A solid synergistic recycled material of phosphogypsum, sawdust and sludge and its regeneration process and application

Abstract

The present application relates to the technical field of phosphogypsum solid waste treatment, and specifically discloses a solid-state synergistic regeneration material of phosphogypsum, saw mud and sludge, and its regeneration process and application. A solid-state synergistic regeneration material of phosphogypsum, saw mud and sludge, characterized in that it is mainly made of the following raw materials in parts by weight: 120-150 parts of phosphogypsum, 50-65 parts of saw mud, 20-30 parts of sludge, 3-5 parts of lime, 2-3.5 parts of cement, 1-2 parts of calcium citrate, 0.5-1 parts of aluminum sulfate, and 7-10 parts of chelating agent; the chelating agent is composed of starch and organic acid iron in a mass ratio of (5-8): (15-20). The solid-state synergistic regeneration material of phosphogypsum, saw mud and sludge of the present application has the advantage that fluorine and phosphorus are not easily separated twice.

Description

Technical Field

[0001] The present application relates to the technical field of phosphogypsum solid waste treatment, and more specifically, to a solid-state synergistic recycled material of phosphogypsum, saw mud and sludge, and a regeneration process and application thereof. Background Art

[0002] Phosphogypsum is a byproduct of wet phosphoric acid production, and its main component is calcium sulfate dihydrate. With the continuous growth of domestic demand for ammonium phosphate and high-concentration phosphate fertilizers, the development of the wet phosphoric acid industry has been greatly promoted, but at the same time, more phosphogypsum solid waste has been generated. How to effectively utilize phosphogypsum and reduce the pollution of phosphogypsum solid waste to the environment is a long-term exploration issue.

[0003] In addition to harmful components such as acidic substances and heavy metals, phosphogypsum solid waste also contains water-soluble impurities such as fluorine and phosphorus, which will seriously limit the industrial application of phosphogypsum. Among them, fluoride ions will promote the coagulation of gypsum, and fluoride ions are also corrosive ions, which have an adverse effect on the strength of gypsum. Water-soluble phosphorus will cause great harm to the environment, and when phosphogypsum containing more soluble phosphorus is used in construction, it will also cause the strength of the building structure to decrease.

[0004] At present, the solid waste treatment methods of phosphogypsum mainly include water washing method, lime neutralization method, calcination method, etc. For example, Chinese patent application with application publication number CN111170668A discloses a calcination treatment method of phosphogypsum and the use of the obtained phosphogypsum. The calcination treatment method comprises the following steps: (1) mixing phosphogypsum containing phosphorus and fluorine with an additive to obtain a mixture; (2) calcining the mixture obtained in step (1) to obtain a phosphogypsum product that meets the specified requirements.

[0005] For another example, a Chinese patent application with application publication number CN103073207A discloses a method for harmlessly treating phosphogypsum and converting it into a recycled gypsum resource, wherein ultrafine cement clinker powder with a specific surface area greater than or equal to 300 m2 / kg is used as a phosphogypsum modifier; the phosphogypsum modifier is mixed with freshly discharged phosphogypsum in a mass ratio of 1:9-2:8, and the mixture is homogenized and stirred with a special homogenizer to obtain the obtained gypsum.

[0006] Although the above-mentioned method for treating phosphogypsum solid waste reduces the content of free fluorine and phosphorus ions to a certain extent, in the subsequent use process, the fixation of fluorine and phosphorus ions is poor and segregation is prone to occur, causing secondary pollution. Summary of the invention

[0007] In order to reduce the fluorine and phosphorus content in phosphogypsum solid waste and reduce secondary segregation pollution, the present application provides a solid-state synergistic recycled material of phosphogypsum, saw mud and sludge, and a regeneration process and application thereof.

[0008] In the first aspect, the present application provides a solid-state synergistic recycled material of phosphogypsum, sawdust and sludge, which adopts the following technical solution:

[0009] A solid-state synergistic recycled material of phosphogypsum, saw mud and sewage sludge is mainly made of the following raw materials in parts by weight: 120-150 parts of phosphogypsum, 50-65 parts of saw mud, 20-30 parts of sewage sludge, 10-15 parts of lime, 2-3.5 parts of cement, 1-2 parts of calcium citrate, 0.5-1 parts of aluminum sulfate and 7-10 parts of chelating agent; the chelating agent is composed of starch and organic acid iron in a mass ratio of (5-8):(15-20).

[0010] By adopting the above technical scheme, the components such as phosphogypsum, saw mud, sludge, lime and water are evenly mixed to form a viscous slurry. The solid particle components such as lime, cement, saw mud and sludge can neutralize the residual acidic substances in the phosphogypsum, increase the pH value of the slurry, and also adsorb most of the heavy metal ions to reduce the harm of phosphogypsum. In addition, during the regeneration process, the starch in the chelating agent can form a large number of microspheres in the slurry, and the organic acid iron is adsorbed in the microspheres, which can chelate with the water-soluble phosphorus, fluorine and residual heavy metal ions in the phosphogypsum, and the trivalent iron ions and phosphates are flocculated and precipitated. At the same time, in a weakly alkaline environment, the calcium ions in lime, saw mud, sludge and cement will also be complexed with phosphates to form calcium phosphates. These calcium phosphates will gradually be adsorbed and deposited on the starch microspheres, and will also form active hydroxy calcium phosphates in an alkaline environment, and then chemically adsorb with fluoride ions, greatly reducing the content of free fluorine and phosphorus ions in the slurry.

[0011] In addition, the intermediate material after regeneration is first calcined at low temperature, at which time the starch microspheres will be carbonized and a large amount of gas will be generated. These gases will form a microporous structure in the microspheres, and under high temperature conditions, the fluorine and phosphorus deposits formed will be adsorbed and fixed in these microporous structures, which can effectively inhibit the segregation of fluorine and phosphorus ions. In addition, after low-temperature calcination and then high-temperature calcination, on the one hand, the micro-particle components in the slurry will have a certain blocking effect on the micropores, and on the other hand, the surface of the microspheres will undergo melt crystallization under high temperature conditions, thereby blocking the fluorine and phosphorus substances in the microspheres, greatly reducing the amount of secondary segregation release during subsequent use.

[0012] Preferably, the organic acid iron is at least one of ferric citrate, ferric tartrate, ferric acetate and ferric malate.

[0013] By adopting the above technical solution, optimizing and adjusting the types of organic acid iron, the molecules of ferric citrate, ferric tartarate, ferric acetate and ferric malate have more suitable steric hindrance and better chelation effect on phosphorus ions. In addition, in the subsequent calcination process, the organic acid radicals chelated by the organic acid iron can also be decomposed, increasing the specific surface area of ​​the microspheres and enhancing the adsorption capacity.

[0014] Preferably, the organic acid iron consists of ferric citrate and ferric acetate in a molar ratio of (3.5-5):(1-2).

[0015] By adopting the above technical solution, the composition ratio of organic acid iron is further tested and optimized, the molecular activity of organic acid radicals is improved, and the anchoring ability to phosphorus ions is enhanced.

[0016] Preferably, the starch is one of carboxymethyl starch, hydroxyethyl starch and amino starch.

[0017] By adopting the above technical solution, the types of starch are optimized and adjusted. Carboxymethyl starch, hydroxyethyl starch and amino starch have a large number of polar groups, and have stronger adsorption performance for fluorine and phosphorus precipitates. And as the number of polar groups in the microspheres increases, the reaction between organic acid iron and phosphorus ions is also promoted, and the removal rate of phosphorus ions is higher.

[0018] Preferably, the mass ratio of the phosphogypsum to the chelating agent is (8-11):1.

[0019] By adopting the above technical solution, the ratio of phosphogypsum to chelating agent is optimized and adjusted, and the proportion of microspheres in the slurry is balanced, so that the adsorption process and chelating reaction proceed in an orderly and smooth manner, and the probability of invalid adsorption phenomena such as semi-adsorbed microspheres or semi-enclosed microspheres is reduced.

[0020] Preferably, the raw material also includes 1-1.5 parts by weight of urea.

[0021] By adopting the above technical solution, the addition of urea can further improve the surface state of the microporous structure in the microspheres, increase the number of polar groups, and thus enhance the fixation ability of the microsphere structure to fluorine and phosphorus precipitates.

[0022] In the second aspect, the present application provides a regeneration process of solid-state synergistic recycled materials of phosphogypsum, saw mud and sludge, which adopts the following technical solution:

[0023] A regeneration process of solid-state synergistic regenerated materials of phosphogypsum, sawdust and sludge comprises the following steps:

[0024] S1: crush and grind phosphogypsum, sawdust and sewage sludge for later use;

[0025] S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water to obtain a slurry, then add a chelating agent and heat to 60-80°C, stir continuously, regenerate and dry to obtain an intermediate material;

[0026] S3: The intermediate material is calcined at low temperature and high temperature to obtain the product.

[0027] By adopting the above technical scheme, after phosphogypsum, saw mud and sludge are crushed and ground, the particle size of solid particles is reduced, the dissolution of harmful substances in phosphogypsum is promoted, and the adsorption capacity of saw mud and sludge on harmful substances is also improved. Then the components are mixed with water to form a slurry, and lime, cement, calcium citrate, aluminum sulfate and chelating agent are used to remove water-soluble fluorine and phosphorus ions, and then calcined at low temperature and high temperature to form a microsphere adsorbent, which adsorbs and fixes the precipitated fluorine and phosphorus, which can effectively inhibit the reverse release and segregation of fluorine and phosphorus and reduce secondary pollution.

[0028] Preferably, in step S3, the temperature of low-temperature calcination is 200-260° C., and the calcination time is 1-1.5 h; the temperature of high-temperature calcination is 380-450° C., and the calcination time is 30-45 min.

[0029] By adopting the above technical solution, the starch is first calcined at a relatively low temperature, so that the starch can be fully carbonized and a uniform microporous structure is formed, thereby obtaining a large specific surface area, which has a good adsorption and fixation effect on fluorine and phosphorus. Then, the microspheres are calcined at a relatively high temperature, so that the surface of the microspheres is crystallized and closed in time, thereby reducing the amount of reverse migration of fluorine and phosphorus.

[0030] Preferably, the step S1 further comprises the step of adding urea.

[0031] On the third aspect, the present application provides an application of phosphogypsum, sawdust and sludge solid co-recycled materials for soil remediation, bridge construction and road construction.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. Since the present application adopts the co-regeneration of phosphogypsum, saw mud and sludge, the harmful components such as residual acid and heavy metals in the phosphogypsum are removed, and under the joint action of lime, cement, calcium citrate and aluminum sulfate as chelating agents, the content of water-soluble fluorine and phosphorus is greatly reduced, and the secondary segregation of fluorine and phosphorus is also reduced.

[0034] 2. In the present application, different organic acid irons are preferably used in combination, which has a good chelating and adsorption effect on phosphorus ions, and also promotes the co-precipitation reaction of phosphorus-containing salts and fluoride ions, greatly improving the removal rate of fluorine and phosphorus.

[0035] 3. The phosphogypsum, saw mud and sludge solid co-regenerated materials prepared by the regeneration process of the present application have lower free fluorine and phosphorus, and are not prone to secondary segregation and do not produce secondary pollution. DETAILED DESCRIPTION

[0036] The present application is further described in detail below with reference to the embodiments.

[0037] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.

[0038] Example

[0039] Example 1

[0040] The solid synergistic recycled material of phosphogypsum, saw mud and sewage sludge in this embodiment is made of the following raw materials: 150 kg of phosphogypsum, 50 kg of saw mud, 30 kg of sewage sludge, 10 kg of lime, 2 kg of cement, 2 kg of calcium citrate, 0.5 kg of aluminum sulfate and 7 kg of chelating agent. The chelating agent is composed of starch and organic acid iron in a mass ratio of 8:15.

[0041] The sawdust is stone sawdust, the sewage sludge is urban and rural sewage sludge, the starch is corn starch, and the organic acid iron is iron succinate.

[0042] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment includes the following steps:

[0043] S1: Put phosphogypsum, sawdust and sludge into the sorting machine to screen out plastic, metal and other debris, and then crush and grind them for use;

[0044] S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water in a mixer at a stirring speed of 80 rpm / min to obtain a slurry, then put it into a high-temperature kiln, add a chelating agent and heat it to 80°C, stir it continuously, regenerate it, and dry it to obtain an intermediate material;

[0045] S3: The intermediate material is heated to 200°C for low-temperature calcination for 1.5 hours, then heated to 500°C, and calcined at high temperature for 20 minutes under nitrogen protection to obtain the product.

[0046] The application of phosphogypsum, sawdust and sludge solid co-regeneration materials in this embodiment can be used as base materials in soil treatment; it can also be used as a mixture in bridge, road and building construction, and is not easy to cause secondary pollution.

[0047] Example 2

[0048] The solid synergistic recycled material of phosphogypsum, saw mud and sewage sludge in this embodiment is made of the following raw materials: 120kg of phosphogypsum, 65kg of saw mud, 20kg of sewage sludge, 15kg of lime, 3.5kg of cement, 1kg of calcium citrate, 1kg of aluminum sulfate, and 10kg of chelating agent. The chelating agent is composed of starch and organic acid iron in a mass ratio of 8:15.

[0049] The sawdust is stone sawdust, the sewage sludge is urban and rural sewage sludge, the starch is carboxymethyl starch, and the organic acid iron is iron formate.

[0050] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment includes the following steps:

[0051] S1: Put phosphogypsum, sawdust and sludge into the sorting machine to screen out plastic, metal and other debris, and then crush and grind them for use;

[0052] S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water in a mixer at a stirring speed of 50 rpm / min to obtain a slurry, then put it into a high-temperature kiln, add a chelating agent and heat it to 60°C, stir it continuously, regenerate it, and dry it to obtain an intermediate material;

[0053] S3: The intermediate material is heated to 200°C for low-temperature calcination for 1.5 hours, then heated to 500°C, and calcined at high temperature for 20 minutes under nitrogen protection to obtain the product.

[0054] The application of phosphogypsum, sawdust and sludge solid co-regeneration materials in this embodiment can be used as base materials in soil treatment; it can also be used as a mixture in bridge, road and building construction, and is not easy to cause secondary pollution.

[0055] Example 3

[0056] The solid synergistic recycled material of phosphogypsum, saw mud and sewage sludge in this embodiment is made of the following raw materials: 135 kg of phosphogypsum, 60 kg of saw mud, 28 kg of sewage sludge, 12 kg of lime, 3.2 kg of cement, 1.5 kg of calcium citrate, 0.85 kg of aluminum sulfate, and 9 kg of chelating agent. The chelating agent is composed of starch and organic acid iron in a mass ratio of 8:15.

[0057] The saw mud is stone saw mud. The sewage sludge is urban and rural sewage sludge. The starch is composed of hydroxyethyl starch and amino starch in a mass ratio of 1:2. The organic acid iron is iron formate.

[0058] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment includes the following steps:

[0059] S1: Put phosphogypsum, sawdust and sludge into the sorting machine to screen out plastic, metal and other debris, and then crush and grind them for use;

[0060] S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water in a mixer at a stirring speed of 100 rpm / min to obtain a slurry, then put it into a high-temperature kiln, add a chelating agent and heat it to 72°C, stir it continuously, regenerate it, and dry it to obtain an intermediate material;

[0061] S3: The intermediate material is heated to 200°C for low-temperature calcination for 1.5 hours, then heated to 500°C, and calcined at high temperature for 20 minutes under nitrogen protection to obtain the product.

[0062] The application of phosphogypsum, sawdust and sludge solid co-regeneration materials in this embodiment can be used as base materials in soil treatment; it can also be used as a mixture in bridge, road and building construction, and is not easy to cause secondary pollution.

[0063] Example 4

[0064] The phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment is different from that of Example 3 in that: in the raw materials, the chelating agent is composed of starch and organic acid iron in a mass ratio of 5:20, and the rest is the same as in Example 3.

[0065] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 3.

[0066] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 3.

[0067] Example 5

[0068] The phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment is different from that of Example 3 in that: in the raw materials, the chelating agent is composed of starch and organic acid iron in a mass ratio of 6:18.5, and the rest is the same as in Example 3.

[0069] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 3.

[0070] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 3.

[0071] Example 6

[0072] The phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment is different from that of Example 5 in that the organic acid iron in the raw materials is tartaric acid iron, and the rest is the same as that in Example 5.

[0073] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 5.

[0074] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 5.

[0075] Example 7

[0076] The phosphogypsum, saw mud and sludge solid co-regeneration materials of this embodiment are different from those of Example 5 in that in the raw materials, the organic acid iron is composed of ferrous acetate and ferrous malate in a molar ratio of 2:1, and the rest is the same as in Example 5.

[0077] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 5.

[0078] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 5.

[0079] Example 8

[0080] The difference between the phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment and that in Example 5 is that in the raw materials, the organic acid iron is composed of ferric citrate and ferric acetate in a molar ratio of 3.5:2, and the rest is the same as in Example 5.

[0081] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 5.

[0082] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 5.

[0083] Example 9

[0084] The phosphogypsum, saw mud and sludge solid co-regeneration material of this embodiment is different from that of Example 5 in that: in the raw materials, the organic acid iron is composed of ferric citrate and ferric acetate in a molar ratio of 5:1, and the rest is the same as in Example 5.

[0085] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 5.

[0086] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 5.

[0087] Example 10

[0088] The phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment are different from those in Example 8 in that the raw materials also include 1.2 kg of urea, and the rest are the same as in Example 8.

[0089] The regeneration process of phosphogypsum, saw mud and sludge solid co-regenerated materials in this embodiment is the same as that in Example 8.

[0090] The application of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 8.

[0091] Embodiment 11

[0092] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is different from that in Example 10 in that: in step S3, the temperature of low-temperature calcination is 260°C, and the calcination time is 1 hour; the temperature of high-temperature calcination is 380°C, and the calcination time is 45 minutes.

[0093] The raw material composition of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 10.

[0094] The application of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 10.

[0095] Example 12

[0096] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is different from that in Example 10 in that: in step S3, the temperature of low-temperature calcination is 200°C, and the calcination time is 1.5h; the temperature of high-temperature calcination is 450°C, and the calcination time is 30min.

[0097] The raw material composition of phosphogypsum, saw mud and sludge solid co-regeneration material in this embodiment is the same as that in Example 10.

[0098] The application of phosphogypsum, saw mud and sludge solid co-regeneration materials in this embodiment is the same as that in Example 10.

[0099] Comparative Example

[0100] Comparative Example 1

[0101] The solid synergistic recycled materials of phosphogypsum, sawdust and sewage sludge in this comparative example are made of the following raw materials: 150 kg of phosphogypsum and 7 kg of chelating agent. The chelating agent is composed of starch and organic acid iron in a mass ratio of 8:15.

[0102] Wherein, the organic acid iron is iron succinate.

[0103] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example comprises the following steps:

[0104] S1: Put the phosphogypsum into the sorting machine to screen out plastic, metal and other debris, and then crush and grind it for standby use;

[0105] S2: Mix the formulated amount of phosphogypsum, chelating agent and water in a mixer at a stirring speed of 80 rpm / min to obtain a slurry, and then put it into a high-temperature kiln and heat it to 80°C, continuously stir, regenerate and dry to obtain an intermediate material;

[0106] S3: The intermediate material is heated to 200°C for low-temperature calcination for 1.5 hours, then heated to 500°C, and calcined at high temperature for 20 minutes under nitrogen protection to obtain the product.

[0107] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0108] Comparative Example 2

[0109] The phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is made of the following raw materials by weight: 150 kg of phosphogypsum, 50 kg of saw mud, 30 kg of sludge, 10 kg of lime, 2 kg of cement, 2 kg of calcium citrate and 0.5 kg of aluminum sulfate.

[0110] Among them, sawdust is stone sawdust, and sewage sludge is urban and rural sewage sludge.

[0111] The regeneration process of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example comprises the following steps:

[0112] S1: Put phosphogypsum, sawdust and sludge into the sorting machine to screen out plastic, metal and other debris, and then crush and grind them for use;

[0113] S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water in a mixer at a stirring speed of 80 rpm / min to obtain a slurry, and then put it into a high-temperature kiln and heat it to 80°C, continuously stir, regenerate and dry to obtain an intermediate material;

[0114] S3: The intermediate material is heated to 200°C for low-temperature calcination for 1.5 hours, then heated to 500°C, and calcined at high temperature for 20 minutes under nitrogen protection to obtain the product.

[0115] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0116] Comparative Example 3

[0117] The phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example are different from those in Example 1 in that: in the raw materials, the chelating agent is composed of starch and organic acid iron in a mass ratio of 15:8, and the rest is the same as in Example 1.

[0118] The regeneration process of the phosphogypsum, saw mud and sludge solid co-regenerated materials in this comparative example is the same as that in Example 1.

[0119] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0120] Comparative Example 4

[0121] The phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example are different from those in Example 1 in that the chelating agent in the raw materials is starch, and the rest is the same as in Example 1.

[0122] The regeneration process of the phosphogypsum, saw mud and sludge solid co-regenerated materials in this comparative example is the same as that in Example 1.

[0123] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0124] Comparative Example 5

[0125] The phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example are different from those in Example 1 in that the chelating agent in the raw materials is organic acid iron, and the rest is the same as in Example 1.

[0126] The regeneration process of the phosphogypsum, saw mud and sludge solid co-regenerated materials in this comparative example is the same as that in Example 1.

[0127] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0128] Comparative Example 6

[0129] The phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example are different from those in Example 1 in that: in the raw materials, the chelating agent is composed of starch and ferric chloride in a mass ratio of 8:15, and the rest is the same as in Example 1.

[0130] The regeneration process of the phosphogypsum, saw mud and sludge solid co-regenerated materials in this comparative example is the same as that in Example 1.

[0131] The application of phosphogypsum, saw mud and sludge solid co-regeneration material in this comparative example is the same as that in Example 1.

[0132] Performance testing

[0133] Detection Methods

[0134] The phosphogypsum, saw mud and sludge solid co-regeneration materials of Examples 1-12 and Comparative Examples 1-6 were tested for soluble phosphorus and fluorine contents according to the national standard GB / T23456-2018 "Phosphogypsum". Among them, the soluble phosphorus content in the phosphogypsum raw material of this embodiment was 0.32%, and the soluble fluorine was 0.5%. The relevant test results are shown in Table 1.

[0135] Table 1 Performance test data of phosphogypsum, saw mud and sludge solid synergistic recycled materials of Examples 1-12 and Comparative Examples 1-6

[0136] Serial number Soluble fluoride (%) Soluble phosphorus (%) Example 1 0.062 0.075 Example 2 0.060 0.072 Example 3 0.055 0.070 Example 4 0.057 0.071 Example 5 0.051 0.066 Example 6 0.049 0.063 Example 7 0.042 0.053 Example 8 0.033 0.046 Example 9 0.040 0.057 Example 10 0.030 0.043 Embodiment 11 0.028 0.040 Example 12 0.025 0.039 Comparative Example 1 0.17 0.19 Comparative Example 2 0.28 0.35 Comparative Example 3 0.95 0.116 Comparative Example 4 0.15 0.165 Comparative Example 5 0.118 0.122 Comparative Example 6 0.135 0.14

[0137] It can be seen from the analysis of Examples 1-3 and Comparative Examples 1-2 in combination with Table 1 that the use of saw mud and sludge can be used to perform basic adsorption on harmful components in phosphogypsum, reducing the amount of chelating agent used. In addition, lime, cement, calcium citrate, and aluminum sulfate are used in conjunction with chelating agents to remove water-soluble fluorine and phosphorus ions. At the same time, a special low-temperature and high-temperature calcination process is used, which can greatly reduce the secondary dissolution of fluorine and phosphorus and reduce the amount of secondary pollution. It can be seen that the soluble fluorine in Example 3 is reduced to 0.055%, and the soluble phosphorus is reduced to 0.070%. In addition, only a chelating agent is used in Comparative Example 1, and fluorine and phosphorus cannot be effectively removed as a whole. In Comparative Example 2, no composite components such as saw mud and sludge are used, resulting in easy secondary separation of soluble phosphorus and fluorine.

[0138] From the analysis of Examples 4-5 and Comparative Example 3 in combination with Table 1, it can be seen that the ratio of starch to organic acid iron is optimized and adjusted, the adsorption performance and fixation performance of the microsphere adsorbent are balanced, the solidification ability of phosphorus and fluoride ions is further enhanced, and the secondary precipitation amount is reduced. From the analysis of Examples 6-7 and Examples 8-9 in combination with Table 1, it can be seen that the type composition of organic acid iron is further tested and adjusted, and organic acid iron with suitable steric hindrance is screened to inhibit the reverse release of fluorine and phosphorus elements and reduce the secondary release of fluorine and phosphorus.

[0139] By analyzing Example 10 and Examples 11-12 and combining with Table 1, it can be seen that the addition of urea can increase the number of polar groups in the microspheres, promoting the positive adsorption reaction and fixation process. At the same time, the calcination process is optimized to improve the pore structure in the adsorption microspheres, further improving the solidification ability of phosphorus and fluorine. It can be seen that the soluble fluorine in Example 12 is reduced to 0.025%, and the soluble phosphorus content is reduced to 0.039%, and secondary segregation is not easy to occur.

[0140] It can be seen from the analysis of Examples 1-12 and Comparative Examples 4-6 in combination with Table 1 that when only starch is used as a chelating agent, although a microsphere adsorbent can be formed, a certain amount of fluorine and phosphorus ions can be adsorbed in the early stage, but the curing effect in the later stage is poor, and secondary segregation is prone to occur. When only organic acid iron is used as a chelating agent, although the binding force with fluorine and phosphorus is good, effective closure cannot be obtained in subsequent use, and secondary release phenomenon is still prone to occur after contact with an external medium. And it is found by comparison that organic acid iron has a stronger chelating fixation performance than inorganic acid iron, and effectively reduces the content of fluorine and phosphorus.

[0141] On the whole, the application adopts saw mud, sludge, lime and other components in combination with a chelating agent, which can not only reduce the content of fluorine and phosphorus ions, but also has a good solidification effect on fluorine and phosphorus ions, greatly reducing the amount of secondary segregation. The recycled material has good product quality, is environmentally friendly and harmless, and is suitable for wide promotion and application.

[0142] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A solid synergistic recycled material of phosphogypsum, sawdust and sewage sludge, characterized in that: The invention is mainly made of the following raw materials in parts by weight: 120-150 parts of phosphogypsum, 50-65 parts of saw mud, 20-30 parts of sludge, 10-15 parts of lime, 2-3.5 parts of cement, 1-2 parts of calcium citrate, 0.5-1 parts of aluminum sulfate, and 7-10 parts of chelating agent; the chelating agent is composed of starch and organic acid iron in a mass ratio of (5-8):(15-20); the organic acid iron is at least one of ferric citrate, ferric tartaric acid, ferric acetate, and ferric malate; the regeneration process of the phosphogypsum, saw mud and sludge solid-state synergistic regeneration material comprises the following steps: S1: crush and grind phosphogypsum, sawdust and sewage sludge for later use; S2: Mix the formulated amount of phosphogypsum, saw mud, sludge, lime, cement, calcium citrate, aluminum sulfate and water to obtain a slurry, then add a chelating agent and heat to 60-80°C, stir continuously, regenerate and dry to obtain an intermediate material; S3: The intermediate material is subjected to low-temperature calcination and high-temperature calcination to obtain the product. The temperature of the low-temperature calcination is 200-260° C., and the calcination time is 1-1.5 hours; the temperature of the high-temperature calcination is 380-450° C., and the calcination time is 30-45 minutes.

2. The solid-state synergistic recycled material of phosphogypsum, saw mud and sewage sludge according to claim 1, characterized in that: The organic acid iron is composed of ferric citrate and ferric acetate in a molar ratio of (3.5-5):(1-2).

3. The solid-state synergistic recycled material of phosphogypsum, saw mud and sewage sludge according to claim 1, characterized in that: The starch is at least one of carboxymethyl starch, hydroxyethyl starch and amino starch.

4. The solid-state synergistic recycled material of phosphogypsum, sawdust and sewage sludge according to claim 1, characterized in that: The mass ratio of the phosphogypsum to the chelating agent is (8-11):

1.

5. The solid-state synergistic recycled material of phosphogypsum, saw mud and sewage sludge according to claim 1, characterized in that: The raw materials also include 1-1.5 parts by weight of urea, and step S1 also includes a step of adding urea.

6. An application of phosphogypsum, saw mud and sludge solid co-regeneration material as claimed in claim 1, characterized in that: Used for soil treatment, bridge construction and road construction.