Vanadium titano-magnetite iron coke as well as preparation method and application thereof

Abstract

The invention belongs to the field of ferrous metallurgy, and particularly relates to vanadium titano-magnetite iron coke as well as a preparation method and application thereof. The vanadium titano-magnetite ferrocoke provided by the invention is prepared from a mixture of vanadium titano-magnetite powder and pulverized coal through hot press molding and anaerobic carbonization. The vanadium titano-magnetite ferrocoke provided by the invention can be positioned between a slag layer and a molten iron layer when being applied to an electric furnace deep reduction process, so that energy conservation and emission reduction are facilitated, the deep reduction time is shortened, and the carbon content and the vanadium recovery rate of deeply reduced molten iron are improved.

Description

Technical Field

[0001] The invention belongs to the field of iron and steel metallurgy, and in particular relates to a vanadium-titanium magnetite iron coke and a preparation method and application thereof. Background Art

[0002] Under the current background, developing non-blast furnace ironmaking technology in order to deeply reduce carbon is a major direction of the development of ironmaking technology. Vanadium-titanium magnetite, as a complex co-existing ore of iron, vanadium and titanium, needs to be comprehensively recycled and utilized for its three valuable elements. Regardless of the method used in the previous process to produce metallized pellets, deep reduction is required during the electric furnace smelting process to allow the vanadium element to be present in the molten iron for subsequent vanadium extraction.

[0003] The deep reduction process of vanadium-titanium ore metallized pellets needs to go through the process of submerged arc smelting-gradual lifting of electrodes-open arc smelting. The final open arc smelting is mainly the process of deep reduction of vanadium into molten iron. At this time, the separation of slag and iron is basically completed, the added coke is distributed above the slag layer, and the molten iron is below the slag layer. The heat source is mainly the thermal radiation of the electric arc. It is difficult for the molten iron to obtain enough heat. The thermodynamic conditions of the reaction between carbon in the molten iron and the vanadium oxide in the slag are worse than those between coke and the vanadium oxide in the slag. The contact area of ​​the liquid-solid reaction between coke and the slag layer is small, and the reaction rate is limited. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a vanadium-titanium magnetite iron coke and a preparation method and application thereof. The vanadium-titanium magnetite iron coke provided by the present invention can be located between the slag layer and the molten iron layer when applied to the electric furnace deep reduction process, which is beneficial to energy conservation and emission reduction, shortening the deep reduction time, and increasing the carbon content of the deep reduced molten iron and the vanadium recovery rate.

[0005] The invention provides a vanadium-titanium magnetite iron coke, which is prepared by hot pressing and oxygen-free carbonization of a mixture of vanadium-titanium magnetite powder and coal powder.

[0006] Preferably, the content of the vanadium-titanium magnetite powder in the mixture is 50-70wt%.

[0007] Preferably, the vanadium-titanium magnetite iron coke has a TFe content of 34-37wt%, an MFe content of 27-32wt%, an FeO content of 7-9wt%, and a C content of 40-45wt%.

[0008] Preferably, the density of the vanadium-titanium magnetite iron coke is 3.2-3.4 g / cm 3 .

[0009] The present invention provides a method for preparing vanadium-titanium magnetite iron coke described in the above technical solution, comprising the following steps:

[0010] Mixing vanadium-titanium magnetite powder with coal powder to obtain a mixture;

[0011] Hot pressing the mixed material to obtain a preform;

[0012] The blank is subjected to oxygen-free carbonization to obtain vanadium-titanium magnetite iron coke.

[0013] Preferably, the pressure of the hot pressing molding is 3 to 3.5 t / cm 2 , the temperature is 200-230℃.

[0014] Preferably, the temperature of the oxygen-free carbonization is 980-1030° C., and the time is 2-3 hours.

[0015] The present invention provides a process for deep reduction in an electric furnace, comprising the following steps:

[0016] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag;

[0017] The reducing agent is the vanadium-titanium magnetite iron coke described in the above technical solution or the vanadium-titanium magnetite iron coke prepared by the preparation method described in the above technical solution.

[0018] Preferably, the mass ratio of the metallized pellets to the reducing agent is 100:(30-45).

[0019] Preferably, the raw material for preparing the metallized pellets is vanadium-titanium magnetite.

[0020] Compared with the prior art, the present invention provides a vanadium-titanium magnetite iron coke and a preparation method and application thereof. The vanadium-titanium magnetite iron coke provided by the present invention is made by hot pressing and oxygen-free carbonization of a mixture of vanadium-titanium magnetite powder and coal powder. The present invention uses vanadium-titanium magnetite and coal to produce iron coke. Since the cold and hot strength of iron coke during deep reduction in an electric furnace is not as strict as that of a blast furnace, the proportion of vanadium-titanium magnetite can be increased to increase the density of iron coke, and the reactivity of iron coke can also be improved, so that the iron coke can be located between the slag layer and the molten iron layer during the deep reduction process, and does not affect the contact between the molten iron and the slag layer, which is not only conducive to increasing the temperature of the molten iron and the carbon content in the molten iron, but also strengthens the reaction temperature of carbon and oxide in the molten iron without affecting the reduction reaction of vanadium oxide in the coke and slag, and strengthens the kinetic conditions of this reaction, and finally achieves the advantages of improving the distribution of carbonaceous reducing agents, shortening the deep reduction time, increasing the vanadium recovery rate and increasing the carbon content of molten iron, making the molten iron easier to transport, etc. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] The invention provides a vanadium-titanium magnetite iron coke, which is prepared by hot pressing and oxygen-free carbonization of a mixture of vanadium-titanium magnetite powder and coal powder.

[0023] In the vanadium-titanium magnetite ferrocoke provided by the present invention, the TFe content of the vanadium-titanium magnetite powder is preferably 50-60wt%, specifically 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt% or 60wt%; the proportion of particles smaller than 200 mesh size in the vanadium-titanium magnetite powder is preferably ≥70wt%, more preferably ≥80wt%.

[0024] In the vanadium-titanium magnetite iron coke provided by the present invention, the carbon content of the coal powder is preferably 60-90wt%, specifically 60wt%, 62wt%, 65wt%, 67wt%, 70wt%, 72wt%, 75wt%, 78wt%, 80wt%, 82wt%, 85wt%, 87wt% or 90wt%; the proportion of particles smaller than 200 mesh size in the coal powder is preferably ≥60wt%, more preferably ≥70wt%.

[0025] In the vanadium-titanium magnetite iron coke provided by the present invention, the content of the vanadium-titanium magnetite powder in the mixture is preferably 50-70wt%, specifically 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt% or 70wt%.

[0026] In the vanadium-titanium magnetite iron coke provided by the present invention, the pressure of the hot pressing molding is preferably 3-3.5 t / cm 2 , specifically 3t / cm 2 、3.05t / cm 2 、3.1t / cm 2 、3.15t / cm 2 、3.2t / cm 2 、3.25t / cm 2 、3.3t / cm 2 、3.35t / cm 2、3.4t / cm 2 、3.45t / cm 2 or 3.5t / cm 2 The temperature of the hot pressing molding is preferably 200-230°C, specifically 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C.

[0027] In the vanadium-titanium magnetite iron coke provided by the present invention, the oxygen-free carbonization is preferably carried out in an inert atmosphere; the temperature of the oxygen-free carbonization is preferably 980-1030°C, specifically 980°C, 985°C, 990°C, 995°C, 1000°C, 1005°C, 1010°C, 1015°C, 1020°C, 1025°C or 1030°C; the time of the oxygen-free carbonization is preferably 2-3h, specifically 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h.

[0028] In the vanadium-titanium magnetite iron coke provided by the present invention, the TFe (total iron) content of the vanadium-titanium magnetite iron coke is preferably 34-37wt%, specifically 34wt%, 34.5wt%, 35wt%, 35.5wt%, 36wt%, 36.5wt% or 37wt%; the MFe (magnetic iron) content of the vanadium-titanium magnetite iron coke is preferably 27-32wt%, specifically 27wt%, 27.5wt%, 28wt%, 28.5wt%, 29wt%, 29.5wt%, 30wt%, 30.5wt%, 31wt%, 31.5wt% or 32wt%. % or 32wt%; the FeO (iron oxide) content of the vanadium-titanium magnetite iron coke is preferably 7-9wt%, specifically 7wt%, 7.2wt%, 7.5wt%, 7.8wt%, 8wt%, 8.2wt%, 8.5wt%, 8.7wt% or 9wt%; the C content of the vanadium-titanium magnetite iron coke is preferably 40-45wt%, specifically 40wt%, 40.5wt%, 41wt%, 41.5wt%, 42wt%, 42.5wt%, 43wt%, 43.5wt%, 44wt%, 44.5wt% or 45wt%.

[0029] In the vanadium-titanium magnetite iron coke provided by the present invention, the density of the vanadium-titanium magnetite iron coke is preferably 3.2-3.4 g / cm 3 , specifically 3.2g / cm 3 、3.23g / cm 3 , 3.25g / cm 3 、3.27g / cm 3 、3.3g / cm 3 、3.32g / cm 3 、3.35g / cm3 、3.37g / cm 3 or 3.4g / cm 3 .

[0030] The present invention also provides a method for preparing the vanadium-titanium magnetite iron coke described in the above technical solution, comprising the following steps:

[0031] Mixing vanadium-titanium magnetite powder with coal powder to obtain a mixture;

[0032] Hot pressing the mixed material to obtain a preform;

[0033] The blank is subjected to oxygen-free carbonization to obtain vanadium-titanium magnetite iron coke.

[0034] In the preparation method provided by the present invention, the content of the vanadium-titanium magnetite powder in the mixture is preferably 50-70wt%, specifically 50wt%, 51wt%, 52wt%, 53wt%, 54wt%, 55wt%, 56wt%, 57wt%, 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, 64wt%, 65wt%, 66wt%, 67wt%, 68wt%, 69wt% or 70wt%.

[0035] In the preparation method provided by the present invention, the pressure of the hot pressing molding is preferably 3 to 3.5 t / cm 2 , specifically 3t / cm 2 、3.05t / cm 2 、3.1t / cm 2 、3.15t / cm 2 、3.2t / cm 2 、3.25t / cm 2 、3.3t / cm 2 、3.35t / cm 2 、3.4t / cm 2 、3.45t / cm 2 or 3.5t / cm 2 ; The temperature of the hot pressing molding is preferably 200-230°C, specifically 200°C, 205°C, 210°C, 215°C, 220°C, 225°C or 230°C; The time of the hot pressing molding is preferably 10-30min, specifically 10min, 15min, 20min, 25min or 30min.

[0036] In the preparation method provided by the present invention, the anaerobic carbonization is preferably carried out in an inert atmosphere; the temperature of the anaerobic carbonization is preferably 980-1030°C, specifically 980°C, 985°C, 990°C, 995°C, 1000°C, 1005°C, 1010°C, 1015°C, 1020°C, 1025°C or 1030°C; the time of the anaerobic carbonization is preferably 2-3h, specifically 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h, 2.6h, 2.7h, 2.8h, 2.9h or 3h.

[0037] The present invention provides a process for deep reduction in an electric furnace, comprising the following steps:

[0038] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag;

[0039] The reducing agent is the vanadium-titanium magnetite iron coke described in the above technical solution or the vanadium-titanium magnetite iron coke prepared by the preparation method described in the above technical solution.

[0040] In the process provided by the present invention, the metallized pellets are preferably prepared according to the following steps: iron concentrate is used to produce oxidized pellets in a rotary kiln, and the oxidized pellets are reduced in a gas-based vertical furnace to become metallized pellets. In the present invention, the iron concentrate used to prepare the metallized pellets is preferably vanadium-titanium magnetite, and more preferably vanadium-titanium magnetite having the same composition as the vanadium-titanium magnetite powder used to prepare the vanadium-titanium magnetite iron coke.

[0041] In the process method provided by the present invention, the mass ratio of the metallized pellets to the reducing agent is preferably 100:(30-45), specifically 100:30, 100:31, 100:32, 100:33, 100:34, 100:35, 100:36, 100:37, 100:38, 100:39, 100:40, 100:41, 100:42, 100:43, 100:44 or 100:45.

[0042] In the process method provided by the present invention, the temperature for melting and deep reducing the metallized pellets in the electric furnace is preferably 1400-1800°C, specifically 1400°C, 1450°C, 1500°C, 1550°C, 1600°C, 1650°C, 1700°C, 1750°C or 1800°C; the time for melting and deep reducing the metallized pellets in the electric furnace is preferably 2-5h, specifically 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.

[0043] The technical solution provided by the present invention is mainly aimed at the deep reduction process in the electric furnace in the non-blast furnace ironmaking process of the gas-based vertical furnace-electric furnace for smelting vanadium-titanium magnetite pellets. Generally, iron ore concentrate is used to produce oxidized pellets in a rotary kiln, and the oxidized pellets are reduced in the gas-based vertical furnace to become metallized pellets. The metallized pellets need to be melted and further reduced in the electric furnace (divided into deep reduction and shallow reduction, the main difference being that more carbonaceous reducing agents are needed in the deep reduction process to reduce the vanadium element to the molten iron). During the deep reduction process of the electric furnace, the metallized pellets and gangue components (mainly entering the slag) will melt as the temperature rises. Generally, the molten iron has a high specific gravity and is mostly in the lower layer of the molten pool. The slag is above the molten iron. The coke has the lightest specific gravity and floats on the uppermost layer, which results in less contact between the molten iron and the coke. The coke is also oxidized by air in the upper layer, which increases the consumption. The iron coke provided by the present invention has a specific gravity greater than the slag and is lighter than the molten iron. In this way, the iron coke is at the slag-iron interface layer, which increases its contact area with the slag and iron. The slag in the upper layer can also isolate the air and heat preservation to a certain extent, reduce the carbon consumption, and increase the temperature of the molten pool. At the same time, the kinetic conditions are also improved, which is conducive to the carbon in the iron coke to reduce vanadium pentoxide and enter the molten iron. The ore powder in the iron coke is used as the raw material of the oxidized pellets, and other impurities will not be brought into the process. In addition, the increase in the temperature of the molten iron will allow it to dissolve more carbon elements, so the carbon content in the molten iron increases.

[0044] For the purpose of greater clarity, the present invention is described in detail with reference to the following examples and comparative examples.

[0045] Example 1

[0046] (1) Preparation of vanadium-titanium magnetite iron coke:

[0047] Use dried vanadium-titanium magnetite powder (TFe content 53-57wt%, less than 200 mesh size ratio ≥80wt%) and coal powder (carbon content 70-80wt%, less than 200 mesh size ratio ≥70wt%) to mix evenly (the mass ratio of vanadium-titanium magnetite to coal powder is 50-70%:30-50%), place the mixed raw materials in a hot pressing mold and heat at a temperature of 210°C and a pressure of 3.2t / cm 2 The hot pressed sample was then carbonized at 1000°C in an inert atmosphere for 2.5 hours to obtain ferrocoke for deep reduction in an electric furnace.

[0048] The composition characteristics of this ferrocoke are: TFe content is 34-37wt%, MFe content is 27-32wt%, FeO content is 7-9wt%, and C content is 40-45wt%. Due to the high iron content, the density of this ferrocoke can reach 3.2-3.4g / cm 3 , greater than 2.9-3.0g / cm of molten slag 3 The density of the ore allows it to be distributed between the slag layers.

[0049] (2) Preparation of metallized pellets:

[0050] The vanadium-titanium magnetite ore with the same composition as the vanadium-titanium magnetite powder used for preparing iron coke is added into the rotary kiln to produce oxidized pellets, and the oxidized pellets are reduced in the gas-based vertical furnace to become metallized pellets.

[0051] (3) Electric furnace deep reduction process:

[0052] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag; wherein the reducing agent is the above-mentioned iron coke for deep reduction in an electric furnace, the mass ratio of the metallized pellets to the iron coke is 100:40, the temperature for melting and deep reduction of the metallized pellets in the electric furnace is 1600°C, and the reduction time is 3.5h. The composition of the molten iron and the recovery rate of vanadium are detailed in Table 1.

[0053] Example 2

[0054] Electric furnace deep reduction process:

[0055] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag; wherein the reducing agent used is the iron coke for deep reduction in an electric furnace prepared in Example 1, the metallized pellets used are consistent with those in Example 1, the mass ratio of the metallized pellets to the iron coke is 100:36, the temperature for melting and deep reduction of the metallized pellets in the electric furnace is 1600°C, and the reduction time is 3.5h. The composition of the molten iron and the recovery rate of vanadium are detailed in Table 1.

[0056] Example 3

[0057] Electric furnace deep reduction process:

[0058] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag; wherein the reducing agent used is the iron coke for deep reduction in an electric furnace prepared in Example 1, the metallized pellets used are consistent with those in Example 1, the mass ratio of the metallized pellets to the iron coke is 100:32, the temperature for melting and deep reduction of the metallized pellets in the electric furnace is 1600°C, and the reduction time is 3.5h. The composition of the molten iron and the recovery rate of vanadium are detailed in Table 1.

[0059] Comparative Example 1

[0060] Electric furnace deep reduction process:

[0061] In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag; wherein the reducing agent is coke (composition: about 85wt% C, 12-14wt% ash, 1-1.2wt% volatile matter, 0.6-0.9wt% S; true density: about 1.8-1.9g / cm 3), the metallized pellets used were consistent with those in Example 1, the mass ratio of the metallized pellets to the coke was 100:20, the temperature for melting and deep reduction of the metallized pellets in the electric furnace was 1600°C, and the reduction time was 4 hours. The molten iron composition and vanadium recovery rate are detailed in Table 1.

[0062] Table 1 Molten iron composition and vanadium recovery rate

[0063] name Fe / % V / ％ Ti / % C / ％ Si / % Vanadium recovery rate / % Example 1 95.18 0.586 0.235 3.5 0.195 84.76 Example 2 95.79 0.574 0.236 3.2 0.197 82.53 Example 3 96.09 0.567 0.237 2.9 0.197 81.32 Comparative Example 1 96.70 0.561 0.238 2.3 0.198 79.86

[0064] As can be seen from the above table, this method uses vanadium-titanium magnetite that is consistent with that used for metallized pelletized ore to prepare ferrocoke for the electric furnace deep reduction process, and then uses this ferrocoke to replace coke in the electric furnace deep reduction process. Without introducing other impurity raw materials, it achieves the goal of reducing carbon consumption in the deep reduction process, reducing the deep reduction time, increasing the vanadium yield by 1.46-4.9%, and increasing the carbon content in molten iron by 0.6-1.2%. It has the effects of improving vanadium yield, saving coal and reducing emissions, and improving the convenience of molten iron transportation, and has good application effects and promotion value.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A vanadium-titanium magnetite iron coke, characterized in that: It is made of a mixture of vanadium-titanium magnetite powder and coal powder through hot pressing and oxygen-free carbonization.

2. The vanadium-titanium magnetite iron coke according to claim 1, characterized in that: The content of the vanadium-titanium magnetite powder in the mixture is 50-70wt%.

3. The vanadium-titanium magnetite iron coke according to claim 1, characterized in that: The vanadium-titanium magnetite iron coke has a TFe content of 34-37wt%, an MFe content of 27-32wt%, a FeO content of 7-9wt%, and a C content of 40-45wt%.

4. The vanadium-titanium magnetite iron coke according to claim 1, characterized in that: The density of the vanadium-titanium magnetite iron coke is 3.2-3.4 g / cm 3 .

5. A method for preparing vanadium-titanium magnetite iron coke according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing vanadium-titanium magnetite powder with coal powder to obtain a mixture; Hot pressing the mixed material to obtain a preform; The blank is subjected to oxygen-free carbonization to obtain vanadium-titanium magnetite iron coke.

6. The preparation method according to claim 5, characterized in that: The pressure of the hot pressing molding is 3-3.5 t / cm 2 , the temperature is 200-230℃.

7. The preparation method according to claim 5, characterized in that: The temperature of the oxygen-free carbonization is 980-1030° C., and the time is 2-3 hours.

8. A process for deep reduction in an electric furnace, characterized in that: The following steps are involved: In the presence of a reducing agent, the metallized pellets are melted and deeply reduced in an electric furnace to generate molten iron and slag; The reducing agent is the vanadium-titanium magnetite iron coke as described in any one of claims 1 to 4 or the vanadium-titanium magnetite iron coke prepared by the preparation method as described in any one of claims 5 to 7.

9. The process according to claim 8, characterized in that: The mass ratio of the metallized pellets to the reducing agent is 100:(30-45).

10. The process according to claim 8, characterized in that: The raw material for preparing the metallized pellets is vanadium-titanium magnetite.