CN112794754A - Method for purifying phosphogypsum by leaching water and jointly producing water-soluble fertilizer and liquid fertilizer - Google Patents
Method for purifying phosphogypsum by leaching water and jointly producing water-soluble fertilizer and liquid fertilizer Download PDFInfo
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- CN112794754A CN112794754A CN202011471998.5A CN202011471998A CN112794754A CN 112794754 A CN112794754 A CN 112794754A CN 202011471998 A CN202011471998 A CN 202011471998A CN 112794754 A CN112794754 A CN 112794754A
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- C—CHEMISTRY; METALLURGY
- C05—FERTILISERS; MANUFACTURE THEREOF
- C05G—MIXTURES OF FERTILISERS COVERED INDIVIDUALLY BY DIFFERENT SUBCLASSES OF CLASS C05; MIXTURES OF ONE OR MORE FERTILISERS WITH MATERIALS NOT HAVING A SPECIFIC FERTILISING ACTIVITY, e.g. PESTICIDES, SOIL-CONDITIONERS, WETTING AGENTS; FERTILISERS CHARACTERISED BY THEIR FORM
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Abstract
The invention belongs to the field of chemical engineering, relates to comprehensive utilization of phosphogypsum and leaching water of a phosphogypsum yard, and particularly relates to a method for purifying phosphogypsum by leaching water and producing a water-soluble fertilizer and a liquid fertilizer jointly. The method comprises the following specific steps: the leaching water is divided into concentrated water and permeate water after being treated by a reverse osmosis device, the concentrated water is preheated and then repulped with fresh phosphogypsum, a flocculating agent and quicklime are added in the repulping process to adjust the pH value and defluorination, the high-temperature repulping is carried out and then the filtration is carried out while the filtration is hot, and a filter cake is the purified phosphogypsum and can be comprehensively utilized after being calcined; and (4) exchanging heat and reducing the temperature of the filtrate by concentrated water, and preheating the concentrated water. And cooling the high-temperature repulped filtrate and then feeding the cooled filtrate into a low-temperature sedimentation tank. The supernatant is sent to downstream for further processing and producing liquid compound fertilizer, and the sediment is sent to a water-soluble fertilizer device for compounding water-soluble fertilizer. The leaching water and the phosphogypsum are comprehensively recycled, waste is changed into valuable, waste of heat energy is avoided, and energy is saved.
Description
Technical Field
The invention belongs to the field of chemical engineering, relates to comprehensive utilization of leaching water in a phosphogypsum yard, and particularly relates to a method for purifying phosphogypsum by leaching water and producing a water-soluble fertilizer and a liquid fertilizer jointly.
Background
The wet-process phosphoric acid production is a process technology for extracting phosphoric acid from phosphate ore by using the phosphate ore and sulfuric acid as raw materials and by using a wet process, and the development of the technology makes a revolutionary contribution to the extraction of the phosphate ore. As industrial solid waste, the public smells the color change of the phosphogypsum, and the post-treatment problem is widely concerned by various social circles all the time, but the problem of large-scale resource utilization is still needed to be solved by being limited by technology, market and capital. At present, gypsum pretreatment methods are various, the main flow is water washing, calcining, flotation, ball milling, aging, screening and the like, but a large amount of phosphogypsum is still stockpiled in the open air. At present, fresh phosphogypsum can be recycled and used in the production fields of road filling, gypsum plasterboards, gypsum blocks and other building products. Compared with natural gypsum, the main indexes of the building materials are influenced by the phosphogypsum by various impurities, wherein the impurities which have larger influence comprise soluble phosphorus, fluorosilicate and the like, which can corrode structural materials of buildings and prolong the setting time of the structural materials of the buildings. If the soluble impurities are converted into the insoluble impurities, the indexes such as the compressive strength, the setting time and the like of the gypsum product prepared from the phosphogypsum can be improved.
Moreover, because the phosphogypsum has strong acidity, new problems, namely leaching water, can be caused by rain wash in open-air stockpiling. If the leaching water seeps underground, the leaching water can directly pollute local water sources, especially in flood seasons, and the anti-seepage environment-friendly treatment of the leaching water can also bear the burden of enterprises.
Disclosure of Invention
The invention aims to overcome the defects that the stacked phosphogypsum is difficult to utilize and the leaching water treatment cost is high in the prior art, and provides a method for purifying the phosphogypsum by leaching water and producing a water-soluble fertilizer and a liquid fertilizer jointly.
In order to solve the technical problem, the technical scheme is that the method for purifying phosphogypsum by leaching water and producing the water-soluble fertilizer and the liquid fertilizer jointly comprises the following steps:
s1, treating the eluviated water by a reverse osmosis device to obtain concentrated water and permeated water;
s2, mixing concentrated water and fresh phosphogypsum according to the mass ratio of (1.5-2.0):1, heating the mixture to 60-80 ℃, adding a flocculating agent and quicklime, stirring at the speed of 200-;
and S3, cooling the high-temperature repulped filtrate in a low-temperature sedimentation tank, separating out crystal sediment, using the supernatant as a liquid fertilizer, and using the lower-layer sediment as a water-soluble fertilizer.
The method for purifying the phosphogypsum by using the leaching water and producing the water-soluble fertilizer and the liquid fertilizer jointly is further improved as follows:
preferably, the purified phosphogypsum obtained in the step S2 is added with quicklime and then is reused as a cement retarder or calcined phosphogypsum.
Preferably, the mixture of concentrated water and fresh phosphogypsum is heated in step S2 using steam heating.
Preferably, PAM and PAC are added in combination as a flocculant in step S2, the amount of flocculant added being 25g to 1 ton of fresh phosphogypsum and concentrated water mixture.
Preferably, the quicklime in step S2 is lime milk with a mass fraction of 13%, and the lime milk is added to the mixture of fresh phosphogypsum and concentrated water in an amount to maintain the pH of the mixture at 3.5-4.0.
Preferably, 1L of eluviation water is treated by the reverse osmosis device in the step S1 to obtain 0.4-0.5L of permeated water.
Preferably, the concentrated water in step S2 is pre-heated to 25-45 ℃ before being mixed with fresh phosphogypsum.
Preferably, the high temperature repulped filtrate of step S3 is used to preheat the concentrated water of step S2 via heat exchange means.
Compared with the prior art, the invention has the beneficial effects that:
1) the method utilizes the leaching water to evolve the phosphogypsum and jointly produce the water-soluble fertilizer and the liquid fertilizer. The main component of the phosphogypsum is calcium sulfate dihydrate, and also contains a small amount of undecomposed phosphorite, acid insoluble substances, organic matters, iron-aluminum compounds, calcium fluoride, unwashed phosphoric acid and the like. After the content of fluorine and aluminum elements is reduced, most soluble substances can be absorbed by plants, and the soluble substances have potential as fertilizers. One of the most critical processes in the resource utilization of the phosphogypsum is impurity removal. The solubility of soluble salt impurities contained in the phosphogypsum water washing liquor increases with increasing temperature. The invention washes the phosphogypsum with aqueous solution under high temperature, and can dissolve more soluble salt impurities with a small amount of water. The method meets the requirement of closed management of a later-stage phosphogypsum storage yard, and replaces natural rainfall to wash the phosphogypsum by a repulping and water washing purification method, so that the quality of the phosphogypsum is improved.
2) The phosphogypsum washing has a great disadvantage that washing sewage is difficult to treat. If the process water is directly used for washing, a large amount of water resources are consumed and the post-treatment cost is extremely high. If the process water is not replaced and is always circulated in the system, the concentration of impurities is increased, and finally, the pipeline is blocked by scale; the invention carries out the permeation treatment on the eluviation water to obtain concentrated water and permeated water, the removal rate of the reverse osmosis treatment device on the total phosphorus in the eluviation water reaches more than 99.7 percent, the concentration of the total phosphorus in the permeated water is 10.6-11.5mg/L, the concentration of fluoride is 50.2-51.6mg/L, the pH value is 2.8-3.2, and the concentrated water and the permeated water can be directly recycled; the concentrated water is heated to wash out the phosphogypsum impurities, thereby facilitating the purification and the reutilization of the phosphogypsum and the reutilization of the components in the leaching water. The purification system can continuously operate without supplementing a large amount of process water, thereby saving a large amount of sewage treatment cost and reducing the influence on the water balance of the device.
3) The high-temperature repulped filtrate is subjected to heat exchange and cooling by the concentrated water, and the concentrated water is preheated, so that waste heat is highly utilized, waste of heat energy is avoided, and energy is saved. Reducing the cooling time and increasing the cooling crystallization amount of soluble salt in the high-temperature repulped filtrate.
4) The phosphogypsum water washing solution and the eluviation water contain rich plant absorbable mineral substances, enter the high-temperature repulping filtrate, and the supernatant can be used as a liquid fertilizer after cooling and precipitation, and the precipitate can be used as a water-soluble fertilizer, so that waste is changed into valuable.
Drawings
FIG. 1 is a flow chart of the process of the present invention for purifying phosphogypsum with leaching water and for co-producing water soluble fertilizer and liquid fertilizer;
FIG. 2 is a diagram illustrating the process of cooling and crystallizing the soluble substance in the high temperature repulped filtrate.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to embodiments, and all other embodiments obtained by a person of ordinary skill in the art without any creative effort based on the embodiments of the present invention belong to the protection scope of the present invention.
Example 1
As shown in fig. 1, a method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly comprises the following specific steps:
s1, treating the eluviated water by a reverse osmosis device, wherein the filtration rate is 1.5L/h, so as to obtain concentrated water and permeated water, and 1L of eluviated water corresponds to 0.4-0.5L of permeated water;
s2, preheating concentrated water, mixing the preheated concentrated water with fresh phosphogypsum according to the mass ratio of (1.5-2.0):1, heating the mixture to 60-80 ℃ by using steam, jointly adding PAM and PAC as flocculating agents, adding 25g of the flocculating agents into 1 ton of the mixture, adding 13% by mass of lime milk as quicklime, wherein the addition of the quicklime is suitable for maintaining the pH of the mixture at 3.5-4.0, stirring at the speed of 200-300r/min, re-pulping for 20-30 minutes, and filtering after the reaction is finished to obtain purified phosphogypsum and high-temperature re-pulping filtrate;
and S3, preheating the concentrated water in the step S1 by using the high-temperature repulped filtrate through heat exchange equipment, cooling the high-temperature repulped filtrate, then feeding the cooled high-temperature repulped filtrate into a low-temperature sedimentation tank, separating out crystal precipitates, using the supernatant as a liquid fertilizer, and using the lower-layer sediment as a water-soluble fertilizer.
Through determination, the removal rate of the reverse osmosis treatment device on the total phosphorus in the eluviation water reaches more than 99.7 percent, the concentration of the total phosphorus in the permeated water is 10.6-11.5mg/L, the concentration of fluoride is 50.2-51.6mg/L, the pH value is 2.8-3.2, and the total phosphorus can be directly discharged or utilized; fresh phosphogypsum is subjected to defluorination and flocculation impurity removal treatment in high-temperature repulping, the content of fluorine element in the purified phosphogypsum is greatly reduced, and the purified phosphogypsum can be reused as a cement retarder or calcined phosphogypsum after quicklime is added; the phosphogypsum water washing liquid and rich plant absorbable minerals contained in the eluviation water enter the high-temperature repulping filtrate, crystals are separated out when the high-temperature repulping filtrate is cooled, and the supernatant can be used as a liquid fertilizer after being treated, and the precipitate can be used as a water-soluble fertilizer.
Example 2
FIG. 2 is a schematic diagram of the cooling crystallization of soluble substances in the high-temperature repulped filtrate. The solubility of the soluble salt impurities is higher in the high temperature repulped filtrate at 60-80 ℃ than in the normal temperature repulped filtrate. Therefore, after the high-temperature repulping filtrate is cooled through heat exchange with concentrated water, part of soluble matters dissolved in the repulping filtrate at the temperature of 60 ℃ are separated out, and separated out crystals and supernatant liquid are obtained, wherein the supernatant liquid contains part of the soluble matters. The components of the water soluble fertilizer are respectively detected, the supernatant can be sent to downstream for further processing to generate a liquid compound fertilizer, and the precipitate can be sent to a water soluble fertilizer device for compounding the water soluble fertilizer.
It should be understood by those skilled in the art that the foregoing is only illustrative of several embodiments of the invention, and not of all embodiments. It should be noted that many variations and modifications are possible to those skilled in the art, and all variations and modifications that do not depart from the gist of the invention are intended to be within the scope of the invention as defined in the appended claims.
Claims (8)
1. A method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly is characterized by comprising the following steps:
s1, treating the eluviated water by a reverse osmosis device to obtain concentrated water and permeated water;
s2, mixing concentrated water and fresh phosphogypsum according to the mass ratio of (1.5-2.0):1, heating the mixture to 60-80 ℃, adding a flocculating agent and quicklime, stirring at the speed of 200-;
and S3, cooling the high-temperature repulped filtrate in a low-temperature sedimentation tank, separating out crystal sediment, using the supernatant as a liquid fertilizer, and using the lower-layer sediment as a water-soluble fertilizer.
2. The method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly according to claim 1, is characterized in that the purified phosphogypsum of the step S2 is added with quick lime and then used as cement retarder or calcined phosphogypsum for reutilization.
3. The method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly by using the leaching water as claimed in claim 1, is characterized in that the mixture of concentrated water and fresh phosphogypsum is heated by using steam heating in step S2.
4. The method for purifying phosphogypsum by leaching water and jointly producing water-soluble fertilizer and liquid fertilizer according to claim 1 is characterized in that PAM and PAC are jointly added as flocculating agents in step S2, and the addition amount of the flocculating agents in 1 ton of fresh phosphogypsum and concentrated water mixture is 25 g.
5. The method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly according to claim 1, characterized in that the quicklime in step S2 is lime milk with a mass fraction of 13%, and the lime milk is added in the mixture of fresh phosphogypsum and concentrated water in an amount that is suitable for maintaining the pH of the mixture between 3.5 and 4.0.
6. The method for purifying phosphogypsum and producing water-soluble fertilizer and liquid fertilizer jointly by using eluviated water according to claim 1, characterized in that 1L of eluviated water is treated by the reverse osmosis device in the step S1 to obtain 0.4-0.5L of permeated water.
7. The method for purifying phosphogypsum by leaching water and producing water-soluble fertilizer and liquid fertilizer jointly according to claim 1, is characterized in that the concentrated water in the step S2 is preheated to 25-45 ℃ and then mixed with fresh phosphogypsum.
8. The method for purifying phosphogypsum with leaching water and jointly producing water-soluble fertilizer and liquid fertilizer according to claim 7 is characterized in that the high-temperature repulped filtrate in step S3 is used to preheat the concentrated water in step S2 through heat exchange equipment.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011471998.5A CN112794754A (en) | 2020-12-15 | 2020-12-15 | Method for purifying phosphogypsum by leaching water and jointly producing water-soluble fertilizer and liquid fertilizer |
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| CN202011471998.5A CN112794754A (en) | 2020-12-15 | 2020-12-15 | Method for purifying phosphogypsum by leaching water and jointly producing water-soluble fertilizer and liquid fertilizer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115557719A (en) * | 2022-08-16 | 2023-01-03 | 湖北祥云(集团)化工股份有限公司 | Comprehensive treatment method of phosphogypsum |
| CN115872641A (en) * | 2022-12-22 | 2023-03-31 | 武汉工程大学 | Curing agent for curing and removing soluble phosphorus and soluble fluorine in phosphogypsum and application thereof |
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| CN102731001A (en) * | 2012-07-25 | 2012-10-17 | 广西鹿寨凯浩鹿宝新型建材有限公司 | Phosphogypsum composite pretreatment technique |
| BR102012012961A2 (en) * | 2012-05-30 | 2015-09-15 | Gabriel Estevam Domingos | eco-friendly phosphogypsum paint |
| CN210481004U (en) * | 2019-03-08 | 2020-05-08 | 安徽六国化工股份有限公司 | Reverse osmosis treatment device for phosphorus-containing eluviation water |
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2020
- 2020-12-15 CN CN202011471998.5A patent/CN112794754A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101386909A (en) * | 2007-09-12 | 2009-03-18 | 贵州光大能源发展有限公司 | Method for extracting rare-earth from ardealite |
| BR102012012961A2 (en) * | 2012-05-30 | 2015-09-15 | Gabriel Estevam Domingos | eco-friendly phosphogypsum paint |
| CN102731001A (en) * | 2012-07-25 | 2012-10-17 | 广西鹿寨凯浩鹿宝新型建材有限公司 | Phosphogypsum composite pretreatment technique |
| CN210481004U (en) * | 2019-03-08 | 2020-05-08 | 安徽六国化工股份有限公司 | Reverse osmosis treatment device for phosphorus-containing eluviation water |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115557719A (en) * | 2022-08-16 | 2023-01-03 | 湖北祥云(集团)化工股份有限公司 | Comprehensive treatment method of phosphogypsum |
| CN115557719B (en) * | 2022-08-16 | 2023-08-15 | 湖北祥云(集团)化工股份有限公司 | Comprehensive treatment method of phosphogypsum |
| WO2024037298A1 (en) * | 2022-08-16 | 2024-02-22 | 湖北祥云(集团)化工股份有限公司 | Integrated treatment method for phosphogypsum |
| CN115872641A (en) * | 2022-12-22 | 2023-03-31 | 武汉工程大学 | Curing agent for curing and removing soluble phosphorus and soluble fluorine in phosphogypsum and application thereof |
| CN115872641B (en) * | 2022-12-22 | 2024-03-29 | 武汉工程大学 | Curing agent for curing and removing soluble phosphorus and soluble fluorine in phosphogypsum and application thereof |
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