirect heating reduction device is a steel belt type heating furnace.

(4) And (3) carrying out filter pressing dehydration on the iron powder subjected to magnetic separation through a plate frame until the water content is 10%, and then drying the iron powder in an indirect drying furnace at the temperature of 300 ℃ for 60min, wherein the total iron in the metal iron powder is over 82.3%.

(5) Washing the titanium slag subjected to magnetic separation with water, dehydrating the titanium slag with a plate frame until the water content is 12%, and drying the titanium slag in a roller for 40min at the smoke temperature of 400 ℃ to obtain TiO in the high-titanium slag powder₂ 72.5％。

Comparative example 2

the ilmenite concentrate powder used in this comparative example had a particle size of less than 200 mesh. The main components are shown in Table 1. The reducing agent is coal powder, the components of the coal powder are shown in table 2, and the purity of the sodium carbonate is more than 95 percent. The particle size of the coal powder and the sodium carbonate passes through 100 meshes.

(2) the mixture enters an indirect heating reduction device for heating reduction, the maximum temperature in the furnace is 1150 ℃, the reaction time is 40min, the material thickness is 70mm, and the reduction rate of iron in the reduced ilmenite is 78%. Wherein, the indirect heating reduction device is a steel belt type heating furnace.

(4) And (3) carrying out filter pressing dehydration on the iron powder subjected to magnetic separation through a plate frame until the water content is 10%, and then drying the iron powder in an indirect drying furnace at the temperature of 300 ℃ for 60min, wherein the total iron in the metal iron powder is over 80.4%.

(5) Washing the titanium slag subjected to magnetic separation with water, dehydrating the titanium slag with a plate frame until the water content is 12%, and drying the titanium slag in a roller for 40min at the smoke temperature of 400 ℃ to obtain TiO in the high-titanium slag powder₂ 71.4％。

In the above examples 1-4, the amount of the coal powder obtained from 1 ton of the high-quality high-titanium slag is 150-280 kg (related to the coal type), and the power consumption is 200 kWh; the coal consumption is equivalent to the electric furnace smelting process, and the power consumption is far lower than that of the existing electric furnace smelting process of 2000-. Therefore, the method disclosed by the invention has the advantages that the high-titanium slag powder and the metal iron powder with high quality are produced with low coal consumption, low power consumption and low carbon emission, the green high-added-value utilization of the ilmenite concentrate powder is realized, and the economic benefit is obvious.

In the above comparative examples 1-2, the reduction temperature, the reduction time, the distribution thickness, and the ore powder particle size were all different, resulting in a large difference in the reduction effect. In the comparative example 1, the reduction temperature is 920 ℃, the reduction time is 60min, the granularity of the mineral powder is less than 100 meshes, the temperature is lower than the protection range of the invention, the reduction rate is reduced, and the reduction effect is poor due to the reduction time shortening and the coarsening of the granularity, so that the final separated product has poor quality. In the comparative example 2, the reduction temperature is 1150 ℃, the reduction time is 40min, the granularity of the ore powder is less than 200 meshes, the temperature is higher than the protection range of the invention, the reduction rate is relatively high, but the reduction effect is poor due to the reduction time shortening and the coarsening of the granularity, so that the final separated product has poor quality.

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 high titanium slag powder and metal iron powder by reducing ilmenite concentrate powder at low temperature is characterized by comprising the following steps:

2. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder of claim 1, wherein in step S1, the mass percent of CaO is less than 0.5% and the mass percent of MgO is less than 1%.

3. The method for preparing high-titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder according to claim 1, wherein in step S1, the mass ratio of ilmenite concentrate powder, powdered reducing agent, powdered sodium carbonate and/or sodium bicarbonate is 100: 10-20: 0 to 10.

4. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder of claim 1, wherein in step S1, the average particle size of the powdery reducing agent, the powdery sodium carbonate and/or the powdery sodium bicarbonate is smaller than 100 mesh.

5. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder as claimed in claim 1, wherein in step S2, the thickness of the material is controlled not to exceed 60 mm.

6. The method for preparing high-titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder as claimed in claim 1, wherein in step S2, the indirect heating reduction device is a steel belt type heating furnace or a pusher furnace.

7. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder as claimed in claim 6, wherein in step S2, the indirect heating reduction device can be gas heating, resistance wire heating or microwave heating.

8. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder as claimed in claim 1, wherein in step S2, the particle size of metallic iron in the reduced metallization mixture is more than 0.1 mm.

9. The method for preparing high titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder as claimed in claim 1, wherein in step S3, a wet magnetic separator is selected for magnetic separation.

10. The method for preparing high-titanium slag powder and metallic iron powder by low-temperature reduction of ilmenite concentrate powder according to claims 1-9, wherein the step S1 further includes: