阅读说明：本技术 一种制备4n级硝酸镁溶液的方法 (Method for preparing 4N-grade magnesium nitrate solution ) 是由 徐思远 钟学明 徐志宇 于 2019-11-08 设计创作，主要内容包括：本发明一种制备4N级硝酸镁溶液的方法以硝酸镁富集物溶液为料液、P507为萃取剂、TBP为改性剂,由满载分馏萃取分离LiNaMg/MgCaPbAlFe、满载分馏萃取分离LiNa/Mg和分馏萃取分离Mg/CaPbAlFe三个步骤组成,直接制备4N级硝酸镁溶液。目标产品4N级氯化镁溶液的纯度为99.991%～99.997%,镁的收率为96%～98%。本发明具有产品纯度高、镁的收率高、试剂消耗少、分离效率高、工艺流程短、生产成本低等优点。(The invention relates to a method for preparing 4N-grade magnesium nitrate solution, which takes magnesium nitrate enriched solution as feed liquid, P507 as an extracting agent and TBP as a modifying agent and consists of three steps of full-load fractional extraction and separation of LiNaMg/MgCaPbAlFe, full-load fractional extraction and separation of LiNa/Mg and fractional extraction and separation of Mg/CaPbAlFe, so as to directly prepare the 4N-grade magnesium nitrate solution. The purity of the 4N grade magnesium chloride solution of the target product is 99.991-99.997%, and the yield of magnesium is 96-98%. The method has the advantages of high product purity, high magnesium yield, low reagent consumption, high separation efficiency, short process flow, low production cost and the like.)

1. A method for preparing 4N-grade magnesium nitrate solution is characterized by comprising the following steps: the method takes magnesium nitrate enriched solution as feed liquid, P507 as an extracting agent and TBP as a modifier, separates and removes metallic elements of lithium, sodium, calcium, lead, aluminum and iron in the feed liquid, and separates and removes non-metallic elements of chlorine, silicon and sulfur, and directly prepares 4N-grade magnesium nitrate solution; consists of 3 steps, namely full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe, full-load fractionation, extraction and separation LiNa/Mg and fractionation, extraction and separation Mg/CaPbAlFe; the extraction section of full-load fractionation extraction separation LiNaMg/MgCaPbAlFe realizes the separation of LiNaMg/CaPbAlFe, and the washing section realizes the separation of LiNa/MgCaPbAlFe; full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe takes a balanced load P507 organic phase obtained from a full-load fractionation, extraction and separation LiNa/Mg feeding level as an extraction organic phase, and a balanced water phase obtained from a fractionation, extraction and separation Mg/CaPbAlFe feeding level as a detergent; full-load fractionation, extraction and separation LiNa/Mg and fractionation, extraction and separation Mg/CaPbAlFe are directly connected in series; the outlet organic phase of full-load LiNa/Mg fractional extraction separation is used as the extraction organic phase of Mg/CaPbAlFe fractional extraction separation and directly enters the 1 st level of Mg/CaPbAlFe fractional extraction separation; the 1 st level outlet water phase of the Mg/CaPbAlFe separation by fractional extraction is used as a washing agent for full-load LiNa/Mg separation by fractional extraction;

the 3 steps are as follows:

step 1: full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe

Step 1, full-load fractionation, extraction and separation of LiNaMg/MgCaPbAlFe, wherein the extraction section realizes the separation of LiNaMg/CaPbAlFe, and the washing section realizes the separation of LiNa/MgCaPbAlFe; taking a balanced load P507 organic phase obtained from the LiNa/Mg full-load fractional extraction system feeding level in the step 2 as an extraction organic phase, taking a magnesium nitrate enriched solution as a feed liquid, and taking a balanced water phase obtained from the Mg/CaPbAlFe fractional extraction system feeding level in the step 3 as a detergent; the equilibrium loaded P507 organic phase obtained from the LiNa/Mg full-load fractionation extraction system feeding stage of the step 2 enters into the LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the 1 st stage, the magnesium nitrate enriched solution enters into the LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the feeding stage, and the equilibrium aqueous phase obtained from the Mg/CaPbAlFe fractionation extraction system feeding stage of the step 3 enters into the LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the last 1 st stage; obtaining a magnesium nitrate solution containing Li, Na, Cl, Si and S from the water phase at the 1 st level outlet of the LiNaMg/MgCaPbAlFe full-load fractional extraction system, and using the magnesium nitrate solution as feed liquid for full-load fractional extraction separation LiNa/Mg in the step 2; obtaining a P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron from the last 1-level outlet organic phase of the LiNaMg/MgCaPbAlFe full-load fractional extraction system, and using the P507 organic phase as feed liquid for fractional extraction and separation of Mg/CaPbAlFe in the step 3;

step 2: full-load fractionation extraction separation LiNa/Mg

Step 2, full-load fractionation, extraction and separation of LiNa/Mg, and separation and removal of metallic element impurities lithium and sodium and nonmetallic element impurities chlorine, silicon and sulfur in the magnesium nitrate solution; taking a saponified P507 organic phase as an extraction organic phase, taking a magnesium nitrate solution containing Li, Na, Cl, Si and S, which is obtained by fully fractionating a1 st-stage outlet water phase of an extraction system with LiNaMg/MgCaPbAlFe in the step 1, as a feed liquid, and taking a 4N-stage magnesium nitrate solution which is obtained by fractionating the 1 st-stage outlet water phase of the extraction system with Mg/CaPbAlFe in the step 3 as a detergent; the saponified P507 organic phase is an extraction organic phase and enters into a LiNa/Mg full-load fractionation extraction system from the 1 st level, a magnesium nitrate solution containing Li, Na, Cl, Si and S and obtained from a water phase at the 1 st level outlet of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step 1 enters into the LiNa/Mg full-load fractionation extraction system from a feeding level, and a 4N level magnesium nitrate solution obtained from a water phase at the 1 st level outlet of the Mg/CaPbAlFe fractionation extraction system in the step 3 enters into the LiNa/Mg full-load fractionation extraction system from the last 1 level; obtaining a lithium nitrate and sodium nitrate mixed solution containing Cl, Si and S from a1 st-stage outlet water phase of a LiNa/Mg full-load fractional extraction system; separating a balanced load P507 organic phase of a LiNa/Mg full-load fractional extraction system feeding level, and using the balanced load P507 organic phase as an extraction organic phase for separating LiNaMg/MgCaPbAlFe by full-load fractional extraction in the step 1; obtaining a P507 organic phase loaded with magnesium from the last 1-level outlet organic phase of the LiNa/Mg full-load fractional extraction system, and using the P507 organic phase as an extraction organic phase for fractional extraction and separation of Mg/CaPbAlFe in the step 3;

and step 3: fractionation, extraction and separation of Mg/CaPbAlFe

Step 3, fractionating, extracting and separating Mg/CaPbAlFe to realize the separation of magnesium from calcium, lead, aluminum and iron; taking a P507 organic phase loaded with magnesium obtained from the last level 1 of the LiNa/Mg full-load fractionation extraction system in the step 2 as an extraction organic phase, taking a P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron obtained from the last level 1 of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step 1 as a feed liquid, and taking 6.0mol/L nitric acid as washing acid; the P507 organic phase loaded with magnesium and obtained from the last 1 level of the LiNa/Mg full-load fractionation extraction system in the step 2 enters into a Mg/CaPbAlFe fractionation extraction system from the 1 st level, the P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron and obtained from the last 1 level of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step 1 enters into the Mg/CaPbAlFe fractionation extraction system from a feeding level, and 6.0mol/L nitric acid washing acid enters into the Mg/CaPbAlFe fractionation extraction system from the last 1 level; obtaining a target product of 4N-grade magnesium nitrate solution from the water phase at the 1 st grade outlet of the Mg/CaPbAlFe fractional extraction system, and taking the 4N-grade magnesium nitrate solution as a detergent of the LiNa/Mg full-load fractional extraction system in the step 2; separating a feed-grade equilibrium water phase of a Mg/CaPbAlFe fractional extraction system to be used as a detergent for separating LiNaMg/MgCaPbAlFe by full-load fractional extraction in the step 1; and obtaining a P507 organic phase loaded with calcium, lead, aluminum and iron from the last 1-stage outlet organic phase of the Mg/CaPbAlFe fractional extraction system.

2. The method for preparing a 4N grade magnesium nitrate solution according to claim 1, wherein: the P507 organic phase is a kerosene solution of P507 and TBP, wherein the concentration of the P507 is 1.0mol/L, and the concentration of the TBP is 0.05 mol/L; when used, the P507 organic phase is saponified by ammonia saponification to obtain a saponified P507 organic phase.

3. The method for preparing a 4N grade magnesium nitrate solution according to claim 1, wherein: the concentration of related elements in the magnesium nitrate concentrate solution is respectively as follows: cl 1.0-5.0 g/L, Si 0.010.010-0.030 g/L, and S0.010g/L-0.030 g/L, Li 0.10.10-0.30 g/L, Na 0.10-0.50 g/L, Mg 50.0.0 g/L-70.0 g/L, Ca 1.0.0 g/L-5.0 g/L, Pb 0.010.010-0.030 g/L, Al 0.10.10 g/L-0.50 g/L, Fe 0.10-0.30 g/L.

4. The method for preparing a 4N grade magnesium nitrate solution according to claim 1, wherein: the concentration of related elements in the 4N-grade magnesium nitrate solution is respectively as follows: cl0.00010 g/L-0.00050 g/L, Si 0.00010.00010 g/L-0.00030 g/L, S0.00010.00010 g/L-0.00030 g/L, Li 0.00010.00010 g/L-0.00030 g/L, Na 0.00010.00010 g/L-0.00050 g/L, Mg 68.0.0 g/L-72.0 g/L, Ca 0.0010.0010 g/L-0.0050 g/L, Pb 0.00010.00010 g/L-0.00030 g/L, Al 0.00010.00010 g/L-0.00030 g/L, Fe 0.00010.00010 g/L-0.00030 g/L.

Technical Field

The invention relates to a method for preparing a 4N-grade magnesium nitrate solution, in particular to a method for directly preparing the 4N-grade magnesium nitrate solution by taking a magnesium nitrate enriched solution as a feed liquid, P507 as an extracting agent and TBP as a modifier, separating and removing metal elements such as lithium, sodium, calcium, lead, aluminum, iron and the like in the feed liquid and non-metal elements such as chlorine, silicon, sulfur and the like. The invention belongs to the technical field of preparation of 4N-grade magnesium nitrate.

Background

The light-burned magnesia is the enriched magnesia (or industrial crude product) with the content of 87 to 96 percent obtained by burning magnesite, brucite, clinopodium stones, hydromagnesite, dolomite, serpentine and the like at the temperature of between 700 and 1000 ℃. Since the concentration of magnesium ions in seawater and salt lake brine is not low, the magnesium hydroxide concentrate is usually obtained by precipitating magnesium from seawater and salt lake brine with lime milk after extracting bromine and lithium. It is needless to say that the above-mentioned magnesium oxide concentrate or magnesium hydroxide concentrate is dissolved in nitric acid to obtain a magnesium nitrate concentrate solution, which is referred to as an important raw material for producing magnesium nitrate of a purity of not less than 2N grade. However, the magnesium nitrate concentrate solution contains high metal impurities such as sodium, calcium, lead, aluminum, iron and the like (the magnesium hydroxide concentrate is dissolved in nitric acid to obtain the magnesium nitrate concentrate solution with relatively high lithium content), and non-metal impurities such as chlorine, silicon, sulfur and the like. If the common conventional methods such as precipitation, adsorption and the like are adopted to separate and remove metal impurities (lithium, sodium, calcium, lead, aluminum, iron and the like) and non-metal impurities (chlorine, silicon, sulfur and the like) in the magnesium nitrate enriched solution, not only the cost of separating and removing the impurities is high, but also the purity of the magnesium nitrate can only reach 2N grade.

Therefore, no method for directly preparing 4N grade magnesium nitrate from the magnesium nitrate enriched solution exists at present. For preparing 4N-grade magnesium nitrate, the technical difficulty is to separate and remove metal impurity elements such as calcium, lead and the like in the magnesium nitrate enrichment solution. Aiming at key technical problems and technical difficulties existing in the preparation of 4N-grade magnesium nitrate, the invention establishes a method for efficiently separating metal and non-metal impurities in a magnesium nitrate concentrate solution and directly preparing the 4N-grade magnesium nitrate solution.

Disclosure of Invention

The invention provides a method for preparing a 4N-grade magnesium nitrate solution, and provides a method for directly preparing the 4N-grade magnesium nitrate solution from a magnesium nitrate enriched solution, aiming at the problem that no method for directly preparing the 4N-grade magnesium nitrate from the magnesium nitrate enriched solution exists at present.

The invention discloses a method for preparing 4N-grade magnesium nitrate solution, which takes magnesium nitrate enriched solution as feed liquid, 2-ethylhexyl phosphonic acid mono-2-ethylhexyl hexyl phosphonic acid (P507) as an extracting agent and tributyl phosphate (TBP) as a modifier, separates and removes metal elements such as lithium, sodium, calcium, lead, aluminum, iron and the like in the feed liquid, and separates and removes non-metal elements such as chlorine, silicon, sulfur and the like, and directly prepares the 4N-grade magnesium nitrate solution.

The invention relates to a method for preparing 4N-grade magnesium nitrate solution, which consists of 3 steps, namely full-load fractionation extraction separation LiNaMg/MgCaPbAlFe, full-load fractionation extraction separation LiNa/Mg and fractionation extraction separation Mg/CaPbAlFe; the extraction section of full-load fractionation extraction separation LiNaMg/MgCaPbAlFe realizes the separation of LiNaMg/CaPbAlFe, and the washing section realizes the separation of LiNa/MgCaPbAlFe; full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe takes a balanced load P507 organic phase obtained from a full-load fractionation, extraction and separation LiNa/Mg feeding level as an extraction organic phase, and a balanced water phase obtained from a fractionation, extraction and separation Mg/CaPbAlFe feeding level as a washing agent. Full-load fractionation, extraction and separation LiNa/Mg and fractionation, extraction and separation Mg/CaPbAlFe are directly connected in series; the outlet organic phase of full-load LiNa/Mg fractional extraction separation is used as the extraction organic phase of Mg/CaPbAlFe fractional extraction separation and directly enters the 1 st level of Mg/CaPbAlFe fractional extraction separation; the 1 st stage outlet aqueous phase of the fractionation, extraction and separation Mg/CaPbAlFe is used as a washing agent for full-load fractionation, extraction and separation LiNa/Mg.

The method for preparing the 4N-grade magnesium nitrate solution comprises the following 3 steps:

step 1: full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe

Step 1 is full-load fractionation, extraction and separation of LiNaMg/MgCaPbAlFe, the extraction section realizes the separation of LiNaMg/CaPbAlFe, and the washing section realizes the separation of LiNa/MgCaPbAlFe. And (3) taking a balanced load P507 organic phase obtained from the LiNa/Mg full-load fractional extraction system feeding level in the step (2) as an extraction organic phase, taking a magnesium nitrate enriched solution as a feed liquid, and taking a balanced water phase obtained from the Mg/CaPbAlFe fractional extraction system feeding level in the step (3) as a detergent. And (3) feeding the balanced load P507 organic phase obtained from the LiNa/Mg full-load fractionation extraction system feeding stage in the step (2) into a LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the 1 st stage, feeding the magnesium nitrate enriched solution into the LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the feeding stage, and feeding the balanced water phase obtained from the Mg/CaPbAlFe fractionation extraction system feeding stage in the step (3) into the LiNaMg/MgCaPbAlFe full-load fractionation extraction system from the last 1 st stage. Obtaining a magnesium nitrate solution containing Li, Na, Cl, Si and S from the water phase at the 1 st level outlet of the LiNaMg/MgCaPbAlFe full-load fractional extraction system, and using the magnesium nitrate solution as feed liquid for full-load fractional extraction separation LiNa/Mg in the step 2; and (3) obtaining a P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron from the last 1-level outlet organic phase of the LiNaMg/MgCaPbAlFe full-load fractional extraction system, and using the P507 organic phase as feed liquid for fractional extraction and separation of Mg/CaPbAlFe in the step 3.

Step 2: full-load fractionation extraction separation LiNa/Mg

And step 2, full-load fractionation, extraction and separation of LiNa/Mg, and separation and removal of metallic element impurities lithium and sodium and nonmetallic element impurities chlorine, silicon and sulfur in the magnesium nitrate solution. Taking a saponified P507 organic phase as an extraction organic phase, taking a magnesium nitrate solution containing Li, Na, Cl, Si and S obtained from a grade 1 outlet aqueous phase of a LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step 1 as a feed liquid, and taking a grade 4N magnesium nitrate solution obtained from a grade 1 outlet aqueous phase of a Mg/CaPbAlFe fractionation extraction system in the step 3 as a detergent. The saponified P507 organic phase is an extraction organic phase and enters into a LiNa/Mg full-load fractionation extraction system from the 1 st level, a magnesium nitrate solution containing Li, Na, Cl, Si and S, which is obtained from the water phase at the 1 st level outlet of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step 1, enters into the LiNa/Mg full-load fractionation extraction system from the feeding level, and a 4N level magnesium nitrate solution obtained from the water phase at the 1 st level outlet of the Mg/CaPbAlFe fractionation extraction system in the step 3 enters into the LiNa/Mg full-load fractionation extraction system from the last 1 level. Obtaining a lithium nitrate and sodium nitrate mixed solution containing Cl, Si and S from a1 st-stage outlet water phase of a LiNa/Mg full-load fractional extraction system; separating a balanced load P507 organic phase of a LiNa/Mg full-load fractional extraction system feeding level, and using the balanced load P507 organic phase as an extraction organic phase for separating LiNaMg/MgCaPbAlFe by full-load fractional extraction in the step 1; and obtaining a magnesium-loaded P507 organic phase from the last grade 1 outlet organic phase of the LiNa/Mg full-load fractional extraction system, and using the magnesium-loaded P507 organic phase as an extraction organic phase for fractional extraction and separation of Mg/CaPbAlFe in the step 3.

And step 3: fractionation, extraction and separation of Mg/CaPbAlFe

And 3, fractionating, extracting and separating Mg/CaPbAlFe to realize the separation of magnesium from calcium, lead, aluminum and iron. And (3) taking a P507 organic phase loaded with magnesium obtained from the last level 1 of the LiNa/Mg full-load fractionation extraction system in the step (2) as an extraction organic phase, taking a P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron obtained from the last level 1 of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step (1) as a feed liquid, and taking 6.0mol/L nitric acid as washing acid. And (3) the P507 organic phase loaded with magnesium obtained from the last 1 level of the LiNa/Mg full-load fractionation extraction system in the step (2) enters into the Mg/CaPbAlFe fractionation extraction system from the 1 st level, the P507 organic phase loaded with magnesium, calcium, lead, aluminum and iron obtained from the last 1 level of the LiNaMg/MgCaPbAlFe full-load fractionation extraction system in the step (1) enters into the Mg/CaPbAlFe fractionation extraction system from the feeding level, and 6.0mol/L nitric acid washing acid enters into the Mg/CaPbAlFe fractionation extraction system from the last 1 level. Obtaining a target product of 4N-grade magnesium nitrate solution from the water phase at the 1 st grade outlet of the Mg/CaPbAlFe fractional extraction system, and taking the 4N-grade magnesium nitrate solution as a detergent of the LiNa/Mg full-load fractional extraction system in the step 2; separating a feed-grade equilibrium water phase of a Mg/CaPbAlFe fractional extraction system to be used as a detergent for separating LiNaMg/MgCaPbAlFe by full-load fractional extraction in the step 1; and obtaining a P507 organic phase loaded with calcium, lead, aluminum and iron from the final level 1 outlet organic phase of the Mg/CaPbAlFe fractional extraction system, and recovering valuable elements after back extraction.

The P507 organic phase is a kerosene solution of P507 and TBP, wherein the concentration of the P507 is 1.0mol/L, and the concentration of the TBP is 0.05 mol/L. When used, the P507 organic phase is saponified by ammonia saponification to obtain a saponified P507 organic phase.

The concentration of related elements in the magnesium nitrate concentrate solution is respectively as follows: 1.0-5.0 g/L of Cl1.010-0.030 g/L of Si0.010-0.030 g/L of L, S0.010.010-0.030 g/L of Li0.10-0.30 g/L of Na0.10-0.50 g/L of Na0.0-70.0 g/L of Mg50.0 g/L of Ca1.0-5.0 g/L of Pb0.010g/L-0.030 g/L of Al0.10-0.50 g/L, Fe 0.10.10-0.30 g/L of Al0.0-0.50 g/L, Fe.

The concentration of related elements in the 4N-grade magnesium nitrate solution is respectively as follows: cl0.00010 g/L-0.00050 g/L, Si0.00010 g/L-0.00030 g/L, S0.00010.00010 g/L-0.00030 g/L, Li0.00010 g/L-0.00030 g/L, Na0.00010 g/L-0.00050 g/L, Mg68.0 g/L-72.0 g/L, Ca0.0010 g/L-0.0050 g/L, Pb0.00010 g/L-0.00030 g/L, Al0.00010g/L-0.00030 g/L, Fe 0.00010 g/L-0.00030 g/L.

The invention has the beneficial effects that: 1) 4N grade magnesium nitrate solution is directly obtained from the magnesium nitrate enrichment solution. After the 4N-grade magnesium nitrate solution is subjected to post-treatment such as concentration crystallization or precipitation, a series of 4N-grade magnesium-containing compounds such as 4N-grade magnesium nitrate crystals and 4N-grade magnesium phosphate crystals can be obtained. 2) The product purity is high, and the yield of magnesium is high: the purity of the 4N-grade magnesium nitrate solution of the target product is 99.991-99.997%, and the yield of magnesium is 96-98%. 3) The reagent consumption is less: the outlet organic phase fully loaded with LiNa/Mg separated by fractional extraction is used as the extraction organic phase for separating Mg/CaPbAlFe by fractional extraction, and directly enters the 1 st stage of separating Mg/CaPbAlFe by fractional extraction, so that the saponified alkali for separating Mg/CaPbAlFe by fractional extraction is saved. The 1 st level outlet water phase of the Mg/CaPbAlFe separation by fractional extraction is used as a washing agent for full-load LiNa/Mg separation by fractional extraction, so that the washing acid for full-load LiNa/Mg separation by fractional extraction is saved. 4) The separation efficiency is high: and 3 separation sections (full-load fractionation extraction separation LiNaMg/MgCaPbAlFe, full-load fractionation extraction separation LiNa/Mg, fractionation extraction separation Mg/CaPbAlFe) separate and remove metal impurities such as lithium, sodium, calcium, lead, aluminum, iron and the like and non-metal impurities such as chlorine, silicon, sulfur and the like in the magnesium nitrate enriched solution. 5) The process flow is short: the process for the direct preparation of 4N grade magnesium nitrate from a magnesium nitrate concentrate solution consists of 3 separate stages. Full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe and full-load fractionation, extraction and separation LiNa/Mg feeding grade to obtain a balanced load P507 organic phase as an extraction organic phase, so that the full-load fractionation, extraction and separation LiNaMg/MgCaPbAlFe does not need a saponification section; the equilibrium water phase obtained by fractionating, extracting and separating the Mg/CaPbAlFe feeding level is a detergent, so that a back-extraction section is not needed for fully loading, fractionating, extracting and separating the LiNaMg/MgCaPbAlFe. The LiNaMg/MgCaPbAlFe separated by full-load fractional extraction and the LiNa/Mg separated by full-load fractional extraction share a saponification section. The outlet organic phase loaded with LiNa/Mg separated by fractional extraction is used as the extraction organic phase for separating Mg/CaPbAlFe by fractional extraction, so that the saponification section is not needed for separating Mg/CaPbAlFe by fractional extraction. The outlet organic phase of full-load fractionation extraction separation LiNa/Mg is used as the extraction organic phase of fractionation extraction separation Mg/CaPbAlFe, so that no back-extraction section is required for full-load fractionation extraction separation LiNa/Mg. 6) The production cost is low: high separation efficiency, short process flow and less reagent consumption.

Drawings

FIG. 1: the invention discloses a process flow schematic diagram of a method for preparing 4N-grade magnesium nitrate solution.

In FIG. 1, LOP denotes the loaded organic phase; w represents a detergent; 4N Mg represents a 4N grade magnesium nitrate solution.

Detailed Description

A method for preparing a 4N grade magnesium nitrate solution according to the present invention will be further described with reference to the following specific examples.