阅读说明：本技术 一种湿法磷酸的脱硫方法及系统 (Desulfurization method and system for wet-process phosphoric acid ) 是由 黄忠 曾舟华 何俊 黄河 张险峰 余莹 查炎华 易忠敏 于 2020-07-23 设计创作，主要内容包括：本发明实施例提供了一种湿法磷酸的脱硫方法及系统,属于磷酸生产技术领域。该方法包括：在硫酸、磷矿浆和返酸反应得到的湿法磷酸中加入大小为1-20mm的磷矿砂,于10-95℃条件下搅拌反应5小时-90天,静置沉清,上层清液为脱硫磷酸,下层料浆水洗后送去球磨作为磷矿浆的原料,洗液并入返酸中,磷矿砂的用量为硫酸摩尔量的4-100倍。矿砂虽然较矿粉的表面积小,但是其同样能将SO<Sub>3</Sub>浓度降低至0.3-0.6%,对于现有技术脱硫时间只稍微增加,但是沉降处理时间能明显降低(或无需专门沉降),磷酸的总处理时间较常规方法少10-30%。不会明显增加脱硫磷酸的固含量,同时经脱硫、沉降和水洗后的洗水与固料易于处理。(The embodiment of the invention provides a desulfurization method and a desulfurization system for wet-process phosphoric acid, belonging to the technical field of phosphoric acid production. The method comprises the following steps: adding 1-20mm phosphate ore sand into wet-process phosphoric acid obtained by reacting sulfuric acid, phosphate ore slurry and acid return, stirring and reacting for 5 hours-90 days at 10-95 ℃, standing and settling, wherein the supernatant is desulfurized phosphoric acid, the lower slurry is washed by water and then sent to be ball-milled to be used as a raw material of the phosphate ore slurry, and the washing liquid is merged into the acid return, and the using amount of the phosphate ore sand is 4-100 times of the molar weight of the sulfuric acid. The ore sand has smaller surface area than the ore powder, but can also remove SO 3 The concentration is reduced to 0.3-0.6%, the desulfurization time is only slightly increased for the prior art, but the settling treatment time can be obviously reduced (or special settling is not needed), and the total treatment time of the phosphoric acid is 10-30% less than that of the conventional method. The solid content of the desulfurized phosphoric acid can not be obviously increasedAnd meanwhile, the washing water and the solid materials after desulfurization, sedimentation and water washing are easy to treat.)

1. A method for desulfurizing wet-process phosphoric acid, comprising: adding 1-20mm phosphate ore sand into wet-process phosphoric acid obtained by reacting sulfuric acid, phosphate ore slurry and acid return, stirring and reacting for 5 hours-90 days at 10-95 ℃, standing and settling, wherein the supernatant is desulfurized phosphoric acid, the lower slurry is washed by water and then sent to be ball-milled to be used as a raw material of the phosphate ore slurry, and washing liquid is merged into the acid return, and the using amount of the phosphate ore sand is 4-100 times of the molar weight of sulfuric acid in the wet-process phosphoric acid.

2. The method for desulfurizing wet-process phosphoric acid according to claim 1, which specifically comprises: adding 3-10mm phosphate ore sand into wet-process phosphoric acid, stirring and reacting for 16-20 hours at 80-90 ℃, standing and settling, wherein the supernatant is desulfurized phosphoric acid, the lower slurry is washed with water and then sent to be ball-milled to be used as a raw material of phosphate ore pulp, and the washing liquid is merged into return acid, and the use amount of the phosphate ore sand is 4-10 times of the molar weight of sulfuric acid in the wet-process phosphoric acid.

3. The method for desulfurizing wet-process phosphoric acid according to claim 1, which specifically comprises: adding phosphate rock sand and wet-process phosphoric acid into a wet-process phosphoric acid storage tank, storing at room temperature, intermittently stirring, taking out supernatant 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 multiple times, after 1-3 months, taking lower-layer slurry, washing with water, and then sending the lower-layer slurry to ball milling to serve as a raw material of phosphate pulp, wherein washing liquor is merged into returned acid; the size of the phosphorite sand is 10-20mm, and the dosage of the phosphorite sand is 30-50 times of the molar weight of sulfuric acid in the wet-process phosphoric acid.

4. The desulfurization method of wet phosphoric acid according to claim 1, wherein after primary crushing of phosphate ore, part or all of the ore is sieved, the phosphate ore with a size of 1-20mm is sent to wet phosphoric acid for desulfurization, the remaining ore after primary crushing and other ore obtained by sieving are crushed again to obtain phosphate ore powder, and the phosphate ore powder is ball-milled with process water to obtain phosphate ore slurry.

5. The desulfurization method of wet phosphoric acid according to claim 1, wherein after the phosphate ore is crushed, part or all of the ore sand is sieved, the phosphate ore sand with the size of 1-20mm is sent to the wet phosphoric acid for desulfurization, and the phosphate ore sand with the size of less than 1mm and the rest of the crushed ore sand are ball-milled with process water to obtain phosphate ore slurry.

6. A desulfurization system for wet-process phosphoric acid comprises a crushing device, a ball milling device, a thickening device, a synthesis reaction kettle, a filtering device, a desulfurization reaction kettle and a settling tank which are arranged in sequence, 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 also comprising a screening device and a water washing device; the feed port of the screening device is connected with the discharge port of the crushing device through a conveyer belt, the discharge port meeting the requirement of desulfurization particle size is connected with the feed port of the desulfurization reaction kettle through a conveyer belt, and the discharge port not meeting the requirement of desulfurization particle size is connected with the crushing device or the ball milling device through a conveyer 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 conveyer belt.

7. The system for desulfurizing 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 reaction kettle is used, a stirrer and a heating structure are arranged in the reaction kettle; when the wet-process phosphoric acid storage tank is used, a stirrer is arranged in the wet-process 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 ore sand and a secondary crushing structure capable of crushing to obtain phosphate ore powder, a discharge port of the primary crushing structure is output in two ways through a conveying belt, one way is output to a feed port of the secondary crushing structure, and the other way is output to a feed port of the screening device; other discharge gates of the screening device are connected with a feed inlet of the secondary crushing structure through a conveying belt, a discharge gate of the secondary crushing structure is connected with the ball milling device through the conveying belt, and the primary crushing structure and the secondary crushing structure respectively comprise at least one crusher.

9. The desulfurization system of wet phosphoric acid according to claim 8, wherein the primary pulverization structure is a jaw crusher, and the secondary pulverization structure is a cone crusher.

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)₃PO₄) Can be used as raw material for producing compound fertilizer. In the related art, sulfate ions (SO) in phosphoric acid are generated due to production techniques and the like₄ ^2-) The content is usually high (can reach about 3.50 percent), and phosphorus pentoxide (P)₂O₅) The content of (A) is relatively not too high (can reach about 21.5%). Phosphoric acid with the above characteristics (high sulfate ion content, low phosphorus pentoxide content) can cause a reduction in the quality (e.g., total content of active ingredients) of the compound fertilizer. In order to ensure the quality of the phosphate fertilizer, the production process of the phosphoric acid needs to be adjusted; or, the phosphoric acid with higher sulfate ion content is desulfurized and concentrated.

Disclosure of Invention

The embodiment of the invention provides a desulfurization method and a desulfurization system for wet-process phosphoric acid, which comprehensively consider various factors to find an 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 during desulfurization, reduce the transportation and processing difficulty, and avoid great 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 phosphate ore sand with the size of 1-20mm into wet-process phosphoric acid obtained by reacting sulfuric acid, phosphate ore slurry and reverse acid, stirring and reacting for 5 hours-90 days at the temperature of 10-95 ℃, standing and settling, wherein the supernatant is desulfurized phosphoric acid, the lower layer slurry is washed by water and then sent to be ball-milled to be used as a raw material of the phosphate ore slurry, and washing liquid is merged into the return acid, and the using amount of the phosphate ore sand is 4-100 times of the molar weight of sulfuric acid in the wet-process phosphoric acid.

Preferably, the size of the phosphorus ore in the embodiment of the invention is 3-6 mm.

Preferably, the temperature of the stirring reaction in the embodiment of the present invention is 80 to 90 ℃, and the time of the stirring reaction is 16 to 20 hours.

Preferably, the dosage of the phosphate ore in the embodiment of the invention is 4 to 10 times of the molar weight of the sulfuric acid in the wet-process phosphoric acid.

Specifically, the method provided in the embodiment of the present invention specifically includes: adding 3-10mm phosphate ore sand into wet-process phosphoric acid obtained by reacting sulfuric acid, phosphate ore slurry and returned acid, stirring and reacting for 16-20 hours at 80-90 ℃, standing and settling, wherein the supernatant is desulfurized phosphoric acid, the lower layer slurry is washed by water and then sent to be ball-milled to be used as a raw material of the phosphate ore slurry, and the washing liquid is merged into the returned acid, wherein the use amount of the phosphate ore sand is 30-50 times of the molar weight of the sulfuric acid in the wet-process phosphoric acid.

Specifically, in another implementation manner of this patent, the method provided in the embodiment of the present invention specifically includes: adding phosphate rock sand and wet-process phosphoric acid into a wet-process phosphoric acid storage tank, storing at room temperature, intermittently stirring, taking out supernatant 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 multiple times, after 1-3 months, taking lower-layer slurry, washing with water, and then sending the lower-layer slurry to ball milling to serve as a raw material of phosphate pulp, wherein washing liquor is merged into returned acid; the size of the phosphorite sand is 10-20mm, and the dosage of the phosphorite sand is 200 times of 100 times of the molar weight of sulfuric acid in the wet-process phosphoric acid.

Further, in the invention, after the phosphorite is crushed for the first time, part or all of ore sand is sieved, the phosphorite sand with the size of 1-20mm is sent to wet-process phosphoric acid for desulfurization, the residual ore sand after the primary crushing and other ore sand obtained by sieving are crushed for the second time to obtain phosphorite powder, and the phosphorite powder is ball-milled with process water to obtain phosphorite pulp.

Further, in another embodiment of the invention, after the phosphorite is crushed, part or all of the ore sand is sieved, the phosphorite sand with the size of 1-20mm is sent to wet-process phosphoric acid for desulfurization, and the phosphorite sand with the size of less than 1mm and the rest crushed ore sand are ball-milled with process water to obtain phosphorite pulp.

On the other hand, the embodiment of the invention also provides a wet-process phosphoric acid desulfurization system, 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 settling tank, wherein the crushing device, the ball milling device, the thickening device, the synthesis reaction kettle, the filtering device, the desulfurization reaction kettle and the settling tank 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 port of the screening device is connected with the discharge port of the crushing device through a conveyer belt, the discharge port meeting the requirement of desulfurization particle size is connected with the feed port of the desulfurization reaction kettle through a conveyer belt, and the discharge port not meeting the requirement of desulfurization particle size is connected with the crushing device or the ball milling device through a conveyer 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 conveyer 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 reaction kettle is used, a stirrer and a heating structure are arranged in the reaction kettle; when the wet-process phosphoric acid storage tank is used, a stirrer is arranged in the wet-process 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 rock 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 ways through a conveying belt, one way is output to a feed port of the secondary crushing structure, and the other way is output to a feed port of the screening device; other discharge gates of the screening device are connected with a feed inlet of the secondary crushing structure through a conveying belt, a discharge gate of the secondary crushing structure is connected with the ball milling device through the conveying belt, and the primary crushing structure and the secondary crushing structure respectively comprise at least one 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 following beneficial effects: the embodiment of the invention provides a desulfurization method and a desulfurization system for wet-process phosphoric acid, which have the following advantages:

1. can remove SO in wet-process phosphoric acid₃The concentration is reduced to 0.3-0.6%, which is consistent with the effect of 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 obviously increased.

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 technical improvement investment is low.

6. Although the desulfurization time is slightly longer than that of the ore powder and the ore pulp, the total treatment time of the phosphoric acid is 10 to 30 percent shorter 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 shredder according to an embodiment of the present invention;

FIG. 3 is a schematic block diagram of another wet-process phosphoric acid desulfurization system provided by an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.