CN115893885B - Phosphogypsum pickling agent and phosphogypsum harmless treatment method - Google Patents
Phosphogypsum pickling agent and phosphogypsum harmless treatment method Download PDFInfo
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Abstract
The invention discloses a pickling agent of phosphogypsum and a harmless treatment method of phosphogypsum, wherein the pickling agent is composed of inorganic acid, organic acid and butyl acetate according to a certain proportion. The harmless part of phosphogypsumThe processing method comprises the following steps: s is S 1 Uniformly mixing fresh dry phosphogypsum with water to prepare phosphogypsum slurry; s is S 2 Immersing the phosphogypsum slurry in an immersing agent, concentrating and dehydrating after immersing to obtain immersed phosphogypsum; s is S 3 Screening and friction washing are carried out on the soaked phosphogypsum; s is S 4 Dewatering the phosphogypsum concentrated slurry subjected to friction water washing to obtain water-washed phosphogypsum; s is S 5 Oxidizing the washed phosphogypsum with an oxidant to obtain whitened phosphogypsum; s is S 6 And (3) carrying out acid-base neutralization treatment on the whitened phosphogypsum by using quicklime to obtain harmless high-purity high-whiteness regenerated gypsum. The method only effectively removes impurities such as soluble fluorine, phosphorus, organic matters and the like in phosphogypsum, can further remove eutectic phosphorus in phosphogypsum deeply, and simultaneously increases whiteness of the regenerated gypsum.
Description
Technical Field
The invention belongs to the technical field of phosphogypsum innocent treatment and resource utilization, and in particular relates to a pickling agent of phosphogypsum and a method for the phosphogypsum innocent treatment.
Background
Phosphogypsum is industrial solid waste residue generated when sulfuric acid is used for treating phosphorite in the wet-process phosphoric acid production process, and about 4.5-5 tons of phosphogypsum is produced per 1 ton of phosphoric acid produced. Phosphogypsum mainly comprises calcium sulfate dihydrate (CaSO) 4 ·2H 2 O), which belongs to class ii of general solid waste, is generally acidic (ph=1.9-5.3), and contains impurities such as non-decomposed phosphate rock, fluoride, organic matter, residual phosphoric acid, and the like. Worldwide, phosphogypsum stockpiling amounts are over 60 hundred million tons, and the annual growth rate is still about 2 hundred million tons, but the global phosphogypsum comprehensive utilization rate is only about 25%.
China is the first large phosphorus fertilizer producing country in the world and is also the first large phosphogypsum byproduct country. 85% of phosphorus chemical industry enterprises in the country are mainly distributed in Yangtze river basin, and focus is on Sichuan province, yunnan province, hubei province, anhui province and Guizhou province. In 2021, the stocking amount of phosphogypsum reaches 5 hundred million tons nationwide, 5000 ten thousand tons of phosphogypsum is newly added every year, and phosphogypsum becomes the second largest industrial solid waste in China. The phosphogypsum is piled up, so that a large amount of land is occupied, and the soluble fluorine, phosphorus, acid matters, organic matters and the like in the piled up body can cause persistent pollution to the soil, groundwater, surface water flow and other environments. Therefore, the harmless treatment and the comprehensive recycling of phosphogypsum are not slow.
Phosphogypsum calcium sulfate dihydrate (CaSO) 4 ·2H 2 O) is an important regenerated gypsum resource, but contains a plurality of harmful impurities such as phosphorus, fluorine, organic matters and the like, and seriously affects the material characteristics of the regenerated gypsum resource as a gypsum building material.
The phosphorus impurities in phosphogypsum are mainly divided into soluble phosphorus, eutectic phosphorus and indissolvable phosphorus. The main form of soluble phosphorus is H 3 PO 4 、H 2 PO 4 - 、HPO 4 2- 、PO 4 3- Four major classes, among which H has the greatest effect on gypsum performance 3 PO 4 The presence in an acidic environment will inhibit the growth of calcium sulfate. These soluble phosphorus will react with Ca when gypsum is hydrated 2+ The reaction generates insoluble calcium phosphate which covers the surface of phosphogypsum to prevent the phosphogypsum from being continuously dissolved out and hydrated, so that the setting and hardening time of the phosphogypsum is prolonged, the phosphogypsum is coarsened, the structure is loose, and the strength is reduced. Eutectic phosphorus is H in wet phosphoric acid production 2 PO 4 - 、HPO 4 2- Replacement of SO 4 2- Entering into eutectic crystal formed in calcium sulfate dihydrate crystal lattice, and dissolving eutectic phosphorus from crystal lattice during phosphogypsum hydration process, and mixing with Ca 2+ Production of poorly soluble Ca 3 (PO 4 ) 2 The modified phosphogypsum is covered on the surface of phosphogypsum powder, so that the crystallization supersaturation degree of the dihydrate gypsum is obviously reduced, the hydration rate is reduced, the initial setting time and the final setting time are prolonged, the coarsening of the structure is caused, the number of overlapping between crystals is reduced, the bending strength and the compressive strength of a hardened body are reduced, and eutectic phosphorus is difficult to remove by a general process method. Insoluble phosphorus is mainly prepared from Ca 3 (PO 4 ) 2 The form exists, and the phosphogypsum does not participate in the hydration reaction in the hydration process of the phosphogypsum due to the high melting point and stable chemical propertyAnd is inert.
Fluorine impurities in phosphogypsum are mainly divided into soluble fluorine and indissoluble fluorine. Soluble fluorine is one of the main forms affecting phosphogypsum performance, mainly as soluble fluorine F - The form exists, it will release certain acidity slowly in gypsum products, when the mass fraction exceeds 0.3%, will coarsen calcium sulfate dihydrate crystal, the molecular force between crystals is weakened, the structure is loose, and the phosphogypsum product strength is reduced. Insoluble fluorine CaF 2 、Na 2 SiF 6 The two forms exist, do not participate in hydration reaction, and have little influence on gelation performance.
The prior phosphogypsum innocent treatment method mainly comprises a water washing method, a flotation method, an acid washing method, a calcination method and the like, wherein some of the methods can not thoroughly remove soluble impurity impurities, eutectic phosphorus in the soluble impurity impurities can not be removed, and the whiteness after treatment is low, so that the recycling of phosphogypsum is influenced; in addition, some methods have large investment, high running cost and large practical application difficulty. How to remove impurities from phosphogypsum with low cost and high efficiency to produce high-quality regenerated gypsum, and to improve the recycling level of phosphogypsum, has become a technical problem to be solved urgently.
Disclosure of Invention
Based on the prior art, the invention provides the pickling agent for the phosphogypsum and the harmless treatment method for the phosphogypsum, which organically combine the pickling, oxidation, neutralization and other harmless treatment methods for the phosphogypsum, not only effectively remove the soluble fluorine, phosphorus, organic matters and other impurities in the phosphogypsum, but also deeply remove the eutectic phosphorus in the phosphogypsum, and simultaneously increase the whiteness of the phosphogypsum.
The technical scheme adopted for achieving the purposes of the invention is as follows:
the phosphogypsum leaching agent comprises the following components in percentage by mass:
inorganic acid 40-55%
Organic acid 40-55%
2% -5% of organic extractant.
Further, the inorganic acid is at least one selected from sulfuric acid and nitric acid.
Further, the mass fraction of the sulfuric acid is 20% -30%, and the mass fraction of the nitric acid is 25% -35%.
Further, the organic acid is at least one selected from citric acid and acetic acid.
Further, the organic extractant is at least one selected from butyl acetate and n-butanol.
A harmless treatment method of phosphogypsum comprises the following steps:
S 1 uniformly mixing fresh dry phosphogypsum with water to prepare phosphogypsum slurry;
S 2 immersing phosphogypsum slurry in the immersing agent, concentrating and dehydrating after immersing to obtain immersed phosphogypsum;
S 3 screening and friction washing are carried out on the soaked phosphogypsum;
S 4 dewatering the phosphogypsum concentrated slurry subjected to friction water washing to obtain water-washed phosphogypsum;
S 5 oxidizing the washed phosphogypsum with an oxidant to obtain whitened phosphogypsum;
S 6 and (3) carrying out acid-base neutralization treatment on the whitened phosphogypsum by using quicklime to obtain harmless high-purity high-whiteness regenerated gypsum.
Further, the water content of the fresh dry phosphogypsum is 10% -20%, and the water content of the phosphogypsum slurry is 40% -70%.
Further, the dosage of the leaching agent is 6-35kg/t of fresh dry phosphogypsum, and the leaching time is 30-60min.
Further, the water content of the immersed phosphogypsum is less than 40%, and the water content of the washed phosphogypsum is 20% -30%.
Further, the oxidant is hydrogen peroxide, the mass fraction of the hydrogen peroxide is 15% -30%, the consumption of the hydrogen peroxide is 5-15kg/t of water-washed phosphogypsum, and the oxidation treatment time is 20-60min.
Further, step S 6 And (3) regulating the pH value to 6.5-8.0 by using quicklime, and neutralizing for 10-20min.
Compared with the prior art, the invention has the advantages that:
1. the leaching agent can effectively remove the eutectic phosphorus in phosphogypsum, and can also react with fluoride to generate a complex which is easy to dissolve in water, thereby removing the eutectic phosphorus by subsequent water washing.
2. The pickling agent has the advantages of simple components, low cost, easy obtainment, low cost, no introduction of new harmful impurities, no influence on the subsequent recycling of phosphogypsum, and suitability for popularization and application.
3. The main pollutants, fluorine, phosphorus and organic matters in phosphogypsum are separated and removed through the leaching agent and the vibrating screen washing, the phosphogypsum is subjected to oxidation and acid-base neutralization treatment, and finally the harmless, high-purity and high-whiteness regenerated gypsum is obtained, the purity of the regenerated gypsum can exceed 90%, the whiteness of the regenerated gypsum exceeds 85%, the quality of the regenerated gypsum is superior to the national standard of primary natural gypsum and primary phosphogypsum, the regenerated gypsum can be stacked harmlessly, the natural gypsum ore can be replaced, the regenerated gypsum can be used as a raw material of the construction gypsum, and meanwhile, the sieved gravel can be used as construction materials such as water permeable bricks, concrete mortar and the like.
4. The harmless treatment method is simple, convenient to operate, low in running and investment cost, high in controllability and convenient for industrialized application.
Detailed Description
The present invention is described in detail below with reference to specific examples, but these examples are not to be construed in any way as limiting the scope of the present invention.
Example 1
The phosphogypsum leaching agent consists of the following components in percentage by mass:
sulfuric acid 48.8%
Citric acid 48.8%
2.4 percent of butyl acetate,
the mass fraction of the sulfuric acid is 25%.
Example 2
The phosphogypsum leaching agent consists of the following components in percentage by mass:
sulfuric acid 46.0%
Citric acid 50.5%
3.5 percent of n-butyl alcohol,
the mass fraction of the sulfuric acid is 30%.
Example 3
The phosphogypsum leaching agent consists of the following components in percentage by mass:
nitric acid 40.0%
Acetic acid 55.0%
5.0 percent of n-butyl alcohol,
the mass fraction of the nitric acid is 35%.
Example 4
The phosphogypsum leaching agent consists of the following components in percentage by mass:
nitric acid 46.7%
Acetic acid 48.3%
Butyl acetate 5.0 percent,
the mass fraction of the nitric acid is 30%.
Example 5
S 1 100g of fresh dry phosphogypsum of a phosphorite enterprise A in Hubei province is taken, the whiteness is 38.96%, the water content is 11.30%, and the pH is 2.3. 80ml of water was added to the fresh dry phosphogypsum and stirred on a magnetic stirrer for 5min to prepare phosphogypsum slurry with a water content of 50.72%.
S 2 Sulfuric acid, citric acid and butyl acetate are taken according to the proportion of the example 1, and are stirred and mixed uniformly to prepare the leaching agent.
S 3 Adding 3g of leaching agent into phosphogypsum slurry, stirring and leaching for 40min, then placing into a centrifuge, concentrating and dehydrating for 10min at 3000rad/min, pouring out the upper liquid to obtain leached phosphogypsum, wherein the water content of the leached phosphogypsum is less than 40%, and the upper liquid is enriched with impurities such as phosphorus, fluorine, organic matters and the like.
The three components of sulfuric acid, citric acid and butyl acetate in the leaching agent are matched with each other to realize synergistic effect, so that eutectic phosphorus in phosphogypsum can be effectively removed, and simultaneously, the eutectic phosphorus can also react with fluoride to generate a complex which is easy to dissolve in water, and organic impurities in phosphogypsum are removed by extraction and then are removed by subsequent water washing.
S 4 Adding 80ml of water into the soaked phosphogypsum, sufficiently and uniformly oscillating the soaked phosphogypsum and the water for 2min by using an oscillator, then carrying out vibration friction filtration by using a 20-mesh vibrating screen, and carrying out centrifugal dehydration on the solid obtained by filtration to obtain the water-washed phosphogypsum. The step separates the phosphogypsum from minerals, gravel and the like which are not completely decomposed in the phosphoric acid extraction process, and the vibrating screen can also play a role in scrubbing the phosphogypsum, so that the soluble impurities adsorbed on the surface can be removed more effectively.
S 5 Adding 20ml of water into the washed phosphogypsum, oscillating for 2min by using an oscillator, dispersing and uniformly mixing, then adding 1.5g of 30% hydrogen peroxide, and stirring for 40min by using a magnetic stirrer to obtain a solid-liquid mixture containing the whitened phosphogypsum.
S 6 Adding 2.4g of quicklime (CaO) into the solid-liquid mixture containing the whitened phosphogypsum, stirring and reacting for 20min, adjusting the pH value to 6.8, dehydrating by using a centrifuge, and air-drying by using a 45 ℃ oven until the constant weight is achieved, thus obtaining the harmless high-purity high-whiteness regenerated gypsum.
The mass fraction change conditions of the main components before and after the phosphogypsum innocent treatment in the embodiment are shown in table 1:
TABLE 1 mass fraction comparison of Main Components before and after phosphogypsum innocent treatment
As is clear from Table 1, P after innocent treatment 2 O 5 The contents of impurities such as F, mgO and the like are obviously reduced, and calcium oxide and SO 3 The content of the usable component increases. Therefore, the method can obviously remove the impurities such as phosphorus, fluorine and the like in phosphogypsum, and improve the content of available components.
Example 6
S 1 Taking 100g of fresh dry phosphogypsum of a phosphorite enterprise B in Hubei province, wherein the whiteness is 42.56%,the water content was 12.14% and the pH was 2.8. 80ml of water was added to the fresh dry phosphogypsum, and the mixture was stirred on a magnetic stirrer for 5 minutes to prepare phosphogypsum slurry with a water content of 51.19%.
S 2 Sulfuric acid, citric acid and butyl acetate are taken according to the proportion of the example 1, and are stirred and mixed uniformly to prepare the leaching agent.
S 3 Adding 3g of leaching agent into phosphogypsum slurry, stirring and leaching for 30min, then placing into a centrifuge, concentrating and dehydrating for 10min at 3000rad/min, pouring out the upper liquid to obtain leached phosphogypsum, wherein the concentration of the leached phosphogypsum is more than 60%.
S 4 Adding 80ml of water into the soaked phosphogypsum, sufficiently and uniformly oscillating the soaked phosphogypsum and the water for 2min by using an oscillator, then carrying out vibration friction filtration by using a 20-mesh vibrating screen, and carrying out centrifugal dehydration on the solid obtained by filtration to obtain the water-washed phosphogypsum.
S 5 Adding 20ml of water into the washed phosphogypsum, oscillating for 2min by using an oscillator, dispersing and uniformly mixing, then adding 1.5g of 30% hydrogen peroxide, and stirring for 40min by using a magnetic stirrer to obtain a solid-liquid mixture containing the whitened phosphogypsum.
S 6 Adding 2.2g of quicklime (CaO) into the solid-liquid mixture containing the whitened phosphogypsum, stirring and reacting for 20min, adjusting the pH value to 6.6, dehydrating by using a centrifuge, and air-drying by using a 45 ℃ oven until the constant weight is achieved, thus obtaining the harmless high-purity high-whiteness regenerated gypsum.
The mass fraction change conditions of the main components before and after the phosphogypsum innocent treatment in the embodiment are shown in table 2:
TABLE 2 mass fraction comparison of Main Components before and after phosphogypsum innocent treatment
As is clear from Table 2, P after innocent treatment 2 O 5 The contents of impurities such as F, mgO and the like are obviously reduced, and calcium oxide and SO 3 In terms of the content of the components to be usedLifting. Therefore, the method can obviously remove the impurities such as phosphorus, fluorine and the like in phosphogypsum, and improve the content of available components.
The indexes of the regenerated gypsum obtained by innocent treatment in examples 5-6 are compared with the national standards of first-class natural gypsum (GB/T5483-2008) and first-class phosphogypsum (GB/T23456-018), and the method is specifically shown in FIG. 3:
TABLE 3 comparison of phosphogypsum before and after innocent treatment with national standard
Remarks: nd means that it is not detected
As can be seen from Table 3, the regenerated gypsum obtained by treating fresh dry phosphogypsum by the method has various indexes which completely meet the standards of the primary natural gypsum and the primary phosphogypsum, has high whiteness, excellent quality and meets the requirements of building gypsum on raw materials.
Claims (7)
1. The phosphogypsum pickling agent is characterized by comprising the following components in percentage by mass:
sulfuric acid 40-55%
Citric acid 40% -55%
2% -5% of butyl acetate.
2. The phosphogypsum leaching agent of claim 1, wherein: the mass fraction of the sulfuric acid is 20% -30%.
3. The harmless treatment method of phosphogypsum is characterized by comprising the following steps:
S 1 uniformly mixing fresh dry phosphogypsum with water to prepare phosphogypsum slurry;
S 2 immersing phosphogypsum slurry in the immersing agent in claim 1, and concentrating and dehydrating centrifugally after immersing to obtain immersed phosphogypsum;
S 3 screening and grinding the soaked phosphogypsumWiping and washing;
S 4 dewatering the phosphogypsum concentrated slurry subjected to friction water washing to obtain water-washed phosphogypsum;
S 5 oxidizing the washed phosphogypsum with an oxidant to obtain whitened phosphogypsum;
S 6 and (3) carrying out acid-base neutralization treatment on the whitened phosphogypsum by using quicklime to obtain harmless high-purity high-whiteness regenerated gypsum.
4. The method for innocuous treatment of phosphogypsum according to claim 3, wherein: the water content of the fresh dry phosphogypsum is 10% -20%, and the water content of the phosphogypsum slurry is 40% -70%.
5. The method for innocuous treatment of phosphogypsum according to claim 3, wherein: the dosage of the leaching agent is 6-35kg/t of fresh dry phosphogypsum, and the leaching time is 30-60min.
6. The method for innocuous treatment of phosphogypsum according to claim 3, wherein: the oxidant is hydrogen peroxide, the mass fraction of the hydrogen peroxide is 15% -30%, the consumption of the hydrogen peroxide is 5-15kg/t of water-washed phosphogypsum, and the oxidation treatment time is 20-60min.
7. The method for innocuous treatment of phosphogypsum according to claim 3, wherein: step S 6 And (3) regulating the pH value to 6.5-8.0 by using quicklime, and neutralizing for 10-20min.
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| CN106977123A (en) * | 2017-03-31 | 2017-07-25 | 合肥学院 | A kind of citric acid for being used to remove impurity fluorine in ardealite adds water the process washed |
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