CN118619221A - A system and method for producing P2O5 by melting - Google Patents

Abstract

The invention discloses a system and method for producing _P2O5 by melting, wherein a method for producing _{P2O5 by} melting includes obtaining liquid high _- phosphorus slag, adding _a reducing agent to the liquid high-phosphorus slag for reduction to obtain phosphorus-containing flue gas, converting the phosphorus-containing _flue gas into _P2O5 smoke dust after combustion, and recovering _P2O5 products through _{the P2O5} smoke dust; the liquid high-phosphorus slag is obtained in an oxidation smelting furnace, and the addition of the reducing agent and the combustion conversion are both carried out in a reduction furnace; the liquid high-phosphorus slag is obtained by mixing phosphate ore and slag-making flux to obtain a mixed material with an acidity coefficient of 0.65 to 0.85, and the mixed material is oxidized and smelted to obtain molten liquid high-phosphorus slag. The invention improves the tolerance of phosphate ore sources and broadens the utilization boundary, improves the thermal utilization rate of fuel, and has the advantages of high quality of the prepared _P2O5 product _, low comprehensive production cost, and good technical and economic performance.

Description

A system and method for producing P2O5 by melting

Technical Field

The present invention relates to the field of phosphate _ore smelting, and in particular to a system and method for producing _P2O5 by melting.

Background Art

The wet phosphoric acid process produces a large amount of phosphogypsum waste residue. For every ton of phosphoric acid produced, 4.5 to 5 tons of phosphogypsum will be produced. The main component of phosphogypsum is calcium sulfate dihydrate, and it also contains undecomposed phosphate rock, residual phosphoric acid, fluoride, acid insoluble matter, organic matter and other components. The storage of phosphogypsum not only occupies land resources, but also seriously pollutes the environment. In particular, the harmful substances contained in it, such as water-soluble phosphorus pentoxide and water-soluble fluorine, directly threaten environmental safety.

At present, phosphoric acid production and yellow phosphorus production equipment are set up separately. The heat released by the combustion and oxidation reaction of yellow phosphorus must be removed by cooling water or condensed acid. This part of the heat is not well utilized and is wasted. In addition, the phosphoric acid produced by the traditional electric furnace method of yellow phosphorus acid production is of high quality and can produce various fine phosphates downstream. However, due to the defects of high power consumption, high impurity content in furnace gas, large pollution, difficult utilization of waste gas CO, and large amount of phosphorus mud produced by the electric furnace process; therefore, untreated furnace gas containing yellow phosphorus is conventionally used to prepare phosphoric acid products, but because the furnace gas contains many harmful elements and highly corrosive substances, the combustion gas has strong corrosiveness, which greatly damages the phosphoric acid production equipment. At the same time, all the heat required for the production of yellow phosphorus by the traditional electric furnace method is provided by electricity, and the power consumption per ton of yellow phosphorus is 14000~16000kWh, which is relatively high in energy consumption. Moreover, during the electric furnace smelting process, a portion of solid dust is always carried out, and the dust content in the furnace gas is 20~50 g/ ^Nm3 . If high-carbonate phosphate ore is encountered, the dust will be carried out more seriously due to decomposition and crushing at high temperature. The dust content in the furnace gas is as high as 100 g/ ^Nm3 or more, which greatly affects the yield and quality of yellow phosphorus, and further affects the conversion rate and acid quality of subsequent phosphoric acid production.

Moreover, in the traditional electric furnace yellow phosphorus method, excessive moisture content in the charge often deteriorates the operation, blocks the charge pipe, makes the charge unsmooth, and causes agglomeration and bridging in the electric furnace, causing the charge to collapse, resulting in flames and even explosion accidents; and a large amount of free water enters the furnace, the side reactions increase, the tail gas volume increases, and the content of impurities such as PH ₃ and H ₂ S in the yellow phosphorus tail gas also increases. Especially in the rainy season, when the moisture content of the raw materials increases, the H ₂ S content in the yellow phosphorus tail gas increases significantly, causing adverse effects on desulfurization. Due to the increase in side reactions, the consumption of raw material carbon and electrodes increases, the recovery rate of elemental phosphorus decreases, and the output of product phosphorus decreases.

Therefore, in order to obtain high-quality phosphoric acid, it is necessary to obtain high-quality yellow phosphorus first. In the preparation of high-quality yellow phosphorus, the materials entering the furnace need to be dried to a moisture content of less than 2 _% , and the powder ore needs to be granulated and balled before entering the furnace; that is, the phosphate ore needs to be dried, granulated and other pre-treatments before entering the electric furnace for reduction smelting; this method leads to higher requirements for furnace materials when producing high-quality _P2O5 , and additional drying equipment needs to be set up. At the same time, _{phosphorus-containing furnace gas contains a lot of impurities. If the P2O5 product} is prepared by direct combustion, there will be a problem of poor _acidity . It needs to be removed before the preparation of high-quality _P2O5 products can be effectively achieved, and the preparation process is complicated.

Summary of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art that the phosphoric acid production and yellow phosphorus production devices are separated, resulting in high requirements for furnace materials, high energy consumption, poor acid quality, and complex processing, thereby providing a system and method _for melting production of _P2O5 to solve the above problems.

A method for producing yellow phosphorus by smelting phosphate ore, comprising: obtaining liquid high-phosphorus slag, adding a reducing agent to the liquid high-phosphorus slag for reduction to obtain phosphorus-containing flue gas, converting the phosphorus-containing flue gas into _{P2O5 -} containing smoke dust through combustion, and recovering _{a P2O5 product through the P2O5 -} containing _smoke dust;

The liquid high-phosphorus slag is obtained in an oxidation smelting furnace, and the reducing agent is added and the combustion conversion is carried out in a reduction furnace;

The process of obtaining the liquid high-phosphorus slag is as follows: phosphate ore and slag-making flux are mixed to obtain a mixture with an acidity coefficient of 0.65-0.85, and the mixture is oxidatively smelted to obtain molten liquid high-phosphorus slag.

The acidity coefficient is the mass ratio of _SiO2 /CaO. If the acidity coefficient is too low, the slag melting point will increase and the viscosity will be large, which will affect the fluidity of the metallurgical slag and the reduction behavior of phosphorus in the reduction period. In addition, if the acidity coefficient is too high, the phosphorus grade of the mixed phosphate ore will be reduced due to the excessive flux ratio, and the unit production cost of phosphorus will be increased. Therefore, the acidity coefficient of the mixed material obtained by mixing the phosphate ore and the slag-making flux in the present invention is set to 0.65-0.85.

The phosphorus-containing flue gas is directly subjected to secondary combustion in the furnace of the reduction furnace and tertiary combustion in the flue of the reduction furnace to convert the yellow phosphorus in the phosphorus-containing flue gas into _{P2O5 -} containing smoke.

In the oxidation smelting and reduction steps of the present invention, if the temperature is too low, the fluidity of the slag is reduced, the subsequent phosphorus reduction is affected, and the discharge of the slag is not conducive, resulting in the difficulty of the process; if the temperature is too high, the unit energy consumption of smelting is increased, the production cost is increased, and the service life of the refractory material of the oxidation furnace is affected. Therefore, the temperature of the oxidation smelting in the present invention is preferably 1350°C-1500°C, preferably 1400°C-1450°C.

The traditional electric furnace process requires that the moisture content of the raw materials entering the furnace must be <2%. For raw materials with a moisture content higher than 2%, it is necessary to carry out the drying and granulation process of the raw materials, which limits the application of the raw materials. After the present invention optimizes the operating process, the moisture content of the raw materials is applicable to a wider range, and the raw materials with a moisture content of more than 2% can be directly put into the furnace, shortening the process flow and reducing production costs. However, if the moisture content is too high, a large amount of heat will be taken away in the form of water vapor, resulting in high energy consumption for yellow phosphorus smelting. The moisture content of the mixed material described in the present invention is less than 12%, preferably 2% to 5%.

The present invention has no particular restriction on the particle size of the raw materials fed into the furnace, as long as they can be added to the oxidation smelting furnace for oxidation smelting. However, if the particle size is too large, it will take a long time for the material to be completely melted. The particle size of the mixed material in the present invention is preferably ≤50mm.

The amount of the reducing agent added to the liquid high-phosphorus slag may be more than 1 times the theoretical amount, preferably 1 to 2 times.

The reducing agent includes at least one of anthracite, blue carbon, graphite powder and coke;

The slag-making flux is silica, quartz stone, etc.; the fuel is pulverized coal or natural gas, etc.

If the reducing agent particles are too large, the contact interface between the reaction medium is small and the reaction time is long; if the particles are too small, the dust rate is too high. In the present invention, the reducing agent preferably has a particle size of 15 to 35 mm, which can maximize the participation of the reducing agent in the reduction reaction.

A system for producing yellow phosphorus by smelting phosphate ore, comprising:

Oxidation smelting furnace, used for oxidative smelting of phosphate ore and slag-making flux into molten liquid high-phosphorus slag;

The reduction furnace comprises a liquid high-phosphorus slag input port, a reducing material input port and a flue gas outlet, and is used to reduce the liquid high-phosphorus slag to obtain phosphorus-containing flue gas;

The combustion devices are respectively arranged in the reduction furnaces and are used for burning yellow phosphorus to convert it into P ₂ O ₅ .

The combustion device is preferably arranged on the furnace and the flue of the reduction furnace.

The oxidation smelting furnace 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 sprayed directly into the molten pool using a loading side-blowing spray gun, which can improve the direct utilization rate of the powdered phosphate rock; when the liquid level of the high-phosphorus slag melt in the side-blown furnace reaches the discharge height, it is discharged periodically and the liquid high-phosphorus slag is transferred into a closed reduction furnace.

The reduction furnace is a side-blown reduction furnace.

The technical solution of the present invention has the following advantages:

1. A method for producing _P2O5 by melting provided by the present invention proposes to use an _oxidation smelting furnace to quickly oxidize and melt a phosphate rock mixture to prepare a molten liquid high-phosphorus slag, which can expand the applicable range of furnace materials without requiring the particle size and water content of the furnace materials, and is not affected by the reuse of phosphorus mud; at the same time, by controlling the acidity coefficient of the mixed material composed of phosphate ore and slag-making flux to be 0.65-0.85, the loss of phosphorus element caused by the volatilization of phosphorus element in the process of preparing the molten liquid high-phosphorus slag can be reduced; and in this step, harmful elements and moisture can be effectively removed, avoiding the problem of low quality and high impurities of phosphorus-containing flue gas when the molten liquid high-phosphorus slag enters a reduction furnace for reduction volatilization and phosphorus refining to volatilize phosphorus into the flue gas to obtain phosphorus-containing flue gas, and finally, the high-quality phosphorus-containing flue gas is directly burned in the reduction furnace without impurity removal to convert the yellow phosphorus in the phosphorus-containing _flue gas into _P2O5 dust, and high-quality _P2O5 can be recovered through the _P2O5 dust _{. 5} products, effectively achieving the goal of efficient, energy-saving and environmentally friendly extraction of phosphorus resources.

Among them, the phosphate ore is directly subjected to oxidation smelting treatment first. Because the melting process is controlled as oxidation smelting under a specific acidity coefficient, the oxygen potential in the furnace is relatively high, and the phosphorus element in the phosphate ore is not easy to volatilize and enter the slag to form high-phosphorus slag, thereby avoiding the loss of phosphorus element; the oxidation smelting furnace is a molten pool smelting, and there is no raw material layer, so the material state and moisture content of the phosphate ore are not required to be high, and the application range is wider; at the same time, in the melting process of the oxidation smelting furnace, the harmful elements such as sulfur, arsenic, fluorine, and chlorine (S, As, F, Cl) in the phosphate ore can be removed by oxidation smelting, and the water ( _H2O ) brought by the materials entering the furnace can be removed, thereby improving the quality of the phosphorus-containing flue gas volatilized by the reduction furnace, and then improving the quality of the _{P2O5 -} containing smoke after combustion, reducing the steps of impurity removal treatment of the _{P2O5 -} containing _smoke to obtain high-quality _P2O5 , and simplifying the preparation process; the present invention has the advantages of reducing the corrosiveness of the _smoke containing _P2O5 , reducing the emission of the _{smoke containing P2O5 ,} saving production energy consumption, etc.

Specifically, the oxidation smelting furnace mainly completes the melting of the charge, and the phosphorus element is still retained in the slag to form liquid high-phosphorus slag. During the melting process, harmful elements (S, As, F, Cl, I, Na, etc.) and the water ( _H2O ) contained in the material entering the reduction furnace can be effectively removed, providing a removal effect for the subsequent reduction furnace to carry out reduction volatilization phosphorus refining, and improving the purity of the phosphorus-containing flue gas in the reduction furnace, thereby reducing the smoke dust rate, reducing the output of mud phosphorus in the phosphorus collection process, improving the phosphorus recovery rate and reducing energy consumption; among them, the CO content in the furnace gas of the reduction furnace is relatively high. When a spray gun is used in the furnace and flue for oxygen supplementation, secondary combustion and tertiary combustion, the CO combustion calorific value can be fully utilized to reduce energy consumption; the phosphorus-containing flue gas has a high phosphorus concentration and a low _{impurity content, so that the P2O5 product} converted by combustion has a high purity, reducing the load of the subsequent phosphoric acid preparation and purification process, and obtaining _a high-quality _P2O5 product. At the same time, because moisture can be removed during the melting process of the oxidation smelting furnace, the oxidation smelting furnace has a wide range of applicability to the moisture content and particle size (powder ore, lump ore, and pellets) of the charge entering the furnace; charges with a moisture content of less than 12% can be fed into the furnace, which can reduce the material drying process and avoid the investment in a separate drying system; powder ore can be directly used to enter the furnace, and there are no special requirements for lump and powder materials, which can reduce the granulation process; or the waste heat of the melting furnace flue gas can be used to dry the raw materials to save energy. Meanwhile, the oxidation melting bed efficiency of the oxidation smelting furnace adopted by the present invention is 27-50 t/(d·m ² ), which is much higher than the bed efficiency of 5-12 t/(d·m ² ) of the electric furnace commonly used in the current yellow phosphorus production. The fuel can be anthracite, natural gas, kerosene, etc. The oxidation smelting furnace adopts oxidation smelting, the tail gas CO content is low, and the combustion heat utilization efficiency is high; meanwhile, the reduction furnace only completes the reduction volatilization of liquid high-phosphorus slag and the heat preservation effect of maintaining the smelting temperature, effectively reducing the influence of the diffusion rate of solute atoms on the phosphorus reduction chemical reaction rate, thereby improving the phosphorus reduction volatilization reaction kinetics, shortening the reaction time, and improving the processing capacity and efficiency of the electric furnace; compared with the traditional electric furnace for yellow phosphorus refining, the smoke rate is lower, the melting reduction reaction efficiency is high, the reduction reaction time of the reduction furnace is shortened, the bed efficiency of the reduction furnace for volatilization phosphorus refining is improved, and the preparation of high-quality P ₂ O ₅ products can be effectively realized by directly using phosphorus-containing flue gas for combustion, without the need for additional impurity removal treatment, reducing equipment investment, greatly reducing power consumption, and saving costs.

In summary, the present invention improves the tolerance of phosphate rock sources and broadens _{the utilization boundaries, achieves the purpose of producing P2O5 products by low-energy smelting, improves the thermal utilization rate of fuel, and has the advantages of high quality of the prepared P2O5 products , low} comprehensive production cost, and good technical and economic performance.

2. Under the same production capacity conditions, the present invention greatly reduces equipment investment and floor space, improves the on-site operating environment and reduces labor intensity; at the same time, since electrodes are no longer used as heat sources, problems such as difficult electrode operation, easy electrode breakage, and bridging and collapse of electric furnace charges can be effectively avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a process flow chart of Example 1 of the present invention;

FIG. 2 is a schematic diagram of the state of the system in Example 1 of the present invention during the process of melting and producing P ₂ O ₅ .

DETAILED DESCRIPTION

The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be purchased commercially.

Example 1

A method for producing _{P2O5 by} melting, as shown in FIG1 and FIG2, comprises:

(1) Obtaining liquid high-phosphorus slag

The phosphate ore and the slag-forming flux are mixed to obtain a mixed material with an acidity coefficient of 0.8. The phosphate ore used in this embodiment is a medium- and low-grade phosphate ore, wherein the composition of the phosphate ore is shown in Table 1 below;

Table 1 Phosphate ore composition (wt%)

_{P2O5 ​} I- F- MgO CO2 Fe2O3 Al2O3 Cl- CaO SiO2 TiO2 31.67 0.0046 2.67 0.79 2.1 1.71 2.22 0.039 47.29 7.04 0.017

Specifically, quartz stone, a slag-making flux, is added to the above-mentioned phosphate ore, the mass ratio of the acidity coefficient SiO ₂ /CaO is controlled to be 0.8, and the mixture is crushed to obtain a particle size of ≤50 mm, the moisture content of the mixture is 2.5%, and the mixture is added through the charging port of the oxygen-enriched side-blowing furnace. The fuel is pulverized coal, which is sprayed into the melt by blowing. The back pressure of the spray gun is 0.2~0.35 Mpa, the oxygen combustion excess coefficient is 1.2, the melt temperature is 1400℃, and the oxygen enrichment concentration is 75%. Among them, the excess coefficient of oxygen combustion in oxidative smelting refers to the ratio of the actual amount of air supplied during fuel combustion to the theoretical amount of air.

The smelting products of the oxygen-enriched side-blown furnace include liquid high-phosphorus slag, molten dust and molten flue gas. Among them, the molten dust and molten flue gas are obtained by filtering and separating the furnace gas obtained by oxidation melting in the oxygen-enriched side-blown furnace. After adding pulverized coal, the phosphorus grade _P2O5 in the side-blown slag (liquid high-phosphorus slag) is _24.67 %. The molten flue gas is mainly _CO2 due to complete combustion, with a _CO2 volume fraction of 62.79%, which also includes some _{phosphorus P2O5} , and the _P2O5 volume fraction is only 0.1%. The side-blowing strengthens the oxidation combustion, and the _slag defluorination rate reaches 99%. Specifically, the volume fraction _{of SiF4} in the molten flue gas is 1.52%, the mass percentage of _CaF4 in the molten dust is 7.08%, and the F-containing substance _CaF4 in the liquid high-phosphorus slag is only 0.06%. Meanwhile, the melting fume also contains 0.01% by volume of H ₂ S and 0.26% by volume of SO ₂ . The melting fume contains 13.50% of P ₂ O ₅ , 7.08% of CaF ₂ , 0.2% of I and 1.66% of Cl.

The inputs in the side-blowing stage are: 0.21t coal per ton of ore, 279.61Nm ³ oxygen per ton of ore, 125.83Nm ³ compressed air per ton of ore, and 0.32t quartz stone per ton of ore; the output is 80.51% slag rate, 180.46kg side-blowing melting dust per ton of phosphorus, 1.50% dust rate, and 491.39Nm ³ flue gas per ton of ore.

(2) Reduction and acquisition of P ₂ O ₅

The liquid high-phosphorus slag is transferred into a side-blown reduction furnace, and a reducing agent coke with a particle size of 15-35 mm is sprayed into the molten pool by a spray gun, and the amount of coke added is 1.5 times the theoretical amount. The products of the reduction and volatilization phosphorus refining stage in the side-blown reduction furnace include dephosphorization slag, phosphorus-containing flue gas and _{ferrophosphorus} . At the same time, air is supplemented at the secondary combustion position of the furnace and the tertiary combustion position of the flue, so that the phosphorus-containing flue gas in the side-blown reduction furnace is converted into _P2O5 -containing smoke dust through the secondary combustion of the furnace and the tertiary combustion of the flue. The _P2O5 -containing smoke dust is separated to obtain _{the P2O5 -} containing _smoke gas and the volatile smoke dust, and the _P2O5 product is recovered through the _{P2O5 -} containing _smoke gas.

Among them, the content of _P2O5 in dephosphorization slag is only 0.46%, and the content of FeO is 0.04%; the flue gas containing _phosphorus before combustion is mainly CO and _N2 , with a volume fraction of CO of 42.03%, a volume fraction of _N2 of 52.16%, a volume fraction of phosphorus _P4 of 1.36%, a volume fraction of _H2S of only 0.08%, no HF, and a volume fraction of _SO2 of only 0.08%; the iron content in ferrophosphorus is 77.14%, and the P content is 18%. After combustion, the _flue gas containing _P2O5 is mainly _CO2 and _N2 , with a volume fraction of _CO2 of 19.07%, a volume fraction of _N2 of 75.32%, a volume fraction _{of P2O5} of 1.23%, no HF, and a volume fraction of CO of only 0.80%; the content _{of P2O5} in volatile smoke is 24.09%, and the content of _Fe2O3 is _1.63 %.

In the phosphorus refining stage of the side-blowing reduction furnace, 1.6t of coke is consumed per ton of phosphorus, the flue gas volume of the side-blowing reduction furnace per ton of phosphorus is 3300Nm ³ , 0.13t of ferrophosphorus is produced per ton of phosphorus, and 8.6kg of volatile smoke is generated per ton of phosphorus.

Since the volume fraction of CO in the _flue gas containing _P2O5 after combustion is only 0.800% and HF is 0.00%, the volatile elements and moisture in the liquid high-phosphorus slag have been removed in the side-blowing melting furnace, so that the flue gas of the side-blowing reduction furnace can be purified; therefore, the corrosiveness of the phosphorus-containing flue gas is reduced, avoiding the impact of the high corrosiveness of HF in the phosphorus-containing flue gas in the traditional electric furnace yellow phosphorus on the service life of the flue gas combustion equipment and pipelines. At the same time, the flue gas CO is completed through the furnace and flue air supply to achieve secondary combustion and tertiary combustion to maximize the calorific value. The CO combustion calorific value can be effectively used by the reduction furnace to maintain its reduction temperature and improve the phosphorus yield. In this step _{, the yield of P2O5 product} relative to the phosphorus in the liquid high-phosphorus slag is 93%.

Example 2

A method for producing yellow phosphorus by smelting phosphate ore, comprising:

(1) Obtaining liquid high-phosphorus slag

The phosphate rock and silica in Example 1 are mixed to obtain a mixture with a particle size of ≤50 mm and a mass ratio of acidity coefficient SiO ₂ /CaO of 0.65. The moisture content of the mixture is 2.8%. The mixture is added through the feeding port of the oxygen-enriched side-blown furnace. Pulverized coal is used as fuel. The pulverized coal is sprayed into the melt by blowing. The back pressure of the spray gun is 0.2-0.35 MPa, the oxygen combustion excess coefficient is 1.2, the melt temperature is controlled at 1500°C, and the oxygen enrichment concentration is 75%.

After adding pulverized coal, the phosphorus _{grade P2O5} in the side-blown slag (liquid high-phosphorus slag) is 26.85%. The flue gas is mainly _CO2 due to complete combustion, with a _CO2 volume fraction of 53%. The side-blowing strengthens the oxidative combustion, and the slag defluorination rate reaches 95%, and the _SiF4 volume fraction in the flue gas is 0.75%.

The inputs in the side-blowing stage are: 0.22t of coal per ton of ore, ^286Nm3 of oxygen per ton of ore, ^135Nm3 of compressed air per ton of ore, and 0.29t of quartz stone per ton of ore; the output is 78% slag rate, 193kg of side-blowing melting dust per ton of phosphorus, 1.56% dust rate, and ^520Nm3 of flue gas per ton of ore.

(2) Reduction and acquisition of P ₂ O ₅

The liquid high-phosphorus slag is transferred into the side-blown reduction furnace, and anthracite as a reducing agent is sprayed in. The amount of anthracite added is 1.65 times the theoretical amount, and the particle size of anthracite is 15-35 mm. The products of the reduction and volatilization phosphorus refining stage in the side-blown reduction furnace include dephosphorization slag, phosphorus-containing flue gas and ferrophosphorus; the phosphorus-containing flue gas in the side-blown reduction furnace undergoes secondary combustion in the furnace and tertiary combustion in the flue to convert the yellow phosphorus in the phosphorus-containing flue gas into _{P2O5 -} containing dust, and the _P2O5 product is recovered through the _{P2O5 - containing} dust.

The volume fraction of CO in the flue gas containing P ₂ O ₅ after combustion is only 0.65%, HF 0%, and P ₂ O ₅ 1.35%. In this step, the yield of P ₂ O ₅ product relative to phosphorus in liquid high-phosphorus slag is 96%.

In the reduction and volatilization phosphorus refining stage, 1.65t of anthracite is consumed per ton of phosphorus, the flue gas volume of the side-blowing reduction furnace is 3400Nm ³ , 0.135t of ferrophosphorus is produced per ton of phosphorus, and 7.95kg of volatilized smoke is generated per ton of phosphorus.

Example 3

A method for producing yellow phosphorus by smelting phosphate ore, comprising:

(1) Obtaining liquid high-phosphorus slag

The phosphate rock and silica in Example 1 are mixed to obtain a mixture with a particle size of ≤50 mm and an acidity coefficient SiO ₂ /CaO of 0.85. The moisture content of the mixture is 3.2%. The mixture is added through the feeding port of the oxygen-enriched side-blown furnace. Pulverized coal is used as fuel. The pulverized coal is sprayed into the melt by blowing. The back pressure of the spray gun is 0.2-0.35 MPa, the oxygen combustion excess coefficient is 1.2, the melt temperature is controlled to be 1350°C, and the oxygen enrichment concentration is 75%.

After adding pulverized coal, the phosphorus grade P ₂ O ₅ in the side-blown slag (liquid high-phosphorus slag) is 23.58%. The flue gas is mainly CO ₂ due to complete combustion, and the volume fraction of CO ₂ is 65%. The side-blowing strengthens the oxidative combustion, and the slag defluorination rate reaches 94%, and the volume fraction of SiF ₄ in the flue gas is 1.35%. The input of the side-blowing stage is: 0.22t of coal per ton of ore, 290 Nm ³ of oxygen per ton of ore, 135 Nm ³ of compressed air per ton of ore, and 0.35 t of quartz stone per ton of ore; the output is 85% of slag rate, 195kg of side-blown melting dust per ton of phosphorus, 1.65% of dust rate, and 530Nm ³ of flue gas per ton of ore.

(2) Reduction and acquisition of P ₂ O ₅

The liquid high-phosphorus slag is transferred into the side-blown reduction furnace, and anthracite as a reducing agent is sprayed in. The amount of anthracite added is 1.8 times the theoretical amount, and the particle size of anthracite is 15-35 mm. The products of the reduction and volatilization phosphorus refining stage in the side-blown reduction furnace include dephosphorization slag, phosphorus-containing flue gas and ferrophosphorus; the phosphorus-containing flue gas in the side-blown reduction furnace undergoes secondary combustion in the furnace and tertiary combustion in the flue to convert the yellow phosphorus in the phosphorus-containing flue gas into _{P2O5 -} containing dust, and the _P2O5 product is recovered through the _{P2O5 - containing} dust.

The volume fraction of CO in the flue gas containing P ₂ O ₅ after combustion is only 0.60%, HF 0%, and P ₂ O ₅ 1.15%. In this step, the yield of P ₂ O ₅ product relative to phosphorus in liquid high-phosphorus slag is 93%.

In the reduction and volatilization phosphorus refining stage, 1.73t of anthracite is consumed per ton of phosphorus, the flue gas volume of the side-blowing reduction furnace is 3600Nm ³ , 0.12t of ferrophosphorus is produced per ton of phosphorus, and 9.5kg of volatilized smoke is generated per ton of phosphorus.

Example 4

A method for producing yellow phosphorus by smelting phosphate ore, comprising:

(1) Obtaining liquid high-phosphorus slag

The phosphate rock and silica in Example 1 are mixed to obtain a mixture with a particle size of ≤50 mm and a mass ratio of acidity coefficient SiO ₂ /CaO of 0.80. The moisture content of the mixture is adjusted to 10%, and the mixture is added through the charging port of the oxygen-enriched side-blowing furnace. Pulverized coal is used as fuel, and the pulverized coal is sprayed into the melt by blowing. The back pressure of the spray gun is 0.2-0.35 MPa, the oxygen combustion excess coefficient is 1.2, the melt temperature is controlled to be 1450°C, and the oxygen enrichment concentration is 75%.

After adding pulverized coal, the phosphorus grade P ₂ O ₅ in the side-blown slag (liquid high-phosphorus slag) is 25.50%. The flue gas is mainly CO ₂ due to complete combustion, and the volume fraction of CO ₂ is 68.35%. The side-blowing strengthens the oxidative combustion, and the slag defluorination rate reaches 96%, and the volume fraction of SiF ₄ in the flue gas is 1.15%. The input of the side-blowing stage is: 0.23t of coal per ton of ore, 290 Nm ³ of oxygen per ton of ore, 135 Nm ³ of compressed air per ton of ore, and 0.33 t of quartz stone per ton of ore; the output is 83% of slag rate, 185kg of side-blown melting dust per ton of phosphorus, 1.55% of dust rate, and 550Nm ³ of flue gas per ton of ore.

(2) Reduction and acquisition of P ₂ O ₅

The liquid high-phosphorus slag is transferred into the side-blown reduction furnace, and the reducing agent coke is sprayed in. The amount of coke added is 1.95 times the theoretical amount, and the coke particle size is 15-35 mm. The products of the reduction and volatilization phosphorus refining stage in the side-blown reduction furnace include dephosphorization slag, phosphorus-containing flue gas and ferrophosphorus; the phosphorus-containing flue gas in the side-blown reduction furnace undergoes secondary combustion in the furnace and tertiary combustion in the flue to convert the yellow phosphorus in the phosphorus-containing _flue gas into _P2O5 -containing dust, and the _P2O5 product is recovered through the _{P2O5 - containing} dust.

The volume fraction of CO in the flue gas containing P ₂ O ₅ after combustion is only 0.55%, HF 0%, and P ₂ O ₅ 1.05%. In this step, the yield of P ₂ O ₅ product relative to phosphorus in liquid high-phosphorus slag is 92%.

In the reduction and volatilization phosphorus refining stage, 1.75t of coke is consumed per ton of phosphorus, the flue gas volume containing phosphorus per ton of phosphorus is 3800Nm ³ , 0.12t of ferrophosphorus is produced per ton of phosphorus, and 9.5kg of volatilized dust is generated per ton of phosphorus.

Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims (10)

1. A method of melt producing P ₂O₅ comprising: obtaining liquid high-phosphorus slag, adding a reducing agent into the liquid high-phosphorus slag for reduction to obtain phosphorus-containing flue gas, converting the phosphorus-containing flue gas into P ₂O₅ smoke dust through combustion, and recovering a P ₂O₅ product through the P ₂O₅ smoke dust; it is characterized in that the method comprises the steps of,

The liquid high-phosphorus slag is obtained in an oxidation smelting furnace, and the addition and combustion transformation of the reducing agent are carried out in the reduction furnace;

the liquid high-phosphorus slag is obtained through the following steps: and mixing the phosphate ore and the slag-forming flux to obtain a mixed material with an acidity coefficient of 0.65-0.85, and carrying out oxidation smelting on the mixed material to obtain molten liquid high-phosphorus slag.

2. The method of claim 1, wherein the phosphorus-containing flue gas is directly post-combusted in a hearth of the reduction furnace and three combustions in a flue of the reduction furnace convert yellow phosphorus in the phosphorus-containing flue gas to P ₂O₅ -containing flue gas.

3. The method according to claim 1 or 2, wherein the water content of the mixed material is 12% or less;

And/or the particle size of the mixed material is less than or equal to 50mm;

And/or, the addition amount of the reducing agent in the liquid high-phosphorus slag is more than 1 time of the theoretical amount.

4. The method of claim 3, wherein the water content of the mixed material is 2% -5%;

and/or the addition amount of the reducing agent in the liquid high-phosphorus slag is 1-2 times of the theoretical amount.

5. The method according to claim 1 or 2, characterized in that the temperature of the oxidation smelting is 1350-1500 ℃.

6. The method of claim 1 or 2, wherein the reductant comprises at least one of anthracite, semi-coke, graphite powder, and coke.

7. The method according to claim 1 or 2, characterized in that the particle size of the reducing agent is 15-35 mm.

8. A system based on a method for melt production of P ₂O₅ according to any one of claims 1 to 7, characterised in that it comprises:

the oxidation smelting furnace is used for oxidizing and smelting the phosphate ore and the slag-forming flux into molten liquid high-phosphorus slag;

The reducing furnace comprises a liquid high-phosphorus slag input port, a reducing material input port and a flue gas outlet, and is used for reducing the liquid high-phosphorus slag to obtain phosphorus-containing flue gas;

And the combustion devices are respectively arranged in the reduction furnaces and are used for converting yellow phosphorus into P ₂O₅ through combustion.

9. The system of claim 8, wherein the combustion device is disposed on a hearth and flue of a reduction furnace.

10. The system of claim 8 or 9, wherein the reduction furnace is a side-blown reduction furnace;

and/or the oxidation smelting furnace is a side-blowing furnace, a top-blowing furnace, a bottom-blowing furnace, a top-side combined-blowing furnace and a top-bottom combined-blowing furnace.