CN113753864B - Method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum - Google Patents
Method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum Download PDFInfo
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- CN113753864B CN113753864B CN202111140360.8A CN202111140360A CN113753864B CN 113753864 B CN113753864 B CN 113753864B CN 202111140360 A CN202111140360 A CN 202111140360A CN 113753864 B CN113753864 B CN 113753864B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/69—Sulfur trioxide; Sulfuric acid
- C01B17/74—Preparation
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B17/00—Sulfur; Compounds thereof
- C01B17/48—Sulfur dioxide; Sulfurous acid
- C01B17/50—Preparation of sulfur dioxide
- C01B17/501—Preparation of sulfur dioxide by reduction of sulfur compounds
- C01B17/506—Preparation of sulfur dioxide by reduction of sulfur compounds of calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/04—Manufacture of glass fibres or filaments by using centrifugal force, e.g. spinning through radial orifices; Construction of the spinner cups therefor
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/06—Manufacture of glass fibres or filaments by blasting or blowing molten glass, e.g. for making staple fibres
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
- C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C13/00—Fibre or filament compositions
- C03C13/06—Mineral fibres, e.g. slag wool, mineral wool, rock wool
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
Abstract
The invention provides a method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum. According to the characteristics of phosphogypsum with high content of impurities such as silicon, aluminum, magnesium and the like, calculation and proportioning optimization are carried out, and the phosphogypsum is reduced into SO through reduction, roasting decomposition and melting 2 The byproduct molten slag obtained during the sulfuric acid preparation can be directly prepared into slag cotton fiber products with high added value through wiredrawing, blowing or centrifugation, and the S element in phosphogypsum is recycled, so that the impurity components such as high silicon, aluminum, magnesium and the like contained in the phosphogypsum are converted into raw materials for preparing the slag cotton, the raw materials such as silicon, calcium and the like required by the slag cotton can be saved, the high added value utilization of phosphogypsum cinder is realized, and the phosphogypsum acid preparation technology has higher economy and competitiveness and outstanding technical effects.
Description
Technical Field
The invention relates to the technical field of high-value utilization of phosphogypsum to prepare sulfuric acid and cinder thereof, in particular to a method for preparing sulfuric acid and co-producing slag cotton fibers from high-impurity phosphogypsum.
Background
Phosphogypsum is an industrial byproduct of wet-process phosphoric acid production, and 4.5t-5.5t of phosphogypsum is produced per 1t of phosphoric acid produced. The main component of phosphogypsum is CaSO 4 ·2H 2 O and contains a relatively small amount of SiO 2 And a small amount of MgO, al 2 O 3 、Fe 2 O 3 、P 2 O 5 Impurities such as fluoride and organic matters. At present, the phosphogypsum storage amount in China is up to about 7.5 hundred million tons, about 9000 ten thousand tons are newly increased each year, and the comprehensive utilization rate is less than 40%. The huge amount of phosphogypsum is piled up in a special slag warehouse, so that environmental protection and safety risks are brought, new phosphogypsum slag warehouses are not allowed by the state, a series of policy files are issued by related departments of the state and local governments at all levels, and higher requirements are put forward on industrial solid waste, especially on the comprehensive utilization rate of phosphogypsum, and enterprises which cannot meet the utilization rate requirements face the shutdown risks; on the other hand, a series of policy files are issued to encourage and strengthen the comprehensive utilization of a large amount of solid waste and phosphogypsum. Therefore, the comprehensive utilization problem of phosphogypsum becomes a constraint to the wet-process phosphoric acid and high-concentration phosphorus compound fertilizer in ChinaThe industry is continuously and healthily developing and the important problems need to be solved.
At present, phosphogypsum as a byproduct in the industry of wet phosphoric acid and phosphorus compound fertilizer in China is still mainly piled up in a slag warehouse, the comprehensive utilization rate, particularly the recycling utilization rate, is still at a low level, and the main utilization way is still at a primary stage of processing low-end products, such as preparing cement retarder, and is used for mine filling and processing building materials (various powder materials and sectional materials) such as building gypsum after modification. Compared with the main stream method of preparing acid by sulfur, the phosphogypsum has high production cost, a large amount of cinder can only be used as a low-end product such as cement clinker or mixed materials, and the like, has large quality fluctuation and low added value, lacks economy and competitiveness, and is difficult to apply and popularize on a large scale. Besides the maintenance of production of the individual devices due to the treatment of industrial waste, other devices for producing acid and co-producing cement from phosphogypsum are all stopped in sequence.
The mineral cotton fiber belongs to inorganic silicate fiber, is a cotton-like mineral fiber prepared by taking molten slag as a main raw material through a centrifugal/blowing method, and is a high added value product. The market selling price of the slag cotton is more than 2200 yuan/t, and the selling price of high-temperature-resistant slag cotton heat insulation board products such as partial metallurgy, chemical industry, electric power and the like is more than 10000 yuan/t. At present, slag cotton is produced by mainly utilizing solid slag such as blast furnace slag, yellow phosphorus slag and the like with the height of Wen Liantie in China through a method of hardening and tempering, homogenizing (heat preservation) and centrifugally forming the slag.
Patent CN102530886B discloses a method for preparing sulfuric acid and cement by adding sand, coke, lime, crude salt and ferrous salt into phosphogypsum, mixing, adding into a rotary kiln for calcining, decomposing to obtain SO 2 The flue gas of (2) is used for preparing sulfuric acid, and the cinder is used as cement clinker.
The phosphogypsum acid-making co-production cement is an important way for realizing mass digestion and utilization of phosphogypsum in the industry of wet phosphoric acid and phosphorus compound fertilizer, but is difficult to popularize and apply due to the large investment of devices, large occupied area, large fluctuation of clinker quality, high production cost, poor economy and the like, and becomes a great problem to be solved urgently.
Disclosure of Invention
The invention provides a method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum, aiming at the common problems of the conventional phosphogypsum for preparing sulfuric acid and coproducing cement. According to the characteristics of phosphogypsum with high content of impurities such as silicon, the calculation and the material preparation optimization are carried out, and the high-concentration SO is generated by reducing the sulfur contained in the phosphogypsum through the processes of reduction, roasting, melting and the like 2 The method is used for preparing sulfuric acid, and meanwhile, the obtained byproduct molten slag can be directly prepared into slag cotton fiber products through a blowing or centrifugal process, S element in phosphogypsum is recycled, high added value utilization of cinder is realized, meanwhile, higher silicon and partial impurity components such as aluminum and magnesium contained in phosphogypsum can be fully utilized and effectively converted into raw materials for preparing slag cotton fibers, other minerals such as silicon ore and other solid waste raw materials with higher value such as fly ash are further reduced and saved, the production cost is reduced, the influence of mineral exploitation such as silicon on the environment is reduced, so that phosphogypsum acid preparation has economic benefit and ecological environment benefit, and the method is favorable for large-scale popularization and application of phosphogypsum in the chemical industry.
Based on the purpose of the invention, the invention provides a method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum, which comprises the following steps:
(1) Adding a compound raw material containing silicon, aluminum and magnesium into 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) Crushing the mixture in the step (1), and adding a carbon-based reducing material; wherein the molar ratio of C in the carbon-based reducing material to S in phosphogypsum is 0.5-1.0:1, a step of;
(3) Adding a high-temperature-resistant binder into the material obtained in the step (2), fully and uniformly mixing, preparing and forming the material, and sending the material into a high-temperature reaction furnace to sequentially perform reduction, roasting and melting;
wherein: the temperature of the reduction layer is controlled within the range of 750-880 ℃, and the average residence time is 3.0-30.0 minutes; the temperature control range of the roasting layer is 1150-1280 ℃, the roasting time is 2.0-20.0 minutes, the temperature control range of the melting layer is 1320-1550 ℃, the melting time is 1.0-8.0 minutes, and the generated melting slag is subjected to blowing or centrifugation to prepare slag cotton fibers; the viscosity of the molten slag is 1-3 Pa.s.
(4) High concentration SO formed by the reaction 2 SO exhausted from the upper part of the furnace 2 The flue gas is sent into a sulfuric acid production system to produce acid after cyclone dust removal, waste heat recovery, washing and purification, and the decomposition escape rate of sulfur in phosphogypsum is 95-98%.
The high-impurity phosphogypsum refers to phosphogypsum with high silicon content and certain aluminum and magnesium. The high-impurity phosphogypsum is phosphogypsum containing more silicon and containing aluminum, magnesium and other impurities, and the compound raw materials of silicon, aluminum and magnesium are supplemented, so that the content of silicon, aluminum and magnesium in the phosphogypsum is further improved, and the batching requirement of slag cotton fibers prepared from the phosphogypsum is met.
The reaction principle is as follows;
reduction layer: caSO (Caso-like conductor) 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)
And (3) roasting the 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 invention, the main component of phosphogypsum is calcium sulfate, and CaO and SiO in phosphogypsum are selected from silicide, aluminide and magnesium compound 2 、Al 2 O 3 The content of MgO, the Mk is 1.1-1.5, the pH value is 4-5, and the respective proportioning amount is optimally determined.
The viscosity of the molten slag has a certain relation with the temperature, and at a higher temperature, the viscosity is smaller and the fluidity is better. When the temperature is lowered to a certain extent, the viscosity is drastically increased and the fluidity is relatively poor. The prepared slag cotton has reasonably optimized melt viscosity of 1-3 Pa.s and corresponding interval temperature of about 1270-1550 ℃, and can meet the requirements of preparing the slag cotton. When the acidity coefficient Mk of the molten slag is 1.2-1.5, the fiber diameter is smaller than 6.0 mu m, the variation range is small, and the diameter of the slag cotton slightly increases along with the increase of Mk. And the content (mass fraction) of slag balls in the slag cotton increases along with the increase of the acidity coefficient, and when the acidity coefficient increases to 1.5, the content is 5.02 percent and is within the national standard (less than or equal to 7 percent).
Preferably, the binder is added to prepare a shape of cylinder, rod, sphere, football, etc. The organic binder and the inorganic binder can be selected, the inorganic binder can be bentonite, kaolin, cement, water glass, quicklime and the like, the organic binder can be selected from coal tar, high molecular polymers (polyvinyl alcohol, phenolic resin and CMC), starch, lignocellulose and the like, and organic-inorganic compounding can be adopted when needed.
Preferably, the high concentration SO produced by the reaction in the present invention 2 The flue gas discharged from the upper part is sent into a sulfuric acid production system to produce acid after cyclone dust removal, waste heat recovery and purification, and the decomposition escape rate of sulfur in phosphogypsum is 95-98%.
Preferably, the temperature of the reduction layer of phosphogypsum is about 850 ℃, the residence time is 5 minutes, and the reaction products mainly comprise CaS and CaSO 4 And a silicon compound, etc.
Preferably, the temperature of the roasting layer is about 1220 ℃, the residence time is 5 minutes, and the reaction product mainly comprises multi-phase cinder (mainly comprising Ca, si, al, mg and the like) and SO 2 Flue gas.
Preferably, the melt layer temperature is 1450℃and the residence time is 4 minutes.
The pH value in the invention is an index for measuring the chemical stability of rock wool and slag wool accurately.
According to the method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum, 0.2-15% of sulfur powder by mass percent is added in the step (1).
The step can be replaced by spraying sulfur liquid with the same concentration into the high-temperature reaction furnace in the step (3).
The method for preparing the sulfuric acid and co-producing the slag cotton fiber by the high-impurity phosphogypsum is characterized in that the carbon-based reducing material is a carbon-based (C) reducing agent which is one or more selected from lignite, anthracite, coke butyl and white coal.
In the method for preparing acid and co-producing slag cotton fibers by using phosphogypsum, the mixture in the step (2) is crushed and then screened by a sieve with 30-80 meshes.
The method for preparing sulfuric acid and coproducing slag cotton fiber from high-impurity phosphogypsum is characterized in that silicide is one or more of silica powder, fly ash, coke ash, blast furnace slag and potassium feldspar.
The aluminide is one or more selected from fly ash, coke ash and blast furnace slag.
The method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum comprises the step of preparing magnesium compound from one or two of boron magnesium ore or blast furnace slag.
The method for preparing sulfuric acid and co-producing slag cotton fiber from high-impurity phosphogypsum comprises the following main components in percentage by mass 2 36-42％、Al 2 O 3 5-12％、CaO 28-47％，MgO 1-12％、Fe 2 O 3 1-5％、R 2 O 0-1.2％。
The method for preparing sulfuric acid and coproducing slag cotton fibers by using high-impurity phosphogypsum has the acidity coefficient Mk which is the mass ratio of the contained acidic oxide to the basic oxide,
Mk＝(W SiO2 +W Al2O3 )/(W CaO +W MgO )。
the method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum comprises the following steps of:
pH＝-0.0602W SiO2 -0.120W Al2O3 +0.232W CaO +0.120W MgO +0.144W Fe2O3 +0.21W Na2O 。
through the technical scheme, the invention provides a method for preparing sulfuric acid and coproducing slag cotton fibers from high-impurity phosphogypsum, which has the following advantages:
according to the characteristics of phosphogypsum with high silicon content and aluminum, magnesium and other impurities, calculation and material preparation optimization are carried out, and SO is generated by reducing sulfur contained in phosphogypsum through the processes of reduction, roasting, melting and the like 2 The flue gas is used for preparing sulfuric acid, and the obtained byproduct molten slag can be directly prepared by a blowing or centrifugal processThe slag cotton fiber product is prepared, and the S element in phosphogypsum is recycled, so that the high added value utilization of the cinder is realized. In addition, the high silicon contained in phosphogypsum and impurity components such as aluminum, magnesium and the like can be fully utilized, the impurities are changed into raw materials for preparing the slag cotton, other mineral resources or other solid waste raw materials with higher value are further saved, the production cost is reduced, the influence of mineral exploitation such as silicon and the like on the environment is reduced, so that the phosphogypsum acid preparation has more economic benefit and ecological environment benefit, and the phosphogypsum is favorable for large-scale popularization and application in the chemical industry field.
Drawings
The foregoing and/or additional aspects and advantages of the invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:
fig. 1 is a flow chart of a method for producing sulfuric acid from high impurity phosphogypsum and co-producing slag wool fiber as provided in example 1.
Detailed Description
The invention will be described in detail below with reference to specific embodiments and drawings for a clearer understanding of the objects, features and advantages of the technical solution, etc., but the invention may be practiced otherwise than as described in the following embodiments, it should be understood that the embodiments described herein are merely for explaining the invention and are not intended to limit the invention, and all changes made based on the derivation of the invention should be within the scope of the invention. Embodiments of the invention and features of the embodiments may be combined with each other without conflict.
Examples
As shown in fig. 1, the embodiment provides a method for preparing sulfuric acid and co-producing slag cotton fibers from high-impurity phosphogypsum, which comprises the following steps:
(1) Adding silicide, aluminide and magnesium compound into phosphogypsum with high silicon content and high impurity containing aluminum, magnesium and other impurities, controlling the acidity coefficient Mk to be 1.1-1.5 and the pH value to be 4-5; wherein the silicide is one or more selected from 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; the magnesium compound is selected from one or two of boron magnesium ore and blast furnace slag.
The acidity coefficient Mk is the mass ratio of the acidic oxide to the basic oxide in the material,
Mk＝(W SiO2 +W Al2O3 )/(W CaO +W MgO ) The method comprises the steps of carrying out a first treatment on the surface of the The method for calculating the pH value comprises the following steps:
pH＝-0.0602W SiO2 -0.120W Al2O3 +0.232W CaO +0.120W MgO +0.144W Fe2O3 +0.21W Na2O 。
(2) Crushing the mixture obtained in the step (1), sieving with a 30-80 mesh sieve, and adding a carbon-based reducing material; wherein the molar ratio of the carbon (C) in the carbon-based reducing material to the sulfur (S) in the phosphogypsum is 0.5-1.0:1, a step of; the reducing material is carbon (C) reducer selected from one or more of lignite, anthracite, coke butyl and white coal.
(3) And (3) adding a binder into the mixture obtained in the step (2) to prepare and shape, and sending the mixture into a high-temperature reaction furnace to sequentially perform reduction, roasting and melting.
Wherein: the temperature of the reduction layer is controlled to be 750-880 ℃, the residence time is controlled to be 3.0-30.0 minutes, and the main reaction principle is as follows:
and (3) reduction: caSO (Caso-like conductor) 4 +2C＝CaS+CO 2 (endothermic reaction); caSO (Caso-like conductor) 4 +4CO＝CaS+4CO 2 (endothermic reaction); caSO (Caso-like conductor) 4 +CO＝CaO+CO 2 +SO 2 (exothermic reaction);
wherein: the temperature of the roasting layer is controlled to be 1150-1280 ℃, the residence time is controlled to be 2.0-20.0 minutes, and the main reaction principle is as follows: 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)
Wherein: controlling the temperature of the melting layer to 1320-1550 ℃ and the residence time to 1.0-8.0 minutes, and obtaining slag cotton fibers by blowing or centrifuging a generated melting slag system; the viscosity of the molten slag is 1-3 Pa.s.
The main component of phosphogypsum in the invention is calcium sulfate, according to theThe silicide, aluminide and magnesium compound which need to be added are CaO, mgO, siO in phosphogypsum 2 、Al 2 O 3 The respective dosage is determined according to the content of Mk of 1.1-1.5 and pH value of 4-5. The main technical indexes of the slag cotton prepared by the invention are as follows: meets the requirements of GB/T11835-2016, and mainly examines that the average diameter of the fiber is less than or equal to 6.0 mu m, and the content of slag balls with the particle diameter of more than or equal to 0.25mm is less than or equal to 7.0 percent.
Preferably, the steps of preparing the slag cotton fiber from the molten slag through blowing or centrifugation are as follows:
the blowing experimental device mainly comprises a direct current arc furnace, a diversion trench and a high-speed airflow spray gun. Arc striking is carried out on the arc furnace by adopting a graphite electrode, and the smelting capacity is 100kg/h; the nozzle adopts a Raoult tube design, and the highest wind pressure is 0.45MPa. The molten slag is smelted by an electric arc furnace and then is conveyed to a high-speed airflow gun nozzle through a diversion trench, and fibers formed by blowing are collected under the action of a cotton collecting system. Blown fiberization is a process in which a continuous blast furnace slag melt is broken up into fibers by high velocity gas streams.
Centrifuging to prepare slag cotton fibers: the molten slag is dropped into a centrifuge through a diversion trench to prepare fibers, and the fibers are further processed into boards through the subsequent procedures of sizing, cotton collecting, board forming, solidification treatment and the like. The slag cotton product prepared by directly fiberizing the molten slag on line is prepared by directly throwing out fibers from blast furnace slag through a four-roller centrifugal machine rotating at high speed, then spraying a proper amount of adhesive, and then performing the working procedures of forming, drying, solidifying and the like. The fiber forming device mainly comprises a direct current arc furnace, a diversion trench, a four-roller centrifuge and the like.
The diameters of four rollers of the four-roller centrifugal machine are 213mm, 295mm and 295mm respectively, and the rotating speeds of the four rollers during the test are respectively as follows: 2707. 3093, 4350, 5800r/min. Or the diameters of four rollers of the four-roller centrifugal machine are respectively 1#213mm, 2#295mm, 3#295mm and 4#295mm, and the rotation speeds of the four rollers are respectively as follows in the experiment: 1#2070-3000r/min, 2#3093-4000r/min, 3#4350-4500r/min, 4#5000-5800r/min. The molten slag is conveyed to a centrifugal machine through a diversion trench as in the blowing method, and the formed slag cotton enters a settling chamber under the action of a fiber-forming blower and a cotton collecting induced draft fan. The mass percentage of the main components of the obtained slag cotton 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 O0-1.2% and other components.
(4) High concentration SO formed by the reaction 2 And the flue gas is discharged from the upper part and is sent to an acid making device for acid making, and the escape rate of sulfur in phosphogypsum is 95-98%.
Example 1
The compositions of the raw materials used in this example and the following examples are shown in Table 1.
Table 1 composition of raw materials used in examples (mass percent)
100 parts by mass of phosphogypsum, 18.5 parts by mass of fly ash, 8 parts by mass of iron tailings and 10 parts by mass of silica are crushed and sieved by a 40-mesh sieve, 7.2 parts by mass of coke (with a fixed carbon content of 63.62%) is added according to the molar ratio of 0.8 of sulfur (S) in the carbon (C) and the phosphogypsum, and the acidity index MK=1.32 and the pH=4.40 of the ingredients meet the batching requirements of slag rock wool. All the raw materials are uniformly mixed, added with a binder to prepare a bar-shaped section, and sent into a high-temperature reaction furnace to be reduced, roasted and melted in sequence; controlling the temperature of a reduction layer to 850 ℃, the average retention time of materials to 10.0 minutes, the temperature of a roasting layer to 1220 ℃, the average retention time of materials to 5.0 minutes, the temperature of a melting layer to 1450 ℃, and the average retention time of materials to 4.0 minutes, wherein the generated molten slag is sprayed and blown to prepare slag cotton fibers; the viscosity of the molten slag was 1.8 Pa.s. The escape rate of sulfur in phosphogypsum is 97%, and SO in the flue gas generated by the reaction 2 The mass fraction of the slag is 7.5%, the flue gas is discharged from the upper part, is sent to a sulfuric acid production system for producing acid after dust removal, waste heat recovery and washing purification, and the molten slag is discharged from the lower part, so that the slag cotton is prepared through a blowing process. The prepared slag cotton comprises the following components: caO 29.60%, siO 2 34.91％、Al 2 O 3 5.89％、MgO 1.37％、Fe 2 O 3 1.0％、Na 2 O0.19%, water content 0.73%, fiber diameter 4.8 μm, slag ball content 0.73%.
Example 2
100 parts by mass of phosphogypsum, 22.5 parts by mass of fly ash and 25 parts by mass of iron tailings are crushed and pass through a 40-mesh sieve, 8.0 parts by mass of coke (fixed carbon content 65.1%) is added according to the molar ratio of 0.9 of carbon (C) to sulfur (S) in the phosphogypsum, and the acidity index MK=1.46 and the pH value=4.29 of the ingredients meet the batching requirements of slag rock wool. All the raw materials are uniformly mixed, added with a binder to prepare a bar-shaped section, and sent into a high-temperature reaction furnace to be reduced, roasted, oxidized and melted in sequence; wherein: controlling the temperature of a reduction layer to 830 ℃, the average retention time of materials to 15.0 minutes, the temperature of a roasting layer to 1200 ℃, the average retention time of materials to 10.0 minutes, the temperature of a melting layer to 1400 ℃ and the average retention time of materials to 6.0 minutes, and preparing slag cotton fibers by spraying and blowing generated molten slag; the viscosity of the molten slag was 2.1 Pa.s. The escape rate of sulfur in phosphogypsum is 95%, and SO in the flue gas generated by the reaction 2 The mass fraction of the slag is 7.2%, the flue gas is discharged from the upper part, is sent to a sulfuric acid production system for producing acid after dust removal, waste heat recovery and washing purification, and the molten slag is discharged from the lower part, so that the slag cotton is prepared through a blowing process. The prepared slag cotton comprises the following components: caO 30.14%, siO 2 39.87％、Al 2 O 3 7.44％、MgO 2.24％、Fe 2 O 3 1.77％、Na 2 O0.34%, water content 0.61%, fiber diameter 4.2 μm, slag ball content 3.18%.
Example 3
100 parts by mass of phosphogypsum, 17 parts by mass of fly ash, 10 parts by mass of iron tailings and 15 parts by mass of silica are crushed and sieved by a 40-mesh sieve, 7.2 parts by mass of coke (with a fixed carbon content of 68.21%) is added according to the molar ratio of 0.85 of carbon (C) to sulfur (S) in phosphogypsum, and the acidity index MK=1.47 and the pH=4.15 of the mixture meet the mixture requirement of slag rock wool. All the raw materials are uniformly mixed, added with a binder to prepare a bar-shaped section, and sent into a high-temperature reaction furnace to be reduced, roasted and melted in sequence; wherein: the temperature of the reduction layer is controlled to 780 ℃, the average retention time of materials is 18.0 minutes, the temperature of the roasting layer is 1250 ℃, the average retention time of materials is 4.0 minutes, the temperature of the melting layer is 1550 ℃, the average retention time of materials is 3.0 minutes,producing molten slag, and preparing slag cotton fibers through spray blowing; the viscosity of the molten slag was 2.3 Pa.s. The escape rate of sulfur in phosphogypsum is 96%, and SO in the flue gas generated by the reaction 2 The mass fraction of the slag is 7.8%, the flue gas is discharged from the upper part, and is sent to a sulfuric acid making system for making acid after dust removal, waste heat recovery, washing and purification, and is sent to the acid making system, the molten slag is discharged from the lower part, and the slag cotton is prepared through a blowing process. The prepared slag cotton comprises the following components: caO 29.67%, siO 2 40.08％、Al 2 O 3 5.70％、MgO 1.38％、Fe 2 O 3 1.09％、Na 2 O0.22%, water content 2%, fiber diameter 5.8 μm, slag ball content 4.21%.
Example 4
Adding 5% of sulfur powder into the step (1), and reacting to generate SO in the flue gas 2 The mass fraction of the slag is 9%, the flue gas is discharged from the upper part, is sent to a sulfuric acid production system for producing acid after dust removal, waste heat recovery and washing purification, and the molten slag is discharged from the lower part, so that the slag cotton is prepared through a blowing process. Other technical features of this embodiment are the same as those of embodiment 1, and are not described in detail here.
Comparative example 1
100 parts by mass of phosphogypsum, 15 parts by mass of fly ash and 5 parts by mass of iron tailings are crushed and pass through a 40-mesh sieve, 7.2 parts by mass of coke (fixed carbon content is 63.62%) is added according to the molar ratio of carbon (C) to sulfur (S) in the phosphogypsum of 0.8, and the acidity index MK=0.9 and the pH value=5.1 of the mixture. All the raw materials are uniformly mixed, added with a binder to prepare a bar-shaped section, and sent into a high-temperature reaction furnace to be reduced, roasted and melted in sequence; the temperature of the reduction layer is controlled to 850 ℃, the average retention time of materials is controlled to 10.0 minutes, the temperature of the roasting layer is controlled to 1220 ℃, the average retention time of materials is controlled to 5.0 minutes, the temperature of the melting layer is controlled to 1450 ℃, the average retention time of materials is controlled to 4.0 minutes, and the viscosity of molten slag is controlled to 1.8 Pa.s. The escape rate of sulfur in phosphogypsum is 97%, and SO in the flue gas generated by the reaction 2 The mass fraction of the slag is 7.5%, the flue gas is discharged from the upper part, and is sent to a sulfuric acid production system for producing acid after dust removal, waste heat recovery and washing purification, the molten slag is discharged from the lower part, and the slag comprises the following components: caO 29.07%, siO 2 22.69％、Al 2 O 3 4.45％、MgO 1.02％、Fe 2 O 3 0.67％、Na 2 O0.14%, a good vitreous structure cannot be formed, and slag wool cannot be prepared.
Comparative example 2
100 parts by mass of phosphogypsum, 22.5 parts by mass of fly ash and 35 parts by mass of iron tailings are crushed and pass through a 40-mesh sieve, 7.2 parts by mass of coke (fixed carbon content is 63.62%) is added according to the molar ratio of carbon (C) to sulfur (S) in the phosphogypsum of 0.8, and the acidity index MK=1.66 and the pH value=4.01 of the mixture. All the raw materials are uniformly mixed, added with a binder to prepare a bar-shaped section, and sent into a high-temperature reaction furnace to be reduced, roasted and melted in sequence; the temperature of the reduction layer is controlled to 850 ℃, the average retention time of materials is controlled to 10.0 minutes, the temperature of the roasting layer is controlled to 1220 ℃, the average retention time of materials is controlled to 5.0 minutes, the temperature of the melting layer is controlled to 1450 ℃, the average retention time of materials is controlled to 4.0 minutes, and the viscosity of molten slag is controlled to 3.1 Pa.s. The escape rate of sulfur in phosphogypsum is 97%, and SO in the flue gas generated by the reaction 2 The mass fraction of the slag is 7.5%, the flue gas is discharged from the upper part, is sent to a sulfuric acid production system for producing acid after dust removal, waste heat recovery and washing purification, and the molten slag is discharged from the lower part, so that the slag cotton is prepared through a blowing process. The prepared slag cotton comprises the following components: 30.44% CaO and SiO 2 47.07％、Al 2 O 3 7.93％、MgO 2.65％、Fe 2 O 3 2.25％、Na 2 O0.43%, water content 2.5%, fiber diameter 8.2 μm, slag ball content 4.21%, and can not meet the index requirements of slag cotton products.
The above is only an example of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, improvement, equivalent replacement, etc. made within the inventive and innovative principles of this invention should be considered to be within the scope of the invention.
Claims (6)
1. The method for preparing the sulfuric acid and coproducing the slag cotton fiber from the high-impurity phosphogypsum is characterized by at least comprising the following steps:
(1) Adding silicon, aluminum and magnesium-containing compounds into high-impurity phosphogypsum, controlling the acidity coefficient MK to be 1.1-1.5 and the pH value to be 4-5; and 0.2 to 15 mass percent of sulfur powder is added; the silicide is one or more selected from 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) Crushing the mixture in the step (1), and adding a carbon-based reducing material; wherein the mole ratio of C in the reducing material to S in phosphogypsum is 0.5-1.0:1, a step of;
(3) Adding a high-temperature-resistant binder into the material obtained in the step (2) for molding, and sending the material into a high-temperature reaction furnace for sequentially carrying out reduction, roasting and melting; wherein the temperature of the reduction layer is 750-880 ℃; the temperature of the roasting layer is 1150-1280 ℃, the roasting time is 2.0-20.0 minutes, the temperature of the melting layer is 1320-1550 ℃, the melting time is 1.0-8.0 minutes, and the produced melting slag is subjected to blowing or centrifugation to prepare slag cotton fibers; the viscosity of the molten slag is 1-3 Pa.s; the mass content of the main component of the slag cotton 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) High concentration SO formed by the reaction 2 The flue gas is discharged from the upper part and is sent into a sulfuric acid preparation system, and the decomposition 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 breeze, white coal.
3. The method of claim 2, wherein the mixture in step (2) is crushed and passed through a 30-80 mesh screen.
4. The method according to claim 2, wherein the magnesium compound is selected from one or both of a boron magnesium ore or a blast furnace slag.
5. The method according to claim 2, characterized in that the acidity coefficient MK is the mass ratio of the acidic oxide and the basic oxide contained, mk= (W) SiO2 +W Al2O3 )/(W CaO +W MgO )。
6. The method according to claim 2, wherein the pH is calculated by:
pH=-0.0602W SiO2 -0.120W Al2O3 +0.232W CaO +0.120W MgO +0.144W Fe2O3 +0.21W Na2O 。
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