CN105087994A - Method for preparing high-nitrogen high-purity vanadium-nitrogen alloy - Google Patents

Abstract

The invention relates to a method for preparing a high-nitrogen high-purity vanadium-nitrogen alloy, which belongs to the technical field of metallurgy. The present invention utilizes self-propagating high-temperature synthesis technology; coarse-grade ammonium metavanadate is used as a raw material, hydrogen is directly passed through, and nitrogenation is promoted by NH ₄ ⁺ in NH ₄ VO ₃ , and nitriding is carried out at high temperature. In the synthesis process of the present invention, there is no The addition of other reducing or heating materials can greatly reduce the impurities in the product, and there is no discharge of three wastes, and the product quality is high. The product of the present invention is dense, with a specific gravity up to 6.5g/cm ³ , and the nitrogen content is evenly distributed. The S content of the vanadium nitrogen alloy is ≤0.1%, and the silicon content of the vanadium nitrogen alloy is ≤0.1%.

Description

A kind of method for preparing high-nitrogen high-purity vanadium-nitrogen alloy

technical field

The invention relates to a method for preparing a high-nitrogen high-purity vanadium-nitrogen alloy, which belongs to the technical field of metallurgy.

Background technique

my country is the world's largest steel producer and also the world's largest steel consumer. However, low-carbon structural steel is the most used steel, accounting for about 70% of the steel usage. Therefore, improving the strength of ordinary carbon steel is an important direction to promote the technological progress of my country's steel industry and adjust the steel structure. The solution is to increase alloyed steel - adding high nitrogen and high purity vanadium nitrogen alloy. Using vanadium-nitrogen alloying, no need to add other precious alloy elements, high-strength steel with a yield strength of 550-600Mpa can be obtained under general hot rolling conditions, so long products such as high-strength steel bars and steel plates (strips) , thick plate, thick-walled section steel, seamless steel pipe, CSP and other products have been widely used in the development.

In 1998, the US Strategic Minerals Corporation carried out the development of vanadium-nitrogen alloying technology and the promotion and application of its patented product vanadium-nitrogen alloy in my country's iron and steel industry. Some domestic steel mills carried out application tests in the production of HRB400 grade steel bars. Domestic research units and Some large steel mills have conducted a lot of research on the effect of adding vanadium-nitrogen alloy on the mechanical properties of steel and the strengthening mechanism. Better performance, more stable HRB400MpaIII grade threaded steel bar and V-N steel can be produced, and at the same time, 30-40% of vanadium can be saved, which greatly reduces the cost of steel. The United States claims that the United States is the only country that can commercially produce vanadium-nitrogen alloys, but this technology is not disclosed. Domestic enterprises have been able to mass-produce vanadium-nitrogen alloys after research and testing, but the current output of vanadium-nitrogen alloy products in my country cannot meet the needs of domestic production of high-strength steel bars and other steel products. Since 2003, we have used self-propagating high-temperature synthesis technology to develop and produce ferro-vanadium nitride, and have successfully applied it to the production of V-N steel in some large domestic steel plants.

Self-propagating high-temperature synthesis technology was discovered by the Institute of Chemical Physics of the former Soviet Academy of Sciences in 1967 when researching rocket solid fuels. The synthesis principle is to use a very small amount of energy provided by the outside to induce high heat release between heterogeneous substances in powder or powder compacts. Chemical reaction to form the combustion wave at the front of the reaction, and the subsequent synthesis reaction induces the continuous chemical reaction of adjacent materials with the support of self-exothermic self-sustained combustion until all the materials are reacted to synthesize the compound material with the required composition and structure. The advantages of self-propagating high-temperature synthesis technology are energy saving (the synthesis process does not require additional energy), high efficiency (the synthesis speed is extremely fast), environmental protection (no pollutants are discharged during the synthesis process), and high quality (stable composition and high purity). Self-propagating high-temperature synthesis technology is a high-tech in the current synthesis field. In the late 1980s, many units in our country carried out research in this area.

Self-propagating high-temperature synthesis does not require an external heat source during the synthesis process, so the focus of thermodynamic calculations is to discuss the possibility of its reaction, which is the basis for discussing the self-propagating high-temperature synthesis process, and the adiabatic combustion temperature of the synthesis reaction directly calculated according to the thermodynamic formula (Tad) is an important parameter to characterize combustion synthesis, which is of great significance to the theoretical research and application of self-propagating high-temperature synthesis. The most reliable method to predict the possibility of self-propagating high-temperature synthesis process is to calculate the adiabatic combustion temperature of a given mixed system, which is a qualitative basis for judging whether the combustion synthesis reaction can be self-sustaining. Merzhanov, the founder of the self-propagating high-temperature synthesis process, proposed some general empirical criteria ["Combustion Synthesis" 1999: P.56]: only when Tad>1800K, the self-propagating high-temperature synthesis reaction can be self-sustained. For the nitriding of vanadium metal or vanadium alloy raw materials, the adiabatic combustion temperature is mainly calculated through the reaction of vanadium and nitrogen. The adiabatic combustion temperature of the synthesis reaction of vanadium nitrogen compounds is 3500K, and even the adiabatic combustion temperature of vanadium iron raw materials is close to Merzhanov et al Put forward the requirement of Tad>1800K experience value. For example, on September 8, 2010, the Chinese Invention Patent Application Publication No. CN101824556A disclosed a method for producing ferrovanadium nitride using a self-propagating high-temperature synthesis process. The raw materials are ferrovanadium and nitrogen. Crushing, dry the crushed ferrovanadium raw materials and put them in bulk in a crucible, place the crucible in a high-pressure synthesizer and fill it with 6-12MPa nitrogen, start the ignition device to ignite the raw materials to carry out the synthesis reaction, and the combustion synthesis reaction is self-sustaining Carried out, the ferrovanadium nitride synthesized by combustion was taken out after being cooled in nitrogen, and broken into pieces. However, the nitrogen content in the synthetic product is only 9.0-17.0%, and there are problems such as low nitrogen content (≤17%) and high content of impurities such as carbon, sulfur and silicon, which seriously affect the nitrogen addition and performance of steel. Compared with ordinary low-nitrogen vanadium-nitrogen alloys, vanadium-nitrogen alloys with nitrogen content (≥17%) can more effectively promote the improvement of steel strength, toughness, ductility, fatigue resistance and other properties, and further reduce the use of vanadium to save costs. Reducing impurities such as carbon, sulfur and silicon in the vanadium-nitrogen alloy can reduce the excessive external impurities brought in when the vanadium-nitrogen alloy is added in steelmaking, which will affect the performance of the steel.

Contents of the invention

The technical problem to be solved by the present invention is: to propose a method for preparing high-nitrogen high-purity vanadium-nitrogen alloys, using crude-grade ammonium metavanadate directly as raw materials for vanadium-nitrogen alloys instead of using high-priced vanadium products such as ferrovanadium as raw materials, using self- The propagating low-temperature combustion reaction itself releases heat for nitriding, the reaction time is short, energy consumption and cost are low, and the produced nitrogen-vanadium alloy has high nitrogen and high purity, and the nitrogen content is ≥17%. Nitrogen content is better than American VN alloy.

According to the requirements proposed in the present invention, the technical scheme adopted in the present invention is:

A method for preparing high-nitrogen high-purity vanadium-nitrogen alloys, using self-propagating high-temperature synthesis technology; it is characterized in that coarse-grade ammonium metavanadate is used as raw material, hydrogen is directly passed through, and nitrogen synthesis is promoted by NH ₄ ⁺ in NH ₄ VO ₃ , nitriding at high temperature, NH ₄ VO ₃ +H ₂ =VN+3H ₂ O;

The specific steps are: first put the coarse-grade ammonium metavanadate into graphite crucibles respectively, then put these graphite crucibles into a stacked state and put them into an airtight container, and inject hydrogen gas from the bottom of the graphite crucible at the bottom; start the ignition The device ignites the raw materials for synthesis reaction, and burns and synthesizes high-nitrogen and high-purity vanadium-nitrogen alloy; H ₂ O is discharged from the top of the airtight synthesis container through the exhaust valve; when the vanadium nitriding reaction temperature reaches 1500°C-1520°C; adjust and control the exhaust The valve makes the water vapor pressure in the airtight synthesis container be 2-3Mpa, and the combustion synthesis reaction proceeds continuously; after the reaction is complete, the high-nitrogen and high-purity vanadium-nitrogen alloy is taken out in the graphite crucible after being cooled by nitrogen gas, and broken into pieces.

Innovation point and beneficial effect of the present invention are:

The present invention provides a new option for the production of high-nitrogen high-purity vanadium-nitrogen alloys. The present invention directly uses coarse-grade ammonium metavanadate as a raw material, directly passes hydrogen, and promotes nitrogen synthesis by NH ₄ ⁺ in NH ₄ VO ₃ , nitriding at high temperature; the present invention utilizes an exhaust valve to control the synthesis pressure in the airtight synthesis container to be 2-3Mpa, and the _H2O in the vanadium-nitrogen alloy is limited to be discharged during the synthesis process, which becomes slow and will not continuously flow from The surface of the vanadium-nitrogen alloy body gushes out from the same position to form air gaps, so the final product of the vanadium-nitrogen alloy of the present invention has fewer surface cracks, improves its surface quality, and thus improves its product quality.

Compared with the CN101824556A technique, the inventive method has the following advantages:

1. In the present invention, coarse-grade NH ₄ VO ₃ is directly used as raw material for vanadium-nitrogen alloy instead of high-priced vanadium products such as V ₂ O ₅ as raw material, and the source of raw material is easier to obtain; both NH ₄ ⁺ in NH ₄ VO ₃ can be used to promote Nitrogenation, and save a lot of cost;

2. No other reducing or heating materials are added in the synthesis process of the present invention, which can greatly reduce the impurities in the product, and there is no discharge of three wastes, and the product quality is high;

3. The present invention utilizes the self-propagating low-temperature combustion reaction to release heat itself to realize sufficient reaction of vanadium and nitrogen, thereby realizing high nitrogen content of the alloy and ensuring uniform and stable product quality. Moreover, the whole reaction synthesis process does not need electric heating and heat preservation, which saves energy and procedures, is easy to control, and is convenient for equipment processing and installation. Using the new technology of self-propagating low-temperature combustion can also make the synthesis cycle less than 50 minutes, which is much shorter than the reaction time of the existing technology, greatly improving production efficiency;

4. The present invention adopts an exhaust valve to control the synthesis pressure in the airtight synthesis container to control the surface air gap of the final product vanadium-nitrogen alloy; to make the product prepared by the combustion synthesis process stronger, and there is almost no breakage during material transportation and use, thereby Reduced material loss rate;

5. Combustion synthesis technology is adopted, no briquetting is required for either the initial synthesis charge or the final product. The synthetic product is dense, with a large specificity, up to 6.5g/cm ³ , and the nitrogen content is evenly distributed. The composition of the high-nitrogen high-purity vanadium-nitrogen alloy is: vanadium-nitrogen alloy containing V ≥ 78%, vanadium-nitrogen alloy containing N ≥ 17% %, vanadium nitrogen alloy C content ≤ 5%, vanadium nitrogen alloy S content ≤ 0.1%, vanadium nitrogen alloy silicon content ≤ 0.1%.

Detailed ways

A kind of method for preparing high-nitrogen high-purity vanadium-nitrogen alloy of the present invention:

A method for preparing high-nitrogen high-purity vanadium-nitrogen alloys, using self-propagating high-temperature synthesis technology, using coarse-grade ammonium metavanadate as raw material, directly passing hydrogen, and promoting nitrogen combination by NH ₄ ⁺ in NH ₄ VO ₃ , at high temperature Under nitriding;

NH ₄ VO ₃ +H ₂ =VN+3H ₂ O;

The present invention is a solid-gas reaction, which belongs to the type of "permeation combustion synthesis". Osmotic combustion synthesis is a process in which hydrogen infiltrates into NH ₄ VO ₃ and undergoes exothermic chemical transformation and structural transformation with nitrogen atoms; according to the current combustion synthesis process of NH ₄ VO ₃ , the nitrogen atoms contained in NH ₄ VO ₃ are sufficient to maintain vanadium nitrogen required for the chemical reaction;

The coarse-grade ammonium metavanadate of the present invention is loaded into graphite crucibles one by one respectively, and these graphite crucibles are put into a closed container in a stacked state, and hydrogen gas is introduced from the bottom of the graphite crucible in the lowest layer; the ignition device is started to ignite the raw materials Carry out synthesis reaction, burn and synthesize high-nitrogen and high-purity vanadium-nitrogen alloy; H ₂ O is discharged from the top of the airtight synthesis container through the exhaust valve; when the vanadium nitriding reaction temperature reaches 1500°C-1520°C; adjust and control the exhaust valve to make the airtight synthesis The water vapor pressure in the container is 2-3Mpa, and the combustion synthesis reaction is self-continuous; after the reaction is complete, the high-nitrogen high-purity vanadium-nitrogen alloy is cooled by nitrogen in the graphite crucible, taken out, and broken into pieces.

As mentioned above, the present invention provides a method for preparing high-nitrogen high-purity vanadium-nitrogen alloys, and an application for an invention patent is now filed according to law; however, the above description is one of the preferred embodiments of the present invention, and is not intended to limit the present invention , Therefore, all those that are similar to or identical to the features of the present invention should fall within the scope of the patent application of the present invention.

Claims (1)

1. prepare a method for the high-purity VN alloy of high nitrogen, utilize SHS technology; It is characterized in that with thick level ammonium meta-vanadate for raw material, directly logical hydrogen, by NH ₄vO ₃in NH ₄ ⁺promote that nitrogen closes, at high temperature nitriding; Concrete steps are: be first respectively charged into by thick level ammonium meta-vanadate one by one in plumbago crucible, then become laminated arrangement to put into airtight synthesising container these plumbago crucibles, pass into hydrogen from the bottom position of orlop plumbago crucible; The starting ignition device raw material that ignites carries out building-up reactions, the high-purity VN alloy of conbustion synthesis height nitrogen; H ₂o discharges from the top of airtight synthesising container through vent valve; When vanadium nitrogenizing reaction temperature reaches 1500 DEG C-1520 DEG C; Regulable control vent valve makes the water vapour pressure in airtight synthesising container be 2-3Mpa, and combustion synthesis reaction is from continuing to carry out; After reacting completely, the high-purity VN alloy of high nitrogen is taken out after logical nitrogen cooling in plumbago crucible, is broken into block.