Fouled material treatment method

Abstract

A fouled material treatment method. The method comprises: using sulfuric acid to carry out first leaching treatment on a fouled device to be treated; and using mixed acid to carry out second leaching treatment on the fouled device that has been subjected to the first leaching treatment, wherein the mixed acid comprises phosphoric acid and other acids, and the other acids do not contain any one of hydrochloric acid, nitric acid, oxalic acid, and hydrofluoric acid. The method consumes a short time, has a good fouled material removal effect and low cost, would not cause serious corrosion to devices, can implement recycling of leachates, and can be widely used for the cleaning of fouled materials in different devices.

Description

A method for treating scaling materials Technical Field

[0001] The present disclosure relates to the technical field of scaling treatment, and in particular to a method for treating scaling materials. Background Art

[0002] Iron phosphate, the precursor material for lithium iron phosphate batteries, determines 99% of its performance. Its quality is determined by many factors, including the process and the amount of impurities introduced. Its quality and price fundamentally impact its performance and cost. Iron phosphate costs are comprised of material, manufacturing, and labor costs, with manufacturing accounting for approximately 20% of the total. During the iron phosphate production process, due to the high phosphate concentration, some soluble and insoluble impurities deposit on the inner walls of reactors, pipelines, and other equipment, forming a scale layer. Currently, reactor scale is categorized into two types, depending on their adhesion to the reactor wall. Phosphate scale in the unheated area is relatively soft and accumulates on the outer layer. The closer to the reactor wall, the more severe the heat builds, and the scale becomes hard and difficult to remove. After a long period of reaction, the scale layer becomes thicker and thicker, which will eventually lead to the following problems: ① The scale layer in the reactor is too thick, the heat exchange efficiency is reduced, and the accuracy of the temperature feedback system is affected. In order to reach the set temperature, more energy is consumed, and the reaction time needs to be increased, and the production efficiency is reduced; ② During the reaction process, as the reaction time increases, the scale layer deteriorates and becomes abnormally hard. Part of the scale layer falls off and is introduced into the product, affecting product quality; ③ The residual material from the previous batch sticks to the scale layer, resulting in poor consistency between batches, which will eventually affect the quality of the product. Therefore, the scaling materials in the production process will have multiple impacts on product cost and quality.

[0003] Currently, there are three main ways to deal with scaled materials in reactors during actual production: ① Manual cleaning, which is low-cost and labor-intensive, but also has low cleaning efficiency and high safety risks; ② Chemical cleaning, which mainly uses high-concentration phosphoric acid, nitric acid, hydrochloric acid, and oxalic acid for cleaning, which not only increases processing costs, but also some acid solutions will inevitably cause corrosion to equipment or produce toxic gases; ③ High-pressure water cleaning, which is prone to incomplete cleaning.

[0004] In view of this, the present disclosure is proposed.

[0005] Summary of the Invention

[0006] The purpose of the present disclosure is to provide a method for treating scaling materials to improve or solve the above technical problems.

[0007] In a first aspect, the present disclosure provides a method for treating a scaling material, comprising the following steps: performing a first leaching treatment on a scaling device to be treated with dilute sulfuric acid, and performing a second leaching treatment on the scaling device that has undergone the first leaching treatment with a mixed acid;

[0008] The mixed acid includes phosphoric acid and other acids, and the other acids do not include any of hydrochloric acid, nitric acid, oxalic acid and hydrofluoric acid.

[0009] In an optional embodiment, the first leaching process includes at least one of the following features:

[0010] Feature 1: The temperature of the first leaching treatment is 60℃-80℃;

[0011] Feature 2: The first leaching treatment time is 30min-120min;

[0012] Feature 3: The concentration of dilute sulfuric acid used in the first leaching treatment is 1.0mol / L-3.0mol / L;

[0013] Feature 4: The volume of dilute sulfuric acid used in the first leaching treatment is not less than 80% of the volume of the scaling device;

[0014] Feature 5: The first leaching treatment is carried out under stirring conditions.

[0015] In an optional embodiment, the temperature of the first leaching treatment is 70° C.-80° C.; and / or the concentration of the dilute sulfuric acid used in the first leaching treatment is 1.0 mol / L-2.5 mol / L.

[0016] In an optional embodiment, the second leaching process includes at least one of the following features:

[0017] Feature 1: The temperature of the second leaching treatment is 60℃-95℃;

[0018] Feature 2: The molar concentration ratio of phosphoric acid to other acids is (1:1)-(1:4);

[0019] Feature 3: The concentration of phosphoric acid in the mixed acid used in the second leaching treatment is 0.3 mol / L-1.0 mol / L;

[0020] Feature 4: The other acid used in the second leaching treatment includes at least one of malic acid, citric acid and sulfuric acid.

[0021] In an optional embodiment, the molar concentration ratio of phosphoric acid to other acids is (1:2)-(1:3).

[0022] In an alternative embodiment, the mixed acid used in the second leaching treatment contains phosphoric acid and sulfuric acid.

[0023] In an optional embodiment, an oxidant and a corrosion inhibitor are also used during the second leaching process.

[0024] In an optional embodiment, the molar concentration ratio of phosphoric acid to the oxidant is (1:0.1)-(1:0.5), and / or the molar concentration ratio of phosphoric acid to the oxidant is (1:0.02)-(1:0.10).

[0025] In an optional embodiment, the molar concentration ratio of phosphoric acid to the oxidant is (1:0.2)-(1:0.3), and / or the molar concentration ratio of phosphoric acid to the corrosion inhibitor is (1:0.03)-(1:0.05).

[0026] In an optional embodiment, the oxidant includes hydrogen peroxide; and / or the corrosion inhibitor includes at least one of hexamethylenetetramine, Lan-826 and dimethylthiourea.

[0027] In an optional embodiment, the second leaching treatment includes: first soaking the scaling device after the first leaching treatment with a mixed acid, and then adding an oxidant and a corrosion inhibitor to continue soaking.

[0028] In an optional embodiment, the scaling device is immersed in the mixed acid for 30 min to 120 min; and / or the immersion time after the oxidant and the corrosion inhibitor are added is 60 min to 240 min.

[0029] In an alternative embodiment, the oxidant and the corrosion inhibitor are added to the mixed acid under stirring.

[0030] In an optional embodiment, before the first leaching treatment, the method further includes: flushing the scaling device to be treated.

[0031] In an optional embodiment, flushing is performed under a water pressure of 15 MPa-20 MPa.

[0032] In an optional embodiment, the descaling device obtained after the second leaching treatment is passivated.

[0033] In an alternative embodiment, the reagent used for the passivation treatment includes a passivating agent.

[0034] In an optional embodiment, the passivating agent includes at least one of sodium hydroxide, sodium carbonate, trisodium phosphate, sodium hexametaphosphate, and sodium tripolyphosphate.

[0035] In an alternative embodiment, the concentration of the passivating agent is 0.1%-0.7%.

[0036] In an optional embodiment, the reagent used for the passivation treatment further includes a surfactant.

[0037] In an alternative embodiment, the surfactant includes at least one of sodium lauryl sulfate, sodium dodecylbenzene sulfonate, polyethylene glycol 400, and lauric acid.

[0038] In an alternative embodiment, the concentration of the surfactant is 0.05% to 0.3%.

[0039] In an optional embodiment, the temperature of the passivation treatment is 40° C.-70° C.; and / or the time of the passivation treatment is 30 min-180 min.

[0040] In an optional embodiment, the descaling device after the passivation treatment is subjected to a water washing treatment.

[0041] In an optional embodiment, the water washing time is 10 min-30 min, and / or the water washing is performed until the conductivity of the washing liquid obtained by washing is less than 500 μm / cm.

[0042] In an optional embodiment, the primary leachate obtained from the first leaching treatment and / or the secondary leachate obtained from the second leaching treatment are recycled.

[0043] In an optional embodiment, the primary leachate and / or the secondary leachate is used to prepare the reaction metal solution used for synthesizing ferric phosphate.

[0044] In an alternative embodiment, the scaling device comprises an iron phosphate production unit, a filter press, or a pipeline.

[0045] In an optional embodiment, the ferric phosphate production device is a reactor for producing ferric phosphate.

[0046] In an optional embodiment, the material of the reactor includes enamel, polytetrafluoroethylene or stainless steel.

[0047] The present invention utilizes a two-step leaching process to remove scaling material from a scaling device, effectively removing scaling material with high efficiency and effectiveness. Each leaching process avoids the use of chemical reagents such as nitric acid, hydrochloric acid, and oxalic acid, thereby avoiding and reducing potential corrosion to equipment caused by these acidic substances, resulting in a safer process. Furthermore, the majority of the acid used in each leaching process is low-value, low-concentration acid, which is inexpensive and helps reduce processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0049] FIG1 is a photograph of the inner wall of the reactor before the first leaching treatment in Example 1;

[0050] FIG2 is a photograph of the inner wall of the reactor after the first leaching treatment in Example 1;

[0051] FIG3 is a photograph of the inner wall of the reactor after the second leaching treatment in Example 1;

[0052] FIG4 is a photograph of the inner wall of the reactor corresponding to the second leaching treatment in Comparative Example 1;

[0053] FIG5 is a photograph of the inner wall of the reactor corresponding to the second leaching treatment in Comparative Example 2;

[0054] FIG6 is a photograph of the inner wall of the reactor corresponding to the second leaching treatment in Comparative Example 3. DETAILED DESCRIPTION

[0055] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure are described clearly and completely below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer were followed. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0056] The following is a detailed description of the method for treating scaling materials provided by the present disclosure.

[0057] The present disclosure provides a method for treating scaling materials, which may include the following steps: performing a first leaching treatment on a scaling device to be treated with dilute sulfuric acid, and performing a second leaching treatment on the scaling device that has undergone the first leaching treatment with a mixed acid.

[0058] The scaling device may be, for example, an iron phosphate production device (a reactor for producing iron phosphate), and the material of the iron phosphate production device may, for example but not limited to, include enamel, polytetrafluoroethylene, or stainless steel. In addition, the scaling device in the present disclosure may also be other devices that are subject to scaling, such as a filter press or a pipeline.

[0059] It should be noted that, taking the scaling device as an iron phosphate reactor as an example, according to the contact distance between the iron phosphate scaling material and the inner wall of the reactor and / or the surface of the stirring paddle in the reactor, the morphology and properties of the iron phosphate scaling material at different contact distances are different. The iron phosphate scaling material in direct contact with the inner wall of the reactor and / or the surface of the stirring paddle in the reactor is in the form of a hard lump and has extremely strong adhesion; the iron phosphate scaling material slightly away from the inner wall of the reactor and / or the surface of the stirring paddle in the reactor is softer and has slightly stronger adhesion than the iron phosphate scaling material in direct contact with the inner wall of the reactor and / or the surface of the stirring paddle in the reactor; and in the direction away from the inner wall of the reactor and / or the surface of the stirring paddle in the reactor, the outermost iron phosphate scaling material will be softer and have weaker adhesion.

[0060] In some embodiments, the scaling device to be treated may be flushed before the first leaching treatment. For example, the inner wall of the scaling device may be flushed with a high-pressure water gun to flush out materials with relatively weak adhesion in the scaling device.

[0061] Illustratively, flushing may be performed under a water pressure of 15-20 MPa (such as 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa or 20 MPa, etc.).

[0062] In the present disclosure, the temperature of the first leaching treatment may be 60° C.-80° C., such as 60° C., 65° C., 70° C., 75° C., or 80° C., or any other value within the range of 60° C.-80° C. In some embodiments, the temperature of the first leaching treatment is 70° C.-80° C., under which temperature conditions better leaching effects may be achieved.

[0063] The time of the first leaching treatment can be 30 min-120 min, such as 30 min, 50 min, 80 min, 100 min or 120 min, or any other value within the range of 30 min-120 min.

[0064] If the temperature of the first leaching treatment is too low or the time is too short, it is not conducive to the shedding of the outer layer of scale. The scale layer of the residual material after the first leaching is thicker, and more scaling materials need to be dissolved in the second leaching. The secondary leachate is more likely to reach saturation, which is not conducive to the reuse of the secondary leachate. If the temperature of the first leaching treatment is too high or the time is too long, it is not conducive to reducing energy consumption and time costs.

[0065] In the present disclosure, the concentration of the dilute sulfuric acid used for the first leaching treatment can be 1.0mol / L-3.0mol / L, such as 1.0mol / L, 1.5mol / L, 2.0mol / L, 2.5mol / L or 3.0mol / L, or any other value within the range of 1.0mol / L-3.0mol / L. In some embodiments, the concentration of the dilute sulfuric acid used for the first leaching treatment is 1.0mol / L-2.5mol / L. During the specific operation, the volume of the dilute sulfuric acid can be set to not less than 80% of the volume of the scaling device, for example, 80%, 85%, 90% or 95% of the volume of the scaling device, so as to fully remove the scale at each position of the scaling device.

[0066] In some embodiments, the first leaching process can be performed under stirring conditions. For example, the stirring speed can be 5 m / s to 7 m / s. Performing the first leaching process under stirring conditions can improve the first leaching effect and shorten the first leaching time.

[0067] As mentioned above, by performing the first leaching on the scaling device, materials with slightly stronger adhesion can be removed from the scaling device compared to the flushing process. In other words, by the flushing and first leaching process, both materials with weaker adhesion and materials with slightly stronger adhesion can be removed from the scaling device.

[0068] It should be emphasized that if the scaling device is directly subjected to the first leaching treatment, it can also remove both weakly and slightly more strongly adhering materials within the scaling device. However, compared to the method of first rinsing and then the first leaching treatment, the Fe and P in the weakly and slightly more strongly adhering materials directly react with the sulfate ions in the dilute sulfuric acid, which easily causes the Fe and P in the primary leachate to reach saturation in a relatively short period of time. On the one hand, this is not conducive to the reuse of the primary leachate, and on the other hand, it will reduce the amount of dilute sulfuric acid that can continue to act, thereby greatly increasing the amount of dilute sulfuric acid required. In addition, the cost of dilute sulfuric acid is lower than that of phosphoric acid. Under the condition that dilute sulfuric acid can remove materials with slightly more adhesion, using dilute sulfuric acid as the acid solution for the first leaching treatment can greatly reduce the treatment cost of scaling materials.

[0069] In the present disclosure, the temperature of the second leaching treatment can be 60°C-95°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C, or any other value within the range of 60°C-95°C.

[0070] If the temperature of the second leaching treatment is too low, it will not be conducive to the dissolution and removal of the difficult-to-dissolve scale layer from the kettle wall, affecting the leaching effect. The chemical reaction rate is slow at low temperatures, and the sediment may not be easy to dissolve completely, resulting in the presence of residues. The cleaning process will take a long time to achieve a better cleaning effect.

[0071] If the temperature of the second leaching treatment is too high, it will not be conducive to reducing energy consumption costs. Excessively high temperature may cause the solution to evaporate, resulting in the scale layer cleaning effect near the liquid surface being less than expected.

[0072] The mixed acid used in the second leaching treatment includes phosphoric acid and other acids.

[0073] The concentration of phosphoric acid can be 0.3 mol / L-1.0 mol / L, such as 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L or 1.0 mol / L, or any other value within the range of 0.3 mol / L-1.0 mol / L.

[0074] The molar concentration ratio of phosphoric acid to the other acid can be (1:1)-(1:4), such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, or 1:4, or any other value within the range of (1:1)-(1:4). In some embodiments, the molar concentration ratio of phosphoric acid to the other acid is (1:2)-(1:3).

[0075] In the present disclosure, the aforementioned other acids do not include any of hydrochloric acid, nitric acid, oxalic acid, and hydrofluoric acid. This avoids the problems that may arise from using these acids in the prior art, such as: hydrochloric acid easily corrodes stainless steel equipment and produces hydrogen chloride gas; nitric acid decomposes and releases toxic nitrogen dioxide gas; oxalic acid wastewater treatment is expensive; and hydrofluoric acid is highly toxic and dangerous. For reference, the other acids used in the present disclosure may illustratively include at least one of malic acid, citric acid, and sulfuric acid.

[0076] In some embodiments, the mixed acid used in the second leaching treatment includes phosphoric acid and sulfuric acid.

[0077] Furthermore, during the second leaching process, an oxidant and a corrosion inhibitor may be used. The oxidant can increase the reaction rate between the scaling material and the mixed acid, and the corrosion inhibitor can slow down or reduce the corrosion of the scaling device caused by the mixed acid.

[0078] For reference, the scaling device after the first leaching treatment can be soaked with mixed acid first, and then the oxidant and corrosion inhibitor are added to continue soaking. In some embodiments, the oxidant and corrosion inhibitor can be added to the mixed acid in a stirred state.

[0079] The temperature for soaking the scaling device in the mixed acid can be 60° C. to 90° C., such as 60° C., 65° C., 70° C., 75° C., 80° C., 85° C., or 90° C. The soaking time for the scaling device in the mixed acid can be 30 min to 120 min, such as 30 min, 50 min, 80 min, 100 min, or 120 min. The soaking time after adding the oxidant and the corrosion inhibitor can be 60 min to 240 min, such as 60 min, 100 min, 140 min, 180 min, 220 min, or 240 min.

[0080] For reference, the oxidant may include, for example, hydrogen peroxide. The corrosion inhibitor may include, for example, at least one of hexamethylenetetramine, Lan-826, and dimethylthiourea.

[0081] The molar concentration ratio of the phosphoric acid to the oxidant can be (1:0.1)-(1:0.5), such as 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, or 1:0.5, or any other value within the range of (1:0.1)-(1:0.5). In some embodiments, the molar concentration ratio of the phosphoric acid to the oxidant is (1:0.2)-(1:0.3).

[0082] The molar concentration ratio of phosphoric acid to the corrosion inhibitor can be (1:0.02)-(1:0.10), such as 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.10, or any other value within the range of (1:0.02)-(1:0.10). In some embodiments, the molar concentration ratio of phosphoric acid to the corrosion inhibitor is (1:0.03)-(1:0.05).

[0083] By performing a second leaching treatment after the first leaching treatment, the highly adhesive materials adhering to the scaling device can be removed, making the scaling device a descaling device.

[0084] It should be emphasized that, under normal circumstances, the concentration of phosphoric acid needs to reach 25% or more to dissolve scaling materials. However, the method provided by the present disclosure can achieve a better descaling effect under the condition that the phosphoric acid concentration does not exceed 10%, greatly reducing the use of phosphoric acid and processing costs.

[0085] As mentioned above, the present disclosure adopts a two-step leaching method to remove scaling materials in a scaling device. Most of the acid used in the treatment process is low-value acid, which not only reduces the use of phosphoric acid and is low-cost, but also can effectively clean and achieve significant treatment effects.

[0086] In addition, it should be emphasized that if the scaling device is directly subjected to a second leaching treatment, it can also remove the materials with weak adhesion, slightly strong adhesion, and extremely strong adhesion in the scaling device. However, compared with the method of performing flushing, the first leaching treatment, and the second leaching treatment in sequence, the Fe and P in the materials with weak adhesion, slightly strong adhesion, and extremely strong adhesion directly react with the acid radical ions in the mixed acid, which easily causes the Fe and P in the secondary leachate to reach a saturated state in a shorter time. On the one hand, it is not conducive to the reuse of the secondary leachate, and on the other hand, it will reduce the amount of acid radical ions that can continue to act, thereby greatly increasing the required amount of mixed acid.

[0087] In some embodiments, the primary leachate obtained from the first leaching process and / or the secondary leachate obtained from the second leaching process may be recycled.

[0088] When the scaling device is a reactor for producing ferric phosphate, the primary leachate and / or the secondary leachate can be illustratively but not limitatively recycled to prepare the reaction metal liquid used for synthesizing ferric phosphate.

[0089] When the scaling device is other fouled device, the primary leachate and / or the secondary leachate can be recycled and utilized accordingly according to actual needs.

[0090] In order to protect the surfaces of the descaling device obtained after the second leaching treatment that are directly used for contacting the material, the descaling device can also be passivated.

[0091] For reference, the temperature of the passivation treatment may be 40° C.-70° C., such as 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., or 70° C. The time of the passivation treatment may be 30 min-180 min, such as 30 min, 50 min, 80 min, 100 min, 120 min, 150 min, or 180 min.

[0092] The reagents used for passivation treatment include passivating agents, which can be directly used to form a passivation film layer on the surfaces that come into contact with the material in the descaling device, thereby protecting the surface areas directly exposed inside the descaling device, reducing the rate of re-scaling during subsequent use, and extending the service life of the descaling device.

[0093] For reference, the passivating agent may illustratively but not limitatively include at least one of sodium hydroxide, sodium carbonate, trisodium phosphate, sodium hexametaphosphate, and sodium tripolyphosphate.

[0094] When in use, the passivator can be firstly mixed with water to form a passivator solution. The mass concentration of the passivator in the passivator solution can be 0.1%-0.7%, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or 0.7%, etc., or any other value within the range of 0.1%-0.7%.

[0095] In some embodiments, the reagent used in the passivation treatment may further include a surfactant, which can make the formed passivation film layer uniform and dense.

[0096] For reference, the surfactant may illustratively but not limitatively include at least one of sodium lauryl sulfate, sodium dodecylbenzenesulfonate, polyethylene glycol 400, and lauric acid.

[0097] When in use, the surfactant can be firstly mixed with water to form a surfactant solution. The mass concentration of the surfactant in the surfactant solution can be 0.05%-0.3%, such as 0.05%, 0.10%, 0.15%, 0.20%, 0.25% or 0.30%, etc., or any other value within the range of 0.05%-0.3%.

[0098] As mentioned above, the passivation treatment can provide good protection for the internal surface of the descaling device and improve the corrosion resistance of the descaling device.

[0099] It should be noted that in the present disclosure, the reagents used for the passivation treatment may also be added with other commonly used descaling agents as needed, which are not listed here one by one.

[0100] Furthermore, the descaling device after the passivation treatment can be washed with water to remove the residual passivating agent and avoid it affecting the subsequent use of the descaling device.

[0101] For reference, the water washing time may be 10 min to 30 min, such as 10 min, 15 min, 20 min, 25 min or 30 min, etc. In some embodiments, the water washing is performed until the conductivity of the washing liquid obtained by washing is less than 500 μm / cm.

[0102] The features and performance of the present disclosure are further described in detail below with reference to the embodiments.

[0103] Example 1

[0104] This embodiment provides a method for treating scaling materials in ferric phosphate production equipment (ferric phosphate reactor made of 2205 stainless steel), comprising the following steps:

[0105] S1: Rinse.

[0106] The inner wall and stirring paddle of the ferric phosphate reactor were rinsed with a high-pressure water gun. 500L of pure water was used at a water pressure of 20MPa for 5 minutes to remove materials with weak adhesion from the inner wall of the reactor and the surface of the stirring paddle.

[0107] S2: First leaching treatment.

[0108] After injecting 15130kg of pure water into the primary leachate tank, 1600kg of sulfuric acid was added under stirring (linear speed of 6.00m / s) to prepare 16m 3 , 1mol / L dilute sulfuric acid solution, the prepared dilute sulfuric acid solution is injected into 20m 3 In the reactor, the temperature was raised to 70°C and stirred for 100 minutes to leach out the scaling materials with slightly stronger adhesion.

[0109] The Fe and P concentrations in the leachate were tested every 20 minutes. At 80 and 100 minutes, the Fe and P concentrations increased from 3.45 g / L and 2.01 g / L at 80 minutes to 3.71 g / L and 2.11 g / L at 100 minutes, respectively. Leaching was stopped when the increase in Fe and P between tests was less than 0.3 g / L, and the primary leachate was recovered in the primary leachate storage tank.

[0110] S3: Second leaching treatment.

[0111] A mixed acid mixture of 922 kg of phosphoric acid (0.5 mol / L) and 1600 kg of sulfuric acid in a molar ratio of 1:2 was added to the secondary leaching tank. The mixed acid was injected into the reactor after the primary leaching treatment and allowed to soak at 70°C for 60 minutes. Stirring was then initiated (at a linear speed of 6.00 m / s), followed by the addition of 855 kg of hydrogen peroxide and 56 kg of hexamethylenetetramine. The temperature was raised to 90°C and leaching continued for 120 minutes to remove the highly adhesive scaling material. The molar ratios of phosphoric acid, sulfuric acid, hydrogen peroxide, and hexamethylenetetramine were 1:2:0.3:0.05, respectively.

[0112] At 100 and 120 minutes of leaching, the concentrations of Fe and P in the secondary leachate increased from 2.55 g / L and 14.49 g / L at 100 minutes to 2.58 g / L and 14.61 g / L at 120 minutes, respectively. After leaching, the secondary leachate was recovered to the secondary leachate storage tank.

[0113] S4: Passivation.

[0114] After the second leaching, 56 kg of sodium hydroxide and 16 kg of sodium dodecylbenzene sulfonate were added to water to form a passivation solution with a mass concentration of 0.5% sodium hydroxide and 0.2% sodium dodecylbenzene sulfonate. The passivation solution was then added to the reactor for passivation treatment at a temperature of 45° C. for 60 minutes.

[0115] S5: Wash with water.

[0116] After the passivation was completed, the reactor was rinsed with pure water for 10 min until the conductivity of the washing liquid was 431 μm / cm.

[0117] In this embodiment, the conditions of the inner wall of the reactor before the first leaching treatment, after the first leaching treatment, and after the second leaching treatment are shown in Figures 1, 2, and 3, respectively. As can be seen from Figure 1, after long-term use, the inner wall of the reactor has a thick layer of scaling material, and the scale layer is uneven, which is highly correlated with the structure inside the reactor. As can be seen from Figure 2, after the first leaching treatment, the scale layer on the outer layer of the reactor falls off and dissolves, and the scale layer is relatively uniform. The remaining undissolved scale is mainly a hard scale layer that has agglomerated due to heat. As can be seen from Figure 3, after the second leaching treatment, all the hard scale layers have fallen off, and a good dissolution effect has been achieved.

[0118] Example 2

[0119] A method for treating scaling material in an iron phosphate production device (same as in Example 1) in this embodiment includes the following steps:

[0120] S1: Rinse.

[0121] Use a high-pressure water gun to rinse the inner wall and stirring paddle of the ferric phosphate reactor. Use 500L of pure water at a water pressure of 20MPa for 5 minutes to remove materials with weak adhesion from the inner wall of the reactor and the surface of the stirring paddle.

[0122] S2: First leaching treatment.

[0123] After injecting 14695kg of pure water into the primary leachate tank, 2400kg of sulfuric acid was added to prepare 16m 3 , 1.5mol / L dilute sulfuric acid solution, the prepared dilute sulfuric acid solution is injected into 20m 3 In the reactor, the temperature was raised to 60°C and stirred for 100 minutes to leach out the scaling materials with slightly stronger adhesion.

[0124] The Fe and P concentrations in the leachate were tested every 20 minutes. At 80 and 100 minutes, the Fe and P concentrations increased from 4.11 g / L and 2.33 g / L at 80 minutes to 4.20 g / L and 2.35 g / L at 100 minutes, respectively. Leaching was stopped when the increase in Fe and P between tests was less than 0.3 g / L, and the primary leachate was recovered in the primary leachate storage tank.

[0125] S3: Second leaching treatment.

[0126] A mixed acid mixture of 1844kg of phosphoric acid (1 mol / L) and 3400kg of citric acid in a 1:1 molar ratio was added to the secondary leaching tank. The mixed acid was injected into the reactor after the first leaching treatment and allowed to soak at 60°C for 60 minutes. Then, stirring was started (at a linear speed of 6.00 m / s), and 2230kg of hydrogen peroxide and 92.9kg of Lan-826 were added. The temperature was raised to 95°C and leaching continued for 120 minutes to leach out the highly adhesive scaling materials. The molar concentration ratios of the phosphoric acid, citric acid, hydrogen peroxide, and Lan-826 were 1:1:0.4:0.05, respectively.

[0127] The Fe and P concentrations of the secondary leachate increased from 2.36 g / L and 27.76 g / L at 100 min to 2.55 g / L and 27.66 g / L at 120 min, respectively, after leaching for 100 min and 120 min. After leaching, the secondary leachate was recovered to the secondary leachate storage tank.

[0128] S4: Passivation.

[0129] After the second leaching, 173 kg of sodium carbonate and 32.65 kg of lauric acid were added to water to form a passivation solution with a mass concentration of 0.5% sodium carbonate and 0.2% lauric acid. The passivation solution was added to the reactor for passivation treatment at a temperature of 40°C for 90 minutes.

[0130] S5: Wash with water.

[0131] After the passivation was completed, the reactor was rinsed with pure water for 10 min until the conductivity of the washing liquid was 364 μm / cm.

[0132] Example 3

[0133] This embodiment provides a method for treating scaling materials in an iron phosphate production device (same as in Example 1), comprising the following steps:

[0134] S1: Rinse.

[0135] The inner wall and stirring paddle of the ferric phosphate reactor were rinsed with a high-pressure water gun. 1000L of pure water was used at a water pressure of 20MPa for 10 minutes to remove materials with weak adhesion from the inner wall of the reactor and the surface of the stirring paddle.

[0136] S2: First leaching treatment.

[0137] After injecting 14695kg of pure water into the primary leachate tank, 2400kg of sulfuric acid was added under stirring (linear speed 5.00m / s) to prepare 16m 3, 1.5mol / L dilute sulfuric acid solution, the prepared dilute sulfuric acid solution is injected into 20m 3 In the reactor, the temperature was raised to 80°C and stirred for 140 minutes to leach out the scaling materials with slightly stronger adhesion.

[0138] The Fe and P concentrations of the leachate were tested every 20 minutes. At 100, 120, and 140 minutes of leaching, the Fe and P concentrations increased from 3.98 g / L and 2.25 g / L at 100 minutes to 4.05 g / L and 2.28 g / L at 120 minutes, respectively. Finally, at 140 minutes of leaching, the concentrations were 4.20 g / L and 2.36 g / L, respectively (not shown in Table 1). Leaching was stopped when the increase in Fe and P content between the two tests was less than 0.3 g / L, and the primary leachate was recovered to the primary leachate storage tank.

[0139] S3: Second leaching treatment.

[0140] A mixed acid of 922kg of phosphoric acid (0.5mol / L) and 1783kg of malic acid in a molar ratio of 1:3 was added to the secondary leaching tank. The mixed acid was injected into the reactor after the first leaching treatment and allowed to soak at 90°C for 100 minutes. Then, stirring was started (at a linear speed of 5.00m / s). 1425kg of hydrogen peroxide and 16.80kg of dimethylthiourea were added and the temperature was raised to 95°C for a further 120 minutes to leach out the highly adhesive scaling materials. The molar concentration ratios of the phosphoric acid, malic acid, hydrogen peroxide, and dimethylthiourea were 1:3:0.5:0.02, respectively.

[0141] The Fe and P concentrations of the secondary leachate increased from 2.55 g / L and 15.38 g / L at 100 min to 2.77 g / L and 15.25 g / L at 120 min, respectively. After leaching, the secondary leachate was recovered to the secondary leachate storage tank.

[0142] S4 and S5 are the same as in Example 1.

[0143] Example 4

[0144] This embodiment provides a method for treating scaling materials in an iron phosphate production device (same as in Example 1), comprising the following steps:

[0145] S1: Rinse.

[0146] The inner wall and stirring paddle of the ferric phosphate reactor were rinsed with a high-pressure water gun. 500L of pure water was used at a water pressure of 15MPa for 5 minutes to remove materials with weak adhesion from the inner wall of the reactor and the surface of the stirring paddle.

[0147] S2: First leaching treatment.

[0148] After injecting 15130kg of pure water into the primary leachate tank, sulfuric acid was added to prepare 17m 3 , 2.5mol / L dilute sulfuric acid solution, the prepared dilute sulfuric acid solution is injected into 20m 3 In the reactor, the temperature was raised to 65°C and stirred for 120 minutes to leach out the scaling materials with slightly stronger adhesion.

[0149] The Fe and P concentrations of the leachate were tested every 20 minutes. When the increase in Fe and P content between two tests was less than 0.3 g / L, the leaching was stopped and the primary leachate was recovered to the primary leachate storage tank.

[0150] S3: Second leaching treatment.

[0151] A mixed acid prepared by combining phosphoric acid (same molar concentration as in Example 1) and sulfuric acid at a molar ratio of 1:4 was added to the secondary leaching tank. The mixed acid was injected into the reactor after the primary leaching treatment, allowed to soak at 75°C for 120 minutes, and then stirred (same as in Example 1). Hydrogen peroxide and hexamethylenetetramine were added, and the temperature was raised to 80°C and leached for 240 minutes to remove the highly adhesive scaling materials. When the secondary leaching time was extended to 240 minutes, the Fe and P concentrations in the leachate were 1.54 and 0.65 g / L, respectively (not shown in Table 2). This was not significantly increased compared to the sampling results at 140 minutes, demonstrating that the leaching effect was significant after the primary leaching and concentration, and the leachate concentration in the secondary leachate was reduced. The molar concentration ratios of phosphoric acid, sulfuric acid, hydrogen peroxide, and hexamethylenetetramine were 1:4:0.1:0.03, respectively. After leaching was completed, the secondary leachate was recovered to the secondary leachate storage tank.

[0152] S4: Passivation.

[0153] After the second leaching, 56 kg of trisodium phosphate and 16 kg of polyethylene glycol 400 were added to water to form a passivation solution with a mass concentration of 0.1% trisodium phosphate and 0.05% polyethylene glycol 400. The passivation solution was then added to the reactor for passivation treatment at 50°C for 60 minutes.

[0154] S5 is the same as in Example 1.

[0155] Example 5

[0156] This embodiment provides a method for treating scaling materials in an iron phosphate production device (same as in Example 1), comprising the following steps:

[0157] S1: Rinse.

[0158] The inner wall and stirring paddle of the ferric phosphate reactor were rinsed with a high-pressure water gun. 500L of pure water was used at a water pressure of 18MPa for 5 minutes to remove materials with weak adhesion from the inner wall of the reactor and the surface of the stirring paddle.

[0159] S2: First leaching treatment.

[0160] After injecting 15130kg of pure water into the primary leachate tank, sulfuric acid was added to prepare 18ml of 3 , 3mol / L dilute sulfuric acid solution, the prepared dilute sulfuric acid solution is injected into 20m 3 In the reactor, the temperature was raised to 75°C and stirred for 30 minutes to leach out the scaling materials with slightly stronger adhesion.

[0161] The Fe and P concentrations of the leachate were tested every 20 minutes. When the increase in Fe and P content between two tests was less than 0.3 g / L, the leaching was stopped and the primary leachate was recovered to the primary leachate storage tank.

[0162] S3: Second leaching treatment.

[0163] A mixed acid of phosphoric acid (same molar concentration as in Example 1) and sulfuric acid in a molar ratio of 1:2 was added to the secondary leaching tank. The mixed acid was injected into the reactor after the primary leaching treatment and allowed to soak at 85°C for 30 minutes. Stirring was then initiated (same as in Example 1), and hydrogen peroxide and urotropine were added. The temperature was raised to 90°C and leaching was continued for 60 minutes to remove the highly adhesive scaling materials. The molar concentration ratios of phosphoric acid, sulfuric acid, hydrogen peroxide, and urotropine were 1:2:0.2:0.10, respectively. After leaching was completed, the secondary leachate was recovered to the secondary leachate storage tank.

[0164] S4: Passivation.

[0165] After the second leaching, 56 kg of sodium hexametaphosphate (the mass concentration of sodium hexametaphosphate was 0.7%, and the amount of sodium hexametaphosphate used was 56 kg) and 16 kg of sodium dodecylbenzene sulfonate were added to water to mix into a passivation solution with a mass concentration of 0.7% sodium hexametaphosphate and 0.3% sodium dodecylbenzene sulfonate. The passivation solution was added to the reactor for passivation treatment. The passivation treatment temperature was 70°C and the time was 30 minutes.

[0166] S5 is the same as in Example 1.

[0167] Comparative Example 1

[0168] This comparative example provides a method for treating scaled materials in ferric phosphate production equipment. This method differs from Example 1 in that the primary leaching, secondary leaching, passivation, and water washing solutions used in this comparative example are all recycled solutions from Example 1. Specifically, the acid used in the first leaching in this comparative example is the primary leaching solution from Example 1, the acid used in the second leaching in this comparative example is the secondary leaching solution from Example 1, and the passivation agent and water washing solution used in this comparative example are all recycled solutions from Example 1.

[0169] The first leaching time was extended to 120 min, and the second leaching time was extended to 140 min.

[0170] In this comparative example, the condition of the inner wall of the reactor after the second leaching treatment is shown in Figure 4. As can be seen from Figure 4, although the leaching efficiency of the recycled leachate is reduced, it still has a good leaching effect and a good recycling rate. At the same time, Tables 1 and 2 also show that the leachate contains more Fe and P, and the leaching effect is good.

[0171] Comparative Example 2

[0172] This comparative example provides a method for treating scaled material from ferric phosphate production equipment. This method differs from Example 1 in that, in S3, the second leaching treatment uses 1.0 mol / L phosphoric acid, without using a mixed acid. The first leaching time is extended to 120 minutes, and the second leaching time is extended to 140 minutes.

[0173] In this comparative example, the condition of the inner wall of the reactor after the second leaching treatment is shown in Figure 5. As can be seen from Figure 5, the inner wall of the reactor cannot be leached and the leaching effect is poor.

[0174] Comparative Example 3

[0175] This comparative example provides a method for treating scaled material from ferric phosphate production equipment. This method differs from Example 1 in that, in S3, the second leaching treatment uses 4.0 mol / L phosphoric acid, without using a mixed acid. The first leaching time is extended to 120 minutes, and the second leaching time is extended to 140 minutes.

[0176] In this comparative example, the condition of the inner wall of the reactor after the second leaching treatment is shown in Figure 6. As can be seen from Figure 6, the inner wall of the reactor has been leached and the leaching effect is good. However, the phosphoric acid concentration is too high. Although the scale layer can be cleaned, the treatment cost is not advantageous. At the same time, it can be seen from the leachate that a high-concentration phosphoric acid solution will have a better descaling effect.

[0177] Comparative Example 4

[0178] This comparative example provides a method for treating scaled material from ferric phosphate production equipment. This method differs from Example 1 in that, in S3, an equal amount of sulfuric acid is replaced with nitric acid in the mixed acid used in the second leaching treatment. In this comparative example, the Fe and P concentrations in the secondary leachate increased from 2.48 g / L and 14.67 g / L at 100 min and 120 min, respectively, to 2.77 g / L and 14.81 g / L at 120 min. Although nitric acid has the same treatment effect on scale, it produces a relatively strong pungent odor during the leaching process.

[0179] Comparative Example 5

[0180] The difference between this comparative example and Example 1 is that S1 is not performed and steps S2 to S5 are performed directly. The first leaching time is extended to 120 minutes, and the second leaching time is extended to 140 minutes.

[0181] Comparative Example 6

[0182] The difference between this comparative example and Example 1 is that steps S1 and S2 are omitted and steps S3 to S5 are directly performed. The second leaching time is extended to 140 minutes.

[0183] Comparative Example 7

[0184] The difference between this comparative example and Example 1 is that S2 is not performed, and steps S3 to S5 are performed directly after S1. The second leaching time is extended to 140 minutes.

[0185] Comparative Example 8

[0186] The difference between this comparative example and Example 1 is that the molar concentration of phosphoric acid in the mixed acid of S3 is 0.1 mol / L and the second leaching time is extended to 140 min.

[0187] Comparative Example 9

[0188] The difference between this comparative example and Example 1 is that the molar concentration of phosphoric acid in the mixed acid of S3 is 2 mol / L.

[0189] Comparative Example 10

[0190] The difference between this comparative example and Example 1 is that the molar concentration ratio of phosphoric acid to sulfuric acid in the mixed acid of S3 is 1:0.5. The second leaching time is extended to 140 minutes.

[0191] Comparative Example 11

[0192] The difference between this comparative example and Example 1 is that in the mixed acid of S3, the molar concentration ratio of phosphoric acid to sulfuric acid is 1:5.

[0193] Comparative Example 12

[0194] The difference between this comparative example and Example 1 is that in S2, the temperature of the first leaching treatment is 50° C. The first leaching time is extended to 120 min, and the second leaching time is extended to 140 min.

[0195] Comparative Example 13

[0196] This comparative example differs from Example 1 in that, in S2, the temperature of the first leaching treatment was 25°C, the immersion time was 360 min (not shown in Table 1), and the leachate concentrations were 1.63 g / L and 1.01 g / L. The leaching temperature was too low, significantly reducing the efficiency and causing the secondary leachate to reach saturation more easily. The second leaching time was extended to 140 min.

[0197] Comparative Example 14

[0198] The difference between this comparative example and Example 1 is that in S3, the temperature of the second leaching treatment is 50° C. and the second leaching time is extended to 140 min.

[0199] Test example

[0200] Table 1 shows the comparative test results of the first leaching treatment process of Examples 1-5, Comparative Examples 1-5, and Comparative Examples 8-14. Table 2 shows the comparative test results of the second leaching treatment process of Examples 1-5 and Comparative Examples 1-14. The above specific data are all obtained by ICP-AES testing.

[0201] Table 1 Comparative test results of sampling during the first leaching process

[0202] It can be seen from Examples 1-3 in Table 1 that the first leaching treatment can dissolve part of the slag, and the leaching effect deteriorates after leaching for more than 80 minutes. It can be seen from Comparative Example 1 in Table 1 that after the leachate of Example 1 is reused twice, the leaching efficiency of the first leachate is still maintained at a good level.

[0203] It can be seen from the examples and comparative examples in Table 1 that if the method or conditions are inappropriate, problems such as poor removal of scaling materials or low efficiency or increased costs may occur.

[0204] Table 2 Comparative test results of sampling during the second leaching process

[0205] It can be seen from Examples 1-3 in Table 2 that the second leaching treatment can dissolve part of the slag, and the leaching effect deteriorates after leaching for more than 80 minutes (the initial leaching time is measured by the stirring start time); it can be seen from Comparative Example 1 in Table 2 that after the leachate of Example 1 is reused twice, the leaching efficiency of the leachate remains good; it can be concluded from Comparative Example 2 in Table 2 that when the acid used in the second leaching treatment is only 1 mol / L phosphoric acid, the leaching efficiency is low; it can be concluded from Comparative Example 3 in Table 2 that when the acid used in the second leaching treatment is only 4 mol / L phosphoric acid, the leaching efficiency is high, but the acid consumption is large.

[0206] It can be seen from the examples and comparative examples in Table 2 that if the method or conditions are inappropriate, problems such as poor removal of scaling materials or low efficiency or increased costs may occur.

[0207] In summary, the solution provided by the present disclosure has at least the following advantages:

[0208] (1) The present invention adopts two leaching processes to remove the scaling materials inside the scaling device. The acid liquid used is basically low-value acid, which not only reduces the amount of phosphoric acid used, is low-cost, but also can effectively clean and achieve significant treatment effects.

[0209] (2) The leachate produced during the leaching process can be recycled multiple times. When Fe and P are not saturated, the leaching effect can still maintain 80-90% of the initial effect. In addition, the recovered leachate can be used to prepare the reaction metal liquid and used for the synthesis of iron phosphate.

[0210] (3) The concentration of phosphoric acid used in the present disclosure does not exceed 10%, which greatly reduces the processing cost.

[0211] (4) The method provided by the present disclosure can avoid serious corrosion to equipment and is low in risk.

[0212] (5) The method provided in the present disclosure can be used to clean scaling materials in different equipment. For example, by heating the circulating leachate, the filter cloth of the filter press or the pipeline can be circulated and cleaned to remove blockage. Industrial Applicability

[0213] The method for treating scaling materials provided in the present disclosure is beneficial to reducing energy consumption, improving product consistency and quality, and increasing the service life of scaling equipment. It can effectively reduce costs, increase corporate benefits, and improve quality, which is in line with the company's concept of reducing costs and increasing efficiency.

Claims

1. A method for treating scaling materials, characterized in that: The following steps are involved: The scaling device to be treated is subjected to a first leaching treatment using dilute sulfuric acid, and the scaling device subjected to the first leaching treatment is subjected to a second leaching treatment using a mixed acid; The mixed acid includes phosphoric acid and other acids, and the other acids do not contain any one of hydrochloric acid, nitric acid, oxalic acid and hydrofluoric acid.

2. The method for treating scaling materials according to claim 1, characterized in that: The first leaching process includes at least one of the following features: Feature 1: The temperature of the first leaching treatment is 60℃-80℃; Feature 2: The first leaching treatment time is 30min-120min; Feature 3: The concentration of dilute sulfuric acid used in the first leaching treatment is 1.0mol / L-3.0mol / L; Feature 4: The volume of dilute sulfuric acid used in the first leaching treatment is not less than 80% of the volume of the scaling device; Feature 5: The first leaching treatment is carried out under stirring conditions.

3. The method for treating scaling materials according to claim 2, characterized in that: The temperature of the first leaching treatment is 70° C.-80° C.; and / or the concentration of the dilute sulfuric acid used in the first leaching treatment is 1.0 mol / L-2.5 mol / L.

4. The method for treating scaling materials according to any one of claims 1 to 3, characterized in that: The second leaching process includes at least one of the following features: Feature 1: The temperature of the second leaching treatment is 60℃-95℃; Feature 2: The molar concentration ratio of the phosphoric acid to the other acid is (1:1)-(1:4); Feature 3: The concentration of phosphoric acid in the mixed acid used in the second leaching treatment is 0.3 mol / L-1.0 mol / L; Feature 4: The other acid used in the second leaching treatment includes at least one of malic acid, citric acid and sulfuric acid.

5. The method for treating scaling materials according to claim 4, characterized in that: The molar concentration ratio of the phosphoric acid to the other acids is (1:2)-(1:3).

6. The method for treating scaling materials according to claim 4, characterized in that: The mixed acid used in the second leaching treatment contains phosphoric acid and sulfuric acid.

7. The method for treating scaling materials according to any one of claims 1 to 6, characterized in that: During the second leaching process, oxidants and corrosion inhibitors are also used.

8. The method for treating scaling materials according to claim 7, characterized in that: The molar concentration ratio of the phosphoric acid to the oxidant is (1:0.1)-(1:0.5), and / or the molar concentration ratio of the phosphoric acid to the corrosion inhibitor is (1:0.02)-(1:0.10).

9. The method for treating scaling materials according to claim 8, characterized in that: The molar concentration ratio of the phosphoric acid to the oxidant is (1:0.2)-(1:0.3), and / or the molar concentration ratio of the phosphoric acid to the corrosion inhibitor is (1:0.03)-(1:0.05).

10. The method for treating scaling materials according to any one of claims 7 to 9, characterized in that: The oxidant includes hydrogen peroxide; and / or the corrosion inhibitor includes at least one of hexamethylenetetramine, Lan-826 and dimethylthiourea.

11. The method for treating scaling materials according to any one of claims 7 to 10, characterized in that: The second leaching treatment comprises: firstly soaking the scaling device after the first leaching treatment with the mixed acid, and then adding the oxidant and the corrosion inhibitor to continue soaking.

12. The method for treating scaling materials according to claim 11, characterized in that: The mixed acid soaks the scaling device for 30 min to 120 min; and / or, the soaking time after adding the oxidant and the corrosion inhibitor is 60 min to 240 min.

13. The method for treating scaling materials according to claim 11, characterized in that: The oxidant and the corrosion inhibitor are added into the mixed acid in a stirring state.

14. The method for treating scaling materials according to any one of claims 1 to 13, characterized in that: Before the first leaching treatment, the method also includes: flushing the scaling device to be treated.

15. The method for treating scaling materials according to claim 14, characterized in that: Flushing is carried out under a water pressure of 15MPa-20MPa.

16. The method for treating scaling materials according to any one of claims 1 to 15, characterized in that: The descaling device obtained after the second leaching treatment is passivated.

17. The method for treating scaling materials according to claim 16, characterized in that: The reagents used in the passivation treatment include a passivating agent.

18. The method for treating scaling materials according to claim 17, characterized in that: The passivating agent includes at least one of sodium hydroxide, sodium carbonate, trisodium phosphate, sodium hexametaphosphate and sodium tripolyphosphate.

19. The method for treating scaling materials according to claim 17 or 18, characterized in that: The concentration of the passivating agent is 0.1%-0.7%.

20. The method for treating scaling materials according to any one of claims 17 to 19, characterized in that: The reagents used in the passivation treatment also include surfactants.

21. The method for treating scaling materials according to claim 20, characterized in that: The surfactant includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyethylene glycol 400 and lauric acid.

22. The method for treating scaling materials according to claim 21, characterized in that: The concentration of the surfactant is 0.05%-0.3%.

23. The method for treating scaling materials according to any one of claims 16 to 22, characterized in that: The temperature of the passivation treatment is 40° C.-70° C.; and / or the time of the passivation treatment is 30 min-180 min.

24. The method for treating scaling materials according to any one of claims 16 to 23, characterized in that: The descaling device after the passivation treatment is washed with water.

25. The method for treating scaling materials according to claim 24, characterized in that: The washing time is 10 min-30 min, and / or the washing is performed until the conductivity of the washing liquid obtained by washing is less than 500 μm / cm.

26. The method for treating scaling materials according to any one of claims 1 to 25, characterized in that: The primary leachate obtained from the first leaching treatment and / or the secondary leachate obtained from the second leaching treatment are recycled.

27. The method for treating scaling materials according to claim 26, characterized in that: The primary leaching solution and / or the secondary leaching solution are used to prepare the reaction metal liquid used for synthesizing ferric phosphate.

28. The method for treating scaling materials according to any one of claims 1 to 27, characterized in that: Fouling plants include iron phosphate production plants, filter presses or pipelines.

29. The method for treating scaling materials according to claim 28, characterized in that: The ferric phosphate production device is a reactor for producing ferric phosphate.

30. The method for treating scaling materials according to claim 29, characterized in that: The material of the reactor includes enamel, polytetrafluoroethylene or stainless steel.

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