CN115181831A

CN115181831A - Graphite carburant and preparation method thereof

Info

Publication number: CN115181831A
Application number: CN202210831805.5A
Authority: CN
Inventors: 董梦
Original assignee: Qingdao Weijie Graphite Co ltd
Current assignee: Qingdao Weijie Graphite Co ltd
Priority date: 2022-07-15
Filing date: 2022-07-15
Publication date: 2022-10-14

Abstract

The application relates to the field of carburant, and particularly discloses a graphite carburant and a preparation method thereof. A graphite carburant comprises the following raw materials in parts by weight: 70-80 parts of crystalline flake graphite, 2-4 parts of silicon carbide, 1-2 parts of ferromanganese alloy powder, 1-2 parts of expandable graphite and 8-10 parts of binder; the binder is prepared by mixing sodium hydroxide, sodium carboxymethyl cellulose and starch in a weight ratio of 1. The carburant has longer floating time and faster melting rate in molten iron, so that the carburant has good wettability and excellent carbon absorption rate in the molten iron, and the hardness and the glossiness of a product can be improved.

Description

Graphite carburant and preparation method thereof

Technical Field

The application relates to the field of carburant, in particular to a graphite carburant and a preparation method thereof.

Background

The recarburizing agent is a carbonaceous substance added to supplement the carbon content of the burnt loss in the steel smelting process. At present, the carburant generally comprises wood carbon, coal carbon, coke, artificial graphite, calcined petroleum coke and the like. The carburant of wood carbon, coal carbon and coke has more ash content and impurities, which can affect the mechanical property of steel and easily form quality defects such as shrinkage cavity, white spot and the like. The artificial graphite carburant is prepared with powdered high quality calcined petroleum coke as main material and has excellent carburant effect, but its use is limited owing to its high cost. At present, a widely applied carburant is a petroleum coke carburant, and the petroleum coke is a byproduct obtained by refining crude oil and has lower cost; because of its high impurity content, it must be calcined before it can be used as a carburant. In the casting process, after the carburant is added, the carburant is required to be effectively combined with molten iron for wetting, so that the phenomenon that the carburant floats on the surface of the molten iron and burns due to different densities can be avoided. However, petroleum coke carburant has a relatively low specific gravity and poor penetrability after being put into a ladle, and the stirring method, force and adding time of molten iron need to be strictly controlled, so that the operation process is relatively complicated.

Therefore, the current carburant has certain defects.

Disclosure of Invention

In order to solve the technical problems, the application provides a graphite carburant and a preparation method thereof.

In a first aspect, the present application provides a graphite carburant, which adopts the following technical scheme:

a graphite carburant comprises the following raw materials in parts by weight:

70-80 parts of crystalline flake graphite, 2-4 parts of silicon carbide, 1-2 parts of ferromanganese alloy powder, 1-2 parts of expandable graphite and 8-10 parts of binder;

the binder is prepared by mixing sodium hydroxide, sodium carboxymethylcellulose and starch in a weight ratio of 1.

By adopting the technical scheme, the crystalline flake graphite is used as the main raw material of the carburant, and the silicon carbide, the ferromanganese alloy powder and the expandable graphite are matched and bonded under the action of the binder consisting of sodium hydroxide, sodium carboxymethylcellulose and starch to increase the forming granularity of the carburant, so that the obtained carburant has a good wetting effect in molten steel; when the recarburizer is put into molten steel, the recarburizer can slowly rise and can be rapidly dissolved, and the recarburizer has a large specific surface area, can achieve a good recarburization effect, and improves the hardness and smoothness of a product.

Optionally, the flake graphite is prepared by mixing medium-carbon flake graphite with the particle size of 20-30 μm and high-carbon flake graphite with the particle size of 70-80 μm according to the weight ratio of 1:1.

Flake graphite can be classified into high-carbon flake graphite, medium-carbon flake graphite and low-carbon flake graphite; the high-carbon flake graphite is low in doping amount and high in price, and the cost of the carburant can be increased; the ash content of the low-carbon flake graphite is high, so that the recarburization effect is influenced; by adopting the technical scheme, the flake graphite consists of medium-carbon flake graphite with the particle size of 20-30 microns and high-carbon flake graphite with the particle size of 70-80 microns, and the obtained carburant has good solubility and diffusivity, so that the carburant has a good carburant effect on ironworks.

Optionally, the manganese content in the ferromanganese alloy powder is 60-90%.

By adopting the technical scheme, the graphite has a small specific gravity, and is easy to float on the surface of molten steel after being put into the molten steel and can not be completely dissolved, so that the recarburization effect is influenced; after the ferromanganese alloy is added, the density of the carburant can be increased, so that the carburant can be immersed in molten steel for a long time, and the melting of graphite powder is facilitated; meanwhile, manganese has a reduction effect, so that selective oxidation can be realized, and the reaction between carbon and oxygen can be inhibited, so that the burning loss of carbon can be reduced.

Optionally, the starch is modified starch, and the modified starch is prepared by the following method:

taking 30-40 parts by weight of sodium starch octenyl succinate, adding the sodium starch octenyl succinate into 100 parts by weight of water at 90-95 ℃, and uniformly stirring to obtain sodium starch octenyl succinate emulsion;

adding 10-20 parts of polyethylene glycol 4000 into the sodium starch octenyl succinate emulsion, stirring for 1-2h, and standing at 30-40 ℃ for 12-20h; filtering and drying to obtain the modified starch.

By adopting the technical scheme, the starch is prepared from polyethylene glycol 4000 modified sodium octenyl succinate starch, the obtained modified starch still has good bonding stability in an alkaline environment, and the obtained binder has good forming stability by matching with sodium carboxymethylcellulose and sodium hydroxide, so that the loose phenomenon caused by insufficient bonding performance can be avoided, the binder is put into molten steel, the recarburizing agent can slowly rise and can be rapidly dissolved, and a good recarburizing effect is achieved.

Optionally, the graphite carburant is cylindrical, the diameter of the graphite carburant is 25-30mm, and the length of the graphite carburant is 20-25mm.

By adopting the technical scheme, the recarburizing effect of the recarburizing agent is influenced by the floating state and the dissolving and diffusing state of the recarburizing agent in the molten steel, and the performances are influenced by the shape and the structure of the recarburizing agent; by adopting the technical scheme, the carburant is of a cylindrical structure with the diameter of 40-45mm and the length of 20-25mm, so that the carburant can slowly rise in molten steel and can be rapidly dissolved, and the carburant can be improved in carburant efficiency; and it is easy to produce and easy to process.

In a second aspect, the present application provides a method for preparing a graphite carburant, which adopts the following technical scheme:

a preparation method of a graphite carburant comprises the following steps:

s1, uniformly mixing the crystalline flake graphite, the silicon carbide, the ferromanganese alloy powder, the expandable graphite and the binder according to the proportion to obtain mixed powder;

s2, adding water into the mixed powder, and uniformly mixing and stirring to obtain a mixture;

s3, pressing the mixture into a cylindrical shape to obtain granules;

and S4, drying the granules to obtain the graphite carburant.

Optionally, the addition amount of the water is 8-10% of the weight of the mixed powder.

Optionally, the drying temperature is 70-80 ℃, and the drying time is 12-16h.

Optionally, a granule surface treatment process is added between S3 and S4, and specifically includes the following steps:

spraying modified starch milk with the weight of 3-5% of the weight of the granules on the surfaces of the granules, and then stirring the granules at the speed of 200-400r/min for 1-2h under the conditions that the temperature is 60-70 ℃ and the pressure is-0.06-0.09 MPa.

By adopting the technical scheme, the modified starch milk is sprayed on the surface of the granular material, and the low-temperature negative pressure condition is utilized, so that the modified starch milk carries out surface coating treatment on the granular material, the wettability and penetrability of the carburant in molten steel can be improved, and the carburant effect can be favorably improved.

Optionally, the modified starch milk is prepared by uniformly mixing and stirring modified starch and water according to the weight ratio of 1:3.

In summary, the present application has the following beneficial effects:

1. the method takes the crystalline flake graphite as a main raw material of the recarburizing agent, and the crystalline flake graphite is bonded under the action of a binder consisting of sodium hydroxide, sodium carboxymethylcellulose and starch through the matching of silicon carbide, ferromanganese alloy powder and expandable graphite so as to increase the forming granularity of the recarburizing agent, so that the obtained recarburizing agent has a good wetting effect in molten steel; when the recarburizing agent is added into molten steel, the recarburizing agent can slowly rise and can be quickly dissolved, the recarburizing agent has a large specific surface area, a good recarburizing effect can be achieved at the temperature of 1200 ℃, and the hardness and the smoothness of a product are improved.

2. The starch is prepared from polyethylene glycol 4000 modified sodium starch octenyl succinate, so that the obtained modified starch still has good bonding stability in an alkaline environment, and the phenomenon of looseness caused by insufficient bonding performance can be avoided.

3. This application utilizes the condition of low temperature negative pressure through spraying modified starch milk at the surface of aggregate for modified starch milk carries out surface coating to the aggregate and handles, can improve infiltration and the penetrability of carburant in the molten steel, thereby is favorable to improving the carburant effect.

Detailed Description

The present application will be described in further detail with reference to examples.

Preparation example of modified starch

The starting materials in the preparation examples are commercially available, unless otherwise specified.

Preparation example 1

Taking 3kg of sodium starch octenyl succinate, adding the sodium starch octenyl succinate into 10kg of water with the temperature of 95 ℃, and uniformly stirring to obtain sodium starch octenyl succinate emulsion;

adding 1kg of polyethylene glycol 4000 into the sodium starch octenyl succinate emulsion, stirring for 1.5h, and standing for 16h at the temperature of 35 ℃; then obtaining a precipitate after decompression and filtration; and drying the precipitate at the temperature of 80 ℃ for 10h to obtain the modified starch.

Preparation example 2

Taking 4kg of sodium starch octenyl succinate, adding the sodium starch octenyl succinate into 10kg of water with the temperature of 95 ℃, and uniformly stirring to obtain sodium starch octenyl succinate emulsion;

adding 1.5kg of polyethylene glycol 4000 into the sodium starch octenyl succinate emulsion, stirring for 1.5h, and standing for 16h at the temperature of 35 ℃; then obtaining a precipitate after decompression and filtration; and drying the precipitate at the temperature of 80 ℃ for 10h to obtain the modified starch.

Examples

The starting materials in the examples are all commercially available, unless otherwise specified. Wherein, the manganese content in the ferromanganese alloy powder is 90 percent, the carbon content is 1.5 percent, and the fineness is 300 meshes.

Examples 1 to 6

As shown in Table 1, the main difference between examples 1 to 6 is in the amount and source of the raw materials, and example 1 will be described below as an example.

The preparation method of the graphite carburant provided in example 1 includes the following steps:

s1, uniformly mixing flake graphite, silicon carbide, ferromanganese alloy powder, expandable graphite and a binder according to a ratio to obtain mixed powder;

s2, adding water accounting for 10% of the weight of the mixed powder into the mixed powder, and uniformly mixing and stirring to obtain a mixture;

s3, pressing the mixture into a cylinder according to the compression ratio of 3:1 to obtain granules;

and S4, drying the granules at the temperature of 75 ℃ for 14h to obtain the graphite carburant with the diameter of 25mm and the length of 20 mm.

TABLE 1 raw material usage Scale (unit: kg) for examples 1-6

Example 7

The difference between the embodiment and the embodiment 5 is that a granule surface treatment process is added between S3 and S4, and the method specifically comprises the following steps:

(1) Uniformly mixing and stirring the modified starch prepared in the preparation example 1 and water according to the weight ratio of 1:3 to obtain modified starch milk;

(2) Spraying modified starch milk with weight of 4% of the granule surface, and stirring at 300r/min for 1.5 hr at 65 deg.C and-0.09 MPa.

Comparative example

Comparative example 1

The comparative example is different from example 1 in that silicon carbide, ferromanganese alloy powder, expandable graphite were replaced with the same amount of flake graphite.

Performance test

The performance of the carburant prepared according to the method in examples 1 to 7 and comparative example 1 was tested as a sample, and the test results are reported in table 2.

The using method comprises the following steps: spreading the recarburizer in a medium frequency induction furnace by 0.5 percent of adding amount, then adding waste iron, heating until the waste iron is melted into molten iron, and when the temperature reaches 1500 ℃, uniformly stirring by using a rolling rod and removing slag. And detecting the absorptivity of the recarburizer through stokehole spectral analysis.

Melting rate: the recarburizing effect of the recarburizing agent can be described by the absorption rate and the melting rate of the recarburizing agent, and the higher the melting rate of the recarburizing agent is, the easier the recarburizing agent is dispersed in molten iron, and the better recarburizing effect can be achieved. The detection method comprises the following steps: accurately weighing the weight of the recarburizer sample, then putting the recarburizer into the molten steel, keeping the recarburizer for a certain time, recording the time, weighing the residual weight of the recarburizer again, and calculating the melting rate in unit time = (the original weight-the residual weight after the molten iron is put into the molten iron is fixed)/time.

Floating time: because the density of the recarburizer is less than that of molten steel, the recarburizer at the bottom of the furnace can gradually float upwards due to the melting of waste iron, and if the floating speed of the recarburizer is too high, the recarburizer can float on the surface of molten iron, so that the recarburization effects of the upper layer and the lower layer of the product are inconsistent, and the product quality is influenced.

TABLE 2 Performance test Table for carburant in examples 1 to 7 and comparative example 1

It can be seen from the combination of example 1 and comparative example 1 and table 2 that the carburant of example 1 of the present application has a better carburant water absorption rate, a higher melting rate and a longer floating time, indicating that the carburant of the present application has a better carburant effect than the carburant of comparative example 1.

It can be seen from the combination of examples 1, 3 and 4 and table 2 that the recarburizing agent of example 1 has better recarburization absorptivity, higher melting rate and longer floating time, which indicates that the recarburization effect of the scale graphite is better than that of the scale graphite with single grain size when the scale graphite is compounded by using medium-carbon scale graphite with the grain size of 30 μm and high-carbon scale graphite with the grain size of 80 μm.

As can be seen by combining the working examples 1 and 5 and the table 2, the carburant of the working example 5 has better carburant absorption rate, higher melting rate and longer floating time, which shows that the starch prepared by the preparation example 1 can improve the carburant effect of the carburant.

It can be seen from the combination of examples 5, 7 and 4 and the combination of table 2 that the recarburizing agent of example 7 has better recarburization absorptivity, higher melting rate and longer floating time, which indicates that the recarburizing agent can improve the degree of wetting in the molten iron, improve the retention time in the molten iron and improve the recarburization effect after surface treatment in the preparation process.

The recarburizing agent has the advantages of high carbon content and stable recarburizing effect, is easy to disperse in molten steel, has good fluidity, has long floating time in molten iron due to large specific gravity, has good wettability in the molten iron, and has excellent carbon absorption rate, so that the hardness and the glossiness of a product can be improved.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims

1. The graphite carburant is characterized by comprising the following raw materials in parts by weight:

the binder is prepared by mixing sodium hydroxide, sodium carboxymethyl cellulose and starch in a weight ratio of 1.

2. A graphite recarburizer according to claim 1, wherein the flake graphite is prepared by mixing medium-carbon flake graphite having a particle size of 20 to 30 μm and high-carbon flake graphite having a particle size of 70 to 80 μm in a weight ratio of 1:1.

3. The graphitic recarburizing agent according to claim 1, wherein the manganese content of the ferromanganese alloy powder is 60-90%.

4. The graphite recarburizer according to claim 1, wherein the starch is a modified starch prepared by the following method:

taking 30-40 parts by weight of sodium starch octenyl succinate, adding the sodium starch octenyl succinate into 100 parts by weight of water at the temperature of 90-95 ℃, and uniformly stirring to obtain sodium starch octenyl succinate emulsion;

5. The graphite recarburizer of claim 1, wherein the graphite recarburizer is cylindrical, has a diameter of 25 to 30mm and a length of 20 to 25mm.

6. A method of preparing the graphite recarburizer of claim 1, comprising the steps of:

s3, pressing the mixture into a cylindrical shape to obtain granules;

and S4, drying the granules to obtain the graphite carburant.

7. The method of claim 6, wherein the amount of water added is 8-10% by weight of the powder mixture.

8. The method of claim 6, wherein the drying temperature is 70-80 ℃ and the drying time is 12-16 hours.

9. The method for preparing the graphite carburant according to claim 6, wherein a step of treating the surface of the pellet is added between S3 and S4, and the method specifically comprises the following steps:

10. The method for preparing the graphite carburant according to claim 9, wherein the modified starch milk is prepared by uniformly mixing and stirring the modified starch according to claim 4 and water according to a weight ratio of 1:3.