WO2019150514A1

WO2019150514A1 - Method for producing purified magnesium salt

Info

Publication number: WO2019150514A1
Application number: PCT/JP2018/003292
Authority: WO
Inventors: 史明岡峰; 敏三木
Original assignee: 富田製薬株式会社
Priority date: 2018-01-31
Filing date: 2018-01-31
Publication date: 2019-08-08
Also published as: JPWO2019150514A1; JP6355184B1

Abstract

[Problem] To provide a method for producing a high-purity magnesium salt steadily at low cost. [Solution] A method for producing a high-purity magnesium salt, characterized in that a reaction step for the reaction of an insoluble magnesium compound-based raw material with hydrogen chloride is included, wherein the reaction step includes reacting hydrogen chloride in an amount of 2n mol (wherein n satisfies the formula: 0.00 < n ≤ 0.98) relative to 1 mol of Mg²⁺ ions contained in the raw material to produce a reaction product.

Description

Method for producing purified magnesium salt

The present invention relates to a method for producing a purified magnesium salt.

Magnesium is an element that is abundant in minerals or seawater, and is an essential mineral for animals and plants, so it is used in a wide range of applications such as foods, pharmaceuticals, feeds, and fertilizers. Among them, magnesium chloride is an indispensable compound in daily life as a typical magnesium salt in the food field such as co-minerals and tofu coagulants, as well as in the pharmaceutical field such as dialyzers for artificial kidneys. The ratio of magnesium chloride demand for renal dialysate applications is remarkably large.

The number of dialysis patients is rapidly increasing all over the world due to the increase in the elderly population and the number of diabetic patients. The dialysis population in 2030 is said to be 5.4 million. Dialysis patients maintain their lives by artificial dialysis three to four times a week, and it is a social responsibility for pharmaceutical companies to supply a large amount and a stable amount of dialysate to the market. However, when magnesium chloride is used for pharmaceutical applications, as shown in Table 1, the Japanese Pharmacopoeia Standards for Pharmaceuticals (abbreviation: external regulations), United States Pharmacopeia (abbreviation: abbreviation :) for magnesium chloride hexahydrate crystals. USP) and European Pharmacopoeia (abbreviation: EP) tripolar official standards list strict purity requirements.

For the purpose of pharmaceutical use, etc., it is necessary to produce magnesium chloride with high purity. Such magnesium chloride production methods are generally classified into the following three methods according to the type of raw material.

(1) Method of reacting with magnesium using metallic magnesium as a starting material Actually, magnesium magnesium is expensive, so anhydrous magnesium chloride obtained as a by-product of the sponge titanium production process is commercially available from a titanium manufacturer as shown in the following formula. TiCl ₄ + 2Mg → Ti + 2MgCl ₂
Since magnesium chloride produced by this production method has a high purity of the starting material, it can satisfy the purity for pharmaceutical use only by recrystallization after dissolution and filtration without passing through a special purification step.

(2) Method of recovering from seawater It is the most well-known method, and magnesium chloride hydrate (bittern (bitter juice)) is obtained as a byproduct of the process of collecting salt from seawater by ion exchange. It is often used mainly for food additives such as tofu coagulants and soil fertilizers. A method of removing an impurity having a high purity by boiling an aqueous solution and precipitating impurities having a lower solubility than magnesium chloride first.

(3) Method of reacting magnesium hydroxide and magnesium carbonate (natural ore magnesite is also often used) with hydrochloric acid or hydrogen chloride gas Except for natural ore, when magnesium hydroxide and magnesium carbonate are synthesized, It is obtained without taking in most of the impurities derived from seawater (already undergoing a purification process). Further, since the secondary salt is released into the air as water or carbon dioxide gas, magnesium chloride having a relatively high purity can be obtained by this method. For this reason, the purity of magnesium chloride naturally depends on the purity of the starting material. As a similar method, a method using a molten salt of an alkali metal chloride or an alkaline earth metal chloride as a raw material (Patent Document 1) is known.

(4) Other methods For example, a method of producing basic magnesium chloride using a magnesium chloride aqueous solution as a raw material (Patent Document 2) is known.

JP-A-2-243510 JP-A-9-221318

The method (1) is advantageous in that a high-purity product can be obtained with certainty, but is an expensive material, and its use is limited. That is, in the use of artificial kidney dialysate requiring a large amount of demand, it is an unfavorable material selection because it is contrary to the situation of medical cost reduction. Therefore, in order to satisfy the quality required for pharmaceutical use, the production method of magnesium chloride using anhydrous magnesium chloride commercially available as a by-product of the above-mentioned sponge titanium production process is the most efficient and practical Even occupies much of the domestic market.

However, currently, the production of titanium sponge is mostly made in China, Russia, Kazakhstan, and the United States, and since there are only a few companies in Japan, the proportion of reliance on imported products is high. In other words, it is easily affected by international conditions and exchange rate fluctuations. Moreover, since it is a premise that it is a by-product above all, it depends on the economic trend of the titanium industry. All of these become anxiety factors for “stable supply,” which is an important responsibility of pharmaceutical companies. In the future, in view of the background of an increase in dialysis patients, development of an alternative manufacturing method that can be stably supplied, is inexpensive, and can also satisfy standards for pharmaceutical applications is strongly desired from the manufacturing site of pharmaceuticals.

The bittern obtained by the method (2) is mostly magnesium chloride, but also contains many impurities such as sodium, potassium, calcium, sulfate and bromide. Further, by boiling to increase the purity, sodium chloride, potassium chloride, etc. having lower solubility than magnesium chloride are precipitated first, and calcium ions and sulfate ions are precipitated as calcium sulfate. It is well known that high purity magnesium chloride can be obtained.

However, there is also a refining limit in the boiled method, so only the saturated sodium chloride, potassium chloride and calcium sulfate (calcium sulfate is small but soluble in water) that is dissolved in a small amount of water on the boiled aqueous solution side cannot be completely removed. Moreover, since magnesium bromide has higher solubility than magnesium chloride, the precipitation removal itself is difficult. Therefore, although a certain degree of purity can be expected in this manufacturing method, there is no certainty in order to pass the standards shown in Table 1.

In the method (3), magnesium hydroxide and magnesium carbonate are used as raw materials, but most of the magnesium hydroxide and magnesium carbonate commercially available in Japan are based on the seawater-lime method. That is, the following reaction formula:
MgCl ₂ + Ca (OH) ₂ → Mg (OH) ₂ + CaCl ₂
Thus, magnesium hydroxide is synthesized. Magnesium carbonate is produced by blowing carbon dioxide into this magnesium hydroxide. In large-scale factories, carbon dioxide generated in the calcination process from limestone to quick lime is used effectively to reduce costs, but the tendency of impurities does not change much between magnesium carbonate and magnesium hydroxide.

When using magnesium hydroxide and magnesium carbonate by the seawater-lime method as raw materials, most of the impurities are calcium and sulfate. When magnesium chloride is produced using these as starting materials, calcium equivalent to about 3000 to 15000 ppm by weight and sulfate equivalent to 10,000 to 50000 ppm by weight coexist as impurities with respect to the weight of magnesium.

When these materials are reacted with hydrochloric acid to obtain a magnesium chloride solution, these impurities migrate to the mother liquor side by recrystallization, but complete solid dehydration is difficult during solid-liquid separation, and the recovered crystal weight On the other hand, the mother liquor adheres to about 10 to 20%, so the strict specifications in Table 1 (in the case of external regulations: calcium 100 wt ppm or less, sulfate 50 wt ppm or less (ratio to magnesium weight is not required) It is difficult to satisfy calcium 840 ppm by weight or less and sulfate 420 ppm by weight or less)).

Also, limestone-derived impurities include iron, aluminum, silicon and other trace metals. Among these, harmful trace metal impurities such as heavy metals and arsenic are already within the allowable range at the time of the starting material, and silicon can be removed by filtration because it does not elute even when reacted with hydrochloric acid. However, iron and aluminum are eluted as iron chloride, aluminum chloride and the like during the hydrochloric acid reaction, and it is difficult to comply with the standards shown in Table 1 when raw materials with poor purity are used.

On the other hand, the nigari-lime method is a well-known method for producing magnesium hydroxide. Nigari is an aqueous solution containing magnesium chloride as the main component after removing salt from seawater. The chemical reaction formula is the same as the seawater-lime method, but the remaining amount of sulfate impurities in the produced magnesium hydroxide is relatively low. There are few features. However, even in the bittern-lime method, calcium impurities are likely to remain, and when magnesium chloride is synthesized using this as a starting material, calcium impurities necessarily remain.

In addition, magnesium hydroxide obtained by suppressing the amount of lime added in the bittern-lime method, or adding caustic or ammonia water instead of lime can reduce both calcium and sulfate as impurities. , Raw material costs increase.

In the method (4), the basic magnesium chloride (Mg ₂ (OH) ₃ Cl · 4H ₂ O) can be produced, depending on the purity of the starting material, as in the case (3). Since the substance is different from the magnesium chloride hexahydrate (MgCl ₂ .6H ₂ O) used, further improvement is necessary to produce a highly pure magnesium salt.

Therefore, a main object of the present invention is to provide a method capable of stably producing a high purity magnesium salt at a low cost.

As a result of intensive studies in view of the problems of the prior art, the present inventors have found that a production method including a specific process can achieve the above object, and have completed the present invention.

That is, the present invention relates to the following method for producing a purified magnesium salt.
1. A method for producing an aqueous magnesium chloride solution, comprising:
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 ^nmol per 1 mol of Mg ²⁺ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) A method for producing a magnesium chloride aqueous solution, comprising a separation step of obtaining a magnesium chloride aqueous solution by removing sludge containing an insoluble magnesium compound present in the reaction system.
2. The ratio of iron weight (weight as Fe) to 10 ppm or less and the ratio of aluminum weight (weight as Al) to 100 ppm or less with respect to magnesium weight (weight as Mg) contained in the magnesium chloride aqueous solution, Item 2. The manufacturing method according to Item 1.
3. Item 2. The manufacturing method according to Item 1, wherein n is 0.50 ≦ n ≦ 0.98.
4). Item 2. The production method according to Item 1, wherein the magnesium content (content as Mg) contained in the insoluble magnesium compound-based raw material is 24 to 60% by weight (in terms of dry matter).
5). The insoluble magnesium compound-based raw material has a ratio of iron weight (weight as Fe) of 160 ppm or more with respect to magnesium weight (weight as Mg) contained in the raw material, and a ratio of aluminum weight (weight as Al) The manufacturing method of said claim | item 1 whose is is 160 ppm or more.
6). The content of calcium weight (as Ca) is 2000 ppm by weight or less and the content of sulfate weight (as SO ₄ ) is 2000 with respect to the weight of magnesium (weight as Mg) contained in the insoluble magnesium compound-based raw material. Item 6. The production method according to Item 5, which is not more than ppm by weight.
7). The manufacturing method of said claim | item 1 whose density | concentration of magnesium chloride aqueous solution is 10 weight% or more.
8). The manufacturing method of said claim | item 1 which further includes the washing | cleaning process including the water washing process of an insoluble magnesium compound type raw material prior to a reaction process.
9. The cleaning process
(A) a first step including a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation;
(B) An aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step is prepared, and alkali is added and mixed until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. The manufacturing method of said claim | item 8 including the 2nd process including the process of wash | cleaning the obtained solid content with water.
10. The insoluble magnesium compound-based raw material after the washing step has a calcium weight (weight as Ca) ratio of 2000 ppm or less with respect to the magnesium weight (weight as Mg) contained in the raw material, and the sulfate weight ( Item 10. The method according to Item 8 or 9, wherein the ratio of (weight as SO ₄ ) is 2000 ppm or less.
11 The insoluble magnesium compound-based raw material before passing through the washing step has a ratio of iron weight (weight as Fe) of 160 ppm or more, aluminum weight (weight as Al) to magnesium weight (weight as Mg) contained in the raw material. The ratio of weight) is 160 ppm or more, the ratio of calcium weight (weight as Ca) is 3000 ppm or more, and the ratio of sulfate weight (weight as SO ₄ ) is 10,000 ppm or more. Production method.
12 Item 2. The method according to Item 1, further comprising the step of adding aluminum chloride to the liquid phase in the reaction step.
13. A method for producing high-purity magnesium chloride,
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 ^nmol per 1 mol of Mg ²⁺ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) a separation step of obtaining an aqueous magnesium chloride solution by removing sludge containing insoluble magnesium compounds present in the reaction system;
(3) A method for producing high-purity magnesium chloride, comprising a recrystallization step of recrystallizing magnesium chloride from the aqueous solution.
14 Item 14. The method according to Item 13, wherein in the recrystallization step, the magnesium chloride aqueous solution is concentrated and recrystallized.
15. The proportion of iron weight (weight as Fe) is 10 ppm or less and the proportion of aluminum weight (weight as Al) is 50 ppm or less with respect to magnesium weight (weight as Mg) contained in the magnesium chloride aqueous solution, Item 14. The manufacturing method according to Item 13.
16. Item 14. The method according to Item 13, wherein n is 0.50 ≦ n ≦ 0.98.
17. Item 14. The production method according to Item 13, wherein the magnesium content (content as Mg) contained in the insoluble magnesium compound-based raw material is 24 to 60% by weight (in terms of dry matter).
18. The insoluble magnesium compound-based raw material has a ratio of iron weight (weight as Fe) of 160 ppm or more with respect to magnesium weight (weight as Mg) contained in the raw material, and a ratio of aluminum weight (weight as Al) Item 14. The method according to Item 13, wherein the content is 160 ppm or more.
19. The content of calcium weight (as Ca) is 2000 ppm by weight or less and the content of sulfate weight (as SO ₄ ) is 2000 with respect to the weight of magnesium (weight as Mg) contained in the insoluble magnesium compound-based raw material. Item 19. The production method according to Item 18, wherein the weight is not more than ppm.
20. Item 14. The method according to Item 13, wherein the concentration of the magnesium chloride aqueous solution is 10% by weight or more.
21. Item 14. The production method according to Item 13, further comprising a washing step including a water washing treatment of the insoluble magnesium compound-based raw material prior to the reaction step.
22. The cleaning process
(A) a first step including a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation;
(B) An aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step is prepared, and alkali is added and mixed until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. The manufacturing method of said claim | item 21 including the 2nd process including the process of wash | cleaning the obtained solid content with water.
23. The insoluble magnesium compound-based raw material after the washing step has a calcium weight (weight as Ca) ratio of 2000 ppm or less with respect to the magnesium weight (weight as Mg) contained in the raw material, and the sulfate weight ( ratio of the weight) as SO ₄ is 2000ppm or less, the production method according to the claim 21 or 22.
24. The insoluble magnesium compound-based raw material before the washing step has a ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) contained in the raw material is 160 ppm or more, and aluminum weight (Al Or 21), wherein the proportion of calcium (weight as Ca) is 3000 ppm or more, and the proportion of sulfate weight (weight as SO ₄ ) is 10,000 ppm or more. 22. The production method according to 22.
25. Item 14. The method according to Item 13, further comprising the step of adding aluminum chloride in the liquid phase in the reaction step.
26. A method for producing high-purity magnesium chloride,
(A) The magnesium content (content as Mg) is 24 to 60% by weight (in terms of dry matter), and the ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) is 160 ppm. The ratio of aluminum weight (weight as Al) is 160 ppm or more, the ratio of calcium weight (weight as Ca) is 3000 ppm or more, and the ratio of sulfate weight (weight as SO ₄ ) is 10,000 ppm. A water washing step including a step of preparing an aqueous suspension of the insoluble magnesium compound-based raw material as described above and subjecting the aqueous suspension to solid-liquid separation,
(B) A step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material that has undergone a water washing step, adding and mixing alkali until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. Alkaline washing step (C) The ratio of calcium weight (weight as Ca) is 2000 ppm or less and the ratio of sulfate weight (weight as SO ₄ ) is 2000 ppm or less with respect to magnesium weight (weight as Mg). When reacting an insoluble magnesium compound-based raw material that has undergone an alkali cleaning step with hydrogen chloride, 2 ^nmol per mol of Mg ²⁺ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98) A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(D) By removing sludge containing an insoluble magnesium compound present in the reaction system, the ratio of iron weight (weight as Mg) to magnesium weight (weight as Mg) is 10 ppm or less, and aluminum weight ( A separation step of obtaining a magnesium chloride aqueous solution having a ratio of (weight as Al) of 100 ppm or less,
(E) A method for producing high-purity magnesium chloride, comprising a step of recrystallizing magnesium chloride from the aqueous solution.

According to the present invention, it is possible to provide a method capable of stably producing a high-purity magnesium salt at a low cost.

In particular, in the reaction step, the total amount of insoluble magnesium compound in the insoluble magnesium compound-based material is not reacted, but the unreacted insoluble magnesium compound is reacted so that it remains slightly in the reaction system. Impurities can remain as solids together with unreacted insoluble magnesium compounds, and elution into the solution can be effectively suppressed. As a result, a high-purity magnesium chloride aqueous solution, and thus a high-purity magnesium chloride crystal can be produced.

It is a flowchart which shows an example of the manufacturing method of the magnesium chloride aqueous solution and magnesium chloride of this invention.

1. Manufacturing method of magnesium chloride aqueous solution The manufacturing method (1st method) of the magnesium chloride aqueous solution of this invention is the following.
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 ^nmol per 1 mol of Mg ²⁺ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) It includes a separation step of obtaining an aqueous magnesium chloride solution by removing sludge containing insoluble magnesium compounds present in the reaction system.

The insoluble magnesium compound- based material itself used in the first method of the insoluble magnesium compound-based material is not particularly limited, and known or commercially available materials can also be used. Moreover, what was obtained by the well-known manufacturing method can also be used.

As the type of the insoluble magnesium compound, a compound that is hardly soluble or insoluble in water (usually solubility in water (20 ° C.) of 1 g / 30 mL or less) can be used. For example, in addition to magnesium oxide, basic magnesium carbonate, normal magnesium carbonate, magnesium hydroxide, etc., magnesium silicate and ore include magnesite, forsterite and the like. Among these, at least one of magnesium oxide, basic magnesium carbonate, magnesium hydroxide and the like can be used from the viewpoints of cost and availability.

The magnesium content of the insoluble magnesium compound-based raw material is not particularly limited. Usually, the Mg content is 24 to 60% by weight, preferably 40 to 60% by weight, more preferably 54 to 59% by weight in terms of dry matter. %. By using the raw material in such a range, a more effective purification effect can be obtained at a lower cost. Therefore, in order to satisfy such a content, it is preferable to use magnesium oxide or a mixture containing the same as the insoluble magnesium compound.

Insoluble magnesium compound-based raw materials contain other impurities in addition to the above insoluble magnesium compounds. That is, in the present invention, by using an insoluble magnesium compound-based material as a crude material, a high-purity magnesium chloride aqueous solution and magnesium chloride (crystal) can be obtained even with an inexpensive material.

As such a raw material, from the viewpoint of easy availability and cost, for example, magnesium hydroxide by the seawater-lime method, or magnesium carbonate obtained by reacting magnesium hydroxide with carbonate ions or carbon dioxide gas is used. An insoluble magnesium compound-based raw material contained as an insoluble magnesium compound can be suitably used. Furthermore, the magnesium oxide obtained from the said magnesium hydroxide and magnesium carbonate can also be used suitably.

The above-mentioned insoluble magnesium compound-based raw materials by the seawater-lime method (hereinafter also referred to as “seawater-lime method-derived raw materials”) are a) calcium hydroxide and calcium salt, b) sulfate, c) as main impurities. Aluminum, d) iron, e) silicon and f) other trace metals are included. As described above, f) trace metals are already within the acceptable range at the time of the starting material, and e) silicon can be removed by filtration because it does not elute upon reaction with hydrochloric acid.

Therefore, impurities that can be substantially removed in the seawater-lime method-derived raw materials and the like are a) calcium hydroxide and calcium salt, b) sulfate, c) aluminum, and d) iron. More specifically, the ratio to the magnesium weight (as Mg) in the insoluble magnesium compound-based raw material is as follows: a) Calcium (as Ca) content 3000 ppm by weight or more, b) Sulfate (as SO ₄ ) content 10,000 weight It is also possible to use a raw material containing ppm or more, c) an aluminum (as Al) content of 160 wt ppm or more, and d) an iron (as Fe) content of 160 wt ppm or more.

In addition, the above-mentioned ratio is as follows: the Mg content is W (Mg), the Ca content is W (Ca), the sulfate content is W (SO ₄ ), the aluminum content is W (Al), When the content is W (Fe), [W (Ca) / W (Mg)], [W (SO ₄ ) / W (Mg)], [W (Al) / W (Mg)], [W (Fe) / W (Mg)] value (weight ratio) is shown (the same applies hereinafter).

On the other hand, when calcium hydroxide, calcium salt, and sulfate are contained in the insoluble magnesium compound-based raw material that is the starting material, these cannot be removed by the reaction step. For this reason, when these are contained more than the allowable value, in order to remove part or all of the total content of calcium hydroxide, calcium salt, and sulfate, a washing step (described later) is performed in advance before the reaction step. It is desirable to do.

The calcium component contained in the insoluble magnesium compound-based raw material is considered to be in any form of calcium salt such as calcium sulfate, calcium carbonate, etc. in addition to calcium hydroxide. Of these, calcium sulfate and calcium hydroxide dissolve in a small amount in water and are relatively easy to remove by washing with water, but calcium carbonate hardly dissolves in water. For this reason, when magnesium carbonate is used as the insoluble magnesium compound, most of the impurity calcium is often in the form of calcium carbonate, which makes it difficult to remove by washing. Therefore, it is preferable to use other insoluble magnesium compounds or to use a small amount even if they are used. In addition, when magnesium hydroxide is selected as the insoluble magnesium compound, the impurity calcium is considered to be either calcium sulfate or calcium hydroxide, but the liquid phase using magnesium hydroxide should exhibit basicity exceeding pH 10. Therefore, it becomes easy to absorb dissolved carbon dioxide and carbon dioxide in the air, and eventually, the possibility that calcium carbonate is generated increases. Therefore, it is easier to reduce the amount of calcium impurities if the amount of use is suppressed. On the other hand, in magnesium oxide, most of calcium impurities are usually calcium sulfate in many cases. This is thought to be due to the release of carbon dioxide from the calcium carbonate contained as an impurity in the firing step to make an oxide, calcium oxide, and calcium sulfate combined with sulfates in which free calcium ions coexist. . In view of these points, as the insoluble magnesium compound-based material, it is preferable to use a magnesium oxide-based material in a form in which calcium is easily removed or a material comprising a mixture containing the same.

However, since magnesium oxide generally has a higher raw material cost than magnesium hydroxide, magnesium hydroxide can be used in combination when giving priority to cost. In this case, the higher the compounding ratio of magnesium oxide, the higher the calcium removal effect. Here, the higher the compounding ratio of magnesium oxide, the higher the magnesium content (for example, Examples 12 to 13 described later). For example, if the dry matter content of magnesium hydroxide is 97% by weight, the magnesium content is 97% by weight × (24.3 (atomic weight of magnesium) /58.3 (formula weight of magnesium hydroxide)) = about 40% by weight. It becomes. On the other hand, if the dry matter content of magnesium oxide is 99% by weight, 99% by weight × (24.3 (magnesium atomic weight) /40.3 (magnesium oxide formula weight)) = about 60% by weight is calculated. Particularly preferably, the lower limit value in consideration of the target purity of the magnesium chloride to be generated can be set up to a blending ratio of about 54% by weight of magnesium (that is, about 1/4 of magnesium hydroxide).

The property (form) of the insoluble magnesium compound-based raw material is not particularly limited, but is usually preferably in the form of powder from the viewpoint of reaction operation in the production method of the present invention. When used in the form of powder, the average particle diameter is not limited, but can be appropriately set within the range of about 1 to 20 μm.

Washing Step In the present invention, the insoluble magnesium compound-based material is subjected to the reaction step, but it is preferable to perform the washing step on the insoluble magnesium compound-based material in advance prior to the reaction step. A part or all of impurities (especially calcium, sulfate, etc.) contained in the insoluble magnesium compound-based raw material can be removed by the washing process, so that a higher-purity aqueous solution, and thus higher-purity magnesium chloride can be more reliably obtained. It becomes possible to provide.

The washing step is not particularly limited as long as the content of impurities as described above can be reduced, but usually a method including a water washing treatment of an insoluble magnesium compound-based raw material may be employed.

For example, in the present invention, it is preferable to carry out the following cleaning process.
(A) a first step including a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation;
(B) An aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step is prepared, and alkali is added and mixed until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. It is preferable to perform a washing step including a second step including a step of washing the obtained solid content with water.

In particular, both the calcium salt and the sulfate can be more reliably removed by the above method. That is, after first removing the calcium salt mainly in the first step, the sulfate is removed by heat solubilization in the presence of an alkali in the second step, followed by solid-liquid separation and washing with solids. It is desirable to carry out a washing process including steps.

First Step The first step includes a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation. In the first step, mainly water-soluble impurities (for example, calcium ions and sulfate ions) can be removed.

In the first step, an aqueous suspension can be prepared by using a powdery insoluble magnesium compound-based raw material and dispersing it in water. The amount of dispersion in this case can be appropriately set according to the type of insoluble magnesium compound, the particle size, etc., but it is usually sufficient that the solid content is about 5 to 40% by weight. For example, as an insoluble magnesium compound-based material, any one of magnesium oxide, magnesium hydroxide and magnesium carbonate, or a mixture containing two or more thereof, preferably magnesium oxide alone, the magnesium content is 24 to 60% by weight in terms of dry matter. The resulting powdery solid or its aqueous slurry is dispersed or suspended in water and then decanted or washed with filtered water to elute and remove some or all of the water-soluble impurities. Although most of the water-soluble impurities are calcium ions and sulfate ions, it is not necessary to completely remove sulfate ions at this stage, so it is preferable to wash with water until almost no calcium ions are detected in the washing solution.

The water suspension is subjected to stirring or the like as required, and then the raw material is recovered by solid-liquid separation. The solid-liquid separation method itself may follow a known method. For example, a known method such as pressure filtration, vacuum filtration, vacuum filtration, natural filtration, centrifugal filtration, or the like can be employed. It is only necessary to separate solids present in the suspension, and the degree of separation is not particularly limited. For example, a) a method of continuously replacing a semi-sedimented supernatant solution like a thickener, b) a method of continuously filtering by adding pressure while diluting the suspension by adding water, etc. May be. At this time, for example, a known or commercially available device such as a filter press or a centrifuge can be used.

In the first step, a series of steps including preparation of the aqueous suspension and solid-liquid separation may be repeated twice or more as necessary. Moreover, you may further wash with the said raw material (solid content) collect | recovered by solid-liquid separation as needed.

In the first step, calcium and sulfate are mainly removed. As a ratio with respect to magnesium weight (as Mg) in the insoluble magnesium compound-based raw material, for example, a) calcium (as Ca) content 2500 ppm by weight or more, b) It is preferred that a sulfate (as SO ₄ ) content of 7000 ppm by weight or more is removed.

As a result of the removal of calcium and sulfate, in particular, the raw material after the first step has a ratio to the magnesium weight (as Mg) in the insoluble magnesium compound-based raw material, for example, a) calcium (as Ca) content of 2000 ppm by weight or less B) Sulfate (as SO ₄ ) content 20000 ppm by weight or less, c) Aluminum (as Al) content 160 ppm by weight or more, d) Iron (as Fe) content 160 ppm by weight or more preferable.

Second Step The second step is to prepare an aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step, add and mix alkali until the aqueous suspension reaches pH 12 to 14, and heat. A step of washing the solid content obtained by solid-liquid separation later with water is included.

In the present invention, as the second step, a method of heat-extracting the hardly soluble sulfate under high alkalinity and then removing by washing with water is taken, but the most important point is that the second step is carried out after sufficiently removing calcium impurities. It is to be. That is, the cleaning process has two stages, and the order is important. If the second step is carried out without sufficiently removing calcium impurities, the remaining calcium is dissolved in water or absorbs carbon dioxide in the air under high alkalinity, so that calcium removal is performed to produce insoluble calcium carbonate. It becomes difficult. For this reason, it is necessary to perform a 2nd process with respect to the insoluble magnesium compound type raw material after passing through a 1st process to the last.

Therefore, in the second step, after sufficiently removing calcium impurities in the first step, heat extraction is performed under high alkalinity in order to further remove sulfates. In the first step, most of the sulfate can be removed, but this is a soluble sulfate bound as calcium sulfate, and a portion of the sulfate remains as poorly soluble basic magnesium sulfate. In order to bring the sulfates of the standards shown in Table 1 to acceptable levels, it is desirable to remove them in the second step.

Preparation of the water suspension can be performed in the same manner as in the first step. And an alkali is added and mixed with respect to the obtained water suspension. Various alkalis such as potassium hydroxide, sodium hydroxide, ammonia, lithium hydroxide, sodium silicate, etc. can be used as the alkali to be used. However, magnesium chloride is used as a dialysis agent, especially from the viewpoint of avoiding the chance of contamination. It is preferable to use sodium hydroxide as the alkali from the standpoint that it can be used for the like. Further, the alkali can be added in the form of a solid or an aqueous solution thereof.

The amount of alkali added may be an amount added so that the pH of the aqueous suspension is within the range of 12-14. That is, in order to sufficiently remove sulfate, heating in a highly alkaline state at pH 12 to 14 (concentration equivalent to 0.01 to 1 mol / L as OH) is required. In particular, the higher the alkali concentration, the higher the sulfate removal effect. However, in consideration of raw material costs, wastewater neutralization costs, material handling due to increased viscosity, the pH is preferably about 12 to 13.

After adding alkali, heat the water suspension. The insoluble sulfate can be solubilized by heating in the presence of alkali. The heating temperature is usually about 50 to 95 ° C., preferably 70 to 95 ° C. The heating time can be appropriately set according to the heating temperature or the like, but generally it may be set within a range of about 1 to 10 hours.

After heating, the water suspension is cooled as necessary, and then the raw material is recovered by solid-liquid separation. The solid-liquid separation method may be the same as in the first step. In the second step, a series of steps including preparation of aqueous suspension, addition of alkali, mixing and heating, and solid-liquid separation may be repeated twice or more for the recovered raw material as necessary.

Next, the solid content obtained by the above solid-liquid separation is washed with water. Thereby, especially the alkali adhering in the second step can be removed. The method of washing with water may follow a known method, and for example, various methods such as a method of preparing a water suspension and performing solid-liquid separation, and a method of pouring water onto a raw material placed on a filter paper can be adopted. it can.

Reaction Step In the reaction step, when reacting the insoluble magnesium compound-based raw material with hydrogen chloride, 2 nmol (where n is 0.00 <n ≦ 0.98) with respect to 1 mol of Mg ²⁺ ions contained in the raw material. The reaction product is obtained by reacting with hydrogen chloride.

In the present invention, particularly through the reaction with hydrogen chloride in the reaction step, particularly Fe and Al can be effectively removed. Therefore, in the present invention, as an insoluble magnesium compound-based raw material to be used in the reaction step, the ratio of the weight of iron (weight as Mg) to the weight of magnesium contained in the raw material (weight as Fe) is 160 ppm by weight or more. It is also possible to use a raw material whose aluminum weight (weight as Al) is 160 ppm by weight or more.

The ratio of the calcium content and the sulfate content to the magnesium weight (weight as Mg) contained in the raw material is not particularly limited, but the calcium (as Ca) content is 2000 ppm by weight or less, sulfate (SO ₄ ) The content is preferably 2000 ppm by weight or less. Thereby, high purity magnesium chloride aqueous solution and high purity magnesium chloride can be obtained more reliably. That is, in the present invention, even if a crude material containing a relatively large amount of Fe and Al as impurities is used, in the present invention, a high-purity magnesium chloride aqueous solution, and thus high-purity magnesium chloride can be produced.

The reaction step may be performed in any of a gas phase, a liquid phase, and the like, but is preferably performed in a liquid phase. The liquid phase (solvent) in the case of carrying out in the liquid phase is not limited, but usually water may be used. The water may be tap water, industrial water or the like, but pure water or ultrapure water is preferred. Accordingly, for example, ion exchange water, distilled water, and the like can also be suitably used.

The insoluble magnesium compound-based material is preferably dispersed in the liquid phase. In this case, it is preferable to disperse the insoluble magnesium compound-based raw material in the liquid phase before reacting with hydrogen chloride. For example, the aqueous suspension obtained in the second step of the washing step can be used as it is. It is also possible to disperse the insoluble magnesium compound-based material in hydrochloric acid.

As the hydrogen chloride to be added, a known or commercially available one can be used. In addition, any of hydrogen chloride obtained by various production methods can be used. In particular, since hydrochloric acid obtained by synthesizing chlorine and hydrogen obtained as by-products when sodium hydroxide is produced by a salt electrolysis method can be obtained with high purity and relatively inexpensively, such hydrogen chloride can also be suitably used. .

Hydrogen chloride is usually used in the form of an aqueous solution (that is, hydrochloric acid), but is not limited thereto. For example, a method of reacting gaseous hydrogen chloride (or a separate action of chlorine gas and hydrogen gas) directly with an insoluble magnesium compound-based material is also possible. Thereby, the magnesium chloride aqueous solution can be obtained at a higher concentration.

In the reaction between the insoluble magnesium compound-based material and hydrogen chloride, 2 nmol (where n satisfies 0.00 <n ≦ 0.98) with respect to 1 mol of Mg ²⁺ ions contained in the material. React with hydrogen. That is, the reaction is carried out so that the unreacted insoluble magnesium compound remains by reacting all 2 nmoles of hydrogen chloride. Thereby, it is possible to effectively suppress the elution of impurities (ions) in the liquid phase by confining as much impurities as possible contained in the insoluble magnesium compound-based raw material in the unreacted insoluble magnesium compound.

The n satisfies 0.00 <n ≦ 0.98, particularly preferably satisfies 0.50 ≦ n ≦ 0.98, and more preferably satisfies 0.67 ≦ n ≦ 0.90. When n exceeds 0.98, impurities may elute in the liquid phase and remain in the magnesium chloride aqueous solution.

For example, by controlling the above n, the reaction can proceed with the following reaction formula.
MgOR + 2n (HCl) → nMgCl ₂ + (1-n) MgOR + by-product [wherein, MgOR is magnesium oxide (MgO), magnesium hydroxide (Mg (OH) ₂ ), basic magnesium carbonate (aMgCO ₃ .Mg (OH) ₂ · nH ₂ O (a is 3 to 5)) and magnesite (MgCO ₃ ), n satisfies 0.00 <n ≦ 0.98, and the by-product is Water (H ₂ O) and / or carbon dioxide (CO ₂ ). ]

In the above reaction formula, when n ≧ 1, it means that all MgO has reacted, and when n> 1, it means that excess HCl other than MgCl ₂ remains. Under this condition, Fe and Al contained in the insoluble magnesium compound are eluted as chlorides, and as a result, they coexist in the magnesium chloride aqueous solution as impurities.

On the other hand, when n <1, especially 0.98 or less, it is obtained by removing sludge (residue) which is solid content in a state where 67 to 98% of MgO is reacted with HCl. In the magnesium chloride aqueous solution, Fe, Al, and the like contained in the insoluble magnesium compound remain in the sludge. As a result, a magnesium chloride aqueous solution that does not contain these impurities can be obtained. That is, if the unreacted insoluble magnesium compound is only slightly suspended, the effect of removing Fe and Al is sufficiently observed. However, since it is preferable that the amount of unreacted insoluble magnesium compound is as small as possible, it is desirable to set it within the range of n as described above. In the control operation at the mass production level, the risk of mixing impurities increases as much as n = 1. On the other hand, if too much insoluble magnesium salt is left in consideration of quality safety, a) the material handling property of filtration removal is burdened, b) the volume of sludge cake is large and its water loss is large, c ) The load on productivity is large and unrealistic as the obtained magnesium chloride aqueous solution is thin. For this reason, it is desirable to control so that the range of n falls within the above range.

In the reaction step, aluminum chloride can be added to the liquid phase as necessary. By adding aluminum chloride, separation in a sludge cake separation step, which is a subsequent step, is facilitated. That is, in the present invention, aluminum chloride functions as a so-called filter aid. Known or commercially available aluminum chloride can be used.

The timing of addition of aluminum chloride is not particularly limited, and may be any stage before addition of hydrogen chloride (before reaction), simultaneously with hydrogen chloride, after addition of hydrogen chloride, or the like. The amount of aluminum chloride added is not particularly limited, but generally the weight ratio of aluminum to the weight of magnesium contained in the sludge is about 0.02 to 0.2% by weight (Al / Mg weight ratio = 0.0.0). If it is about 02 to 0.2), an effect on filterability can be obtained, and since it reacts with magnesium in sludge and is insolubilized, elution of aluminum into the magnesium chloride aqueous solution can be prevented.

Separation process In the separation process, an aqueous magnesium chloride solution is obtained by removing sludge containing an insoluble magnesium compound present in the reaction system.

In the reaction step, the reaction is carried out so that unreacted insoluble magnesium compound remains, and therefore sludge containing the insoluble magnesium compound exists as a solid content in the reaction system (particularly in the liquid phase). That is, the sludge coexists in a high purity magnesium chloride aqueous solution. Therefore, in the separation step, the sludge is removed and the magnesium chloride aqueous solution is recovered.

The separation method is not limited as long as the sludge can be removed. For example, a known method such as pressure filtration, vacuum filtration, vacuum filtration, natural filtration, or centrifugal filtration may be employed. In this case, for example, a known or commercially available device such as a filter press or a centrifuge can be used.

Thus, in the separation step from the reaction step, mainly aluminum and iron are removed, but as a ratio with respect to the magnesium weight (as Mg) in the insoluble magnesium compound-based raw material, for example, c) aluminum (as Al) content 100 weight ppm As described above, it is preferable that d) iron (as Fe) content of 150 ppm by weight or more is removed.

In the magnesium chloride aqueous solution thus obtained, as a result of removal of aluminum and iron in particular, the ratio to the magnesium weight (as Mg) in the aqueous solution is, for example, a) Calcium (as Ca) content of 2000 ppm by weight or less B) Sulfate (as SO ₄ ) content 2000 ppm by weight or less, c) Aluminum (as Al) content 100 wt ppm or less, d) Iron (as Fe) content 10 ppm by weight or less preferable.

The magnesium chloride aqueous solution can be used as a raw material for producing magnesium chloride as it is or after adjusting its concentration. The concentration of the obtained aqueous magnesium chloride solution is not particularly limited, but usually the magnesium chloride concentration can be 10 wt% or more (particularly 10 to 30 wt%) as magnesium chloride anhydride. Therefore, for example, it can be set within a range of 15 to 20% by weight.

2. Production method of high purity magnesium chloride The production method (second method) of high purity magnesium chloride of the present invention comprises:
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 ^nmol per 1 mol of Mg ²⁺ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) a separation step of obtaining an aqueous magnesium chloride solution by removing sludge containing insoluble magnesium compounds present in the reaction system;
(3) It includes a recrystallization step of recrystallizing magnesium chloride from the aqueous solution.

The second method is a method including a step of recrystallizing the magnesium chloride aqueous solution obtained by the first method, whereby desired high purity magnesium chloride can be obtained. Therefore, the reaction step and the separation step in the second method can be performed in the same manner as in the first method. Moreover, it can implement similarly to a 1st method also about a washing | cleaning process. Hereinafter, each step of the second method will be described.

The insoluble magnesium compound- based material itself used in the second method of the insoluble magnesium compound-based material is not particularly limited, and known or commercially available materials can also be used. Moreover, what was obtained by the well-known manufacturing method can also be used.

The magnesium content of the insoluble magnesium compound-based material is not particularly limited, but is usually 24 to 60% by weight, preferably 40 to 60% by weight (especially 54 to 59% by weight) in terms of dry matter as the Mg content. It is preferable. By using the raw material in such a range, a more effective purification effect can be obtained at a lower cost. Therefore, in order to satisfy such a content, it is preferable to use magnesium oxide or a mixture containing the same as the insoluble magnesium compound.

The above-mentioned insoluble magnesium compound-based raw materials by the seawater-lime method (hereinafter also referred to as “seawater-lime method-derived raw materials”) are a) calcium hydroxide and calcium salt, b) sulfate, c) as main impurities. Aluminum, d) iron, e) silicon and f) other trace metals are included. As noted above, f) trace metals are already within acceptable limits at the time of the starting material, and e) silicon can be removed by filtration because it does not elute upon reaction with hydrochloric acid.

In the first step, an aqueous suspension can be prepared by using a powdery insoluble magnesium compound-based raw material and dispersing it in water. The dispersion amount in this case can be appropriately set according to the type, particle size, etc. of the insoluble magnesium compound, but is usually about 5 to 40% by weight. For example, as an insoluble magnesium compound-based material, any one of magnesium oxide, magnesium hydroxide and magnesium carbonate, or a mixture containing two or more, preferably magnesium oxide alone, the magnesium content is 24 to 60% by weight in terms of dry matter The powdered solid or the aqueous slurry thereof is dispersed or suspended in water and then decanted or washed with filtered water to elute and remove some or all of the water-soluble impurities. Although most of the water-soluble impurities are calcium ions and sulfate ions, it is not necessary to completely remove sulfate ions at this stage, so it is preferable to wash with water until almost no calcium ions are detected in the washing solution.

Second Step The second step is to prepare an aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step, add and mix alkali until the aqueous suspension reaches pH 12 to 14, and heat. A step of washing the solid content with water later is included.

Next, the solid content obtained by the above solid-liquid separation is washed with water. Thereby, especially the alkali adhering in the second step can be removed. The method of washing with water may be in accordance with a known method, for example, a method of preparing a water suspension for solid-liquid separation by preparing a water suspension and solid-liquid separation, water injection to a raw material placed on a filter paper Various methods, such as a method to do, can be adopted.

The ratio of the calcium content and the sulfate content to the magnesium weight (weight as Mg) contained in the raw material is not particularly limited, but the calcium (as Ca) content is 2000 ppm by weight or less, sulfate (SO ₄ ) The content is preferably 2000 ppm by weight or less. Thereby, high purity magnesium chloride aqueous solution and high purity magnesium chloride can be obtained more reliably. That is, in the present invention, even if a crude material containing a relatively large amount of Fe and Al as impurities is used, a high-purity magnesium chloride aqueous solution, and thus high-purity magnesium chloride can be produced in the present invention.

For example, by controlling the above n, the reaction can proceed with the following reaction formula.
MgOR + 2n (HCl) → nMgCl ₂ + (1-n) MgOR + by-product [wherein, MgOR is magnesium oxide (MgO), magnesium hydroxide (Mg (OH) ₂ ), basic magnesium carbonate (aMgCO ₃ .Mg (OH) ₂ · nH ₂ O (a is 3 to 5)) and magnesite (MgCO ₃ ), n satisfies 0 <n ≦ 0.98, and the by-product is water ( H ₂ O) and / or carbon dioxide (CO ₂ ). ]

On the other hand, when n <1, especially 0.98 or less, it is obtained by removing sludge (residue) which is solid content in a state where 67 to 98% of MgO is reacted with HCl. In the magnesium chloride aqueous solution, Fe, Al, and the like contained in the insoluble magnesium compound remain in the sludge. As a result, a magnesium chloride aqueous solution that does not contain these impurities can be obtained. That is, if the unreacted insoluble magnesium compound is slightly suspended, the effect of removing Fe and Al is sufficiently observed. However, since it is preferable that the amount of unreacted insoluble magnesium compound is as small as possible, it is desirable to set it within the range of n as described above. In the control operation at the mass production level, the risk of mixing impurities increases as much as n = 1. On the other hand, if too much insoluble magnesium salt is left in consideration of quality safety, a) the material handling property of filtration removal is burdened, b) the volume of sludge cake is large and its water loss is large, c ) The load on productivity is large and unrealistic as the obtained magnesium chloride aqueous solution is thin. For this reason, it is desirable to control so that the range of n falls within the above range.

In the reaction step, aluminum chloride can be added to the liquid phase as necessary. By adding aluminum chloride, separation in a separation step, which is a subsequent step, is facilitated. That is, in the present invention, aluminum chloride functions as a so-called filter aid. Known or commercially available aluminum chloride can be used.

In the reaction step, the reaction is carried out so that unreacted insoluble magnesium compound remains, so that sludge containing the insoluble magnesium compound exists as a solid content in the reaction system (particularly in the liquid phase). That is, the sludge coexists in a high purity magnesium chloride aqueous solution. Therefore, in the separation step, the sludge is removed and the magnesium chloride aqueous solution is recovered.

The concentration of the obtained magnesium chloride aqueous solution is not particularly limited, but usually the magnesium chloride concentration can be 10% by weight or more (particularly 10 to 30% by weight) as magnesium chloride anhydride. Therefore, for example, it can be set within a range of 15 to 20% by weight.

In the recrystallization step, magnesium chloride is recrystallized from the aqueous solution. In particular, when magnesium chloride is used for food additives, pharmaceutical applications, etc., it is necessary to commercialize it as a solid (usually equivalent to hexahydrate) combined with crystal water.

In the present invention, high-purity magnesium chloride is prepared from a magnesium chloride aqueous solution. For example, 1) a method of directly drying the aqueous solution to a solid, 2) a method of concentrating to supersaturation, and then separating a precipitate into a solid-liquid separation, etc. However, it is desirable to adopt the above method 2) in that it can be purified more reliably.

The recrystallization method itself can be carried out according to a known method. For example, a) a step of obtaining a concentrate by concentrating a magnesium chloride aqueous solution (magnesium chloride aqueous solution obtained through the separation step); b) cooling the concentrate and recrystallizing the magnesium chloride using a difference in solubility depending on temperature. The method including the process to make can be implemented.

In the step a), concentration by heating can be suitably employed. The heating temperature is not limited, but is usually about 60 to 100 ° C. The degree of concentration is not particularly limited, but usually the magnesium chloride concentration can be appropriately set within a range of 35 wt% or more (particularly 37 to 40 wt%) as magnesium chloride anhydride. Therefore, for example, it can be set within the range of 38 to 39% by weight.

In the step b), the concentrated liquid heated in the a) is cooled. Cooling is usually performed to room temperature (usually 10 to 30 ° C.), where magnesium chloride crystals are precipitated.

The crystals precipitated in the step b) are collected by solid-liquid separation. The solid-liquid separation method itself may follow a known method. For example, a known method such as pressure filtration, vacuum filtration, vacuum filtration, natural filtration, centrifugal filtration, or the like can be employed. At this time, for example, a known or commercially available device such as a filter press or a centrifuge can be used.

3. High Purity Magnesium Chloride Magnesium chloride obtained by the production method of the present invention usually has a granular form consisting of crystal grains of magnesium chloride hydrate. When it is granular, its average particle size can be usually about 200 to 800 μm, but is not limited thereto.

The magnesium chloride may be anhydrous, but generally has a hydrate form, hexahydrate, dihydrate, tetrahydrate, octahydrate depending on the precipitation temperature, A 12 hydrate etc. are illustrated. In the present invention, hexahydrate (MgCl ₂ · 6H ₂ O) that can be applied to pharmaceuticals and the like is preferable.

The magnesium chloride hexahydrate has a magnesium content of about 12% by weight (especially 11.8 to 12.1% by weight in the pharmaceutical standard), and the ratio to the magnesium weight (as Mg) is, for example, a) calcium ( (As Ca) content 400 wt ppm or less, preferably 200 wt ppm or less, b) sulfate (as SO ₄ ) content 400 wt ppm or less, preferably 300 wt ppm or less, c) aluminum (as Al) content 20 Weight ppm or less, d) Iron (as Fe) content is 5 weight ppm or less. Moreover, the ratio of content of other metals is usually less than 3 ppm by weight.

Such high-purity magnesium chloride is suitably used for various chemicals such as pharmaceuticals, quasi drugs, foods and drinks (including functional foods, food additives, etc.), cosmetic feeds, fertilizers, and the like. be able to. In particular, it can be suitably used as a raw material for dialyzing agents for artificial dialysis.

Hereinafter, examples and comparative examples will be shown to describe the features of the present invention more specifically. However, the scope of the present invention is not limited to the examples. In the examples, “%” and “ppm” mean “wt%” and “wt ppm”, respectively.

In addition, the analysis evaluation method in an Example and a comparative example is as follows.
(1) Calcium test method Atomic absorption; measured by a calibration curve method. The calcium standard solutions were prepared at 0 mg / L, 0.5 mg / L, and 1.0 mg / L, and the sample concentration was adjusted to be in the same range. The insoluble sample was dissolved in an equivalent amount of hydrochloric acid.

(2) Sulfate test method The test method listed in the official document shown in Table 1 is an in-limit test, and comparative evaluation of numerical values is difficult to understand. For this reason, in this example and a comparative example, a dilution series of a standard solution was prepared, and turbidity was measured with a spectrophotometer wavelength of 610 nm. A calibration curve was created from the numerical values, and the measured values were expressed as numerical results using the calibration curves.
<Preparation reagent>
a) Aqueous sulfuric acid solution: 50 mg of concentrated sulfuric acid was diluted with 1 L of water (according to preparation method EP)
b) Barium chloride dihydrate solution: 250 g of barium chloride dihydrate was dissolved in water to make 1 L.
c) Acetic acid test solution: 30 g of acetic acid was diluted with water to make a total volume of 100 mL.
<Sample solution preparation>
(Sample solution)
In a graduated test tube, a liquid volume (range of reference liquid) according to the sulfate ion concentration in magnesium chloride was mixed with 0.5 mL of the liquid c) to make a total volume of 10 mL.
(Reference solution)
In each of three graduated test tubes, 0 mL (empty), 1 mL, and 2 mL of the liquid a) and 0.5 mL of the liquid c) were mixed to make a total volume of 10 mL.
<Measurement>
2 mL each of the mixed liquid (volume ratio 1: 3) of the liquid a) and liquid b) was added to the sample liquid and the reference liquid and shaken. After 15 to 20 minutes, the absorbance (white turbidity) was measured at a spectrophotometer wavelength of 610 nm. The measured absorbance value was converted by Excel using a calibration curve formula to obtain the value.

(3) Iron test method This test is performed in accordance with the external standard magnesium chloride hydrate test method, but it is an in-limit test, similar to sulfates. After measuring the absorbance of the photometer OD490, a calibration curve was prepared and the measured values were shown as numerical results using this.

(4) Aluminum Test Method The aluminum test method is performed according to the test method of USP “Magnesium Chloride” Aluminum, but the sample amount is adjusted according to the impurity value (frameless atomic absorption calibration curve method).

(5) Content test method The test was conducted according to the external standard magnesium chloride hydrate test method.

(6) Test method of magnesium content (in dry matter equivalent) contained in insoluble magnesium compound-based raw material When the insoluble magnesium compound is magnesium oxide, it is performed according to the content test method of USP “Magnesium Oxide”. The test was conducted without performing strong heat treatment, and the content as a solid was determined.
Further, in the case of magnesium hydroxide, the content was tested according to the content test method of USP “Magnesium Hydroxide”, but the test was performed without performing the pretreatment drying treatment, and the content as solid was obtained. After calculating the content as solid, the magnesium content (in terms of dry matter) was determined according to the following formula.

Magnesium content (dry matter equivalent) (%) = solid content (%) ÷ (100-weight loss on drying (sample 1g, decrease after 2 hours at 105 ° C) (%)) x 100

Examples 1 to 11 and Comparative Examples 1 and 2
A 1 L aqueous suspension of 100 g (magnesium content 58.4%) of USP heavy magnesium oxide powder manufactured by Tomita Pharmaceutical Co., Ltd. was suction filtered with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 150 mm). The top cake was washed 4 times with 1 L water (4 L total). The fourth washing solution was sampled at 100 mL, added with 5 mL of 8 mol / L potassium hydroxide aqueous solution, and then added with NN indicator. As a result, since the cleaning liquid was blue, it was confirmed that the calcium ion elution cleaning was completed.

Subsequently, after the cake on the filter paper was collected, it was resuspended in water to prepare an aqueous suspension, and 4 g of sodium hydroxide was dissolved in the aqueous suspension to make the final liquid volume 1 L (pH 13). The aqueous suspension was covered so as not to evaporate and then heated with stirring. After the temperature was raised to 90 ° C., the suspension was held at 90 ± 2 ° C. for 3 hours. After cooling, the suspension was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 150 mm), and the cake on the filter paper was washed 4 times with 1 L of water (4 L in total). When 20 mL of the 4th washing solution was placed in a Nessler tube, 1 mL of 10% hydrochloric acid was added, and then 2 mL of an aqueous solution of barium chloride dihydrate (250 g of barium chloride dihydrate dissolved in water to make 1 L) was added No cloudiness was observed. From this, it was confirmed that elution removal of sulfate ions was completed. The cake on the filter paper was collected and resuspended in water to obtain 370 g of a water-purified suspension of insoluble magnesium compound. The solid content ratio at this time was 9.829% in terms of magnesium content. Table 2 shows the ratio of the impurity content to the magnesium content in the purified water suspension.

Next, the water-washed purified suspension was dispensed into 13 tubes of about 20 mL each with a stoppered Nessler tube with a stopper, and the suspension weight obtained by subtracting the empty weight was determined.

Next, synthetic hydrochloric acid (manufactured by Toa Gosei Co., Ltd., HCl content: 35.59%) was added, a Nessler tube was inserted into ice water, allowed to react with occasional shaking while cooling, and 10 minutes after adding hydrochloric acid. I left it alone. In this case, in Examples 1 to 8, hydrochloric acid was added stepwise so that n was in the range of 0.50 to 0.98. In Examples 9 to 11 and Comparative Examples 1 and 2, hydrochloric acid was added so that n was 1.0 and 0.99 (the solution was dissolved together with yellow coloring), and then Examples 9 to 11 were added. In Comparative Example 2, a small amount of the suspension was added until it became slightly turbid (n was in the range of 0.98 to 0.99), while in Comparative Example 1, it was left as a solution (n Remains 1.0).

After each liquid was allowed to stand overnight, the supernatant was subjected to syringe filtration (Millipore Pyrex, Millipore PES, pore size 0.45 μm), which was used as a sample solution.

The magnesium content of each sample solution was measured, and thereafter the content and removal amount of iron (as Fe) and aluminum (as Al) were measured and calculated as a ratio to the magnesium content (as Mg). The results are shown in Table 3.

Examples 12-13
Combined with Tomita Pharmaceutical Co., Ltd. USP heavy magnesium oxide powder (59% as a magnesium content dry product) and Tomita Pharmaceutical Co., Ltd. USP heavy magnesium hydroxide powder (40.4% as a magnesium content dry product), or The powder was weighed as a single powder, and the weight corresponding to 60 g of magnesium was used as the powder sample.

In addition, the calcium content of the impurities contained in USP heavy magnesium oxide powder manufactured by Tomita Pharmaceutical Co., Ltd. is 8000 ppm, and the sulfate content is 20000 ppm (both are values converted to a ratio per weight of magnesium (as Mg)).

On the other hand, the calcium content of impurities contained in the USP heavy magnesium hydroxide powder manufactured by Tomita Pharmaceutical Co., Ltd. was 13000 ppm, and the sulfate content was 32000 ppm (both values converted to a ratio per weight of magnesium (as Mg)).

After suspending each sample in water to make 1 L, the aqueous suspension was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 150 mm), and the cake on the filter paper was 4 with 1 L of water. Washed once (total 4L). 100 mL of the 4th cleaning solution was sampled, 5 mL of 8 mol / L potassium hydroxide aqueous solution was added, and then an NN indicator was added. As a result, the cleaning solution turned blue. From this, it was confirmed that the calcium ion elution cleaning was completed.

Each of the washed cakes was suspended in water and dissolved in hydrochloric acid, and the resulting solution was subjected to syringe filtration (Millipore Pyrex, pore size 0.45 μm), which was used as a sample solution. The ratio of the impurity content of each sample solution as Ca and SO ₄ to magnesium (as Mg) dissolved in the sample solution was determined. The results are shown in Table 4.

Examples 14 to 16
500 g of USP heavy magnesium oxide powder manufactured by Tomita Pharmaceutical Co., Ltd., the same as that used in Example 12, was weighed and suspended in 5 L of water. Next, the obtained aqueous suspension was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 300 mm), and the cake on the filter paper was washed four times with 5 L of water (20 L in total). 100 mL of the 4th cleaning solution was sampled, 5 mL of an 8 mol / L potassium hydroxide aqueous solution was added, and then an NN indicator was added. As a result, the cleaning solution was blue. From this, it was confirmed that the calcium ion elution cleaning was completed.

The entire cake on the filter paper was washed with water and suspended to obtain a suspension with a feed amount of 2258 g. The solid content ratio was 12.65% as the magnesium content. In addition, the calcium impurity and sulfate impurity contents were measured, and the ratio to the magnesium (as Mg) in the suspension was determined. As a result, Ca was 670 ppm and SO ₄ was 2500 ppm.

Put 440g of this suspension evenly into a 1L container with a polypropylene lid, take 5 pieces, add a predetermined amount of sodium hydroxide to each, adjust the liquid volume to 500mL, and seal it at 90 ° C in a sealed state. It put into the thermostat. The sample was taken out every 30 minutes and treated for a total of 4 hours while shaking and degassing.

After the treatment, each liquid was cooled and then suction filtered with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 150 mm), and the cake on the filter paper was washed 4 times with 1 L of water (4 L in total). When 20 mL of the 4th washing solution was put into a Nessler tube, 1 mL of 10% hydrochloric acid was added, and then 2 mL of an aqueous solution of barium chloride dihydrate (an aqueous solution in which 250 g of barium chloride dihydrate was dissolved in water to make 1 L) was added No cloudiness was observed (confirmation that elution removal of sulfate ions had been completed). The cake on the filter paper was collected, resuspended in water, and the water-washed purified suspension of the insoluble magnesium compound was completely dissolved in hydrochloric acid. Then, 20 mL of the solution was syringe filtered (Millipore Pyrex, pore size 0.45 μm), This was used as a sample solution. The content of Ca and SO _{4 in} each sample solution was determined as a ratio with respect to magnesium (as Mg) dissolved in the sample solution. The results are shown in Table 5.

Examples 17-19
415 g of USP Heavy Magnesium Oxide Powder manufactured by Tomita Pharmaceutical Co., Ltd. and 135 g of USP Heavy Magnesium Hydroxide Powder manufactured by Tomita Pharmaceutical Co., Ltd. with the same raw material and the same blending ratio as those used in Example 13 were weighed. Suspended in 5 L. Next, the obtained aqueous suspension was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 300 mm), and the cake on the filter paper was washed four times with 5 L of water (20 L in total). 100 mL of the 4th cleaning solution was sampled, 5 mL of an 8 mol / L potassium hydroxide aqueous solution was added, and then an NN indicator was added. As a result, the cleaning solution turned blue. From this, it was confirmed that the calcium ion elution cleaning was completed.

The entire cake on the filter paper was washed with water and suspended to obtain a 2680 g suspension. The solid content ratio was 11.08% as the magnesium content. Further, the calcium impurity and sulfate impurity contents were measured, and the calcium and sulfate contained in the suspension were converted to the ratio per magnesium (as Mg). As a result, Ca was 1400 ppm and SO ₄ was 3600 ppm.

Put 490g of this suspension evenly into a 1L container with a polypropylene lid, take 5 pieces, add a predetermined amount of sodium hydroxide to each, adjust the liquid volume to 500mL, and seal 90 ° C It put into the thermostat. The treatment was performed for a total of 4 hours while degassing and degassing every 30 minutes.

After the treatment, each liquid was cooled and then suction filtered with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 150 mm), and the cake on the filter paper was washed 4 times with 1 L of water (4 L in total). When 20 mL of the 4th washing solution was put into a Nessler tube, 1 mL of 10% hydrochloric acid was added, and then 2 mL of an aqueous solution of barium chloride dihydrate (an aqueous solution in which 250 g of barium chloride dihydrate was dissolved in water) was added. No cloudiness was observed. This confirmed that elution removal of sulfate ions was completed. The cake on the filter paper was collected, resuspended in water, and the water-purified suspension of the insoluble magnesium compound was completely dissolved in hydrochloric acid, and then 20 mL of the solution was syringe filtered (Millipore Mirex PES, pore size 0.45 μm). This was used as a sample solution. The impurity content of Ca and SO _{4 in} each sample solution was determined as a ratio to magnesium (as Mg) dissolved in the sample solution. The results are shown in Table 6.

Example 20
550 g of USP heavy magnesium oxide powder manufactured by Tomita Pharmaceutical Co., Ltd. was weighed and suspended in 5 L of water. Next, the suspension was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 300 mm), and the cake on the filter paper was washed 4 times with 5 L of water (20 L in total). 100 mL of the 4th cleaning solution was sampled, 5 mL of an 8 mol / L potassium hydroxide aqueous solution was added, and then an NN indicator was added. As a result, the cleaning solution was blue. From this, it was confirmed that the calcium ion elution cleaning was completed. The entire cake on the filter paper was washed with water and suspended to obtain a suspension with a feed amount of 2600 g.

10 g of sodium hydroxide was added to the suspension to make the total volume 2.5 L (NaOH concentration: 0.1 mol / L, pH 13), and the mixture was sealed with a cover and kept at 90 ± 2 ° C. while stirring while suppressing evaporation.

The treated liquid was subjected to suction filtration with a Buchner funnel (filter paper No. 131, manufactured by Advantech, diameter 300 mm), and the cake on the filter paper was washed four times with 5 L of water (20 L in total). When 20 mL of the 4th washing solution was put into a Nessler tube, 1 mL of 10% hydrochloric acid was added, and then 2 mL of an aqueous solution of barium chloride dihydrate (an aqueous solution in which 250 g of barium chloride dihydrate was dissolved in water) was added. No cloudiness was observed. From this, it was confirmed that elution removal of sulfate ions was completed. The cake on the filter paper was dispersed while being washed away with water and recovered as a suspension to obtain 3120 g of a suspension sample (the solid content ratio was 9.890% as the magnesium content).

The recovered suspension was divided into 2 minutes, of which 1545 g was collected separately (used in Example 21). The remaining 1545 g (solid content ratio: 152.8 g as magnesium content; 6.285 mol) was transferred to a 3 L enamel container, covered with a polypropylene sheet cover, and the upper surface of the container was stirred with 1064 g of synthetic hydrochloric acid (produced by Toa Gosei Co., Ltd.) 35.70% as HCl, HCl; 379.9 g) and weighed slowly over 1 hour to obtain 2570 g of a reaction suspension.

For smooth filtration, before adding hydrochloric acid, 45 g of aluminum chloride solution (AX-10S, manufactured by Asada Chemical Industry Co., Ltd.) as a filter aid (flocculating agent) (4.5 g as Al ₂ O ₃ , HCl 9.7 g) was added to the suspension. The amount of hydrochloric acid used in this reaction was equivalent to n = 0.85.

After adding hydrochloric acid, the mixture was stirred for 3 hours. Next, after suction filtration (filter paper No. 131, manufactured by Advantech, diameter 150 mm) with a Buchner funnel, further using a precision filter paper (0.20 μm mixed cellulose ester, manufactured by Advantech, diameter 47 mm) with a Buchner funnel. Suction filtration was performed. After carrying out the two-stage filtration in this way, 2480 g of a filtrate sample (the solid content ratio was 5.13% as the magnesium content) was recovered. After collecting 60 g of this liquid as a sample for purity comparison before crystallization, 2420 g of the remaining liquid was heated and concentrated in a 3 L enamel container, boiled until the liquid volume reached 1262 g, and then naturally cooled with stirring in a covered state. After maintaining the temperature at 60 ° C. for 1 hour, it was cooled to 30 ° C. over 2 hours while controlling the temperature to precipitate crystals.

The crystal-containing liquid is suction filter paper no. 2, manufactured by Advantech Co., Ltd., diameter 150 mm), and 320 g of filtration residue was collected and used as an analysis sample. The magnesium content of the sample crystals and the sample for purity comparison before crystallization, and the ratio of the content of impurities (calcium, sulfate, iron, Al) to the magnesium content were measured. The results are shown in Table 7.

Example 21
1544 g of the suspension separately recovered in Example 20 (152.7 g as Mg; 6.281 mol) was transferred to a 3 L enamel container, and the upper surface of the container was covered with a polypropylene sheet, and 1257 g of synthetic hydrochloric acid (Toa Gosei Co., Ltd.) was stirred. Production content: 35.70% as HCl, 448.7 g) was weighed and added dropwise over 1 hour to obtain 2664 g of a reaction suspension. The amount of hydrochloric acid used in this reaction was equivalent to n = 0.98.

The filtrate was allowed to stand overnight, the supernatant clarified portion was extracted and collected, and suction filtration (filter paper 0.20 μm, mixed cellulose ester, manufactured by Advantech, diameter 47 mm) was performed using a Buchner funnel, and 2320 g of a filtrate sample ( The solid content ratio was 5.67% as magnesium content). After collecting 60 g of this liquid as a sample for purity comparison before crystallization, the remaining liquid 2260 g was heated and concentrated in a 3 L enamel container, boiled to 1306 g, and then naturally cooled with stirring in a covered state. After maintaining the temperature at 1 ° C. for 1 hour, it was cooled to 30 ° C. over 2 hours while controlling the temperature to precipitate crystals. The crystal-containing liquid was subjected to suction filtration with a Buchner funnel (filter paper No. 2, manufactured by Advantech, diameter 150 mm), and 340 g of the filtration residue was recovered and used as an analysis sample. The magnesium content of the sample crystals and the sample for purity comparison before crystallization, and the ratio of the content of impurities (calcium, sulfate, iron, Al) to the magnesium content were measured. The results are shown in Table 7.

Comparative Example 3
300 g of USP heavy magnesium oxide powder manufactured by Tomita Pharmaceutical Co., Ltd. was placed in a 3 L enamel container and suspended in water to make the total amount 1870 g (176.0 g as Mg; 7.240 mol). The upper surface of the container was covered with a polypropylene sheet, and while stirring, 1483 g of synthetic hydrochloric acid (manufactured by Toa Gosei Co., Ltd., 35.70%, 529.4 g, 14.52 mol as HCl content) was added and dissolved over 1 hour. In addition, the usage-amount of hydrochloric acid used for this reaction was equivalent to n = 1.0.

The solution was allowed to stand overnight, and the supernatant clarified portion was extracted and collected, and after stirring, suction filtered with a Buchner funnel (filter paper 0.20 μm, mixed cellulose ester, Advantech, diameter 47 mm), and 2370 g of a filtrate sample ( The solid content ratio was 5.60% as magnesium content). After collecting 60 g of this liquid as a sample for purity comparison before crystallization, the remaining liquid 2310 g was heated and concentrated in a 4.5 L enamel container, boiled up to 1318 g, and then naturally cooled with stirring in a covered state. After maintaining the temperature at 60 ° C. for 1 hour, it was cooled to 30 ° C. over 2 hours while controlling the temperature to precipitate crystals. The crystal-containing liquid was subjected to suction filtration with a Buchner funnel (filter paper No. 2, manufactured by Advantech, diameter 150 mm), and 370 g of filtration residue was recovered and used as an analysis sample. The magnesium content of the sample crystals and the sample for purity comparison before crystallization, and the ratio of the content of impurities (calcium, sulfate, iron, Al) to the magnesium content were measured. The results are shown in Table 7.

As is clear from the results in Table 7, in Comparative Example 3 treated with n = 1.0, a large amount of impurities remaining in the raw material remained in the recrystallized product, whereas in the present invention, It can be seen that the recrystallized product produced by the production method can remove impurities effectively, resulting in high purity magnesium chloride crystals.

Claims

A method for producing an aqueous magnesium chloride solution, comprising:
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 nmol per 1 mol of Mg 2+ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) A method for producing a magnesium chloride aqueous solution, comprising a separation step of obtaining a magnesium chloride aqueous solution by removing sludge containing an insoluble magnesium compound present in the reaction system.
The ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) contained in the magnesium chloride aqueous solution is 10 ppm or less, and the ratio of aluminum weight (weight as Al) is 100 ppm or less. Item 2. The manufacturing method according to Item 1.
The manufacturing method according to claim 1, wherein n is 0.50 ≦ n ≦ 0.98.
The production method according to claim 1, wherein the magnesium content (content as Mg) contained in the insoluble magnesium compound-based raw material is 24 to 60% by weight (in terms of dry matter).
The insoluble magnesium compound-based raw material has a ratio of iron weight (weight as Fe) of 160 ppm or more with respect to magnesium weight (weight as Mg) contained in the raw material, and a ratio of aluminum weight (weight as Al) The production method according to claim 1, wherein is 160 ppm or more.
The content of calcium weight (as Ca) is 2000 ppm by weight or less and the content of sulfate weight (as SO 4 ) is 2000 with respect to the weight of magnesium (weight as Mg) contained in the insoluble magnesium compound-based raw material. The manufacturing method of Claim 5 which is weight ppm or less.
The manufacturing method of Claim 1 whose density | concentration of magnesium chloride aqueous solution is 10 weight% or more.
Prior to the reaction step, the production method according to claim 1, further comprising a washing step including a water washing treatment of the insoluble magnesium compound-based raw material.
The cleaning process
(A) a first step including a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation;
(B) An aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step is prepared, and alkali is added and mixed until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. The manufacturing method of Claim 8 including the 2nd process including the process of wash | cleaning the obtained solid content with water.
The insoluble magnesium compound-based raw material after the washing step has a calcium weight (weight as Ca) ratio of 2000 ppm or less with respect to the magnesium weight (weight as Mg) contained in the raw material, and the sulfate weight ( The production method according to claim 8 or 9, wherein a ratio of (weight as SO 4 ) is 2000 ppm or less.
The insoluble magnesium compound-based raw material before passing through the washing step has a ratio of iron weight (weight as Fe) of 160 ppm or more, aluminum weight (weight as Al) to magnesium weight (weight as Mg) contained in the raw material. The ratio of weight) is 160 ppm or more, the ratio of calcium weight (weight as Ca) is 3000 ppm or more, and the ratio of sulfate weight (weight as SO 4 ) is 10,000 ppm or more. Production method.
The production method according to claim 1, further comprising a step of adding aluminum chloride in the liquid phase in the reaction step.
A method for producing high-purity magnesium chloride,
(1) When reacting an insoluble magnesium compound-based raw material with hydrogen chloride, 2 nmol per 1 mol of Mg 2+ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98). A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(2) a separation step of obtaining an aqueous magnesium chloride solution by removing sludge containing insoluble magnesium compounds present in the reaction system;
(3) A method for producing high-purity magnesium chloride, comprising a recrystallization step of recrystallizing magnesium chloride from the aqueous solution.
The manufacturing method of Claim 13 which concentrates and recrystallizes magnesium chloride aqueous solution in a recrystallization process.
The ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) contained in the magnesium chloride aqueous solution is 10 ppm or less, and the ratio of aluminum weight (weight as Al) is 100 ppm or less. Item 14. The manufacturing method according to Item 13.
The manufacturing method of Claim 13 whose said n is 0.50 <= n <= 0.98.
The production method according to claim 13, wherein the magnesium content (content as Mg) contained in the insoluble magnesium compound-based raw material is 24 to 60% by weight (in terms of dry matter).
The insoluble magnesium compound-based raw material has a ratio of iron weight (weight as Fe) of 160 ppm or more with respect to magnesium weight (weight as Mg) contained in the raw material, and a ratio of aluminum weight (weight as Al) The production method according to claim 13, wherein is not less than 160 ppm.
The content of calcium weight (as Ca) is 2000 ppm by weight or less and the content of sulfate weight (as SO 4 ) is 2000 with respect to the weight of magnesium (weight as Mg) contained in the insoluble magnesium compound-based raw material. The manufacturing method of Claim 18 which is weight ppm or less.
The manufacturing method of Claim 13 whose density | concentration of magnesium chloride aqueous solution is 10 weight% or more.
The production method according to claim 13, further comprising a washing step including a water washing treatment of the insoluble magnesium compound-based raw material prior to the reaction step.
The cleaning process
(A) a first step including a step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material and subjecting the aqueous suspension to solid-liquid separation;
(B) An aqueous suspension of the insoluble magnesium compound-based raw material that has undergone the first step is prepared, and alkali is added and mixed until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. The manufacturing method of Claim 21 including the 2nd process including the process of wash | cleaning the obtained solid content with water.
The insoluble magnesium compound-based raw material after the washing step has a calcium weight (weight as Ca) ratio of 2000 ppm or less with respect to the magnesium weight (weight as Mg) contained in the raw material, and the sulfate weight ( The production method according to claim 21 or 22, wherein a ratio of (weight as SO 4 ) is 2000 ppm or less.
The insoluble magnesium compound-based raw material before the washing step has a ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) contained in the raw material is 160 ppm or more, and aluminum weight (Al The ratio of the weight (as weight) is 160 ppm or more, the ratio of calcium weight (weight as Ca) is 3000 ppm or more, and the ratio of sulfate weight (weight as SO 4 ) is 10,000 ppm or more, 22. The production method according to 22.
The production method according to claim 13, further comprising a step of adding aluminum chloride in the liquid phase in the reaction step.
A method for producing high-purity magnesium chloride,
(A) The magnesium content (content as Mg) is 24 to 60% by weight (in terms of dry matter), and the ratio of iron weight (weight as Fe) to magnesium weight (weight as Mg) is 160 ppm. The ratio of aluminum weight (weight as Al) is 160 ppm or more, the ratio of calcium weight (weight as Ca) is 3000 ppm or more, and the ratio of sulfate weight (weight as SO 4 ) is 10,000 ppm. A water washing step including a step of preparing an aqueous suspension of the insoluble magnesium compound-based raw material as described above and subjecting the aqueous suspension to solid-liquid separation,
(B) A step of preparing an aqueous suspension of an insoluble magnesium compound-based raw material that has undergone a water washing step, adding and mixing alkali until the aqueous suspension has a pH of 12 to 14, followed by heating and solid-liquid separation. Alkaline washing step (C) The ratio of calcium weight (weight as Ca) is 2000 ppm or less and the ratio of sulfate weight (weight as SO 4 ) is 2000 ppm or less with respect to magnesium weight (weight as Mg). When reacting an insoluble magnesium compound-based raw material that has undergone an alkali cleaning step with hydrogen chloride, 2 nmol per mol of Mg 2+ ions contained in the raw material (where n satisfies 0.00 <n ≦ 0.98) A reaction step of obtaining a reaction product by reacting hydrogen chloride of
(D) By removing sludge containing an insoluble magnesium compound present in the reaction system, the ratio of iron weight (weight as Mg) to magnesium weight (weight as Mg) is 10 ppm or less, and aluminum weight ( A separation step of obtaining a magnesium chloride aqueous solution having a ratio of (weight as Al) of 100 ppm or less,
(E) A method for producing high-purity magnesium chloride, comprising a step of recrystallizing magnesium chloride from the aqueous solution.