Application of coal ash in reduction of phosphate rock to produce yellow phosphorus, method for reduction of phosphate rock to produce yellow phosphorus

Abstract

The present application relates to the comprehensive field of mineral resources and the technical field of energy saving and consumption reduction, and particularly relates to application of coal ash in reduction of phosphate ore to obtain yellow phosphorus and a method for reduction of phosphate ore to obtain yellow phosphorus. The method comprises: in a non-oxidizing atmosphere, reduction reaction is carried out on a mixture containing phosphate ore, a reducing agent and a flux, yellow phosphorus furnace gas obtained is subjected to water washing and cooling, so that phosphorus steam in the yellow phosphorus furnace gas is stored in water in liquid or solid form, and yellow phosphorus is obtained; wherein the flux is selected from coal ash and optional silica; wherein the temperature of the reduction reaction is not lower than 1300 DEG C. The method provided by the present application can effectively improve the reduction rate of phosphate ore and shorten the reduction reaction time; the method realizes recycling utilization of coal ash resources.

Description

Technical Field

[0001] This invention relates to the fields of comprehensive mineral resources and energy conservation and consumption reduction, specifically to the application of coal ash slag in the reduction of phosphate rock to produce yellow phosphorus, and a method for reducing phosphate rock to produce yellow phosphorus. Background Technology

[0002] Yellow phosphorus is a raw material for the production of fine phosphate chemicals and high-quality phosphoric acid. Currently, the electric furnace method is the only industrial method for producing yellow phosphorus. This involves mixing phosphate rock, silica, and coke in a specific ratio and heating the mixture to 1400-1500℃ in an electric furnace using electrodes, reducing the phosphorus in the phosphate rock to elemental phosphorus. The calcium fluorophosphate in the phosphate rock is then reacted at high temperatures with silica as a flux and carbon as a reducing agent to produce phosphorus vapor and carbon monoxide. The phosphorus vapor is then washed with water and cooled to obtain yellow phosphorus. Currently, in addition to the traditional additive silica, some researchers have tried adding Al₂O₃, MgO, potassium-containing silicate minerals, and alkali metal salts to lower the melting temperature of the reduced phosphate rock, thereby improving the mass transfer efficiency between the phosphate rock and carbon. However, due to the limited effectiveness and economic issues, few companies have adopted this method.

[0003] Currently, coal ash is mainly used as a cementitious admixture or concrete additive, but its utilization is difficult due to its complex processing technology. Depending on the coal quality, burning one ton of coal produces approximately 100-300 kg of coal ash. Most of the generated coal ash is transported to fixed sites for centralized storage, often resulting in spillage and dust pollution during transport. Furthermore, the coal ash stored on these sites oxidizes due to prolonged contact with air, leading to spontaneous combustion and causing excessive CO concentrations in the surrounding area, thus endangering human health.

[0004] In summary, to address the problems of high energy consumption, low phosphate rock reduction rate, and environmental pollution caused by coal ash and slag stockpiling in the production of yellow phosphorus by electric furnace method, this invention discloses a method for producing yellow phosphorus by using coal ash and slag as a flux to enhance the reduction of phosphate rock. This method not only enables the resource utilization of coal ash and slag but also improves the phosphate rock reduction rate and significantly reduces the energy consumption of yellow phosphorus production. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical problems and provide an application of coal ash in the reduction of phosphate rock to produce yellow phosphorus, and a method for reducing phosphate rock to produce yellow phosphorus. This method effectively improves the reduction rate of phosphate rock and shortens the reduction time. At the same time, this method also realizes the resource utilization of coal ash.

[0006] To achieve the above objectives, the first aspect of the present invention provides the application of coal ash residue in the reduction of phosphate rock to produce yellow phosphorus.

[0007] Preferably, the coal ash contains 35-50 wt% SiO2, 10-35 wt% Al2O3, 5-20 wt% Fe2O3, 0.5-10 wt% MgO, 3-15 wt% CaO, and 10-25 wt% C.

[0008] The second aspect of the present invention provides a method for producing yellow phosphorus by reducing phosphate rock, the method comprising: in a non-oxidizing atmosphere, carrying out a reduction reaction of a mixture containing phosphate rock, a reducing agent and a flux, and cooling the resulting yellow phosphorus furnace gas by washing with water, so that the phosphorus vapor in the yellow phosphorus furnace gas is stored in water in liquid or solid form, thereby obtaining yellow phosphorus;

[0009] The flux is selected from coal ash and optionally silica;

[0010] The temperature of the reduction reaction is not lower than 1300℃.

[0011] Preferably, the method includes the following steps:

[0012] (1) The phosphate rock, reducing agent and flux are dried separately and then mixed to obtain the mixture with a water content ≤0.2wt%;

[0013] (2) In a non-oxidizing atmosphere, the mixture is subjected to the reduction reaction, and the resulting yellow phosphorus furnace gas is subjected to water washing and cooling to obtain the yellow phosphorus.

[0014] Preferably, the molar ratio of C content in the reducing agent to P2O5 content in the phosphate rock is ≥5:1, and more preferably 5.5-7:1.

[0015] Preferably, the weight ratio of coal ash and silica in the flux is 20-100:0-80, more preferably 80-100:0-20.

[0016] Preferably, the amounts of phosphate rock, coal ash, and optional silica are such that the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.6-0.95, more preferably 0.7-0.9, and even more preferably 0.75-0.85.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention uses coal ash slag to reduce phosphate rock to produce yellow phosphorus. Compared with traditional silica, under the same conditions, it can effectively improve the reduction rate of phosphate rock, up to 98.9%. At the same time, since coal ash slag contains residual carbon, it saves the amount of reducing agent added during the phosphate rock reduction process.

[0019] (2) The method for producing yellow phosphorus by reducing phosphate rock provided by the present invention uses coal ash and optional silica as flux. In particular, by controlling the weight ratio of coal ash and silica in the flux, the reduction rate of phosphate rock can be improved more effectively, the reduction reaction time can be shortened, the energy consumption of the reduction reaction can be reduced, the amount of reducing agent added can be reduced, and thus the production cost of yellow phosphorus can be reduced. At the same time, the method solves the pollution problem of coal ash and realizes the resource recycling, which has the characteristics of energy saving and environmental protection. Attached Figure Description

[0020] Figure 1 This is a graph showing the relationship between phosphate rock reduction rate and reaction temperature in different systems of Example 1 and Comparative Example 1.

[0021] Figure 2 This is a graph showing the relationship between phosphate rock reduction rate and reaction time in different systems of Example 3 and Comparative Example 3;

[0022] Figure 3 This is a graph showing the relationship between the reduction rate of phosphate rock and the acidity value of the mixture in different systems of Example 4 and Comparative Example 4; wherein the acidity value of the mixture is expressed as the mass ratio of (SiO2+Al2O3) to (CaO+MgO) in the mixture. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of this invention provides the application of coal ash residue in the reduction of phosphate rock to produce yellow phosphorus.

[0025] The inventors of this invention have discovered that SiO2, Al2O3, Fe2O3, and MgO play a crucial role as fluxes in the carbothermic reduction of phosphate rock. Adding fluxes can lower the reduction reaction temperature of yellow phosphorus, thereby reducing energy consumption in yellow phosphorus production. Coal ash contains abundant components (i.e., SiO2 content 35-50 wt%, Al2O3 content 10-35 wt%, Fe2O3 content 5-20 wt%, MgO content 0.5-10 wt%, CaO content 3-15 wt%, and C content 10-25 wt%). Using coal ash as a flux instead of silica can effectively improve the phosphate rock reduction rate, reduce energy consumption, and achieve efficient utilization of coal ash resources.

[0026] In this invention, unless otherwise specified, the waste residue produced after coal combustion is referred to as coal ash, the main components of which are SiO2, Al2O3, Fe2O3, MgO, CaO, C, etc.

[0027] In some embodiments of the present invention, preferably, the coal ash contains 35-50 wt% SiO2, 10-35 wt% Al2O3, 5-20 wt% Fe2O3, 0.5-10 wt% MgO, 3-15 wt% CaO, and 10-25 wt% C.

[0028] In this invention, unless otherwise specified, the content of each component in coal ash is determined using the method specified in GB / T 1574—2007.

[0029] The second aspect of the present invention provides a method for producing yellow phosphorus by reducing phosphate rock, the method comprising: in a non-oxidizing atmosphere, carrying out a reduction reaction of a mixture containing phosphate rock, a reducing agent and a flux, and cooling the resulting yellow phosphorus furnace gas by washing with water, so that the phosphorus vapor in the yellow phosphorus furnace gas is stored in water in liquid or solid form to obtain yellow phosphorus;

[0030] The flux is selected from coal ash and optionally silica;

[0031] The temperature of the reduction reaction is not lower than 1300℃.

[0032] In this invention, unless otherwise specified, the mixture containing phosphate rock, reducing agent, and flux refers to a mixture that may contain other components besides phosphate rock, reducing agent, and flux. Preferably, the mixture consists of phosphate rock, reducing agent, and flux.

[0033] In some embodiments of the present invention, preferably, the method includes the following steps:

[0034] (1) The phosphate rock, reducing agent and flux are dried separately and then mixed to obtain the mixture with a water content ≤0.2wt%;

[0035] (2) In a non-oxidizing atmosphere, the mixture is subjected to the reduction reaction, and the resulting yellow phosphorus furnace gas is subjected to water washing and cooling to obtain the yellow phosphorus.

[0036] In some embodiments of the present invention, preferably, when the water content in the phosphate rock, reducing agent and flux is >0.2wt%, the water content in the mixture is ≤0.2wt% by calcination or other heating methods.

[0037] In this invention, the mixing is intended to ensure that the phosphate rock, reducing agent, and flux are mixed evenly. Preferably, in step (1), the mixing conditions include a temperature of 0-60°C, more preferably 20-30°C.

[0038] In some embodiments of the present invention, the molar ratio of the C content in the reducing agent to the P2O5 content in the phosphate rock is ≥5:1, for example, 5.5:1, 6:1, 7:1, or any value within any range of any two values, preferably 5.5-7:1, and most preferably 6:1. When the molar ratio is less than 5:1, due to the presence of iron and carbonates in the phosphate rock, some carbon is consumed, resulting in incomplete reduction of P2O5 in the phosphate rock, an increase in the P2O5 content in the residue, a decrease in the phosphate rock reduction rate, and a decrease in the yellow phosphorus yield. When the molar ratio is too high, there will be too much reducing agent, resulting in waste of raw materials, and it will also promote the occurrence of side reactions, increase power consumption, reduce the thermal efficiency of the electric furnace, and lead to an increase in phosphorus power consumption.

[0039] In this invention, unless otherwise specified, the flux selected from coal ash and optionally silica means that the flux can be coal ash or a mixture of coal ash and silica.

[0040] In some embodiments of the present invention, preferably, the weight ratio of coal ash and silica in the flux is 20-100:0-80, for example, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, 95:5, 100:0, and any value within any range of any two values, preferably 80-100:0-20. Using these preferred conditions is more conducive to improving the reduction rate of phosphate rock, especially under the same conditions.

[0041] In some embodiments of the present invention, the amounts of phosphate rock, coal ash, and optional silica satisfy the following: the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.6-0.95, for example, 0.6, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, and any value within the range of any two values, preferably 0.7-0.9, more preferably 0.75-0.85, and most preferably 0.8. When the mass ratio is too high or too low, it will result in a high melting point, low electric furnace efficiency, more side reactions, and a decrease in phosphorus yield, which is detrimental to the operation of the electric furnace.

[0042] In this invention, unless otherwise specified, the amounts of phosphate rock, coal ash, and optional silica satisfy the following: the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.6-0.95, which refers to the mass ratio of (SiO2+Al2O3) to (CaO+MgO) in the amounts of phosphate rock, coal ash, and silica.

[0043] In this invention, unless otherwise specified, the amounts of phosphate rock, coal ash, and optional silica satisfy the following: the mass ratio parameter of (SiO2+Al2O3) to (CaO+MgO) refers to the quaternary acidity coefficient.

[0044] In this invention, the phosphate rock mainly contains P2O5, CaO, MgO, SiO2, and Al2O3. Preferably, the phosphate rock contains 20-30 wt% P2O5, 30-40 wt% CaO, 1-10 wt% MgO, 4-25 wt% SiO2, and 1-5 wt% Al2O3.

[0045] In some embodiments of the present invention, preferably, the reducing agent is selected from at least one of coke, white coal and lignite; more preferably, the reducing agent is coke.

[0046] In some embodiments of the present invention, preferably, the coal ash contains 35-50 wt% SiO2, 10-35 wt% Al2O3, 5-20 wt% Fe2O3, 0.5-10 wt% MgO, 3-15 wt% CaO, and 10-25 wt% C.

[0047] In some embodiments of the present invention, preferably, the silica contains 85-98 wt% SiO2, 0.1-0.5 wt% Al2O3, 0.1-1 wt% Fe2O3, and 0.1-0.5 wt% CaO.

[0048] In this invention, in step (2), the reduction reaction aims to reduce the calcium fluorophosphate in the phosphate rock in the mixture to obtain yellow phosphorus furnace gas containing phosphorus vapor and carbon monoxide under the action of reducing agent and flux; at the same time, the yellow phosphorus furnace gas is washed and cooled with water so that the phosphorus vapor in the yellow phosphorus furnace gas dissolves in water to obtain solid elemental yellow phosphorus.

[0049] In some embodiments of the present invention, preferably, the conditions for the reduction reaction include: a temperature of 1300-1700℃, for example, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, or any value within the range of any two values, preferably 1400-1700℃; and a time of 10-200 min, for example, 10 min, 20 min, 40 min, 60 min, 80 min, 100 min, 150 min, 200 min, or any value within the range of any two values, preferably 20-100 min. Using these preferred reaction conditions is more conducive to improving the reduction rate of phosphate rock.

[0050] In one specific embodiment of the present invention, the reduction reaction is carried out in a reactor, wherein the reaction temperature is ≥1300℃, preferably 1300-1700℃, more preferably 1400-1700℃; and the reaction time is 10-200 min, preferably 20-100 min.

[0051] In some embodiments of the present invention, preferably, in step (2), the conditions for water washing and cooling include: a temperature of 0-80°C, preferably 20-50°C.

[0052] According to a particularly preferred embodiment of the present invention, a method for producing yellow phosphorus by reducing phosphate rock, the method comprising:

[0053] (1) The phosphate rock, reducing agent and flux are dried separately and then mixed to obtain a mixture with a water content ≤0.2wt%;

[0054] (2) In a non-oxidizing atmosphere, the mixture is subjected to a reduction reaction, and the resulting yellow phosphorus furnace gas is washed and cooled with water so that the phosphorus vapor in the yellow phosphorus furnace gas is stored in water in liquid or solid form to obtain yellow phosphorus;

[0055] The flux is selected from coal ash and optional silica, and the weight ratio of coal ash to silica is 80-100:0-20.

[0056] The amounts of phosphate rock, coal ash, and optional silica are such that the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.75-0.85.

[0057] The molar ratio of C content in the reducing agent to P2O5 content in the phosphate rock is 6:1.

[0058] The coal ash contains 35-50 wt% SiO2, 10-35 wt% Al2O3, 5-20 wt% Fe2O3, 0.5-10 wt% MgO, 3-15 wt% CaO, and 10-25 wt% C.

[0059] The conditions for the reduction reaction include: a temperature of 1400-1700℃ and a time of 20-100 min.

[0060] The present invention will be described in detail below through embodiments.

[0061] The phosphate rock contained 25.16 wt% P2O5, 37.49 wt% CaO, 2.31 wt% MgO, 20.11 wt% SiO2, and 1.24 wt% Al2O3.

[0062] The silica contains 94.25 wt% SiO2.

[0063] The coal ash residue contains 46.94 wt% SiO2, 22.44 wt% Al2O3, 12.23 wt% Fe2O3, 5.56 wt% MgO, 9.19 wt% CaO, and 15.3 wt% C.

[0064] Example 1

[0065] (1) The above-mentioned phosphate rock, coke and coal ash are mixed to obtain a mixture with a water content of 0.15 wt%; wherein the molar ratio of the above-mentioned coke calculated as C and the above-mentioned phosphate rock calculated as P2O5 is 6:1, and the amount of the above-mentioned phosphate rock and the above-mentioned coal ash satisfies the following: the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.8;

[0066] (2) In an oxygen-free atmosphere, the above mixture was placed in a tube furnace and reacted for 20 min at temperatures of 1300℃, 1400℃, 1500℃, 1600℃ and 1700℃ respectively. The resulting yellow phosphorus furnace gas was washed with water and cooled to 25℃. The phosphorus content of the residue was analyzed and the reduction rate of phosphate rock was calculated. The experimental data are listed in Table 1.

[0067] The relationship between phosphate rock reduction rate and reaction temperature in different systems of Example 1 and Comparative Example 1 is shown in the graph below. Figure 1 As shown, by Figure 1 It can be seen that when the reaction temperature is 1700℃, compared with the use of silica in Comparative Example 1, the reduction rate of phosphate rock in Example 1 is increased by 2.61% when coal ash is used as a flux. When the reaction temperature is 1400℃, compared with the use of silica in Comparative Example 1, the reduction rate of phosphate rock in Example 1 is increased by 40% when coal ash is used as a flux.

[0068] Comparative Example 1

[0069] The method is the same as in Example 1, except that in step (1),

[0070] The above-mentioned coal ash was replaced with the above-mentioned silica, and all other conditions remained the same. The experimental data are listed in Table 1.

[0071] Table 1

[0072]

[0073] As can be seen from the data in Table 1, compared with Comparative Example 1 which uses silica as a flux, the technical solution of Example 1 which uses coal ash as a flux gradually increases the phosphate rock reduction rate as the reaction temperature increases.

[0074] Example 2

[0075] (1) The above-mentioned phosphate rock, coke, coal ash and silica are mixed to obtain a mixture with a water content of 0.15 wt%;

[0076] The weight ratios of coal ash and silica are 20:80, 40:60, 60:40, 80:20, and 100:0, respectively.

[0077] The molar ratio of the coke (calculated as C) to the phosphate rock (calculated as P2O5) is 6:1; the amounts of the phosphate rock, the coal ash, and the silica satisfy the following: the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.8.

[0078] (2) In an oxygen-free atmosphere, the above mixture was placed in a tube furnace and reacted at 1450℃ for 60 min. The resulting yellow phosphorus furnace gas was washed with water and cooled to 25℃. The phosphorus content of the residue was analyzed and the phosphate rock reduction rate was calculated. The experimental data are listed in Table 2.

[0079] Comparative Example 2

[0080] The method is the same as in Example 2, except that in step (1),

[0081] The weight ratio of coal ash and silica was changed to 0:100, with all other conditions remaining the same. The experimental data are listed in Table 2.

[0082] Table 2

[0083]

[0084] Note: 1 - The weight ratio of coal ash and silica in the flux.

[0085] As shown in Table 2, compared with Comparative Example 2, the higher the proportion of coal ash in the flux used in Example 2, the higher the phosphate rock reduction rate.

[0086] Example 3

[0087] (1) The above-mentioned phosphate rock, coke and coal ash are mixed to obtain a mixture with a water content of 0.15wt%;

[0088] The molar ratio of the coke (calculated as C) to the phosphate rock (calculated as P2O5) is 6:1; the amounts of the phosphate rock and the coal ash satisfy the following: the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.8.

[0089] (2) In an oxygen-free atmosphere, the above mixture was placed in a tube furnace and reacted at 1400℃ for 20 min, 40 min, 60 min, 80 min and 100 min respectively. The resulting yellow phosphorus furnace gas was washed with water and cooled to 25℃. The phosphorus content of the residue was analyzed and the phosphate rock reduction rate was calculated. The experimental data are listed in Table 3.

[0090] The relationship between phosphate rock reduction rate and reaction time in different systems of Example 3 and Comparative Example 3 is shown in the following graph. Figure 2 As shown, by Figure 2 It can be seen that when the reaction time is 40 min, compared with Comparative Example 3 using silica, when Example 3 uses coal ash as a flux, the phosphate rock reduction rate is increased by 26.1%; when the reaction time is 100 min, compared with Comparative Example 3 using silica, when Example 3 uses coal ash as a flux, the phosphate rock reduction rate is increased by 12.6%.

[0091] Comparative Example 3

[0092] The method is the same as in Example 3, except that in step (1),

[0093] The above-mentioned coal ash was replaced with the above-mentioned silica, and all other conditions remained the same. The experimental data are listed in Table 3.

[0094] Table 3

[0095]

[0096] As can be seen from the data in Table 3, compared with Comparative Example 3 which uses silica as a flux, the technical solution of Example 3 which uses coal ash as a flux gradually increases the phosphate rock reduction rate as the reaction time increases.

[0097] Example 4

[0098] (1) The above-mentioned phosphate rock, coke and coal ash are mixed to obtain a mixture with a water content of 0.15 wt%;

[0099] The molar ratio of the coke (calculated as C) to the phosphate rock (calculated as P2O5) is 6:1.

[0100] The amounts of the aforementioned phosphate rock and coal ash residue satisfy the following mass ratios: (SiO2+Al2O3) to (CaO+MgO) are 0.7, 0.75, 0.8, 0.85, and 0.9, respectively.

[0101] (2) In an oxygen-free atmosphere, the above mixture was placed in a tube furnace and reacted at 1450℃ for 20 min. The resulting yellow phosphorus furnace gas was washed with water and cooled to 25℃. The phosphorus content of the residue was analyzed and the phosphate rock reduction rate was calculated. The experimental data are listed in Table 4.

[0102] The relationship between the phosphate rock reduction rate and the acidity value of the mixture in different systems of Example 4 and Comparative Example 4 is shown in the following graph. Figure 3 As shown, by Figure 3 It can be seen that, compared with Comparative Example 4, Example 4 uses coal ash as a flux, and at an acidity value of 0.8, the phosphate rock reduction rate is 81.5%, which is 38.4% higher than that of the silica system.

[0103] Comparative Example 4

[0104] The method is the same as in Example 4, except that...

[0105] In step (1), the above-mentioned coal ash residue is replaced with silica;

[0106] In step (2), the mass ratios of silica (calculated as SiO2) and phosphate rock (calculated as CaO) were 0.7, 0.75, 0.8, 0.85, and 0.9, respectively, with the other conditions being the same. The experimental data are listed in Table 4.

[0107] Table 4

[0108]

[0109] Note: 2- The acidity value in the mixture is expressed as the mass ratio of (SiO2+Al2O3) to (CaO+MgO) in the mixture.

[0110] As shown in Table 4, compared with Comparative Example 4, the technical solution of Example 4 using coal ash as a fluxing agent achieved a phosphate rock reduction rate of 81.5% at an acidity value of 0.8, which is 38.4% higher than that of the silica system.

[0111] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for producing yellow phosphorus by reducing phosphate rock, characterized in that, The method includes: in a non-oxidizing atmosphere, a mixture containing phosphate rock, a reducing agent and a fluxing agent is subjected to a reduction reaction, and the resulting yellow phosphorus furnace gas is washed and cooled with water so that the phosphorus vapor in the yellow phosphorus furnace gas is stored in water in liquid or solid form to obtain yellow phosphorus; The flux is selected from coal ash and optionally silica; The temperature of the reduction reaction is not lower than 1300℃; The reducing agent is selected from at least one of coke, white coal and lignite; The coal ash contains 35-50 wt% SiO2, 10-35 wt% Al2O3, 5-20 wt% Fe2O3, 0.5-10 wt% MgO, 3-15 wt% CaO, and 10-25 wt% C.

2. The method of claim 1, wherein, The method includes the following steps: (1) The phosphate rock, reducing agent and flux are dried separately and then mixed to obtain the mixture with a water content ≤0.2wt%; (2) In a non-oxidizing atmosphere, the mixture is subjected to the reduction reaction, and the resulting yellow phosphorus furnace gas is subjected to water washing and cooling to obtain the yellow phosphorus.

3. The method of claim 1 or 2, wherein, The molar ratio of C content in the reducing agent to P2O5 content in the phosphate rock is ≥5:

1.

4. The method of claim 3, wherein, The molar ratio of C content in the reducing agent to P2O5 content in the phosphate rock is 5.5-7:

1.

5. The method of claim 1 or 2, wherein, The amounts of the phosphate rock, coal ash, and optional silica are such that the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.6-0.

95.

6. The method of claim 5, wherein, The amounts of the phosphate rock, coal ash, and optional silica are such that the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.7-0.

9.

7. The method of claim 6, wherein, The amounts of the phosphate rock, coal ash, and optional silica are such that the mass ratio of (SiO2+Al2O3) to (CaO+MgO) is 0.75-0.

85.

8. The method of claim 1 or 2, wherein, The phosphate rock contains 20-30 wt% P2O5, 30-40 wt% CaO, 1-10 wt% MgO, 4-25 wt% SiO2, and 1-5 wt% Al2O3.

9. The method of claim 1 or 2, wherein, The reducing agent is coke.

10. The method of claim 1 or 2, wherein, The silica contains 85-98 wt% SiO2, 0.1-0.5 wt% Al2O3, 0.1-1 wt% Fe2O3, and 0.1-0.5 wt% CaO.

11. The method of claim 1 or 2, wherein, The conditions for the reduction reaction include: a temperature of 1300-1700℃ and a time of 10-200 min.

12. The method of claim 11, wherein, The conditions for the reduction reaction include: a temperature of 1400-1700℃ and a time of 20-100 min.

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