阅读说明：本技术 硫酸钠型卤水或盐硝母液多联产盐硝钾锂的方法 (Method for poly-generation of potassium lithium nitrate by sodium sulfate type brine or mother liquor of potassium nitrate ) 是由 宋茜茜 刘正友 张文广 马朝辉 郭云云 曹军 于 2018-07-25 设计创作，主要内容包括：本发明涉及一种硫酸钠型卤水或盐硝母液多联产盐硝钾锂的方法,从含有锂、钾资源的硫酸钠型井矿盐卤水,或该类型卤水提取氯化钠、硫酸钠后产生的盐硝母液中提取盐、硝、钾、锂等有用资源的综合利用方法。该方法通过两碱净化、膜过滤、纳滤脱硝、热法制硝、蒸发析盐、蒸发析钾、沉淀法提锂等步骤生产氯化钠、硫酸钠、氯化钾、碳酸锂等产品。本技术方法实现了含锂、钾的硫酸钠型井矿盐卤水或盐硝母液的资源高效利用,实现了盐硝钾锂联产,提高了资源利用率,整个生产过程中无废液排出。(The invention relates to a method for poly-generation of potassium lithium nitrate from sodium sulfate type brine or a sodium nitrate mother liquor, which is a comprehensive utilization method for extracting useful resources such as salt, nitrate, potassium, lithium and the like from sodium sulfate type well and mine salt brine containing lithium and potassium resources or the salt nitrate mother liquor generated after sodium chloride and sodium sulfate are extracted from the sodium sulfate type well and mine salt brine. The method comprises the steps of two-alkali purification, membrane filtration, nanofiltration denitration, hot-method nitrate preparation, evaporation salt precipitation, evaporation potassium precipitation, precipitation lithium extraction and the like to produce products such as sodium chloride, sodium sulfate, potassium chloride, lithium carbonate and the like. The technical method realizes the high-efficiency utilization of the resources of the sodium sulfate type well mineral salt brine containing lithium and potassium or the salt nitrate mother liquor, realizes the co-production of the salt nitrate, the potassium and the lithium, improves the utilization rate of the resources and does not discharge waste liquor in the whole production process.)

1. A method for poly-generation of lithium potassium nitrate from low-nitrate brine comprises the following steps:

(1) the low-nitrate brine enters a membrane filtration system for further purification after calcium and magnesium are removed;

(2) allowing the brine obtained in the step (1) to pass through a nanofiltration membrane device to obtain high-nitrate brine and low-nitrate brine respectively, wherein the content of sodium sulfate in the low-nitrate brine is less than or equal to 5g/L, and the content of sodium sulfate in the high-nitrate brine is 50-100 g/L;

(3) allowing the high-nitrate brine in the step (2) to enter a sodium sulfate evaporation tank, evaporating and concentrating at 88-108 ℃, performing solid-liquid separation to obtain a nitrate precipitation mother liquor and precipitated sodium sulfate crystals, and dehydrating and drying the precipitated sodium sulfate crystals to obtain anhydrous sodium sulfate products;

(4) discharging the low-nitrate brine obtained in the step (2) and the nitrate precipitation mother liquor obtained in the step (3) into a sodium chloride evaporation tank, carrying out evaporation concentration at 48-88 ℃, carrying out solid-liquid separation, dehydrating precipitated sodium chloride crystals to obtain product salt, and discharging the salt precipitation mother liquor into a potassium chloride evaporation tank;

(5) evaporating and concentrating the salt precipitation mother liquor obtained in the step (4) at 68-88 ℃, carrying out solid-liquid separation, dehydrating precipitated potassium chloride crystals to obtain product salt, and discharging the potassium precipitation mother liquor into a reaction kettle;

(6) heating the potassium separation mother liquor obtained in the step (5) in a reaction kettle to a certain temperature, slowly dropwise adding a sodium carbonate solution with excessive lithium theoretical equivalent into the potassium separation mother liquor, cooling, performing solid-liquid separation, obtaining a lithium carbonate product as filter residue, optionally returning the filtrate to a sodium chloride evaporation tank in the step (4) for evaporation and concentration,

the low-nitrate brine comprises: the NaCl content is 260-320g/L, preferably 280-310g/L, more preferably 290-300 g/L; na (Na)₂SO₄The content is 5-50g/L, preferably 6-30g/L, more preferably 15-22 g/L; the potassium ion content in the low-nitrate brine is 0.1-50g/L, preferably 3-30g/L, and the lithium ion content is more than 10mg/L, for example 10-1500mg/L, preferably 150 mg/L and 1500 mg/L.

2. A method for poly-generation of potassium lithium nitrate by high-nitrate brine or salt nitrate mother liquor comprises the following steps:

(1) removing calcium and magnesium from high-nitrate brine or salt-nitrate mother liquor, and then purifying in a membrane filtration system;

(2) feeding the purified brine or the saltpeter mother liquor into a sodium sulfate evaporation tank, carrying out evaporation concentration at 88-108 ℃, carrying out solid-liquid separation to obtain separated sodium sulfate crystals and saltpeter mother liquor, and dehydrating and drying the separated sodium sulfate crystals to obtain a product anhydrous sodium sulfate;

(3) discharging the nitrate precipitation mother liquor obtained in the step (2) into a sodium chloride evaporation tank, carrying out evaporation concentration at 48-88 ℃, carrying out solid-liquid separation, dehydrating precipitated sodium chloride crystals to obtain sodium chloride product salt, and discharging the salt precipitation mother liquor into a potassium chloride evaporation tank;

(4) evaporating and concentrating the salt precipitation mother liquor obtained in the step (3) at 68-88 ℃, carrying out solid-liquid separation, dehydrating the precipitated potassium chloride crystals to obtain potassium chloride product salt, and discharging the potassium precipitation mother liquor into a reaction kettle;

(5) heating the potassium separation mother liquor obtained in the step (4) in a reaction kettle to a certain temperature, slowly dropwise adding a sodium carbonate solution with excessive lithium theoretical equivalent into the potassium separation mother liquor, cooling, performing solid-liquid separation, obtaining a lithium carbonate product as filter residue, returning the filtrate to the sodium chloride evaporation tank in the step (3) for evaporation and concentration,

wherein, the high-nitre brine comprises: the NaCl content is 10-350g/L, preferably 50-200g/L, more preferably 100-150 g/L; na (Na)₂SO₄The content is 50-360g/L, preferably 100-300g/L, more preferably 150-260g/L,

the content of potassium ions in the high-nitrate brine is 0.1-50g/L, preferably 3-30g/L, and the content of lithium ions is 10-1500mg/L, preferably 150-1500 mg/L;

wherein, the saltpeter mother liquor comprises: the NaCl content is 200-320g/L, preferably 240-300 g/L; na (Na)₂SO₄The content is 30-180g/L, preferably 50-150g/L, the content of potassium ions is 1-100g/L, preferably 10-50g/L, and the content of lithium ions is more than 100mg/L, such as 100-2000mg/L, preferably 200-2000 mg/L.

3. The method as claimed in claim 2, wherein the saltpeter mother liquor is a solution obtained by extracting sodium chloride and sodium sulfate with sodium sulfate type brine.

4. The method according to claim 1 or 2, wherein the membrane in the membrane filtration system in step (1) is one of ceramic membrane, Gole membrane and organic membrane, and the pore size of the membrane is 80-20nm, preferably 50-30 nm.

5. The method of claim 1 or 2, wherein the calcium and magnesium ions in the original solution are removed by the two-alkali method in the step (1), and the total amount of the calcium and magnesium ions in the brine after membrane filtration is less than or equal to 1 mg/L.

6. The process according to claim 1 or 2, wherein the potassium-evolving mother liquor is heated in the reactor at a temperature of 75-95 ℃, preferably 80-90 ℃, further for example 85 ℃.

7. The process as claimed in claim 1 or 2, wherein the concentration of the sodium carbonate solution added dropwise to the potassium-evolving mother liquor is from 1 to 4mol/L, and a sodium carbonate solution having an excess of the theoretical equivalent of lithium (for example, 101-.

8. The process of claim 1 or 2, wherein the lithium carbonate product obtained is of purity Li₂CO₃≧99wt％。

9. The method of claim 5, wherein the two-base process comprises: the raw materials enter a reaction barrel and are added at normal temperature100% theoretical equivalents of NaOH and Na₂CO₃Removing calcium and magnesium impurities from the solution, aging for 1-2 hours, discharging calcium mud and magnesium mud from the bottom, and allowing the supernatant to enter a membrane filtration device.

Technical Field

The invention relates to a method for poly-generation of potassium lithium nitrate by using sodium sulfate type brine or a mother solution of the potassium nitrate, belonging to the technical field of comprehensive utilization of resources.

Background

The well and mineral salt brine is underground natural brine drawn by well drilling or brine formed by water-soluble exploitation of underground rock salt, and mainly comprises a sodium sulfate type and a calcium sulfate type, wherein the sodium sulfate type accounts for more than 2/3. The sodium sulfate type well mineral salt brine contains sodium chloride, sodium sulfate and other main components, and also contains lithium, potassium and other trace elements. At present, most of sodium sulfate type brine in China is extracted and utilized by nitrate or salt-nitrate co-production. The process can generate a large amount of saltpeter mother liquor, the saltpeter mother liquor is injected into a well and is infinitely circulated in the system, so that the product quality is lowered, or the mother liquor is discharged, so that the environment is polluted. At present, the resources such as sodium chloride, sodium sulfate, lithium, potassium and the like in the mother liquor can not be effectively utilized by any mother liquor treatment method, so that a large amount of resources are wasted.

As an important strategic resource, lithium has a good application prospect, and the lithium consumption in China is increasing year by year. The domestic lithium salt production mainly adopts hard rock type and salt lake brine type lithium ore resources, and the lithium resources in well mine brine are not developed and utilized due to low lithium content. How to develop and utilize lithium resources to the maximum extent and promote the sustainable development of the lithium industry in China becomes a problem to be solved urgently.

Disclosure of Invention

The invention aims to provide a high-efficiency utilization method of poly-generation of lithium potassium nitrate, aiming at the defects of insufficient development and utilization of resources such as lithium, potassium and the like in well and mineral brine and the waste of lithium potassium nitrate in a salt and nitrate mother liquor at present.

According to a first embodiment of the present invention, there is provided a process for the poly-generation of lithium potassium nitrate from a low-nitrate brine, the process comprising:

(1) after calcium and magnesium are removed from the low-nitrate brine, the low-nitrate brine enters a membrane filtration system for further purification, preferably, the total amount of calcium and magnesium ions in the purified brine is less than or equal to 1mg/l, so that the purified brine is obtained;

(2) passing the brine obtained in the step (1) through a nanofiltration membrane device to respectively obtain high-nitrate brine and low-nitrate brine, wherein the content of sodium sulfate in the low-nitrate brine is less than or equal to 5g/L, such as 1-5g/L, and the content of sodium sulfate in the high-nitrate brine is 50-100g/L, and further 60-90 g/L;

(3) allowing the high-nitrate brine in the step (2) to enter a sodium sulfate evaporation tank, evaporating and concentrating at 88-108 ℃, preferably 95-100 ℃, performing solid-liquid separation to obtain a nitrate precipitation mother liquor and precipitated sodium sulfate crystals, and dehydrating and drying the precipitated sodium sulfate crystals (for example, at 120-150 ℃) to obtain anhydrous sodium sulfate;

(4) discharging the low-nitrate brine obtained in the step (2) and the nitrate precipitation mother liquor obtained in the step (3) into a sodium chloride evaporation tank, carrying out evaporation concentration at 48-88 ℃, preferably 60-80 ℃, carrying out solid-liquid separation, dehydrating precipitated sodium chloride crystals to obtain product salt, and discharging the salt precipitation mother liquor into a potassium chloride evaporation tank;

(5) evaporating and concentrating the salt precipitation mother liquor in the step (4) at 68-88 ℃, preferably 72-80 ℃, carrying out solid-liquid separation, dehydrating the precipitated potassium chloride crystals to obtain product salt, and discharging the potassium precipitation mother liquor into a reaction kettle;

(6) in the step (5), heating the potassium separation mother liquor in a reaction kettle to a certain temperature (for example, above 40 ℃, preferably 75-95 ℃, preferably 80-90 ℃, further for example, about 85 ℃), slowly dropwise adding a sodium carbonate solution with excess lithium theoretical equivalent (for example, 101-.

Further, the membrane in the membrane filtration system in the step (1) is one of a ceramic membrane, a Gole membrane and an organic membrane, and the pore diameter of the membrane is 80-20nm, preferably 50-30 nm.

The nanofiltration membrane in the step (2) can be selected from NF series nanofiltration membranes of Filmtec company, NTR-7400 series nanofiltration membranes of Nidong electrician, UTC series nanofiltration membranes of Dongli company, and the like.

According to a second embodiment of the present invention, there is provided a method for poly-generation of lithium potassium nitrate from high-nitrate brine or a mother liquor of the sodium nitrate, the method comprising:

(1) after calcium and magnesium are removed from the high-nitrate brine or the salt-nitrate mother liquor, the high-nitrate brine or the salt-nitrate mother liquor enters a membrane filtration system for further purification, preferably, the total amount of calcium and magnesium ions in the purified brine or the salt-nitrate mother liquor is less than or equal to 1 mg/l;

(2) feeding the purified brine or the saltpeter mother liquor into a sodium sulfate evaporation tank, evaporating and concentrating at 88-108 ℃, preferably 95-100 ℃, performing solid-liquid separation to obtain separated sodium sulfate crystals and saltpeter mother liquor, and performing dehydration drying (such as centrifuge dehydration and drying bed drying, for example at 120-150 ℃) on the separated sodium sulfate crystals to obtain a product anhydrous sodium sulfate;

(3) discharging the nitrate precipitation mother liquor obtained in the step (2) into a sodium chloride evaporation tank, evaporating and concentrating at 48-88 ℃, preferably 60-80 ℃, performing solid-liquid separation, dehydrating precipitated sodium chloride crystals to obtain sodium chloride product salt, and discharging the salt precipitation mother liquor into a potassium chloride evaporation tank;

(4) evaporating and concentrating the salt precipitation mother liquor obtained in the step (3) at 68-88 ℃, preferably 72-80 ℃, carrying out solid-liquid separation, dehydrating precipitated potassium chloride crystals to obtain potassium chloride product salt, and discharging the potassium precipitation mother liquor into a reaction kettle;

(5) heating the potassium-separating mother liquor obtained in the step (4) in a reaction kettle to a certain temperature (for example, above 40 ℃, preferably 75-95 ℃, preferably 80-90 ℃, further for example, about 85 ℃), slowly dropwise adding a sodium carbonate solution (for example, 1-4mol/L sodium carbonate aqueous solution) with excess lithium theoretical equivalent (for example, 101-.

Further, the low-nitrate brine and the high-nitrate brine are sodium sulfate type brine, and the low-nitrate brine comprises the following components: the NaCl content is 260-320g/L, preferably 280-310g/L, more preferably 290-300 g/L; na (Na)₂SO₄The content is 5-50g/L, preferably6-30g/L, more preferably 15-22 g/L;

the high-nitrate brine comprises the following components: the NaCl content is 10-350g/L, preferably 50-200g/L, more preferably 100-150 g/L; na (Na)₂SO₄The content is 50-360g/L, preferably 100-300g/L, more preferably 150-260g/L,

furthermore, the potassium ion content in the low-nitrate brine or the high-nitrate brine is 0.1-50g/L, preferably 3-3mg/L, and the lithium ion content is more than 10mg/L, for example 10-1500mg/L, preferably 150 mg/L.

Further, the saltpeter mother liquor refers to a solution generated after extracting sodium chloride and sodium sulfate from sodium sulfate type brine, and the saltpeter mother liquor comprises the following components: the NaCl content is 200-320g/L, preferably 240-300 g/L; na (Na)₂SO₄The content is 30-180g/L, preferably 50-150g/L, the content of potassium ions is 1-100g/L, preferably 10-50g/L, and the content of lithium ions is more than 100mg/L, such as 100-2000mg/L, preferably 200-2000 mg/L.

Further, the membrane in the membrane filtration system in the step (1) is one of a ceramic membrane, a Gole membrane and an organic membrane, and the pore diameter of the membrane is 80-20nm, preferably 50-30 nm.

Further, the step (1) removes calcium and magnesium ions in the original solution by using a two-alkali method, and comprises the following specific steps: the raw materials are fed into a reaction barrel, and 100% of theoretical equivalent of 30% NaOH and Na, for example, are added at normal temperature₂CO₃Removing calcium and magnesium impurities from the solution, aging for 1-2 hours, discharging calcium mud and magnesium mud from the bottom, and allowing the supernatant to enter a membrane filtration device. The total amount of calcium and magnesium ions in the brine after membrane filtration is less than or equal to 1 mg/L.

Further, the volume ratio of the low nitrate saline to the high nitrate saline in the step (2) is generally 2-3:1, for example, about 2.5: 1.

Further, the heating temperature of the potassium precipitation mother liquor in the reaction kettle is 75-95 ℃, preferably 80-90 ℃, and further for example 85 ℃.

Further, the concentration of the sodium carbonate solution in the potassium separating mother liquor is 1-4mol/L, for example about 3 mol/L.

Further, the purity of the obtained lithium carbonate product is Li₂CO₃≧99wt％。

The invention has the advantages that:

1. the method for poly-generation of sodium sulfate type well and mineral salt brine containing lithium and potassium nitrate lithium can develop and utilize high-added-value lithium and potassium resources in well and mineral salt brine, and improve the resource utilization rate.

2. The method for poly-generation of the salt, the potassium and the lithium in the common lithium and potassium-containing salt and nitrate mother liquor is provided, the sodium chloride, the sodium sulfate, the potassium chloride, the lithium carbonate and other products are produced through the steps of two-alkali purification, membrane filtration, nanofiltration denitration, hot-method nitrate preparation, evaporation salt precipitation, evaporation potassium precipitation, precipitation lithium extraction and the like, waste is changed into valuable, and the problem that the discharge of the salt and nitrate mother liquor pollutes the environment or the product quality is reduced due to infinite circulation in a system is solved.

3. The method for poly-generation of potassium lithium nitrate and salt of brine or mother liquor containing low-concentration lithium and potassium is provided, the combination of potassium lithium development and salt-nitrate co-generation is realized, the method is a resource integration development method, and useful components in the brine or the mother liquor are developed and utilized to the maximum extent. Can be combined with the prior salt and nitrate co-production, saves investment and enlarges benefit.

Drawings

FIG. 1 is a schematic flow diagram of a method for poly-generation of potassium lithium nitrate from low-nitrate brine.

FIG. 2 is a schematic flow chart of a method for poly-generation of potassium lithium nitrate from high-nitrate brine or a salt-nitrate mother liquor.

Detailed Description

For a further understanding of the invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings and examples, but not to be limiting of the invention, and it is to be understood that the description is intended to further illustrate the features and advantages of the invention, rather than to limit the claims. Any equivalent replacement in the field made in accordance with the present disclosure is within the scope of the present invention.