阅读说明：本技术 一种用卤水做原料生产硝酸钾的工艺 (Process for producing potassium nitrate by using brine as raw material ) 是由 王涛 蒲国心 于 2020-05-15 设计创作，主要内容包括：本发明涉及一种用卤水做原料生产硝酸钾的工艺,属于卤水资源化利用领域,具体步骤包括硝酸钙与卤水中的硫酸镁反应生成硫酸钙和硝酸镁,硫酸钙过滤洗涤后用于生产α-石膏,滤液浓缩结晶析出氯化钠,过滤氯化钠后的滤液,加入氯化钾充分搅拌,再冷却降温结晶析出硝酸钾,过滤硝酸钾后的滤液,再经浓缩降温结晶析出六水氯化镁。不但将卤水中的钾转化为高附加值的硝酸钾,而且将卤水中含有的各种物质,进行了综合利用,节省了资源,产生较高的经济效益。(The invention relates to a process for producing potassium nitrate by using brine as a raw material, belonging to the field of brine resource utilization. The potassium in the brine is converted into potassium nitrate with high added value, and various substances contained in the brine are comprehensively utilized, so that resources are saved, and higher economic benefit is generated.)

1. A process for producing potassium nitrate by using brine as a raw material is characterized by comprising the following steps:

adding calcium nitrate into the brine, and reacting to generate calcium sulfate and magnesium nitrate;

filtering and washing calcium sulfate to produce alpha-gypsum, concentrating and crystallizing the filtrate to separate out sodium chloride, adding potassium chloride into the filtrate after the sodium chloride is filtered, uniformly mixing, cooling and crystallizing to separate out potassium nitrate, concentrating and cooling the filtrate after the potassium nitrate is filtered to separate out magnesium chloride hexahydrate.

2. The process for producing potassium nitrate from brine as claimed in claim 1, wherein the water used for washing the calcium sulfate is transferred to the brine of the next batch.

3. The process for preparing potassium nitrate from brine as claimed in claim 1, wherein the amount of calcium nitrate added to the brine is equal to the amount of magnesium sulfate added to the brine.

4. The process for producing potassium nitrate by using brine as a raw material according to claim 1, wherein the temperature of concentrated crystallization is 110-125 ℃.

5. The process for producing potassium nitrate by using brine as a raw material according to claim 1, wherein the temperature is reduced to-20 ℃ to-5 ℃.

6. The process for preparing potassium nitrate from brine as claimed in claim 1, wherein the amount of potassium chloride added is 2 times the molar amount of magnesium sulfate in the brine, less than the amount of potassium chloride contained in the brine.

7. The process for producing potassium nitrate from brine as claimed in claim 1, wherein the water used to wash the potassium nitrate is used to crystallize sodium chloride by multi-effect evaporation the next time.

8. The process for producing potassium nitrate by using brine as a raw material according to claim 1, wherein the concentration and temperature reduction comprises the following specific steps: concentrating to 135-155 deg.C, and cooling to 70-85 deg.C.

9. Potassium nitrate produced by the process of any one of claims 1 to 8.

10. Use of potassium nitrate as claimed in claim 9 in the manufacture of black powder, matches, glass articles, photonic glass, ceramic articles, pharmaceuticals.

Technical Field

The invention belongs to the field of brine resource utilization, and particularly relates to a preparation process for producing potassium nitrate by using brine as a raw material.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Potassium nitrate is an important inorganic chemical raw material, and is mainly used for manufacturing black powder, matches, glass products, photon glass, ceramic products and medicines.

Potassium nitrate is an important binary potassium fertilizer in agriculture, contains 13.5-13.9% of nitro nitrogen and 44.6-46% of potassium oxide, and during the growth period of tobacco and tea, potassium nitrate is used to replace potassium sulfate, so that the sulfur content of tobacco and tea can be reduced, and the taste of tobacco and tea can be improved. Potassium nitrate has high solubility in water and is not easy to volatilize, so that the potassium nitrate is the best ingredient for liquid fertilizers. After fertilization, the potassium nitrate can be completely absorbed by plants, and chemical residues can not be brought to the ecological environment.

With the development of society and the improvement of the living standard of people's material culture, the requirement for material is continuously expanded, and land resources are less and less. The ocean covers two thirds of the earth, contains rich elements required by people for life, taking potassium as an example, and according to statistics, the potassium dissolved in seawater is about 600 trillion tons, so that the ocean is an inexhaustible resource, and is a non-negligible resource for countries lacking soluble potassium mineral salts. China is a large population country, a large agricultural country and a potassium-deficient country, so that potassium extraction from seawater is one of the ways to solve potassium deficiency. The total amount of potassium in seawater is huge, but the content is low, and the average content is only 0.33%. Although the potassium content of brine obtained after sun-drying salt is improved, other components are correspondingly improved to form a complex system, and the separation of all substances is very difficult, so that the inventor finds that: for a long time, due to the technical difficulty of brine utilization, economic benefits are not produced, brine obtained after sodium chloride is extracted from seawater in various salt farms is discharged into the sea, and serious damage is caused to offshore marine ecology in the years.

Disclosure of Invention

In order to overcome the problems, the invention provides a process for preparing potassium nitrate by taking brine as a raw material. The potassium in the brine is converted into potassium nitrate with high added value, and various substances contained in the brine are comprehensively utilized, so that resources are saved, and higher economic benefit is generated.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

the invention provides a process for producing potassium nitrate by using brine as a raw material, which comprises the following steps:

adding calcium nitrate into the brine, and reacting to generate calcium sulfate and magnesium nitrate;

filtering and washing calcium sulfate to produce alpha-gypsum, concentrating and crystallizing the filtrate to separate out sodium chloride, adding potassium chloride into the filtrate after the sodium chloride is filtered, uniformly mixing, cooling and crystallizing to separate out potassium nitrate, concentrating and cooling the filtrate after the potassium nitrate is filtered to separate out magnesium chloride hexahydrate.

The inventor has made a major breakthrough in the technology of brine resource utilization through years of research and customs, and by adding calcium nitrate into brine resources, the dissolution balance of substances in the brine is broken, so that not only is low-cost potassium nitrate obtained, but also useful substances such as sodium chloride, magnesium chloride hexahydrate and the like are separated from the brine, and the brine which originally has a destructive effect on marine ecology is utilized.

In a second aspect of the present invention there is provided potassium nitrate prepared by any one of the above processes.

The method not only converts potassium in the brine into potassium nitrate with high added value, but also comprehensively utilizes various substances contained in the brine, saves resources and generates higher economic benefit.

In a third aspect of the invention, the potassium nitrate is applied to the manufacture of black powder, matches, glass products, photon glass, ceramic products and medicines.

The method effectively solves the problem of high added value conversion of potassium in the brine, saves resources, has good economic benefit, and realizes industrial production, thereby meeting the requirements of raw materials such as black powder, matches, glass products, photon glass, ceramic products, medicines and the like.

The invention has the beneficial effects that:

(1) the method not only converts potassium in the brine into potassium nitrate with high added value, but also comprehensively utilizes various substances contained in the brine, saves resources and generates higher economic benefit.

(2) The method is simple, low in cost, strong in practicability and easy to popularize.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The invention provides a process for preparing potassium nitrate by taking brine as a raw material, which comprises the following steps: the sulfuric acid in the brine is precipitated with calcium nitrate and magnesium nitrate is formed.

Ca(NO₃)₂+MgSO₄→CaSO₄↓+Mg(NO₃)₂

Magnesium nitrate and potassium chloride are subjected to double decomposition reaction to generate potassium nitrate

Mg(NO₃)₂+2KCl→MgCl₂+2KNO₃

Filtering and separating the filtrate of calcium sulfate, concentrating to the liquid temperature of 110-125 ℃, crystallizing sodium chloride (more than 98 percent of sodium chloride in brine is crystallized out), and washing the crystallized sodium chloride with water to obtain the sodium chloride with the content of more than 98 percent.

And (3) supplementing potassium chloride into the filtrate after the sodium chloride is crystallized, wherein the quantity of the supplemented potassium chloride is 2 times of the molar quantity of the calcium nitrate, and the quantity of the potassium chloride in the brine is reduced. After fully stirring, carrying out double decomposition reaction on potassium chloride and generated magnesium nitrate to generate potassium nitrate:

2KCl+Mg(NO₃)₂→2KNO₃+MgCl₂

cooling the reaction liquid to 0-20 deg.c to crystallize and separate out potassium nitrate, centrifuging, water washing and stoving to obtain potassium nitrate with potassium nitrate content over 98%.

Concentrating the filtrate after centrifuging potassium nitrate to liquid temperature of 135-155 ℃, transferring the concentrated liquid to a cooling crystallization kettle for vacuum cooling crystallization, keeping the temperature until the liquid temperature is 65-85 ℃, centrifugally filtering magnesium chloride hexahydrate after crystallization is complete, washing the magnesium chloride hexahydrate after centrifugation with water, wherein the content of magnesium chloride can reach 45-46%, and mechanically applying the filtrate of the magnesium chloride hexahydrate to concentration and one-step crystallization to produce potassium nitrate.

In order to improve the utilization rate of potassium chloride in the brine, after magnesium hydroxide and magnesium oxide are extracted from the brine, the potassium chloride content can be improved to be more than 60kg per cubic volume of the brine, the potassium chloride supplementing amount is reduced, the utilization rate of potassium chloride in the brine is improved, and the cost is reduced.

A process for producing potassium nitrate by using brine as a raw material comprises the following production steps:

adding calcium nitrate into brine, filtering the generated calcium sulfate, and using the calcium sulfate water washing sleeve into the brine of the next batch.

Filtering the filtrate of the calcium sulfate, evaporating and concentrating the filtrate in multiple effects to the liquid temperature of 110-125 ℃, crystallizing out sodium chloride, and recycling the sodium chloride washing water to the next batch of filtrate for concentration.

Filtering the filtrate, adding potassium chloride while the filtrate is hot, fully stirring, cooling to-20 deg.C to-5 deg.C, and crystallizing to obtain potassium nitrate. The potassium nitrate water washing sleeve is used for next multi-effect evaporation crystallization of sodium chloride.

Concentrating the filtrate after filtering potassium nitrate to liquid temperature of 135-155 ℃, cooling the concentrated solution to 70-85 ℃, crystallizing to separate magnesium chloride hexahydrate, and sleeving the filtrate on next crystallization to produce potassium nitrate.

In some embodiments, calcium nitrate is added to the brine in an amount equimolar to the amount of magnesium sulfate in the brine to precipitate the sulfuric acid from the brine with the calcium nitrate and form magnesium nitrate.

In some embodiments, the calcium sulfate is filtered and the crystalline sodium chloride is concentrated to a concentrate temperature of 110 ℃ to 125 ℃ to increase the crystallization efficiency.

In some embodiments, potassium chloride is added in an amount that is 2 times the moles of magnesium sulfate in the brine minus the amount of potassium chloride contained in the brine, such that potassium chloride undergoes a metathesis reaction with the magnesium nitrate produced to produce potassium nitrate.

In some embodiments, the potassium nitrate crystallization temperature is from-20 ℃ to-5 ℃ to effectively separate the potassium nitrate.

In some embodiments, the mother liquor after potassium nitrate production is concentrated to the liquid temperature of 135-155 ℃, and then cooled to 65-85 ℃ to crystallize and produce magnesium chloride hexahydrate.

The present invention is described in further detail below with reference to specific examples, which are intended to be illustrative of the invention and not limiting.