Method for preparing calcium carbide by using byproduct carbon of acetylene prepared by thermal cracking of methane

Abstract

The invention discloses a method for preparing calcium carbide by using byproduct carbon of acetylene prepared by methane thermal cracking. The method comprises the following steps: mixing the byproduct carbon of acetylene prepared by methane thermal cracking, a calcium source and a binder with a catalytic effect, carrying out compression molding, drying, and heating in an inert atmosphere to obtain the calcium carbide, the binder comprises at least one of potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignin sulfonate, potassium lignin sulfonate, magnesium lignin sulfonate and calcium lignin sulfonate. According to the method, the nanoscale byproduct carbon is bonded through the binder with the catalytic effect, metal ions in the binder can catalyze the reaction, calcium carbide is promoted to be generated, and the problem of resource utilization of the byproduct carbon is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of by - product carbon treatment, and particularly relates to a method for preparing calcium carbide by using by - product carbon from methane pyrolysis to produce acetylene. Background Art

[0002] Acetylene (C2H2) is an important basic raw material in the chemical industry. Methane pyrolysis is one of the main ways to produce acetylene industrially, but this way will produce a large amount of by - product carbon. At present, the industry mostly uses direct incineration to treat these by - product carbons. This method usually requires expensive combustion devices and will also cause problems such as secondary by - product carbon dust pollution.

[0003] The resource utilization of by - product carbon is a very promising development direction. By - product carbon has the following characteristics: complex composition, containing various carbon structures such as amorphous carbon and graphite carbon, and there are organic substances on the surface, such as polycyclic aromatic hydrocarbons, etc.; it is in powder form and has fine particles with a particle size in the nanometer range. These characteristics make it difficult to remove by - product carbon and have poor economy. Developing an efficient and clean conversion technology for by - product carbon requires full consideration of the above characteristics of by - product carbon.

[0004] Calcium carbide (the main component is calcium carbide, CaC2) is an important product in coal chemical industry and also a key raw material for acetylene preparation and the synthesis of downstream derivatives. The production of calcium carbide mainly uses the electric arc method. The main process of the traditional electric arc method is: adding a mixture of lump coke (5 - 30 mm) and calcium oxide (5 - 30 mm) into an electric furnace, and reacting under the condition of high temperature (above 2000 °C) generated by the electric arc. The generated CO gas is discharged from the upper part of the furnace body, and the molten CaC2 is discharged from the bottom of the furnace and cooled and crushed to obtain the finished product.

[0005] The new electric arc method is to react pulverized coal with calcium - based materials at high temperature in an electric arc furnace. For example, the patent specification with the publication number CN106241810A discloses a method for producing calcium carbide, including the following steps: A. Pyrolyzing coal in a pyrolysis furnace to generate pyrolysis carbon at temperature T1, and the pyrolysis carbon is output from the pyrolysis carbon discharge port of the pyrolysis furnace; B. Feeding the pyrolysis carbon into a kneading and briquetting device from the raw material inlet of the kneading and briquetting device, and also feeding quicklime at temperature T2 and binder at temperature T3 into the kneading and briquetting device; uniformly mixing, kneading, and briquetting the pyrolysis carbon, quicklime, and binder into pellets in the kneading and briquetting device, and sending the pellets out from the pellet discharge port of the kneading and briquetting device; C. Feeding the pellets into an electric arc furnace from the pellet inlet of the electric arc furnace to produce calcium carbide in the electric arc furnace. The binder used in this patented technology is one or more of coal tar, asphaltene, anthracene oil, tire powder, rubber powder, plastic particles, phosphoric acid, phosphates, phenolic resin, and epoxy resin. However, pulverized coal contains a large amount of ash, and the inorganic substances in the ash will produce calcium carbide slag that is difficult to recycle, thus generating a large amount of solid waste and increasing the environmental burden.

[0006] The patent specification with the publication number CN103708458A discloses a method for preparing calcium carbide. The method includes: pyrolyzing waste tires to obtain high-temperature oil and gas, iron wire, and nano-sized tire carbon black; mixing the nano-sized tire carbon black with a calcium-based raw material to obtain a mixed material; subjecting the mixed material to a shaping process to obtain a block-shaped raw material for furnace charging; and smelting the block-shaped raw material for furnace charging in an electric arc furnace to obtain calcium carbide, where the smelting process is carried out at 1400 - 1750 °C for 5 - 45 minutes, and the gas generation capacity of the obtained calcium carbide product can reach 290 L / kg. The patented technology uses nano-sized tire carbon black, whose composition, characteristics, etc. are very different from the by-product carbon of the present invention.

[0007] Currently, there is no mature technology for efficiently preparing high-quality calcium carbide using the by-product carbon from methane pyrolysis to produce acetylene. The main reason is that the high graphitization degree of the by-product carbon leads to strong reaction inertness of the material. Summary of the Invention

[0008] In view of the above technical problems and the deficiencies in the art, the present invention provides a method for preparing calcium carbide using the by-product carbon from methane pyrolysis to produce acetylene. By adding a catalytic binder, the nano-sized by-product carbon is mixed with a calcium source and then pressed into shape. At the same time, metal ions (potassium, sodium, calcium, magnesium) in the binder can play a catalytic role to promote the conversion of the by-product carbon into calcium carbide, breaking through the reaction inertness barrier of the by-product carbon and realizing the preparation of calcium carbide from the by-product carbon. This can not only solve the problem of solid waste disposal of the by-product carbon from methane pyrolysis to produce acetylene, but also produce high-value-added calcium carbide. Moreover, the calcium carbide slag generated by hydrolyzing the obtained calcium carbide to produce acetylene has no ash content and can be recycled and reused to produce acetylene together with the by-product carbon again, forming a complete closed-loop of resource utilization.

[0009] The specific technical solution is as follows: See Figure 1 , a method for preparing calcium carbide using the by-product carbon from methane pyrolysis to produce acetylene, including: mixing the by-product carbon from methane pyrolysis to produce acetylene, a calcium source, and a catalytic binder, pressing into shape, drying, and then heating in an inert atmosphere to obtain calcium carbide; The binder includes at least one of potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignosulfonate, potassium lignosulfonate, magnesium lignosulfonate, calcium lignosulfonate. Preferably, it includes at least one of calcium humate, calcium carboxymethyl cellulose, calcium lignosulfonate. Preferably, the binder can make the gas generation capacity of the obtained calcium carbide higher and the reaction conditions such as the temperature required for preparing calcium carbide milder.

[0010] The by - product carbon produced from the thermal pyrolysis of methane to acetylene is different from other carbon sources. Its main component is carbon black, and it also contains a small amount of amorphous carbon and surface - adsorbed organic carbon species (such as polycyclic aromatic hydrocarbons and other carbonaceous compounds). Its particle size is in the nanometer range, and it contains almost no ash. Theoretically, it can avoid the impurity problem of carbide slag and improve the recycling efficiency.

[0011] Due to its complex composition and high graphitization degree, the by - product carbon produced from the thermal pyrolysis of methane to acetylene is regarded by the industry as waste that cannot be directly used in calcium carbide synthesis. Through the collaborative design of a specific binder system and process technology, this invention realizes the efficient conversion of by - product carbon into calcium carbide and constructs a closed - loop recycling system, solving the problem of the incompatibility between the physical properties of by - product carbon and the calcium carbide production process. This invention converts the by - product carbon produced from the thermal pyrolysis of methane to acetylene into calcium carbide, which can not only solve the problem of by - product carbon solid waste disposal but also produce high - value - added calcium carbide, realizing the efficient utilization of resources.

[0012] The binder used in this invention is not a single binding medium, and its particularity lies in the synergy of the organic carrier - metal ions. The metal ions (K, Na, Mg, Ca) in the binder are pre - dispersed through the organic carrier to form nano - active sites. And potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignosulfonate, potassium lignosulfonate, magnesium lignosulfonate, and calcium lignosulfonate have low melting points, and the formed liquid phase is conducive to improving the contact of raw materials. Humic acid contains carboxyl groups, phenolic hydroxyl groups, etc., carboxymethyl cellulose contains carboxymethyl groups, and lignosulfonic acid contains sulfonic acid groups. These functional groups fix the metal ions (K, Na, Mg, Ca) as highly dispersed active sites through chelation or ion exchange, which can activate the by - product carbon, thereby promoting the reaction of highly graphitized by - product carbon with calcium source to produce calcium carbide, breaking through the reaction inertness barrier caused by the high graphitization degree of methane pyrolysis by - product carbon and realizing the resource utilization of by - product carbon.

[0013] In some embodiments, in the method for preparing calcium carbide using the by - product carbon produced from the thermal pyrolysis of methane to acetylene, the calcium source may include one or several mixtures of calcium carbonate, calcium oxide, calcium hydroxide, cyanamide waste residue, and carbide slag.

[0014] In some embodiments, in the method for preparing calcium carbide using the by - product carbon produced from the thermal pyrolysis of methane to acetylene, based on the total mass of the calcium source and the by - product carbon produced from the thermal pyrolysis of methane to acetylene being 100%, the mass ratio of the binder can be 1% - 20%, such as 5%, 10%, 15%, etc.

[0015] Based on the special selection and dosage limitation of the binder, this invention makes adaptive adjustments to the dosage ratio relationship between the by - product carbon and the calcium source.

[0016] In some embodiments, in the method of preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene, the mass ratio of the calcium source to the by-product carbon from the thermal cracking of methane to produce acetylene can be 2~5:1, for example 3:1, 4:1, etc.

[0017] In the present invention, the inert atmosphere refers to an atmosphere that does not participate in the reaction, such as one or more combinations of nitrogen (N2) atmosphere, argon and other rare gas atmospheres, etc.

[0018] The method of the present invention utilizes a catalytic binder, significantly reducing the temperature required for the heating reaction between the byproduct carbon and a calcium source to produce calcium carbide. In some embodiments, the method of preparing calcium carbide using the byproduct carbon from the thermal cracking of methane to produce acetylene can be performed at a heating temperature of 1000-1800°C, for example, 1500°C.

[0019] In some embodiments, in the method for preparing calcium carbide using the by-product carbon from the thermal cracking of methane to produce acetylene, the heating time can be 30 to 90 minutes, for example, 60 minutes.

[0020] The method for preparing calcium carbide using the by-product carbon from the thermal cracking of methane to produce acetylene, wherein the gas emission of the calcium carbide is not less than 260 L / kg, further not less than 270 L / kg, and exemplarily between 270 and 295 L / kg.

[0021] The method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene is described. The calcium carbide is ash-free, and the carbide slag obtained by hydrolyzing the carbide to produce acetylene has calcium hydroxide as the main component, which also does not contain ash and can be directly recycled as a calcium source. In some embodiments, the method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene also includes a carbide slag recycling process. The carbide slag recycling process includes: using the carbide slag produced after the calcium carbide is hydrolyzed to obtain acetylene gas as part or all of the calcium source, mixing it with the by-product carbon from the thermal cracking of methane to produce acetylene and a catalytic binder, pressing and molding, drying, and then heating in an inert atmosphere to obtain calcium carbide.

[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a method for preparing calcium carbide using by-product carbon from the thermal cracking of methane to produce acetylene. After the methane cracking by-product carbon is mixed with a calcium source through a catalytic binder, the activity of the mixed raw materials is increased, breaking through the reaction inertness barrier caused by the high degree of graphitization of the methane cracking by-product carbon. The by-product carbon and calcium sources such as calcium carbonate are converted into high-value-added calcium carbide. In addition, the carbide slag produced by the hydrolysis of the obtained calcium carbide to produce acetylene is ash-free and can be recycled and used again to produce acetylene together with the by-product carbon, forming a complete closed loop of resource utilization. The method of the present invention solves the problem of solid waste disposal of the by-product carbon and realizes the resource utilization of the by-product carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the method for preparing calcium carbide using the by - product carbon produced by the thermal cracking of methane to acetylene in the present invention.

[0024] Figure 2 This is a graph showing the relationship between the gas - generating capacity of the calcium carbide obtained in Examples 1 - 4 and the binder humate. Detailed implementation manners

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. For the operating methods without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions or in accordance with the conditions recommended by the manufacturer.

[0026] In the following examples, an appropriate amount of calcium carbide product is taken, and the volume of acetylene gas is measured by dropping water to calculate the gas - generating capacity of calcium carbide. The gas - generating capacity of calcium carbide is defined as the volume of acetylene gas generated by the reaction of unit mass of calcium carbide with water, and it is a key index to measure the quality and production efficiency of calcium carbide.

[0027] Example 1:

[0028] Using cyanamide waste residue as the calcium source, the calcium source and the by - product carbon powder are mixed in a mass ratio of 4:1 through the binder calcium humate, and the amount of the binder accounts for 5wt% of the sum of the amounts of the calcium source and the by - product carbon. A mixed raw material is prepared. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain a calcium carbide product. After the product is subjected to gas - generating detection, its gas - generating capacity reaches 295 L / kg, as Figure 2 shown.

[0029] Example 2:

[0030] Using cyanamide waste residue as the calcium source, the calcium source and the by - product carbon powder are mixed in a mass ratio of 4:1 through the binder potassium humate, and the amount of the binder accounts for 5wt% of the sum of the amounts of the calcium source and the by - product carbon. A mixed raw material is prepared. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain a calcium carbide product. After the product is subjected to gas - generating detection, its gas - generating capacity reaches 285 L / kg, as Figure 2 shown.

[0031] Example 3:

[0032] Using cyanamide waste residue as the calcium source, the calcium source and by-product carbon powder are mixed at a mass ratio of 4:1 through the binder sodium humate. The dosage of the binder accounts for 5 wt% of the sum of the calcium source and by-product carbon dosage, and a mixed raw material is prepared. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain calcium carbide product. The gas generation amount of the product is detected by gas evolution, and the gas generation amount reaches 279 L / kg, as Figure 2 shown.

[0033] Example 4:

[0034] Using cyanamide waste residue as the calcium source, the calcium source and by-product carbon powder are mixed at a mass ratio of 4:1 through the binder magnesium humate. The dosage of the binder accounts for 5 wt% of the sum of the calcium source and by-product carbon dosage, and a mixed raw material is prepared. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain calcium carbide product. The gas generation amount of the product is detected by gas evolution, and the gas generation amount reaches 271 L / kg, as Figure 2 shown.

[0035] Example 5:

[0036] Using calcium carbonate as the calcium source, the calcium source and by-product carbon powder are mixed at a mass ratio of 4:1 through the binder sodium lignosulfonate. The dosage of the binder accounts for 5 wt% of the sum of the calcium source and by-product carbon dosage, and a mixed raw material is prepared. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in a reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain calcium carbide product. The gas generation amount of the product is detected by gas evolution, and the gas generation amount reaches 283 L / kg.

[0037] Example 6:

[0038] Using cyanamide waste residue as the calcium source, the calcium source and by-product carbon powder are mixed at mass ratios of 2:1, 3:1, 4:1, and 5:1 respectively through the binder potassium lignosulfonate. The dosage of the binder accounts for 5 wt% of the sum of the calcium source and by-product carbon dosage, and a mixed raw material is prepared. Each mixed raw material is pressed into shape and then dried to obtain a sample raw material. Each sample is placed in a reaction chamber and heated to 1500 °C under N2 atmosphere and kept warm for 60 min to synthesize calcium carbide product.

[0039] After the hydrolysis reaction of all the calcium carbide products obtained above to release acetylene gas, the by-product calcium carbide slag slurry produced is collected centrally, and after filtration and drying, dry calcium carbide slag is obtained. This calcium carbide slag has no ash content and is mainly composed of calcium hydroxide, which can be directly used as the calcium source for calcium carbide production to achieve recycling. Using the obtained calcium carbide slag as the calcium source, it is mixed with the by-product carbon powder in a mass ratio of 4:1 through the binder potassium lignosulfonate. The dosage of the binder accounts for 5 wt% of the sum of the calcium source and the by-product carbon dosage to prepare a mixed raw material. After the mixed raw material is pressed into shape, it is dried to obtain a sample raw material. The sample is placed in the reaction chamber, N2 is introduced into the reaction chamber and heated to 1500 °C for 60 min to obtain a calcium carbide product. After the gas evolution of the product is detected, its gas evolution reaches 271 L / kg.

[0040] The calcium carbide products prepared by the method of the present invention all meet the requirements for qualified calcium carbide in the national standard (GB10665-2004) (gas evolution ≥ 260 L / kg).

[0041] In summary, since the by-product carbon from methane pyrolysis to acetylene is nanoscale dispersed and has a high degree of graphitization, it cannot be converted into calcium carbide by existing calcium carbide synthesis methods and equipment. Through the method of the present invention, the nanoscale by-product carbon is bonded together by a binder with a catalytic effect, and the metal ions in the binder can catalyze the reaction to occur and promote the formation of calcium carbide, solving the problem of resource utilization of the by-product carbon.

[0042] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A method for preparing calcium carbide by using by - product carbon produced from the thermal cracking of methane to produce acetylene, characterized in that, Comprising: Mixing the by - product carbon from methane pyrolysis to acetylene, a calcium source, and a catalytic binder, pressing into shape, drying, and then heating in an inert atmosphere to obtain calcium carbide; The binder includes at least one of potassium humate, sodium humate, calcium humate, magnesium humate, calcium carboxymethyl cellulose, sodium carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium lignosulfonate, potassium lignosulfonate, magnesium lignosulfonate, and calcium lignosulfonate.

2. The method according to claim 1, wherein The calcium source includes one or a mixture of calcium carbonate, calcium oxide, calcium hydroxide, cyanamide waste residue, and carbide slag.

3. The method according to claim 1, characterized in that The mass ratio of the calcium source to the by - product carbon from methane pyrolysis to acetylene is 2 - 5:

1.

4. The method according to claim 1, characterized in that, Based on the total mass of the calcium source and the by - product carbon from methane pyrolysis to acetylene being 100%, the mass proportion of the binder is 1% - 20%.

5. The method according to claim 1, characterized in that, The inert atmosphere is one or a combination of nitrogen and argon.

6. The method according to claim 1, characterized in that, The heating temperature is 1000 - 1800 °C.

7. The method according to claim 1, characterized in that, The heating time is 30 - 90 min.

8. The method according to claim 1, wherein The calcium carbide has no ash content and the gas generation amount is between 270 - 295 L / kg.

9. The method according to claim 1 or 8, characterized in that, The method further includes a calcium carbide slag recycling process, which includes: using the calcium carbide slag generated after hydrolyzing the calcium carbide to obtain acetylene gas as part or all of the calcium source, mixing it with the by - product carbon from methane pyrolysis to acetylene and a catalytic binder, pressing into shape, drying, and then heating in an inert atmosphere to obtain calcium carbide.

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