Preparation method of ultramicro carbon-iron alloy material

Abstract

A preparation method of an ultramicro carbon-iron alloy material comprises the following steps: grinding a high-carbon iron alloy block, spraying the high-carbon iron alloy block into a suspension roaster in an oxygen-enriched environment, carrying out spontaneous heating partial oxidation, cooling the partially oxidized powder, detecting the contents of carbon and oxygen elements, uniformly mixing the partially oxidized powder with unoxidized high-carbon iron alloy powder according to a certain ratio, and carrying out heat treatment to obtain the ultramicro carbon-iron alloy material. And after the reaction is finished, the materials in the furnace are cooled, and the materials are discharged out of the furnace to obtain the ultra-micro carbon-iron-based metal material. According to the method, the characteristic that elemental carbon and iron in the high-carbon iron alloy material can be combusted under certain conditions is utilized, the decarburization and oxygenation conditions are accurately controlled, materials in a suspension state are not sintered, decarburization is uniform, secondary grinding is not needed, a heat source does not need to be additionally introduced, the production cost is effectively reduced, the product quality is improved, and the ultramicro carbon iron alloy material can be produced after vacuum sintering.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a method for preparing an ultrafine carbon-iron alloy material. Background Art

[0002] High-carbon ferrochrome and high-carbon ferromanganese are important ferroalloys and are widely used in the production of stainless steel and special steel. Ultrafine carbon ferroalloy materials, due to their unique low-carbon characteristics, have broad application value and an important strategic position in the fields of optimizing alloys, reducing costs, improving material properties, and powder metallurgy. The production of ultrafine carbon ferroalloy materials is mainly based on the vacuum solid-state decarburization method. In order to reduce the carbon content in high-carbon ferroalloy materials, in addition to the vacuum and high-temperature environment, it is also necessary to introduce an appropriate amount of oxygen. For this purpose, the traditional process grinds the high-carbon ferroalloy powder and then roasts it in a rotary kiln for pre-oxidation. Because the material becomes a sintered block after roasting, it needs to be ground into powder again and then mixed with unoxidized sintered high-carbon ferroalloy powder according to the carbon and oxygen content to ensure that carbon and oxygen combine and escape. This process has many disadvantages, such as the large amount of energy consumption required for rotary kiln roasting, the high hardness of the sintered block material, the difficulty of secondary grinding, and the complexity of production equipment. To avoid the trouble of sintering, there are also production processes that use direct addition of oxides. For example, patent CN1818105 grinds high-carbon ferrochrome into powder and then adds iron oxide or chromium oxide. Patent CN101260474 grinds high-carbon ferromanganese into powder and then adds iron oxide or manganese oxide before decarburization in a vacuum sintering furnace. Both of the above patents require the addition of additional oxidants. Adding iron oxide will reduce the content of the main elements in the ferroalloy and affect its value, while the cost of adding chromium oxide or manganese oxide is relatively high. Summary of the Invention

[0003] The present invention provides a method for preparing an ultrafine carbon ferroalloy material to address the deficiencies of the above-mentioned prior art and the problem that traditional high-carbon ferrochrome and high-carbon ferromanganese powders are inconvenient to prepare.

[0004] In order to achieve the purpose of the present invention, the following technologies are proposed: A method for preparing an ultrafine carbon-iron alloy material comprises the following steps: Step 01, crushing and grinding the high carbon ferroalloy block; Step 02: preheat the suspension calcining furnace, introduce oxygen-enriched air, and turn off the heat source; Step 03, spraying the high carbon ferroalloy powder into the preheated suspension calcining furnace in step 02 for partial suspension autocombustion, cooling and settling after combustion, and detecting the carbon and oxygen contents of the fired powder; Step 04, adding the high carbon ferroalloy powder of step 01 in a proportion according to the carbon and oxygen contents in step 03, mixing them evenly, and pressing them into shape; Step 05, placing the formed block material of step 04 in a vacuum sintering furnace, evacuating the vacuum and raising the temperature so that the carbon and oxygen elements in the material are combined into gas and discharged, maintaining the high temperature and vacuum state in the furnace for a certain period of time, cooling down and taking the material out of the furnace to obtain an ultrafine carbon iron alloy material.

[0005] Furthermore, in step 01, the particle size of the high carbon ferroalloy after grinding is 10-50 μm.

[0006] Furthermore, in step 02, the preheating temperature of the suspension calcining furnace is 500-1000°C.

[0007] Furthermore, in step 02, the oxygen content of the oxygen-enriched air in the suspension calcining furnace is 30-90%, the temperature in the calcining furnace is controlled to be 500-1000° C., and the residence time of the powder is 3-30 seconds.

[0008] Furthermore, in step 03, the molar ratio of carbon to oxygen in the calcined powder is controlled to be 1:1.1 to 2.0.

[0009] Furthermore, in step 04, the molar ratio of carbon to oxygen in the mixture is 1:1.01 to 1.05.

[0010] Furthermore, in step 05, the vacuum degree in the vacuum furnace is controlled to be 5-100 Pa, the temperature is controlled to be 1100-1600° C., and the insulation time is controlled to be 1-12 hours.

[0011] Furthermore, in step 05, the carbon content of the ultrafine carbon ferroalloy material is ≤0.02%, and the oxygen content is ≤0.3%.

[0012] The advantages of the above technical solution are: The present invention utilizes the principle that elemental metal elements or carbon elements are easily combustible in a powder state, and achieves pre-oxidation of carbon elements by adjusting the powder particle size, the oxygen concentration in the combustion atmosphere, and the suspension residence time. Compared with the existing process, no external heat source is required, which saves the cost of calcination heat source. There is no need to add oxides, which is conducive to stabilizing the element ratio in the alloy and reducing the production cost of using high-valent oxides.

[0013] The present invention utilizes suspension calcination technology to effectively avoid sintering of metal powder during the combustion process. The metal powder remains in a dispersed state after oxidation, and does not require secondary grinding as in the traditional rotary kiln sintering process, thereby reducing process operation procedures and operating costs. DETAILED DESCRIPTION

[0014] Example 1 High-carbon ferrochrome (C=7.11%) was crushed and ground to a particle size of 30-50um, accounting for 90%. A suspension roasting furnace with a size of φ400*5000mm was preheated to a furnace temperature of 750℃, and oxygen was introduced to maintain the oxygen concentration in the furnace at 40-45%. 100kg of high-carbon ferrochrome powder was blown into the suspension roasting furnace at a uniform speed from the bottom using oxygen-enriched air with an oxygen concentration of 40-45%. As the oxygen-enriched air flow moved from bottom to top, the high-carbon ferrochrome powder self-ignited and released heat. At the same time, the heat source of the suspension roasting furnace was turned off. The oxygen-enriched environment and the self-ignition heat release of the high-carbon ferrochrome powder maintained the furnace temperature at 800-850℃. The oxidized high-carbon ferrochrome powder left the suspension roasting furnace and was cooled. After cooling, 97.5kg of oxidized powder was collected. The carbon content was 1.21% and the oxygen content was 2.42%. The oxidized powder was mixed with 8.13 kg of high-carbon ferrochrome powder and pressed into φ30*20 mm blocks. After maintaining the mixture in a vacuum environment of 10 Pa and a temperature of 1520°C for 10 hours, the mixture was cooled to 100°C and the furnace was dismantled to obtain an ultrafine carbon ferrochrome alloy material with a carbon content of 0.0103% and an oxygen content of 0.1536%.

[0015] Example 2 High-carbon ferrochrome (C=7.11%) was crushed and ground to a particle size of 10-30 μm, accounting for 90%. A suspension roasting furnace measuring φ400*5000 mm was preheated to a furnace temperature of 880°C, and oxygen was introduced to maintain the oxygen concentration in the furnace at 35-38%. 100 kg of high-carbon ferrochrome powder was uniformly blown into the suspension roasting furnace from the bottom using oxygen-enriched air with an oxygen concentration of 35-38%. As the oxygen-enriched air flowed upward from bottom to top, the high-carbon ferrochrome powder self-ignited and released heat. At the same time, the heat source of the suspension roasting furnace was turned off, and the oxygen-enriched environment and the self-ignition heat release of the high-carbon ferrochrome powder maintained the furnace temperature at 880-900°C. The oxidized high-carbon ferrochrome powder left the suspension roasting furnace, cooled, and 99.2 kg of oxidized powder was collected. The carbon content was 1.35% and the oxygen content was 3.07%. The oxidized powder was mixed with 13.03 kg of high-carbon ferrochrome powder and pressed into φ30*20 mm blocks. After maintaining the mixture in a vacuum environment of 50 Pa and a temperature of 1550°C for 10 hours, the mixture was cooled to 100°C and the furnace was dismantled to obtain ultrafine carbon ferrochrome alloy material. The carbon content was detected to be 0.0171% and the oxygen content was 0.1227%.

[0016] Example 3 High-carbon ferromanganese (C=7.54%) was crushed and ground to a particle size of 10-20um, accounting for 95%. A suspension roasting furnace with a size of φ400*5000mm was preheated to a furnace temperature of 770℃, and oxygen was introduced to maintain the oxygen concentration in the furnace at 60-65%. 100kg of high-carbon ferromanganese powder was blown into the suspension roasting furnace at a uniform speed from the bottom using oxygen-enriched air with an oxygen concentration of 60-65%. As the oxygen-enriched air flow moved from bottom to top, the high-carbon ferromanganese powder self-ignited and released heat. At the same time, the heat source of the suspension roasting furnace was turned off. The oxygen-enriched environment and the self-ignition heat release of the high-carbon ferromanganese powder maintained the furnace temperature at 820-850℃. The oxidized high-carbon ferromanganese powder left the suspension roasting furnace and, after cooling, 96.5kg of oxidized powder was collected. The carbon content was 1.89% and the oxygen content was 3.78%. The oxidized powder was mixed with 11.74 kg of high carbon ferromanganese powder and pressed into φ30*20 mm blocks. After maintaining the mixture in a vacuum environment of 15 Pa and a temperature of 1500°C for 15 hours, the mixture was cooled to 130°C and the furnace was dismantled to obtain an ultrafine carbon ferromanganese alloy material with a carbon content of 0.0093% and an oxygen content of 0.2587%.

[0017] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It is apparent that various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the present invention. Thus, the present invention is intended to encompass such modifications and variations as long as they fall within the scope of the claims and their equivalents.

Claims

1. A method for producing an ultrafine carbon-iron alloy material, characterized in that: Including steps: Step 01, crushing and grinding the high carbon ferroalloy block; Step 02: preheat the suspension calcining furnace, introduce oxygen-enriched air, and turn off the heat source; Step 03, spraying the high carbon ferroalloy powder into the preheated suspension calcining furnace in step 02 for partial suspension autocombustion, cooling and settling after combustion, and detecting the carbon and oxygen contents of the fired powder; Step 04, adding the high carbon ferroalloy powder of step 01 in a proportion according to the carbon and oxygen contents in step 03, mixing them evenly, and pressing them into shape; Step 05, placing the formed block material of step 04 in a vacuum sintering furnace, evacuating the vacuum and raising the temperature so that the carbon and oxygen elements in the material are combined into gas and discharged, maintaining the high temperature and vacuum state in the furnace for a certain period of time, cooling down and taking the material out of the furnace to obtain an ultrafine carbon iron alloy material.

2. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 01, the high carbon ferroalloy is ground into a particle size of 10-50 μm.

3. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 02, the suspension calcining furnace is preheated to a temperature of 500-1000°C.

4. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 02, the oxygen content of the oxygen-enriched air in the suspension calcining furnace is 30-90%, the temperature in the calcining furnace is controlled to be 500-1000°C, and the powder residence time is 3-30 seconds.

5. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 03, the molar ratio of carbon to oxygen in the calcined powder is controlled to be 1:1.1-2.

0.

6. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 04, the molar ratio of carbon to oxygen in the mixture is 1:1.01-1.

05.

7. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 05, the vacuum degree in the vacuum furnace is controlled to be 5-100 Pa, the temperature is controlled to be 1100-1600° C., and the holding time is controlled to be 1-12 hours.

8. The method for producing ultrafine carbon iron alloy material according to claim 1, characterized in that: In step 05, the carbon content of the ultrafine carbon ferroalloy material is ≤0.02%, and the oxygen content is ≤0.3%.