Low-melting-point aluminate slag system and vanadium-aluminum alloy smelting method

Abstract

The invention discloses a low-melting-point aluminate slag system and a vanadium-aluminum alloy smelting method. The aluminate slag system provided by the invention is located in a low-melting-point phase slagging area, the smelting requirements of the vanadium-aluminum alloy can be well met, and a non-oxidation and non-slag inclusion high-quality vanadium-aluminum alloy product is prepared; and meanwhile, in the slagging process, CaO and MgO are used for replacing CaF2 to serve as fluxing agents, the environment-friendly requirement is met, and the by-product slag has good development and utilization value.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium-aluminum alloy production, and in particular to a low-melting-point aluminate slag system and a vanadium-aluminum alloy smelting method using the slag making method. Background Art

[0002] Vanadium aluminum alloy is an important additive for producing titanium alloys Ti-6Al-4V and Ti-8Al-1Mo-1V for aerospace. Adding a certain proportion of vanadium and aluminum to titanium alloy can significantly improve the strength, toughness, formability, corrosion resistance and high temperature resistance of the alloy, which is conducive to the molding of complex aerospace components. At present, the production process of vanadium aluminum alloy is mainly prepared by spontaneous aluminothermic reduction reaction using V2O5 and Al as the main raw materials and CaF2 as a slag-making agent. However, the aluminothermic reduction process of V2O5 is fierce and the high melting point and viscosity of high-aluminum slag lead to many problems such as high raw material cost, low vanadium yield and poor product quality in this process. CN201410462462.5 proposes to use a mixture of high-purity V2O5, high-purity Al2O3 and high-purity aluminum powder as raw materials, and to carry out aluminothermic reduction reaction under vacuum conditions, and to separate the metal layer from the alumina slag after natural cooling, so as to obtain high-purity vanadium aluminum alloy. However, the patent does not add slag-forming agents. Considering that the melting point of Al2O3 is 2054°C, the method must require a higher smelting temperature to achieve a good separation effect between alumina slag and alloy. In order to suppress the violent splashing caused by the aluminothermic reduction of V2O5 and reduce the cost of raw materials, the inventor proposed in patent CN202011487100.3 to use V2O3 to replace part of V2O5 as a vanadium source to prepare vanadium-aluminum alloy, thereby reducing the cost of raw materials. CN201210357559.0, CN201810001093.8, and CN201611055819.3 successively proposed electrode-assisted heating technology for smelting vanadium-aluminum alloys based on improving the conditions for separating slag from gold and improving the properties of raw materials. The main purpose is to reheat the vanadium-aluminum alloy and slag by electrodes in the later stage of the reduction reaction, prolong the liquefaction time of vanadium-aluminum alloy and slag, ensure the full reduction of vanadium oxide by aluminum and the effective separation of slag from gold, and improve the product purity and vanadium recovery rate. However, the existing patents lack the regulation of slag composition and properties.

[0003] Similar to other pyrometallurgical processes, slag plays an important role in absorbing impurities, adjusting alloy composition and preventing metal oxidation in vanadium-aluminum alloy smelting. In addition, good slag fluidity is an important prerequisite for slag-gold separation. At present, CaF2 is usually used as a slag-making agent in the vanadium-aluminum alloy smelting process to improve the fluidity of the slag, but the effect is not significant. The slag melting point is still very high, which leads to a series of problems such as difficulty in melting the slag, high viscosity, small alloy droplets are difficult to separate from the slag, uneven alloy composition, low vanadium yield, and waste of vanadium resources. At the same time, CaF2 is not environmentally friendly and poses risks to human health and the environment, so it is gradually restricted in industrial applications. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems existing in the prior art and to provide a low melting point aluminate slag system and a vanadium aluminum alloy smelting method.

[0005] The technical solution adopted by the present invention is as follows: a low melting point aluminate slag system, wherein the components of the aluminate slag system are as follows by mass percentage: CaO: 30.00-45.00%, Al2O3: 42-58%, MgO: 0-10.00%, VO x : 0~6%, other ingredients are less than 3.00%.

[0006] Preferably, the mass ratio of CaO / MgO in the aluminate slag system is between 4.0-9.0; the mass ratio of CaO / Al2O3 is between 0.4-0.9.

[0007] Preferably, the melting point of the aluminate slag system is less than 1450°C; the viscosity of the aluminate slag system is less than 6 dPas when the temperature is higher than 1500°C; the density of the aluminate slag system is 2.5-3.0 g / cm 3 ; The surface tension of the aluminate slag is 520-560 mN / m when the temperature is higher than 1500°C.

[0008] Preferably, the aluminate slag is VO x It comes from the unreduced part of vanadium oxide, and the content of V2O5 in the unreduced part of vanadium oxide is 50-70%.

[0009] More preferably, the Al2O3 is a byproduct Al2O3 generated by aluminothermic reduction of vanadium oxide.

[0010] Further preferably, the viscosity of the aluminate slag system is measured by a rotating cylinder method; the melting temperature is obtained by drawing a viscosity-temperature curve; the density is measured by a buoyancy method; and the surface tension is measured by a maximum bubble method.

[0011] The present invention also provides a vanadium-aluminum alloy smelting method, which uses vanadium oxide as a raw material, aluminum as a reducing agent, CaO and MgO as fluxes, and the slag composition is designed as the above-mentioned low-melting-point aluminate slag system, and smelting is carried out in an electric furnace to obtain vanadium-aluminum alloy and low-melting-point aluminate slag system.

[0012] Preferably, the vanadium oxide is one of V2O3 and V2O5, or a mixture of the two.

[0013] Preferably, the fluxes CaO and MgO are derived from dolomite and limestone.

[0014] The beneficial effects of the present invention are:

[0015] 1) The present invention can meet the requirements of slag fluidity and slag-metal separation in the smelting of vanadium-aluminum alloy, and is of great significance for improving the metal yield and product quality of vanadium-aluminum alloy.

[0016] 2) The aluminate slag system proposed in the present invention is located in the slag-forming region of the low-melting-point phase, and its physical and chemical properties meet the smelting requirements and are superior to the traditional slag system.

[0017] 3) Using CaO and MgO instead of CaF2 as flux and slag-forming agent can meet environmental protection requirements, and the by-product slag has good development and utilization value. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the thermodynamic phase diagram of the low melting point aluminate slag system in the present invention. DETAILED DESCRIPTION

[0019] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0020] Example 1

[0021] 1. A group of slag samples were prepared by using analytically pure reagents CaO, MgO, Al2O3, V2O3 and V2O5. The components of the slag samples were calculated by mass percentage as follows: CaO: 37.06%, Al2O3: 52.94%, MgO: 5.00%, V2O3: 5%, CaO / Al2O3 mass fraction percentage was 0.7, and CaO / MgO mass fraction percentage was 7.4.

[0022] 2. Slag property detection

[0023] 2.1 The viscosity of the slag is measured by the rotating cylinder method: the slag sample is heated to 1400-1650°C, kept warm for more than 120 minutes, and then the slag viscosity data is measured by the rotating cylinder method using a Brookfield viscometer.

[0024] 2.2 Obtain the melting temperature by drawing the viscosity-temperature curve: After the viscosity measurement is completed, the sample is heated up to 1400-1500℃ and kept warm for 120 minutes, then the sample is cooled at a rate of 2℃ / min, and the slag viscosity data is continuously measured by the rotating cylinder method until the viscometer stops rotating due to excessive viscosity, and finally a curve of viscosity versus temperature is drawn. A 45° cut is made on the viscosity-temperature curve, and the temperature at the cut point is the melting temperature of the slag.

[0025] 2.3 Density is measured by buoyancy method: the sample is heated to 1400-1650℃ and kept warm for more than 120 minutes to ensure the balance of slag composition and temperature field in the furnace; the probe made of metal molybdenum suspended on the mass sensor is completely immersed in the slag. The buoyancy generated by the slag acts on the probe to produce a mass difference in the mass sensor, and then the density is calculated.

[0026] 2.4 The surface tension is measured by the maximum bubble method: the sample is heated to 1400-1650°C and kept warm for more than 120 minutes to ensure the balance of the slag composition and the temperature field in the furnace; at the beginning of the test, the capillary is suspended above the slag surface, the air flow rate is controlled by a mass flow meter, and the pressure difference value in the capillary is recorded in real time by a pressure difference sensor; after the pressure difference sensor records stably, the capillary is allowed to slowly descend, and when the pressure suddenly increases, it means that it has contacted the slag liquid surface; and the maximum pressure at different depths is measured, and then the surface tension is calculated.

[0027] 3. Test results: The viscosity of the slag in the temperature range of 1500-1650℃ is 1.5-3.7dPas; the melting temperature of the slag is 1380℃; the density of the slag is 2.76g / cm 3 Nearby; the surface tension of the slag is about 580mN / m. The above data are consistent with the properties of low-melting-point aluminate slag.

[0028] Example 2

[0029] 1. A group of slag samples were prepared by using analytically pure reagents CaO, MgO, Al2O3, V2O3 and V2O5. The components of the slag samples were calculated by mass percentage as follows: CaO: 42.63%, Al2O3: 47.37%, MgO: 5.00%, V2O3: 2%, V2O5: 3%, CaO / Al2O3 mass fraction percentage was 0.9, and CaO / MgO mass fraction percentage was 8.5.

[0030] 2. The detection methods for the viscosity, melting temperature, density and surface tension of the slag in this embodiment are the same as those in Embodiment 1.

[0031] 3. Test results: The viscosity of the slag in the temperature range of 1500-1650℃ is 1.3-2.2dPas; the melting temperature of the slag is 1398℃; the density of the slag is 2.78g / cm 3 Nearby; the surface tension of the slag is about 560mN / m, and the properties of the slag are all in an appropriate range.

[0032] Example 3

[0033] 1. A group of slag samples were prepared by using analytically pure reagents CaO, MgO, Al2O3, V2O3 and V2O5. The components of the slag samples were calculated by mass percentage as follows: CaO: 36.03%, Al2O3: 51.47%, MgO: 7.50%, V2O3: 1%, V2O5: 4%, the CaO / Al2O3 mass fraction percentage was 0.7, and the CaO / MgO mass fraction percentage was 4.8.

[0034] 2. The detection methods for the viscosity, melting temperature, density and surface tension of the slag in this embodiment are the same as those in Embodiment 1.

[0035] 3. Test results: The viscosity of the slag in the temperature range of 1500-1650℃ is 1.4-3.4dPas; the melting temperature of the slag is 1385℃; the density of the slag is 2.73g / cm 3 Nearby; the surface tension of the slag is about 565mN / m, and the properties of the slag are all in an appropriate range.

[0036] Example 4

[0037] V2O3 powder is used as raw material, Al particles are used as reducing agent, CaO and MgO are used as slag-forming agents, and the design is carried out according to the AlV55 alloy. At the same time, the composition of the aluminate slag is designed according to the slag composition in Example 1, and the mass percentage is: CaO: 37.06%, Al2O3: 52.94%, MgO: 5.00%, V2O3: 5%, the CaO / Al2O3 mass fraction percentage is 0.7, and the CaO / MgO mass fraction percentage is 7.4. After mixing each sample, place it in a resistance furnace with a graphite rod as a heating body, the smelting temperature is controlled at 1650°C, the smelting time is controlled at 2h, and the sample is cooled to room temperature after the smelting is completed, the slag-gold separation is observed, and the content of each element of the vanadium-aluminum alloy is detected. It was found that the slag gold had a good separation effect, and there was no oxidation and slag inclusion inside the vanadium-aluminum alloy. The mass percentage of the obtained vanadium-aluminum alloy product was as follows: V was 57.4%, Fe was 0.17%, Si was 0.15%, C was 0.04%, O was 0.06%, and N was 0.03%; the vanadium yield was 97.48%.

[0038] Comparative Example 1

[0039] A group of slag samples were obtained by mixing analytically pure reagents CaO, MgO, Al2O3, V2O3 and V2O5. The components of the slag samples were calculated by mass percentage as follows: CaO: 15%, Al2O3: 75%, MgO: 5%, V2O3: 5%, CaO / Al2O3 mass fraction percentage was 0.2, and CaO / MgO mass fraction percentage was 3.0. The viscosity of the slag in the temperature range of 1500-1650℃ was in the range of 13-26dPas, which was far beyond the appropriate slag viscosity range.

[0040] Comparative Example 2

[0041] V2O3 powder is used as raw material, Al particles are used as reducing agent, CaO and MgO are used as slag-forming agents, and the design is based on AlV55 alloy. At the same time, the composition of aluminate slag is designed according to the slag composition of comparative example 1, which is calculated by mass percentage as follows: CaO: 15%, Al2O3: 75%, MgO: 5%, V2O3: 5%, CaO / Al2O3 mass fraction percentage is 0.2, and CaO / MgO mass fraction percentage is 3.0. After mixing each sample, place it in a resistance furnace with a graphite rod as the heating body, the smelting temperature is controlled at 1650℃, the smelting time is controlled at 2h, and the sample is cooled to room temperature after the experiment, and the slag-gold separation is observed and the content of each element of the vanadium-aluminum alloy is detected. It was found that the slag-gold separation was poor, and the alloy particles were entrained in the slag.

[0042] In summary, the slag designed according to the low melting point aluminate slag system proposed in the present invention can meet the vanadium aluminum alloy smelting requirements very well, and produce high-quality vanadium aluminum alloy products without oxidation and slag inclusion. However, the slag not within the aluminate slag system proposed in the present invention cannot meet the vanadium aluminum alloy smelting requirements at all.

[0043] The specification and drawings of the present invention are considered to be illustrative rather than restrictive. On the basis of the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features according to the disclosed technical content without creative labor, all of which are within the protection scope of the present invention.

Claims

1. A low melting point aluminate slag system, characterized in that: The components of the aluminate slag system are as follows by mass percentage: CaO: 30.00-45.00%, Al2O3: 42-58%, MgO: 0-10.00%, VO x : 0~6%, other ingredients are less than 3.00%.

2. A low melting point aluminate slag system according to claim 1, characterized in that: The mass ratio of CaO / MgO in the aluminate slag system is between 4.0 and 9.0; the mass ratio of CaO / Al2O3 is between 0.4 and 0.

9.

3. A low melting point aluminate slag system according to claim 1, characterized in that: The melting temperature of the aluminate slag system is less than 1450°C; the viscosity of the aluminate slag system is less than 6dPas when the temperature is higher than 1500°C; the density of the aluminate slag system is 2.5-3.0g / cm 3 ; The surface tension of the aluminate slag is 520-560 mN / m when the temperature is higher than 1500°C.

4. A low melting point aluminate slag system according to claim 1, characterized in that: The aluminate slag system has VO x It comes from the unreduced part of vanadium oxide, and the content of V2O5 in the unreduced part of vanadium oxide is 50-70%.

5. The low melting point aluminate slag system according to claim 1, characterized in that: The Al2O3 is a byproduct Al2O3 generated by aluminothermic reduction of vanadium oxide.

6. A low melting point aluminate slag system according to claim 1, characterized in that: The viscosity of the aluminate slag system is measured by a rotating cylinder method; the melting temperature is obtained by drawing a viscosity-temperature curve; the density is measured by a buoyancy method; and the surface tension is measured by a maximum bubble method.

7. A vanadium-aluminum alloy smelting method, characterized in that: Vanadium oxide is used as raw material, aluminum is used as reducing agent, CaO and MgO are used as flux, and the slag composition is designed according to the low melting point aluminate slag system as described in any one of claims 1 to 6. Smelting is carried out in an electric furnace to obtain vanadium aluminum alloy and low melting point aluminate slag system.

8. A vanadium-aluminum alloy smelting method according to claim 7, characterized in that: The vanadium oxide is one of V2O3 and V2O5 or a mixture of the two.

9. A vanadium-aluminum alloy smelting method according to claim 7, characterized in that: The fluxes CaO and MgO are derived from dolomite and limestone.

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