A method of producing a chromium-aluminum alloy

Abstract

The application discloses a production method of a chromium-aluminum alloy, which comprises the following steps: raw material mixing, pretreatment, aluminum powder laying on the bottom of a furnace, ignition, first-stage refining, aluminum powder injection, second-stage refining, and cooling and discharging. The process adopts a two-step smelting method, that is, an aluminum thermal reduction reaction is adopted in the first step, and an electric heating method of a refining furnace is adopted in the second step, and the refining is two-stage. The process makes the chromium-aluminum alloy liquid with different specific gravities uniform, avoids the sinking of heavy chromium and the floating of light aluminum, and causes alloy segregation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chromium-aluminum alloy preparation, and particularly relates to a production method of chromium-aluminum alloy. BACKGROUND

[0002] The chromium-aluminum alloy product is mainly used as an alloying agent, an additive and a deoxidizing agent of an aluminum alloy profile product, and is widely used in the aerospace industry, the military industry and the building material industry.

[0003] At present, the production method of the chromium-aluminum alloy in China mainly melts pure metal chromium and metal aluminum by using an electric furnace to make the chromium-aluminum alloy. The process uses electric heating to react, and the electric heating has a slow heating speed and serious heat dissipation, so that the aluminum powder is seriously burned, and the oxygen element enters the alloy due to the contact with air in the single-element reaction process, so that the oxygen content in the alloy is high. SUMMARY

[0004] In view of the above description, the present application provides a production method of chromium-aluminum alloy, which comprises the following steps:

[0005] S1: the following raw materials are proportioned according to the mass percentage: chromium oxide: aluminum powder: lime: potassium chlorate / sodium chlorate = 1: 0.5-1: 0.1-0.2: 0.02-0.05, and then the mixture is obtained by mixing;

[0006] S2: the mixture is pretreated: the chromium oxide is dried, the lime is high-temperature calcined and decarburized, and the heating agent is dried;

[0007] S3: the aluminum powder is first laid on the bottom of the reaction furnace body, and then the pretreated mixture is loaded into the furnace body;

[0008] S4: the mixture is spread with the ignition agent, and the aluminothermic reaction is performed;

[0009] S5: the furnace body after the aluminothermic reaction is placed under the refining furnace for electric heating, the electrode heating voltage is 110-130V, and the time length is 8-10 minutes;

[0010] S6: the power is turned off, and the aluminum powder is sprayed;

[0011] S7: the electric heating is immediately performed after the spraying is completed, and the heating voltage is adjusted to 130-160V, and the time length is 8-10 minutes;

[0012] S8: the power is turned off after the refining is completed, and the cooling is performed for more than 60 hours until the furnace is discharged.

[0013] The process of the present application adopts two-step smelting, first adopts aluminum thermal reduction reaction, the reaction principle of which is ignition type, the ignition speed is fast, the combustion speed is fast, so the reaction speed is fast, and the reaction is reduction reaction, even if in contact with air, there is no problem of oxidation affecting the reaction quality, the second step adopts the way of electric heating of the refining furnace, and the refining adopts two-stage type, before blowing, smelting with lower voltage and longer time, the first stage is higher electrode, the electrode 40 is in contact with the surface layer of the slag layer, for example, the thickness of the slag layer 30 is 0-1 / 4H, the slag layer is heated, the purpose is to heat the slag layer by low-voltage large-current, improve the temperature of the slag, and make the slag melt as much as possible, and the effective metal in the slag melts and settles into the alloy liquid 20; after blowing, smelting with higher voltage and shorter time, this is the second stage, the electrode 40 is inserted into the deep position of the slag layer, for example, the thickness of the slag layer is 3 / 4-1H, the temperature can reach 2800-3000 DEG C, the chromium and aluminum alloy liquid with different specific gravities are homogenized by high temperature, so as to avoid the sinking of heavy chromium and the floating of light aluminum, and cause alloy segregation.

[0014] In the prior art, elemental chromium and elemental aluminum are used for reaction, the reaction process is in contact with air, resulting in high oxygen content and carbon content in the product. There is also a way of smelting by using an electric furnace alone for heating, and the reducing agent aluminum powder and chromium oxide are reacted, but the electric furnace heating speed is slow, the reaction efficiency is very low, and the required time is too long. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 、 2 The figure is a schematic diagram of the principle of the refining step of the present application. Figure 1 It is a one-stage refining state, Figure 2 It is a two-stage refining state.

[0016] In the figure, the reaction furnace 10, the alloy liquid 20, the slag layer 30, and the electrode 40. EMBODIMENT

[0017] Reference Figure 1 、 2 The present application provides a production method of chromium-aluminum alloy, which comprises the following steps:

[0018] S1: the following raw materials are proportioned according to mass percentage: chromium oxide: aluminum powder: lime: potassium chlorate / sodium chlorate = 1: 0.5~1: 0.1~0.2: 0.02-0.05, and then mixed to obtain a mixture;

[0019] S2: pretreatment of the mixture: drying of chromium oxide, high-temperature calcination of lime for decarburization, and drying of the heat generating agent;

[0020] S3: first, aluminum powder is laid on the bottom of the reaction furnace 10, and then the above-mentioned pretreated mixture is loaded into the furnace body;

[0021] S4: Sprinkle ignition agent on the mixture, and perform aluminothermic reaction;

[0022] S5: Place the furnace body after the aluminothermic reaction under the refining furnace to perform electric heating, the electrode heating voltage is 110-130V, and the time length is 8-10 minutes;

[0023] S6: Turn off the power and perform aluminum powder injection;

[0024] S7: Immediately perform electric heating after the injection is completed, and adjust the heating voltage to 130-160V, and the time length is 8-10 minutes;

[0025] S8: Turn off the power and cool for more than 60 hours after the refining is completed.

[0026] In the scheme, the total amount of aluminum powder is divided into three parts, the first part is added as a reducing agent in the raw material, the second part is the bottom aluminum powder, and the third part is the injected aluminum powder.

[0027] Further, in the S2 step, the chromium oxide is granulated to a particle size of about 3mm and then dried; the lime is ball milled and particle size screened, the intensity range is controlled to be 0-3mm, and is calcined at a high temperature of 1000℃ to remove carbon, the heat generating agent potassium chlorate / sodium chlorate is dried to remove water to improve the temperature.

[0028] Further, the temperature for high-temperature calcination and decarburization of the lime is 1000-1200℃.

[0029] Further, in the S3 step, the amount of aluminum powder laid at the bottom of the reaction furnace is 10-20% of the total amount of aluminum powder.

[0030] Further, in the S4 step, the ignition agent is magnesium powder.

[0031] Further, in the S6 step, the amount of aluminum powder used in the aluminum powder injection process is 10-20% of the total amount of aluminum powder. Embodiment

[0032] S1: The chromium oxide is granulated to a particle size of about 3mm and then dried, the drying temperature is 300℃; the lime is ball milled and particle size screened, the intensity range is controlled to be 0-3mm, and is calcined at a high temperature to remove carbon, the calcination temperature is 1000℃; the sodium chlorate is dried to remove water, the drying temperature is 100-200℃; the purpose of decarburization is to remove carbon in calcium carbonate to avoid entering the alloy liquid.

[0033] S2 calculate the following raw materials according to the weight ratio: chromium oxide, aluminum powder, lime, sodium chlorate = 1200 kg, 820 kg, 10 kg, 170 kg, mixing. Potassium chlorate / sodium chlorate as a heating agent, combustion can release a large amount of heat, used to supplement the heat of the alloy liquid, because chromium belongs to the refractory metal, the melting point is as high as 3000℃, the heat of aluminum powder reduction reaction is not enough to supply the reaction, so the heat is supplemented by the heating agent.

[0034] S3 the above mixture is loaded into the reaction furnace body with 225 kg of aluminum powder on the bottom, and is compacted. In this scheme, the smelting product is chromium-aluminum alloy, and the aluminum powder serves as part of the raw material entering the alloy liquid and is converted into part of the alloy product, and the other part serves as a reducing agent to reduce chromium oxide and provide heat. For the first part of the aluminum powder, entering the alloy liquid only melts the cold-state aluminum powder into a liquid state into the alloy liquid, which requires absorbing the temperature of the alloy liquid. Chromium oxide is difficult to melt, and a large amount of heat is required. In order to ensure sufficient heat required for the reduction reaction in advance, part of the aluminum powder in the raw material ratio participates in the reaction as a reducing agent, about 55%, and the other part of the aluminum powder enters the alloy liquid, is mixed uniformly with chromium oxide in advance, and the two undergo a reduction reaction after ignition. The first part of the aluminum powder is laid on the bottom in advance and does not participate in the reduction reaction in advance, so it does not absorb the heat of the reaction, which can ensure the prior performance of the reduction reaction. After the reduction reaction is completed, the preheating temperature of the alloy liquid is as high as 2000℃, which is sufficient to melt the part of the aluminum powder into aluminum liquid into the alloy liquid to form the aluminum element in the chromium-aluminum alloy.

[0035] Although the scheme cannot mix the aluminum liquid with the alloy liquid after melting the aluminum powder, in the next step of the refining step, the alloy liquid is stirred and boiled by adjusting the voltage and current, and the specific gravity of the aluminum liquid is much lower than that of chromium, so there is a natural upward state. Therefore, the aluminum powder layer laid on the bottom not only does not participate in the reduction reaction, does not absorb the heat of the reaction, does not lower the temperature of the alloy liquid, but also enters the alloy liquid in the form of an element, greatly saving the heat of the reduction reaction and reducing the energy consumption of the reduction reaction.

[0036] S4 sprinkle the ignition agent on the above compacted reaction material and ignite to perform the aluminothermic reaction.

[0037] S5 place the above aluminothermic reaction furnace body under the refining furnace and perform electric heating for 10 minutes;

[0038] S6 turn off the power and spray 200 kg of aluminum powder;

[0039] S7 immediately perform electric heating for 8 minutes after the spraying is completed;

[0040] S8 turn off the power after the refining is completed, cool for 60 hours or more to room temperature, and discharge the furnace.

[0041] The reaction of the aluminum thermal reduction reaction is:

[0042] Cr2O3 + 2Al = 2Cr + Al2O3

[0043] NaClO3 + 2Al = NaCl + Al2O3

[0044] The sample of the chromium-aluminum alloy prepared in the embodiment is detected for component content as follows: chromium Cr 50.53%, C 0.015%, S 0.009%, O 0.053%, N <0.001%, and the balance is aluminum, and the alloy weight is 1527 kg. Embodiment

[0045] S2, the following raw materials are calculated and proportioned according to weight ratio: chromium oxide, aluminum powder, lime, and sodium chlorate = 1200 kg, 800 kg, 12 kg, and 160 kg, and the materials are mixed.

[0046] S3, the mixed materials are loaded into the reaction furnace body with 100 kg of aluminum powder on the bottom, and are compacted.

[0047] S6, the power is turned off, and 200 kg of aluminum powder is sprayed;

[0048] The other process steps are the same as in Embodiment One

[0049] The sample of the chromium-aluminum alloy prepared in the embodiment is detected for component content as follows: chromium Cr 54.76%, C 0.015%, S 0.001%, O 0.062%, N <0.001%, and the balance is aluminum, and the alloy weight is 1405 kg, and the yield of metallic chromium is 93.7%.

[0050] In the above two embodiments, the yield of chromium oxide reaches 93.97%, which is 5-6 percentage points higher than the yield of metallic chromium produced by the ordinary aluminum thermal method. The yield of metallic aluminum reaches 98%-99%, and the burning loss of metallic aluminum is low.

[0051] In the above embodiments, the composition of the raw material chromium oxide is as follows: Cr2O3: 98.93%, C: 0.073%, and S: 0.02%. The composition of the aluminum powder is as follows: Al: 99.32%, Fe: 0.06%, Cu: 0.0041%, and Si: 0.038%. The CaO in the lime is greater than 88%, and the sodium chlorate NaClO3 is greater than 98%.

Claims

1. A method of producing a chromium-aluminum alloy, characterized by It comprises the following steps: S1: the following raw materials are proportioned according to mass percentage: chromium oxide: aluminum powder: lime: potassium chlorate / sodium chlorate = 1:0.5~1:0.1~0.2:0.02-0.05, and then mixed to obtain a mixture; S2: the mixture is pretreated: the chromium oxide is dried, the lime is high-temperature calcined to remove carbon, and the heat agent is dried; during the aluminum powder injection process, the amount of aluminum powder is 10-20% of the total amount of aluminum powder; S3: aluminum powder is first laid on the bottom of the reaction furnace body, and then the pretreated mixture is loaded into the furnace body; the amount of aluminum powder laid on the bottom of the reaction furnace body is 10-20% of the total amount of aluminum powder; S4: the mixture is spread with ignition agent, and aluminum thermal reaction is carried out; S5: the above aluminum thermal reaction furnace is placed under the refining furnace for electric heating, the electrode heating voltage is 110-130V, and the time length is 8-10 minutes; The electrode is higher during the electric heating process, the electrode is inserted into the slag layer with a thickness of 0-1 / 4H, and H is the thickness of the slag layer; S6: power off, and aluminum powder injection is carried out; during the aluminum powder injection process, the amount of aluminum powder is 10-20% of the total amount of aluminum powder; S7: immediately after the injection is completed, electric heating is carried out, and the heating voltage is adjusted to 130-160V, and the time length is 8-10 minutes; during the electric heating process, the electrode is inserted into the slag layer with a thickness of 3 / 4-1H, and H is the thickness of the slag layer; S8: after the refining is completed, the power is turned off and the furnace is cooled for more than 60 hours, and then the furnace is discharged.

2. The method of producing a chromium-aluminum alloy according to claim 1, characterized by: In the S2 step, the chromium oxide is granulated to a particle size of about 3mm and then dried; the lime is ball milled and particle size is screened, the intensity range is controlled to be 0-3mm, and the heat agent potassium chlorate / sodium chlorate is dried to remove water to improve the temperature.

3. The method of producing a chromium-aluminum alloy according to claim 2, characterized by: The temperature for high-temperature calcination of lime to remove carbon is 1000-1200℃.

4. The method of producing a chromium-aluminum alloy according to claim 1, characterized by: In the S4 step, the ignition agent is magnesium powder.

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