CN106834775B - A kind of method of carbon thermal reduction and Nitration synthesis ferrovanadium nitride - Google Patents

Abstract

A method for synthesizing ferrovanadium nitride by carbothermal reduction and nitriding. According to different components, it is divided into three grades: FeV45N10, FeV55N11, and FeV65N13. The FeV45N10 product contains 43-49% of vanadium and 10-13% of nitrogen, and the product of FeV55N11 It contains 53‑58% vanadium and 11‑14% nitrogen. The FeV65N13 product contains 63‑69% vanadium and 12‑15% nitrogen. Reach 5.0-6.5g/cm ³ . The present invention directly uses vanadium oxides, iron oxides or iron simple substances, binders and carbonaceous reducing agents as main raw materials. After the raw materials are mixed and evenly mixed, they are briquetted and then put into a pusher kiln. Protected by a nitrogen atmosphere, it enters the pre-reduction zone, the medium-temperature carbothermal reduction and nitriding zone, the high-temperature sintering zone and the cooling zone in sequence to obtain the final ferrovanadium nitride. The product synthesized by the invention has good compactness and uniform nitrogen content. Compared with the traditional process of preparing ferrovanadium nitride with ferrovanadium, this product uses vanadium oxide as raw material to directly prepare ferrovanadium nitride, which can greatly reduce the process and cost; The wear rate is low and the loss is small.

Description

A method for carbothermal reduction and nitriding to synthesize ferrovanadium nitride

technical field

The invention belongs to the field of ferroalloy preparation, and in particular relates to ferrovanadium nitride and a preparation method thereof.

Background technique

my country is a country rich in vanadium resources, with abundant vanadium-bearing shale resources, and its total reserves rank first in the world. With the rapid development of my country's iron and steel industry, the demand for high-quality steel is also increasing. As an important alloy additive for high-strength micro-alloyed steel, the demand for ferrovanadium nitride is also increasing. Ferrovanadium nitride can effectively use nitrogen to optimize the precipitation state of vanadium, enhance the effect of precipitation strengthening and fine-grain strengthening, and therefore optimize the performance of steel. Current studies have found that adding ferrovanadium nitride alloys to steel can improve the strength, toughness, wear resistance, corrosion resistance and thermal fatigue resistance of steel, and make steel have excellent weldability. Compared with ferro-vanadium alloy and vanadium nitride, ferro-vanadium nitride can improve the utilization and recovery rate of vanadium, reduce the amount of vanadium added by about 30%, and greatly reduce the cost of high-strength micro-alloyed steel.

At present, the main methods of producing ferrovanadium nitride are solid state nitriding method, liquid state nitriding method and combustion synthesis method. The first two methods use vanadium-iron alloy as raw material, and nitrogen gas is introduced under a certain temperature and pressure for nitriding reaction, but the reaction time of this method is too long, the amount of nitriding is low, and the energy consumption is too large, resulting in the production of vanadium nitride. The iron process is complicated and the cost is too high, which increases the cost of producing high-strength steel grades. The production of ferrovanadium nitride by combustion synthesis method is to crush ferrovanadium and place it in a closed high-pressure container, and then introduce high-pressure nitrogen gas, and use the heat released by ferrovanadium nitride to nitride ferrovanadium powder, without the need to supplement energy from the outside . The product is cooled in nitrogen, and a dense block product with a nitrogen content of 8-12% can be obtained. However, this process is also based on ferrovanadium as a raw material, and the cost is naturally not low.

Contents of the invention

The purpose of the present invention is to directly prepare ferrovanadium nitride by using vanadium oxide as raw material, so as to greatly reduce the process flow and cost.

A method for carbothermal reduction and nitriding to synthesize ferrovanadium iron nitride, which is characterized in that the oxides of vanadium, iron oxides or iron, binding agent and carbonaceous reducing agent are used as main raw materials, and the above-mentioned raw materials are After mixing, mix it evenly, briquette it, and then put it into a pusher kiln filled with nitrogen atmosphere for high-temperature carbothermal reduction and nitriding reaction to prepare the ferrovanadium nitride, and the synthesized ferrovanadium nitride Divided into 3 grades; FeV45N10 ferrovanadium nitride includes vanadium 43-49%, nitrogen 11-13%, carbon 0-1%, oxygen 0-1%, the balance is Fe; FeV55N11 vanadium nitride contains vanadium 53-58 %, nitrogen 11-14%, carbon 0-1%, oxygen 0-1%, the balance is Fe; FeV65N13 iron vanadium nitride contains vanadium 63-69%, nitrogen 12-15%, carbon 0-1% , Oxygen 0-1%, the balance is Fe. The product is dense block, with a density of 5.0-6.5g/cm ³ , high strength, and the content of other impurities can be controlled at an extremely low level. In addition, since the method directly uses vanadium oxide as a raw material and skips the production process of preparing ferrovanadium, the production time of ferrovanadium nitride can be greatly shortened, production cost can be reduced, and production efficiency can be improved. The CO gas generated during the production process of this process can be used for power generation or heating to realize the secondary utilization of energy.

The present invention is achieved through the following technical solutions:

A method for synthesizing ferrovanadium nitride by carbothermal reduction and nitriding, the present invention uses vanadium oxide, iron element or its oxide, binder and carbonaceous reducing agent as main raw materials, after mixing the above raw materials , mix it, briquette it, then put it into the pusher kiln, pass through the nitrogen atmosphere, and go through the pre-reduction zone of the pusher kiln, the medium-temperature carbon thermal reduction and nitriding zone, the high-temperature sintering zone and the cooling zone. In four regions, the ferrovanadium nitride is prepared.

Further, the raw materials for preparing ferrovanadium nitride are only vanadium oxide, iron element or its oxide, binder and carbonaceous reducing agent, and no other raw materials that affect product quality are added. Vanadium oxides include V ₂ O ₃ , V ₂ O ₅ and VO, ammonium metavanadate and ammonium polyvanadate; iron oxides include FeO, Fe ₂ O ₃ and Fe ₃ O ₄ ; carbonaceous reducing agents include Graphite, carbon black, activated carbon, petroleum coke, coke and other carbon-containing reducing agents; binders include flour, polyvinyl alcohol, starch, cellulose, syrup, etc.

Further, the specific steps of the method for preparing ferrovanadium nitride include: the steps of raw material preparation, mixing and briquetting, and high-temperature reaction in a pusher kiln.

Further, the method for preparing ferrovanadium nitride is specifically: using vanadium oxides, iron oxides, and carbonaceous reducing agents as main raw materials, mixing the above-mentioned raw materials in a certain proportion, and mixing them evenly, The briquette is formed under a pressure of 10-50 MP, and then put into a pusher kiln, and a nitrogen atmosphere is passed through, and the ferrovanadium nitride is prepared through four reaction areas of the equipment. The temperature of each zone is 500-650°C, 650-1500°C, 1500-1600°C and 50-200°C respectively, and the corresponding time is 1h, 3h, 2h, 1h respectively. .

Further, the reaction process for preparing ferrovanadium nitride is as follows: firstly, the reactants are subjected to pre-reduction treatment at a low temperature stage, and the reactants are reduced to low-valent vanadium oxides to prevent volatilization loss of V ₂ O ₅ , and then in the medium temperature region The carbon direct reduction reaction is the main one, and the nitriding reaction is carried out simultaneously. Secondly, in the high-temperature stage, the sintering reaction is mainly used to deepen the deoxidation reaction, increase the nitrogen content of the product, further deoxidize and decarburize, and improve product quality.

Beneficial technical effect of the present invention:

(1) Carbothermal reduction and nitriding synthesis of ferrovanadium nitride is carried out under normal pressure, which requires low equipment requirements, low investment, and small plant area.

(2) This process uses vanadium oxides as raw materials to directly synthesize ferrovanadium nitride, which saves the current process of preparing vanadium-iron alloys with vanadium oxides, and the carbothermal reaction and nitriding reaction are fast, which greatly shortens the production cycle. Energy, equipment, and raw materials greatly reduce production costs.

(3) The ferrovanadium nitride obtained by this synthesis process has high density and high specificity, up to 5-6.5g/cm ³ , and the nitrogen content is evenly distributed. The composition of FeV45N10 contains 43-49% of vanadium and 11-13% of nitrogen. , carbon 0-1%, oxygen 0-1%, the rest is Fe, FeV55N11 products contain vanadium 53-58%, nitrogen 11-14%, carbon 0-1%, oxygen 0-1%, FeV65N13 products contain Vanadium 63-69%, nitrogen 12-15%, carbon 0-1%, oxygen 0-1%. There is no strict requirement on the oxygen content in the national standard, but the oxygen content has an important impact on the product quality. If the oxygen content is too high, the yield of vanadium will be reduced, and the added vanadium will partly enter the slag.

(4) This process mainly uses vanadium oxide as raw material, which has high purity and reduces the impurities brought in during the production process. The content of P, S, Si, Al, and Mn in the product is at an extremely low level.

(5) The specific gravity of this product is close to that of molten steel and is easily soluble in molten steel, which improves the absorption rate of vanadium and nitrogen in molten steel, promotes the strengthening effect of nitrogen on alloying elements on steel, and can also save the addition of vanadium to reduce production costs.

(6) The ferrovanadium nitride obtained by the synthesis process has high strength and is not broken during transportation and use.

(7) The synthesis process uses the pusher kiln equipment, fully utilizes the advantages of the equipment, and the reaction is divided into four temperature zones, fully carbothermal reduction reduces the oxygen content in the product, thereby increasing the nitrogen content of the product.

(8) During the production process of this process, CO gas will be generated, which can be used for heating or power generation, so as to realize the secondary utilization of energy.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention is further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

On the contrary, the invention covers any alternatives, modifications, equivalent methods and schemes within the spirit and scope of the invention as defined by the claims. Further, in order to make the public have a better understanding of the present invention, some specific details are described in detail in the detailed description of the present invention below. The present invention can be fully understood by those skilled in the art without the description of these detailed parts.

Example 1

The present invention uses V ₂ O ₅ , Fe ₂ O ₃ and activated carbon as raw materials, mixes them evenly, briquettes them, puts them into a pusher kiln filled with nitrogen atmosphere, first pushes the block sample to a pre-reduction area at 650°C, and keeps it warm for 2 hours , and then pushed to the 1400°C medium-temperature carbothermal reduction area, kept for 3 hours, then pushed to the 1600°C high-temperature sintering area for 2 hours, and finally the sample was pushed to the cooling area for cooling. The nitrogen content in the FeV45N10 ferrovanadium nitride obtained in this embodiment is 12.08%, and the carbon content is 0.67%. Table 1 compares the composition of this process product with the national standard and the vanadium-nitrogen alloy Nitrovan12 promoted by the US Strategic Minerals Company in China. We can see from the table that this product has higher nitrogen content on the basis of lower vanadium content, and the cost is much lower than that of American companies, and the carbon content is controlled at a lower level. Since this product uses high-purity vanadium oxide as raw material, the content of Si, Al, P, S and other elements is very low, reaching the national premium standard.

Table I

Example 2

The present invention uses V ₂ O ₃ , Fe and graphite as raw materials, mixes them evenly, briquettes them, puts them into a pusher kiln, and fills them with a nitrogen atmosphere. First, the block sample is pushed to a pre-reduction area at 600°C, kept for 2 hours, and then pushed To the 1300°C medium-temperature carbothermal reduction area, keep it warm for 3 hours, then push it to the 1500°C high-temperature sintering area for 1 hour, and finally push the sample to the cooling area for cooling. The nitrogen content in the FeV55N11 iron vanadium nitride obtained in this embodiment is 13.47%, and the carbon content is 0.23%.

Example 3

The present invention uses NH ₄ VO ₃ , Fe ₂ O ₃ and graphite as raw materials, mixes them evenly, briquettes them, puts them into a pusher kiln filled with nitrogen atmosphere, first pushes the block sample to a 450°C pre-reduction area, and keeps it warm for 2 hours , then pushed to the 1200°C medium-temperature carbothermal reduction area, held for 3 hours, then pushed to the 1550°C high-temperature sintering area for 2 hours, and finally pushed to the cooling area for cooling. The nitrogen content in the FeV65N13 iron vanadium nitride obtained in this embodiment is 14.2%, and the carbon content is 0.36.

Claims (3)

1. a method for carbothermal reduction and nitriding to synthesize ferrovanadium nitride, is characterized in that with the oxide compound of vanadium or vanadate, iron oxide compound, bonding agent and carbonaceous reductant as main raw material, the above After the raw materials are mixed, they are mixed evenly and formed into briquettes, and then put into a pusher kiln filled with nitrogen atmosphere to carry out high-temperature carbothermal reduction and nitriding reactions to prepare the ferrovanadium nitride, and the synthesized nitrogen Ferrovanadium is divided into 3 grades; FeV45N10 ferrovanadium nitride includes vanadium 43-49%, nitrogen 11-13%, carbon 0-1%, oxygen 0-1%, and the balance is Fe; FeV55N11 vanadium nitride contains vanadium 53-58%, containing nitrogen 11-14%, carbon 0-1%, oxygen 0-1%, the balance is Fe; FeV65N13 ferrovanadium nitride contains vanadium 63-69%, nitrogen 12-15%, carbon 0 -1%, oxygen 0-1%, the balance is Fe; The product is a dense block with a density of 5.0-6.5g/cm ³ ; The vanadium oxides are V ₂ O ₃ , V ₂ O ₅ , VO ₂ , VO; the vanadate is ammonium metavanadate and ammonium polyvanadate; The oxides of iron are FeO, Fe ₂ O ₃ and Fe ₃ O ₄ ; in the industrial production process, scrap steel and iron scale are directly used as raw materials; The specific steps include: raw material preparation, mixing, briquetting and high-temperature reaction steps in a pusher kiln; the synthetic equipment used is a pusher kiln, which is filled with nitrogen, and the mixed raw materials are continuously transported to a closed warehouse for reaction. The reaction is It is carried out under normal pressure; the pusher kiln is divided into four areas, namely, pre-reduction area, medium-temperature carbothermal reduction and nitriding area, high-temperature sintering area and cooling area; the temperature of each area is 500-650 ° C , 650-1500°C, 1500-1600°C and 50-200°C, the corresponding times are 1h, 3h, 2h, 1h respectively. 2. a kind of carbothermal reduction according to claim 1 and the method for nitriding synthetic iron vanadium nitride are characterized in that: carbonaceous reducing agent comprises graphite, carbon black, gac, petroleum coke, coke. 3. a kind of carbothermal reduction according to claim 1 and the method for nitriding synthetic iron vanadium nitride are characterized in that: binding agent comprises flour, polyvinyl alcohol, starch, cellulose, syrup.