CN113753864B - Method for producing sulfuric acid and co-producing slag cotton fiber from high-impurity phosphogypsum - Google Patents

Abstract

The invention proposes a method for producing sulfuric acid and co-producing slag wool fibers from high-impurity phosphogypsum. According to the characteristics of phosphogypsum with high impurity content such as silicon, aluminum, magnesium, etc., calculation and batch optimization are carried out. After reduction, roasting, decomposition and melting, the sulfur contained in phosphogypsum is reduced to SO ₂ , which can be used to produce sulfuric acid. The by-product molten slag can be directly prepared into slag wool fiber products with high added value through wire drawing, blowing or centrifuging process. While the S element in phosphogypsum is recycled and utilized, the higher silicon and aluminum content in phosphogypsum can be recycled. , magnesium and other impurity components are converted into raw materials for the preparation of slag wool, which can save silicon, calcium and other raw materials required for slag wool, realize high value-added utilization of phosphogypsum cinder, and make the phosphogypsum acid production technology more economical and competitive , with outstanding technical effects.

Description

Method for producing sulfuric acid and co-producing slag cotton fiber from high-impurity phosphogypsum

technical field

The invention relates to the technical field of producing sulfuric acid from phosphogypsum and the high-value utilization of slag, in particular to a method for co-producing slag cotton fiber by producing sulfuric acid from high-impurity phosphogypsum.

Background technique

Phosphogypsum is an industrial by-product of wet process production of phosphoric acid, and 4.5t-5.5t of phosphogypsum is produced for every 1t of phosphoric acid produced. The main component of phosphogypsum is CaSO ₄ ·2H ₂ O, and contains relatively SiO ₂ and a small amount of MgO, Al ₂ O ₃ , Fe ₂ O ₃ , P ₂ O ₅ , fluoride, organic matter and other impurities. The current stock of phosphogypsum in China is as high as about 750 million tons, with an annual increase of about 90 million tons, and the comprehensive utilization and disposal rate is less than 40%. A huge amount of phosphogypsum is concentrated in a special slag storage, which brings environmental protection and safety risks. The state has not allowed new phosphogypsum slag storage. , especially for the comprehensive utilization rate of phosphogypsum, higher and higher requirements are put forward, and enterprises that fail to meet the utilization rate requirements face the risk of shutting down; on the other hand, a series of policy documents have been issued to encourage and strengthen bulk solid waste and phosphogypsum Comprehensive utilization. Therefore, the comprehensive utilization of phosphogypsum has become a major problem that restricts the sustainable and healthy development of my country's wet-process phosphoric acid and high-concentration phosphate compound fertilizer industries.

At present, the by-product phosphogypsum in the domestic wet-process phosphoric acid and phosphorus compound fertilizer industry is still mainly stored in slag storage, and its comprehensive utilization rate, especially resource utilization rate, is still at a low level, and the main utilization method is still processing low-end products In the primary stage, such as the preparation of cement retarder, modified for mine filling, processing construction gypsum and other building materials (various powder materials and profiles). In terms of phosphogypsum acid production, compared with the mainstream method of sulfur acid production, the production cost is high, and a large amount of slag can only be used as low-end products such as cement clinker or admixture, and the quality fluctuates greatly, the added value is low, and it is not economical. Sex and competitiveness, so it is difficult to apply and promote on a large scale. Except for a few units that can maintain production due to the consideration of the treatment of industrial waste, other phosphogypsum acid production co-production cement units have been shut down successively.

Slag cotton fiber belongs to inorganic silicate fiber. It is a kind of cotton filament mineral fiber produced by centrifugation/injection method with molten slag as the main raw material. It is a high value-added product. The market price of slag wool is about 2,200 yuan/t or more, and the price of some high-temperature-resistant slag wool heat insulation board products such as metallurgy, chemical industry, and electric power is more than 10,000 yuan/t. At present, solid slags such as blast furnace slag and yellow phosphorus slag from high-temperature ironmaking are mainly used in China to produce slag wool by tempering the slag, homogenizing (insulating), and centrifuging into fibers.

Patent CN102530886B discloses a method for preparing sulfuric acid and cement from phosphogypsum by adding sand, coke, lime, coarse salt and ferrous salt to phosphogypsum, adding it to a rotary kiln for calcination, and decomposing the obtained _SO2 flue gas It is used to make sulfuric acid, and the cinder is used as cement clinker.

Phosphogypsum production of acid and co-production of cement is an important way to realize the large-scale digestion and utilization of phosphogypsum in the wet-process phosphoric acid and phosphate compound fertilizer industry itself. Due to reasons such as poor economy, it is difficult to popularize and apply, which has become a major problem to be solved urgently.

Contents of the invention

The present invention just aims at the common problem of co-production of cement with sulfuric acid from phosphogypsum at present, and proposes a method for co-production of slag cotton fiber with high-impurity phosphogypsum production of sulfuric acid. According to the characteristics of phosphogypsum with high impurity content such as silicon, the calculation and batching optimization are carried out. Through reduction, roasting, melting and other processes, the sulfur contained in phosphogypsum is reduced to generate high-concentration SO ₂ , which is used to make sulfuric acid. The by-product molten slag can be directly prepared into slag wool fiber products by blowing or centrifuging process. While the S element in phosphogypsum is recycled and utilized, the high value-added utilization of slag is realized. At the same time, phosphogypsum can also be fully utilized The relatively high silicon and some aluminum, magnesium and other impurity components can be effectively transformed into raw materials for the preparation of slag cotton fibers, further reducing and saving other minerals such as silicon ore and other solid waste materials with higher value such as fly ash, and reducing production. Reduce the cost and reduce the impact of mineral mining such as silicon on the environment, making acid production with phosphogypsum more economical and ecologically beneficial, and conducive to the large-scale promotion and application of phosphogypsum in the chemical industry.

Based on the purpose of the present invention, proposed the method for high-impurity phosphogypsum system sulfuric acid co-production slag cotton fiber, comprises the steps:

(1) Add the compound raw materials containing silicon, aluminum and magnesium to the high-impurity phosphogypsum to meet the control requirement that the acidity coefficient Mk is 1.1-1.5, and the pH value is 4-5;

(2) adding carbon-based reducing materials after pulverizing the mixture in step (1); wherein the molar ratio of C in the carbon-based reducing materials to S in phosphogypsum is 0.5-1.0:1;

(3) Add a high-temperature-resistant binder to the material obtained in step (2), fully mix it uniformly, prepare the material into a shape, send it into a high-temperature reaction furnace, and perform reduction, roasting and melting in sequence;

Among them: the temperature control range of the reducing layer is 750-880°C, the average residence time is 3.0-30.0 minutes; the temperature control range of the firing layer is 1150-1280°C, the firing time is 2.0-20.0 minutes, the temperature control range of the melting layer is 1320-1550°C, and the melting time In 1.0-8.0 minutes, the generated molten slag is sprayed or centrifuged to prepare slag wool fibers; the viscosity of the molten slag is 1-3 Pa·s.

(4) The high-concentration _SO2 flue gas generated by the reaction. The _SO2 flue gas discharged from the upper part of the furnace, after cyclone dust removal, waste heat recovery and washing purification, is sent to the sulfuric acid system to make acid, and the sulfur in phosphogypsum decomposes and escapes The rate is 95-98%.

High-impurity phosphogypsum refers to phosphogypsum with high silicon content and a certain amount of aluminum and magnesium. The high-impurity phosphogypsum in the present invention is phosphogypsum containing more silicon and impurities such as aluminum and magnesium at the same time. The compound raw materials of silicon, aluminum and magnesium are supplemented to further increase the content of silicon, aluminum and magnesium in the phosphogypsum to meet the requirements of phosphorous gypsum. Ingredients requirements for slag wool fibers made from gypsum.

The reaction principle is;

Reducing layer: CaSO ₄ +2C=CaS+CO ₂ (endothermic reaction)

CaSO ₄ +4CO＝CaS+4CO ₂ (endothermic reaction)

CaSO ₄ +CO＝CaO+CO ₂ +SO ₂ (exothermic reaction)

Baked layer: 2CaS+3O ₂ == 2CaO+2SO ₂ (exothermic reaction)

CaS+3CaSO ₄ ＝4CaO+4SO ₂ (endothermic reaction)

2CaSO ₄ ＝2CaO+O ₂ +2SO ₂ (endothermic reaction)

In the present invention, the main component of phosphogypsum is calcium sulfate. According to the contents of CaO, SiO ₂ , Al ₂ O ₃ , and MgO in silicide, aluminide, magnesium compound and phosphogypsum, Mk is 1.1-1.5, and the pH value is 4-5, optimize and determine the respective ingredients.

The viscosity of molten slag has a certain relationship with temperature. At higher temperature, the viscosity is smaller and the fluidity is better. When the temperature drops to a certain level, the viscosity increases sharply, and the fluidity is relatively poor. The reasonably optimized melt viscosity for preparing slag wool is 1-3 Pa·s, and the corresponding range temperature is about 1270-1550°C, which can meet the requirements for preparing slag wool. When the acidity coefficient Mk of molten slag is 1.2-1.5, the fiber diameters are all less than 6.0 μm, and the range of change is not large. With the increase of Mk, the diameter of slag wool tends to increase slightly. And the slag ball content (mass fraction) in the slag wool increases with the increase of the acidity coefficient. When the acidity coefficient increases to 1.5, the content is 5.02%, which is within the range of the national standard (≤7%).

Preferably, the molding is prepared by adding a binder, which is in the shape of a cylinder, a rod, a ball, a rugby ball, and the like. Organic binders and inorganic binders can be used. Inorganic binders can be selected from bentonite, kaolin, cement, water glass, quicklime, etc., and organic binders can be selected from coal tar, high molecular polymers (polyvinyl alcohol, phenolic resin, etc.) , CMC), starch, lignocellulose, etc., organic and inorganic composites can be used when necessary.

Preferably, the high-concentration SO _flue gas generated by the reaction in the present invention is discharged from the upper part of the flue gas, after cyclone dust removal, waste heat recovery, and purification, it is sent to the sulfuric acid system to make acid, and the decomposition and escape rate of sulfur in phosphogypsum is 95-98%.

Preferably, the temperature of the reduction layer of phosphogypsum is about 850°C, the residence time is 5 minutes, and the reaction product is mainly a mixture of CaS, CaSO ₄ and silicon compounds.

Preferably, the temperature of the calcined layer is about 1220°C, the residence time is 5 minutes, and the reaction products are mainly multi-phase slag (mainly containing Ca, Si, Al, Mg, etc.) and SO ₂ flue gas.

Preferably, the melting layer temperature is 1450° C., and the residence time is 4 minutes.

The pH value in the present invention is a more accurate index to measure the chemical stability of rock wool and slag wool.

In the aforementioned method for producing sulfuric acid from phosphogypsum with high impurities and co-producing slag wool fibers, 0.2-15% by mass of sulfur powder is added in step (1).

This step can also be replaced by injecting sulfur liquid of the same concentration into the high-temperature reaction furnace in step (3).

The aforementioned method for producing sulfuric acid from phosphogypsum with co-production of slag cotton fiber with high impurities, the carbon-based reducing material is a carbon-based (C) reducing agent, selected from one or more of lignite, anthracite, coke, coke, white coal .

In the aforementioned method of using phosphogypsum to make acid and co-produce slag cotton fiber, the mixture in step (2) is pulverized and passed through a 30-80 mesh sieve.

In the aforementioned method for producing sulfuric acid co-production of slag wool fiber from high-impurity phosphogypsum, the silicide is selected from one or more of silica powder, fly ash, coke ash, blast furnace slag, and potassium feldspar.

In the aforementioned method for producing sulfuric acid and co-producing slag wool fibers from high-impurity phosphogypsum, the aluminide is selected from one or more of fly ash, coke ash, and blast furnace slag.

In the aforementioned method for producing sulfuric acid and co-producing slag wool fibers from high-impurity phosphogypsum, the magnesium compound is selected from one or both of boron-magnesite ore and blast furnace slag.

The aforementioned method for producing sulfuric acid from high-impurity phosphogypsum and co-producing slag wool fiber, the mass percent content of the main components of slag wool fiber is SiO ₂ 36-42%, Al ₂ O ₃ 5-12%, CaO 28-47%, MgO 1-12%, _Fe2O3 1-5%, _R2O 0-1.2 _% .

The method for the aforementioned high-impurity phosphogypsum system sulfuric acid co-production slag cotton fiber, the acidity coefficient Mk is the mass ratio of contained acidic oxides and basic oxides,

Mk=(W _SiO2 +W _Al2O3 )/(W _CaO +W _MgO ).

The method for the above-mentioned high-impurity phosphogypsum system sulfuric acid co-production slag cotton fiber, the calculation method of pH value is:

pH=-0.0602W _SiO2 -0.120W _Al2O3 +0.232W _CaO +0.120W _MgO +0.144W _Fe2O3 +0.21W _Na2O .

Through the above technical scheme, the present invention proposes a method for producing sulfuric acid co-production slag cotton fiber from high-impurity phosphogypsum, which has the following advantages:

According to the characteristics of phosphogypsum with high silicon content and impurities such as aluminum and magnesium, the calculation and batching optimization are carried out. Through reduction, roasting, melting and other processes, the sulfur contained in phosphogypsum is reduced to generate SO ₂ flue gas, which is used for the production of At the same time as sulfuric acid, the obtained by-product molten slag can be directly prepared into slag wool fiber products through injection or centrifugal process. While the S element in phosphogypsum is recycled and utilized, the high value-added utilization of slag is realized. In addition, it can also make full use of the relatively high silicon contained in phosphogypsum, as well as impurities such as aluminum and magnesium, and turn impurities into raw materials for preparing slag wool, further saving other mineral resources or other solid waste materials with higher value, and reducing production costs. , reduce the impact of mineral mining such as silicon on the environment, make acid production with phosphogypsum more economical and ecologically beneficial, and be conducive to the large-scale promotion and application of phosphogypsum in the chemical industry.

Description of drawings

The above and/or additional aspects and advantages of the present invention will become apparent and easy to understand from the following description of the embodiments in conjunction with the accompanying drawings, wherein:

Fig. 1 is the process flowchart of the method for producing sulfuric acid co-production slag cotton fiber from high-impurity phosphogypsum provided in Example 1.

Detailed ways

In order to more clearly understand the purpose of the present invention, the features and advantages of the technical solution, etc., the present invention will be described in detail below in conjunction with specific embodiments and accompanying drawings, but the present invention can also adopt methods different from those described in the following embodiments It should be understood that the embodiments described here are only used to explain the present invention, not to limit the present invention, and all changes made based on the derivation of the present invention shall belong to the protection scope of the present invention. In the case of no conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

Example

As shown in Fig. 1, the present embodiment proposes the method for high impurity phosphogypsum system sulfuric acid co-production slag cotton fiber, comprises the following steps:

(1) Add silicides, aluminides, and magnesium compounds into phosphogypsum with high silicon content and impurities such as aluminum and magnesium, and control the acidity coefficient Mk at 1.1-1.5 and the pH value at 4-5; The compound is selected from one or more of silica powder, fly ash, coke ash, blast furnace slag, and potassium feldspar; the aluminide is selected from one or more of fly ash, coke ash, and blast furnace slag; One or two selected from boron magnesium ore or blast furnace slag.

The acidity coefficient Mk is the mass ratio of acidic oxides and basic oxides contained in the material,

Mk＝(W _SiO2 +W _Al2O3 )/(W _CaO +W _MgO ); the calculation method of pH value is:

pH=-0.0602W _SiO2 -0.120W _Al2O3 +0.232W _CaO +0.120W _MgO +0.144W _Fe2O3 +0.21W _Na2O .

(2) After pulverizing the mixture in step (1), pass through a 30-80 mesh sieve, and add carbon-based reducing materials; wherein the molar ratio of carbon (C) in the carbon-based reducing materials to sulfur (S) in phosphogypsum It is 0.5-1.0:1; the reducing material is carbon (C) reducing agent, which is selected from one or more of lignite, anthracite, coke, coke, and white coal.

(3) Add a binder to the mixture obtained in step (2) to prepare a molding, send it into a high-temperature reaction furnace, and perform reduction, roasting and melting in sequence.

Among them: the temperature of the reduction layer is controlled to be 750-880°C, the residence time is 3.0-30.0 minutes, and the main reaction principle is:

Reduction: CaSO ₄ +2C=CaS+CO ₂ (endothermic reaction); CaSO ₄ +4CO=CaS+4CO ₂ (endothermic reaction); CaSO ₄ +CO=CaO+CO ₂ +SO ₂ (exothermic reaction);

Among them: the temperature of the roasting layer is controlled at 1150-1280°C, the residence time is 2.0-20.0 minutes, and the main reaction principle is: 2CaS+3O ₂ == 2CaO+2SO ₂ (exothermic reaction);

CaS+3CaSO ₄ =4CaO+4SO ₂ (endothermic reaction);

2CaSO ₄ ＝2CaO+O ₂ +2SO ₂ (endothermic reaction)

Among them: the temperature of the molten layer is controlled at 1320-1550°C, the residence time is 1.0-8.0 minutes, and the molten slag is blown or centrifuged to obtain slag wool fibers; the viscosity of the molten slag is 1-3Pa·s.

The main component of phosphogypsum in the present invention is calcium sulfate, according to the content of CaO, MgO, SiO ₂ , Al ₂ O ₃ in silicides, aluminides and magnesium compounds and phosphogypsum, according to Mk, it is 1.1-1.5 , PH value is 4-5, determine the respective ingredients. The main technical indicators of the slag wool prepared by the present invention: meet the requirements of GB/T 11835-2016, mainly inspecting that the average fiber diameter is ≤6.0 μm, and the content of slag balls with a particle size ≥0.25 mm should be ≤7.0%.

Preferably, the step of preparing slag wool fibers by blowing or centrifuging molten slag is:

The blowing experiment device mainly consists of a DC electric arc furnace, a diversion tank, and a high-speed airflow spray gun. The electric arc furnace adopts graphite electrode to start the arc, and the melting capacity is 100kg/h; the nozzle adopts Raoult tube design, and the maximum wind pressure is 0.45MPa. After the molten slag is smelted by the electric arc furnace, it is transported to the nozzle of the high-speed air flow through the diversion groove, and the fibers formed by the blowing are collected under the action of the cotton collection system. Injection fiber forming is a process in which continuous blast furnace slag melt is crushed by high-speed airflow to form fibers.

Centrifugal preparation of slag wool fibers: molten slag drips through the diversion tank to the centrifuge to form fibers, and the fibers are further processed into panels through subsequent processes such as sizing, cotton collection, board forming, and solidification treatment. The slag wool product produced by online direct fiberization of molten slag is made by spinning blast furnace slag directly through a high-speed rotating four-roller centrifuge, then spraying an appropriate amount of binder, and then forming, drying, and curing processes. The fiber forming device mainly includes DC electric arc furnace, diversion tank, four-roll centrifuge, etc.

The diameters of the four rolls of the four-roller centrifuge are 213, 295, 295, and 295mm respectively, and the speeds of the four rolls during the test are: 2707, 3093, 4350, 5800r/min. Or the diameters of the four rollers of the four-roller centrifuge are 1#213mm, 2#295mm, 3#295mm, 4#295mm, and the four-roller speeds during the experiment are: 1#2070-3000r/min, 2#3093-4000r/min, 3#4350-4500r/min, 4#5000-5800r/min. Like the injection method, the molten slag is transported to the centrifuge through the diversion groove, and the formed slag wool enters the settling chamber under the action of the fiber-forming blower and the cotton-collecting induced draft fan. The mass percent content of the main components of the obtained slag wool fiber is SiO ₂ 36-42%, Al ₂ O ₃ 9-17%, CaO 28-47%, MgO 3-12%, Fe ₂ O ₃ 1-5% , R ₂ O 0-1.2% and other components are excluded.

(4) The high-concentration _SO2 flue gas generated by the reaction is discharged from the upper part and sent to the acid plant for acid production. The sulfur escape rate in phosphogypsum is 95-98%.

Example 1

The composition of raw materials used in this example and the following examples is shown in Table 1.

Raw material composition (mass fraction %) used in the embodiment of table 1

100 mass parts of phosphogypsum, 18.5 mass parts of fly ash, 8 mass parts of iron tailings and 10 mass parts of silica are crushed through a 40-mesh sieve, according to the moles of sulfur (S) in carbon (C) and phosphogypsum When the ratio is 0.8, 7.2 parts by mass of coke (with a fixed carbon content of 63.62%) is added, and the acidity index MK=1.32 and pH=4.40 of the batching meet the batching requirements of slag rock wool. All raw materials are mixed evenly and added with binder to make rod-shaped profiles, which are sent to a high-temperature reaction furnace for reduction, roasting and melting in sequence; the temperature of the reduction layer is controlled at 850°C, the average residence time of materials is 10.0 minutes, and the temperature of the roasting layer is 1220°C. The average residence time of the material is 5.0 minutes, the temperature of the molten layer is 1450°C, and the average residence time of the material is 4.0 minutes. The generated molten slag is sprayed to prepare slag wool fibers; the viscosity of the molten slag is 1.8Pa·s. The escape rate of sulfur in phosphogypsum is 97%, and the mass fraction of _SO2 in the flue gas generated by the reaction is 7.5%. The flue gas is discharged from the upper part, and after dust removal, waste heat recovery and washing purification, it is sent to the sulfuric acid system to make acid , the molten slag is discharged from the lower part, and the slag wool is prepared by the injection process. The content of each component in the prepared slag wool: CaO 29.60%, SiO ₂ 34.91%, Al ₂ O ₃ 5.89%, MgO 1.37%, Fe ₂ O ₃ 1.0%, Na ₂ O 0.19%, moisture content 0.73%, fiber diameter 4.8μm, slag ball content 0.73%.

Example 2

The phosphogypsum of 100 mass parts, the fly ash of 22.5 mass parts, the iron tailings of 25 mass parts are pulverized through 40 mesh sieves, and according to the molar ratio of sulfur (S) in charcoal (C) and phosphogypsum, be 0.9 to add coke ( The fixed carbon content is 65.1%) 8.0 parts by mass, the acidity index MK=1.46, pH=4.29 of the batching, which meet the batching requirements of slag rock wool. All raw materials are mixed evenly and added with binder to make rod-shaped profiles, which are sent to a high-temperature reaction furnace for reduction, roasting, oxidation and melting in sequence; among them: the temperature of the reduction layer is controlled at 830°C, the average residence time of materials is 15.0 minutes, and the temperature of the roasting layer is 1200°C, the average residence time of the material is 10.0 minutes, the temperature of the molten layer is 1400°C, the average residence time of the material is 6.0 minutes, the molten slag is generated and sprayed to prepare slag wool fibers; the viscosity of the molten slag is 2.1Pa·s. The escape rate of sulfur in phosphogypsum is 95%, and the mass fraction of _SO2 in the flue gas generated by the reaction is 7.2%. The flue gas is discharged from the upper part, and after dust removal, waste heat recovery and washing purification, it is sent to the sulfuric acid system to make acid , the molten slag is discharged from the lower part, and the slag wool is prepared by the injection process. The content of each component in the prepared slag wool: CaO 30.14%, SiO ₂ 39.87%, Al ₂ O ₃ 7.44%, MgO 2.24%, Fe ₂ O ₃ 1.77%, Na ₂ O 0.34%, moisture content 0.61%, fiber The diameter is 4.2μm, and the slag content is 3.18%.

Example 3

The phosphogypsum of 100 mass parts, the fly ash of 17 mass parts, the iron tailings of 10 mass parts and the silica of 15 mass parts are pulverized through 40 mesh sieves, according to the mole of sulfur (S) in carbon (C) and phosphogypsum When the ratio is 0.85, 7.2 parts by mass of coke (68.21% of fixed carbon content) is added, and the acidity index MK=1.47 and pH=4.15 of the batching meet the batching requirements of slag rock wool. Mix all raw materials evenly and add binder to make a rod-shaped profile, send it into a high-temperature reaction furnace, and perform reduction, roasting and melting in sequence; among them: the temperature of the reduction layer is controlled at 780°C, the average residence time of the material is 18.0 minutes, and the temperature of the roasting layer is 1250 °C, the average residence time of the material is 4.0 minutes, the temperature of the molten layer is 1550 °C, the average residence time of the material is 3.0 minutes, the molten slag is generated and sprayed to prepare slag wool fibers; the viscosity of the molten slag is 2.3Pa·s. The escape rate of sulfur in phosphogypsum is 96%, and the mass fraction of _SO2 in the flue gas generated by the reaction is 7.8%. The flue gas is discharged from the upper part, and after dust removal, waste heat recovery and washing purification, it is sent to the sulfuric acid system to make acid , sent to the acid system, the molten slag is discharged from the lower part, and the slag wool is prepared by the injection process. The content of each component in the prepared slag wool: CaO 29.67%, SiO ₂ 40.08%, Al ₂ O ₃ 5.70%, MgO 1.38%, Fe ₂ O ₃ 1.09%, Na ₂ O 0.22%, moisture content 2%, fiber diameter 5.8μm, slag ball content 4.21%.

Example 4

Add 5% sulfur powder in step (1), the mass fraction of SO in _the flue gas generated by the reaction is 9%, the flue gas is discharged from the top, after dust removal, waste heat recovery and washing and purification, it is sent to the sulfuric acid system to make acid , the molten slag is discharged from the lower part, and the slag wool is prepared by the injection process. Other technical features of this embodiment are the same as those of Embodiment 1, and will not be repeated here.

Comparative example 1

The phosphogypsum of 100 mass parts, the fly ash of 15 mass parts, the iron tailings of 5 mass parts are pulverized through 40 mesh sieves, according to the molar ratio of sulfur (S) in charcoal (C) and phosphogypsum is 0.8 and adds coke ( The fixed carbon content is 63.62%) 7.2 mass parts, the acidity index MK=0.9 of this batching, pH=5.1. All raw materials are mixed evenly and added with binder to make rod-shaped profiles, which are sent to a high-temperature reaction furnace for reduction, roasting and melting in sequence; the temperature of the reduction layer is controlled at 850°C, the average residence time of materials is 10.0 minutes, and the temperature of the roasting layer is 1220°C. The average residence time of the material is 5.0 minutes, the temperature of the molten layer is 1450° C., the average residence time of the material is 4.0 minutes, and the viscosity of the molten slag is 1.8 Pa·s. The escape rate of sulfur in phosphogypsum is 97%, and the mass fraction of _SO2 in the flue gas generated by the reaction is 7.5%. The flue gas is discharged from the upper part, and after dust removal, waste heat recovery and washing purification, it is sent to the sulfuric acid system to make acid , the molten slag is discharged from the lower part, and the content of each component of the slag: CaO 29.07%, SiO ₂ 22.69%, Al ₂ O ₃ 4.45%, MgO 1.02%, Fe ₂ O ₃ 0.67%, Na ₂ O 0.14%, cannot form a good Vitreous structure, unable to prepare slag wool.

Comparative example 2

The phosphogypsum of 100 mass parts, the fly ash of 22.5 mass parts, the iron tailings of 35 mass parts are pulverized and crossed 40 mesh sieves, according to the molar ratio of sulfur (S) in charcoal (C) and phosphogypsum, add coke ( The fixed carbon content is 63.62%) 7.2 mass parts, the acidity index MK=1.66 of this batching, pH=4.01. All raw materials are mixed evenly and added with binder to make rod-shaped profiles, which are sent to a high-temperature reaction furnace for reduction, roasting and melting in sequence; the temperature of the reduction layer is controlled at 850°C, the average residence time of materials is 10.0 minutes, and the temperature of the roasting layer is 1220°C. The average residence time of the material is 5.0 minutes, the temperature of the molten layer is 1450° C., the average residence time of the material is 4.0 minutes, and the viscosity of the molten slag is 3.1 Pa·s. The escape rate of sulfur in phosphogypsum is 97%, and the mass fraction of _SO2 in the flue gas generated by the reaction is 7.5%. The flue gas is discharged from the upper part, and after dust removal, waste heat recovery and washing purification, it is sent to the sulfuric acid system to make acid , the molten slag is discharged from the lower part, and the slag wool is prepared by the injection process. The content of each component in the prepared slag wool: CaO 30.44%, SiO ₂ 47.07%, Al ₂ O ₃ 7.93%, MgO 2.65%, Fe ₂ O ₃ 2.25%, Na ₂ O 0.43%, moisture content 2.5%, fiber The diameter is 8.2 μm, and the slag ball content is 4.21%, which cannot meet the index requirements of slag wool products.

The above are only examples of preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, improvement, equivalent replacement, etc. made within the principle of creativity and innovation of the present invention shall belong to the protection scope of the present invention.

Claims (6)

1. a method for high-impurity phosphogypsum system sulfuric acid co-production slag wool fiber, is characterized in that at least comprising the steps: (1) Add compounds containing silicon, aluminum, and magnesium to high-impurity phosphogypsum, control the acidity coefficient MK to 1.1-1.5, and the pH value to 4-5; and add 0.2-15% by mass of sulfur powder; silicification The compound is selected from one or more of silica powder, fly ash, coke ash, blast furnace slag, and potassium feldspar; the aluminide is selected from one or more of fly ash, coke ash, and blast furnace slag; (2) Add carbon-based reducing materials after pulverizing the mixture in step (1); wherein the molar ratio of C in the reducing materials to S in phosphogypsum is 0.5-1.0:1; (3) In the material obtained in step (2), add a high-temperature-resistant binder for molding, and send it into a high-temperature reaction furnace for reduction, roasting and melting in sequence; the temperature of the reduction layer is 750-880°C; the temperature of the roasting layer is 1150- 1280°C, roasting time 2.0-20.0 minutes, melting layer temperature 1320-1550°C, melting time 1.0-8.0 minutes, the resulting molten slag is sprayed or centrifuged to prepare slag wool fibers; the viscosity of the molten slag is 1-3Pa· s; the mass content of the main components of the slag wool fiber is SiO ₂ 36-42%, Al ₂ O ₃ 5-12%, CaO 28-47%, MgO 1-8%, Fe ₂ O ₃ 1-5% , (K ₂ O+NaO) 0-1.2%; (4) The high-concentration SO ₂ flue gas generated by the reaction is discharged from the upper part and sent to the sulfuric acid system. The decomposition and escape rate of sulfur in phosphogypsum is 95-98%. 2. The method according to claim 1, wherein the reducing material is a C reducing agent selected from one or more of lignite, anthracite, coke, coke, and white coal. 3. The method according to claim 2, characterized in that the mixture in step (2) is crushed and passed through a 30-80 mesh sieve. 4. The method according to claim 2, characterized in that the magnesium compound is selected from one or both of boronite or blast furnace slag. 5. method according to claim 2, is characterized in that, described acidity coefficient MK is the mass ratio of contained acidic oxide and basic oxide, MK=(W _SiO2 +W _Al2O3 )/(W _CaO +W _MgO ). 6. method according to claim 2, is characterized in that, the calculating method of pH value is: pH=-0.0602W _SiO2 -0.120W _Al2O3 +0.232W _CaO +0.120W _MgO +0.144W _Fe2O3 +0.21W _Na2O .

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