JP4746853B2 - High purity metal hydroxide, purification method and production method thereof, hydroxide and oxide obtained by these methods, and synthetic resin composition and synthetic resin molded article - Google Patents

Description

  The present invention relates to high-purity metal hydroxides, purification methods and production methods thereof, hydroxides and oxides obtained by these methods, and synthetic resin compositions and synthetic resin molded articles.

In general, metals in metal salt waste liquids are often separated in the form of hydroxides by adding alkali, but the sludge produced in this separation process contains polyvalent anions as impurities, so it can be recycled. Is currently not suitable for landfill disposal.
And, as a method of recovering useful metals from the metal salt waste liquid, metal adsorption by an ion exchange membrane or an ion exchange resin has been proposed (see Patent Document 1). In these methods, ion exchange that adsorbs metal ions is proposed. Resins and ion exchange membranes must be eluted and regenerated with acid, and a large amount of excess acid is mixed in the eluent, so that the metal is hardly reused. In addition, the recovery of metals using ion exchange resins or ion exchange membranes can be used only for some expensive metals because the price of ion exchange resins and ion exchange membranes is higher than the metal adsorption capacity that can be recovered.

In addition, alkaline earth metal waste liquids discharged during flue gas desulfurization at power plants, etc., have been studied as raw materials for gypsum as in-process recycling using magnesium hydroxide and ammonia. Is liberated and volatilizes, and there is concern about the diffusion of ammonia to the external environment. In order to prevent this, the cost of process equipment is also high.
JP 7-54200 A

  The present invention has been made in view of the background as described above, and an object of the present invention is to economically recover metals in metal salt waste liquids such as plating waste liquid and desulfurization waste liquid as high-purity and fine-particle hydroxides. High purity metal hydroxides that can be used as plating raw materials, plastic fillers, metallurgical metallurgy, ceramic raw materials, purification methods and manufacturing methods thereof, hydroxides and oxides obtained by these methods, Another object is to provide a synthetic resin composition and a synthetic resin molded article.

In order to solve the above-described problems, the present invention proposes a method for purifying a metal hydroxide using the difference in solubility of metal salts in water.
That is, the present invention is (1) the solubility of hydroxide in water at 0 ° C. to 100 ° C. is 0.1 g or less and the solubility of sulfate in water at 0 ° C. to 90 ° C. is 5.0 g or more. A metal hydroxide to be purified containing at least sulfate ions as impurities, and a metal having a solubility in water at 0 ° C. to 100 ° C. of water of 0.1 g or less, and 0 ° C. to 100 ° C. A first metal salt having a solubility in water of 1.0 g or more in
The metal hydroxide to be purified and the metal salt are suspended in water, and the suspension has a concentration of 5 to 500 parts by mass of metal hydroxide and 1.0 part by mass or more of metal salt with respect to 100 parts by mass of water. A step of making a turbid liquid,
(2) The suspension obtained in (1) is heated in the range of 90 ° C. to 250 ° C., and a divalent or higher anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 0 A step of precipitating as a metal sulfate having a solubility in water of 0.1 g or less at 100 ° C. to 100 ° C. and other salts of divalent or higher anions,
(3) Classifying the solids in the suspension heated in (2) , or classifying the solid powder obtained after drying the suspension, and fine particles having a particle size of 44 μm or less And a step of separating the coarse particles larger than 44 μm. (Claim 1)

The metal hydroxide purification method of the present invention is as follows: (1) The solubility of the hydroxide in water at 0 ° C to 100 ° C is 0.1 g or less and the sulfate is in the range of 0 ° C to 90 ° C. A metal hydroxide to be purified, comprising at least sulfate ions as impurities, and a solubility in water at 100 ° C. of water of not more than 5.0 g, and a solubility in water at 100 ° C. of not more than 5.0 g. The solubility of water in the temperature range of 0 ° C. to 90 ° C. reaches a maximum value or has a negative correlation with the temperature, and the maximum solubility in water at 0 to 90 ° C. is 0.1 g or more. And a second metal salt having a solubility in water at 0 ° C. to 100 ° C. of 5.0 g or more.
The metal hydroxide to be purified and the metal salt are suspended in water, and the suspension has a concentration of 5 to 500 parts by mass of metal hydroxide and 1.0 part by mass or more of metal salt with respect to 100 parts by mass of water. A step of making a turbid liquid,
(2) The suspension obtained in (1) is heated in the range of 90 ° C. to 250 ° C., and a divalent or higher-valent anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 100 A step of precipitating as a metal sulfate having a solubility at 5.0 ° C. of 5.0 g or less and other salts of divalent or higher anions,
(3) After filtering the suspension heated in (2), the solid is washed with water at 50 ° C. or lower, and divalent or higher anions containing sulfate ions present as impurities are dissolved in water and removed. And a step of performing (Claim 2).

The method for purifying a metal hydroxide according to the present invention further comprises: (1) the solubility of the hydroxide in water at 0 ° C. to 100 ° C. is 0.1 g or less and the sulfate is in the range of 0 ° C. to 90 ° C. A metal hydroxide to be purified, comprising at least sulfate ions as impurities, and a solubility in water at 100 ° C. of water of not more than 5.0 g, and a solubility in water at 100 ° C. of not more than 5.0 g. The solubility of water in the temperature range of 0 ° C. to 90 ° C. reaches a maximum value or has a negative correlation with the temperature, and the maximum solubility in water at 0 to 90 ° C. is 0.1 g or more. And a second metal salt having a solubility in water at 0 ° C. to 100 ° C. of 5.0 g or more.
The metal hydroxide to be purified and the metal salt are suspended in water, and the suspension has a concentration of 5 to 500 parts by mass of metal hydroxide and 1.0 part by mass or more of metal salt with respect to 100 parts by mass of water. A step of making a turbid liquid,
(2) The suspension prepared in (1) is heated in a range of 90 ° C. to 250 ° C., and a divalent or higher anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 100 A step of precipitating as a metal sulfate having a solubility at 5.0 ° C. of 5.0 g or less and other salts of divalent or higher anions,
(3) Classifying the solids in the suspension heated in (2), or classifying the solid powder obtained after drying the suspension, and fine particles having a particle size of 44 μm or less And coarse particles larger than 44 μm are separated, and the classified fine particles are washed with water at 50 ° C. or lower, and divalent or higher anions containing sulfate ions present as impurities are dissolved in water. And removing it. (Claim 3).

  The present application further purifies the transition metal hydroxide produced by reacting alkali metal or ammonia with the transition metal sulfate waste liquid discharged from the plating process or the metal etching treatment process by the above-described metal hydroxide purification method. The present invention relates to a method for producing a metal hydroxide recovered as a transition metal hydroxide.

  The present application further relates to an alkali earth metal hydroxide produced by reacting an alkali metal or ammonia with an alkaline earth metal sulfate waste liquid discharged in a flue gas desulfurization process after burning coal or heavy oil. The present invention relates to a method for producing a metal oxide, which is purified by a hydroxide purification method and recovered as a high-purity alkaline earth metal hydroxide.

According to the present invention, (i) the sulfur content is 0.5 mass% or less as an impurity, (ii) 90 vol% or more is 20 μm or less in the volume particle size distribution by the laser diffraction scattering method, and (iii) B.I. E. T.A. Nickel hydroxide having a specific surface area of 20 m ² / g or less and calcined nickel oxide , (i) a sulfur content of 0.5% by mass or less as an impurity, (ii) 90 vol in volume particle size distribution by laser diffraction scattering method % Or more is 20 μm or less, and (iii) B. E. T.A. Cobalt hydroxide having a specific surface area of 20 m ² / g or less and calcined cobalt oxide , (i) a sulfur content of 0.5% by mass or less as an impurity, (ii) 90 vol in volume particle size distribution by laser diffraction scattering method % Or more is 20 μm or less, and (iii) B. E. T.A. Copper hydroxide having a specific surface area of 20 m ² / g or less and calcined copper oxide , (i) a sulfur content of 0.5% by mass or less as an impurity, (ii) 90 vol in volume particle size distribution by laser diffraction scattering method % Or more is 20 μm or less, and (iii) B. E. T.A. Magnesium hydroxide having a specific surface area of 20 m ² / g or less and calcined magnesium oxide , (i) a sulfur content of 0.5% by mass or less as an impurity, and (ii) 90 vol in volume particle size distribution by laser diffraction scattering method % Or more is 20 μm or less, and (iii) B. E. T.A. Zinc hydroxide having a specific surface area of 20 m ² / g or less and calcined zinc oxide , (i) a sulfur content of 0.5% by mass or less as an impurity, and (ii) 90 vol in volume particle size distribution by laser diffraction scattering method % Or more is 20 μm or less, and (iii) B. E. T.A. Aluminum hydroxide having a specific surface area of 20 m ² / g or less and calcined aluminum oxide can be obtained by the method.

Furthermore, in the method of claim 1 or claim 3, the solubility of sulfate in water at 0 to 100 ° C. is 0.1 g or less in the coarse particles classified in (4) and (3). A step of adding a third metal salt made of metal and having a solubility in water at 0 ° C. to 100 ° C. of not less than 1.0 g and recovering as a monovalent metal salt aqueous solution added in the step. Desirable ( Claim 6 ).
Alternatively, in the method of claim 1 or claim 3, (4) at least the coarse particles classified in (3) and the liquid in the suspension of (3) are suspended, And a hydrothermal treatment to separate the solid content and the liquid content and recovering the solution as a monovalent metal salt aqueous solution added in the process. Addition of a second metal salt consisting of a metal having a solubility in water of 0 to 100 ° C. of water of 0.1 g or less, and a solubility in water of 0 to 100 ° C. of 1.0 g or more. Then, it is desirable to cool to 50 ° C. or lower and recover the monovalent metal salt aqueous solution added during the process ( claim 7 ).

  Metals in metal salt waste liquids such as plating waste liquid and desulfurization waste liquid can be recovered economically as high-purity and fine-particle hydroxides, and can be used as plating raw materials, plastic fillers, metallurgical metallurgy, ceramic raw materials, etc. It is possible to economically purify and produce metal hydroxides that are pure and fine. Moreover, the magnesium hydroxide produced | generated by this method can be used suitably as a composition component for the synthetic resin moldings which have heat-resistant deterioration property and a flame retardance.

Embodiments of the present invention will be described below.
As a result of intensive studies in view of the aforementioned problems, the present inventors have created the present invention based on the following knowledge.

Metals such as cobalt, copper, zinc, nickel, aluminum, and magnesium that are used in large quantities in processes such as metal plating and flue gas desulfurization are not used in plating wastewater or desulfurization, even though their sulfates are soluble in water. When recovered from the waste liquid as an alkali hydroxide, it is difficult to remove by ordinary water washing or the like containing divalent or higher anions mainly composed of sulfate ions present in the waste liquid as impurities.
However, it should be purified in an aqueous solution of a salt of calcium, strontium, barium, radium, scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, ytterbium and a monovalent anion that is soluble in water. By suspending a metal hydroxide such as cobalt, copper, zinc, nickel, aluminum, magnesium, etc., and heating it, divalent or more anions that are impurities in the metal hydroxide are converted into calcium, strontium, barium, Coarse-grained fractions that are sparingly soluble simple salts of radium, scandium, yttrium, lanthanum and sulfate ions, or sparingly soluble double salts of sulfate ions and other anions having a valence of 2 or more, and that can be classified by wind and sieving. As a result, it was found to be precipitated.

  In particular, when the metal hydroxide is suspended in an aqueous solution of a salt of calcium, yttrium, lanthanum, cerium, praseodymium, neodymium, ytterbium and a monovalent anion, the heated metal hydroxide is dehydrated into cold water. It has been found that, by washing, it is efficiently removed as a sparingly soluble simple salt with sulfate ion or a sparingly soluble double salt with sulfate ion and other divalent or higher anions. More specifically, calcium, yttrium, lanthanum, cerium, praseodymium, neodymium, ytterbium sulfate has a maximum solubility in water at a low temperature region of 50 ° C. or lower, and calcium, yttrium, lanthanum, cerium, praseodymium, Each of the neodymium and ytterbium sulfates has a solubility at 0 ° C. of 1.5 times or more of the solubility at 90 ° C. Accordingly, during heating, an anion having a valence of 2 or more, which is an impurity of the metal hydroxide, is precipitated as a metal salt, and the deposited metal salt is easily dissolved in cold water.

Further, the separated aggregate or filtrate is insoluble as a metal sulfate salt in calcium, strontium, yttrium, lanthanum, cerium, praseodymium, neodymium, and ytterbium precipitated as sulfates in the aggregate or filtrate (solubility). 0.1g or less) Add a salt of lead ion, barium ion or radium ion and monovalent inorganic anion, add water as necessary, stir, cool to 50 ° C or less, calcium, strontium , Yttrium, lanthanum, cerium, praseodymium, neodymium, ytterbium and monovalent inorganic salt solutions and sulfate salts of lead ions, barium ions or radium ions that are insoluble as metal sulfate salts (solubility at 50 ° C. is 0.1 g or less) Separated as calcium, strontium, yttrium Found lanthanum, cerium, praseodymium, neodymium, a process for recovering ytterbium in step.
Further, the separated agglomerate or filtrate is made of a metal having a solubility in water of 0 to 100 ° C. as a sulfate in a metal sulfate precipitated in the agglomerate or filtrate. A metal salt (third metal salt) having a solubility in water at 0 ° C. to 100 ° C. of 1.0 g or more was added, water was added as needed, and the mixture was stirred and cooled to 50 ° C. or less. It was also found that it can be recovered as a monovalent metal salt aqueous solution added during the process by precipitation and separation as a metal sulfate.

Next, a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a process diagram of a method for producing a flame retardant according to an embodiment of the present invention. The present invention is basically a metal sulfate having a certain degree of solubility in water and can be applied if it is not decomposed during hydrothermal treatment.
For example, as shown in FIG. 1, the method for producing a flame retardant according to the present embodiment uses the sulfuric acid band waste liquid (aluminum sulfate waste liquid) discharged in the aluminum surface treatment step 11 as a starting material, and the flame retardant mainly from aluminum sulfate. A production separation process for producing and separating aluminum hydroxide, a purification process for purifying the obtained aluminum hydroxide, and a remaining substance other than aluminum hydroxide to be a flame retardant, a substance for the production process and other useful substances And a post-processing step.

<Production separation process>
In the production separation step, sodium hydroxide is reacted with the aluminum sulfate waste liquid.
At this time, aluminum hydroxide particles are generated as in the following reaction formula.
Al ₂ (SO ₄ ) ₃ + 6NaOH → 2Al (OH) ₃ ↓ + 3Na ₂ SO ₄
The sulfate ions are partially incorporated in the aluminum hydroxide crystal and remain as impurities.

  In this reaction, even if sodium hydroxide is added to an equivalent amount or more and reacted in an environment with a high pH, the sulfate ions that have entered aluminum hydroxide are not reacted with a product that has reacted with a monovalent acid such as aluminum chloride. Unlikely, it adheres to the agglomeration surface of primary particles in crystal lattice defects or secondary particles and is difficult to remove. This is because polyvalent anions such as sulfate ions and phosphate ions are more difficult to remove from the metal ions in the crystal than monovalent anions such as chloride ions and nitrate ions. .

  Aluminum sulfate itself is a salt that is soluble in water. However, when incorporated in the crystal of aluminum hydroxide, it can be removed to some extent by washing with water, but sulfate ions do not decrease below a certain concentration. Further, since sulfate ions inhibit the crystallization of aluminum hydroxide, crystals of aluminum hydroxide with a high degree of crystallization cannot be obtained.

  Therefore, aluminum hydroxide containing sulfate ions is separated by a dehydration and washing process and purified by a purification process. In addition, other reaction waste liquid is returned to sodium hydroxide while producing useful gypsum by a post-treatment process.

<Purification process>
As shown on the right side of FIG. 1, a supersaturated aqueous solution of cerium nitrate is used as a mother liquor for purification, and this is reacted with aluminum hydroxide separated in the production separation step.
Aluminum hydroxide is a “metal hydroxide” to be purified as defined in the claims, and here, it is a suspension suspended in water at a concentration of 5 to 500 g with respect to 100 g of water. .
The reason why the mass of aluminum hydroxide is set to 5 g or more with respect to 100 g of water is to improve the efficiency of the treatment, and the reason why it is set to 500 g or less is to appropriately perform the purification operation including the suspension treatment.
Cerium nitrate is the “first metal salt” in the claims, and here, a solution having a concentration of 1.0 g or more with respect to 100 g of water is prepared. The reason why the concentration is 1.0 g or more with respect to 100 g of water is that cerium nitrate, which is a metal salt, sufficiently supplies cerium ions for separating sulfate ions.
As the first metal salt, lead acetate, lead chloride, lead nitrate, lead perchlorate, barium chloride, barium bromide, barium iodide, barium perchlorate, barium formate, barium lactate, barium nitrate, thiocyanate Barium acid, barium acetate, barium cyanide, radium chloride, radium bromide, radium iodide, radium perchlorate, radium formate, radium lactate, radium nitrate, radium thiocyanate, radium acetate, radium cyanide and the like. Two or more of these metal salts may be used in duplicate.

  And the suspension which mixed these is heated at 90-250 degreeC. The reason why the temperature is 90 ° C. or higher is to reduce the solubility of cerium sulfate and promote the removal of sulfate ions from the metal hydroxide. The reason why the temperature is 250 ° C. or lower is for safe treatment.

The reaction at this time will be described.
First, cerium sulfate is a poorly soluble salt in water, and its solubility decreases at high temperatures. In addition, cerium sulfate has a high solubility with respect to a cerium nitrate solution and can form an aqueous solution having a high concentration.
Therefore, when aluminum hydroxide containing sulfate ion as an impurity is suspended in normal water, the sulfate ion dissolved in water and the sulfate ion remaining in the aluminum hydroxide crystal are in phase equilibrium. The migration of sulfate ions from water crystals to water stops. However, when aluminum hydroxide is suspended in a cerium nitrate solution and heated, the sulfate ions in the solution combine with calcium ions to form poorly soluble calcium sulfate, reducing the concentration of sulfate ions in the water, and thus phase equilibrium. Therefore, it is considered that sulfate ions in the aluminum hydroxide crystal migrate into water.

And since the sulfate ion which inhibits crystallization reduces from aluminum hydroxide, the crystal | crystallization of aluminum hydroxide grows and the defective part of a crystal lattice reduces. The sulfate ion, phosphate ion, and silicate ion that existed in aluminum hydroxide are unevenly distributed as anions in the lattice defects of the crystal due to the polarity. It is considered that the lattice defects in which ions, phosphate ions, and silicate ions are unevenly distributed are reduced, and the amount of sulfate ions, phosphate ions, and silicate ions taken into the aluminum hydroxide crystal is small even after hydrothermal treatment.
As a result, since sulfate ions in the crude aluminum hydroxide are fixed in lattice defects in the aluminum hydroxide crystal, they cannot be dissolved and separated even by washing with ordinary cold water. By heating in an aqueous solution of a salt containing a cation that becomes sparingly soluble (in this case, it has some solubility as a sulfate in the low temperature region), it is coarse and hardly soluble sulfate (in this case, in the low temperature region). And a mixture of aluminum hydroxide particles that are fine and do not contain sulfate ions in lattice defects.
However, this description does not necessarily describe all reaction processes related to this reaction.

In this way, impurities of polyvalent ions such as sulfate ions are precipitated from aluminum hydroxide as coarse particles such as calcium sulfate larger than 44 μm and can be removed.
Therefore, this is classified by filtration to separate coarse particles (CeNO ₃ and Ce ₂ (SO ₄ ) ₃ ) of impurities larger than 44 μm and fine particles (Al (OH) ₃ ) of 44 μm or less.

  Here, by classifying the coarse particles larger than 44 μm and the fine particles less than 44 μm, the coarse particles containing a large amount of sulfate ions and the fine particles containing little sulfate ions are separated, and the fine particles Although the aluminum hydroxide was purified, the sulfate ions may be separated by utilizing the dissolution of sulfate ions without depending on the classification. That is, the sulfate ions can be removed by dissolving the sulfate ions by washing the precipitated solid content with water of 50 ° C. or less. Alternatively, after the fine particles are classified and obtained, the fine particles are washed with water of 50 ° C. or less, so that the sulfate ions as impurities can be dissolved and further reduced.

  In this case, instead of the first metal salt described above, the solubility of the sulfate in water at 100 ° C. is 5.0 g or less, and the sulfate is in water in the temperature range of 0 ° C. to 90 ° C. The solubility is a maximum value, or the solubility is negatively correlated with the temperature and the maximum solubility in water at 0 to 90 ° C. is 0.1 g or more. The second metal salt having a solubility in water of 5.0 g or more is preferably selected and subjected to suspension and hydrothermal treatment.

  Examples of the second metal salt at this time include yttrium acetate, yttrium chloride, yttrium nitrate, yttrium acetate, yttrium bromide, yttrium iodide, yttrium perchlorate, yttrium formate, yttrium lactate, calcium acetate, calcium chloride, Calcium nitrate, calcium acetate, calcium bromide, calcium iodide, calcium perchlorate, calcium formate, calcium lactate, strontium acetate, strontium chloride, strontium nitrate, strontium acetate, strontium bromide, strontium iodide, strontium perchlorate, Strontium formate, strontium lactate, lanthanum acetate, lanthanum chloride, lanthanum nitrate, lanthanum acetate, lanthanum bromide, lanthanum iodide, lanthanum perchlorate, lanthanum formate, lactic acid Lanthanum, cerium acetate, cerium chloride, cerium nitrate, cerium acetate, cerium bromide, cerium iodide, cerium formate, cerium lactate, praseodymium acetate, praseodymium chloride, praseodymium nitrate, praseodymium acetate, praseodymium bromide, praseodymium iodide, praseodymium formate , Praseodymium lactate, neodymium acetate, neodymium chloride, neodymium nitrate, neodymium acetate, neodymium bromide, neodymium iodide, neodymium perchlorate, neodymium formate, neodymium lactate, neodymium acetate, ytterbium acetate, ytterbium chloride, ytterbium nitrate, ytterbium acetate, Ytterbium bromide, ytterbium iodide, ytterbium formate, ytterbium lactate, uranium acetate, uranium chloride, uranium nitrate, uranium acetate, uranium bromide, uranium iodide, uranium formate, milk Yttrium uranium thiocyanate, yttrium salicylate, yttrium benzoate, yttrium gluconate, calcium thiocyanate, calcium salicylate, calcium benzoate, calcium gluconate, strontium thiocyanate, strontium salicylate, strontium benzoate, strontium gluconate, thiocyanate Lanthanum acid, lanthanum salicylate, lanthanum benzoate, lanthanum gluconate, cerium thiocyanate, cerium salicylate, cerium benzoate, cerium gluconate, praseodymium thiocyanate, praseodymium salicylate, praseodymium benzoate, praseodymium thiocyanate gluconate, Neodymium salicylate, neodymium benzoate, neodymium gluconate, ytterbium thiocyanate, Ytterbium, ytterbium benzoate, ytterbium gluconate, uranium thiocyanate, uranium salicylate, uranium benzoate, uranium gluconate, and the like can be used. Two or more of these metal salts may be used in duplicate.

Since solubility of cerium sulfate decreases at high temperatures (0.176 g at 0 ° C., 0.067 g at 100 ° C.), sulfate ions in cerium sulfate precipitated during hydrothermal heating must be dissolved and removed by washing with low-temperature soft water. I can do it. Since sulfate ions occupy most of the polyvalent anions, when separated as a cerium salt, it precipitates as a salt with other polyvalent ions mainly composed of sulfate ions.
Further, barium nitrate (third metal salt) is added to the solid content separated as a coarse particle, suspended in water, cooled to 0 ° C. after a predetermined time, and washed with ion-exchanged water. Ions and cerium ions can be separated. That is, the cerium content can be used again as a mother liquor.
As the third metal salt in this case, for example, lead nitrate, radium nitrate, barium chloride, or the like can be applied. Two or more of these metal salts may be used in duplicate.

The fine particles of aluminum hydroxide to be purified may be subjected to a surface treatment as needed. The agent for performing the surface treatment is not particularly limited as long as it does not impair the characteristics of the present invention. In general, fatty acids such as stearic acid and oleic acid, and metal salts of these fatty acids, stearins such as ptyl stearate, etc. Various known coupling agents such as acid esters, silane coupling agents, titanate coupling agents, aluminate coupling agents, copolymers of maleic acid / olefin, alkyl phosphate esters and metal salts thereof, and the like. A surface treatment agent is used.
And high purity aluminum hydroxide can be obtained by drying the aluminum hydroxide which passed through the surface treatment process. As will be described later, this aluminum hydroxide has fine particles and a uniform particle size, is excellent in dispersibility when mixed with a resin, and can be suitably used as a flame retardant.

<Post-processing process>
On the other hand, sodium sulfate separated as a coarse fraction in the production separation step is reacted with slaked lime (Ca (OH) ₂ ) to produce gypsum (CaSO ₄ .2H ₂ O) and sodium hydroxide (NaOH). Gypsum and sodium hydroxide are separated by dehydration and washing, and sodium hydroxide is reused in the production separation process, and gypsum is effectively utilized by itself.

As described above, high-purity aluminum hydroxide can be produced from the plating waste liquid, and gypsum can be obtained as a secondary agent.
However, the present invention is not limited to the embodiments described above, and can be implemented with appropriate modifications.

  First, in the purification process of the embodiment, aluminum hydroxide is taken as an example of the metal hydroxide to be purified, but is not limited thereto, and nickel hydroxide, cobalt hydroxide, hydroxide, which contains sulfate ions as impurities. The same applies to magnesium, zinc hydroxide and the like.

  And although cerium nitrate was used as a solute (metal salt) of the mother liquor for purification of the embodiment, it is not limited to this. From a metal whose solubility in water at 0 ° C. to 100 ° C. is 0.1 g or less. Any metal salt having a solubility in water at 0 ° C. to 100 ° C. of 1.0 g or more may be used. For example, calcium nitrate, lanthanum nitrate, or praseodymium nitrate may be used.

  In this embodiment, the present invention is applied to the waste liquid discharged from the plating equipment, but the present invention is not limited to this, and useful metals are extracted from the metal salt waste liquid discharged in the flue gas desulfurization process, the washing process, etc. It can also be applied to the case where it is economically purified and recovered. It can also be applied to obtain high-purity metal hydroxides by removing and purifying impurities in crude alkaline earth metal hydroxides and transition metal hydroxides, regardless of whether they are natural or artificial. Can do.

  Similarly, the metal hydroxide is purified by economically reducing divalent or higher anions mainly composed of sulfate ions, which are impurities of the metal hydroxide recovered from the sulfuric acid waste liquid. Economically removes impurities of divalent or higher anions that are difficult to remove due to the large Coulomb force against monovalent anions as impurities in metallurgical raw materials, metallurgical raw materials, and metal hydroxides for plastic fillers You can also. It is also possible to produce purified particulate metal hydroxides and calcined metal oxides useful for sintered metals, for recovered raw materials for plating, and for plastic fillers.

The metal hydroxide such as aluminum hydroxide obtained as described above can be used as a flame retardant material of a flame retardant resin, for example.
In this case, for example, aluminum hydroxide obtained by purifying according to the above embodiment on various resin materials such as ethylene-vinyl acetate polymer resin, polypropylene resin, polyethylene resin, vinyl chloride resin, polyester resin, urethane resin, etc. Is kneaded in an appropriate amount and molded into a desired form by hot press molding. Such a flame retardant resin can be suitably used as a coating resin for electric wires.

  Next, an example in which the present invention is applied to the purification of each metal hydroxide, an example in which the mother liquor used in the purification process is reused, an example in which the purified metal hydroxide is used as a flame retardant resin Is described below.

Example 1 [Nickel hydroxide]
Example 1 and Comparative Example 1 are examples in which impurity sulfate ions are fixed as coarse sulfates, separated and removed by classification based on particle size, and high-purity and fine-particle nickel hydroxide is generated.
(1) Nickel sulfate waste liquid (Ni 76.3 g / l, SO ₄ 127.7 g / l) and sodium hydroxide solution (sodium hydroxide JIS special grade manufactured by Kanto Chemical Co., Ltd. diluted to 4.06N in soft water) The mixture was kept at 25 ° C. and continuously reacted at a reaction rate of 98% (Na ⁺ / Ni ²⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate nickel hydroxide.
NiSO ₄ + 2NaOH → Ni (OH) ₂ ↓ + Na ₂ SO ₄
(2) The deposited nickel hydroxide was dehydrated with a Buchner funnel, and then washed with ion exchange water 5 times the nickel hydroxide.
(3) After suspending nickel hydroxide washed with ion-exchanged water in ion-exchanged water, calcium acetate monohydrate (special grade made by Kanto Chemical) was added to the suspension to make 100.0 g of ion-exchanged water. The concentration was adjusted to 5.9 g of nickel hydroxide and 5.1 g of calcium acetate anhydrous.
(4) Hydrothermal treatment was performed with stirring at 110 ° C. for 2 hours in an autoclave (OM Labtech High Pressure Microreactor MMJ).
(5) The hydrothermally treated nickel hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving net (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.
(6) The coarse stream and fine particles were individually dehydrated with a Buchner funnel, and washed with ion exchange water 5 times in terms of solids of each dehydrated product.

(mass)
After drying at 105 ° C. for 1 hour, the mass of each of the coarse particles and fine particles was measured and the ratio was calculated.
(Sulfur content)
Each sulfur content in the coarse and fine particles was measured with a sulfur analyzer (Model EMIA-120 manufactured by Horiba Seisakusho).
(Specific surface area)
Using an automatic specific surface area / pore distribution measuring device (BELSORP-mini, manufactured by Bell) E. T.A. Measured by the method.
(Particle size distribution)
The particle size distribution of fine particles was measured by a laser diffraction particle size distribution measuring device (Nikkiso Microtrac SPA7995). Moreover, the volume ratio of the part exceeding 20 micrometers among the measured fine particle part was calculated | required.

<< Comparative Example 1 >> [Nickel hydroxide]
In Example 1 (3), nickel hydroxide washed with ion-exchanged water without using calcium acetate monohydrate was suspended in ion-exchanged water, and nickel hydroxide was added to 100.0 g of ion-exchanged water. The same treatment and measurement as in Example 1 were performed except that the concentration was adjusted to 5.9 g.

Table 1 summarizes the measurement results of Example 1 and Comparative Example 1 described above.
As shown in Table 1, in Example 1, the separated coarse particles contained a large amount of sulfate ions (sulfur), and sulfate ions decreased in the fine particles. In addition, the sulfur content in nickel hydroxide before purification (state (2) of Example 1) was 0.99%.
Moreover, in Example 1, the particle diameter was equal in the range whose particle diameter is 20 micrometers or less.

Example 2 [Aluminum hydroxide]
In Example 2 and Comparative Example 2, impurity sulfate ions are fixed as coarse sulfate, and dissolved and removed with cold water using the increase in solubility of sulfate ions in a low temperature range. It is an Example which produces | generates aluminum oxide.
(1) Aluminum sulfate waste liquid (Al 32.8 g / l, SO ₄ 171.7 g / l) and sodium hydroxide solution (sodium hydroxide JIS special grade manufactured by Kanto Chemical Co., Ltd. diluted to 3.98N in soft water) The mixture was kept at 25 ° C. and continuously reacted at a reaction rate of 100% (Na ⁺ / Al ³⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate aluminum hydroxide.
Al ₂ (SO ₄ ) ₃ + 6NaOH → 2Al (OH) ₃ ↓ + 3Na ₂ SO ₄
(2) The precipitated aluminum hydroxide was dehydrated with a Buchner funnel and then washed with ion-exchanged water 5 times that of aluminum hydroxide.
(3) After suspending the aluminum hydroxide washed with ion-exchanged water in ion-exchanged water, lanthanum chloride heptahydrate (Kanto Chemical Grade 1) was added to the suspension to obtain 100.0 g of ion-exchanged water. The concentration was adjusted to 7.8 g of aluminum hydroxide and 7.1 g of lanthanum chloride anhydride.
(4) Hydrothermal treatment was performed with stirring at 130 ° C. for 2 hours in an autoclave (Om Labotech High Pressure Microreactor MMJ).
(5) The hydrothermally treated aluminum hydroxide suspension was dehydrated with a Buchner funnel. The dehydrated solid was washed with 50 times the amount of ion-exchanged water at 5 ° C.
(6) The washed aluminum hydroxide was resuspended in ion exchange water and adjusted to a concentration of 10 g of aluminum hydroxide with respect to 100.0 g of ion exchange water.
(7) The resuspended aluminum hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving net (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.

In the same manner as in Example 1, the mass of coarse particles, the mass of fine particles, sulfur content, particle size distribution, and specific surface area were measured.

<< Comparative Example 2 >> [Aluminum hydroxide]
In Example 2 (3), aluminum hydroxide washed with ion-exchanged water without using lanthanum chloride heptahydrate was suspended in ion-exchanged water, and aluminum hydroxide was added to 100.0 g of ion-exchanged water. The same treatment and measurement as in Example 2 were performed except that the concentration was adjusted to 7.8 g.
Further, the same measurement was performed for the comparative example in which the aluminum hydroxide obtained in (2) of Example 2 was washed in the step (5) (see “Washing the product before purification” in Table 2).

Table 2 summarizes the measurement results of the above Example 2, Comparative Example 2, and the product before purification.
As shown in Table 2, in Example 2, the separated crude stream contained a large amount of sulfate ions (sulfur), and sulfate ions were reduced in the fine particles. In addition, the sulfur content in the aluminum hydroxide before purification (state (2) of Example 1) was 1.03%.
Moreover, in Example 1, the particle diameter was equal in the range whose particle diameter is 20 micrometers or less.

Example 3 [Magnesium hydroxide]
Example 3 and Comparative Example 3 are examples relating to the removal of polyvalent anions and examples of producing high-purity and fine-grain magnesium hydroxide.
(1) A magnesium sulfate waste solution (Mg 31.6 g / l, SO ₄ 121.1 g / l) and a lithium hydroxide solution (lithium hydroxide monohydrate JIS special grade manufactured by Kanto Chemical Co., Ltd. diluted to 3.98 N in soft water) The liquid temperature was kept at 25 ° C., and a continuous reaction was performed at a reaction rate of 99% (Li ⁺ / Ni ²⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate magnesium hydroxide.
MgSO ₄ + 2LiOH → Mg (OH) ₂ ↓ + Li ₂ SO ₄
(2) The precipitated magnesium hydroxide was dehydrated with a Buchner funnel and then washed with 10 times the ion-exchanged water with respect to magnesium hydroxide.
(3) After suspending magnesium hydroxide washed with ion-exchanged water in ion-exchanged water, strontium nitrate (special grade made by Kanto Chemical) was added to the suspension and hydroxylated against 100.0 g of ion-exchanged water. The concentration was adjusted to 6.0 g magnesium and 19.9 g strontium nitrate.
(4) Hydrothermal treatment was performed with stirring at 150 ° C. for 2 hours in an autoclave (Om Labotech High Pressure Microreactor MMJ).
(5) The hydrothermally treated magnesium hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving net (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.
(6) The crude stream and fine particles were individually dehydrated with a Buchner funnel and washed with 10 times the ion-exchanged water in terms of solids of each dehydrated product.

(mass)
After drying at 105 ° C. for 1 hour, the mass of each of the coarse particles and fine particles was measured and the ratio was calculated.
(Sulfur content)
Each sulfur content in the coarse and fine particles was measured with a sulfur analyzer (Model EMIA-120 manufactured by Horiba Seisakusho).
(Boron content)
Boron in the coarse and fine particles was measured with an inductively coupled high-frequency plasma emission spectrometer (desktop ICP emission spectrometer SPS7800 manufactured by SII Nanotechnology).
(Phosphorus content, silicon content)
According to JIS K 0050, a sample is dissolved in hydrochloric acid to prepare a sample, and silicon and phosphorus in coarse and fine particles are measured with a fluorescent X-ray analyzer (element analyzer JSX-3201M manufactured by JEOL). did.
(Specific surface area)
Using an automatic specific surface area / pore distribution measuring device (BELSORP-mini, manufactured by Bell) E. T.A. Measured by the method.
(Particle size distribution)
The particle size distribution of fine particles was measured by a laser diffraction particle size distribution measuring device (Nikkiso Microtrac SPA7995). Moreover, the volume ratio of the part exceeding 20 micrometers among the measured fine particle part was calculated | required.

<< Comparative Example 3 >> [magnesium hydroxide]
In Example 3 (3), magnesium hydroxide washed with ion-exchanged water without using strontium nitrate was suspended in ion-exchanged water, and then magnesium hydroxide 6.10 g with respect to 100.0 g of ion-exchanged water. The same treatment and measurement as in Example 3 were performed except that the concentration was adjusted to 0 g.

Table 3 summarizes the measurement results of Example 3 and Comparative Example 3 described above.
As shown in Table 3, in Example 3, the separated crude stream contained a large amount of sulfate ions (sulfur), and sulfate ions were reduced in the fine particles. Similar to the sulfate ion, in Example 3, boric acid (boron), silicic acid (silicon), and phosphoric acid (phosphorus) were mostly contained in the separated coarse particles, and decreased in the fine particles.
In addition, the sulfur content in the nickel hydroxide before purification (state (2) of Example 3) was 0.81%.
Moreover, in Example 1, the particle diameter was equal in the range whose particle diameter is 20 micrometers or less.

<< Example 4-1 >> [Cobalt hydroxide]
In Examples 4-1 to 4 and Comparative Example 4, the impurity sulfate ion is fixed as a coarse sulfate, and it is practically possible to separate and remove by classification based on the particle size. It is the Example regarding.
(1) Cobalt sulfate waste liquid (Co 64.8g / l, SO ₄ 103.7g / l) and sodium hydroxide solution (sodium hydroxide JIS special grade manufactured by Kanto Chemical Co., Ltd. diluted to 4.02N in soft water) The mixture was kept at 25 ° C. and continuously reacted at a reaction rate of 99% (Na ⁺ / Co ²⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate cobalt hydroxide.
CoSO ₄ + 2NaOH → Co (OH) ₂ ↓ + Na ₂ SO ₄
(2) The deposited cobalt hydroxide was dehydrated with a Buchner funnel, and then washed with ion exchange water 5 times as much as the cobalt hydroxide.
(3) After suspending cobalt hydroxide washed with ion-exchanged water in ion-exchanged water, strontium nitrate (special grade made by Kanto Chemical) was added to the suspension, and hydroxylated against 100.0 g of ion-exchanged water. The concentration was adjusted to 9.0 g of cobalt and 25.4 g of strontium nitrate.
(4) Hydrothermal treatment was performed with stirring at 130 ° C. for 2 hours in an autoclave (Om Labotech High Pressure Microreactor MMJ).
(5) The hydrothermally treated cobalt hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving mesh (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.
(6) The coarse stream and fine particles were individually dehydrated with a Buchner funnel, and washed with ion exchange water 5 times in terms of solids of each dehydrated product.

(mass)
After substitution with acetone, the mixture was dried at 25 ° C. for 1 hour, and the mass of each of the coarse particles and fine particles was measured to calculate the ratio.
(Sulfur content)
Each sulfur content in the coarse and fine particles was measured with a sulfur analyzer (Model EMIA-120 manufactured by Horiba Seisakusho).
(Specific surface area)
Using an automatic specific surface area / pore distribution measuring device (BELSORP-mini, manufactured by Bell) E. T.A. Measured by the method.
(Particle size distribution)
The particle size distribution of fine particles was measured by a laser diffraction particle size distribution measuring device (Nikkiso Microtrac SPA7995). Moreover, the volume ratio of the part exceeding 20 micrometers among the measured fine particle part was calculated | required.

<< Example 4-2 >> [Cobalt hydroxide]
In Example 4-1 (3), measurement was performed in the same manner as in Example 4-1, except that the concentration of strontium nitrate was changed to 12.7 g of strontium nitrate with respect to 100.0 g of ion-exchanged water. .

<< Example 4-3 >> [Cobalt hydroxide]
In Example 4-1 (3), measurement was performed in the same manner as in Example 4-1, except that the concentration of strontium nitrate was changed to 6.4 g of strontium nitrate with respect to 100.0 g of ion-exchanged water. .

<< Example 4-4 >> [Cobalt hydroxide]
In Example 4-1 (3), measurement was performed in the same manner as in Example 4-1, except that the concentration of strontium nitrate was changed to 3.2 g of strontium nitrate with respect to 100.0 g of ion-exchanged water. .

<< Comparative Example 4 >> [Cobalt hydroxide]
In Example 4-1 (3), cobalt hydroxide washed with ion-exchanged water without using strontium nitrate was suspended in ion-exchanged water, and cobalt hydroxide was added to 100.0 g of ion-exchanged water. The same treatment and measurement as in Example 4-1 were performed except that the concentration was adjusted to 0 g.

Table 4 summarizes the measurement results of Examples 4-1 to 4 and Comparative Example 4 described above.
As shown in Table 4, in Example 4, the separated coarse particles contained many sulfate ions (sulfur), and the fine particles contained few sulfate ions.
The sulfur content before refining was 0.71% for the coarse particles and 0.68% for the fine particles.
Moreover, in Example 4, the particle diameter was equal in the range whose particle diameter is 20 micrometers or less.

Example 5 [Zinc hydroxide]
Example 5 and Comparative Example 5 are examples in which zinc hydroxide having high purity and fine particles was generated.
(1) Zinc sulfate waste liquid (Zn 58.4 g / l, SO ₄ 87.7 g / l) and sodium hydroxide solution (sodium hydroxide JIS special grade manufactured by Kanto Chemical Co., Ltd. diluted to 3.98N in soft water) The mixture was kept at 25 ° C. and continuously reacted at a reaction rate of 100% (Na ⁺ / Zn ²⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate zinc hydroxide.
ZnSO ₄ + 2NaOH → Zn (OH) ₂ ↓ + Na ₂ SO ₄
(2) The deposited zinc hydroxide was dehydrated with a Buchner funnel and then washed with ion exchange water 5 times as much as zinc hydroxide.
(3) After suspending zinc hydroxide washed with ion-exchanged water in ion-exchanged water, cerium nitrate hexahydrate (special grade made by Kanto Chemical) was added to the suspension to make 100.0 g of ion-exchanged water. On the other hand, the concentration was adjusted to 4.8 g of zinc hydroxide and 6.8 g of calcium acetate anhydrous.
(4) Hydrothermal treatment was performed with stirring in an autoclave (Om Labotech High Pressure Microreactor MMJ) at 90 ° C. for 2 hours.
(5) The hydrothermally treated zinc hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving net (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.
(6) The coarse stream and fine particles were individually dehydrated with a Buchner funnel, and washed with ion exchange water 5 times in terms of solids of each dehydrated product.

  In the same manner as in Example 4-1, the mass, sulfur content, particle size distribution, and specific surface area were measured.

<< Comparative Example 5 >> [Zinc hydroxide]
In Example 5 (3), except that zinc hydroxide washed with ion-exchanged water was suspended in ion-exchanged water and adjusted to a concentration of 4.8 g of zinc hydroxide with respect to 100.0 g of ion-exchanged water, The same treatment and measurement as in Example 5 were performed.

Table 5 summarizes the measurement results of Example 5 and Comparative Example 5 described above.
As shown in Table 5, in Example 5, the separated coarse particles contained a large amount of sulfate ions (sulfur), and the fine particles contained few sulfate ions.
Moreover, in Example 5, the particle diameter was equal in the range whose particle diameter is 20 micrometers or less.

Example 6 [Nickel hydroxide]
In Example 6 and Comparative Example 6, the sulfate ion as an impurity is fixed as a sulfate of coarse particles, and dissolved and removed with cold water using the increase in the solubility of sulfate in a low temperature region. It is an Example which produces | generates nickel oxide (equivalent to Claim 2).
(1) Nickel sulfate waste liquid (Ni 76.3 g / l, SO ₄ 127.7 g / l) and sodium hydroxide solution (diluted sodium hydroxide JIS special grade manufactured by Kanto Chemical Co., Ltd. in soft water to 4.04 N) The mixture was kept at 25 ° C. and continuously reacted at a reaction rate of 98% (Na ⁺ / Ni ²⁺ ) using a stirrer (Tsubaki Seisakusho TBN3-200 type) to precipitate nickel hydroxide.
NiSO ₄ + 2NaOH → Ni (OH) ₂ ↓ + Na ₂ SO ₄
(2) The deposited nickel hydroxide was dehydrated with a Buchner funnel, and then washed with ion exchange water 5 times the nickel hydroxide.
(3) After suspending nickel hydroxide washed with ion-exchanged water in ion-exchanged water, cerium acetate monohydrate (special grade made by Kanto Chemical) was added to the suspension to make 100.0 g of ion-exchanged water. On the other hand, the concentration was adjusted to 5.9 g of nickel hydroxide and 17.8 g of cerium acetate anhydride.
(4) Hydrothermal treatment was performed with stirring at 110 ° C. for 2 hours in an autoclave (OM Labtech High Pressure Microreactor MMJ).
(5) The hydrothermally treated nickel hydroxide suspension was dehydrated with a Buchner funnel. The dehydrated solid was washed with 50 times the amount of ion-exchanged water at 5 ° C.
(6) The washed nickel hydroxide was resuspended in ion exchange water and adjusted to a concentration of 10 g of nickel hydroxide with respect to 100.0 g of ion exchange water.
(7) The resuspended nickel hydroxide suspension was subjected to water sieving with a 325 mesh (44 μm) sieving net (manufactured by Yao Kinnet Seisakusho) to separate coarse and fine particles.

  In the same manner as in Example 1, the mass, sulfur content, particle size distribution, and specific surface area were measured.

<< Comparative Example 6 >> [Nickel hydroxide]
In Example 6 (3), except that nickel hydroxide washed with ion-exchanged water was suspended in ion-exchanged water and adjusted to a concentration of nickel hydroxide of 5.9 g with respect to 100.0 g of ion-exchanged water, The same treatment and measurement as in Example 6 were performed.

Table 1 summarizes the measurement results of Example 6 and Comparative Example 6 described above.
As shown in Table 1, in Example 6, the separated coarse particles contained a large amount of sulfate ions (sulfur), and sulfate ions decreased in the fine particles. Moreover, in Example 6, it turns out that a coarse particle content is only 0.3 mass% and it was preparing as a fine particle, without classifying. In addition, the sulfur content in the nickel hydroxide before purification (state (2) of Example 6) was 0.99%.
Further, in Example 6, the particle diameters were uniform in the range of 20 μm or less.

<< Example 7 >> [Mother solution purification]
In Example 7, the separated impurities are separated from the mother liquor, and the mother liquor is purified and reused.
(1) The coarse particles collected in the step (5) of Example 5, the filtrate, and the washing solution were suspended in a homogenizer (PT2100 manufactured by Polytron) for 5 minutes.
(2) Sulfur in the suspension was measured with a fluorescent X-ray analyzer (element analyzer JSX-3201M manufactured by JEOL Ltd.).
(3) Based on the measurement results, 8.0 times the amount of barium acetate (JIS special grade manufactured by Kanto Chemical Co., Inc.) is added to the total sulfur content of the suspension, and suspended for 5 minutes by a washing liquid homogenizer (PT2100 manufactured by Polytron). It was.
(4) After the suspension was cooled to 0 ° C., it was washed with a 10-fold amount of ion-exchanged water in terms of solid barium acetate and filtered with a Buchner funnel.

(mass)
The filtration residue was collected and dried at 105 ° C. for 1 hour, and the mass was measured.
(Barium, sulfur, zinc, cerium content)
The amount of sulfur, barium, and cerium in the dried filtration residue was measured with a fluorescent X-ray analyzer (element analyzer JSX-3201M manufactured by JEOL Ltd.).
(Sulfur separation rate)
The sulfur separation rate was calculated from the total weight of sulfur in the filtration residue measured by the quantitative analysis described above and the total weight of sulfur in the suspension.

<< Comparative Example 7 >> [Purification of mother liquor]
In Example 7, the same processing and measurement as in Example 7 were performed, except that the process (3) was not performed.
As shown in Table 7, in the filtration residue (solid content), barium and sulfur are fixed and zinc and cerium are reduced. As a mother liquor, sulfur is removed and cerium is contained. It was recovered.

<Example 8> [Purification of mother liquor]
In Example 8, the separated impurities are separated from the mother liquor, and the mother liquor is purified and reused. More specifically, it is a step of filtering and separating sulfur in the mother liquor as a solid using a decrease in the solubility of sulfate in a high temperature range.
(1) The coarse particles, filtrate, and washing solution collected in the step (5) of Example 3 were suspended in a homogenizer (PT2100 manufactured by Polytron) for 5 minutes.
(2) Sulfur in the suspension was measured with a fluorescent X-ray analyzer (element analyzer JSX-3201M manufactured by JEOL Ltd.).
(3) The suspension was hydrothermally treated at 140 ° C. for 10 minutes with an autoclave (OM Labtech High Pressure Microreactor MMJ).
(4) The solid content and the liquid content were separated from the suspension using a liquid cyclone (hydrocyclone NHC-10 type, manufactured by Nippon Chemical Machinery Co., Ltd.).

(mass)
The solid content was collected and dried at 105 ° C. for 1 hour, and the mass was measured.
(For sulfur and strontium)
The amount of sulfur and strontium in the dried filtration residue was measured with a fluorescent X-ray analyzer (element analyzer JSX-3201M manufactured by JEOL Ltd.).
(Sulfur separation rate)
The sulfur separation rate was calculated from the total weight of sulfur in the filtration residue measured by the quantitative analysis described above and the total weight of sulfur in the suspension.

<< Comparative Example 8 >> [Mother solution purification]
In Example 8, the same processing and measurement as in Example 8 were performed, except that the process (3) was not performed.
As shown in Table 8, in the filtration residue (solid content), strontium and sulfur were fixed and sulfate ions removed as impurities were removed from the mother liquor.

Example 9 [Comparative Example of Aluminum Hydroxide Flame Retardant]
(1) Homogenizer (ACE Homogenizer Japan Co., Ltd.) at a ratio of 1 part by weight of aluminum hydroxide to 10 parts by weight of soft water for the aluminum hydroxide obtained as a fine granule in (7) (final step) of Example 2 It was suspended by Seiki Seisakusho.
(2) The suspension is heated to 80 ° C., 0.04 parts by mass of lauric acid (JIS grade 1 manufactured by Kanto Chemical Co., Ltd.) is added to 1 part by mass of aluminum hydroxide, and a stirrer (Tsubaki Seisakusho TBN3-200 type) is added. And stirred for 5 minutes.
(3) After dehydration with a Buchner funnel, the dehydrated aluminum hydroxide was dried at 105 ° C. for 1 hour.
(4) 150 parts by mass of this dried aluminum hydroxide, 3 parts by mass of calcium stearate (manufactured by Sakai Chemical), and 100 parts by mass of an ethylene-vinyl acetate polymer resin (Evatate K2010, manufactured by Sumitomo Chemical) are heated at 130 ° C. for 5 minutes. Kneaded.
(5) The obtained sheet-like kneaded product was hot press molded at 130 ° C. for 10 minutes to prepare a molded product having a thickness of 3 mm.

(Oxygen index)
The oxygen index was measured based on JIS K7201-2. (Oxygen index method flammability tester Suga Tester ON-2N)
(Elongation)
The hot press molded product was measured for elongation at break according to JIS K7161 and K7162. (Strograph VE manufactured by Toyo Seiki Seisakusho)

<< Comparative Example 9 >> [Comparative Example of Aluminum Hydroxide Flame Retardant]
A material was prepared in the same manner as in Example 9 except that the aluminum hydroxide obtained in the final step of Comparative Example 2 was used, and the oxygen index and the elongation at break were measured.
Table 9 shows the measurement results of the oxygen index and the tensile elongation at break.
As can be seen from Table 9, the flame retardant resin of Example 9 has a low oxygen index and excellent flame retardancy. Moreover, elongation at the time of tensile fracture was large, and aluminum hydroxide was excellent in dispersibility.

<< Example 10 >> [Comparative Example of Flame Retardant Magnesium Hydroxide]
(1) Magnesium hydroxide obtained as fine particles in (6) (final step) of Example 3 was homogenized at a ratio of 1 part by weight of magnesium hydroxide to 10 parts by weight of soft water (ACE Homogenizer Japan Co., Ltd.) It was suspended by Seiki Seisakusho.
(2) The suspension is heated to 80 ° C., 0.04 part by mass of lauric acid (JIS grade 1 manufactured by Kanto Chemical Co., Ltd.) is added to 1 part by mass of magnesium hydroxide, and a stirrer (Tsubaki Seisakusho TBN3-200 type) is added. And stirred for 5 minutes.
(3) After dehydration with a Buchner funnel, the dehydrated magnesium hydroxide was dried at 105 ° C. for 1 hour.
(4) 150 parts by mass of this dried magnesium hydroxide, 3 parts by mass of calcium stearate (manufactured by Sakai Chemical), and 100 parts by mass of a polypropylene resin (E-200GP, manufactured by Idemitsu Petrochemical) were kneaded at 180 ° C. for 5 minutes. .
(5) The obtained sheet-like kneaded product was hot press molded at 180 ° C. for 10 minutes to prepare a molded product having a thickness of 3 mm.

(Oxygen index)
The oxygen index was measured based on JIS K7201-2. (Oxygen index method flammability tester Suga Tester ON-2N)
(Elongation)
The hot press molded product was measured for elongation at break according to JIS K7161 and K7162. (Strograph VE manufactured by Toyo Seiki Seisakusho)

Comparative Example 10 [Comparative Example of Magnesium Hydroxide Flame Retardant]
A sample was prepared in the same manner as in Example 10 except that the magnesium hydroxide obtained in the final step of Comparative Example 3 was used, and the oxygen index and the elongation at break were measured.
Table 10 shows the measurement results of oxygen index and tensile elongation at break.
As can be seen from Table 9, the flame retardant resin of Example 9 has a low oxygen index and excellent flame retardancy. Moreover, elongation at the time of tensile fracture was large, and aluminum hydroxide was excellent in dispersibility.

It is process drawing of the refinement | purification method (manufacturing method of a flame retardant) of the metal hydroxide concerning embodiment of this invention.

Claims (7)

(1) Impurities comprising a metal having a hydroxide solubility in water at 0 ° C. to 100 ° C. of 0.1 g or less and a sulfate having a solubility in water at 0 ° C. to 90 ° C. of 5.0 g or more. A metal hydroxide to be purified containing at least sulfate ions, and a metal having a solubility in water of 0 to 100 ° C. of sulfate of 0.1 g or less, and the solubility in water of 0 to 100 ° C. And a first metal salt having a weight of 1.0 g or more,
The metal hydroxide to be purified and the first metal salt are suspended in water, the metal hydroxide is 5 to 500 parts by mass, and the metal salt is 1.0 part by mass or more with respect to 100 parts by mass of water. Making a suspension of concentration;
(2) The suspension obtained in (1) is heated in the range of 90 ° C. to 250 ° C., and a divalent or higher anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 0 A step of precipitating as a metal sulfate having a solubility in water of 0.1 g or less at 100 ° C. to 100 ° C. and other salts of divalent or higher anions,
(3) Classifying the solids in the suspension heated in (2), or classifying the solid powder obtained after drying the suspension, and fine particles having a particle size of 44 μm or less And a step of separating a coarse particle fraction larger than 44 μm. (1) Impurities comprising a metal having a hydroxide solubility in water at 0 ° C. to 100 ° C. of 0.1 g or less and a sulfate having a solubility in water at 0 ° C. to 90 ° C. of 5.0 g or more. As a metal hydroxide to be purified containing at least sulfate ions, the solubility of sulfate in water at 100 ° C. is 5.0 g or less, and the solubility of sulfate in water in the temperature range of 0 ° C. to 90 ° C. Is a maximum value, or the solubility is negatively correlated with the temperature and the maximum solubility in water at 0 to 90 ° C. is 0.1 g or more, and the temperature is 0 ° C. to 100 ° C. Select a second metal salt having a solubility in water of 5.0 g or more,
The metal hydroxide to be purified and the second metal salt are suspended in water, the metal hydroxide is 5 to 500 parts by mass, and the metal salt is 1.0 part by mass or more with respect to 100 parts by mass of water. Adjusting the suspension to a concentration;
(2) The suspension obtained in (1) is heated in the range of 90 ° C. to 250 ° C., and a divalent or higher-valent anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 100 A step of precipitating as a metal sulfate having a solubility at 5.0 ° C. of 5.0 g or less and other salts of divalent or higher anions,
(3) After filtering the suspension heated in (2), the solid is washed with water at 50 ° C. or lower, and divalent or higher anions containing sulfate ions present as impurities are dissolved in water and removed. And a step of purifying the metal hydroxide. (1) Impurities comprising a metal having a hydroxide solubility in water at 0 ° C. to 100 ° C. of 0.1 g or less and a sulfate having a solubility in water at 0 ° C. to 90 ° C. of 5.0 g or more. As a metal hydroxide to be purified containing at least sulfate ions, the solubility of sulfate in water at 100 ° C. is 5.0 g or less, and the solubility of sulfate in water in the temperature range of 0 ° C. to 90 ° C. Is a maximum value, or the solubility is negatively correlated with the temperature and the maximum solubility in water at 0 to 90 ° C. is 0.1 g or more, and the temperature is 0 ° C. to 100 ° C. Select a second metal salt having a solubility in water of 5.0 g or more,
The metal hydroxide to be purified and the second metal salt are suspended in water, the metal hydroxide is 5 to 500 parts by mass, and the metal salt is 1.0 part by mass or more with respect to 100 parts by mass of water. Making a suspension of concentration;
(2) The suspension obtained in (1) is heated in the range of 90 ° C. to 250 ° C., and a divalent or higher-valent anion containing sulfate ions present as impurities of the metal hydroxide to be purified is converted to 100 A step of precipitating as a metal sulfate having a solubility at 5.0 ° C. of 5.0 g or less and other salts of divalent or higher anions,
(3) Classifying the solids in the suspension heated in (2), or classifying the solid powder obtained after drying the suspension, and fine particles having a particle size of 44 μm or less And coarse particles larger than 44 μm are separated, and the classified fine particles are washed with water at 50 ° C. or lower, and divalent or higher anions containing sulfate ions present as impurities are dissolved in water. And a step of removing the metal hydroxide.   The transition metal hydroxide produced by reacting the transition metal sulfate waste liquid discharged from the plating step or the metal etching treatment step with an alkali metal or ammonia is used in the method according to any one of claims 1 to 3. A method for producing a metal hydroxide, which is purified and recovered as a transition metal hydroxide.   The alkaline earth metal hydroxide produced by reacting alkali metal or ammonia with the alkaline earth metal sulfate waste liquid discharged in the flue gas desulfurization process after burning coal or heavy oil. A method for producing a metal hydroxide, which is purified by the method according to any one of the above and recovered as a high-purity alkaline earth metal hydroxide.   The method for purifying a metal hydroxide according to claim 1 or 3, further comprising:
(4) The coarse particles classified in (3) are made of a metal whose solubility in water at 0 ° C. to 100 ° C. of the sulfate is 0.1 g or less, and in the water at 0 ° C. to 100 ° C. A method for purifying a metal hydroxide, comprising a step of adding a third metal salt having a solubility of 1.0 g or more and recovering as a monovalent metal salt aqueous solution added in the step.   The method for purifying a metal hydroxide according to claim 1 or 3, further comprising:
(4) Suspend at least the coarse particles classified in (3) and the liquid in the suspension of (3), heat to 90 ° C. to 250 ° C., and hydrothermally treat the solid and liquid components. A method for purifying a metal hydroxide, comprising a step of separating and recovering as a monovalent metal salt aqueous solution added in the step.

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