Ammonium phosphate drum granulation method

Abstract

The invention discloses an ammonium phosphate drum granulation method which comprises the following steps: step 1) pre-reaction of a tube reaction tank and a pre-neutralization tank: acid sludge of a phosphoric acid device, a washing solution of a pre-washing tower and process water firstly enter a pre-washer and then enter the tube reaction tank, sulfuric acid is added, stirring reaction is performed in the tube reaction tank, and the reaction product is output through a tube C; acid sludge of a phosphoric acid device, washing liquid of a pre-washing tower and tail washing water enter a pre-neutralization tank, and the temperature of reaction slurry of the pre-neutralization tank is controlled through a steam pipe on the outer wall of the pre-neutralization tank and output through a pipe A and a pipe B; 2) mixing tube reaction: mixing the liquid in the tube A and the tube C to react again; and (3) granulating, namely feeding the liquid after reaction in the mixing tube into a granulator, and adding liquid ammonia for granulating to obtain the product. And the tube A, the tube B and the tube C react to realize a 2 + 1 tube reaction process (the tube A reaction, the tube B reaction and the tube C reaction). In the DAP production period, the high-solid-content slag acid and the extraction-residue concentrated acid are used in the tube reaction, and the slag acid and the extraction-residue concentrated acid directly enter the tubular reactor by bypassing a washing system, so that the DAP production cost is reduced, the stock pressure of the slag acid is relieved, and frequent blockage of the washing system caused by the high-solid-content slag acid and the extraction-residue concentrated acid is also avoided.

Description

Technical Field

[0001] The invention relates to the technical field of granulation, and in particular to a phosphate ammonium rotary drum granulation method. Background Art

[0002] As a country with a large population, my country's stable food supply is related to the national economy and people's livelihood. Given the current situation of limited land and large population, it is particularly important to ensure the quality and quantity of fertilizers, which are the food of food. However, as phosphate resources are gradually depleted and the proportion of slag acid in the phosphoric acid production process is increasing, how to make full use of high-solid slag acid to produce fertilizers suitable for agricultural production, and reasonably reduce production costs while ensuring product quality.

[0003] High-solid slag acid usually refers to an acidic waste liquid with a high level of suspended solids produced during the production of wet phosphoric acid. This slag acid contains a high level of solid impurities, such as phosphogypsum and undissolved ore particles, which results in a high viscosity and high difficulty in handling. High-solid slag acid is prone to deposition and blockage in the washing system of the diammonium phosphate (DAP) unit, and the residual concentrated acid has poor fluidity. After the slag acid and the residual concentrated acid react with the ammonia-containing tail gas to form slurry in the washing system, their fluidity further deteriorates and the pipe wall frequently scales. In addition, the slurry residence time is too long, which affects the qualified rate of the product water-to-water ratio (P2O5 water / P2O5). Summary of the invention

[0004] In view of the above problems, the object of the present invention is to provide a phosphate ammonium drum granulation method.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for granulating ammonium phosphate by rotary drum granulation comprises the following steps:

[0007] Step 1) Pre-reaction in the tube reactor and pre-neutralization tank: the acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the process water first enter the pre-washer and then the tube reactor, and then sulfuric acid is added, and stirred and reacted in the tube reactor, and then output from the tube C after the reaction;

[0008] The acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the tail washing water enter the pre-neutralization tank. The temperature of the reaction slurry in the pre-neutralization tank is adjusted through the steam pipe on the outer wall of the pre-neutralization tank and output through pipes A and B.

[0009] Step 2) Mixing tube reaction: the liquids in tube A and tube C are mixed and reacted again;

[0010] Step 3) Granulation: The liquid after the reaction in the mixing tube enters the granulator, and then liquid ammonia is added to granulate to obtain the product.

[0011] Further: in the step 1), the temperature of the acid slag entering is 40-60°C.

[0012] Further: in the step 1), the pre-reaction heating of the pre-neutralization tank, the heating temperature and the flow temperature in the tube C are 117-145°C.

[0013] Further: in the step 3), the material dust in the granulation process and the wastewater generated in the production process are washed by the wet line washing system, and the washing liquid after washing is returned to the pre-washing acid preparation and reused.

[0014] Further: in the steps 1) and 2), the devices used for the pre-reaction of the tube reaction tank, the pre-neutralization tank, and the mixing tube reaction include: a pre-neutralization tank, a tube reaction tank, a tube C, an output tube, a tube A, a tube B, a power pump, a cylinder, and an output tube;

[0015] The lower side wall of the pre-neutralization tank is connected to a pipe C;

[0016] An output pipe is arranged on the side wall of the lower part of the pipe inversion groove, and the output end of the output pipe is connected with pipe A and pipe B. Power pumps are arranged on pipe A and pipe B, and a cylinder is arranged on pipe A;

[0017] The cylinder is set as a round tube with two ends open, the output end of the tube C extends into the cylinder, and the output tube is connected to the side wall of the cylinder;

[0018] The output end of the tube C is arranged in the cylinder and the tube C in the cylinder is arranged as a hose;

[0019] Tube C is connected to the gas rod, and the gas rod is connected to the driving air pump.

[0020] Furthermore: the pre-neutralization tank and the tube reaction tank are both provided with a rotating shaft, the rotating shaft is driven by a first motor, a stirring paddle is provided at the lower part of the rotating shaft, and flow openings are evenly opened on the stirring paddle.

[0021] Further: the top of the pre-neutralization tank and the tube reverse tank is provided with a fixed plate, and the rotating shaft is provided on the fixed plate; the side walls of the pre-neutralization tank, the tube reverse tank and the fixed plate are all provided with grooves;

[0022] The pre-neutralization groove, the groove of the fixed plate, the pipe counter groove, and the groove of the fixed plate are all provided with cover plates, the side walls of the cover plates are provided with convex plates, and the cover plates are provided with handles.

[0023] Further: a second control valve is provided on each of the pipes A, B and C;

[0024] A steam pipe is spirally arranged on the side wall of the pre-neutralization tank, and a first control valve is arranged on the air inlet end of the steam pipe.

[0025] Further: a vibration mesh plate is arranged in the cylinder, and the vibration mesh plate is connected to the second motor.

[0026] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0027] (1) Tubes A, B, and C react to achieve a 2+1 tube reaction process (A tube reaction + B tube reaction + C tube reaction). During the production of DAP, the tube reaction uses high-solid residue acid and raffinate concentrated acid, and the residue acid and raffinate concentrated acid bypass the washing system and directly enter the tubular reactor, which reduces the production cost of DAP, relieves the inventory pressure of residue acid, and avoids frequent blockage of the washing system caused by high-solid residue acid and raffinate concentrated acid.

[0028] (2) The comprehensive utilization of concentrated acid and residue acid is achieved, replacing the traditional use of sulfuric acid to adjust the surplus nutrients of ammonium phosphate products, while ensuring that product quality meets standards and reducing production costs. This method is organically integrated with the original granulation system, washing system and FCS, which strengthens the operational difficulty brought by the new process and realizes a more flexible adjustment method for the surplus nutrients of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the present invention.

[0030] Figure 2 It is a schematic structural diagram of a cylinder of the present invention.

[0031] Figure 3 It is a schematic structural diagram of the steam pipe of the present invention.

[0032] Figure 4 It is a top view of the pre-neutralization tank of the present invention.

[0033] In the figure: 1-pre-neutralization tank, 2-tube reverse tank, 3-rotating shaft, 4-first motor, 5-stirring paddle, 6-steam pipe, 7-first control valve, 8-tube C, 9-output pipe, 10-tube A, 11-tube B, 12-power pump, 13-cylinder, 14-support beam, 15-gas rod, 16-driving air pump, 18-vibrating mesh plate, 19-second motor, 20-fixed plate, 21-groove, 22-cover plate, 23-convex plate, 24-handle, 25-output pipe. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] Embodiment 1:

[0036] The product quality inspection results of the products produced by the existing diammonium phosphate (DAP) device are shown in Table 1.

[0037] Table 1 Diammonium phosphate product inspection results

[0038]

[0039] As can be seen from Table 1, the effective P2O5, N and water-soluble P2O5 contents in the products produced by the existing diammonium phosphate (DAP) device from the acid slag, the washing liquid from the pre-wash tower and the process water all decreased to varying degrees. Increasing the solid content has a significant effect on adjusting the surplus nutrients of the DAP product and reducing the consumption of sulfuric acid. However, the water content in the product increased significantly, and the water-soluble P2O5 decreased significantly. The water-to-solid ratio (P2O5 water / P2O5) of some batches of products just reached the national standard, posing certain quality risks.

[0040] The diammonium phosphate (DAP) device is now improved, and a method for granulating ammonium phosphate by rotary drum is provided, which is specifically as follows:

[0041] (1) Pre-reaction of the tube reactor and pre-neutralization tank: the acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the process water first enter the pre-washer and then enter the tube reactor, and then sulfuric acid is added, and stirred and reacted in the tube reactor. After the reaction, it is output from tube C; the acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the tail washing water enter the pre-neutralization tank, and the reaction slurry temperature of the pre-neutralization tank is adjusted through the steam pipe on the outer wall of the pre-neutralization tank, and output from tubes A and B;

[0042] (2) Mixing tube reaction: The pre-reacted liquids in tubes A and C are mixed and reacted again;

[0043] (3) Granulation: The liquid after the reaction in the mixing tube enters the granulator, and then liquid ammonia is added to granulate to obtain the product. The material dust in the granulation process and the wastewater generated in the production process are washed today through the wet line washing system. The washing liquid after washing is returned to the pre-washing acid and reused.

[0044] Among them, the improved device is a phosphate ammonium rotary drum granulation tube reaction device, including: a pre-neutralization tank 1, a tube reaction tank 2, a rotating shaft 3, a first motor 4, a stirring paddle 5, a steam pipe 6, a first control valve 7, a pipe C8, an output pipe 9, a pipe A10, a pipe B11, a power pump 12, a cylinder 13, a support beam 14, a gas rod 15, a driving air pump 16, a vibrating mesh plate 18, a second motor 19, a fixed plate 20, a groove 21, a cover plate 22, a convex plate 23, a handle 24, and an output pipe 25.

[0045] The pre-neutralization tank 1 and the tube reaction tank 2 are both provided with a rotating shaft 3, which is driven by a first motor 4. A stirring paddle 5 is provided at the lower part of the rotating shaft 3, and flow openings are evenly opened on the stirring paddle 5.

[0046] A steam pipe 6 is spirally arranged on the side wall of the pre-neutralization tank 1 , and a first control valve 7 is arranged on the air inlet end of the steam pipe 6 .

[0047] A tube C8 is connected to the lower side wall of the pre-neutralization tank 1, an output tube 9 is arranged on the lower side wall of the tube counter tank 2, the output end of the output tube 9 is connected to the tube A10 and the tube B11, the tubes A10 and B11 are provided with a power pump 12, the tube A10 is provided with a cylinder 13, the cylinder 13 is arranged as a circular tube with openings at both ends, the output end of the tube C8 extends into the cylinder 13, the tubes A10, the tubes B11 and the tube C8 are all provided with a second control valve 14, and the side wall of the cylinder 13 is connected with an output tube 25.

[0048] The output end of tube C8 is arranged in the cylinder 13 and is set as a hose. Tube C8 is connected to the gas rod 15, which is a small gas rod. The gas rod 15 is connected to the driving air pump 16; a vibration mesh plate 18 is arranged in the cylinder 13, and the vibration mesh plate 18 is connected to the second motor 19.

[0049] A fixed plate 20 is arranged on the top of the pre-neutralization groove 1 and the tube reverse groove 2, and the rotating shaft 3 is arranged on the fixed plate 20. Grooves 21 are arranged on the side walls of the pre-neutralization groove 1, the tube reverse groove 2 and the fixed plate 20. Cover plates 22 are placed on the grooves 21 of the pre-neutralization groove 1 and the fixed plate 20 and the grooves 21 of the tube reverse groove 2 and the fixed plate 20. A convex plate 23 is arranged on the side wall of the cover plate 22, and a handle 24 is arranged on the cover plate 22.

[0050] Working process: the acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower and the tail washing water enter the pre-neutralization tank 1. A steam pipe 6 is spirally arranged on the outer wall of the pre-neutralization tank 1. The pre-neutralization tank 1 is provided with a rotating shaft 3, a first motor 4 and a stirring paddle 5, which are convenient for heating and mixing the liquid in the pre-neutralization tank 1 and then outputting it through the pipe C8.

[0051] The acid residue of the phosphoric acid device, the washing liquid of the pre-washing tower and the process water first enter the pre-washer and then enter the tube trough 2. The tube trough 2 is provided with a rotating shaft 3, a first motor 4 and a stirring paddle 5, so as to mix the liquid in the tube trough 2 and then output it through an output pipe 9. The output end of the output pipe 9 is connected with the tube A10 and the tube B11. The tube A10 is provided with a cylinder 13, and the cylinder 13 is configured as a circular tube with openings at both ends. The output end of the tube C8 extends into the cylinder 13. The liquids of the tubes A10 and C8 are mixed and reacted in the cylinder 13. The tube C8 is connected with a gas rod 15, which is a small gas rod. The gas rod 15 is connected with a driving air pump 16, so as to adjust the position of the output end of the tube C8 according to needs. A vibration mesh plate 18 is provided in the cylinder 13, and the vibration mesh plate 18 is connected with the second motor 19. It is convenient for mixing and reaction, and then output through the output pipe 25.

[0052] The pre-neutralization tank 1, the pipe reverse tank 2, and the fixed plate 20 are all provided with a groove 21, and the cover plate 22 is placed in the groove 21 for easy opening as needed.

[0053] The A tube reaction, the B tube reaction, and the C tube reaction increase the flexibility of adjusting the surplus nutrients of the DAP product during the production of DAP, and also contribute to the consumption of slag acid.

[0054] The spiral anti-blocking nozzle used in the C-tube reaction can adjust the slurry spraying angle from 90° to 49° as needed, solving the problems of limited distribution space for high-solid and high-viscosity slurry, slurry easily sprayed on the plow blade to form accumulation, affecting secondary ammoniation, etc. The process parameters of the A-tube reaction, B-tube reaction, and C-tube reaction are as follows:

[0055] Tubular reaction of tube A and tube B: Square nozzle 250×25mm, single set production capacity 30~45t / h;

[0056] A-tube and B-tube reaction pump: flow rate Q = 50m 3 / h, head H=70m, power: 90kW.h;

[0057] C-tube reaction: Spiral nozzle Processing capacity 8~20t / h;

[0058] C-tube reaction pump: flow rate Q = 30m 3 / h, head H=70m, power: 37kW.h.

[0059] By increasing the temperature of the slag acid, the temperature of the reaction slurry in the tube reactor is increased, and the residence time of the slag acid in the washing system is shortened, the moisture content and water-soluble P2O5 content of the product are improved. The test results are shown in Table 2 below.

[0060] Table 2 Product quality and temperature table

[0061]

[0062] Adjust the reaction spraying volume of pipe A and pipe B to 30-40m 3 / h, C tube reaction is 8-15m 3 / h, the total spraying volume increased after improving the slurry dispersion effect. The quality of the product after the reaction is shown in Table 3.

[0063] Table 3 Product quality after reaction

[0064]

[0065] During production, sulfuric acid consumption per ton of DAP product decreased from 11kg to 4kg, production capacity increased by 72,000 tons, 9,103 tons of slag acid (pure slag) and 4,883.4 tons of concentrated acid P2O5 (pure) were consumed, and a profit of 28.4772 million yuan was realized. The application of this technology increases the flexibility of regulating the surplus nutrients of DAP products, reduces production costs while increasing production capacity, provides food security, creates conditions for further reducing phosphogypsum emissions, and achieves the unity of social benefits, environmental benefits, and economic benefits.

[0066] Although the present invention is described herein with reference to a number of illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise many other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, drawings, and claims, a variety of variations and modifications may be made to the components and / or layout of the subject combination layout. In addition to the variations and modifications made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A method for granulating ammonium phosphate by rotary drum, characterized in that: The following steps are involved: Step 1) Pre-reaction in the tube reactor and pre-neutralization tank: the acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the process water first enter the pre-washer and then the tube reactor, and then sulfuric acid is added, and stirred and reacted in the tube reactor, and then output from the tube C after the reaction; The acid residue of the phosphoric acid device, the washing liquid of the pre-wash tower, and the tail washing water enter the pre-neutralization tank. The temperature of the reaction slurry in the pre-neutralization tank is adjusted through the steam pipe on the outer wall of the pre-neutralization tank and output through pipes A and B. Step 2) Mixing tube reaction: the liquids in tube A and tube C are mixed and reacted again; Step 3) Granulation: The liquid after the reaction in the mixing tube enters the granulator, and then liquid ammonia is added to granulate to obtain the product.

2. A method for granulating ammonium phosphate by rotary drum granulation according to claim 1, characterized in that: In the step 1), the temperature of the acid slag entering is 40-60°C.

3. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: In the step 1), the pre-reaction in the pre-neutralization tank is heated at a temperature of 117-145°C.

4. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: In the step 3), the material dust in the granulation process and the wastewater generated in the production process are washed by the wet line washing system, and the washing liquid after washing is returned to the pre-washing acid preparation and reused.

5. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: In the step 1) and the step 2), the devices used for the pre-reaction of the tube reaction tank and the pre-neutralization tank and the mixing tube reaction include: a pre-neutralization tank (1), a tube reaction tank (2), a tube C (8), an output pipe (9), a tube A (10), a tube B (11), a power pump (12), a cylinder (13), and an output pipe (25); the lower side wall of the pre-neutralization tank (1) is connected to the tube C (8); An output pipe (9) is arranged on the lower side wall of the pipe inversion tank (2), the output end of the output pipe (9) is connected to the pipe A (10) and the pipe B (11), a power pump (12) is arranged on the pipe A (10) and the pipe B (11), and a cylinder (13) is arranged on the pipe A (10); The cylinder (13) is configured as a circular tube with openings at both ends, the output end of the tube C (8) extends into the cylinder (13), and an output tube (25) is connected to the side wall of the cylinder (13); The output end of the tube C (8) is arranged in the cylinder (13) and the tube C (8) in the cylinder (13) is arranged as a hose; The tube C (8) is connected to the gas rod (15), and the gas rod (15) is connected to the driving air pump (16).

6. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: The pre-neutralization tank (1) and the tube reaction tank (2) are both provided with a rotating shaft (3), the rotating shaft (3) is driven by a first motor (4), a stirring paddle (5) is provided at the lower part of the rotating shaft (3), and flow openings are evenly opened on the stirring paddle (5).

7. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: A fixing plate (20) is arranged on the top of the pre-neutralization tank (1) and the tube reversing tank (2), and the rotating shaft (3) is arranged on the fixing plate (20); grooves (21) are arranged on the side walls of the pre-neutralization tank (1), the tube reversing tank (2) and the fixing plate (20); The pre-neutralization groove (1), the groove (21) of the fixing plate (20), the pipe counter groove (2), and the groove (21) of the fixing plate (20) are all provided with a cover plate (22), a convex plate (23) is provided on the side wall of the cover plate (22), and a handle (24) is provided on the cover plate (22).

8. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: The pipe A (10), the pipe B (11) and the pipe C (8) are all provided with a second control valve (14); A steam pipe (6) is spirally arranged on the side wall of the pre-neutralization tank (1), and a first control valve (7) is arranged on the air inlet end of the steam pipe (6).

9. A method for rotary drum granulation of ammonium phosphate according to claim 1, characterized in that: A vibration mesh plate (18) is arranged inside the cylinder (13), and the vibration mesh plate (18) is connected to a second motor (19).

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