Production method of phosphoric acid with low antimony ion content

Abstract

The invention discloses a production method of phosphoric acid with low content of antimony ions, which comprises the following steps: conveying liquid yellow phosphorus to a phosphorus combustion furnace to carry out combustion reaction with oxygen in air to generate phosphorus pentoxide gas, conveying the phosphorus pentoxide gas to a hydration absorption tower by negative pressure, absorbing the phosphorus pentoxide gas by low-concentration phosphoric acid circulated by a concentrated acid pump to generate crude phosphoric acid, when the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirement, arsenic removal operation of a purification procedure is performed, crude phosphoric acid and a gas purifying agent are fully mixed and then enter an arsenic removal reactor, a precipitator and an arsenic removal filter, finally, the mixture enters a degassing tower to remove excessive gas purifying agent, and after degassing, the mixture enters an adjusting tower to adjust the concentration to obtain a finished product. A common solid purifying agent in the prior art is changed into a gas purifying agent, impurities such as arsenic and antimony in the gas purifying agent are removed through mixed reaction of the gas purifying agent and crude phosphoric acid in a pipeline mixer, excessive gas purifying agent is removed through degassing, and finally the content of antimony phosphate ions is smaller than 700 ppb.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphoric acid production, and in particular relates to a method for producing phosphoric acid with a low antimony ion content. Background Art

[0002] Yellow phosphorus is an extremely important basic industrial raw material, mainly used in the following fields: Yellow phosphorus is an important raw material for the manufacture of organophosphorus pesticides, such as trichlorfon, methyl ammonium phosphate, chlorpyrifos, dichlorvos, etc. Yellow phosphorus is also used to produce phosphorus compounds such as thermal phosphoric acid, phosphorus trichloride, phosphorus oxychloride, phosphorus pentasulfide, and is used in oil extraction, printing and dyeing, papermaking, leather making, alloys, washing and other industries. Yellow phosphorus is also used as a food additive and feed additive. Yellow phosphorus can also be used to manufacture flame retardant materials and raw materials for lithium batteries.

[0003] Yellow phosphorus usually contains impurities, which mainly come from raw materials and production processes. Common impurities include metal impurities (such as arsenic, silicon, iron, sulfur, etc.), organic impurities (such as oil), and mechanical impurities that have not been rinsed and filtered clean. Among them, arsenic is one of the most difficult impurities to remove, and it is also one of the impurities with a higher content in yellow phosphorus. There are two methods for purifying yellow phosphorus: chemical and physical methods. The chemical purification method involves adding specific chemical reagents to react chemically with impurities in yellow phosphorus to generate soluble compounds or precipitates, which are then removed through filtering, washing, and other steps. The physical separation method uses the differences in physical properties between yellow phosphorus and impurities (such as density, melting point, boiling point, etc.) to separate impurities through distillation, crystallization, filtration, and other methods.

[0004] Chinese invention patent CN116216670A provides a method for simultaneously removing arsenic and antimony from yellow phosphorus, wherein the yellow phosphorus liquefied by heating is fully stirred and mixed with a water-phase basic oxidant in a reactor under the condition of hot water liquid sealing, and a dispersant, an acidulant and a catalyst are added, and stirred at 55-65°C, so that the arsenic and antimony impurities in the yellow phosphorus enter the water phase after reaction, and then washed and allowed to stand for phase separation to obtain a high-purity yellow phosphorus with low arsenic and low antimony. Hydrogen peroxide is used as a basic oxidant, and a small amount of phosphoric acid or polyphosphoric acid is added as an acidulant, and no new impurity ions are introduced. The effect of removing arsenic and antimony impurities from yellow phosphorus by the above scheme is unknown, and the antimony ion content of the existing thermal phosphoric acid production method is relatively high, usually reaching more than 3500ppb, mainly because the raw material yellow phosphorus contains a large amount of antimony ions (greater than 22000ppb), and it is difficult to remove such a large amount of antimony ions by the post-processing method.

[0005] Therefore, the present invention provides a method for producing phosphoric acid with a low antimony ion content, which is used to solve the technical problems existing in the above-mentioned background technology. Summary of the invention

[0006] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a method for producing phosphoric acid with a low antimony ion content, to optimize the process of removing yellow phosphorus, to reduce the antimony ion content in yellow phosphorus, and to reduce the unit consumption of purifiers to a certain extent.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0008] The invention discloses a method for producing phosphoric acid with low antimony ion content. Liquid yellow phosphorus is transported to a phosphorus burning furnace for combustion reaction with oxygen in the air to generate phosphorus pentoxide gas. The phosphorus pentoxide gas is transported to a hydration absorption tower by negative pressure and absorbed by low-concentration phosphoric acid circulated by a concentrated acid pump to generate crude phosphoric acid. When the specific gravity of the phosphoric acid in the hydration absorption tower meets the process requirements, an arsenic removal operation is performed in a purification process. The crude phosphoric acid is fully mixed with a gas purifier and then enters an arsenic removal reactor, a precipitator and an arsenic removal filter. Finally, the crude phosphoric acid enters a degassing tower to remove excess gas purifier. After degassing, the crude phosphoric acid enters an adjustment tower to adjust the concentration to obtain a finished product.

[0009] Further defined, the method comprises the following specific steps:

[0010] Step 1: transporting the unwashed yellow phosphorus to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, using a phosphorus spray gun to assist combustion, and controlling the air pressure of the phosphorus spray gun to be stable between 400 kPa and 500 kPa;

[0011] Step 2: The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank;

[0012] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 65 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0013] Step 3: When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with a gas purifier at a pressure of 50 to 90 kPa in a pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0014] It is further defined that in step 1, a compressed air bag is used and the air is drained once every hour to ensure that there is no condensed water and other iron filings impurities in the air.

[0015] It is further defined that the phosphorus content of the yellow phosphorus is 99.9% or above, and the appearance is light yellow or transparent waxy solid.

[0016] It is further defined that the semi-finished yellow phosphorus product is washed in the transfer tank in step 2, the temperature of the yellow phosphorus and the washing water is controlled between 60 and 75° C., and the washing time is not less than 2 hours.

[0017] It is further defined that in step one, byproduct steam is generated, and the byproduct steam enters the steam drum above the phosphorus burning furnace, and the steam then passes through the cylinder for use in the production of heat preservation and power generation devices.

[0018] It is further defined that process water is added to the hydration absorption tower in step 2 to carry out hydration reaction, and the process water uses demineralized water that has been treated with anion and cation exchange.

[0019] It is further defined that the conductivity of the desalted water is less than 30 us / cm, the sodium ion is less than 100 ppb, and the iron ion is less than 30 ppb.

[0020] It is further defined that the low-concentration phosphoric acid circulated by the concentrated acid pump in step three is also the circulating acid. When the iron ion content of the circulating acid is less than 150 ppb, the circulating acid and the gas purifier are fully mixed in the pipeline mixer and then enter the arsenic removal reactor.

[0021] Beneficial effects of the present invention:

[0022] The invention provides a method for producing phosphoric acid with a low content of antimony ions. The method innovates yellow phosphorus impurity removal treatment and post-treatment process control. First, the yellow phosphorus is transported from a storage tank to a transfer tank, water is circulated in the transfer tank to clean the yellow phosphorus to remove most of the antimony ions, and then the impurity-removed yellow phosphorus is transported to a production storage tank, and then transported to a phosphorus burning furnace by a submersible pump to burn to generate crude phosphoric acid, and then transported to a hydration absorption tower. After hydration, the antimony ion content of the crude phosphoric acid is less than 3000 ppb, and in the purification treatment, the solid purifier commonly used in the prior art is replaced by a gas purifier, and impurities such as arsenic and antimony are removed from the crude phosphoric acid through a pipeline mixer, and then excess gas purifier is removed through degassing, so that the antimony ion content of the phosphate finally obtained is less than 700 ppb.

[0023] The method of the present invention firstly reduces the content of antimony ions in the raw material yellow phosphorus from more than 22000 ppb to less than 10000 ppb, and finally reduces the content of antimony ions in the produced phosphate from more than 3500 ppb to less than 700 ppb, thereby greatly improving the product quality of thermal phosphoric acid and reducing the unit consumption of the purifier to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0025] Figure 1 A flowchart of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0026] Figure 2 A process flow chart of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0027] Figure 3 FIG2 is a process flow diagram of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0028] Figure 4 Figure 3 is a process flow diagram of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0029] Figure 5 Four process flow diagrams of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0030] Figure 6 Figure 5 is a process flow diagram of an embodiment of a method for producing phosphoric acid with a low content of antimony ions according to the present invention;

[0031] Figure 7 This is a test data diagram of an embodiment of a method for producing phosphoric acid with a low antimony ion content in the present invention. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings 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 the field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0034] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Example 1: Figure 1 As shown, a method for producing phosphoric acid with a low content of antimony ions of the present invention comprises the following steps: transporting liquid yellow phosphorus to a phosphorus burning furnace for combustion reaction with oxygen in the air to generate phosphorus pentoxide gas; the phosphorus pentoxide gas is transported to a hydration absorption tower by negative pressure to be absorbed by low-concentration phosphoric acid circulated by a concentrated acid pump to generate crude phosphoric acid; when the specific gravity of the phosphoric acid in the hydration absorption tower meets the process requirements, an arsenic removal operation is performed in a purification process; the crude phosphoric acid is fully mixed with a gas purifier and then enters an arsenic removal reactor, a precipitator and an arsenic removal filter; and finally enters a degassing tower to remove excess gas purifier; after degassing, the gas purifier enters an adjustment tower to adjust the concentration to obtain a finished product.

[0036] In the application of this embodiment, the specific steps of the method are as follows:

[0037] Step 1: transporting yellow phosphorus without water washing to a phosphorus burning furnace (transport efficiency of 5.5 tons / hour) to react with oxygen in the air to generate phosphorus pentoxide gas, using a phosphorus spray gun to assist combustion, and controlling the air pressure of the phosphorus spray gun to be stable between 400 kPa and 500 kPa;

[0038] Step 2: The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank;

[0039] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 75 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0040] Step 3: When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with a gas purifier at a pressure of 50 to 60 kPa in a pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0041] In the application of this embodiment, a compressed air bag is used in step 1 and the air is drained once every hour to ensure that there is no condensed water and other iron filings impurities in the air.

[0042] In the application of this embodiment, the phosphorus content of the yellow phosphorus is 99.9% or above, and the appearance is light yellow or transparent waxy solid.

[0043] In the application of this embodiment, the transfer tank in step 2 washes the semi-finished yellow phosphorus, the temperature of the yellow phosphorus and the washing water is controlled between 60 and 75° C., and the washing time is not less than 2 hours.

[0044] In the application of this embodiment, by-product steam is generated in step 1, and the by-product steam enters the steam drum above the phosphorus burning furnace, and the steam is then passed through the cylinder for use in the production of heat preservation and power generation devices.

[0045] In the application of this embodiment, process water is added to the hydration absorption tower in step 2 to carry out hydration reaction, and the process water uses demineralized water that has been treated with anion and cation exchange.

[0046] In the application of this embodiment, the conductivity of the desalted water is less than 30 us / cm, the sodium ion is less than 100 ppb, and the iron ion is less than 30 ppb.

[0047] In the application of this embodiment, the low-concentration phosphoric acid circulated by the concentrated acid pump in step three is also the circulating acid. When the iron ion content of the circulating acid is less than 150 ppb, the circulating acid and the gas purifier are fully mixed in the pipeline mixer and then enter the arsenic removal reactor.

[0048] like Figure 2 The process flow chart is shown as follows:

[0049] Flowchart Description:

[0050] The production involves phosphorus melting section, oxidation section, purification section and water production section.

[0051] Liquid yellow phosphorus is transported from the yellow phosphorus transfer tank to the phosphorus combustion reaction tower spray gun through the yellow phosphorus transfer pump for quantitative combustion, atomized with compressed air and burned with the support of secondary air to generate P2O5 gas. The by-product steam enters the steam drum above the phosphorus combustion reaction tower, and the steam is then supplied to the production insulation and power generation equipment through the sub-cylinder. Under the action of the exhaust fan suction force, the P2O5 gas enters the hydration absorption tower, hydrates with the sprayed dilute phosphoric acid in the tower, and is absorbed to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through the semi-finished product filter, then enters the 3# transfer tank, and is then transported to the 7# adjustment tower for degassing. The degassed phosphoric acid is transported to the finished product tower through a precision filter.

[0052] Embodiment 2:

[0053] In the yellow phosphorus washing tank, the liquid yellow phosphorus is washed with circulating water for 1 hour by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0054] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0055] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 75 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0056] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 50 to 60 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0057] Embodiment three:

[0058] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0059] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0060] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 75 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0061] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 50 to 60 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0062] Embodiment 4:

[0063] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 3 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0064] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0065] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 75 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0066] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 50 to 60 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0067] Embodiment five:

[0068] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0069] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0070] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 70 and 75°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0071] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 60 to 70 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0072] Embodiment six:

[0073] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0074] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0075] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 65 and 70°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0076] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 60 to 70 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0077] Embodiment seven:

[0078] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0079] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0080] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 60 and 65°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0081] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 60 to 70 kPa in the pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0082] Embodiment eight:

[0083] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0084] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0085] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 65 and 70°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0086] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 70 to 80 kPa in the pipeline mixer and then enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0087] Embodiment nine:

[0088] In a yellow phosphorus washing tank, liquid yellow phosphorus is washed with circulating water for 2 hours by a submerged pump, and then the yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, and a phosphorus spray gun is used to assist the combustion, and the air pressure of the phosphorus spray gun is controlled to be stable between 400 kPa and 500 kPa;

[0089] The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank.

[0090] Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 65 and 70°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71;

[0091] When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with the gas purifier at a pressure of 80 to 90 kPa in the pipeline mixer and then enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

[0092] like Figure 2-Figure 6 As shown, the detailed selection process of the antimony removal technology route of this scheme is as follows:

[0093] like Figure 2The process route is shown in 1: the circulating acid goes to the arsenic removal reaction tower and reacts with hydrogen sulfide before passing through the pipeline mixer and entering the tower. After that, it is mixed by baffle flow and then enters the 1# sedimentation pot. The sedimentation pot enters from the bottom and exits from the top. Then it enters the 2# sedimentation pot. The 2# sedimentation pot does not have a backlog of liquid level. Finally, it enters the semi-finished product filter to filter out arsenide and other impurities. Then it goes to the transfer tank and is degassed by the degassing tower. After the subsequent processing, the finished product is obtained.

[0094] like Figure 3 The process route 2 is shown as follows: the circulating acid goes to the arsenic removal reaction tower and reacts with hydrogen sulfide before passing through the pipeline mixer and entering the tower. After that, it is mixed by baffle flow and then enters the 1# sedimentation pot. The sedimentation pot enters from the bottom and exits from the top. Then, it enters the 2# and 3# sedimentation pots. The liquid level of the 2# and 3# sedimentation pots is overpressured by 60%. Finally, it enters the semi-finished product filter to filter out arsenide and other impurities. Then, it goes to the transfer tank and is degassed by the degassing tower. After the subsequent processing, the finished product is obtained.

[0095] like Figure 4 The process route 3 is shown as follows: the yellow phosphorus is washed with water in the transfer tank to remove part of the antimony, and then oxidized and hydrated to obtain a circulating acid with a relatively low antimony content. The circulating acid reacts with hydrogen sulfide before the arsenic removal reaction tower, passes through a pipeline mixer, enters the horizontal tower, and is mixed by baffle flow. Then, it enters the 1# precipitation pot, enters the bottom and exits the top of the precipitation pot, and then enters the 2# and 3# precipitation pots. The liquid level of the 2# and 3# precipitation pots is overloaded by 60%, and finally enters the semi-finished product filter to filter out arsenide and other impurities. Then, it goes to the transfer tank and is degassed in the degassing tower. After entering the temporary storage tank, a part of it is returned to the front of the pipeline mixer to be combined with the arsenic-containing acid for secondary arsenic removal, and finally the finished product is obtained through post-processing.

[0096] like Figure 5 The process route 4 is shown as follows: the yellow phosphorus is washed with water in the transfer tank to remove part of the antimony, and then oxidized and hydrated to obtain a circulating acid with a relatively low antimony content. The circulating acid reacts with hydrogen sulfide before the arsenic removal reaction tower, passes through a pipeline mixer, enters the horizontal tower, and is mixed by baffle flow. Then, it enters the 1# precipitation pot, enters the bottom of the precipitation pot and exits the top, and then enters the 2# precipitation pot. From the bottom of the 2# precipitation pot, it goes to the centrifuge, and after passing through the centrifuge, it is sent back to the 3# precipitation pot. The liquid level of the 2# and 3# precipitation pots is overloaded by 60%, and finally enters the semi-finished product filter to filter out arsenide and other impurities, then goes to the transfer tank and is degassed through a degassing tower. After entering the temporary storage tank, a part of it is returned to the front of the pipeline mixer and combined with arsenic-containing acid for secondary arsenic removal, and finally the finished product is obtained through post-processing.

[0097] like Figure 6The process route 5 is shown as follows: the yellow phosphorus is washed with water in the transfer tank to remove part of the antimony, and then oxidized and hydrated to obtain a circulating acid with a relatively low antimony content. The circulating acid reacts with hydrogen sulfide before entering the arsenic removal reaction tower, passes through a pipeline mixer, enters the tower, and is mixed by baffle flow. Then, it enters the 1# precipitation pot, and then enters the 2# precipitation pot. The 1# and 2# precipitation pots enter from the bottom and exit from the top, and go from the top of the 2# precipitation pot to the upper feed port of the 3# precipitation pot. The liquid level of the 3# precipitation pot is overloaded by 60%, and finally enters the semi-finished product filter to filter out arsenide and other impurities, then goes to the transfer tank to be degassed through the degassing tower, and then the finished product is obtained through post-processing.

[0098] like Figure 7 The production situation of low antimony electrical acid is shown in the figure and table below:

[0099]

[0100]

[0101] Through the following technical improvements:

[0102] 1. Adjust the acid temperature at the bottom of the hydration tower to about 70° and keep the liquid level of the hydration tower at 50%.

[0103] 2. The gas flow rate of arsenic and hydrogen sulfide removal is increased from 4Kpa / min to 8Kpa / min.

[0104] 3. Install a pipeline mixer in front of the reaction tower to make the hydrogen sulfide mix more evenly.

[0105] 4. The 1# sedimentation pot is technically modified to have acid entering from the bottom and acid exiting from the top and entering the 2# sedimentation pot with a backlog of 60%, thus extending the reaction time.

[0106] 5. Partial secondary arsenic removal.

[0107] 6. Reduce the acid production flow rate from the original 20t / h to 12t / h.

[0108] 7. Reduce impurities and reduce antimony in circulating acid by rinsing yellow phosphorus with depressurized phosphorus water.

[0109] It can be seen from the above test data that from process route one to process route five, through continuous improvement, the antimony ion content of the final phosphate produced has dropped from more than 1470ppb to about 700ppb, which greatly improves the product quality of thermal phosphoric acid and reduces the unit consumption of purifiers to a certain extent.

[0110] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for producing phosphoric acid with a low content of antimony ions, characterized in that: Liquid yellow phosphorus is transported to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas. The phosphorus pentoxide gas is transported to a hydration absorption tower by negative pressure and absorbed by low-concentration phosphoric acid circulated by a concentrated acid pump to generate crude phosphoric acid. When the specific gravity of the phosphoric acid in the hydration absorption tower meets the process requirements, the arsenic removal operation of the purification process is carried out. The crude phosphoric acid is fully mixed with the gas purifier and then enters the arsenic removal reactor, precipitator and arsenic removal filter, and finally enters the degassing tower to remove excess gas purifier. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

2. The method for producing phosphoric acid with a low antimony ion content according to claim 1, characterized in that: The specific steps of the method are as follows: Step 1: transporting the unwashed yellow phosphorus to a phosphorus burning furnace to react with oxygen in the air to generate phosphorus pentoxide gas, using a phosphorus spray gun to assist combustion, and controlling the air pressure of the phosphorus spray gun to be stable between 400 kPa and 500 kPa; Step 2: The phosphorus pentoxide gas after combustion is transported to the hydration absorption tower by negative pressure, and is absorbed by the low-concentration phosphoric acid circulated by the concentrated acid pump to generate crude phosphoric acid. The crude phosphoric acid reacts with hydrogen sulfide and is filtered through a semi-finished product filter before entering the transfer tank; Specifically, the wall temperature of the hydration absorber needs to be controlled below 40°C, the inlet temperature of the primary venturi below 70°C, the inlet temperature of the circulating cooling water below 38°C, the bottom acid temperature of the hydration absorber is controlled between 65 and 80°C, and the specific gravity of the acid in the hydration absorber is controlled between 1.60 and 1.71; Step 3: When the specific gravity of phosphoric acid in the hydration absorption tower meets the process requirements, arsenic removal operation is carried out. The crude phosphoric acid is fully mixed with a gas purifier at a pressure of 50 to 90 kPa in a pipeline mixer and enters the arsenic removal reactor, then enters the precipitator, and then overflows from the precipitator to the arsenic removal filter, and then enters the degassing tower to remove excess gas purifier. The degassing pressure is controlled between 2 kPa and 5 kPa. After degassing, it enters the adjustment tower to adjust the concentration to obtain the finished product.

3. The method for producing phosphoric acid with a low antimony ion content according to claim 2, characterized in that: In step 1, a compressed air bag is used and the air is drained once every hour to ensure that there is no condensed water or other iron filings impurities in the air.

4. The method for producing phosphoric acid with a low antimony ion content according to claim 1, characterized in that: The phosphorus content of the yellow phosphorus is 99.9% or more, and the appearance is light yellow or transparent waxy solid.

5. The method for producing phosphoric acid with a low antimony ion content according to claim 2, characterized in that: The transfer tank in step 2 washes the semi-finished yellow phosphorus product, the temperature of the yellow phosphorus and the washing water is controlled between 60 and 75° C., and the washing time is not less than 2 hours.

6. The method for producing phosphoric acid with a low antimony ion content according to claim 2, characterized in that: In the step 1, by-product steam is generated, and the by-product steam enters the steam drum above the phosphorus burning furnace, and the steam is then passed through the cylinder for use in the production of heat preservation and power generation devices.

7. The method for producing phosphoric acid with a low antimony ion content according to claim 1, characterized in that: In the hydration absorption tower in step 2, process water is added to carry out hydration reaction, and the process water uses demineralized water that has been treated with anion and cation exchange.

8. The method for producing phosphoric acid with a low antimony ion content according to claim 7, characterized in that: The conductivity of the desalted water is less than 30 us / cm, the sodium ion is less than 100 ppb, and the iron ion is less than 30 ppb.

9. The method for producing phosphoric acid with a low antimony ion content according to claim 2, characterized in that: The low-concentration phosphoric acid circulated by the concentrated acid pump in step three is also the circulating acid. When the iron ion content of the circulating acid is less than 150 ppb, the circulating acid and the gas purifier are fully mixed in the pipeline mixer and then enter the arsenic removal reactor.

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