Ferrous solution purification device

Abstract

The utility model discloses a kind of purification devices of ferrous solution, belong to iron phosphate production technical field.The device includes filter, liquid nitrogen storage tank, vaporizer, at least one acidification tank and multiple reaction kettle, acidification tank, reaction kettle and filter are sequentially connected by pipeline, reaction kettle is located indoors;The top of reaction kettle is equipped with exhaust pipe, exhaust pipe exports gas upwards outdoor and its upper end is equipped with fire arrester;The gas outlet of liquid nitrogen storage tank is connected with the gas inlet of multiple reaction kettle by pipeline with vaporizer and valve, and it is connected with the air separation section of synthetic ammonia generation line by liquid nitrogen pipeline;The pressure of gas in reaction kettle is 0.11-0.13Mpa;After adding ferrous solution in reaction kettle and before adding iron powder, liquid nitrogen storage tank replaces air in the upper portion of reaction kettle.In the air of upper portion of reaction kettle is replaced by nitrogen before reaction, a small amount of hydrogen is discharged with nitrogen, and explosion is avoided.The device is compact in structure, and the layout is reasonable.

Description

Technical Field

[0001] This utility model belongs to the field of ferric phosphate production technology, and specifically relates to a purification device for ferrous solution. Background Technology

[0002] Iron phosphate is a salt produced from iron and phosphorus sources and is a precursor to lithium iron phosphate, a cathode material for new energy. Currently, due to the explosive growth in demand for lithium iron phosphate, the demand for raw material iron phosphate is also continuously increasing.

[0003] Currently, the main processes for preparing iron phosphate include the sodium method and the ammonium method, which use purified phosphoric acid and industrial-grade monoammonium phosphate / battery-grade diammonium phosphate as phosphorus sources, respectively.

[0004] For example, patent application number CN202210470796.1 discloses a method for preparing battery-grade iron phosphate using agricultural-grade wet-process phosphoric acid. The method includes: purifying agricultural-grade wet-process phosphoric acid as a phosphorus source to obtain a phosphate reaction solution, and then reacting the phosphate reaction solution with an iron sulfate solution to obtain iron phosphate. The preparation method of the iron source includes: using ferrous sulfate heptahydrate crystals, a byproduct of titanium dioxide, as the iron source raw material, dissolving it in water, adding a pH adjuster to adjust the pH to 3-5, separating the solid and liquid to obtain a ferrous sulfate solution; then diluting the ferrous sulfate solution with water to control the ferrous sulfate content in the solution to 180-230 g / kg; finally adding an oxidant to the ferrous sulfate solution of the adjusted concentration for oxidation to obtain an iron sulfate solution, which is used as an iron source.

[0005] The applicant discovered during actual production that during storage and dissolution, a small amount of ferrous salts may be oxidized to ferric salts, affecting the production of ferric phosphate. Furthermore, in the sulfuric acid process for producing titanium dioxide, every ton of titanium dioxide produced generates 3.5-4 tons of ferrous sulfate as a byproduct. If untreated, this ferrous sulfate can only be disposed of as solid waste. Using this byproduct as an iron source can significantly reduce iron source costs. However, this ferrous sulfate typically contains high levels of impurities such as Ti, Mg, and Mn, which, if used directly in ferric phosphate synthesis, will result in a high impurity content in the product. Therefore, it is necessary to effectively remove impurities such as Ti, Mg, and Mn from the system beforehand.

[0006] In existing technologies, ferrous solution can be reacted with iron powder to reduce ferric ions to ferrous ions, while simultaneously removing some metal elements (e.g., through a displacement reaction). However, in actual production processes, it has been found that ferrous solution is usually acidic, and a small amount of iron powder will react with the acid to produce hydrogen gas. Although the amount of hydrogen gas is very small, multiple reaction vessels are usually involved. If there are many reaction vessels located indoors, hydrogen gas can accumulate indoors, potentially causing a fire or explosion, posing a safety hazard. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a purification device for ferrous solution. Before the reaction, nitrogen is used to replace the air in the upper part of the reaction vessel, and a small amount of hydrogen is discharged with the nitrogen, thus preventing an explosion. The technical solution is as follows:

[0008] This utility model embodiment provides a purification device for ferrous solution. The device includes a filter, at least one acidification tank 1, and multiple reaction vessels 2. The acidification tank 1, reaction vessels 2, and filter are connected sequentially by pipelines. The reaction vessels 2 are located indoors. The device also includes a liquid nitrogen storage tank 4 and a vaporizer 5. The top of the reaction vessel 2 is equipped with an exhaust pipe 6, which discharges gas upwards to the outside and has a flame arrester 7 at its upper end. The outlet of the liquid nitrogen storage tank 4 is connected to the inlet of the multiple reaction vessels 2 through a pipeline with a vaporizer 5 and a valve. It is connected to the air separation section of the ammonia synthesis production line through a liquid nitrogen pipeline. The pressure of the gas in the reaction vessel 2 is 0.11-0.13 MPa. After the ferrous solution is added to the reaction vessel 2 and before the iron powder is added, the liquid nitrogen storage tank 4 replaces the air in the upper part of the reaction vessel 2.

[0009] Furthermore, the device also includes two equipment platforms 3, with the reactor 2 and the filter located on the lower and upper platforms of the two equipment platforms 3, respectively; the acidification tank 1 is located beside the two equipment platforms 3 but not in front of them, and the front side of the lower platform is open; the exhaust pipe 6 first moves forward and then upward along the front side of the upper platform to the top of the two equipment platforms 3; and the liquid nitrogen storage tank 4 is located near the two equipment platforms 3.

[0010] In this embodiment of the present invention, the two-layer equipment platform 3 is a cubic structure. The rear, left and right sides of the lower platform are closed. The front, rear, left and right sides of the upper platform are closed, and windows are provided on the front, rear, left and / or right sides.

[0011] In this embodiment of the present invention, the exhaust pipe 6 is an iron pipe with a diameter greater than 30cm. Its horizontal section is fixed to the top of the lower platform by a fixing member 11, and its vertical section is fixed to the front side of the upper platform by a fixing member 11. The vertical sections of the exhaust pipes 6 of the multiple reaction vessels 2 are arranged side by side on the front side of the upper platform.

[0012] In this embodiment of the present invention, the multiple reaction vessels 2 are arranged in two rows, one in front and one behind. Each row of reaction vessels 2 includes multiple reaction vessels 2 arranged side by side. An operating table 8 is provided in the lower platform. The operating table 8 is located above all the reaction vessels 2. Its rear, left and right sides are fixedly connected to the corresponding sides of the lower platform. A guardrail is provided in front of it and a step 9 is provided between it and the bottom of the lower platform. The distance between it and the top of the lower platform is greater than 2m.

[0013] In this embodiment of the present invention, the liquid nitrogen storage tank 4 is a vertical storage tank, which is located in front of the two-layer equipment platform 3; the vaporizer 5 is an ambient temperature vaporizer, which is located next to the liquid nitrogen storage tank 4; and the edges of the areas where the liquid nitrogen storage tank 4 and the vaporizer 5 are located are provided with isolation railings 10.

[0014] In this embodiment of the present invention, there are multiple acidification tanks 1; each acidification tank 1 is a ground tank, which is a rectangular tank and is equipped with a stirrer; the multiple acidification tanks 1 are arranged in a rectangular array, located on the left or right side of the equipment platform 3, and a rain shelter is provided directly above them.

[0015] In this embodiment of the present invention, the reaction vessel 1 is a cylindrical structure with a horizontal top. The top of the vessel is provided with an air inlet and an iron powder addition structure, and a heater and a stirrer are provided on it.

[0016] Specifically, in this embodiment of the present invention, the volume of the liquid nitrogen storage tank 4 is 1 / 20 to 1 / 8 of the total volume of all reaction vessels 1.

[0017] The beneficial effects of the technical solution provided by this utility model embodiment are:

[0018] 1. Before the reaction, the air in the upper part of the reactor is replaced with nitrogen, and a small amount of hydrogen is discharged with the nitrogen, thus avoiding an explosion.

[0019] 2. This device has a compact structure and a reasonable layout.

[0020] 3. It can maintain a slight positive pressure in the reactor, ensuring that hydrogen is discharged in a timely manner.

[0021] 4. This device utilizes existing liquid nitrogen to produce nitrogen gas, which is low-cost; our company is a subsidiary of Xiangyun Group, which can provide phosphate, while Yunhuaan provides ammonia (with liquid nitrogen as an intermediate product) to Xiangyun Group; in reality, Yunhuaan is located next to our company, which facilitates the transportation of liquid nitrogen. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the ferrous solution purification device in an embodiment of this utility model;

[0023] Figure 2 This is a schematic diagram of the combined structure of the reactor and the two-layer equipment platform;

[0024] Figure 3 This is a layout diagram of the reactor.

[0025] In the diagram: 1 Acidification tank, 2 Reactor, 3 Two-layer equipment platform, 4 Liquid nitrogen storage tank, 5 Vaporizer, 6 Exhaust pipe, 7 Flame arrester, 8 Operating platform, 9 Steps, 10 Isolation railing, 11 Fixtures. Detailed Implementation

[0026] To make the objectives, technical solutions and advantages of this utility model clearer, the utility model will be described in further detail below with reference to the accompanying drawings.

[0027] Example 1

[0028] See Figure 1-3 Example 1 provides a purification device for ferrous sulfate solution. The device includes a filter, a two-layer equipment platform 3, a liquid nitrogen storage tank 4, a vaporizer 5, at least one acidification tank 1, and multiple reaction vessels 2. The acidification tank 1, reaction vessels 2, and filter are connected sequentially via pipelines. The acidification tank 1 is used to dissolve ferrous sulfate heptahydrate, a byproduct of titanium dioxide production, in acid. The following reaction occurs in the reaction vessels 2:

[0029] Fe 3+ +Fe→Fe 2+ ;

[0030] Fe + 2H + →Fe 2+ +H2.

[0031] There are many displacement reactions involved, which will be omitted in detail in this embodiment.

[0032] The reactor 2 and the filter are located on the lower and upper platforms of the two-layer equipment platform 3, respectively. The lower platform is open at the front, while the upper platform is closed. The acidification tank 1 is a ground tank containing a stirrer, located beside the two-layer equipment platform 3 but not in front of it. The reactor 1 is a cylindrical structure with a horizontal top. Its top has an air inlet (for nitrogen) and an iron powder addition structure, and it is equipped with a heater and a stirrer. An exhaust pipe 6 is located at the top. The filter can be a plate and frame filter press. The lower end of the exhaust pipe 6 connects to the exhaust port, directing the gas upwards to the outside, and its upper end is equipped with a flame arrester 7. Specifically, the exhaust pipe 6 first forms a horizontal section forward, then ascends along the front side of the upper platform (forming a vertical section) to the top of the two-layer equipment platform 3. The liquid nitrogen storage tank 4 is located near the two-layer equipment platform 3. Its outlet is connected to the inlets of multiple reaction vessels 2 via a pipeline equipped with a vaporizer 5 and valves. It is also connected to the air separation section of the ammonia synthesis production line via a liquid nitrogen pipeline. Specifically, it is a vertical storage tank. The gas pressure inside the reaction vessels 2 is 0.11-0.13 MPa, a slightly positive pressure, which can be maintained by introducing nitrogen and generating hydrogen. The vaporizer 5 is an ambient temperature vaporizer located next to the liquid nitrogen storage tank 4. An isolation fence 10 (specifically composed of multiple uprights) is installed at the edge of the area where the liquid nitrogen storage tank 4 and the vaporizer 5 are located.

[0033] After adding ferrous solution to reactor 2 (usually filling about 3 / 4 of its volume) and before adding iron powder, liquid nitrogen tank 4 replaces the air in the upper part of reactor 2, ideally keeping the oxygen content below 0.8%. During the reaction, nitrogen can also be added in appropriate amounts to maintain a slight positive pressure inside reactor 2, ensuring that hydrogen is discharged in a timely manner.

[0034] In this embodiment of the invention, the two-story equipment platform 3 is a cubic structure, specifically a two-story slab-type building structure (preferably with a single-story height greater than 5m). The rear, left, and right sides of the lower platform are enclosed. The front, rear, left, and right sides of the upper platform are enclosed, and windows are provided on its front, rear, left, and / or right sides.

[0035] In this embodiment of the invention, the exhaust pipe 6 is an iron pipe with a diameter greater than 30cm. Its horizontal section is fixed to the top of the lower platform by a fixing member 11 (specifically a pipe clamp), and its vertical section is fixed to the front side of the upper platform by a fixing member 11. The vertical sections of the exhaust pipes 6 of multiple reaction vessels 2 are arranged side by side on the front side of the upper platform.

[0036] Example 2

[0037] See Figure 3 Example 2 provides a purification device for ferrous solution, the structure of which is basically the same as that of Example 1, except that: in this example, the multiple reaction vessels 2 are arranged in two rows, one in front of the other, and each row of reaction vessels 2 includes multiple reaction vessels 2 arranged side by side. The two rows of reaction vessels 2 are staggered or not staggered.

[0038] Example 3

[0039] See Figure 2-3 Example 3 provides a purification device for ferrous solution, the structure of which is basically the same as that of Example 2, except that: in this example, the lower platform is equipped with an operating platform 8 (for the operator to stand on, so that the operator can add iron powder). The operating platform 8 is located above all the reaction vessels 2, it is horizontally arranged, it is arranged around the reaction vessels 2, and its rear, left and right sides are fixedly connected to the corresponding sides of the lower platform. There is a guardrail in front of it and a step 9 (sloping, so that the operator can climb onto the operating platform 8) between it and the bottom of the lower platform. The distance between it and the top of the lower platform is greater than 2m to ensure that the operator can stand on the operating platform 8.

[0040] Example 4

[0041] See Figure 1 Example 4 provides a purification device for ferrous solution, which has a structure that is basically the same as that of Example 1, except that the liquid nitrogen storage tank 4 in this example is located in front of the two-layer equipment platform 3.

[0042] Example 5

[0043] See Figure 1 Example 5 provides a purification device for ferrous solution, the structure of which is basically the same as that of Example 1, except that the acidification tank 1 in this example is a rectangular tank and there are multiple of them. The multiple acidification tanks 1 are arranged in a rectangular array, located on the left or right side of the equipment platform 3, and a rain shelter (not shown) is provided directly above them.

[0044] Example 6

[0045] Example 6 provides a purification device for ferrous solution, which has a structure that is basically the same as that of Example 1. The difference is that in this example, the acidification tank 1 is located on the left side of the equipment platform 3, and the liquid nitrogen storage tank 4 and the vaporizer 5 are arranged side by side on the left and right sides and are located 3-5 meters in front of the equipment platform 3 to facilitate back-and-forth operation.

[0046] Example 7

[0047] Example 7 provides a purification device for ferrous solution, which has a structure that is basically the same as that of Example 1. The difference is that the volume of the liquid nitrogen storage tank 4 in this example is 1 / 20 to 1 / 8 of the total volume of all reaction vessels 1 to ensure a sufficient supply of nitrogen.

[0048] Example 8

[0049] Example 8 provides a purification device for ferrous solution, the structure of which is basically the same as that of Example 1, except that the number of reaction vessels 2 in this example is 6. The volume of reaction vessel 2 is 40m³. 3 , 30m of ferrous solution before the reaction 3 Feeding reaction, nitrogen purging of the upper space 10m 3 Liquid nitrogen storage tank 4 has a volume of 20m³. 3 Vaporizer 5 is installed as a matching component. Both liquid nitrogen storage tank 4 and vaporizer 5 were purchased from Zhongjie Special Equipment. The requirement is that the oxygen content after replacement should be below 0.8%. The calculation formula is: VT=VR ln(21 / 0.008), where VT is the nitrogen consumption and VR is the tank volume. VT=10*3.267=32.67M 3 Generally, two replacements are sufficient. After measuring the gas content, a second replacement is performed if the result is unsatisfactory. The calculation is based on three replacements. The nitrogen inlet flow rate is as follows: 32.67 * 3 / 0.5 = 196.2 standard cubic meters per hour. The nitrogen inlet flow rate for a single reactor is designed to be 200 cubic meters per hour, with a total of 6 reactors. The standard boiling point of nitrogen is -195.8℃, and its liquid density is 0.808 (at -195.8℃). 1 m³ 3 Liquid nitrogen can be vaporized into nitrogen gas at a rate of 808 / 28*22.4=646.4 cubic meters; stored nitrogen gas can be used for 20*646.4 / 200=64.64 hours.

[0050] In this embodiment, valves, flow meters, etc., are installed on the pipelines between the various structures as needed.

[0051] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A purification device for ferrous solution, comprising a filter, at least one acidification tank (1), and multiple reaction vessels (2), wherein the acidification tank (1), reaction vessels (2), and filter are connected sequentially by pipelines, and the reaction vessels (2) are located indoors; characterized in that, The device also includes a liquid nitrogen storage tank (4) and a vaporizer (5). The top of the reactor (2) is provided with an exhaust pipe (6), which discharges the gas upward to the outside and is provided with a flame arrester (7) at its upper end. The outlet of the liquid nitrogen storage tank (4) is connected to the inlet of multiple reactors (2) through a pipeline with a vaporizer (5) and a valve. It is connected to the air section of the ammonia synthesis line through a liquid nitrogen pipeline. The pressure of the gas in the reactor (2) is 0.11-0.13 MPa. After the ferrous solution is added to the reactor (2) and before the iron powder is added, the liquid nitrogen storage tank (4) replaces the air in the upper part of the reactor (2).

2. The purification device for ferrous solution according to claim 1, characterized in that, It also includes two equipment platforms (3), with the reactor (2) and filter located on the lower and upper platforms of the two equipment platforms (3), respectively; the acidification tank (1) is located next to the two equipment platforms (3) and not in front of the two equipment platforms (3), with the front side of the lower platform open; the exhaust pipe (6) first moves forward and then moves upward along the front side of the upper platform to the top of the two equipment platforms (3); the liquid nitrogen storage tank (4) is located near the two equipment platforms (3).

3. The purification device for ferrous solution according to claim 2, characterized in that, The two-layer equipment platform (3) is a cubic structure. The rear, left and right sides of the lower platform are closed. The front, rear, left and right sides of the upper platform are closed, and windows are provided on the front, rear, left and / or right sides.

4. The purification device for ferrous solution according to claim 2, characterized in that, The exhaust pipe (6) is an iron pipe with a diameter greater than 30cm. Its horizontal section is fixed to the top of the lower platform by a fixing member (11), and its vertical section is fixed to the front side of the upper platform by a fixing member (11). The vertical sections of the exhaust pipes (6) of multiple reactors (2) are arranged side by side on the front side of the upper platform.

5. The purification device for ferrous solution according to claim 2, characterized in that, Multiple reactors (2) are arranged in two rows, one in front of the other. Each row of reactors (2) includes multiple reactors (2) arranged side by side. An operating table (8) is provided in the lower platform. The operating table (8) is located above all the reactors (2). Its rear, left and right sides are fixedly connected to the corresponding sides of the lower platform. A guardrail is provided in front of it and a step (9) is provided between it and the bottom of the lower platform. The distance between it and the top of the lower platform is greater than 2m.

6. The purification device for ferrous solution according to claim 2, characterized in that, The liquid nitrogen storage tank (4) is a vertical tank located in front of the two-layer equipment platform (3); the vaporizer (5) is an ambient temperature vaporizer located next to the liquid nitrogen storage tank (4); the edges of the areas where the liquid nitrogen storage tank (4) and the vaporizer (5) are located are equipped with isolation barriers (10).

7. The purification device for ferrous solution according to claim 2, characterized in that, There are multiple acidification tanks (1); each acidification tank (1) is a ground tank, which is a rectangular tank and has a stirrer inside; multiple acidification tanks (1) are arranged in a rectangular array, located on the left or right side of the equipment platform (3), and a rain shelter is provided directly above them.

8. The purification device for ferrous solution according to claim 1, characterized in that, The reactor (2) is a cylindrical structure with a horizontal top. It has an air inlet and an iron powder addition structure on the top, and a heater and a stirrer are provided on it.

9. The purification device for ferrous solution according to claim 1, characterized in that, The volume of the liquid nitrogen storage tank (4) is 1 / 20 to 1 / 8 of the total volume of all the reaction vessels (2).

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