Method for efficient phosphorus removal in gas-based smelting reduction

Abstract

The application discloses a gas-based efficient phosphorus smelting reduction method, which comprises the following steps: obtaining liquid high-phosphorus slag through oxidation smelting; adding a reducing agent into the liquid high-phosphorus slag to obtain phosphorus-containing flue gas; and obtaining yellow phosphorus and yellow phosphorus tail gas through condensation of the phosphorus-containing flue gas. 3 / h~80Nm 3 / h. The application utilizes CO in the yellow phosphorus tail gas to stir the high-phosphorus slag melt, promotes efficient reduction reaction of the molten slag, reduces the limitation of the reduction reaction due to diffusion, shortens the reduction reaction time, improves the phosphorus smelting bed energy rate of the electric furnace volatilization, and reduces equipment investment.

Description

Technical Field

[0001] This invention relates to the field of phosphate rock smelting, and more specifically to a gas-based molten reduction method for efficient phosphate refining. Background Technology

[0002] Traditional electric furnace methods for producing phosphoric acid from yellow phosphorus produce high-quality phosphoric acid, capable of producing various fine phosphates downstream. However, the electric furnace process consumes a large amount of electricity, generates CO waste gas which is difficult to utilize, resulting in significant pollution and the production of large quantities of phosphorus sludge that are difficult to dispose of. Furthermore, the phosphoric acid production and yellow phosphorus production units are separate, and the heat released from the combustion and oxidation reaction of yellow phosphorus must be removed by cooling water or condensing acid, resulting in inefficient utilization and waste. All the heat required for yellow phosphorus production is provided by electricity, with electricity consumption ranging from 14,000 to 16,000 kWh per ton of yellow phosphorus.

[0003] To address the problems of high energy consumption, long process, high cost, poor acidity, and low conversion rate of phosphate rock in the electric furnace smelting of yellow phosphorus, and to reduce the load on materials requiring drying and granulation, a technical solution for preparing yellow phosphorus by oxygen-enriched side-blown oxidation smelting of phosphate rock combined with molten reduction is proposed.

[0004] However, in the currently disclosed schemes of oxygen-enriched side-blown oxidation smelting + molten reduction of phosphate rock, the reduction reaction time is long, the energy efficiency of the volatile phosphate refining bed is low, and the thermal utilization efficiency is low. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing methods, such as long reduction reaction time, low energy efficiency of volatile phosphorus refining bed, and low heat utilization efficiency, and to provide a gas-based molten reduction high-efficiency phosphorus refining method to solve the above problems.

[0006] A gas-based molten reduction method for efficient phosphorus refining includes: obtaining liquid high-phosphorus slag through oxidative smelting; adding a reducing agent to the liquid high-phosphorus slag for reduction to obtain phosphorus-containing flue gas; and condensing the phosphorus-containing flue gas to obtain yellow phosphorus and yellow phosphorus tail gas, respectively. While adding a reducing agent to the liquid high-phosphorus slag, yellow phosphorus tail gas is introduced into the liquid high-phosphorus slag through a fuel injection gun. The amount of yellow phosphorus tail gas introduced per ton of liquid high-phosphorus slag is 20 Nm³. 3 / h~80Nm 3 / h.

[0007] In the liquid high-phosphorus slag, the amount of reducing agent added can be more than 1 times the theoretical amount. Preferably, the amount of reducing agent added in the liquid high-phosphorus slag is 1 to 1.2 times the theoretical amount.

[0008] The process of obtaining the liquid high-phosphorus slag is as follows: phosphate rock and slag-forming flux are mixed to obtain a mixture with an acidity coefficient of 0.5 to 0.85, and the mixture is oxidized and smelted to obtain molten liquid high-phosphorus slag. When the mixture is oxidized and smelted, the process also includes introducing yellow phosphorus tail gas into the mixture through a fuel injector; the CO calorific value of the yellow phosphorus tail gas is used to melt the material, further reducing smelting energy consumption.

[0009] In the oxidation smelting step, low-boiling-point volatile elements (sulfur, arsenic, fluorine, chlorine, iodine, sodium, etc.) and moisture are volatilized into the flue gas and dust, which removes unnecessary gaseous impurities for subsequent gas-based melting and volatilization of yellow phosphorus in the gas-based melting and reduction furnace, thus achieving the purpose of gas-phase impurity removal. The slag-forming flux in this invention is silica, quartz, etc.; the fuel used in the oxidation smelting is pulverized coal or natural gas, etc.

[0010] In this invention, the acidity coefficient is the mass ratio of SiO2 to CaO. If the acidity coefficient is too low, the slag melting point increases and the viscosity becomes higher, affecting the fluidity of the metallurgical slag and the reduction behavior of phosphorus during the reduction period. Furthermore, if the acidity coefficient is too high, the flux ratio becomes too large, reducing the phosphorus grade of the mixed phosphate rock and increasing the unit production cost of phosphorus. Therefore, in this invention, the acidity coefficient of the mixture obtained after mixing phosphate rock and slag-forming flux is set to 0.5~0.85.

[0011] Excessive moisture content will cause a large amount of heat to be carried away in the form of water vapor, resulting in high energy consumption in yellow phosphorus smelting. The moisture content of the mixture is below 12%; preferably, the moisture content of the mixture is 2%-5%.

[0012] Furthermore, if the particle size is too large, the time required for the material to completely melt is longer. In this invention, the particle size of the mixture is ≤50mm.

[0013] The liquid high-phosphorus slag is obtained in an oxidation smelting furnace, and the addition of the reducing agent and the acquisition of yellow phosphorus are carried out in a reduction furnace.

[0014] The oxidation smelting furnace in this invention is a side-blown furnace, a top-blown furnace, a bottom-blown furnace, a top-side combined blowing furnace, and a top-bottom combined blowing furnace; wherein, phosphate rock powder, fuel, etc. can be selectively injected directly into the molten pool using a side-blown lance, which can improve the direct utilization rate of powdered phosphate rock; the liquid high-phosphorus slag in the oxidation smelting furnace is periodically discharged when the molten liquid level reaches the discharge height, and the liquid high-phosphorus slag is transferred into the reduction furnace via a chute or ladle; the reduction furnace is a closed side-blown reduction furnace.

[0015] The reducing furnace utilizes a side-blowing spray gun to inject a reducing agent and yellow phosphorus tail gas into the liquid high-phosphorus slag. The phosphorus-containing flue gas is then condensed in a water scrubbing tower to obtain yellow phosphorus and yellow phosphorus tail gas respectively.

[0016] In the oxidation smelting and reduction steps of this invention, if the temperature is too low, the slag fluidity is reduced, affecting the subsequent reduction of phosphorus and hindering slag discharge, making the process difficult to operate smoothly; if the temperature is too high, the unit energy consumption of smelting is increased, production costs are increased, and the service life of the refractory materials of the oxidation furnace is affected. The temperature of the oxidation smelting and reduction is 1350℃-1500℃. Preferably, the temperature of the oxidation smelting and reduction is 1400℃-1450℃.

[0017] As a preferred embodiment, the reducing agent is pulverized coal. The particle size of the pulverized coal is 0.05~0.3mm, which ensures that the reducing agent participates in the reduction reaction to the greatest extent possible.

[0018] The technical solution of this invention has the following advantages: 1. The present invention provides a gas-based molten reduction method for high-efficiency phosphorus refining. It utilizes CO injection from yellow phosphorus tail gas to agitate the high-phosphorus slag melt, promoting the efficient reduction reaction of the molten slag, reducing the limitation of the reduction reaction on diffusion, and shortening the reduction reaction time. The reduction reaction time can be shortened to (1 / 3-1 / 2)t, where t is the reduction time before yellow phosphorus tail gas is introduced. Therefore, it can effectively improve the efficiency of the electric furnace volatilization phosphorus refining bed and reduce equipment investment.

[0019] 2. The method provided by the present invention can also introduce yellow phosphorus tail gas into the melting furnace through a fuel injection gun, and use the CO calorific value of yellow phosphorus tail gas to melt materials, thereby reducing smelting energy consumption.

[0020] 3. The method of this invention is applicable to medium and low grade phosphate rock, broadening the exploitable resources of phosphate rock, improving the efficiency of yellow phosphorus extraction from phosphate rock, and increasing heat utilization. Compared with wet phosphorus extraction processes, it can solve the problem of phosphogypsum emissions at the source. In the side-blown smelting stage, volatile elements and moisture are removed to achieve the purpose of impurity removal, thus purifying the flue gas from the reduction and volatilization of yellow phosphorus and improving the quality of phosphorus-containing flue gas. Yellow phosphorus tail gas is used as a reducing agent and heat source in the reduction furnace, effectively improving the comprehensive utilization rate of yellow phosphorus tail gas. It consumes less electricity, has a high phosphorus recovery rate, low production cost per ton of phosphorus, low equipment investment, and low waste emissions, ultimately forming a green, low-carbon, and efficient yellow phosphorus smelting process technology. The efficiency of the molten reduction reaction is increased and the reaction time is shortened by agitating the melt in a closed reduction furnace; CO tail gas from yellow phosphorus is injected into the molten pool using a spray gun to increase the agitation of the melt, promote the reduction and volatilization of yellow phosphorus, and achieve the purpose of comprehensive utilization of yellow phosphorus tail gas; the efficiency of the reduction reaction is improved by injecting pulverized coal into the melt; and the latent heat of the yellow phosphorus reduction reaction can be provided by electrodes.

[0021] 4. The method of this invention can directly use powdered ore into the furnace, with no special requirements for lumps or powders, reducing the granulation process; using fuel as a heat source reduces electricity consumption and improves thermal efficiency; it has good applicability to raw ore moisture content, with ore below 12% suitable for furnace feeding, reducing the load on drying and granulation processes, or using waste heat from the melting furnace flue gas for raw material drying, avoiding investment in a separate drying system; the melting furnace adopts an oxidative smelting and oxygen-fueled combustion method, with low CO content in the tail gas of oxidative smelting and high combustion heat utilization efficiency; the reduction step in this invention only completes the melting and volatilization of liquid high-phosphorus slag and maintains the smelting temperature, effectively reducing electricity consumption and improving thermal efficiency; the introduction of yellow phosphorus tail gas in the melting reduction step improves reaction efficiency due to the agitation caused by the yellow phosphorus tail gas, further shortening the reduction time; and the main components of the flue gas in the furnace are CO and P4, with pure yellow phosphorus tail gas and low impurity content. After being collected by the yellow phosphorus tail gas washing tower system, yellow phosphorus product is obtained, which has high purity.

[0022] 5. Because no ore is fed into the reduction furnace of this invention, the dust rate is low; the phosphorus recovery rate is high, the purity is high, and the mud phosphorus production is low. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a process flow diagram of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the state during the system smelting process for producing yellow phosphorus in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the state during the system smelting process for producing yellow phosphorus in Embodiment 2 of the present invention.

[0025] Figure label: 11-Melting zone; 12-Spray gun; 13-First feed port; 14-First flue outlet; 15-Reduction zone; 16-Mouth of the gun; 17-Electrode; 18-Second feed port; 19-Second flue outlet; 110-Chutter; 21-Melting zone; 22-Secondary combustion tuyer; 23-Flue; 24-Feeding port; 25-Immersed fuel lance; 26-Melted liquid surface; 27-Melting zone furnace bottom; 28-Reduction zone baffle; 29-Transition zone from melting zone to reduction zone; 210-Reduction electrode; 211-Phosphorus iron discharge port; 212-Liquid slag discharge port; 213-Melting zone baffle. Detailed Implementation The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0026] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0027] Example 1 A gas-based molten reduction method for high-efficiency phosphorus refining employs an oxygen-enriched side-blown furnace and a side-blown reduction furnace. The oxygen-enriched side-blown furnace includes a cavity, a melting zone 11 located at the lower end of the cavity, a spray gun 12 located in the melting zone 11, a first feed port 13 and a first flue port 14 located above the melting zone 11. The side-blown reduction furnace includes a cavity, a reduction zone 15 located at the lower end of the cavity, a spray gun 16 located in the reduction zone 15, an electrode 17 extending into the reduction zone 15, a second feed port 18 and a second flue port 19 located above the reduction zone 15. The oxygen-enriched side-blown furnace and the side-blown reduction furnace are connected via a chute 110, specifically, one end of the chute 110 is connected to the melting zone 11, and the other end of the chute 110 is connected to the reduction zone 15, as shown below. Figure 2 As shown.

[0028] The method of gas-based molten reduction for high-efficiency phosphorus refining using the above-mentioned oxygen-enriched side-blown furnace and side-blown reduction furnace is as follows: Figure 1 As shown, it specifically includes: (1) Obtaining liquid high-phosphorus slag After mixing phosphate rock and slag-forming flux, a mixture with an acidity coefficient of SiO2 / CaO of 0.8 is obtained. In this embodiment, the phosphate rock used is medium- and low-grade phosphate rock, and the composition of the phosphate rock is shown in Table 1 below. Table 1. Phosphate rock composition (wt%)

[0029] Specifically, slag-forming flux quartz is added to the aforementioned phosphate rock, controlling the SiO2 / CaO mass ratio to be 0.8. The mixture is then crushed to obtain a particle size ≤50mm with a moisture content of 2.5%. This mixture is fed into the melting furnace through the charging port of an oxygen-enriched side-blown furnace. Pulverized coal is used as fuel in the melting furnace, injected into the melt using a fuel lance. The lance back pressure is 0.2~0.35 MPa, the oxygen excess coefficient is 1.2, the melt temperature is 1400℃, and the oxygen concentration is 75%. The oxygen excess coefficient in oxidative smelting refers to the ratio of the actual air supplied during fuel combustion to the theoretical air supply. Furthermore, 85% of the total yellow phosphorus tail gas produced by the system is returned to the melting furnace for combustion to supplement heat and reduce carbon consumption. The total amount of yellow phosphorus tail gas injected into the side-blown furnace is 3315.97 Nm³. 3 (The total amount of yellow phosphorus tail gas corresponding to 1.65t of yellow phosphorus is equivalent to 3315.97 Nm³ of mineral gas.) 3 / 12.88t =257.43 Nm 3 ).

[0030] The smelting products of the oxygen-enriched side-blown furnace include liquid high-phosphorus slag, molten dust, and molten flue gas. The molten dust and molten flue gas are obtained by filtering the furnace gas obtained from the oxidation and melting process in the oxygen-enriched side-blown furnace.

[0031] After pulverized coal is injected into the molten metal, the phosphorus content (P2O5) in the side-blown slag (liquid high-phosphorus slag) is 24.67%. The molten flue gas is mainly composed of CO2 due to complete combustion, with a CO2 volume fraction of 69.06%. Through side-blown enhanced oxidation combustion, the defluorination rate of the liquid high-phosphorus slag can reach 99%, specifically, the SiF4 volume fraction in the molten flue gas reaches 1.34%.

[0032] The inputs during the side-blowing stage are as follows: coal consumption of 0.09t per ton of ore, and yellow phosphorus tail gas injection of 257.37 Nm³ per ton of ore. 3 Oxygen consumption per ton of ore is 240 Nm³ 3 Compressed air consumption per ton of ore is 108 Nm³. 3 The quartz consumption per ton of ore was 0.32 tons; the output consisted of liquid high-phosphorus slag with a slag ratio of 80.51%, 180.46 kg of side-blown melting dust per ton of phosphorus (dust rate of 1.60%), and 558.19 Nm³ of flue gas per ton of ore. 3 .

[0033] (2) Restoration The liquid high-phosphorus slag from the side-blown furnace is transferred into a closed side-blown reduction furnace. The furnace's electric heating maintains the melt temperature at 1400℃. Pulverized coal, the reducing agent, is added through a side-blown nozzle at 1.2 times the theoretical amount. Simultaneously, yellow phosphorus tail gas is injected at a rate of 45 Nm³ per ton of liquid high-phosphorus slag. 3 / h (i.e., 45 Nm³ / h per ton of liquid high-phosphorus slag) 3 A certain amount of yellow phosphorus tail gas is injected into the furnace, which is produced by the system itself. By vigorously agitating the melt, phosphorus is efficiently volatilized into the furnace and flue. The furnace is an oxygen-free environment, and the flue gas mainly consists of CO and P4. This ensures that P4 is not oxidized into P2O5, and that O2 is completely burned into CO2, providing maximum calorific value for the melt's heat storage.

[0034] The products of the reduction and volatilization phosphorus refining stage in the electric furnace include dephosphorized slag, phosphorus-containing flue gas, ferrophosphorus, and volatile matter. The dephosphorized slag contains only 0.46% P2O5; the phosphorus-containing flue gas is mainly CO, with a CO volume fraction of 85.35% and a phosphorus P4 volume fraction of 7.10%; the ferrophosphorus contains 77.14% iron and 18% phosphorus; and the volatile matter contains 24.09% P2O5 and 1.63% Fe2O3.

[0035] In the stage of phosphorus refining through reduction and volatilization in a closed side-blown reduction furnace, the power consumption per ton of phosphorus is 3977 kW·h, the pulverized coal consumption is 1.89 t, and the phosphorus-containing flue gas volume per ton of phosphorus is 2373 Nm³. 3 One ton of phosphorus produces 0.13 tons of ferrophosphate and 180 kg of volatile dust per ton of phosphorus.

[0036] (3) Acquisition of yellow phosphorus The main components of the phosphorus-containing flue gas, by volume fraction, were P4: 7.10% and CO: 85.34%. After phosphorus collection in a water scrubbing tower, yellow phosphorus and yellow phosphorus tail gas were obtained. The yellow phosphorus tail gas contained CO with a volume fraction of 91.85%, HF 0.005%, and P4 0.022%. The estimated calorific value based on the flue gas composition was approximately 11500 KJ / Nm³. 3 The yield of yellow phosphorus after conversion is 96%.

[0037] Example 2 A gas-based molten reduction method for high-efficiency phosphorus refining, such as Figure 3 As shown, the process is carried out in a synthesis furnace, which includes a furnace body, a melting zone partition 213, a reduction zone partition 28, a ore feed port 24, a fuel spray gun 25, a reduction electrode 210, a yellow phosphorus flue gas outlet, a phosphorus iron discharge port 211, a liquid slag discharge port 212, a flue 23, and a secondary combustion air outlet 22.

[0038] The furnace body is sequentially configured into a melting zone 21, a transition zone 29, and a reduction zone by a melting zone partition 213 and a reduction zone partition 28 arranged in sequence. The melting zone partition 213 is located at the bottom of the furnace body between the melting zone 21 and the transition zone 29, and the reduction zone partition 28 is located between the transition zone and the reduction zone. It has a molten flow hole on it. The top of the molten flow hole is projected onto the vertical plane at a position lower than the top of the melting zone partition 213 is projected onto the vertical plane.

[0039] The ore feed port 24, fuel spray gun 25, flue 23, and secondary combustion air outlet 22 are all located in the melting zone. The ore feed port 24, flue 23, and secondary combustion air outlet 22 are located at the top of the melting zone. The fuel spray gun 25 is located at the bottom of the melting zone and below the projection of the top of the melting zone partition 213 on the vertical plane.

[0040] The reduction electrode 210, yellow phosphorus flue gas outlet, ferrophosphorus discharge outlet 211, and slag discharge outlet 212 are all located in the reduction zone. The yellow phosphorus flue gas outlet is located at the top of the furnace body in the reduction zone; the ferrophosphorus discharge outlet 211 and the slag discharge outlet 212 are located at the bottom of the furnace body in the reduction zone. Specifically, the ferrophosphorus discharge outlet 211 is located below the projection of the bottom of the molten flow hole onto the vertical plane, and the slag discharge outlet 212 is located above the projection of the top of the molten flow hole onto the vertical plane.

[0041] The process for processing phosphate rock in the synthesis furnace is as follows: Feed is introduced through the ore inlet, and the material is rapidly melted using a fuel spray gun to obtain liquid high-phosphorus slag. The liquid high-phosphorus slag flows into the reduction zone after passing through a transition zone. In the reduction zone, latent heat of reduction is provided by electrode heating. Simultaneously, pulverized coal or CO gas (from yellow phosphorus tail gas) is injected using a submerged spray gun to complete the molten reduction of the liquid high-phosphorus slag to prepare yellow phosphorus. Specifically, as follows: (1) Obtaining liquid high-phosphorus slag The mixture of phosphate rock and silica from Example 1 was used to obtain a mixture with a particle size ≤50mm and an acidity coefficient SiO2 / CaO of 0.5. The moisture content of the mixture was 5%. The mixture was added through the ore feed port of the synthesis furnace. Pulverized coal was used as fuel and injected into the melt through a fuel injector using a pulverized coal injection method. The back pressure of the injector was 0.2~0.35 MPa, the excess oxygen combustion coefficient was 1.2, the melt temperature was controlled at 1400℃, and the oxygen enrichment concentration was 75%.

[0042] After being mixed with pulverized coal, the phosphorus grade (P2O5) in the side-blown furnace slag (liquid high-phosphorus slag) is 28%.

[0043] (2) Restoration Liquid high-phosphorus slag is introduced into the reduction zone through a transition zone from the melting zone to the reduction zone. Electrodes are used to maintain the melt temperature at 1400℃. Pulverized coal, acting as a reducing agent, is added through a submerged fuel injector at a rate 1.2 times the theoretical amount. Simultaneously, 55 Nm³ / ton of phosphorus is injected through the submerged fuel injector. 3 The yellow phosphorus tail gas is produced per hour, and the pulverized coal particle size is 0.05~0.3mm.

[0044] The reduction and volatilization stage of phosphorus refining consumes 3958 kWh of electricity per ton of phosphorus, 1.78 tons of pulverized coal per ton of phosphorus, and 2369 Nm³ of phosphorus-containing flue gas per ton of phosphorus.3 One ton of phosphorus produces 0.13 tons of ferrophosphate and 160 kg of volatile dust; the reduction time per ton of phosphorus is basically the same as that per ton of phosphorus in Example 1.

[0045] (3) Acquisition of yellow phosphorus In this step, the main components of the phosphorus-containing flue gas by volume fraction were P4: 7.23% and CO: 85.33%. After phosphorus collection in a water scrubbing tower, yellow phosphorus and yellow phosphorus tail gas were obtained. The CO volume fraction in the yellow phosphorus tail gas reached 90.65%, and the estimated calorific value based on the flue gas composition was approximately 11500 KJ / Nm³. 3 The yield of yellow phosphorus was 98%.

[0046] Example 3 A gas-based molten reduction method for high-efficiency phosphorus refining differs from Example 1 in that the parameters of the reduction step are different, specifically including: The liquid high-phosphorus slag from the side-blown furnace is transferred into a closed side-blown reduction furnace. The furnace's electric heating maintains the melt temperature at 1350℃. Pulverized coal, acting as a reducing agent, is added through a side-blown nozzle at 1.1 times the theoretical amount. Simultaneously, 20 Nm³ of reducing agent is injected. 3 / h yellow phosphorus tail gas; other conditions are exactly the same as in Example 1.

[0047] In the stage of phosphorus refining through reduction and volatilization in a closed side-blown reduction furnace, the power consumption per ton of phosphorus is 3466 kW·h, the pulverized coal consumption is 1.68 t, and the phosphorus-containing flue gas volume per ton of phosphorus is 2350 Nm³. 3 One ton of phosphorus produces 0.13 tons of ferrophosphate and 160 kg of volatile dust; the reduction time per ton of phosphorus is basically the same as that per ton of phosphorus in Example 1.

[0048] The main components of the phosphorus-containing flue gas, by volume fraction, were P4: 7.10% and CO: 83.52%. After phosphorus collection in a water scrubbing tower, yellow phosphorus tail gas was obtained, with a CO volume fraction reaching 90.23%. Based on the flue gas composition, the estimated calorific value was approximately 11000 KJ / Nm³. 3 The yield of yellow phosphorus was 92%.

[0049] Example 4 A gas-based molten reduction method for high-efficiency phosphorus refining differs from Example 1 in that the parameters of the reduction step are different, specifically including: The liquid high-phosphorus slag from the side-blown furnace is transferred into a closed side-blown reduction furnace. The furnace's electric heating maintains the melt temperature at 1500℃. Pulverized coal, acting as a reducing agent, is added through a side-blown nozzle at 1.0 times the theoretical amount. Simultaneously, 80 Nm³ of reducing agent is injected. 3 / h yellow phosphorus tail gas.

[0050] In the stage of phosphorus refining through reduction and volatilization in a closed side-blown reduction furnace, the power consumption per ton of phosphorus is 3650 kW·h, the pulverized coal consumption is 1.45 t, and the phosphorus-containing flue gas volume per ton of phosphorus is 2680 Nm³. 3 The phosphorus produced 0.13t of ferrophosphorus per ton of phosphorus and 210kg of volatile dust per ton of phosphorus; the reduction time per ton of phosphorus was basically the same as that per ton of phosphorus in Example 1.

[0051] The main components of the phosphorus-containing flue gas, by volume fraction, are P4: 6.65% and CO: 80.20%. After phosphorus collection in a water scrubbing tower, yellow phosphorus tail gas is obtained, with a CO volume fraction reaching 89.50%. Based on the flue gas composition, the estimated calorific value is approximately 10200 KJ / Nm³. 3 The yield of yellow phosphorus was 96%.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is that in the reduction step, only pulverized coal as a reducing agent is added to the side-blown nozzle, without injecting yellow phosphorus tail gas. The amount of pulverized coal added is 1.2 times the theoretical amount. The method for efficient phosphorus refining using a gas-based molten reduction furnace and a side-blown reduction furnace includes the following steps: (1) Obtaining liquid high-phosphorus slag Phosphate ore and slag-forming flux were mixed to obtain a mixture with an acidity coefficient (SiO2 / CaO) of 0.8. Specifically, quartz slag-forming flux was added to the phosphate ore, controlling the SiO2 / CaO mass ratio to be 0.8, and the mixture was crushed to obtain a particle size ≤50mm. The moisture content of this mixture was 2.5%. The mixture was fed into a melting furnace through the feed port of an oxygen-enriched side-blown furnace. Pulverized coal was used as fuel in the melting furnace, injected into the melt using a fuel lance. The lance back pressure was 0.2~0.35 MPa, the oxygen excess coefficient was 1.2, the melt temperature was 1400℃, and the oxygen concentration was 75%. The total amount of yellow phosphorus tail gas returned from the oxygen-enriched side-blown furnace was 3315.97 Nm³. 3 (The total amount of yellow phosphorus tail gas corresponding to 1.65t of yellow phosphorus is equivalent to 3315.97 Nm³ of mineral gas.) 3 / 12.88t =257.43 Nm 3 ).

[0053] The smelting products of the oxygen-enriched side-blown furnace include liquid high-phosphorus slag, molten dust, and molten flue gas. The molten dust and molten flue gas are obtained by filtering the furnace gas obtained from the oxidation and melting process in the oxygen-enriched side-blown furnace.

[0054] The input and output of the side blowing stage are basically the same as in Example 1.

[0055] (2) Restoration The liquid high-phosphorus slag from the side-blown furnace is transferred into a closed side-blown reduction furnace. The electric heating of the closed side-blown reduction furnace is used to maintain the melt temperature at 1400℃. Pulverized coal, a reducing agent, is added through a side-blown spray gun. The amount of pulverized coal added is 1.2 times the theoretical amount. The addition of the reducing agent will efficiently volatilize phosphorus into the furnace and flue. The furnace is an oxygen-free environment. The flue gas components are mainly CO and P4, which can ensure that P4 is not oxidized to P2O5 and that O2 is completely burned by CO to CO2.

[0056] The products of the reduction and volatilization phosphorus refining stage in the electric furnace include dephosphorized slag, phosphorus-containing flue gas, ferrophosphorus, and volatile dust. In the closed-loop side-blown reduction furnace stage of phosphorus refining by reduction and volatilization, the power consumption is 4200 kW·h, the pulverized coal consumption is 2.80 t / ton of phosphorus, and the phosphorus-containing flue gas emission is 2023 Nm³ / ton of phosphorus. 3 One ton of phosphorus produces 0.14 tons of ferrophosphate and 180 kg of volatile dust; the reduction time of one ton of phosphorus is twice that of one ton of phosphorus in Example 1.

[0057] (3) Acquisition of yellow phosphorus Phosphorus-containing flue gas is treated with a water scrubbing tower to collect phosphorus, yielding yellow phosphorus and yellow phosphorus tail gas.

[0058] Comparative Example 2 The difference between this comparative example and Example 2 is that in the reduction step, only the reducing agent pulverized coal is added to the side-blowing nozzle, without injecting yellow phosphorus tail gas. The amount of pulverized coal added is 1.2 times the theoretical amount. The specific process is as follows: (1) Obtaining liquid high-phosphorus slag The mixture of phosphate rock and silica from Example 1 was used to obtain a mixture with a particle size ≤50mm and an acidity coefficient SiO2 / CaO of 0.5. The moisture content of the mixture was 5%. The mixture was added through the ore feed port of the synthesis furnace. Pulverized coal was used as fuel and injected into the melt through a fuel injector using a pulverized coal injection method. The back pressure of the injector was 0.2~0.35 MPa, the excess oxygen combustion coefficient was 1.2, the melt temperature was controlled at 1400℃, and the oxygen enrichment concentration was 75%.

[0059] (2) Restoration Liquid high-phosphorus slag is introduced into the reduction zone through the transition zone from the melting zone to the reduction zone. The melt temperature is maintained at 1400℃ using electrodes. Reducer pulverized coal is added by immersing the fuel spray gun. The amount of pulverized coal added is 1.2 times the theoretical amount, and the particle size of the pulverized coal is 0.05~0.3mm.

[0060] The reduction and volatilization stage of phosphorus refining consumes 4100 kWh of electricity per ton of phosphorus, 2.35 tons of pulverized coal per ton of phosphorus, and 2123 Nm³ of phosphorus-containing flue gas per ton of phosphorus. 3 One ton of phosphorus produces 0.14 tons of ferrophosphate and 180 kg of volatile dust; the reduction time of one ton of phosphorus is three times that of one ton of phosphorus in Example 2.

[0061] (3) Acquisition of yellow phosphorus In this step, the phosphorus-containing flue gas is treated by a water scrubbing tower to collect phosphorus, yielding yellow phosphorus and yellow phosphorus tail gas. The recovery rate of yellow phosphorus after phosphorus collection in the water scrubbing tower is 96%.

[0062] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A gas-based molten reduction method for high-efficiency phosphorus refining, comprising: Liquid high-phosphorus slag is obtained through oxidative smelting; a reducing agent is added to the liquid high-phosphorus slag for reduction to obtain phosphorus-containing flue gas; the phosphorus-containing flue gas is condensed to obtain yellow phosphorus and yellow phosphorus tail gas, respectively; characterized in that... While adding a reducing agent to the liquid high-phosphorus slag, yellow phosphorus tail gas is introduced into the liquid high-phosphorus slag through side blowing. The amount of yellow phosphorus tail gas introduced per ton of liquid high-phosphorus slag is 20 Nm³. 3 / h~80Nm 3 / h.

2. The method according to claim 1, characterized in that, In the liquid high-phosphorus slag, the amount of reducing agent added is 1 to 1.2 times the theoretical amount.

3. The method according to claim 1 or 2, characterized in that, The process of obtaining the liquid high-phosphorus slag is as follows: phosphate rock and slag-forming flux are mixed to obtain a mixture with an acidity coefficient of 0.5 to 0.85, and the mixture is oxidized and smelted to obtain molten liquid high-phosphorus slag. When the mixture is oxidized and smelted, the process also includes introducing yellow phosphorus tail gas into the mixture through a fuel injector.

4. The method according to claim 3, characterized in that, The moisture content of the mixture is below 12%; And / or, the particle size of the mixture is ≤50mm.

5. The method according to claim 4, characterized in that, The moisture content of the mixture is 2%-5%.

6. The method according to any one of claims 1-5, characterized in that, The liquid high-phosphorus slag is obtained in an oxidation smelting furnace, and the addition of the reducing agent and the acquisition of yellow phosphorus are carried out in a reduction furnace.

7. The method according to claim 6, characterized in that, In the oxidation smelting furnace, the liquid high-phosphorus slag is periodically discharged when the molten liquid level reaches the discharge height. The liquid high-phosphorus slag is then transferred into the reduction furnace via a chute or ladle. The reducing furnace is equipped with a side-blowing spray gun to inject reducing agent and yellow phosphorus tail gas into the liquid high-phosphorus slag.

8. The method according to any one of claims 1-7, characterized in that, The temperatures for the oxidation smelting and the reduction are 1350℃-1500℃.

9. The method according to claim 8, characterized in that, The oxidation smelting and reduction temperatures are 1400℃-1450℃.

10. The method according to any one of claims 1-9, characterized in that, The reducing agent is pulverized coal.

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