Process for refining primary saline water and preparing by-product slow-release compound fertilizer
阅读说明：本技术 一次盐水精制副产缓释型复合肥料的工艺 (Process for refining primary saline water and preparing by-product slow-release compound fertilizer ) 是由 陈浩 张强 冯冬娅 于 2020-11-25 设计创作，主要内容包括：本发明公开了一种高效经济的一次盐水精制副产缓释型复合肥料的工艺,包括如下步骤：将粗盐水的pH值调节为10～12,再与H_3PO_4溶液混合至pH为9～11,固液分离；所述粗盐水的溶质为工业氯化钾。本发明方法简单,通过优化一次盐水精制过程,有效地降低了离子膜电解钾碱工艺一次盐水中的钙镁离子含量,并且得到了副产富含钙、镁、钾、硅、氯的缓释复合肥料。(The invention discloses a process for refining primary brine and producing a byproduct slow-release compound fertilizer with high efficiency and economy, which comprises the following steps: adjusting the pH value of the crude brine to 10-12, and then mixing the crude brine with H 3 PO 4 Mixing the solution until the pH value is 9-11, and carrying out solid-liquid separation; the solute of the crude brine is industrial potassium chloride. The method is simple, the content of calcium and magnesium ions in the primary brine in the ionic membrane electrolytic potash process is effectively reduced by optimizing the primary brine refining process, and the by-product sustained-release compound fertilizer rich in calcium, magnesium, potassium, silicon and chlorine is obtained.)
1. The process for refining the primary brine and preparing the byproduct slow-release compound fertilizer is characterized by comprising the following steps of: adjusting the pH value of the crude brine to 10-12, and then mixing the crude brine with H3PO4Mixing the solution until the pH value is 9-11, and carrying out solid-liquid separation;
the solute of the crude brine is industrial potassium chloride.
2. The process according to claim 1, wherein the concentration of the crude brine is 280 to 350g/L, preferably 300 to 330 g/L.
3. The process of claim 1, wherein the pH of the crude brine is adjusted to 10 to 12 by KOH or a KOH solution; further, KOH solution with the mass fraction of 30-48% is adopted to adjust the pH value of the crude brine to 10-12.
4. According to the rightThe process of claim 1, wherein H is3PO4The mass fraction of the solution is 5-20%.
5. The process of claim 1, wherein H is3PO4And after the solutions are mixed, standing the generated solid-liquid mixed system for natural sedimentation for 10-25 s, and then carrying out solid-liquid separation.
6. The process of claim 1 wherein H is3PO4Before the solution is mixed, the temperature of a solution system is 50-90 ℃, and preferably 60-80 ℃;
further, with H3PO4After the solution mixing is completed, the solution system is cooled and settled.
7. The process according to any one of claims 1 to 6, wherein the solid-liquid separation is followed by granulating and drying of the solid matter, and further wherein the particle diameter of the granules obtained after the granulation is 2 to 5 mm.
8. A slow-release compound fertilizer comprising the solid obtained by the method according to any one of claims 1 to 7.
9. The process of claim 8, wherein the compound fertilizer comprises the following components in parts by weight: 15-20 parts of potassium chloride, 10-20 parts of magnesium, 3-10 parts of calcium, 3-8 parts of phosphorus and 15-20 parts of silicon dioxide.
10. A slow-release compound fertilizer characterized by being produced from the solid obtained by the method according to any one of claims 1 to 9.
Technical Field
The invention belongs to the field of chlor-alkali industry, and particularly relates to a process for refining primary brine and producing a byproduct slow-release compound fertilizer.
Background
The potassium hydroxide has a chemical formula of KOH, is white powder or flaky solid, has strong basicity and corrosivity, is very easy to absorb moisture in air to deliquesce, and absorbs carbon dioxide to form potassium carbonate. The potassium hydroxide can be used for producing potassium salt, soap, dye, medicine and desiccant, and preparing progesterone, vanillin, cosmetics, etc., and can be widely applied in the fields of agriculture, daily chemicals, pharmacy, dye, medicine, etc.
In the current industrial production process of potassium hydroxide, the potassium chloride raw material contains a large amount of impurities such as soil, calcium, magnesium and the like, and the brine refining process needs to be carried out twice on the potassium chloride raw material. Wherein, the primary brine refining mainly comprises the steps of precipitating and separating mud and most of calcium and magnesium ions in raw materials, and if the content of the calcium and magnesium ions is too high, the load of a resin tower in the secondary brine refining process is too high, the resin dosage is increased, and the regeneration cost is increased. The traditional two-alkali refining method has no obvious effect on removing calcium and magnesium ions, and the obtained salt mud can only be directly discarded, so that the resource waste is caused, and the treatment cost of solid waste is increased.
In fact, the salt slurry produced in the primary brine refining process contains a large amount of calcium, magnesium, potassium, silicon, chlorine and the like, and is expected to be used as a raw material of an active fertilizer. However, the traditional primary brine refining process does not consider the fertilizer effect of the salt slurry, so that the obtained salt slurry is uneven in distribution of all components, high in calcium and magnesium content, single in fertilizer elements, poor in fertilizer efficiency and release performance and not suitable for being directly used as a fertilizer.
Disclosure of Invention
The invention aims to provide an efficient and economic process for refining primary brine and producing a byproduct of a slow-release compound fertilizer, which can be used for refining the primary brine with low calcium and magnesium content and producing the byproduct of the slow-release compound fertilizer rich in calcium, magnesium, potassium, silicon and chlorine, and can slowly release fertilizer efficiency and be fully absorbed by plants.
In order to more fully and effectively utilize the salt mud in the process of industrially producing potassium hydroxide, the inventor has surprisingly found through a large number of experimental studies that the content of calcium and magnesium impurities in primary brine can be greatly reduced by accurately controlling the technological parameters such as pH, temperature, retention time and the like in the primary brine refining process, and a slow-release compound fertilizer which is rich in calcium, magnesium, potassium, silicon and chlorine and can effectively control the fertilizer efficiency release speed as a byproduct can be obtained, so that the elements such as calcium, magnesium, phosphorus, potassium, chlorine, silicon and the like in the compound fertilizer are gradually released and are fully absorbed by plants.
In order to achieve the above object, the present invention provides a primary brine purificationThe process of producing slow released composite fertilizer as side product includes the following steps: adjusting the pH value of the crude brine to 10-12, and then mixing the crude brine with H3PO4Mixing the solution until the pH value is 9-11, and carrying out solid-liquid separation;
the solute of the crude brine is industrial potassium chloride.
The industrial potassium chloride provided by the invention is industrial potassium chloride with quality grades such as product properties, net content and the like meeting the national standard GB/T7118-.
In the specific embodiment of the invention, the concentration of the crude brine is 280-350 g/L, and preferably 300-330 g/L.
In the specific embodiment of the invention, KOH or KOH solution is adopted to adjust the pH value of the crude brine to 10-12; further, KOH solution with the mass fraction of 30-48% is adopted to adjust the pH value of the crude brine to 10-12.
Said H3PO4The mass fraction of the solution is 5-20%.
In the present embodiment, with H3PO4And after the solutions are mixed, standing the generated solid-liquid mixed system for natural sedimentation for 10-25 s, and then carrying out solid-liquid separation.
In the present embodiment, the compound is represented by formula II3PO4Before the solution is mixed, the temperature of a solution system is 50-90 ℃, and preferably 60-80 ℃;
further, with H3PO4After the solution mixing is completed, the solution system is cooled and settled.
According to the above method, the solid is subjected to solid-liquid separation, and then granulated and dried, and further, the granulated particles have a particle diameter of 2 to 5 mm.
The moisture content of the solid of the invention before granulation is 25-45%, preferably 30-40%.
The invention also provides a slow-release compound fertilizer, which comprises the solid obtained by the method.
The compound fertilizer comprises the following components in parts by weight: 15-20 parts of potassium chloride, 10-20 parts of magnesium, 3-10 parts of calcium, 3-8 parts of phosphorus and 15-20 parts of silicon dioxide.
The invention also provides a slow-release compound fertilizer prepared from the solid obtained by the method.
When the salt mud prepared by the method for refining primary brine is used for preparing the fertilizer, the salt mud prepared by the method can be directly granulated and dried to prepare a fertilizer product; the salt slurry prepared by the invention can be mixed with other components or subjected to processes such as further fermentation to prepare compound fertilizer products and the like, and the salt slurry prepared by the invention is used in the preparation process and belongs to the protection scope of the invention.
Compared with the prior art, the invention has the following beneficial effects:
(1) the calcium and magnesium content of the primary brine obtained by the method is low, and the quality of the primary brine is greatly improved compared with the traditional two-alkali refining process.
(2) The salt mud byproduct of the method is rich in calcium, magnesium, potassium, silicon and chlorine, all components are uniformly distributed, the salt mud can be directly used as a fertilizer, the salt mud fertilizer has good slow release property, inorganic substances after the fertilizer is applied can be slowly dissolved in soil, the release rate of fertilizer efficiency can be effectively controlled, plants can be fully absorbed, and the fertilizer is prevented from being lost too fast.
(3) The method is simple to operate, can realize the efficient utilization of resources in the industrial production process of the potassium hydroxide, and is economic and environment-friendly.
Detailed Description
The technical solutions of the present invention are described clearly and completely below, and it is obvious that the described embodiments are some, not all embodiments of the present invention. Other embodiments, which can be obtained by one skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The dechlorinated brine used in the embodiment of the invention is potassium chloride electrolysis outlet light brine which is dechlorinated and is KCl solution containing about 160 g/L.
Example 1
(1) Heating the dechlorinated salt water solution in the water mixing bucket to 60 ℃, pumping into a salt dissolving pool, mixing and dissolving with solid industrial-grade potassium chloride raw materials, and preparing into 300g/L crude salt water.
(2) The crude brine was passed through a baffle to a crude brine storage tank, to which was added a 30% KOH solution to adjust the pH to 10.
(3) The solution with the PH value of 10 in the step (2) is pumped into 300m3In the clarifying tank, the flow rate is 30m3S, 5% H addition3PO4Adjusting the pH value of the solution to 9 to generate a solid-liquid mixture.
(4) Naturally cooling and settling the solid-liquid mixture in a clarifying barrel, reducing the temperature to 20 ℃, and controlling the retention time of the solid-liquid mixture in the clarifying barrel to be 10 s.
(5) And filtering the supernatant in the clarifying barrel by a Gole filter, and delivering primary brine of the filtrate to secondary brine refining.
(6) And (3) sending the sediment at the middle lower part of the clarifying barrel and the solid intercepted by the Goll filter, namely the salt mud into a plate frame for filter pressing, performing filter pressing until the water content is 30% to obtain a filter cake, and directly granulating the filter cake to obtain solid particles with the particle size of 2-5 mm.
(7) And drying the solid particles to obtain the compound fertilizer rich in calcium, magnesium, phosphorus, potassium and silicon.
Example 2
(1) Heating the dechlorinated salt water solution in the water mixing bucket to 60 ℃, pumping into a salt dissolving pool, mixing and dissolving with solid industrial-grade potassium chloride raw materials, and preparing into 300g/L crude salt water.
(2) The crude brine was passed through a baffle to a crude brine storage tank, to which was added a 30% KOH solution to adjust the pH to 10.
(3) The solution with the PH value of 10 in the step (2) is pumped into 300m3In the clarifying tank, the flow rate is 30m3S, 5% H addition3PO4Adjusting the pH value of the solution to 9 to generate a solid-liquid mixture.
(4) Naturally cooling and settling the solid-liquid mixture in a clarifying barrel, reducing the temperature to 40 ℃, and controlling the retention time of the solid-liquid mixture in the clarifying barrel to be 10 s.
(5) And filtering the supernatant in the clarifying barrel by a Gole filter, and delivering primary brine of the filtrate to secondary brine refining.
(6) And (3) sending the sediment at the middle lower part of the clarifying barrel and the solid intercepted by the Goll filter, namely the salt mud into a plate frame for filter pressing, performing filter pressing until the water content is 30% to obtain a filter cake, and directly granulating the filter cake to obtain solid particles with the particle size of 2-5 mm.
(7) And drying the solid particles to obtain the compound fertilizer rich in calcium, magnesium, phosphorus, potassium and silicon.
Example 3
(1) Heating the dechlorinated salt water solution in the water mixing bucket to 80 ℃, pumping into a salt dissolving pool, mixing and dissolving with solid industrial-grade potassium chloride raw materials, and preparing into crude salt water of 330 g/L.
(2) The crude brine was passed through a baffle to a crude brine storage tank, to which was added a 48% KOH solution to adjust the pH to 10.
(3) The solution with the PH value of 10 in the step (2) is pumped into 300m3In the clarifying tank, the flow rate is 30m3S, 20% H addition3PO4Adjusting the pH value of the solution to 9 to generate a solid-liquid mixture.
(4) Naturally cooling and settling the solid-liquid mixture in a clarifying barrel, reducing the temperature to 40 ℃, and controlling the retention time of the solid-liquid mixture in the clarifying barrel to be 25 s.
(5) And filtering the supernatant in the clarifying barrel by a Gole filter, and delivering primary brine of the filtrate to secondary brine refining.
(6) And (3) sending the sediment at the middle lower part of the clarifying barrel and the solid intercepted by the Goll filter, namely the salt mud into a plate frame for filter pressing, performing filter pressing until the water content is 40% to obtain a filter cake, and directly granulating the filter cake to obtain solid particles with the particle size of 2-5 mm.
(7) And drying the solid particles to obtain the compound fertilizer rich in calcium, magnesium, phosphorus, potassium and silicon.
Comparative example 1 conventional primary brine purification method
(1) Heating the dechlorinated salt water solution in the water mixing bucket to 60 ℃, pumping into a salt dissolving pool, mixing and dissolving with solid industrial-grade potassium chloride raw materials, and preparing into 300g/L crude salt water.
(2) The crude brine was passed through a baffle to a crude brine storage tank, to which was added a 30% KOH solution to adjust the pH to 10.
(3) The solution with the PH value of 10 in the step (2) is pumped into 300m3Adding 1mol/LK into the clarifying tank2CO3The solution was brought to a pH of 10.5 to form a solid-liquid mixture.
(4) And naturally cooling and settling the solid-liquid mixture in a clarifying barrel.
(5) And filtering the supernatant in the clarifying barrel by a Gole filter, and delivering primary brine of the filtrate to secondary brine refining.
(6) And (3) sending the sediment at the middle lower part of the clarifying barrel and the solid intercepted by the Goll filter, namely the salt mud into a plate frame for filter pressing, performing filter pressing until the water content is 30% to obtain a filter cake, and directly granulating the filter cake to obtain solid particles with the particle size of 2-5 mm.
(7) And drying the solid particles to obtain the salt mud particles.
The calcium and magnesium ion content of the primary refined brine obtained in examples 1 to 3 and comparative example 1 was measured, and the measurement results are shown in table 1.
TABLE 1 content of calcium and magnesium ions in the first refined brine
Item
Calcium magnesium ion
Example 1
0.62ppm
Example 2
0.58ppm
Example 3
0.39ppm
Comparative example 1
1.55ppm
As can be seen from table 1, the content of calcium and magnesium ions in the primary refined brine obtained in examples 1 to 3 was 0.39 to 0.62ppm, calcium and magnesium ions in the potassium chloride raw material could be effectively removed, primary refinement of the crude brine could be achieved, and the effect was better than that of the conventional method.
The content of the components of the salty mud obtained in examples 1 to 3 and comparative example 1 was measured, and the measurement results are shown in table 2.
TABLE 2 content of salty mud component
As shown in Table 2, the salty mud obtained in examples 1 to 3 had a KCl content of 16.2 to 20.1%, a Mg content of 12.5 to 16.8%, a Ca content of 3.2 to 4.6%, a P content of 3.4 to 4.1%, and SiO2The content is 15.3% -19.2%, and the content of P in the salt mud obtained in the comparative example 1 is only 0.2%, so that the salt mud obtained by the method is more balanced in fertilizer elements and rich in calcium, magnesium, phosphorus, potassium, chlorine and silicon.
The compound fertilizer obtained in example 2 was subjected to the measurement of the nutrient release rate at 25 ℃ according to the national standard of slow release fertilizers GB/T23348-2009, and the measurement results are shown in Table 3.
TABLE 3 determination of nutrient Release Rate
Time (d)
Total nutrient Release Rate (%)
0-1
8
1-10
32
10-30
38
30-60
13
TABLE 4 determination of nutrient release rate of comparative example 1
Time (d)
Total nutrient Release Rate (%)
0-1
14
1-10
47
10-30
37
30-60
1
From tables 3 and 4, it can be seen that the compound fertilizer obtained in example 2 has a total nutrient release rate of 8% in 0-1 d, 32% in 1-10 d, 38% in 10-30 d, and 13% in 30-60 d, whereas the compound fertilizer obtained in comparative example 1 has a nutrient release rate of 61% in 10d, and is substantially completely released in 30 days, so that the compound fertilizer obtained by the method of the present invention has a slow total nutrient release rate, can prevent the fertilizer from being lost too fast, and can be fully absorbed by plants.
In conclusion, the method effectively reduces the content of calcium and magnesium in the primary brine, can produce a byproduct of the slow-release compound fertilizer rich in calcium, magnesium, potassium, silicon and chlorine, has uniformly distributed element components, contains 15-20% of potassium chloride, 10-20% of magnesium, 3-10% of calcium, 3-8% of phosphorus and 15-20% of silicon dioxide, has balanced fertilizer property and slow nutrient release rate.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
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