Preparation method of yellow phosphorus with low energy consumption

Abstract

The invention discloses a preparation method of yellow phosphorus with low energy consumption. The preparation method comprises the steps of acidolysis, mineralization, processing of a liquid-phase product II, preparation of high-grade low-impurity phosphorite, reduction of yellow phosphorus in an electric furnace and the like. According to the method, medium-low-grade complex collophanite which is difficult to effectively utilize in the prior art is used as a raw material, a large number of impurities enter acid-insoluble substances through chemical enrichment, metal ions entering acidolysis liquid are further complexed to be kept in a dissolved state, the phosphate concentrate is purified, and the phosphate concentrate is obtained. Explicated water, crystal water and intermolecular water in the phosphate concentrate are removed through burdening, balling, drying and calcining, the grade of phosphorite entering a furnace is greatly improved, the impurity content is effectively reduced, and the power consumption of yellow phosphorus is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of phosphorus chemical production technology, specifically to a method for preparing low-energy-consumption yellow phosphorus. Background Technology

[0002] Yellow phosphorus is an essential raw material for preparing various high-quality phosphorus-based products, such as pharmaceutical intermediates, semiconductors, new energy, aerospace and military materials, and is irreplaceable.

[0003] Early yellow phosphorus production primarily relied on blast furnace reduction using coke heating. Currently, the mainstream process for yellow phosphorus production is carbon reduction using electric furnace heating. The yellow phosphorus industry is energy-intensive; internationally, each ton of yellow phosphorus consumes 13,500-14,000 kWh of electricity. In my country, over 95% of phosphate rock is of medium to low grade, requiring even higher electricity consumption for yellow phosphorus production, typically between 13,500 and 15,000 kWh. When using medium to low grade complex collophane ore, the electricity consumption reaches 15,000-17,000 kWh. An effective way to reduce electricity consumption is to increase the grade and impurity content of the phosphate rock entering the yellow phosphorus electric furnace. Therefore, how to produce yellow phosphorus using medium to low grade complex collophane ore while maintaining low electricity consumption has become a key research focus in the industry.

[0004] Patent CN102718200B discloses a method for preparing industrial-grade phosphoric acid by decomposing low-grade phosphate rock with nitric acid. This patent uses nitric acid to decompose low-grade phosphate rock, followed by freeze crystallization of calcium nitrate, deep decalcification, and organic extraction to obtain industrial-grade phosphoric acid. Its purpose is to use nitric acid instead of sulfuric acid to obtain a low-cost industrial-grade phosphoric acid product.

[0005] Patent CN104909841B discloses a process for producing ammonium calcium magnesium phosphate and ammonium calcium magnesium nitrate from low-grade phosphate rock by nitric acid decomposition. This patent uses nitric acid to acid-decompose low-grade phosphate rock, aiming to maximize the utilization of calcium, magnesium, and phosphorus elements in the phosphate rock. It seeks to solve the problem of difficult tailings treatment after reverse flotation of low-grade phosphate rock, while simultaneously producing ammonium calcium magnesium phosphate and water-soluble ammonium calcium magnesium nitrate fertilizer, thus effectively utilizing the phosphorus, calcium, and magnesium in the low-grade phosphate rock.

[0006] Patent CN117303324B discloses a method for the decomposition and utilization of potassium phosphate ore. This patent includes the following steps: acid hydrolysis of potassium phosphate ore with nitric acid, controlling appropriate reaction conditions to ensure that the potassium leaching rate is ≤3% and the phosphorus leaching rate is ≥96%. The aim is to reduce the potassium leaching rate and achieve phosphorus and potassium separation by regulating the acid hydrolysis reaction conditions. Claims 7 and 8 also propose a mineralization reaction between the phosphorus-containing filtrate and lime slurry to obtain phosphate concentrate, but their purpose is to effectively separate phosphoric acid and calcium nitrate in the acid hydrolysis solution. The problem is that the mineralization reaction has a high pH (2.5~4.0), causing almost all impurities from the acid hydrolysis of potassium phosphate ore (such as Fe2O3, Al2O3, and CaO) to precipitate into the phosphate concentrate, leading to uncertainty regarding the subsequent utilization of the phosphate concentrate.

[0007] Patent CN111517832B discloses a method for separating P and Ca from low- and medium-grade phosphate rock and a method for producing fertilizer. This patent first uses nitric acid to decompose the low- and medium-grade phosphate rock, then mineralizes the filtrate to separate phosphorus and calcium. The mineralized solid is further acid-hydrolyzed with nitric acid, and the remaining process basically follows traditional methods to produce nitrate phosphate fertilizer. Traditional nitrate phosphate fertilizer requires phosphate concentrate with a grade greater than 30 wt%, making low- and medium-grade phosphate rock unsuitable for its production. This patent overcomes the difficulties in producing nitrate phosphate fertilizer and calcium ammonium nitrate water-soluble fertilizer from low- and medium-grade phosphate rock. In the second step of claim 1, the patent claims the requirement to "neutralize the acid-hydrolyzed solution, controlling the solution pH to 3.5 ≤ 6.5; then perform solid-liquid separation to obtain solid product I." However, its pH control is too high, causing almost all impurity ions in the acid-hydrolyzed solution (such as Fe2O3, Al2O3, and CaO) to precipitate into solid product I. If solid product I is used in the production of yellow phosphorus, the following unpredictable safety and yield problems will occur: First, when high-iron phosphate concentrate is used in the production of yellow phosphorus, a large amount of ferrophosphate is generated, reducing the phosphorus yield and the value of ferrophosphate, which is not conducive to subsequent utilization; Second, metal ions such as aluminum enter the slag, increasing power consumption; Third, the crystal water and intergranular water of solid product I will react with yellow phosphorus vapor during the production of yellow phosphorus to generate a large amount of highly toxic phosphine gas, posing a high safety risk.

[0008] Patent CN120738412A discloses a method for smelting yellow phosphorus and alloys using high-magnesium, low-grade phosphate rock. This patent involves batching and reducing high-magnesium, low-grade phosphate rock, calcareous flux, siliceous flux, iron ore, and carbonaceous reducing agent, aiming to smelt yellow phosphorus and alloys simultaneously. However, this method fails to improve the grade of the phosphate rock entering the yellow phosphorus electric furnace and does not save energy or reduce carbon emissions.

[0009] Patent CN111874882B discloses a process application method for low-grade phosphate rock in thermal phosphate chemical industry. This method utilizes a combined beneficiation-smelting-chemical process to comprehensively utilize low-grade phosphate rock with a P2O5 content of less than 20%, increasing the phosphate rock grade to above 25% through two enrichment processes: beneficiation and sintering. The key point of this patent lies in physical flotation, which moderately improves the phosphate rock grade without fundamentally altering energy consumption in the yellow phosphorus field.

[0010] Patents CN118387845A, CN111302318B, and CN121016596A are all methods for pelletizing yellow phosphorus ore, and their purpose is to reduce the pulverization rate of phosphate rock entering the yellow phosphorus electric furnace and reduce the generation of mud phosphorus.

[0011] In summary, regarding phosphate rock enrichment, the physical flotation technique for producing yellow phosphorus from low-grade phosphate rock is insufficient to significantly improve the grade of raw materials entering the furnace, and the power consumption per ton of yellow phosphorus remains high. The technique of enriching phosphate concentrate through acid hydrolysis of low-grade phosphate rock has flaws in its index control. Due to the large amount of impurities precipitating in the phosphate concentrate, the amount of byproduct ferrophosphorus increases during yellow phosphorus preparation, reducing the yellow phosphorus yield. Furthermore, the substance CaHPO4·2H2O in the phosphate concentrate undergoes the following side reactions during the reduction process:

[0012] 4CaHPO4·2H2O + 10C + 2SiO2 = 2*2CaO*SiO2 + P4(g) + 10CO(g) + 10H2O(g)

[0013] 4P4(g) + 15H2O(g) = 10PH3(g) + 3P2O5

[0014] The presence of water during the reduction process increases the pH3(g) content in the yellow phosphorus tail gas. This highly toxic pH3(g) poses a safety risk. Summary of the Invention

[0015] In view of the deficiencies in the literature, the purpose of this invention is to solve the shortcomings of the existing technology and the problem of high energy consumption, and to provide a method for preparing high-grade, low-impurity phosphate rock for yellow phosphorus.

[0016] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing low-energy-consumption yellow phosphorus, comprising the following steps:

[0017] S1. Acidolysis: This involves reacting low- to medium-grade complex collophane with calcium salt-soluble acids, primarily involving the following chemical reactions:

[0018] Ca5F(PO4)3 + 10H + =5Ca 2+ + 3H3PO4 + HF

[0019] CaCO3·MgCO3 +4H + =Ca 2+ +Mg 2+ +2CO2(g)+2H2O

[0020] 6H + +Fe₂O₃=2Fe 3+ +3H2O

[0021] 6H + +Al₂O₃=2Al 3+ +3H2O

[0022] After the reaction was completed, the product was filtered and washed to obtain solid product I, which was acid-insoluble, and liquid product I, which was crude phosphoric acid saturated with soluble calcium salt. The reaction conditions were: acid concentration of 10wt~70wt%, reaction temperature of 35~80℃, and reaction time of 0.25~2.0 hours.

[0023] S2, Mineralization: Prepare a slurry of complexing agent and mineralizing agent. Slowly and continuously add the slurry and liquid product I obtained in S1 to the reactor. React at 35-70℃ for 0.5-4.0 hours, controlling the final pH at 1.5-2.4. Filter and wash to obtain solid product II and liquid product II. Main reaction:

[0024] Fe 3+ (Al 3+ )+C - =Fe(Al)C n 3-n

[0025] H3PO4 + CaO + H2O = CaHPO4·2H2O

[0026] H3PO4+Ca 2+ +2OH - =CaHPO4·2H2O

[0027] 2H3PO4 + 3Ca 2+ +6OH - =Ca3(PO4)2 +6H2O

[0028] S3, Processing of liquid product II: The liquid product II obtained in S2 is adjusted and concentrated, the reaction temperature is controlled at 80~180℃, the pressure is 10.0~101.3kPa (A), the water content of the concentrate is 16.0~50.0, and the calcium soluble salt product is obtained by cooling, crystallization and filtration.

[0029] S4. Preparation of high-grade, low-impurity phosphate rock: Based on the composition of solid product II, solid product II obtained in S2 is mixed with an appropriate amount of silicon-based material, controlling the SiO2 / CaO weight ratio in the mixture to be 0.65~0.9. Pelletizing is then performed, with a pellet diameter of 5~35mm. Drying and calcining yields solid product III, with a compressive strength ≥1000N. The calcination temperature is controlled at 400~900℃, and the calcination time is 1~4 hours. Main reactions:

[0030] CaHPO4·2H2O = CaHPO4+2H2O (g)

[0031] 2CaHPO4 = Ca2P2O7 + H2O (g)

[0032] S5, Yellow Phosphorus Electric Furnace Reduction: The grade of solid product III (P2O5) is 25~45wt%; the temperature in the yellow phosphorus reduction zone is controlled at 1400~1450℃. Power consumption is 9000~12000 kWh per ton of yellow phosphorus. Main reactions:

[0033] 4Ca5F(PO4)3 + 30C + 11SiO2 = 10 (2CaO·SiO2) + 3P4(g) + 30CO(g) + SiF4(g)

[0034] 4Ca5F(PO4)3 + 30C + 9SiO2 = 9 (2CaO·SiO2) + 3P4(g) + 30CO(g) + 2CaF2

[0035] 2Ca2P2O7 + 10C + 2SiO2 = 2 (2CaO·SiO2) + P4(g) + 10CO(g)

[0036] 2Ca3(PO4)2 + 10C + 3SiO2 = 3 (2CaO·SiO2) + P4(g) + 10CO(g)

[0037] 4P4(g) + 15H2O(g) = 10PH3(g) + 3P2O5

[0038] P4(g) + 6H2O(g) + 6C = 4PH3(g) + 6CO(g)

[0039] Furthermore, the calcium-soluble acid is at least one of hydrochloric acid, nitric acid, and phosphoric acid.

[0040] Further, the complexing agent is at least one of fluoride salts, EDTA, acetylacetone, oxalic acid, sulfosalicylic acid, hydrocyanate, or a chelating agent that can provide a strong stability constant for the complex.

[0041] Furthermore, the mineralizing agent is at least one of the following substances: calcium carbonate, calcium oxide, high-silica phosphate rock, and gaseous ammonia.

[0042] Furthermore, the S3 adjustment and concentration refers to the need to adjust the composition of the liquid phase product when producing different calcium soluble salts. For example, when producing calcium ammonium nitrate, it is necessary to adjust the ammonium content in the solution.

[0043] Furthermore, the silicon-based material in S4 is at least one of silicon dioxide, high-silica phosphate rock, or other materials with a silicon dioxide content greater than 85 wt%.

[0044] Furthermore, in the acid hydrolysis of S1, the reaction conditions are: acid concentration of 20wt~50wt%, reaction temperature of 35~50℃, and reaction time of 0.3~1.0 hours.

[0045] Furthermore, the complexing agent in S2 is at least one of fluoride salts, EDTA, sulfosalicylic acid, and hydrocyanate.

[0046] Furthermore, in S2, the mineralization conditions are: a temperature of 40~50℃, a reaction time of 1.0~2.0 hours, and an endpoint pH controlled at 1.6~2.2.

[0047] Furthermore, in S4, the SiO2 / CaO weight ratio in the mixture is 0.75~0.85, the pellet diameter is 10~20mm, the compressive strength is ≥1000N, the calcination temperature is controlled at 700~900℃, and the calcination time is 1~2 hours.

[0048] Furthermore, in S5, the grade of solid product III (P2O5) is 30~45wt%; the power consumption per ton of yellow phosphorus is 9000~10000kw·h.

[0049] The beneficial effects of this invention are as follows:

[0050] This invention uses low- to medium-grade complex phosphate rock, which is difficult to utilize effectively with existing technologies, as raw material. Through chemical enrichment, a large number of impurities enter the acid-insoluble matter, and the metal ions that enter the acid hydrolysis solution undergo further complexation to maintain their dissolved state, thus purifying the phosphate concentrate. Through batching, pelletizing, drying, and calcination, visible water, crystal water, and intermolecular water in the phosphate concentrate are removed, resulting in a significant increase in the grade of the phosphate rock entering the furnace, an effective reduction in the impurity content, and a significant reduction in the power consumption of yellow phosphorus. Attached Figure Description

[0051] Figure 1 A flowchart illustrating the process for preparing low-power yellow phosphorus from medium- and low-grade complex collophane ore. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] Acid hydrolysis: Weigh 1000g of medium-low grade complex phosphate rock (components shown in Table 1), add 2100.0g of 40wt% dilute nitric acid, control the temperature at 40~45℃, and react for 1.0 hour. After the reaction, filter and wash. The solid product I is acid-insoluble, weighing 325.94g (dry basis), containing 1.41% P2O5 (index data shown in Table 5). The liquid product I (including washing liquid) weighs 3060.0g, containing 5.85% P2O5 and 9.35% CaO (index data shown in Table 6). The calculated phosphate rock decomposition rate is 97.44%.

[0055] Mineralization: Add liquid product I to the reaction tank (4000ml), start the stirring paddle in the reaction tank, and after the temperature of the reaction tank reaches the predetermined temperature (40℃), continuously add calcium carbonate. Control the reaction time to 120 minutes. When the pH reaches 1.8~2.0, filter. The filter cake is solid product II. The filter cake (dry basis) weighs 462.86g, containing 38.72% P2O5 and 29.40% CaO (see Table 7 for details). The liquid product II weighs 3091.80g (including wash water) (see Table 8 for details).

[0056] Processing of liquid product II: Place liquid product II in a concentration vessel, control the temperature to 85.0~90.0℃, control the vacuum degree to 10~15kPa(A), and when the specific gravity of the solution reaches 1.5~1.55, cool and granulate to obtain 1555.02kg of nitro fertilizer (composition data are shown in Table 9).

[0057] Preparation and reduction of high-grade, low-impurity phosphate rock: 94.22g of silica (composition data shown in Table 2) was weighed and uniformly mixed with solid product II. The SiO2 / CaO weight ratio was set at 0.8, and the pellet size was 10~15mm. The mixture was calcined at 800℃ for 1.5 hours. The resulting material was solid product III, weighing 439.50g. The compressive strength of solid product III was measured to be 1350N, and the content of P2O5 was 39.67wt%, CaO was 30.15wt%, and SiO2 was 22.58wt% (indicators shown in Table 10). The power consumption for preparing yellow phosphorus from this material was measured to be 9106.17kw·h / t P4.

[0058] The process flow diagram for preparing yellow phosphorus from low- to medium-grade complex collophane ore using high-grade, low-impurity phosphate rock is attached. Figure 1 As shown.

[0059] The composition of medium- and low-grade complex collophane in this embodiment is shown in Table 1:

[0060] Table 1 Composition of medium and low grade phosphate and potassium ores

[0061]

[0062] Table 2 Silica Composition

[0063]

[0064] Table 3 Composition of medium- and low-grade high-silica phosphate rock

[0065]

[0066] Examples 2 to 6

[0067] Examples 2-4 were prepared using the same methods as Example 1, with the following differences: Example 2 used the same low-grade complex phosphate rock as Example 1 (see Table 1), with a nitric acid concentration of 60% and an addition amount of 1420g during the acidolysis stage. Other conditions are shown in Table 4. During the mineralization stage, 30g of EDTA-2Na and 40g of sulfosalicylic acid were added. Examples 3-4 used low-grade high-silica phosphate rock (see Table 3). In Example 3, 2060g of 40% dilute nitric acid was added, and other conditions are shown in Table 4. In Example 4, 1380g of 60% dilute nitric acid was added, and the mineralizing agents used were high-silica phosphate rock (see Table 3) and calcium oxide. The addition amount of high-silica phosphate rock was 798.19g, and the pH was adjusted using calcium oxide. The experimental conditions for Examples 1-4 are shown in Table 4, and the experimental and analytical results are shown in Tables 5-11.

[0068] Table 4. Test conditions for Examples 2-4

[0069]

[0070] Tables 5 and 6 are the material data tables for the acidolysis stage of Examples 1 to 4.

[0071] Table 5 Solid product I data

[0072]

[0073] Table 6 Data on Liquid Phase Product I

[0074] Tables 7 and 8 are the material data tables for the mineralization stages of Examples 1 to 4.

[0075] Table 7 Data on Solid Product II

[0076]

[0077] Table 8 Data on Liquid Phase Product II

[0078]

[0079] Table 9 shows the solid fertilizer data processed from liquid phase product II of Examples 1-4.

[0080] Table 9 Data on Processed Products of Liquid Phase Product II

[0081]

[0082] Tables 10 and 11 are material data tables for the preparation and reduction stages of high-grade phosphate rock for yellow phosphorus in Examples 1-4.

[0083] Table 10 Composition data of solid product III

[0084]

[0085] Table 11 Data on the reduction of solid product III to prepare yellow phosphorus

[0086]

[0087] Example 5

[0088] Example 5 was prepared using the same method as Example 1. The difference was that hydrochloric acid was used instead of nitric acid for the calcium-soluble acid, the phosphate rock was medium-to-low grade high-silica phosphate rock (see Table 3 for details), and calcium carbonate and calcium oxide were used as the mineralizing agents. The reaction conditions are shown in Table 12.

[0089] Table 12 Test conditions for Example 5

[0090]

[0091] Acid hydrolysis stage data table

[0092] Table 13 Solid Product I Data

[0093]

[0094] Table 14 Data on Liquid Phase Product I

[0095] Mineralization Stage Data Table

[0096] Table 15 Data on Solid Product II

[0097]

[0098] Table 16 Data on Liquid Phase Product II

[0099]

[0100] Data sheet of solid fertilizer processed from liquid phase product II

[0101] Table 17 Data on Processed Products of Liquid Phase Product II

[0102]

[0103] Data on the preparation and reduction of yellow phosphorus from high-grade, low-impurity phosphate rock

[0104] Table 18 Composition data of solid product III

[0105]

[0106] Table 19 Data on the reduction of solid product III to prepare yellow phosphorus

[0107]

[0108] In summary, this invention uses medium- and low-grade complex collophane ore as raw material to achieve the preparation of high-grade phosphate rock for yellow phosphorus. The power consumption of yellow phosphorus is 60% to 69% of that of the traditional process (the power consumption of traditional yellow phosphorus is calculated as 15,000 kWh), which significantly reduces the production cost of yellow phosphorus and lays the foundation for the industrial application of medium- and low-grade complex collophane ore.

[0109] The specification and drawings of this invention are intended to be illustrative rather than restrictive. Based on this invention, those skilled in the art can make substitutions and modifications to some of the technical features without creative effort, and all such modifications are within the scope of protection of this invention.

Claims

1. A method for preparing low-energy-consumption yellow phosphorus, comprising: S1, acid hydrolysis: react medium- to low-grade complex collophane with calcium salt soluble acid. After the reaction is complete, filter and wash to obtain solid product I and liquid product I. S2, mineralization: Add complexing agent and mineralizing agent slurry to the reactor, then add liquid phase product I to react. After the reaction is completed, filter and wash to obtain solid phase product II and liquid phase product II. S3. Processing of liquid product II: Liquid product II is prepared and concentrated, and then cooled, crystallized, and filtered to obtain calcium soluble salt product. S4. Preparation of high-grade, low-impurity phosphate rock: Solid product II is mixed with an appropriate amount of silicon-based material, and the weight ratio of SiO2 / CaO in the mixture is controlled to be 0.65~0.

9. The mixture is pelletized, and the resulting spherical product is dried and calcined to obtain solid product III. S5, yellow phosphorus electric furnace reduction: the grade of solid product III is 25~45 wt%; The temperature in the yellow phosphorus reduction zone is controlled at 1400~1450℃, and the power consumption per ton of yellow phosphorus is 9000~12000kw·h.

2. The preparation method according to claim 1, wherein: The calcium salt soluble acid mentioned in step S1 is selected from at least one of hydrochloric acid, nitric acid, and phosphoric acid, with a mass concentration of 10-70%. The reaction temperature is 35~80℃, and the reaction time is 0.25~2.0 hours.

3. The preparation method according to claim 2, wherein: The mass concentration of the calcium salt soluble acid is 20-50%; The reaction temperature is 35~50℃, and the reaction time is 0.3~0.0 hours.

4. The preparation method according to claim 1, wherein: The complexing agent in step S2 is selected from at least one of the following: fluoride salts, EDTA, acetylacetone, oxalic acid, sulfosalicylic acid, hydrocyanate, or other chelating agents; The mineralizing agent is selected from at least one of the following: calcium carbonate, calcium oxide, high-silica phosphate rock, and gaseous ammonia. The reaction conditions are as follows: reaction temperature 35~70℃, reaction time 0.5~4.0 hours, and final pH controlled at 1.5~2.

4.

5. The preparation method according to claim 4, wherein: The complexing agent is selected from at least one of the following: fluoride salts, EDTA, sulfosalicylic acid and hydrocyanate; The reaction conditions are as follows: reaction temperature 40~50℃, reaction time 1.0~2.0 hours, and final pH controlled at 1.6~2.

2.

6. The preparation method according to claim 1, wherein: The conditions for the concentration reaction described in step S3 are: reaction temperature 80~180℃, reaction pressure 10.0~101.3kPa, and water content of the concentrate 16.0~50.0%.

7. The preparation method according to claim 1, wherein: The silicon-based material mentioned in step S4 is at least one of silicon dioxide, high-silica phosphate rock, or other materials with a silicon dioxide content greater than 85 wt%. The SiO2 / CaO weight ratio in the mixture is 0.75~0.85, and the diameter of the spherical products is 5~35mm; The drying and calcining temperature is 400~900℃, and the calcination time is 1~4 hours; The compressive strength of the solid product III is ≥1000N.

8. The preparation method according to claim 7, wherein: The diameter of the spherical product is 10-20 mm, the calcination temperature is controlled at 700-900℃, and the calcination time is 1-2 hours.

9. The preparation method according to claim 1, wherein: The grade of solid product III in step S5 is 30~45wt%; the temperature of the yellow phosphorus reduction zone is controlled at 1400~1450℃, and the power consumption per ton of yellow phosphorus is 9000~10000kw·h.

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