A process for removing phosphorus from spent catalyst

Abstract

The present invention relates to the technical field of solid waste separation and extraction, and proposes a process method for removing phosphorus from a waste catalyst, comprising the following steps: S1, mixing the waste catalyst and carbonate evenly to obtain a roasted material, and obtaining a wet abrasive after roasting and wet grinding the roasted material; S2, adding water to the wet abrasive to obtain a mixed solution, adding a dephosphorizing agent to the mixed solution, stirring to remove phosphorus, and filtering to obtain a filtrate and a residue; the dephosphorizing agent includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate. Through the above technical scheme, the problem of more process equipment and higher energy consumption in the process method of leaching first and then removing phosphorus in the related art is solved, the dephosphorization effect is improved, and the metal loss is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of solid waste separation and extraction, and in particular to a process for removing phosphorus from waste catalysts. Background Art

[0002] At present, the process of phosphorus removal from waste catalysts is as follows: after alkaline roasting, the waste catalyst is wet-milled and countercurrently leached to obtain filter residue and leachate, the leachate is transferred to a stainless steel container with a heating and stirring device, and then a dephosphorizing agent is added to precipitate the phosphate ions and then removed by filtration to achieve the purpose of purification and phosphorus removal. It is worth noting that the material temperature after roasting is 200~300℃, the material temperature during leaching is 50~60℃, and the temperature during phosphorus removal is above 95℃, and the phosphorus slag produced during the phosphorus removal process will carry precious metals in the leachate, causing losses. It can be seen from this that the process of leaching first and then dephosphorization has the following disadvantages: ① There are many processes and equipment, and the operation is cumbersome; ② The energy consumption caused by multiple stirring, pumping and filtering processes is high; ③ The temperature of the material after roasting is not fully utilized, wasting a lot of heat energy; ④ The filtration performance is poor, resulting in a large loss of precious metals.

[0003] Patent CN104628032A discloses a method for preparing high-purity ammonium metavanadate from waste catalysts, which uses ion exchange resin to adsorb and remove phosphorus from the leachate obtained by leaching and filtering the waste catalyst, and then uses resin to adsorb molybdenum to separate vanadium to prepare high-purity ammonium metavanadate. This method still first adds water to the roasted clinker to leach and filter the nickel-aluminum slag to obtain a clear leachate, and then enters the ion exchange system to remove phosphorus. It has many processes and equipment, cumbersome operations, and high operating costs. Patent CN112174204A discloses a method for producing vanadium pentoxide from waste VPO catalysts, and its phosphorus removal method is also to filter the leached slurry first, and then add aluminum salt to the leachate to precipitate and remove phosphorus. This method has many processes and equipment and high energy consumption. Summary of the invention

[0004] The present invention proposes a process for removing phosphorus from waste catalysts, adopts a design concept of simultaneous leaching and phosphorus removal, solves the problem of more process equipment and higher energy consumption in the process method of leaching first and then removing phosphorus in the related art, improves the phosphorus removal effect and reduces metal loss.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a process for removing phosphorus from a waste catalyst, comprising the following steps:

[0007] S1. Evenly mixing the spent catalyst and the carbonate to obtain a calcined material, and calcining and wet-grinding the calcined material to obtain a wet abrasive;

[0008] S2, adding water to the wet abrasive to obtain a mixed solution, adding a dephosphorizing agent to the mixed solution, stirring to remove phosphorus, and filtering to obtain a filtrate and a residue;

[0009] The phosphorus removal agent includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate.

[0010] As a further technical solution, the mass ratio of the magnesium sulfate heptahydrate to magnesium 3-hydroxybutyrate is 4-9:1.

[0011] In the present invention, when the mass ratio of magnesium sulfate heptahydrate to magnesium 3-hydroxybutyrate is 4-9:1, it is beneficial to further improve the phosphorus removal effect and further reduce the soluble metal ions carried by the residue.

[0012] As a further technical solution, in step S2, the dephosphorization agent also includes sodium diformamide.

[0013] In the present invention, in order to further reduce the total phosphorus content and metal loss in the filtrate after phosphorus removal, on the one hand, it is necessary to promote the positive progress of the phosphorus removal reaction, and on the other hand, it is necessary to reduce the coagulation of soluble metal ions. The inventors found that sodium diformamide can play a synergistic role with magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate. Its addition helps to further improve the phosphorus removal effect and further reduce the soluble metal ions entrained in the residue.

[0014] As a further technical solution, the ratio of the sum of the masses of the magnesium sulfate heptahydrate and the magnesium 3-hydroxybutyrate to the mass of the sodium diformamide is 11:4-13:2.

[0015] In the present invention, when the mass ratio of the sum of the mass of magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate to the mass of sodium diformamide is 11:4-13:2, it helps to further improve the phosphorus removal effect and further reduce the soluble metal ions entrained in the residue.

[0016] As a further technical solution, in step S1, the waste catalyst is a vanadium-containing waste catalyst.

[0017] As a further technical solution, in step S1, the vanadium content of the vanadium-containing spent catalyst is 5wt%-25wt%, preferably 5wt%-15wt%, and more preferably 10wt%.

[0018] As a further technical solution, in step S1, the carbonate includes one or both of sodium carbonate and potassium carbonate, preferably sodium carbonate.

[0019] As a further technical solution, in step S1, the pH value of the roasted material is 10-11.

[0020] In the present invention, by controlling the pH value of the roasted material to be 10-11, the amount of acid and alkali used during stirring and dephosphorization is reduced, thereby reducing the dephosphorization cost.

[0021] As a further technical solution, in step S1, during the calcination, the temperature is 900-950°C and the time is 3-4 hours.

[0022] As a further technical solution, in step S1, the particle size of the wet abrasive is 50-60 mesh.

[0023] As a further technical solution, in step S2, the solid-liquid mass ratio of the mixed liquid is 1:2~3.

[0024] As a further technical solution, in step S2, the amount of the phosphorus removal agent added is 80 to 100 times the total phosphorus amount in the mixed solution in g / L.

[0025] As a further technical solution, in step S2, during the stirring for dephosphorization, the temperature is 90-100°C, the time is 2-3 hours, and the pH value is 9-10.

[0026] The working principle and beneficial effects of the present invention are:

[0027] In the present invention, the design idea of ​​leaching and dephosphorization is carried out simultaneously, which reduces the number of processes and equipment in the dephosphorization process, makes full use of the residual heat of roasting, reduces the energy consumption of dephosphorization, saves the cost of dephosphorization, and improves the filtering performance by mixing the dephosphorization slag and the leaching slag, which is beneficial to the subsequent extraction of metals. Among them, the dephosphorization agent used includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate. Through the combined use of inorganic and organic substances, the dephosphorization effect is improved and the soluble metal ions carried by the residue are reduced. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the following examples and comparative examples, unless otherwise specified, the vanadium content of the spent catalyst is 10 wt %.

[0030] Example 1

[0031] A process for removing phosphorus from a waste catalyst comprises the following steps:

[0032] S1. 50 tons of waste catalyst and sodium carbonate were mixed evenly to obtain a calcined material with a pH value of 10.5. The calcined material was calcined at 900° C. for 4 hours and then wet-milled to obtain a wet-milled material with a particle size of 50 meshes;

[0033] S2, adding water to the wet abrasive to obtain a mixed solution with a solid-liquid mass ratio of 1:2.5, adding a dephosphorizing agent to the mixed solution, stirring and dephosphorizing at 90° C. for 3 h under the condition of a pH value of 9, and filtering by pressure to obtain a filtrate and a residue;

[0034] Among them, the total phosphorus content in the mixed liquid is 0.75g / L. Calculated by g / L, the amount of phosphorus removal agent added is 60g / L. The phosphorus removal agent includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate. The amount of magnesium sulfate heptahydrate added is 40g / L, and the amount of magnesium 3-hydroxybutyrate added is 20g / L.

[0035] Example 2

[0036] A process for removing phosphorus from a waste catalyst comprises the following steps:

[0037] S1. 50 tons of waste catalyst and sodium carbonate were mixed evenly to obtain a calcined material with a pH value of 10.5. The calcined material was calcined at 950° C. for 3 hours and then wet-milled to obtain a wet-milled material with a particle size of 60 meshes;

[0038] S2, adding water to the wet abrasive to obtain a mixed solution with a solid-liquid mass ratio of 1:2.5, adding a dephosphorizing agent to the mixed solution, stirring and dephosphorizing at 100° C. for 2 h under the condition of a pH value of 10, and filtering by pressure to obtain a filtrate and a residue;

[0039] Among them, the total phosphorus content in the mixed liquid is 0.75g / L. Calculated by g / L, the amount of phosphorus removal agent added is 75g / L. The phosphorus removal agent includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate. The amount of magnesium sulfate heptahydrate added is 50g / L, and the amount of magnesium 3-hydroxybutyrate added is 25g / L.

[0040] Example 3

[0041] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of magnesium sulfate heptahydrate added is 70 g / L, and the amount of magnesium 3-hydroxybutyrate added is 5 g / L.

[0042] Example 4

[0043] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of magnesium sulfate heptahydrate added is 60 g / L, and the amount of magnesium 3-hydroxybutyrate added is 15 g / L.

[0044] Example 5

[0045] The only difference between this embodiment and embodiment 2 is that, in this embodiment, the amount of magnesium sulfate heptahydrate added is 67.5 g / L, and the amount of magnesium 3-hydroxybutyrate added is 7.5 g / L.

[0046] Example 6

[0047] The only difference between this embodiment and embodiment 5 is that in this embodiment, the phosphorus removal agent includes magnesium sulfate heptahydrate, magnesium 3-hydroxybutyrate and sodium diformamide, wherein the addition amount of magnesium sulfate heptahydrate is 63 g / L, the addition amount of magnesium 3-hydroxybutyrate is 7 g / L, and the addition amount of sodium diformamide is 5 g / L.

[0048] Example 7

[0049] The only difference between this embodiment and embodiment 5 is that in this embodiment, the phosphorus removal agent includes magnesium sulfate heptahydrate, magnesium 3-hydroxybutyrate and sodium diformamide, wherein the addition amount of magnesium sulfate heptahydrate is 45g / L, the addition amount of magnesium 3-hydroxybutyrate is 5g / L, and the addition amount of sodium diformamide is 25g / L.

[0050] Example 8

[0051] The only difference between this embodiment and embodiment 5 is that in this embodiment, the phosphorus removal agent includes magnesium sulfate heptahydrate, magnesium 3-hydroxybutyrate and sodium diformamide, wherein the addition amount of magnesium sulfate heptahydrate is 58.5 g / L, the addition amount of magnesium 3-hydroxybutyrate is 6.5 g / L, and the addition amount of sodium diformamide is 10 g / L.

[0052] Example 9

[0053] The only difference between this embodiment and embodiment 5 is that in this embodiment, the phosphorus removal agent includes magnesium sulfate heptahydrate, magnesium 3-hydroxybutyrate and sodium diformamide, wherein the addition amount of magnesium sulfate heptahydrate is 49.5 g / L, the addition amount of magnesium 3-hydroxybutyrate is 5.5 g / L, and the addition amount of sodium diformamide is 20 g / L.

[0054] Comparative Example 1

[0055] The difference between this comparative example and Example 1 is that in this comparative example, the phosphorus removal agent is only magnesium sulfate heptahydrate.

[0056] Comparative Example 2

[0057] The difference between this comparative example and Example 1 is that in this comparative example, the phosphorus removal agent is only magnesium 3-hydroxybutyrate.

[0058] Comparative Example 3

[0059] The only difference between this comparative example and Example 1 is that in this comparative example, magnesium 3-hydroxybutyrate is replaced by an equal amount of magnesium acetate.

[0060] The filtrates and residues in Examples 1 to 9 and Comparative Examples 1 to 3 were tested to detect the total phosphorus content in the filtrates and the soluble vanadium content in the residues. The test results are shown in Table 1 below.

[0061] Table 1 Test results

[0062]

[0063] The comparison between Example 1 and Comparative Examples 1 to 3 shows that the use of magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate as dephosphorizers significantly improves the dephosphorization effect through inorganic and organic synergy, and reduces the soluble metal ions carried by the residue. The comparison between Examples 2 to 3 and Examples 4 to 5 shows that when the mass ratio of magnesium sulfate heptahydrate to magnesium 3-hydroxybutyrate is 4 to 9: 1, it is beneficial to further improve the dephosphorization effect and further reduce the soluble metal ions carried by the residue. The comparison between Example 5 and Examples 6 to 9 shows that the addition of sodium diformamide in the dephosphorizer is beneficial to further improve the dephosphorization effect and further reduce the soluble metal ions carried by the residue. The comparison between Examples 6 to 7 and Examples 8 to 9 shows that when the sum of the mass of magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate and the mass ratio of sodium diformamide is 11: 4 to 13: 2, it helps to further improve the dephosphorization effect and further reduce the soluble metal ions carried by the residue.

[0064] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A process for removing phosphorus from spent catalyst, characterized in that: The following steps are involved: S1. Evenly mixing the spent catalyst and the carbonate to obtain a calcined material, and calcining and wet-grinding the calcined material to obtain a wet abrasive; S2, adding water to the wet abrasive to obtain a mixed solution, adding a dephosphorizing agent to the mixed solution, stirring to remove phosphorus, and filtering to obtain a filtrate and a residue; The dephosphorizing agent includes magnesium sulfate heptahydrate and magnesium 3-hydroxybutyrate; The mass ratio of magnesium sulfate heptahydrate to magnesium 3-hydroxybutyrate is 4-9:1; In step S2, the dephosphorizing agent further comprises sodium diformamide; The ratio of the sum of the masses of the magnesium sulfate heptahydrate and the magnesium 3-hydroxybutyrate to the mass of the sodium diformamide is 11:4 to 13:

2.

2. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S1, the pH value of the roasted material is 10-11.

3. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S1, during the calcination, the temperature is 900-950° C. and the time is 3-4 hours.

4. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S1, the particle size of the wet abrasive is 50-60 mesh.

5. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S2, the solid-liquid mass ratio of the mixed solution is 1:2-3.

6. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S2, the amount of the phosphorus removal agent added is 80 to 100 times the total phosphorus amount in the mixed solution in g / L.

7. The process for removing phosphorus from spent catalyst according to claim 1, characterized in that: In step S2, during the stirring and dephosphorization, the temperature is 90-100°C, the time is 2-3 hours, and the pH value is 9-10.

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