Mixture for producing calcium carbide and preparation method of calcium carbide

Abstract

The invention provides a mixture for producing calcium carbide and a preparation method of the calcium carbide. The mixture for producing the calcium carbide comprises a calcium-containing raw material, a carbon-containing raw material and auxiliaries, and the auxiliaries comprise calcium fluoride, lanthanum fluoride and calcium molybdate. According to the invention, calcium fluoride is used as a mineralization basis, so that stable crystal lattices of calcium oxide are effectively destroyed; by virtue of efficient segregation of La < 3 + > at a crystal boundary, the introduced lanthanum fluoride is cooperated with calcium fluoride, so that the interface energy and the system melting point between reactants are further remarkably reduced, and the synthesis initial temperature of the calcium carbide is reduced by virtue of the calcium fluoride-lanthanum fluoride synergistic melting reduction effect; the problem that the reaction temperature of a traditional process is too high is fundamentally solved, and the electric energy consumption is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of calcium carbide production, and more specifically to a mixture for producing calcium carbide and a method for preparing calcium carbide. Background Technology

[0002] Calcium carbide (CaC2) is an indispensable basic raw material in modern chemical industry, widely used in acetylene chemical processing, metal smelting, and organic synthesis. Currently, the industrial production of calcium carbide commonly involves the reduction reaction of calcium oxide (CaO) with carbonaceous materials (such as coke and anthracite) in an electric arc furnace at ultra-high temperatures of 2000-2200℃. The core reaction is: CaO + 3C → CaC2 + CO. This process is inherently extremely energy-intensive, placing stringent requirements on the refractory materials used in the equipment and resulting in significant production costs and environmental impact.

[0003] To alleviate the aforementioned problems, introducing additives into the raw materials for calcium carbide refining has become a key area for technological improvement in the industry. Among these, calcium fluoride (CaF2, fluorite), as the most widely used traditional mineralizer, improves the mass transfer conditions and flowability of materials in the furnace to some extent by disrupting the calcium oxide crystal structure and forming eutectic compounds with impurities such as silica and alumina in the system. However, its cooling effect has reached its limit, making it difficult to achieve significant breakthroughs in reaction temperature and contributing limitedly to further reductions in energy consumption. More importantly, calcium fluoride mainly acts on physical mass transfer processes, with little effect on accelerating the interfacial chemical reaction rate between carbon raw materials and oxygen ions—that is, improving reaction kinetics. This makes it difficult to effectively increase the calcium carbide formation rate, thus restricting further increases in production intensity. Summary of the Invention

[0004] To address the shortcomings of existing technologies and solve the aforementioned problems, this paper proposes a mixture for producing calcium carbide and a method for preparing calcium carbide, and provides the following technical solution: A mixture for producing calcium carbide, the mixture comprising calcium-containing raw materials, carbon-containing raw materials, and additives, wherein the additives include calcium fluoride, lanthanum fluoride, and calcium molybdate.

[0005] Furthermore, the mass ratio of calcium fluoride, lanthanum fluoride, and calcium molybdate is 10:1-5:2-3.

[0006] Furthermore, the mass ratio of calcium fluoride, lanthanum fluoride, and calcium molybdate is 10:1.5:2.5.

[0007] Furthermore, by weight, the raw materials comprise 50-60 parts of calcium-containing raw materials, 40-100 parts of carbon-containing raw materials, 1-3 parts of calcium fluoride, 0.1-0.4 parts of lanthanum fluoride, and 0.4-0.6 parts of calcium molybdate.

[0008] Furthermore, by weight, the raw materials comprise 55 parts of calcium-containing raw materials, 60 parts of carbon-containing raw materials, 2 parts of calcium fluoride, 0.3 parts of lanthanum fluoride, and 0.5 parts of calcium molybdate.

[0009] Furthermore, the calcium-containing raw material is at least one of calcium carbonate, calcium oxide, calcium hydroxide, or carbide slag, and the carbon-containing raw material is at least one of coke or semi-coke.

[0010] This application also provides a method for preparing calcium carbide using the above-mentioned mixture for producing calcium carbide as a raw material.

[0011] Furthermore, the preparation method of calcium carbide using the mixture used for calcium carbide production as raw material is as follows: after mixing the mixture, place it in a calcium carbide furnace and smelt it at a temperature of 1400-1600℃ for 10-20 minutes to obtain calcium carbide.

[0012] Furthermore, the particle size of the carbon-containing and calcium-containing raw materials is 5-30 mm, respectively.

[0013] Furthermore, the process includes a raw material drying step before the calcium carbide raw material is mixed.

[0014] Due to the adoption of the above technical solutions, the beneficial technical effects of the present invention are as follows: 1. In this invention, calcium fluoride serves as the mineralization basis, effectively disrupting the stable lattice of calcium oxide; while the introduced lanthanum fluoride, due to its La content... 3+ The efficient segregation at the grain boundaries, in synergy with calcium fluoride, further significantly reduces the interfacial energy between reactant phases and the melting point of the system. This synergistic melting point reduction effect of calcium fluoride and lanthanum fluoride lowers the starting temperature of calcium carbide synthesis, fundamentally solving the problem of excessively high reaction temperature in traditional processes and greatly reducing energy consumption.

[0015] 2. This invention also introduces calcium molybdate, which constructs a dynamic "oxidation-reduction" catalytic cycle (Mo) at high temperature. 6+ / Mo 4 + It can efficiently activate the surface of CO, the gaseous product of the reaction, and carbon raw materials, greatly promoting the migration and transfer of carbon atoms. This kinetic enhancement mechanism is perfectly complementary to the mass transfer optimization mechanism of calcium fluoride-lanthanum fluoride. The three work together to effectively solve the problem of slow reaction kinetics in the existing technology, thereby obtaining a higher calcium carbide yield per unit time and significantly improving production efficiency. Detailed Implementation

[0016] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Based on the embodiments in this application, other similar embodiments obtained by those skilled in the art without creative effort should all fall within the scope of protection of this application.

[0017] A mixture for producing calcium carbide comprises calcium-containing raw materials, carbon-containing raw materials, and additives, wherein the additives include calcium fluoride, lanthanum fluoride, and calcium molybdate. Calcium fluoride, as a basic mineralizing agent, effectively disrupts the crystal lattice of calcium oxide and forms a eutectic. The addition of lanthanum fluoride utilizes its La... 3+ The high tendency for segregation at grain boundaries further reduces the interfacial energy between reactant phases, resulting in a strong synergistic effect of lowering the melting point with calcium fluoride. This ternary composite additive of the present invention can lower the starting temperature of calcium carbide synthesis, thereby significantly reducing the energy consumption of the smelting process. Simultaneously, under a high-temperature reducing atmosphere, the molybdenum ions (Mo) in calcium molybdate... 6+ / Mo 4+ This constitutes a dynamic "oxidation-reduction" catalytic cycle, which can efficiently activate the surface of carbon monoxide and carbon raw materials, greatly accelerating the migration and transfer of carbon atoms to the reaction interface. This mechanism complements the mass transfer promoting effect of calcium fluoride and lanthanum fluoride, achieving a higher calcium carbide yield in the same time period and effectively improving production efficiency. Under the high-temperature reducing atmosphere of the calcium carbide furnace, some Mo... 6+ (Molybdenum in molybdate) will be reduced to lower valence molybdenum species (such as Mo). 4 + These molybdenum molecules in different valence states form a dynamic redox pair at the reaction interface. This redox pair can efficiently activate CO molecules (the gaseous product of the calcium carbide reaction). The activated CO can more effectively "extract" carbon atoms from the surface of carbon materials to generate CO2 (gas phase), while the newly generated active carbon species or carbon vacancies have extremely high reactivity. This process can be simplified to: C (inert) + [Mo] 6+ / Mo 4+ → C (highly reactive) + CO2. Calcium molybdate establishes a highly efficient atomic transport channel between the carbon surface and the reaction interface, a novel function that CaF2 completely lacks. In this invention, calcium fluoride serves as the mineralization basis, effectively disrupting the stable lattice of calcium oxide; while the introduced lanthanum fluoride, with its La... 3+ The efficient segregation at grain boundaries, synergistically with calcium fluoride, significantly reduces the interfacial energy and melting point of the reactant phases. This synergistic melting point reduction effect of calcium fluoride and lanthanum fluoride lowers the starting temperature for calcium carbide synthesis, fundamentally solving the problem of excessively high reaction temperatures in traditional processes and drastically reducing energy consumption. This invention also introduces calcium molybdate, which constructs a dynamic oxidation-reduction catalytic cycle (Mo...) at high temperatures.6+ / Mo 4+ It can efficiently activate the surface of CO, the gaseous product of the reaction, and carbon raw materials, greatly promoting the migration and transfer of carbon atoms. This kinetic enhancement mechanism is perfectly complementary to the mass transfer optimization mechanism of calcium fluoride-lanthanum fluoride. The three work together to effectively solve the problem of slow reaction kinetics in the existing technology, thereby obtaining a higher calcium carbide yield per unit time and significantly improving production efficiency.

[0018] This application also provides a method for preparing calcium carbide, wherein the method involves mixing a mixture and placing it in a calcium carbide furnace, then smelting it at a temperature of 1400-1600℃ to obtain calcium carbide. The particle size of the carbon-containing and calcium-containing raw materials in the mixture is 5-30 mm, respectively.

[0019] Traditional calcium carbide production processes typically require crushing raw materials to a small particle size range to ensure sufficient reaction kinetics. This invention, through the synergistic effect of the aforementioned ternary composite additives, ensures that even with coarser raw material particle sizes of 5-30 mm, the reactants can still react fully and efficiently within a relatively low temperature range of 1400-1600℃. This effect is mainly attributed to the dual role of the additive system: calcium fluoride and lanthanum fluoride significantly improve interfacial mass transfer conditions through a deep eutectic effect, while the catalytic cycle constructed by calcium molybdate greatly enhances the intrinsic reaction kinetics. This technology offers significant industrial application value. On the one hand, it reduces the energy consumption and cost requirements of the raw material crushing process, improving economic efficiency; on the other hand, the coarser raw material particle size effectively improves the permeability of the furnace charge, ensuring the stability and continuity of calcium carbide furnace operation, while providing crucial support for achieving low-temperature energy-saving smelting.

[0020] Example 1 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 15-30 mm. 60 parts semi-coke, 55 parts quicklime, 2 parts calcium fluoride, 0.3 parts lanthanum fluoride, and 0.5 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a sealed conveyor system. Heating was applied, and the smelting temperature was controlled at 1500℃ for a reaction time of 15 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 88.11% calcium carbide and had a gas evolution rate of 314 L / kg.

[0021] Example 2 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 15-30 mm. 100 parts semi-coke, 60 parts quicklime, 3 parts calcium fluoride, 0.4 parts lanthanum fluoride, and 0.6 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a sealed conveyor system. Heating was applied, and the smelting temperature was controlled at 1500℃ for a reaction time of 15 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 85.75% calcium carbide and had a gas evolution rate of 307 L / kg.

[0022] Example 3 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 15-30 mm. 40 parts semi-coke, 50 parts quicklime, 1 part calcium fluoride, 0.1 parts lanthanum fluoride, and 0.4 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a sealed conveyor system. Heating was applied, and the smelting temperature was controlled at 1500℃ for a reaction time of 15 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 86.01% calcium carbide and had a gas evolution rate of 308 L / kg.

[0023] Example 4 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 5-15 mm. 60 parts semi-coke, 55 parts quicklime, 2 parts calcium fluoride, 0.3 parts lanthanum fluoride, and 0.5 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a closed conveyor system. Heating was applied, and the smelting temperature was controlled at 1500℃ for a reaction time of 10 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 86.67% calcium carbide and had a gas evolution rate of 305 L / kg.

[0024] Example 5 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 15-30 mm. 60 parts semi-coke, 55 parts quicklime, 2 parts calcium fluoride, 0.3 parts lanthanum fluoride, and 0.5 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a sealed conveyor system. Heating was applied, and the smelting temperature was controlled at 1400℃ for a reaction time of 20 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 85.94% calcium carbide and had a gas evolution rate of 305 L / kg.

[0025] Example 6 Semi-coke, calcium fluoride, lanthanum fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. These components were then pulverized to a particle size of 15-30 mm. 60 parts semi-coke, 55 parts quicklime, 2 parts calcium fluoride, 0.3 parts lanthanum fluoride, and 0.5 parts calcium molybdate were added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a sealed conveyor system. Heating was applied, and the smelting temperature was controlled at 1600℃ for a reaction time of 12 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 86.11% calcium carbide and had a gas evolution rate of 309 L / kg.

[0026] Comparative Example 1 Semi-coke was dried by indirect heating until its moisture content was below 1%. The semi-coke and quicklime were then pulverized to a particle size of 15-30 mm. 60 parts of semi-coke and 55 parts of quicklime were then added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a closed conveyor system. Heating was applied, and the smelting temperature was controlled at 2100℃ for a reaction time of 60 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 80.36% calcium carbide and had a gas evolution rate of 286 L / kg.

[0027] Comparative Example 2 Semi-coke, calcium fluoride, and calcium molybdate were dried separately by indirect heating until the moisture content was below 1%. The semi-coke, quicklime, calcium fluoride, and calcium molybdate were then pulverized to a particle size of 15-30 mm. 60 parts of semi-coke, 55 parts of quicklime, 2 parts of calcium fluoride, and 0.5 parts of calcium molybdate were then added to a twin-shaft mixer and mixed for 30 minutes until homogeneous, yielding the mixture for calcium carbide production. This mixture was then fed into a closed calcium carbide furnace via a closed conveyor system. Heating was applied, and the smelting temperature was controlled at 1700℃ for a reaction time of 30 minutes. After the reaction, the molten calcium carbide was discharged through the furnace outlet, cooled, and crushed to obtain the finished calcium carbide. The finished calcium carbide contained 82.86% calcium carbide and had a gas evolution rate of 293 L / kg.

[0028] Example 1 utilizes an optimized ternary composite additive system of calcium fluoride-lanthanum fluoride-calcium molybdate. At a low temperature of 1500℃, a reaction time of only 15 minutes yields high-quality calcium carbide with a calcium carbide content of 88.11% and a gas evolution rate of 314 L / kg, achieving an optimal balance between low-temperature efficiency and product quality. Examples 2-5, under different raw material ratios, particle sizes, and process parameters, although their product quality is slightly inferior to Example 1, all maintain a calcium carbide content above 85% and a gas evolution rate exceeding 305 L / kg, demonstrating significantly superior overall performance compared to the comparative examples. Comparative Example 1, without any additives, requires a reaction time of 60 minutes at 2100℃, resulting in a calcium carbide content of only 80.36% and a gas evolution rate of 286 L / kg, proving that traditional processes are energy-intensive, inefficient, and limited in product quality. Comparative Example 2, using only a binary system of calcium fluoride and calcium molybdate, reduced the reaction temperature to 1700°C and shortened the reaction time to 30 minutes, but the product quality (82.86%) was far inferior to any of the examples, indicating that the lack of lanthanum fluoride's synergistic effect prevented the achievement of a low-temperature, high-efficiency reaction. The additive system of this invention is particularly suitable for coarser raw materials, possessing unique advantages such as reduced crushing energy consumption and improved furnace charge permeability. These comparative results demonstrate that only through the synergistic effect of calcium fluoride, lanthanum fluoride, and calcium molybdate can breakthroughs in reaction temperature, reaction time, and raw material adaptability be achieved simultaneously; the absence of any component or deviation in the process will prevent the attainment of the desired results.

[0029] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A mixture for producing calcium carbide, characterized in that, The mixture comprises calcium-containing raw materials, carbon-containing raw materials, and additives, wherein the additives include calcium fluoride, lanthanum fluoride, and calcium molybdate.

2. The mixture for producing calcium carbide according to claim 1, characterized in that, The mass ratio of calcium fluoride, lanthanum fluoride, and calcium molybdate is 10:1-5:2-3.

3. The mixture for producing calcium carbide according to claim 1, characterized in that, The mass ratio of calcium fluoride, lanthanum fluoride, and calcium molybdate is 10:1.5:2.

5.

4. The mixture for producing calcium carbide according to claim 1, characterized in that, By weight, the raw materials comprise 50-60 parts of calcium-containing raw materials, 40-100 parts of carbon-containing raw materials, 1-3 parts of calcium fluoride, 0.1-0.4 parts of lanthanum fluoride, and 0.4-0.6 parts of calcium molybdate.

5. The mixture for producing calcium carbide according to claim 1, characterized in that, By weight, the raw materials comprise 55 parts calcium-containing raw materials, 60 parts carbon-containing raw materials, 2 parts calcium fluoride, 0.3 parts lanthanum fluoride, and 0.5 parts calcium molybdate.

6. The mixture for producing calcium carbide according to claim 1, characterized in that, The calcium-containing raw material is at least one of calcium carbonate, calcium oxide, calcium hydroxide, or carbide slag, and the carbon-containing raw material is at least one of coke or semi-coke.

7. A method for preparing calcium carbide, characterized in that, Calcium carbide is prepared using the mixture for producing calcium carbide as described in any one of claims 1-6 as raw material.

8. The method for preparing calcium carbide according to claim 7, characterized in that, The preparation method is as follows: the mixture for producing calcium carbide is mixed and placed in a calcium carbide furnace, and smelted at a temperature of 1400-1600℃ for 10-20 minutes to obtain calcium carbide.

9. The method for preparing calcium carbide according to claim 7, characterized in that, The particle size of carbon-containing and calcium-containing raw materials is 5-30 mm.

10. The method for preparing calcium carbide according to claim 7, characterized in that, The mixture used for producing calcium carbide also includes a drying step before mixing.