A process for preparing ferrous phosphate by one-step method using ferrous nitrate

Abstract

This invention discloses a one-step process for preparing ferrous phosphate using ferrous nitrate. The method comprises the following steps: S1: Iron powder and additive A are added to nitric acid under an inert gas atmosphere to react and obtain a ferrous nitrate solution; S2: Phosphoric acid and additive B are added to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture; S3: The ferrous phosphate mixture is cooled to crystallize, then filtered, washed, and ferrous phosphate is obtained. In S1, the concentration of nitric acid is 20-30%, the mass ratio of nitric acid to iron powder is 0.3-0.5:1, the reaction temperature is 20-40℃, and the temperature is maintained for 2-3 hours; additive A in S1 is at least one of sodium polyacrylate, rhamnolipid, or sucrose ester, and the amount of additive A added is 0.03-0.05:1 compared to the amount of iron powder. This invention simplifies the preparation process of ferrous phosphate, saves costs, and yields ferrous phosphate with high purity.

Description

Technical Field

[0001] This invention relates to the field of ferrous phosphate production technology, and in particular to a one-step process for preparing ferrous phosphate using ferrous nitrate. Background Technology

[0002] Currently, the preparation of ferrous phosphate often involves complex processes to avoid the formation of ferric ions, which not only wastes time but also increases production costs. Therefore, there is an urgent need to develop a simple process for preparing ferrous phosphate. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes a one-step process for preparing ferrous phosphate using ferrous nitrate, which simplifies the preparation process of ferrous phosphate, saves costs, and produces ferrous phosphate with high purity.

[0004] This invention proposes a one-step process for preparing ferrous phosphate using ferrous nitrate, the steps of which are as follows:

[0005] S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0006] S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 and react to obtain a ferrous phosphate mixture.

[0007] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0008] Preferably, the concentration of nitric acid in S1 is 20-30%, the mass ratio of nitric acid to iron powder is 0.3-0.5:1, the reaction temperature is 20-40℃, and the temperature is maintained for 2-3 hours.

[0009] Preferably, additive A in S1 is at least one of sodium polyacrylate, rhamnolipid, or sucrose ester, and the mass ratio of additive A to iron powder is 0.03-0.05:1.

[0010] Preferably, the apparatus for reacting iron powder and nitric acid includes a housing with an open upper end for receiving space. An internal rotating cylinder is rotatably connected to the housing, and the outer wall of the internal rotating cylinder is clearance-fitted with the inner wall of the housing. The lower end of the internal rotating cylinder passes through the housing and is connected to a drive device on the outside of the housing. The drive device drives the internal rotating cylinder to rotate continuously in different directions. A discharge pipe is connected to one side of the housing. An end cap is detachably provided at the upper end of the housing, and a feed pipe is connected to the end cap. A conveying pump is provided on the discharge pipe. A circulation pipe is also connected between the discharge pipe and the feed pipe. Solenoid valves are provided on the discharge pipe, the circulation pipe, and the feed pipe.

[0011] Preferably, the reaction temperature of phosphoric acid and ferrous nitrate in S2 is 20-30°C.

[0012] Preferably, the mass ratio of ferrous nitrate to phosphoric acid in S2 is 1.1-1.2:1.

[0013] Preferably, the phosphoric acid is added at a rate of 0.5-0.7 liters per hour in S2, and the stirring speed is 5-10 revolutions per minute.

[0014] Preferably, additive B in S2 is sodium borohydride, and the amount of additive B is 2%-3% of the mass of ferrous nitrate.

[0015] Preferably, carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.1-1 MPa.

[0016] Preferably, the pH of the S2 phosphoric acid is adjusted to 3-5 by adding magnesium hydroxide before reacting with ferrous nitrate, and the precipitate is filtered off.

[0017] Beneficial technical effects of the present invention:

[0018] This invention utilizes a one-step method to prepare ferrous phosphate using ferrous nitrate, which simplifies the preparation process of ferrous phosphate, saves costs, and yields ferrous phosphate with high purity.

[0019] In this invention, additive A is added during the reaction of nitric acid and iron powder. At the same time, by controlling the concentration of nitric acid and the reaction temperature, the formation of ferric ions is avoided while ensuring the preparation of ferrous nitrate.

[0020] In this invention, additive B is added during the reaction of ferrous nitrate and phosphoric acid to ensure the preparation of ferrous phosphate while avoiding the formation of ferric ions, thereby improving the purity of ferrous phosphate.

[0021] In this invention, magnesium hydroxide is added to adjust the pH to 3-5 before the reaction of phosphoric acid and ferrous nitrate, thereby effectively removing impurity metal ions from the phosphoric acid and improving the purity of the subsequently prepared ferrous nitrate.

[0022] In this invention, carbon dioxide is introduced during the reaction of phosphoric acid and ferrous nitrate, and a certain pressure is maintained. This further prevents the formation of ferric iron during the reaction, thereby improving the purity of ferrous phosphate.

[0023] The apparatus for the reaction of iron powder and nitric acid of the present invention includes a built-in rotating drum. Iron powder is added to the built-in rotating drum, and then nitric acid and additive A are added through the feed pipe to carry out the reaction. During the reaction, the built-in rotating drum is continuously rotated in different directions by a drive device, thereby increasing the reaction rate of iron powder and nitric acid. In addition, the reaction solution is circulated through a circulation pipe to further ensure the sufficiency of the reaction. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the apparatus for the reaction of iron powder and nitric acid proposed in this invention.

[0025] In the diagram: 1-shell, 2-end cap, 3-feed pipe, 4-circulation pipe, 5-solenoid valve, 6-discharge pipe, 7-transfer pump, 8-drive device, 9-built-in rotating drum, 10-through hole. Detailed Implementation

[0026] Reference Figure 1 The apparatus for reacting iron powder and nitric acid proposed in this invention includes a housing 1 with an open upper end for receiving space. An internal rotating cylinder 9 is rotatably connected to the housing 1, and the outer wall of the internal rotating cylinder 9 is clearance-fitted with the inner wall of the housing 1. The lower end of the internal rotating cylinder 9 penetrates the housing 1 and is connected to a drive device 8 on the outside of the housing 1. The drive device 8 drives the internal rotating cylinder 9 to continuously rotate in different directions. A discharge pipe 6 is connected to one side of the housing 1. An end cap 2 is detachably installed at the upper end of the housing 1, and a feed pipe 3 is connected to the end cap 2. A conveying pump 7 is installed on the discharge pipe 6. A circulation pipe 4 is also connected between the discharge pipe 6 and the feed pipe 3. Solenoid valves 5 are installed on the discharge pipe 6, the circulation pipe 4, and the feed pipe 3. The drive device can be a reversible motor to achieve continuous reversible rotation of the internal rotating cylinder.

[0027] The apparatus for the reaction of iron powder and nitric acid of the present invention includes a built-in rotating drum. Iron powder is added to the built-in rotating drum, and then nitric acid and additive A are added through the feed pipe to carry out the reaction. During the reaction, the built-in rotating drum is continuously rotated in different directions by a drive device, thereby increasing the reaction rate of iron powder and nitric acid. In addition, the reaction solution is circulated through a circulation pipe to further ensure the sufficiency of the reaction. Example 1

[0028] This invention proposes a one-step process for preparing ferrous phosphate using ferrous nitrate, the steps of which are as follows:

[0029] S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0030] S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture.

[0031] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0032] The concentration of nitric acid in S1 is 25%, and the amount of nitric acid and iron powder added is 4 kg and 10 kg, respectively. The reaction temperature is 30℃ and is maintained at a constant temperature for 2.5 h.

[0033] Additive A in S1 is sodium polyacrylate, and the amount of additive A added is 0.4 kg.

[0034] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 25℃; the addition amounts of ferrous nitrate and phosphoric acid are 11.5 kg and 10 kg, respectively; additive B is sodium borohydride, and the addition amount of additive B is 0.23 kg.

[0035] Carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.5 MPa.

[0036] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 4 by adding magnesium hydroxide and the precipitate was filtered off.

[0037] The purity of the prepared ferrous phosphate was tested and found to be 99.7%. Example 2

[0038] This invention proposes a one-step process for preparing ferrous phosphate using ferrous nitrate, the steps of which are as follows:

[0039] S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0040] S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture.

[0041] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0042] The concentration of nitric acid in S1 is 20%, and the amount of nitric acid and iron powder added is 3 kg and 10 kg, respectively. The reaction temperature is 20℃ and is maintained at a constant temperature for 2 hours.

[0043] Additive A in S1 is rhamnolipin, and the amount of additive A added is 0.3 kg.

[0044] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 25℃; the addition amounts of ferrous nitrate and phosphoric acid are 11kg and 10kg, respectively; additive B is sodium borohydride, and the addition amount of additive B is 0.22kg.

[0045] In S2, carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid, and the pressure above the solution is maintained at 1 MPa.

[0046] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 3 by adding magnesium hydroxide and then filtering out the precipitate.

[0047] The purity of the prepared ferrous phosphate was found to be 99.3%. Example 3

[0048] This invention proposes a one-step process for preparing ferrous phosphate using ferrous nitrate, the steps of which are as follows:

[0049] S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0050] S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture.

[0051] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0052] The concentration of nitric acid in S1 is 25%, and the amount of nitric acid and iron powder added is 5 kg and 10 kg, respectively. The reaction temperature is 40℃ and is maintained at a constant temperature for 3 hours.

[0053] In S1, additive A is sucrose ester, and the amount of additive A added is 0.5 kg.

[0054] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 30℃; the addition amounts of ferrous nitrate and phosphoric acid are 12kg and 10kg, respectively; additive B is sodium borohydride, and the addition amount of additive B is 0.36kg.

[0055] Carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.1 MPa.

[0056] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 5 by adding magnesium hydroxide and the precipitate was filtered off.

[0057] The purity of the prepared ferrous phosphate was found to be 99.6%.

[0058] Comparative Example 1

[0059] S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0060] S2: Add phosphoric acid to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture;

[0061] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0062] The concentration of nitric acid in S1 is 25%, and the amount of nitric acid and iron powder added is 4 kg and 10 kg, respectively. The reaction temperature is 30℃ and is maintained at a constant temperature for 2.5 h.

[0063] Additive A in S1 is sodium polyacrylate, and the amount of additive A added is 0.4 kg.

[0064] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 25℃; the amount of ferrous nitrate and phosphoric acid added is 11.5 kg and 10 kg, respectively.

[0065] Carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.5 MPa.

[0066] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 4 by adding magnesium hydroxide and the precipitate was filtered off.

[0067] The purity of the prepared ferrous phosphate was found to be 91.5%.

[0068] Comparative Example 2

[0069] S1: Iron powder is added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0070] S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture.

[0071] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0072] The concentration of nitric acid in S1 is 25%, and the amount of nitric acid and iron powder added is 4 kg and 10 kg, respectively. The reaction temperature is 30℃ and is maintained at a constant temperature for 2.5 h.

[0073] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 25℃; the addition amounts of ferrous nitrate and phosphoric acid are 11.5 kg and 10 kg, respectively; additive B is sodium borohydride, and the addition amount of additive B is 0.23 kg.

[0074] Carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.5 MPa.

[0075] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 4 by adding magnesium hydroxide and the precipitate was filtered off.

[0076] The purity of the prepared ferrous phosphate was found to be 89.7%.

[0077] Comparative Example 3

[0078] S1: Iron powder is added to nitric acid under inert gas to react and obtain ferrous nitrate solution;

[0079] S2: Add phosphoric acid to the ferrous nitrate solution prepared in S1 to react and obtain a ferrous phosphate mixture;

[0080] S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate.

[0081] The concentration of nitric acid in S1 is 25%, and the amount of nitric acid and iron powder added is 4 kg and 10 kg, respectively. The reaction temperature is 30℃ and is maintained at a constant temperature for 2.5 h.

[0082] The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 25℃; the amount of ferrous nitrate and phosphoric acid added is 11.5 kg and 10 kg, respectively.

[0083] Carbon dioxide is also introduced during the reaction of ferrous nitrate and phosphoric acid in S2, and the pressure above the solution is maintained at 0.5 MPa.

[0084] Before reacting with ferrous nitrate, S2 phosphoric acid was adjusted to pH 4 by adding magnesium hydroxide and the precipitate was filtered off.

[0085] The purity of the prepared ferrous phosphate was found to be 79.8%.

[0086] As can be seen from the experimental results of Example 1 and Comparative Examples 1-3, additive A was added during the reaction of nitric acid and iron powder. At the same time, by controlling the concentration of nitric acid and the reaction temperature, the formation of ferric ions was avoided while ensuring the preparation of ferrous nitrate. Meanwhile, additive B was added during the reaction of ferrous nitrate and phosphoric acid, which ensured the preparation of ferrous phosphate while avoiding the formation of ferric ions, thereby improving the purity of ferrous phosphate.

[0087] The above are merely 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 within the protection scope of the present invention.

Claims

1. A process for preparing ferrous phosphate in one step using ferrous nitrate, characterized in that, The steps are as follows: S1: Iron powder and additive A are added to nitric acid under inert gas to react and obtain ferrous nitrate solution; S2: Add phosphoric acid and additive B to the ferrous nitrate solution prepared in S1 and react to obtain a ferrous phosphate mixture. S3: Cool the ferrous phosphate mixture to crystallize, then filter and wash to obtain ferrous phosphate; In S1, additive A is at least one of sodium polyacrylate, rhamnolipin, or sucrose ester; The apparatus for reacting iron powder and nitric acid includes a housing with an opening at the top, and an inner rotating cylinder rotatably connected to the housing. The outer wall of the inner rotating cylinder is clearance-fitted with the inner wall of the housing. The lower end of the inner rotating cylinder passes through the housing and is connected to a drive device on the outside of the housing. The drive device drives the inner rotating cylinder to rotate continuously in different directions. Additive B in S2 is sodium borohydride.

2. The process for preparing ferrous phosphate using a one-step method with ferrous nitrate according to claim 1, characterized in that, The concentration of nitric acid in S1 is 20-30%, the mass ratio of nitric acid to iron powder is 0.3-0.5:1, the reaction temperature is 20-40℃, and the temperature is maintained for 2-3 hours.

3. The process for preparing ferrous phosphate using a one-step method with ferrous nitrate according to claim 1, characterized in that, The mass ratio of additive A to iron powder is 0.03-0.05:

1.

4. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, The built-in rotating drum has several through holes on its side wall. A discharge pipe is connected to one side of the housing. An end cap is detachably installed on the upper end of the housing. A feed pipe is connected to the end cap. A conveying pump is installed on the discharge pipe. A circulation pipe is also connected between the discharge pipe and the feed pipe. Solenoid valves are installed on the discharge pipe, the circulation pipe, and the feed pipe.

5. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, The reaction temperature of phosphoric acid and ferrous nitrate in S2 is 20-30℃.

6. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, The mass ratio of ferrous nitrate to phosphoric acid in S2 is 1.1-1.2:

1.

7. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, The phosphoric acid in S2 is added at a rate of 0.5-0.7 liters per hour, and the stirring speed is 5-10 revolutions per minute.

8. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, The amount of additive B is 2%-3% of the mass of ferrous nitrate.

9. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, In the process of the reaction between ferrous nitrate and phosphoric acid in S2, carbon dioxide is also introduced, and the pressure above the solution is maintained at 0.11 MPa.

10. The process for preparing ferrous phosphate in one step using ferrous nitrate according to claim 1, characterized in that, Before reacting with ferrous nitrate, the pH of the S2 phosphoric acid was adjusted to 3-5 by adding magnesium hydroxide, and the precipitate was filtered off.

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