CN111646443B - Wet-process phosphoric acid desulfurization method and system - Google Patents
Wet-process phosphoric acid desulfurization method and system Download PDFInfo
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- CN111646443B CN111646443B CN202010715306.0A CN202010715306A CN111646443B CN 111646443 B CN111646443 B CN 111646443B CN 202010715306 A CN202010715306 A CN 202010715306A CN 111646443 B CN111646443 B CN 111646443B
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- C01B25/00—Phosphorus; Compounds thereof
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- C01B25/18—Phosphoric acid
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Abstract
The embodiment of the invention provides a wet-process phosphoric acid desulfurization method and a wet-process phosphoric acid desulfurization system, and belongs to the technical field of phosphoric acid production. The method comprises the following steps: adding phosphorite sand with the size of 1-20mm into wet phosphoric acid obtained by sulfuric acid, phosphorite pulp and acid return reaction, stirring and reacting for 5-90 days at the temperature of 10-95 ℃, standing and settling, wherein supernatant liquid is desulphurized phosphoric acid, lower-layer slurry is washed and then is sent to ball mill to serve as a raw material of phosphorite pulp, washing liquid is mixed into acid return, and the dosage of phosphorite sand is 4-100 times of the molar quantity of sulfuric acid. Although the surface area of the ore sand is smaller than that of the ore powder, the ore sand can also remove SO 3 The concentration is reduced to 0.3-0.6%, the desulfurization time is only slightly increased compared with the prior art, but the sedimentation treatment time can be obviously reduced (or special sedimentation is not needed), and the total treatment time of phosphoric acid is 10-30% less than that of the conventional method. The solid content of the desulphurized phosphoric acid is not obviously increased, and the washing water and solid materials after desulfurization, sedimentation and washing are easy to treat.
Description
Technical Field
The invention belongs to the technical field of phosphoric acid production, and particularly relates to a desulfurization method of wet-process phosphoric acid.
Background
Phosphoric acid (H) 3 PO 4 ) Can be used as a raw material for producing compound fertilizer. In the related art, sulfate ions (SO 4 2- ) The content is generally high (about 3.50%) and phosphorus pentoxide (P) 2 O 5 ) The content of (2) is not relatively too high (can reach about 21.5%). Phosphoric acid having the above characteristics (high sulfate ion content, low phosphorus pentoxide content) causes a decrease in quality of the compound fertilizer (such as total content of active ingredients). In order to ensure the quality of the phosphate fertilizer, the production process of phosphoric acid needs to be adjusted; alternatively, the phosphoric acid with high sulfate ion content is subjected to desulfurization and concentration treatment.
In the prior art, phosphoric acid is usually desulfurized by adding a phosphoric acid slurry or a phosphoric acid ore powder to wet phosphoric acid.
The patent of application number CN201520918660.8 discloses a wet process phosphoric acid desulfurization device, including wet process phosphoric acid metering pump, phosphorite pulp metering pump, desulfurization reaction tank is connected to wet process phosphoric acid metering pump, phosphorite pulp metering pump, and the desulfurization reaction tank passes through the slurry pump and connects the sedimentation tank, and the desulfuric acid storage tank is connected to the sedimentation tank, be equipped with the stirring leaf in the desulfurization reaction tank, the sedimentation tank bottom is equipped with the slag notch.
The patent of application number CN201822000884.7 discloses a dilute phosphoric acid desulfurization production line for improving industrial grade monoammonium phosphate output, including the ore pulp tank that contains concentrate pulp, hold dilute phosphoric acid's dilute acid ageing tank and desulfurization tank, be provided with the ore pulp pump on the ore pulp tank, the ore pulp pump is through first transfer line and desulfurization tank intercommunication, be provided with ageing tank pump on the dilute acid ageing tank, ageing tank pump is through second transfer line and desulfurization tank intercommunication, is provided with the agitator in the desulfurization tank, one side of desulfurization tank is close to the below and is provided with the sediment acid pump, and the sediment acid pump is connected to the desulfurization clarifying tank through the third transfer line, the inside rotation harrow that is provided with of desulfurization clarifying tank, desulfurization clarifying tank bottom is provided with the desilting acid pump, and the desilting acid pump gets into the reaction tank through the recovery pipeline, one side of desulfurization clarifying tank is close to the below and is provided with the desulfurating acid transfer pump, and the desulfurating acid transfer pump is connected to monoammonium phosphate production line through the fourth transfer line.
A method for producing monopotassium phosphate by wet-process phosphoric acid according to the patent application No. CN 201210581157.9, comprising the following steps:
(1) Adding phosphate rock powder into wet phosphoric acid, reacting at 30-70 ℃ for 1-3 hours, separating solid from liquid, and obtaining filtrate to obtain the desulphurized phosphoric acid.
(2) Concentrating the desulphurized phosphoric acid prepared in the step (1), adding potassium chloride to prepare a mixed solution, reacting at the temperature of 60-100 ℃, and obtaining a mixture after the reaction is finished.
(3) And (3) adding a pH regulator into the mixture prepared in the step (2) to regulate the pH value to 4.7-7.0, and carrying out solid-liquid separation to obtain filtrate.
(4) And (3) adding phosphoric acid into the filtrate obtained in the step (3), and adjusting the pH value to 3.0-4.7 to obtain a mixed solution.
(5) And (3) cooling and crystallizing the mixed solution prepared in the step (4), then carrying out solid-liquid separation, taking crystals, and drying to obtain the potassium dihydrogen phosphate.
The desulfurization by using the phosphorus ore pulp can additionally introduce water, which is unfavorable for the subsequent treatment (such as concentration); the solid content of phosphoric acid (the solid content is improved by about 0.3-0.8%) is obviously increased when the phosphorite powder or the phosphorite pulp is used for desulfurization treatment, and filtration is usually needed, but if sedimentation treatment is used, the solid content of phosphoric acid cannot be effectively reduced, and the phosphoric acid is sticky. In the prior art, a small amount of calcium phosphate crystals in the desulfurized phosphoric acid and the rest of phosphate slurry or phosphate rock powder form a sticky paste, the filtering is very difficult (if a rotary disc vacuum filter is needed), and the cost is high. Meanwhile, the acidic waste generated by desulfurization is inconvenient to transport and process (such as high acidity and easy corrosion of a ball mill).
Disclosure of Invention
The embodiment of the invention provides a method and a system for desulfurizing wet-process phosphoric acid, which comprehensively consider various factors, find out the optimal method and conditions, reduce the processing time of the wet-process phosphoric acid to improve the yield on the premise of not increasing the solid content of the wet-process phosphoric acid when the wet-process phosphoric acid is desulfurized, reduce the transportation and processing difficulties, and avoid larger technical improvement to control the cost as much as possible. The technical scheme is as follows:
in one aspect, an embodiment of the present invention provides a method for desulfurizing wet-process phosphoric acid, including: adding phosphorite sand with the size of 1-20mm into wet phosphoric acid obtained by sulfuric acid, phosphorite slurry and acid reaction, stirring and reacting for 5-90 days at the temperature of 10-95 ℃, standing and settling, wherein supernatant liquid is desulphurized phosphoric acid, lower slurry is washed with water and then is sent to ball mill to serve as a raw material of phosphorite slurry, washing liquid is mixed into acid return, and the consumption of phosphorite sand is 4-100 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
Preferably, the size of the phosphated sand in the embodiment of the invention is 3-6mm.
Preferably, the temperature of the stirring reaction in the embodiment of the invention is 80-90 ℃, and the time of the stirring reaction is 16-20 hours.
Preferably, the amount of the phosphated sand in the embodiment of the invention is 4-10 times of the molar amount of sulfuric acid in the wet phosphoric acid.
Specifically, the method provided in the embodiment of the invention specifically includes: adding phosphate rock sand with the size of 3-10mm into wet phosphoric acid obtained by sulfuric acid, phosphorus ore pulp and acid return reaction, stirring and reacting for 16-20 hours at the temperature of 80-90 ℃, standing and settling, wherein supernatant liquid is desulphurized phosphoric acid, washing lower-layer slurry, then sending ball milling to serve as a raw material of the phosphorus ore pulp, and merging washing liquid into acid return, wherein the consumption of the phosphate rock sand is 30-50 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
Specifically, in another implementation manner of the present patent, the method provided by the embodiment of the present invention specifically includes: adding the phosphate sand and the wet-process phosphoric acid into a wet-process phosphoric acid storage tank, preserving at room temperature, intermittently stirring, taking out supernatant fluid after a period of time to obtain desulfurized phosphoric acid, continuously adding the wet-process phosphoric acid into the wet-process phosphoric acid storage tank, repeating the above processes for a plurality of times, washing the lower-layer slurry for 1-3 months, sending the lower-layer slurry to ball mill to serve as a raw material of phosphate pulp, and merging washing liquid into return acid; the size of the phosphorite sand is 10-20mm, and the dosage of the phosphorite sand is 100-200 times of the molar quantity of sulfuric acid in the wet-process phosphoric acid.
Further, in the invention, after primary crushing, part or all of the ore sand is screened, the ore sand with the size of 1-20mm is sent into wet phosphoric acid for desulfurization, the residual ore sand after primary crushing and other ore sand obtained by screening are crushed for the second time to obtain rock phosphate powder, and the rock phosphate powder and process water are ball-milled to obtain the phosphate pulp.
Further, in another embodiment of the invention, after the phosphorite is crushed, part or all of the ore sand is screened, the phosphorite sand with the size of 1-20mm is sent into wet phosphoric acid for desulfurization, and the phosphorite sand with the size of less than 1mm, the crushed residual ore sand and process water are subjected to ball grinding to obtain phosphorite pulp.
On the other hand, the embodiment of the invention also provides a desulfurization system of wet-process phosphoric acid, which comprises a screening device, a water washing device, a crushing device, a ball milling device, a thickening device, a synthesis reaction kettle, a filtering device, a desulfurization reaction kettle and a sedimentation tank which are sequentially arranged; the acid return outlet of the filtering device is connected with the feed inlet of the synthesis reaction kettle through a pipeline; the feed inlet of the screening device is connected with the discharge outlet of the crushing device through a conveying belt, the discharge outlet which meets the desulfurization granularity requirement is connected with the feed inlet of the desulfurization reaction kettle through the conveying belt, and the discharge outlet which does not meet the desulfurization granularity requirement is connected with the crushing device or the ball milling device through the conveying belt; the washing device is connected with a slurry outlet of the settling tank through a pipeline, a washing liquid outlet of the washing device is connected with a feed inlet of the synthesis reaction kettle or an acid return storage tank through a pipeline, and a solid material outlet of the washing device is connected with a feed inlet of the ball milling device through a conveying belt.
Wherein, the desulfurization reaction kettle in the embodiment of the invention is a reaction kettle or a wet-process phosphoric acid storage tank; when the reactor is a reaction kettle, a stirrer and a heating structure are arranged in the reactor; in the case of wet phosphoric acid storage tank, a stirrer is arranged in the wet phosphoric acid storage tank.
Further, the crushing device in the embodiment of the invention comprises a primary crushing structure capable of crushing to obtain 1-20mm phosphate sand and a secondary crushing structure capable of crushing to obtain phosphate rock powder, wherein a discharge port of the primary crushing structure is output in two paths through a conveying belt, one path of the discharge port is output to a feed inlet of the secondary crushing structure, and the other path of the discharge port is output to a feed inlet of the screening device; other discharge gates of screening plant pass through the conveyer belt and are connected with the feed inlet of regrinding structure, regrinding structure's discharge gate passes through the conveyer belt and is connected with ball-milling device, primary crushing structure and regrinding structure all include at least one rubbing crusher.
Specifically, the primary crushing structure in the embodiment of the invention is a jaw crusher, and the secondary crushing structure is a cone crusher.
The technical scheme provided by the embodiment of the invention has the beneficial effects that: the embodiment of the invention provides a wet-process phosphoric acid desulfurization method and a wet-process phosphoric acid desulfurization system, which have the following advantages:
1. SO in wet phosphoric acid can be removed 3 The concentration is reduced to 0.3-0.6%, which is consistent with the prior art.
2. And special equipment is not needed for filtering, so that the labor intensity and the cost are reduced.
3. The solid content of the wet-process phosphoric acid is not increased obviously.
4. The solid material (with lower acidity) obtained by treatment is easy to transport and treat (can be directly sent into a ball mill).
5. The phosphorite sand used for desulfurization can be obtained from the existing crushing device, and the investment of technical improvement is low.
6. Although the desulfurization time is slightly longer than that of mineral powder and ore pulp, the total treatment time of phosphoric acid is 10-30% less than that of the conventional method.
Drawings
FIG. 1 is a schematic block diagram of a wet process phosphoric acid desulfurization system provided by an embodiment of the present invention;
FIG. 2 is a schematic block diagram of a comminution apparatus according to an embodiment of the present invention;
FIG. 3 is a schematic block diagram of another wet process phosphoric acid desulfurization system provided in an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent.
Example 1
Referring to fig. 1 to 3, example 1 provides a desulfurization system for wet phosphoric acid, which comprises a pulverizing device, a ball milling device, a thickening device, a synthesis reaction kettle, a filtering device, a desulfurization reaction kettle, a sedimentation tank, etc., which are sequentially arranged (connected by a conveyer belt or a pipeline (on which a valve, a pump, etc. are arranged as needed) according to actual needs; the crushing device is formed by comprising a plurality of crushers (different crushing sizes) connected in series, such as jaw crushers, cone crushers and the like. The ball milling device is a ball mill (a rotational flow structure can be arranged according to the requirement). The thickening device is a thickening tank. The synthesis reaction vessel comprises at least one reaction vessel, typically consisting of a plurality of reaction vessels, sulfuric acid, a slurry of phosphorus and return acid typically being reacted in a first reaction vessel, the subsequent reaction vessel being supplemented with sulfuric acid, typically with a slight excess (of around 3%) of sulfuric acid to ensure the yield of phosphoric acid. The filter means is typically a disc filter. The desulfurization reaction kettle is a conventional reaction kettle. The settling tank is of a conventional structure, and can be specifically an inclined plate settling tank and the like. An intermediate storage tank can be arranged between the structures according to the requirements, for example, a phosphorite slurry storage tank is arranged between the thickening device and the synthesis reaction kettle, and a wet-process phosphoric acid storage tank is arranged between the filtering device and the desulfurization reaction kettle. The supernatant outlet at the upper part of the settling tank outputs (e.g. overflows) the desulphurized phosphoric acid. The acid return outlet (such as the output of the primary filtering area) of the filtering device is connected with the feed inlet of the synthesis reaction kettle through a pipeline. The structure is basically identical with that of the existing wet-process phosphoric acid desulfurization system, and the difference is that: the desulfurization system provided by the embodiment also comprises a screening device and a washing device; the feeding hole of the sieving device is connected with the discharging hole (which can be connected with the ball milling device) of the crushing device (part of the crusher capable of crushing to obtain phosphorite sand with the size of 1-20mm (the size of 1-20mm is smaller than or equal to the size of 20 and the like) through the conveying belt, the discharging hole which accords with the desulfurization granularity requirement (1-20 mm) is connected with the feeding hole of the desulfurization reaction kettle through the conveying belt, the discharging hole which does not accord with the desulfurization granularity requirement is connected with the crushing device or the ball milling device through the conveying belt (the conditions can be divided, if the material output by the crushing device is smaller than or equal to 20mm, the fine material is conveyed according to the feeding requirement of the ball milling device, if the feeding requirement of the ball milling device is larger than 1mm, the fine material is conveyed to the ball milling device, otherwise the crushing device is conveyed to the ball milling device after being crushed again, and the fine material is conveyed to the ball milling device after being crushed again according to the feeding requirement of the ball milling device, and the feeding requirement of the coarse material is more than 1mm, otherwise the crushing device is conveyed to the ball milling device). The washing device is connected with a slurry outlet of the settling tank (bottom) through a pipeline (a pump is arranged according to the requirement), a washing liquid outlet (an overflow port or the bottom) of the washing device is connected with a feed inlet or an acid return storage tank of the synthesis reaction kettle through a pipeline to recycle washing liquid as acid return, and a solid material outlet of the washing device is connected with a feed inlet of the ball milling device through a conveying belt (of course, due to small quantity, manual transportation can be adopted) to recycle the washing liquid as phosphorite slurry raw material. The washing device can be a common washing tank, solid materials after washing are output by a conveying belt, washing liquid is discharged from the bottom of the washing device, and tap water is added into the washing device for washing.
Wherein, the desulfurization reaction kettle in the embodiment of the invention is a reaction kettle or a wet-process phosphoric acid storage tank; when the reaction kettle is used (a clear liquid outlet is connected with a wet-process phosphoric acid storage tank), a stirrer, a heating structure and the like are arranged in the reaction kettle; in the case of a wet phosphoric acid storage tank, a stirrer and the like are arranged in the wet phosphoric acid storage tank.
Further, referring to fig. 2, the crushing device in the embodiment of the invention comprises a primary crushing structure capable of crushing to obtain 1-20mm phosphate sand and a secondary crushing structure capable of crushing to obtain phosphate rock powder, wherein a discharge port of the primary crushing structure is output in two paths through a conveying belt, one path of the discharge port is output to a feed port (not output) of the secondary crushing structure, the other path of the discharge port is output to a feed port of the screening device, and the output of the two paths of the discharge port can be controlled through a discharge door on the discharge port of the primary crushing structure. Other discharge ports of the screening device are connected with a feed inlet of the secondary crushing structure through a conveying belt, the discharge port of the secondary crushing structure is connected with the ball milling device through a conveying belt, and the primary crushing structure and the secondary crushing structure all comprise at least one crusher.
Specifically, the primary crushing structure in the embodiment of the invention is a jaw crusher (consistent with the prior art), and generally 1-20mm of phosphate ore sand can be obtained; the secondary crushing structure is a cone crusher (consistent with the prior art). That is, the structure of the conventional crushing device is not required to be adjusted, and the phosphate rock sand meeting the requirements can be obtained by only adding the screening device and the conveying belt.
Example 2
Example 2 provides a method for desulfurizing wet-process phosphoric acid, employing the desulfurization system disclosed in example 1. The method comprises the following steps: adding 1-20mm phosphate ore sand into wet phosphoric acid obtained by sulfuric acid, phosphorus ore pulp and return acid reaction, stirring and reacting for 5-90 days at 10-95 ℃, standing and settling, wherein supernatant liquid is desulphurized phosphoric acid, washing lower-layer slurry, then sending to ball mill to be used as a raw material of the phosphorus ore pulp, merging washing liquid into return acid (can also be directly sent to a synthesis reaction kettle for synthesizing the wet phosphoric acid, and adjusting the concentration of the return acid according to the requirement, and controlling the concentration of the return acid to be 14-16 percent, wherein the consumption of the phosphate ore sand (based on the molar quantity of calcium) is 4-100 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
Preferably, the size of the phosphated sand in the embodiment of the invention is 3-6mm.
Preferably, the temperature of the stirring reaction in the embodiment of the invention is 80-90 ℃, and the time of the stirring reaction is 16-20 hours.
Preferably, the amount of the phosphated sand in the embodiment of the invention is 4-10 times of the molar amount of sulfuric acid in the wet phosphoric acid.
Specifically, the method provided in the embodiment of the invention specifically includes: adding phosphate rock sand with the size of 3-6mm into wet phosphoric acid obtained by sulfuric acid, phosphate ore pulp and acid return reaction, stirring (preferably continuously stirring) at 80-90 ℃ for reaction for 16-20 hours, standing for settling, wherein supernatant liquid is desulphurized phosphoric acid, lower slurry is washed with water and then is sent to ball mill to serve as a raw material of the phosphate ore pulp, washing liquid is incorporated into acid return, and the dosage of the phosphate ore sand is 4-10 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
Specifically, in another implementation manner of the present patent, the method provided by the embodiment of the present invention specifically includes: adding the phosphate sand and the wet phosphoric acid into a wet phosphoric acid storage tank (according to storage requirements), preserving at room temperature, intermittently stirring (such as stirring for 0.5-1 hour every 8-12 hours, not requiring high) for a period of time (such as 5-10 days or taking according to acid requirements), taking out supernatant to obtain desulphurized phosphoric acid, continuously adding the wet phosphoric acid into the wet phosphoric acid storage tank, repeating the above processes for a plurality of times, taking out the lower slurry from the bottom after 1-3 months, washing with water, sending to ball mill to serve as a raw material of phosphate slurry, and mixing the washing liquid into return acid. Wherein the size of the phosphorite sand is 10-20mm, and the dosage of the phosphorite sand is 30-50 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
Further, in the invention, after primary crushing (such as jaw crusher) of phosphorite, part or all of ore sand is screened, phosphorite sand with the size of 1-20mm is sent into wet phosphoric acid for desulfurization, residual ore sand (if any) after primary crushing and other ore sand obtained by screening are subjected to secondary crushing (such as cone crusher) to obtain phosphorite powder, and phosphorite powder and process water are subjected to ball milling to obtain phosphorite pulp (after ball milling, concentration and magnesium removal treatment).
Further, in another embodiment of the invention, after the phosphorite is crushed (ore sand with the size less than or equal to 20mm can be obtained), part or all of the ore sand is screened, phosphorite sand with the size of 1-20mm is sent to wet phosphoric acid for desulfurization, phosphorite with the size less than 1mm and the rest of the crushed ore sand (if any) can be sent to be continuously crushed) are ball-milled with process water (the feeding requirement is more than 20 mm) to obtain phosphorite pulp.
Verification example 1
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration of 3.5%) and 6mm size of phosphorus ore sand (the dosage is 5 times of the molar quantity of sulfuric acid), the desulfurization temperature is 85 ℃, and SO is contained in the reaction solution 3 When the concentration is less than 0.6%, the desulfurization time is 12.5 hours, the obtained product is sent into a sedimentation tank for sedimentation, the sedimentation time is 3 hours, the obtained product overflows to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is detected to be 5.4%, the total time of phosphoric acid treatment is 15.5 hours,the lower slurry is washed with water and then is sent to ball milling to be used as a raw material of phosphorus ore pulp (the treated solid material is obviously granular after being washed with water and meets the ball milling requirement), and the washing liquid is incorporated into return acid (the acid concentration is almost equal to the counter acid concentration).
Verification example 2
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration 3.5%) and powdered rock phosphate (the dosage of the rock phosphate is the same as that of verification example 1), the desulfurization temperature is 85 ℃, and SO is contained in the reaction solution 3 When the concentration is less than 0.6%, the desulfurization time is 11.5 hours, the obtained product is sent into a sedimentation tank for sedimentation (the lower-layer slurry is in a homogenized slurry state, the transportation is inconvenient and the acidity is strong), the sedimentation time is 6.5 hours, the obtained product overflows to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is 5.7% after detection, and the total phosphoric acid treatment time is 18 hours.
Verification example 3
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration 3.5%) and powdered rock phosphate (the dosage of the rock phosphate is the same as that of verification example 1), the desulfurization temperature is 85 ℃, and SO is contained in the reaction solution 3 When the concentration is less than 0.6%, the desulfurization time is 11.5 hours, the obtained product is sent into a vacuum disc filter press for filtering, the filtering time is 8 hours, the solid content of the desulfurized phosphoric acid detected is 5.1%, the filter residue on the filter disc is very difficult to clean, a large amount of labor, energy and water are consumed, the cleaned filter residue is inconvenient to process, and the total phosphoric acid treatment time is 19.5 hours.
Verification example 4
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration of 3.5%) and 0.5mm size of phosphorus ore sand (the dosage is 5 times of the molar quantity of sulfuric acid), the desulfurization temperature is 85 ℃, and SO is contained in the reaction solution 3 When the concentration is less than 0.6%, the desulfurization time is 12.0 hours, the obtained product is sent into a sedimentation tank for sedimentation, the sedimentation time is 6.5 hours, the obtained product overflows to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is detected to be 5.7%, the total time for sulfuric acid treatment is 18 hours, and the lower-layer slurry is in a homogenized slurry state, so that the lower-layer slurry is inconvenient to wash.
Verification example 5
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration 3.5%) and 35mm size of phosphorus ore sand (5 times of sulfuric acid mole amount) are reacted, desulfurization temperature is 85 deg.C, when reactingSO in liquid 3 When the concentration is less than 0.6%, the desulfurization time is 16 hours, the obtained product is sent into a sedimentation tank for sedimentation, the sedimentation time is 2 hours, the obtained product overflows to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is detected to be 5.4%, the total time of phosphoric acid treatment is 18 hours, the lower-layer slurry is washed (the applicant simultaneously finds that the particles of the lower-layer slurry are larger, and part of raw materials do not meet the feeding requirements of a common ball mill), and the washing liquid is mixed into the return acid.
Verification example 6
Wet process phosphoric acid (solid content 5.3%, SO) 3 Concentration of 3.5%) and 8mm size of phosphorus ore sand (the dosage is 5 times of the mole amount of sulfuric acid), the desulfurization temperature is 85 ℃, and SO is contained in the reaction solution 3 When the concentration is less than 0.6%, the desulfurization time is 12.5 hours, the obtained product is sent into a sedimentation tank for sedimentation, the sedimentation time is 3 hours, the obtained product overflows to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is detected to be 5.4%, the total time of phosphoric acid treatment is 15.5 hours, the lower-layer slurry is washed with water and then is sent to ball milling to be used as a raw material of phosphorus ore pulp (the treated solid material is obviously granular and meets the ball milling requirement after being washed with water), and the washing liquid is mixed into the return acid.
Verification example 7
Wet process phosphoric acid (solid content 5.3%, SO) 3 3.5% of concentration) and 6mm size of phosphate ore sand (the dosage is 5 times of the molar quantity of sulfuric acid), the desulfurization temperature is 85 ℃, the desulfurization time is 36 hours, the phosphate ore sand is sent into a settling tank for settling, the settling time is 4 hours, the overflow is carried out to obtain the desulfurized phosphoric acid, the solid content of the desulfurized phosphoric acid is 5.4% after detection, and SO in the phosphoric acid 3 The concentration is reduced to 0.3%; the lower slurry is washed with water and then is sent to ball milling to be used as a raw material of phosphorus ore pulp (the treated solid materials are obviously granular after being washed with water and meet the ball milling requirement), and the washing liquid is incorporated into return acid.
As can be seen from verification examples, the ore sand used in the method has smaller surface area than ore powder, but can also remove SO in wet phosphoric acid 3 The concentration is reduced to 0.3-0.6%, meanwhile, the desulfurization time is only slightly increased compared with the prior art, but the sedimentation treatment time can be obviously reduced, and the total treatment time of phosphoric acid is 10-30% less than that of the conventional method. The solid content of the desulphurized phosphoric acid is not obviously increased, and the washing water and solid materials after desulfurization, sedimentation and washing are easy to treat. The method of the patent is healdAccording to the result, when the wet-process phosphoric acid is desulfurized, the treatment time is reduced to improve the yield on the premise of not increasing the solid content of the wet-process phosphoric acid, meanwhile, the transportation and treatment difficulties are reduced, and the larger technical improvement to control the cost is avoided as much as possible.
Verification example 8 wet phosphoric acid (5.3% solids, SO) was added to a wet phosphoric acid tank 3 Concentration 3.5%), adding 15mm of phosphate sand, wherein the dosage of the phosphate sand is 35 times of the molar quantity of sulfuric acid in the wet-process phosphoric acid when the wet-process phosphoric acid is full (the phosphate sand is contained); and (3) preserving at room temperature, intermittently stirring, taking out supernatant after 7 days to obtain desulfurized phosphoric acid, continuously adding wet phosphoric acid into a wet phosphoric acid storage tank, repeating the process for a plurality of times, washing the lower slurry with water after 56 days, sending the lower slurry to ball milling to serve as a raw material of phosphorus ore pulp (the treated solid material is obviously granular after washing and meets the ball milling requirement), and mixing the washing liquid into return acid. The solid content of wet phosphoric acid separated each time was detected to be 5.3% (SO) 3 Concentration of 0.5%), 5.3% (SO) 3 Concentration of 0.5%), 5.3% (SO) 3 Concentration of 0.5%), 5.3% (SO) 3 Concentration of 0.5%), 5.3% (SO) 3 Concentration of 0.5%), 5.4% (SO) 3 Concentration of 0.5%), 5.4% (SO) 3 Concentration of 0.5%) and 5.4% (SO) 3 Concentration was 0.5%).
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the invention are intended to be included within the scope of the invention.
Claims (9)
1. A method for desulfurizing phosphoric acid by a wet process, comprising: adding phosphorite sand with the size of 1-20mm into wet phosphoric acid obtained by sulfuric acid, phosphorite pulp and acid return reaction, stirring and reacting for 5-90 days at the temperature of 10-95 ℃, standing and settling, wherein supernatant liquid is desulphurized phosphoric acid, lower-layer slurry is washed and then is sent to ball mill to serve as a raw material of phosphorite pulp, washing liquid is mixed into acid return, and the consumption of phosphorite sand is 4-100 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
2. The method for desulfurizing phosphoric acid by wet process according to claim 1, characterized in that it comprises in particular: adding phosphate rock sand with the size of 3-10mm into wet phosphoric acid, stirring at 80-90 ℃ for reaction for 16-20 hours, standing for settling, collecting supernatant liquid which is desulphurized phosphoric acid, washing lower slurry, sending ball milling to serve as a raw material of phosphate slurry, and mixing washing liquid into return acid, wherein the consumption of the phosphate rock sand is 4-10 times of the molar quantity of sulfuric acid in the wet phosphoric acid.
3. The method for desulfurizing phosphoric acid by wet process according to claim 1, characterized in that it comprises in particular: adding the phosphate sand and the wet-process phosphoric acid into a wet-process phosphoric acid storage tank, preserving at room temperature, intermittently stirring, taking out supernatant fluid after a period of time to obtain desulfurized phosphoric acid, continuously adding the wet-process phosphoric acid into the wet-process phosphoric acid storage tank, repeating the above processes for a plurality of times, washing the lower-layer slurry for 1-3 months, sending the lower-layer slurry to ball mill to serve as a raw material of phosphate pulp, and merging washing liquid into return acid; the size of the phosphorite sand is 10-20mm, and the dosage of the phosphorite sand is 30-50 times of the molar quantity of sulfuric acid in the wet-process phosphoric acid.
4. The method for desulfurizing phosphoric acid by wet process according to claim 1, wherein after primary crushing, part or all of the ore sand is sieved, the ore sand with the size of 1-20mm is sent into phosphoric acid by wet process for desulfurizing, after secondary crushing, the residual ore sand after primary crushing and other ore sand obtained by sieving are crushed to obtain powder of the ore, and the powder of the ore sand is ball-milled with process water to obtain the phosphor pulp.
5. The method for desulfurizing phosphoric acid by wet process according to claim 1, wherein after the phosphoric ore is crushed, part or all of the ore is screened, the phosphoric ore with the size of 1-20mm is sent into phosphoric acid by wet process for desulfurizing, and the ore with the size of less than 1mm and the rest of the crushed ore are subjected to ball grinding with process water to obtain the ore slurry.
6. The wet-process phosphoric acid desulfurization system comprises a crushing device, a ball milling device, a thickening device, a synthesis reaction kettle, a filtering device, a desulfurization reaction kettle and a sedimentation tank which are sequentially arranged, wherein an acid return outlet of the filtering device is connected with a feed inlet of the synthesis reaction kettle through a pipeline; the system is characterized by further comprising a screening device and a water washing device; the feed inlet of the screening device is connected with the discharge outlet of the crushing device through a conveying belt, the discharge outlet which meets the desulfurization granularity requirement is connected with the feed inlet of the desulfurization reaction kettle through the conveying belt, and the discharge outlet which does not meet the desulfurization granularity requirement is connected with the crushing device or the ball milling device through the conveying belt; the washing device is connected with a slurry outlet of the settling tank through a pipeline, a washing liquid outlet of the washing device is connected with a feed inlet of the synthesis reaction kettle or an acid return storage tank through a pipeline, and a solid material outlet of the washing device is connected with a feed inlet of the ball milling device through a conveying belt; and the discharge hole meeting the desulfurization granularity requirement outputs the phosphate ore sand with the size of 1-20 mm.
7. The desulfurization system of wet-process phosphoric acid according to claim 6, wherein the desulfurization reaction kettle is a reaction kettle or a wet-process phosphoric acid storage tank; when the reactor is a reaction kettle, a stirrer and a heating structure are arranged in the reactor; in the case of wet phosphoric acid storage tank, a stirrer is arranged in the wet phosphoric acid storage tank.
8. The desulfurization system of wet-process phosphoric acid according to claim 6, wherein the crushing device comprises a primary crushing structure capable of crushing to obtain 1-20mm phosphate sand and a secondary crushing structure capable of crushing to obtain phosphate rock powder, wherein a discharge port of the primary crushing structure is output in two paths through a conveying belt, one path of the discharge port is output to a feed port of the secondary crushing structure, and the other path of the discharge port is output to a feed port of the screening device; other discharge gates of screening plant pass through the conveyer belt and are connected with the feed inlet of regrinding structure, regrinding structure's discharge gate passes through the conveyer belt and is connected with ball-milling device, primary crushing structure and regrinding structure all include at least one rubbing crusher.
9. The wet process phosphoric acid desulfurization system of claim 8, wherein the primary pulverizing structure is a jaw crusher and the secondary pulverizing structure is a cone crusher.
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