Disclosure of Invention
The invention aims to provide a method for producing phosphogypsum by utilizing a wet-process phosphoric acid process at a low-carbon interface, which aims to produce phosphogypsum for agriculture and phosphogypsum for construction by utilizing the wet-process phosphoric acid process and improve the economic value of phosphogypsum.
The invention is realized in the following way:
In a first aspect, the invention provides a method for producing phosphogypsum by using a wet phosphoric acid process at a low carbon interface, comprising the following steps: mixing phosphorite and inorganic acid, performing extraction and crystal growth to obtain extraction slurry, performing super-aeration flotation on the extraction slurry, introducing super-aeration microbubbles into the extraction slurry through super-aeration flotation, grading to obtain an air flotation layer and a floating residue layer, performing solid-liquid separation on the air flotation layer to obtain phosphogypsum for agriculture, and performing solid-liquid separation on the floating residue layer to obtain phosphogypsum for construction;
Wherein the ultra-aeration micro-bubble contains a surfactant.
In an alternative embodiment, the ultra-aeration microbubbles are introduced in the form of a gas-liquid mixed phase, the gas is introduced into the liquid phase with pressure to form the gas-liquid mixed phase, and the gas-liquid mixed phase is introduced into the extraction slurry through an aeration disc;
Preferably, the pressure of the gas-liquid mixed phase is 0.1MPa-1.0MPa, the gas phase comprises microbubbles with the diameter of 0.1-50 μm, and the gas phase accounts for 1-30wt% of the gas-liquid mixed phase;
Preferably, the mass ratio of the gas-liquid mixed phase to the slurry to be treated is (5-30): 100.
In an alternative embodiment, the surfactant is added to the liquid phase in an amount of 1.0mg/L to 4.0mg/L;
Preferably, the surfactant is at least one selected from anionic surfactants, cationic surfactants, zwitterionic surfactants, nonionic surfactants and natural surfactants of unknown nature; wherein the anionic surfactant comprises carboxylate, sulfate and sulfonate; nonionic surfactants include esters and ethers;
more preferably, the surfactant is at least one selected from cetyltrimethylammonium bromide, polydimethyldiallylammonium chloride and quaternary chitosan.
In an alternative embodiment, an extractant is also added into the liquid phase, and the addition amount of the extractant is 1mg/L to 20mg/L;
Preferably, the extractant is selected from at least one of fatty alcohols, ethers, ketones, esters and phosphates;
more preferably, the extractant is selected from at least one of n-butanol, isobutanol, isoamyl alcohol, isopropyl ether, isobutyl ether, methyl isobutyl ketone, propyl acetate, butyl acetate and tributyl phosphate.
In an alternative embodiment, the extraction slurry is sequentially subjected to multistage super-aeration flotation, wherein each stage of super-aeration flotation is to introduce super-aeration microbubbles into the extraction slurry, and the extraction slurry enters a classification channel for classification after the multistage super-aeration flotation;
Preferably, in the multistage super-aeration floating process, the time for treating the extraction slurry in the super-aeration micro-bubbles is controlled to be 1-15 min;
Preferably, classification is performed in a classification channel by using a dynamic settler, and air-float layer slurry is output above the dynamic settler, and surplus layer slurry is output below the dynamic settler.
In an optional embodiment, the super aeration floating device for performing multi-stage super aeration floating comprises an outer shell, wherein a sleeve structure is arranged in the outer shell, the sleeve structure is formed by sequentially sleeving a plurality of pipelines, communication holes are formed between two adjacent pipelines, aeration structures are arranged between the two adjacent pipelines, each aeration structure comprises a connecting pipe and a plurality of aeration discs, the plurality of aeration discs are distributed on the connecting pipe at intervals, and each connecting pipe is connected with an external aeration generator;
The bottom of the super-aeration air flotation device is provided with a feed inlet, a grading channel is formed between the outermost layer pipeline in the sleeve structure and the outer shell, the top side wall of the grading channel is provided with an air flotation layer discharge outlet, and the bottom of the grading channel is provided with a floating residue layer discharge outlet;
Preferably, the sleeve structure is formed by sequentially sleeving an inner pipeline, a middle pipeline and an outermost pipeline, wherein a plurality of first communication holes are distributed on the pipe wall of the inner pipeline; a plurality of second communication holes are distributed on the pipe wall of the middle pipeline; a primary aeration structure is arranged in the inner pipeline, a secondary aeration structure is arranged between the inner pipeline and the middle pipeline, a tertiary aeration structure is arranged between the middle pipeline and the outermost pipeline, and the mounting heights of the primary aeration structure, the secondary aeration structure and the tertiary aeration structure are gradually increased;
The first communication holes are distributed from the top to the bottom of the inner layer pipeline, and the second communication holes are distributed in the area of the middle pipeline above the secondary aeration structure; a first dynamic settler is arranged at the top of the outermost pipeline;
the top of the outermost pipeline is arranged at intervals with the top of the outer shell so as to form an overflow port overflowed from the outermost pipeline to the classification channel; the classification channel is provided with a second dynamic settler, and the discharge port of the air flotation layer is positioned above the second dynamic settler.
In an alternative embodiment, the liquid phase is at least one of system slurry, wash water, and return acid.
In an alternative embodiment, the ultra-aeration micro-bubbles are introduced in at least one of the extraction stage and the seeding stage.
In an alternative embodiment, flash evaporation is carried out after crystal growth by extraction, and then super aeration floatation is carried out; and introducing ultra-aeration micro-bubbles in at least one of the extraction stage, the crystal growing stage and the flash evaporation stage.
In an alternative embodiment, the mineral acid is selected from at least one of sulfuric acid, nitric acid, and hydrochloric acid;
preferably, phosphorite and inorganic acid aqueous solution are mixed for extraction and crystal growth, the concentration of SO 3 in the inorganic acid aqueous solution is 0.03g/mL-0.05g/mL, and the liquid-solid mass ratio is controlled to be 1.5-3.0.
The invention has the following beneficial effects: the method comprises the steps of introducing ultra-aeration micro-bubbles containing surfactant into extraction slurry obtained by a wet phosphoric acid process, gradually reducing the pressure of the slurry in the process of floating the bubbles, so that the internal pressure and the external pressure of the ultra-aeration micro-bubbles are gradually unbalanced, the ultra-aeration micro-bubbles can be broken to generate smaller bubbles, the surfactant can be used for enhancing the adhesion of impurities, thereby taking away the impurities, finally, the slurry is in a slurry distribution state of an upper air flotation layer and a lower floating residual layer, the slurry of the upper air flotation layer and the slurry of the lower floating residual layer are graded and subjected to solid-liquid separation, a filter cake obtained by filtering the floating residual layer accords with the relevant standard of building materials, the attribute of phosphogypsum building materials is greatly improved, and the filter cake obtained by filtering the air flotation layer accords with the relevant standard of phosphogypsum for agriculture after blocking heavy metal mobility to soil by a chemical curing method. The invention utilizes the ultra-aeration micro-bubbles containing the surfactant to carry out the ultra-aeration flotation on the extraction slurry, so that phosphogypsum produced by the process can be directly used as raw materials, thereby reducing the fund and energy consumption of solid waste treatment and improving the economic value of phosphogypsum.
The low-carbon interface in the invention realizes the prepositive separation of harmful components influencing the use value of phosphogypsum in the traditional phosphoric acid extraction process, achieves the aims of low energy consumption, low pollution and low emission in the interface of the whole production process and the aim of graded comprehensive utilization of phosphogypsum, and realizes the comprehensive benefits of energy conservation, emission reduction, environmental protection and solid waste resource utilization. The embodiment of the invention provides the simultaneous production of the phosphogypsum for agriculture and the phosphogypsum for construction on the basis of the wet phosphoric acid process for the first time.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the prior art, the phosphogypsum as solid waste is firstly mixed with components harmful to the phosphogypsum building property due to the process reasons, and a large amount of water resources and energy are consumed in the later period to separate out the harmful components, so that the utilization value of the phosphogypsum as a high-quality resource of the building material is severely restricted. However, the components (organic matters, phosphorus, fluorine and sesquioxide) affecting the building properties of phosphogypsum are treated by super-exposure classification air floatation and are high-quality raw materials for producing high-quality organic fertilizer with soil improvement.
Therefore, the embodiment of the invention utilizes the ultra-aeration micro-bubbles containing the surfactant to carry out the ultra-aeration flotation on the extraction slurry on the basis of the prior art, thereby realizing the prepositive separation of impurities according to the useful value thereof in the phosphogypsum production process, improving the effective utilization rate of phosphorus, realizing the multipurpose use value of phosphogypsum, reducing the carbon consumption in the phosphogypsum formation process and the recycling process, obtaining the high-quality agricultural base material for soil improvement and the high-quality base material for construction and transportation industry, fundamentally avoiding the problems of waste and accumulation in the phosphoric acid production process and the solid waste phosphogypsum formation process, and realizing the low-carbon interface of the phosphoric acid production process and the phosphogypsum recycling.
The method for producing phosphogypsum by utilizing wet-process phosphoric acid at a low-carbon interface in the embodiment of the invention, please refer to fig. 2, comprises the following steps:
S1, extracting and growing crystals
Mixing phosphorite and inorganic acid for extraction and crystal growth to obtain extraction slurry, the process of extracting and crystal growth can refer to the prior process, mixing phosphorite and inorganic acid for extraction and crystal growth, the extraction and crystal growth can be respectively carried out in two tanks, and the slurry after extraction can overflow to a crystal growth tank for crystal growth.
In some embodiments, the inorganic acid is selected from at least one of sulfuric acid, nitric acid and hydrochloric acid, and may be any one or more of the above. The inorganic acid and water are mixed and dissolved to obtain an inorganic acid aqueous solution, the phosphorite and the inorganic acid aqueous solution are mixed for extraction and crystal growth, the concentration of SO 3 in the inorganic acid aqueous solution is 0.03g/mL-0.05g/mL, the liquid-solid mass ratio is controlled to be 1.5-3.0, and the extraction effect is further improved by regulating and controlling the dosage ratio of the phosphorite and the inorganic acid aqueous solution. Specifically, the concentration of SO 3 in the inorganic acid aqueous solution can be 0.03g/mL, 0.04g/mL, 0.05g/mL, etc., and the liquid-solid mass ratio can be 1.5:1, 2.0:1, 2.5:1, 3.0:1, etc.
In some embodiments, at least one of the extraction stage and the crystal growing stage is filled with ultra-aeration microbubbles generated by a high-pressure aeration device, and an aeration disc is added in the existing extraction and/or crystal growing device, wherein the aeration disc can be an existing aeration device, such as available from Shengtai environmental protection filler Co. The formation of the ultra-aeration microbubbles can be described with reference to the content of S3.
In the extraction reaction, a great amount of heat is released in the extraction, so that the process of enhancing crystallization conditions by introducing a great deal of heat transfer and vortex mixing in the original extraction and crystal growth stirring tank is greatly facilitated, the process conditions of phosphoric acid extraction and phosphogypsum grain growth are greatly optimized, the yield of phosphorus and the phosphogypsum filtration strength are improved, high-quality phosphogypsum is obtained, and further, the filtration energy consumption is lower. Meanwhile, the super exposure also enables the slurry to be layered, so that the phosphogypsum classification application is realized; the forced gas-liquid microcirculation stirring system is added, the reaction condition is optimized, the quality of the product and the use value of byproducts are greatly improved, and a low-carbon interface, high efficiency and energy conservation in the production process are realized. In addition, after the bubbles burst, an emulsion layer is generated at the gas-liquid-solid interface, substances with high viscosity such as organic matters, aluminum and the like can float on the emulsion layer, the residual phosphorus can be divided into an air floatation layer and a floating residual layer, the air floatation layer can be filtered, impurity components (such as organic matters, fluorides, iron aluminum and the like) are mainly concentrated on the air floatation layer, and the impurities are useful for phosphogypsum for agriculture and are suitable for further preparing agricultural fertilizers.
S2, flash evaporation
The flash evaporation can reduce the temperature of the slurry, is not an essential step in the wet phosphoric acid process, and the method provided by the embodiment of the invention is improved on the existing device, and if the existing process is provided with a flash evaporation stage, the flash evaporation stage is reserved.
In some embodiments, the ultra-aeration micro-bubbles generated by the high-pressure aeration device are introduced in at least one of the extraction stage, the crystal growing stage and the flash evaporation stage, and the ultra-aeration micro-bubbles generated by the high-pressure aeration device are introduced in at least one of the extraction stage, the crystal growing stage and the flash evaporation stage, so that the impurity removal effect is improved, the impurities are concentrated on the upper layer more, the flash evaporation energy can be reduced, and the flash evaporation effect is improved. The formation of the ultra-aeration microbubbles can be described with reference to the content of S3.
S3, super aeration floating and grading
The extraction slurry is subjected to super aeration flotation, wherein the extraction slurry refers to the slurry obtained in the step S1, and the wet phosphoric acid process with a flash evaporation stage refers to the slurry obtained in the step S2. The extracted slurry is subjected to super-aeration flotation and classification to obtain an air flotation layer and a floating residual layer, the air flotation layer is subjected to solid-liquid separation to obtain phosphogypsum for agriculture, and the floating residual layer is subjected to solid-liquid separation to obtain phosphogypsum for construction, as shown in figure 3. The phosphogypsum for agriculture and the phosphogypsum for construction can be respectively washed and dried and stored in the phosphogypsum storage tank for agriculture and the phosphogypsum storage tank for construction.
Specifically, super aeration is carried out to extract slurry, super aeration micro bubbles containing surfactant are introduced, in the process of floating up the bubbles, the pressure of the slurry is gradually reduced, so that the pressure inside and outside the super aeration micro bubbles is gradually unbalanced, the super aeration micro bubbles can be broken to generate smaller bubbles, the surfactant can be used for enhancing the adhesion of impurities, thereby taking away the impurities, finally, the slurry is in a slurry distribution state of an upper air flotation layer and a lower floating residual layer, the slurry of the upper air flotation layer and the lower floating residual layer is graded and subjected to solid-liquid separation, a filter cake obtained by filtering the floating residual layer accords with the relevant standard of building materials, the property of phosphogypsum building materials is greatly improved, and the filter cake obtained by filtering the air flotation layer accords with the relevant standard of agricultural phosphogypsum after blocking heavy metal mobility to soil by a chemical curing method.
Further, the ultra-aeration micro-bubbles are introduced in the form of a gas-liquid mixed phase, the gas-liquid mixed phase is formed by pressurizing the gas introduced into the liquid phase, and the gas-liquid mixed phase is introduced into the extraction slurry through an aeration disc. The pressure of the gas-liquid mixed phase is 0.1MPa-1.0MPa, the gas phase comprises microbubbles with the diameter of 0.1 mu m-50 mu m, the gas phase accounts for 1wt% -30wt% of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is (5-30): 100. the specific operation parameters of the ultra-aeration micro-bubbles are optimized to improve the impurity removal effect, so that the purity of the phosphogypsum product is further improved, and the purity requirement of the phosphogypsum of the building class is met.
Specifically, the pressure of the gas-liquid mixed phase may be 0.1MPa, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, etc. The gas phase may be composed of microbubbles having diameters of 0.1 μm to 50. Mu.m, specifically 0.1 μm, 0.5 μm, 1.0 μm, 3.0 μm, 5.0 μm, 10.0 μm, 20.0 μm, 30.0 μm, 40.0 μm, 50.0 μm, etc. The proportion of the gas phase to the gas-liquid mixed phase can be 1wt%, 3wt%, 5wt%, 8wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, etc. The mass ratio of the gas-liquid mixed phase to the extraction slurry may be 5:100, 10:100, 15:100, 20:100, 25:100, 30:100, etc.
In some embodiments, the liquid phase is at least one of a system slurry, wash water, and return acid, the system slurry being an extraction slurry in a wet-process phosphoric acid system; the washing water is washing water obtained by washing the solid after filtering the floating layer; the acid return refers to dilute phosphoric acid obtained after filtration of an air floatation layer and a surplus layer.
In some embodiments, the surfactant may be added to the liquid phase in an amount of 1.0mg/L to 4.0mg/L. The adhesive effect of the impurities can be enhanced by adding the surfactant, so that the impurities are taken away, and finally the slurry is in a slurry distribution state of an upper air flotation layer and a lower floating residual layer, and the slurries of the upper air flotation layer and the lower floating residual layer are separated and filtered respectively. The inventor finds that the filter liquor obtained by filtering the air flotation layer and the floating residual layer are phosphoric acid products with better quality, the filter cake obtained by filtering the floating residual layer accords with the related standard of building materials, so that the property of phosphogypsum building materials is greatly improved, and the filter cake obtained by filtering the air flotation layer accords with the related standard of agricultural phosphogypsum after blocking the mobility of heavy metals to soil by a chemical curing method.
Further, the surfactant is at least one selected from anionic surfactant, cationic surfactant, zwitterionic surfactant, nonionic surfactant and natural surfactant with unknown property, and can be any one or more of the above surfactants. The natural surfactant with unknown properties is a natural surfactant which is not anionic, cationic, zwitterionic or nonionic.
Anionic surfactants are those in which the surface-active ions generated upon dissociation in aqueous solution are negatively charged and generally consist of an ionic hydrophilic group and an oil-soluble lipophilic group. The specific classification is as follows: (1) carboxylates. Such as alkali metal soap, and has a molecular structure of R-COONa (K). It is made up by using animal and vegetable oil and sodium hydroxide (potassium) through the process of saponification. Soap surfactants are not hard water resistant and most contain free base and therefore are not suitable for use with alkaline earth containing pesticides such as bordeaux mixture to avoid calcium soap formation and loss of surface activity in water. (2) sulfate salts. The molecular structure is expressed as R-OSO 3 Na, and is the sulfated product of fatty alcohol. Such as turkish red oil obtained by reacting castor oil with concentrated sulfuric acid at a lower temperature and neutralizing with sodium hydroxide. (3) sulfonates. The molecular structural formula is R-SO 3 Na (Ca), and R is alkylaryl. This is currently the most important and common class of surfactants. The composite emulsifier has quite strong resistance to hard water and acid and alkali, wide application and various varieties, wherein sodium dodecyl benzene sulfonate and alkyl naphthalene sulfonate such as nekal are wetting agents commonly used in wettable powder, and calcium dodecyl benzene sulfonate is an important component of the existing composite emulsifier.
Cationic surfactants are capable of generating hydrophobic cations, such as quaternary ammonium ions, in water, mostly nitrogen-containing organic compounds, and rarely phosphorous-or sulfur-containing organic compounds. Mainly quaternary ammonium compounds. Such as cetyl trimethyl quaternary ammonium bromide and stearyl dimethyl benzyl quaternary ammonium chloride.
The amphoteric surfactant is a cationic surfactant or an anionic surfactant, which has both positive and negative charge groups in the molecule, depending on the pH value of the medium. The amphoteric surfactant can be natural products and artificial products, and lecithin is common in natural products; in the synthetic amphoteric surfactant, the cationic part is ammonium salt or quaternary ammonium salt, and the anionic part is mainly carboxylate, sulfate, sulfonate and the like.
The nonionic surfactant is not dissociated in water, has stable property, is resistant to hard water, has good emulsifying, wetting, dispersing and dissolving assisting performances, and is a main emulsifier for processing pesticides. The chemical structure of the main species is divided into two categories of esters and ethers. (1) esters. For example, polyoxyethylene fatty acid esters, the molecular structure of which is represented by RCOO (CH 2CH2O)n H. The fatty acid moiety is an oleophilic moiety, most of which is lauric acid, oleic acid, stearic acid or ricinoleic acid.
In a preferred embodiment, the surfactant is at least one selected from cetyltrimethylammonium bromide, polydimethyldiallylammonium chloride and quaternary ammonium chitosan, and may be any one or more of the above. The above surfactants can further improve the impurity removal effect, and the raw materials are easy to obtain.
In some embodiments, an extractant may be further added to the liquid phase, and the addition amount of the extractant is 1mg/L to 20mg/L (such as 1mg/L, 5mg/L, 10mg/L, 15mg/L, 20mg/L, etc.), and the removal effect of impurities can be further improved by further introducing the extractant. The extractant is at least one selected from fatty alcohols, ethers, ketones, esters and phosphates, and can be any one or more of the above.
Specifically, fatty alcohols are the most used solvents for various research institutions, such as n-butanol, isobutanol, isoamyl alcohol, etc. The aliphatic alcohol solvent has low price, can be repeatedly used, has very little toxicity and corrosiveness, has poor purifying effect on anions, is easy to be mutually dissolved with water, has high recovery cost in the later period, and is not thorough for purifying high-concentration phosphoric acid.
The ethers are usually isopropyl ether and isobutyl ether, which hardly extract phosphoric acid with low concentration, but have outstanding extraction effect on phosphoric acid with high concentration, and have better selectivity on metal ions and sulfate ions, but have poorer purification effect on anions, are improper to store, are easy to cause fire and cause explosion, and threaten personal safety.
The most commonly used ketones and esters are methyl isobutyl ketone (MIBK), and in addition to propyl acetate, butyl acetate, and the like. The advantages and disadvantages are similar to ethers.
The phosphate is mainly tributyl phosphate (TBP), the TBP is insoluble in water, and after extraction, phosphate radical, fluorine and metal impurities contained in an extraction phase are less, but the TBP has high price, high density and viscosity and difficult layering. TBP is often used with a small amount of diluent added to reduce viscosity to accelerate phase separation, and is easier to recycle.
Similar to the method for purifying wet phosphoric acid, each extractant has different optimal application ranges for purifying phosphoric acid, and the extraction effect of the composite extractant is much better than that of a single type of extractant for crude phosphoric acid, and how to select the extractant mainly refers to objective conditions such as the impurity types, the impurity numbers, the concentration of the crude phosphoric acid and the like in the phosphoric acid.
In a preferred embodiment, the extractant is at least one selected from n-butanol, isobutanol, isoamyl alcohol, isopropyl ether, isobutyl ether, methyl isobutyl ketone, propyl acetate, butyl acetate and tributyl phosphate, and can be any one or more of the above, and the above extractants have easily available raw materials and better impurity removal effect.
In some embodiments, the extraction slurry is sequentially subjected to multi-stage super-aeration flotation, wherein each stage of super-aeration flotation is to introduce super-aeration micro-bubbles into the extraction slurry, and the extraction slurry enters a classification channel for classification after multi-stage super-aeration flotation, so that air-flotation layer slurry and floating residue layer slurry are obtained after classification, and the air-flotation layer slurry and the floating residue layer slurry are filtered respectively. In the multistage super aeration floating process, the treatment time of the extraction slurry in the super aeration micro-bubbles is controlled to be 1min-15min (such as 1min, 3min, 5min, 8min, 10min, 13min, 15min and the like), and the quality of phosphogypsum is improved by optimizing the treatment time so that impurities are more fully removed.
In some embodiments, classification may be performed in a classification tunnel using a dynamic settler, with the air bed slurry being output above the dynamic settler and the retentate bed slurry being output below the dynamic settler, but is not limited to classification using a dynamic settler.
The process of super-aeration flotation and classification can be operated by using the first super-aeration flotation device 100 shown in fig. 4 to 6, and the specific structure is as follows:
Referring to fig. 4, the first super-aeration air-floating device 100 includes an outer housing 110, a sleeve structure is disposed in the outer housing 110, the sleeve structure is formed by sequentially sleeving a plurality of pipelines, and communication holes are disposed between two adjacent pipelines, so that materials in an inner pipeline can enter an outer pipeline. An aeration structure 130 is arranged between two adjacent pipelines, the aeration structure 130 is obtained according to the number of the pipelines in the sleeve structure, and the specific number is not limited.
Further, a feed port 001 is provided at the bottom of the first super aeration air floatation device 100, a classification channel 002 is formed between the outermost layer pipeline 121 in the sleeve structure and the outer shell 110, an air floatation layer discharge port 003 is provided at the top side wall of the classification channel 002, and a floating layer discharge port 004 is provided at the bottom of the classification channel 002. The extraction slurry enters the sleeve structure from the feed inlet 001, is subjected to aeration treatment by the plurality of aeration structures 130, so that impurities float upwards along with bubbles, and are finally classified in the classification channel 002, the slurry with relatively more impurities is output from the air floatation layer discharge port 003 at the top, and the slurry with less impurities is output from the floating residual layer discharge port 004 at the bottom.
The slurry output from the bottom of the classification channel 002 can be filtered to obtain high-purity phosphogypsum products, the phosphogypsum products have little impurity content, and the phosphogypsum products are beneficial to being directly used as phosphogypsum for construction (namely industrial phosphogypsum); the phosphogypsum with higher impurity content is obtained after the slurry output from the top is filtered, but the impurities such as organic matters, fluoride, residual phosphorus and the like are beneficial to crops, and can be output as an agricultural phosphogypsum product.
In some embodiments, the sleeve structure may be a tertiary sleeve structure, mated with a tertiary aeration structure. The sleeve structure is formed by sequentially sleeving an inner pipeline 123, a middle pipeline 122 and an outermost pipeline 121, wherein a plurality of first communication holes 1231 are distributed on the pipe wall of the inner pipeline 123, and a plurality of second communication holes 1221 are distributed on the pipe wall of the middle pipeline 122. After entering from the inner layer piping 123, the extraction slurry enters the intermediate piping 122 from the first communication hole 1231, and then enters the outermost layer piping 121 from the second communication hole 1221. The top of the inner pipe 123, the intermediate pipe 122 and the outermost pipe 121 may be closed or open.
Further, a primary aeration structure 134 is provided in the inner pipe 123, a secondary aeration structure 135 is provided between the inner pipe 123 and the middle pipe 122, and a tertiary aeration structure 136 is provided between the middle pipe 122 and the outermost pipe 121, and the installation heights of the primary aeration structure 134, the secondary aeration structure 135 and the tertiary aeration structure 136 are gradually increased. The primary aeration structure 134, the secondary aeration structure 135 and the tertiary aeration structure 136 are all connected with the external aeration generator 133, that is, the tertiary aeration generator is mounted on the outer housing 110, the primary aeration structure 134 corresponds to the primary aeration generator, the secondary aeration structure 135 corresponds to the secondary aeration generator, and the tertiary aeration structure 136 corresponds to the tertiary aeration generator.
Specifically, referring to fig. 4 and 5, the aeration structures 130 each include a connection pipe 131 and a plurality of aeration disks 132, the plurality of aeration disks 132 are spaced apart on the connection pipe 131, and the connection pipe 131 is connected to an external aeration generator 133. The aeration disc 132 is structured like a shower head, and sprays out the gas-liquid mixture through a plurality of water outlet holes. The aeration generator 133 may be configured to pressurize the liquid and to introduce a gas into the pressurized liquid to form a gas-liquid mixture. The liquid filling device comprises a container, wherein a transfusion pipeline and a gas transmission pipeline are arranged on the container, liquid is firstly filled into the container, gas is filled into the top of the container through the gas transmission pipeline for pressurization, and then gas is filled into the bottom of the container through the gas transmission pipeline to form a gas-liquid mixed phase; and finally, introducing gas into the top of the container, opening an outlet valve, and outputting the gas-liquid mixed phase.
Further, the first communication holes 1231 are distributed from the top to the bottom of the inner pipeline 123, that is, the whole of the first communication holes 1231 is porous. The second communication holes 1221 are distributed in the region of the intermediate pipe 122 above the secondary aeration structure 135 so that the aerated slurry enters the outermost pipe 121 from above. The outermost pipe 121 may be provided with no communication hole, and the top of the outermost pipe 121 may be spaced from the top of the outer casing 110 to form an overflow port 007 that overflows from the outermost pipe 121 to the classification channel 002, so that slurry enters the classification channel 002 from the overflow port 007. Specifically, the opening ratio of the inner pipe 123 may be about 36%, and the opening ratio of the intermediate pipe 122 may be about 30%.
In some embodiments, the first super aeration device 100 further includes a bottom plate 140, the bottom plate 140 is disposed at the bottom of the sleeve structure, the feed port 001 is disposed on the bottom plate 140, and the position of the feed port 001 corresponds to the inner layer pipeline 123, and the feed can be from the center of the inner layer pipeline 123.
Further, a third outlet 005 is provided in the bottom plate 140 between the inner pipe 123 and the middle pipe 122, and a fourth outlet 006 is provided in the bottom plate 140 between the middle pipe 122 and the outermost pipe 121. The slurries output by the third discharge port 005 and the fourth discharge port 006 are the slurries with relatively low impurity content, and can be output as industrial phosphogypsum.
In some embodiments, the outermost pipe 121 is higher than the inner pipe 123 and the middle pipe 122, and a first dynamic settler 151 is disposed on top of the outermost pipe 121, and impurities are concentrated more in the slurry of the upper layer by using the first dynamic settler 151 to promote classification effect.
Similarly, a second dynamic settler 152 is arranged on the classification channel 002, the air-floating layer discharge outlet 003 is positioned above the second dynamic settler 152, and the dynamic settler is also arranged on the classification channel 002, so that the classification effect is further improved, and impurities are more concentrated on the upper-layer slurry.
Specifically, the first dynamic settler 151 and the second dynamic settler 152 are existing dynamic settlers, such as may be used in solving sludge settling in a sewage treatment process. As shown, the first dynamic settler 151 may be installed by means of a plate-like structure having upper and lower holes, and the second dynamic settler 152 may be installed by means of a plate-like structure having upper and lower holes, and the opening ratio may be 30%.
Specifically, the dimensions of each portion of the first super aeration air floatation device 100 are not limited, and may be designed according to the process requirements. The diameter of the outer housing 110 may be 900-1100mm, such as 1000mm; the diameter of the outermost tube 121 may be 600-800mm, such as 700mm; the diameter of the intermediate conduit 122 may be 400-600mm, such as 500mm; the diameter of the inner conduit may be 100-200mm, such as 150mm. The diameter of the feed inlet 001 can be 80mm, and the diameter of the discharge outlet can be 100mm.
As shown in FIG. 6, the height a of each part is 303mm; b, 180mm; c, 120mm; d, 230mm; e, 250mm; f, 230mm; g is 230mm; h, 330mm. The dimensions of the first dynamic settler 151 and the second dynamic settler 152 are shown in figure 6 in mm.
Specifically, the material of the first super aeration air floatation device 100 needs to resist corrosion of 20-45% phosphoric acid and 16-60% sulfuric acid, has the characteristics of high temperature resistance and high pressure resistance, is suitable for working under the working condition of 100 ℃ and 0.1MPa, and is recommended to be PC material, and PC pipe is selected as far as possible.
The super aeration float apparatus is not limited to the structure of fig. 4, and may be operated using the apparatus of fig. 7. The second super-aeration air floatation device 200 comprises a first bin 210, a second bin 220 and a third bin 230, wherein a first through window 211 communicated with the second bin 220 is arranged at the top of the first bin 210, a second through window 221 communicated with the third bin 230 is arranged on the side wall of the second bin 220, and a third through window 231 communicated with the first bin 210 is arranged on the side wall of the third bin 230. After entering from the first bin 210, the extraction slurry circulates back to the first bin 210 after passing through the second bin 220 and the third bin 230, ultra-exposure microbubbles are introduced into the first bin 210, agricultural phosphogypsum slurry is output from the top of the third bin 230, and building phosphogypsum slurry is output from the lower part of the ultra-exposure bin.
In some embodiments, the structure of the second super-exposure generator 400 in fig. 7 may be as shown in fig. 8, and the second super-exposure generator 400 in fig. 8 operates as follows: (1) Opening the fifth valve 421, feeding liquid or slurry into the generating vessel 410 using the liquid transfer line 420, and closing the fifth valve 421; (2) Opening the third valve 435 and the first valve 433 to pressurize the liquid in the generating vessel 410 through the compressed gas delivery line 430 and the top delivery line 431 to form a pressurizing area 401 at the top, and closing the first valve 433 after the pressure reaches the process requirement; (3) Opening the third valve 435 and the second valve 434, performing pressurized aeration into the pressurized liquid in the generating vessel 410 through the compressed gas delivery line 430 and the bottom delivery line 432 to form a pressurized gas-liquid mixture, and closing the third valve 435 and the second valve 434 after the process requirements are met; (4) The third valve 435, the first valve 433 and the fourth valve 441 are opened, compressed gas is pressurized to the top of the generation container 410 through the compressed gas delivery line 430 and the top delivery line 431, the pressurized gas-liquid mixture is outputted from the gas-liquid mixture output line 440, and the super-exposed liquid is delivered to the target area. The whole process utilizes the pressure detection mechanism 460 to detect the pressure, and the safety valve 450 alarms when the pressure exceeds a specified range.
By "overexposure" is meant that a gas-liquid mixture with pressure is formed, which differs from conventional bubbling mainly in pressurization.
The features and capabilities of the present invention are described in further detail below in connection with the examples.
The phosphorite used in the following examples was purchased from Guizhou phosphorite group.
Example 1
The embodiment provides a method for producing phosphogypsum by utilizing a wet-process phosphoric acid process at a low-carbon interface, wherein the process is shown in fig. 2, and the specific steps are as follows:
Mixing phosphorite and sulfuric acid aqueous solution with SO 3 concentration of 0.05g/mL, entering an extraction tank, controlling the liquid-solid ratio to be 3.0, controlling the temperature in the extraction tank to be about 90 ℃, entering a crystal growing tank after the extraction time in the extraction tank is 1.5h, and growing crystals in the crystal growing tank for 2.5h to obtain extraction slurry.
The extraction slurry is subjected to super aeration flotation by using the device shown in fig. 4 to obtain an air flotation layer and a surplus flotation layer, and the air flotation layer and the surplus flotation layer are respectively filtered to obtain filtrate and a filter cake. The method comprises the steps of floating in extraction slurry through super aeration, and introducing super aeration micro-bubbles generated by a high-pressure aeration device, wherein the super aeration micro-bubbles form a gas-liquid mixed phase in a liquid phase with pressure, the pressure of the liquid phase (namely aeration pressure) is 0.5MPa, the gas phase consists of micro-bubbles with the diameter of 2 mu m, the gas phase accounts for 8wt% of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is 12:100. the liquid phase is extraction slurry, and meanwhile, surfactant (C4-HTCC, HTCC represents chitosan quaternary ammonium salt and is a commercially available material) is added into the liquid phase, wherein the adding amount of the surfactant is 1.0mg/L.
In the embodiment, a conveying pipeline is also arranged in the extraction tank, a high-pressure aeration device is connected with the conveying pipeline, high-pressure aeration is carried out in the extraction tank, and the aeration composition is the same as that of the super-aeration floating stage.
Examples 2 to 6
The only difference from example 1 is that: the amounts of the surfactants C4-HTCC added were different, and the amounts of the surfactants C4-HTCC added in examples 2 to 6 were 0.5mg/L, 2.0mg/L, 3.0mg/L, 4.0mg/L, and 5.0mg/L, respectively.
Examples 7 to 10
The only difference from example 1 is that: the surfactant types used in examples 7 to 10 were C8-HTCC, C12-HTCC, cetyltrimethylammonium bromide and polydimethyldiallylammonium chloride in that order.
Examples 11 to 14
The only difference from example 1 is that: the pressures of the liquid phases were different, and the pressures of the liquid phases corresponding to examples 11 to 14 were 0.3MPa, 0.4MPa, 0.8MPa, and 1.0MPa in this order.
Examples 15 to 18
The only difference from example 1 is that: the proportions of the gas phase and the gas-liquid mixed phase are different, and the proportions of the examples 15-18 are 5%wt, 10%wt, 15%wt and 20%wt in sequence.
Comparative example 1
The only difference from example 1 is that: the super aeration flotation is changed into common micro-bubble flotation, namely, the liquid is not pressurized.
Comparative example 2
The only difference from example 1 is that: the process of fig. 1 is used for treatment.
Comparative example 3
The only difference from comparative example 2 is that: on the basis of fig. 1, common microbubbles are introduced in the extraction and seeding stages.
Comparative example 4
The only difference from example 1 is that: no surfactant was added.
Relevant indexes of the air flotation layer and the filter cake of the surplus layer are obtained after the treatment of examples 1-18 and comparative examples 1-4, as shown in table 1.
TABLE 1 relevant index of air flotation layer, residual layer cake
As can be seen from Table 1, compared with the existing process, the super aeration floating method provided by the embodiment of the invention can obviously improve the purity of the phosphogypsum of the floating residual layer, has lower impurity content of the phosphogypsum of the floating residual layer, and can meet the requirements of phosphogypsum raw materials for construction. The impurities contained in the phosphogypsum of the air floatation layer are all useful components for crops, and can be used as agricultural phosphogypsum.
Example 19
The embodiment provides a method for producing phosphogypsum by utilizing a wet-process phosphoric acid process at a low-carbon interface, wherein the process is shown in fig. 2, and the specific steps are as follows:
Mixing phosphorite and sulfuric acid aqueous solution with SO 3 concentration of 0.05g/mL, entering an extraction tank, controlling the liquid-solid ratio to be 3.0, controlling the temperature in the extraction tank to be about 90 ℃, entering a crystal growing tank after the extraction time in the extraction tank is 1.5h, and growing crystals in the crystal growing tank for 2.5h to obtain extraction slurry.
The extraction slurry is subjected to super aeration flotation by using the device shown in fig. 4 to obtain an air flotation layer and a surplus flotation layer, and the air flotation layer and the surplus flotation layer are respectively filtered to obtain filtrate and a filter cake. The method comprises the steps of floating in extraction slurry through super aeration, and introducing super aeration micro-bubbles generated by a high-pressure aeration device, wherein the super aeration micro-bubbles form a gas-liquid mixed phase in a liquid phase with pressure, the pressure of the liquid phase (namely aeration pressure) is 0.5MPa, the gas phase consists of micro-bubbles with the diameter of 2 mu m, the gas phase accounts for 8wt% of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is 12:100. the liquid phase is the pulp returning of the extraction system, and meanwhile, the surfactant (C4-HTCC) is added into the liquid phase, and the adding amount of the surfactant is 1.0mg/L.
In the embodiment, a conveying pipeline is also arranged in the crystal growing tank, a high-pressure aeration device is connected with the conveying pipeline, high-pressure aeration is carried out in the extraction tank, and the aeration composition is the same as that of the super-aeration floating stage.
Examples 20 to 24
The only difference from example 19 is that: the amounts of the surfactants C4-HTCC added were different, and the amounts of the surfactants C4-HTCC added in examples 20 to 24 were 0.5mg/L, 2.0mg/L, 3.0mg/L, 4.0mg/L, and 5.0mg/L, respectively.
Examples 25 to 28
The only difference from example 19 is that: the surfactant types used in examples 7 to 10 were C8-HTCC, C12-HTCC, cetyltrimethylammonium bromide and polydimethyldiallylammonium chloride in that order.
Examples 29 to 32
The only difference from example 19 is that: the pressures of the liquid phases were different, and the pressures of the liquid phases corresponding to examples 29 to 32 were 0.3MPa, 0.4MPa, 0.8MPa and 1.0MPa in this order.
Examples 33 to 36
The only difference from example 19 is that: the proportions of the gas phase and the gas-liquid mixed phase are different, and the proportions of the examples 33-36 are 5%wt, 10%wt, 15%wt and 20%wt in sequence.
Relevant indexes of the air flotation layer and the filter cake of the surplus layer are obtained after the treatment in examples 19-36, as shown in Table 2.
TABLE 2 relevant index of air flotation layer, residual layer cake
Example 37
The embodiment provides a method for producing phosphogypsum by utilizing a wet-process phosphoric acid process at a low-carbon interface, wherein the process is shown in fig. 2, and the specific steps are as follows:
Mixing phosphorite and sulfuric acid aqueous solution with SO 3 concentration of 0.05g/mL, entering an extraction tank, controlling the liquid-solid ratio to be 3.0, controlling the temperature in the extraction tank to be about 90 ℃, entering a crystal growing tank after the extraction time in the extraction tank is 1.5h, and growing crystals in the crystal growing tank for 2.5h to obtain extraction slurry.
The extraction slurry is subjected to super aeration flotation by using the device shown in fig. 4 to obtain an air flotation layer and a surplus flotation layer, and the air flotation layer and the surplus flotation layer are respectively filtered to obtain filtrate and a filter cake. The method comprises the steps of floating in extraction slurry through super aeration, and introducing super aeration micro-bubbles generated by a high-pressure aeration device, wherein the super aeration micro-bubbles form a gas-liquid mixed phase in a liquid phase with pressure, the pressure of the liquid phase (namely aeration pressure) is 0.5MPa, the gas phase consists of micro-bubbles with the diameter of 2 mu m, the gas phase accounts for 8wt% of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is 12:100. the liquid phase is the pulp returning of the extraction system, and meanwhile, the surfactant (C4-HTCC) is added into the liquid phase, and the adding amount of the surfactant is 1.0mg/L.
Note that: example 37 differs from example 1 only in that: the extraction tank is not filled with ultra-aeration micro-bubbles.
Examples 38 to 42
The only difference from example 37 is that: the amounts of the surfactants C4-HTCC added were different, and the amounts of the surfactants C4-HTCC added in examples 38-42 were 0.5mg/L, 2.0mg/L, 3.0mg/L, 4.0mg/L, and 5.0mg/L, respectively.
Examples 43 to 46
The only difference from example 37 is that: the surfactant types used in examples 43 to 46 were C8-HTCC, C12-HTCC, cetyltrimethylammonium bromide and polydimethyldiallylammonium chloride in that order.
Examples 47 to 50
The only difference from example 37 is that: the pressures of the liquid phases were different, and the pressures of the liquid phases corresponding to examples 47 to 50 were 0.3MPa, 0.4MPa, 0.8MPa, and 1.0MPa in this order.
Examples 51 to 54
The only difference from example 37 is that: the proportions of the gas phase and the gas-liquid mixed phase are different, and the proportions of the examples 51-54 are 5% wt, 10% wt, 15% wt and 20% wt in sequence.
Relevant indexes of the air flotation layer and the filter cake of the surplus layer are obtained after the treatment in examples 37-54, and are shown in Table 3.
TABLE 3 relevant index of air bearing layer, residual layer cake
Example 55
The only difference from example 1 is that: besides introducing the ultra-aeration micro-bubbles into the extraction tank, the ultra-aeration micro-bubbles are also introduced into the crystal growth tank, and the operation parameters of the extraction tank, the crystal growth tank and the ultra-aeration floating stage are consistent: the ultra-aeration micro-bubbles are formed in a liquid phase with pressure, wherein the pressure of the liquid phase (namely aeration pressure) is 0.5MPa, the gas phase consists of micro-bubbles with the diameter of 2 mu m, the gas phase accounts for 8 weight percent of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is 12:100. the liquid phase is the pulp returning of the extraction system, and meanwhile, the surfactant (C4-HTCC) is added into the liquid phase, and the adding amount of the surfactant is 1.0mg/L.
The indexes of the obtained air-floating layer and surplus layer filtration product in example 55 are shown in Table 4.
TABLE 4 relevant index of the filtration product of the air-bearing layer and the surplus layer obtained in example 55
Example 56
The only difference from example 37 is that: and arranging a flash evaporation device after the extraction tank and the crystal growth tank, adding a flash evaporation stage, and introducing ultra-aeration micro-bubbles in the flash evaporation stage.
In summer operation, a flash evaporation device as shown in fig. 9 is required to be arranged between the crystal growth tank and the classification system of the extraction system for further cooling operation due to the excessively high slurry temperature. The flash evaporation device comprises a flash evaporation body 301, wherein the flash evaporation body 301 is connected with a phosphoric acid slurry inlet 302 and a phosphoric acid slurry outlet, and can be connected with a first super-exposure generator 303, a first-stage aeration head 304 is arranged in the first super-exposure generator 303, and the generated gas-liquid mixed phase and the phosphoric acid slurry are mixed in the phosphoric acid slurry inlet 302 and then enter the flash evaporation body 301. For further super-exposure, a secondary aeration head 305 may also be provided within the flash body 301. Compared with flash evaporation in the traditional process, the pressure micro-bubble brought by the super-exposure device is more beneficial to flash evaporation, has less flash evaporation energy consumption and less waste gas generation under the same treatment capacity and treatment temperature difference, and greatly strengthens the flash evaporation cooling effect. The waste gas generated in the step is mainly phosphoric acid liquid entrained components, and can be adsorbed by adopting an air flotation layer filter cake subjected to subsequent grading treatment, so that the environmental pollution is reduced, and the resource utilization benefit is increased.
The specific operation of phosphoric acid production after introduction into the flash device is as follows: introducing the slurry after the extraction and crystal growth into a flash evaporation device, and simultaneously introducing ultra-aeration micro-bubbles generated by a high-pressure aeration device into the flash evaporation device, wherein a surfactant is added into an aeration system of the ultra-aeration micro-bubbles; and (3) performing super-aeration floating on the slurry obtained by the final flash evaporation by using a device shown in fig. 3 to obtain an air floating layer and a floating residue layer, and respectively filtering the air floating layer and the floating residue layer to obtain filtrate and a filter cake. The method comprises the steps of floating in extraction slurry through super aeration, and introducing super aeration micro-bubbles generated by a high-pressure aeration device, wherein the super aeration micro-bubbles form a gas-liquid mixed phase in a liquid phase with pressure, the pressure of the liquid phase (namely aeration pressure) is 0.5MPa, the gas phase consists of micro-bubbles with the diameter of 2 mu m, the gas phase accounts for 8wt% of the gas-liquid mixed phase, and the mass ratio of the gas-liquid mixed phase to the extraction slurry is 12:100. the liquid phase is the pulp returning of the extraction system, and meanwhile, the surfactant (C4-HTCC) is added into the liquid phase, and the adding amount of the surfactant is 1.0mg/L.
Experimental data show that under the condition of the same flash evaporation effect of the same phosphoric acid slurry, the energy consumption can be reduced by 25%, and the flash evaporation effect can be improved by 30% under the same energy consumption condition.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.