JPS61500783A - Alkali metal hydroxide purity improvement method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a method for increasing the purity of alkali metal hydroxides.

Sodium hydroxide and other alkali metal waters produced by known means Oxides, as well as some carbonates, cannot be manufactured, stored, used or may contain inorganic contaminants derived from each Kashihara associated with regeneration. these contaminations Sources include raw materials, chemical reactants, feed water, and industrial plant components. Conventional In one known branch of the process, an alkali metal hydroxide is an alkali metal carbonate. consisting of or consisting of salts, alkali metal bicarbonates or alkali metal organic salts. A substance containing the general formula (M2O)a・(R bOc) a salt or mixed oxide of a is obtained, where M is an alkali metal (e.g. , Na, K), and R is a transition metal (e.g., T1.Fe); a salt or mixed oxide is hydrolyzed to produce an alkali metal hydroxide. Therefore, it is manufactured or reproduced.

This review of conventional methods for the production or regeneration of alkali metal hydroxides is well documented in the patent literature and and technical publications (e.g. Australian Patent 450,309.486,132.5 19+156; K11sk11a, F,, Paperi Puu 6 2’(5) + Ro 59450 (1980)), and the following: The rest will be referred to as ``Conventional Law Technique A''.

The method of the present invention has particular, but not limited to, application to the conventional method technology category mA. can.

Although the present invention is not limited to this case, the present invention is based on the conventional law technical category IIA. The material is produced from sulfur-free alkaline pulping of wood or plastic cellulosic materials. Used to regenerate sodium hydroxide from slurry waste liquor (e.g. black liquor) When the transition metal amphoteric oxide used in the above is ferric oxide, even more Particularly suitable.

In the sulfur-free alkaline pulping waste liquid, some hydroxide (IJ) However, the major portion of the sodium usually present is a combination of carbonates and organic salts. It is in the form of hot hardware. Sulfur-free acetate using ferric oxide in accordance with conventional method technology standard QA When regenerating sodium hydroxide from lukewarm pulping waste, The liquid is concentrated by evaporation and then warmed with ferric oxide in air, usually at 750% Calcining to temperatures within the range of 1000°C to combust organic matter and remove sodium chloride. form umferrite. D-oral decomposition of sodium ferrite in hot water Sodium hydroxide@liquid and solid ferric oxide are obtained, which are separated from each other and then separated into powder. It can be reused for repeated purification and alkaline regeneration. Sodium hydroxide @Liquids usually contain a small proportion of unreacted sodium carbonate. Combustion during the firing stage is Organic salts of IJ (carbonate) are converted to IJ, which is originally contained in the pulping waste liquid. Together with the sodium carbonate present, it reacts with the ferric acid, producing mainly β -Sodium ferrite and carbon dioxide are thought to form the sulfur. child The latter reaction of is expressed as %formula% is expressed by

The subsequent hydrolysis of β-sodium ferrite is expressed by Equation 2% is expressed by

alkali metal hydroxides by one or other embodiments of the conventional techniques; During production or reclamation, transition metal amphoteric oxides can be used to remove a particularly substantial amount of inorganic contaminants. may be undesirable or unsuitable for certain applications. make it something. The chemical elements present as contaminants in alkali metal hydroxides are At least some are not readily amenable to purely mechanical removal means such as filtration can be in the form of a soluble or colloidal dispersion, and the amphoteric oxide is used. containing the transition metal used and also originally as an impurity in its amphoteric oxide. Contains the elements present. Impurities in transition metal amphoteric oxides are caused by the presence of naturally occurring ores (e.g. Even if the ore is in the form of hematite, ilmenite) This is especially common even if some ore processing has been carried out. Ability to use naturally produced ores are less expensive than transition metal amphoteric oxides in their synthetic or highly purified forms. Therefore, it is desirable.

Aluminum, silicon, iron, and manganese are classified according to Conventional Technique 111iA. Elements that may be present in sufficient quantities as contaminants in the resulting alkali metal hydroxide Among these are the production of paper pulp from lignocellulose materials and the production of rayon. This would be undesirable in applications such as soap production. example For example, in the production of paper pulp from lignocellulose materials, aluminum In a heat exchanger in contact with the pulping waste, the aluminum and silicon are mixed with canclinite and anal. Sites containing minerals such as sludge and scale deposits can form Ru. Iron and magnesium can also be mixed in such mineral deposits, but During aging or when oxygen is present during pulping or pulp bleaching operations. catalyzes the oxidative deterioration reaction of pulp fibers when used as a reactant, catalyzes the decomposition/decomposition reaction of hydrogen peroxide when used as a whitening agent It is possible to do so.

The present invention is primarily aimed at reducing the aluminum content of contaminated alkali metal hydroxides. However, the application of the method also applies to iron We have discovered that mitigation of other pollutants, including It is.

The present invention is characterized by the minimization of contaminants, since the contaminants are not produced by alkali metal hydroxides. or by preventing it from entering the solution when it is produced. by removing contaminants from contaminated solutions of genus hydroxide; be able to. In either case, the present invention provides a method for rendering contaminants insoluble. Utilizes alkaline earth compounds, thereby introducing contaminants into alkali metal hydroxide solutions. Reduce dye ingress or remove contaminants from contaminated solutions of alkali metal hydroxides. Accelerates removal of dyes. In the latter case, in dissolved form in solution or in other At least some of the pre-existing contaminant content in difficult-to-separate forms can be removed by filtration, sedimentation or centrifugation. or mixed into a separable phase by similar solid-liquid separation means.

Suitable alkaline earth compounds include alkaline earths (e.g. Mg, Ca, 3rr Ba) carbonate, basic carbonate, oxide, hydroxide, or water-bathable organic or inorganic salts. Two or a mixture of two or more of these compounds or Compounds within these categories but containing more than one alkaline earth metal may also be used.

Magnesium is an alkaline earth in a preferred embodiment of the invention.

Contaminants that can be removed by the method of the invention include aluminum and iron.

When the alkaline earth compound used is a magnesium compound (ζ suitable for the present invention) When aluminum becomes insoluble due to use, its form can be determined by X-ray diffraction analysis. was shown to be primarily hydrotalcite, and similar aluminum Compounds containing alkaline earth metals other than magnesium may be used in the application of the present invention. Although it is thought to be formed when using When so used, the use of insoluble or sparingly soluble aluminum compounds Other types of alkaline earths may form, or insoluble or slightly soluble alkaline earths. of aluminum-containing compounds or ions on or by similar compounds. The possibility of sorption or occlusion must also be considered.

Contaminants other than aluminum can be removed from alkali metal hydroxide solution by application of the present invention. The form that makes it more insoluble has not yet been clearly elucidated.

Regarding the prior art area aiA, the alkaline earth preference to be used according to the invention is Alternatively, magnesium compounds can be prepared by adding an alkali metal hydroxide solution to a modified amphoteric acid. introduction into or contact with a substance after separation from it However, in particularly preferred embodiments of the invention, at an early stage introduced, it is present during and/or immediately after the water splitting operation and its solidification The amphoteric reaction product is denatured when it is separated from the alkali metal hydroxide solution. It can be carried out such that the oxide is then entrained.

Hydrotalcite contains carbonates, so if aluminum is used in this form or other alkali In order to be removed in the form of potassium earth analogues, one carbonate source can be removed according to the present invention. must exist during the application of the law. In the case of technical scope defect A under the U.S. law, normally existing The residual alkali metal carbonate present is usually sufficient.

cost, effectiveness, and retention of contaminating water-soluble anions in alkali metal hydroxides. Magnesium oxide is a preferred embodiment of the present invention from the overall consideration of avoiding It is an alkaline earth compound used in to use in its embodiment An economical means of obtaining suitable magnesium oxide is from magnesite or dolomite. Including grilled eel naturally produced carbonate substances.

■When using baked dolomite, aluminum is mainly composed of calcium oxide. It is made insoluble by the reaction of the magnesium oxide component.

Alkali metal hydroxide solutions can be used at any temperature within the range from the freezing point to the boiling point of the solution. It can be treated with alkaline earth compounds at temperatures of

When the alkali metal hydroxide bath solution comes into contact with the alkaline earth compound, the The rate and extent to which all of a given impurity already dissolved in the solid phase is transferred to the solid phase The nature of the alkaline earth compound used, its manufacturing history and amount, as well as the temperature of the contact mentioned above. It depends on several factors including intensity, duration and even density.

Conditions set forth in the examples hereinafter presented as illustrations of the mode of operation of the invention does not represent the entire range of conditions under which non-invention may be applied, and does not represent the entire range of conditions under which non-invention may be applied. It is not about concreteness.

Example 1 Clarified by centrifugation and contains 5.56 mol/' of total sodium of 9 and 89.1 % of caustic ffi & sodium hydroxide solution, sulfur-free alkali solution Manufactured from pulping waste liquid and hematite ore in accordance with the embodiment of the Japanese Law Technology Category Ou A. Ta. Natural dolomite was baked at 1100'C for 2 hours to give a mass of 25.2' A granular product containing 4 magnesium was obtained and allowed to cool.

Each approximately 80y portion of this sodium hydroxide solution was heated to 80°C, and various amounts Mix it with the calcined dolomite and heat it immediately at 80℃ for 30 minutes while keeping the temperature. The mixture was stirred thoroughly and then filtered without pre-cooling. Another layer of this sodium hydroxide solution Two equal parts of smoked dolomite or other additives were not used. were treated in the same way.

Chemical analysis of the above parts of IJium (hydroxide after treatment) was performed without contacting with additives. The aluminum and iron parts are 7.59 y/kg’Na and 0.0 56!　/　kg’Na is contained in the part treated with ■burned dolomite. showed that the levels of those impurities were lower by the percentages shown in Table 1. did.

Bath liquid (y) (y) AI Fe 80.13 1.25 98 99 80.16 0.62 81 99 Another untreated sodium hydroxide solution with a mass of 80.05 g of the solution of Example 1 was added. One part was treated in the same manner as described in Example 1, except that: Added 0.427 & laboratory grade magnesium oxide instead of 7100 .

Chemical analysis of the treated sodium hydroxide solution showed that the aluminum and iron contents were The results showed that the values were 87% and 99% lower than in the liquid treated without the added JJO agent, respectively. did.

Example 6 5.42 mol/kl? liquid water with a total sodium content of 83.8% and a causticity of 83.8% Sodium oxide solution is mixed with hematite ore according to the embodiment of conventional technology category A. Made from laboratory-grade sodium carbonate. 80° part of 33.85y of this solution 50.0451, mixed with laboratory grade magnesium sulfate pentahydrate, and directly Stir vigorously for 30 minutes, maintaining the temperature, then without pre-cooling. Ku! passed. A second equal amount of this sodium hydroxide’magnesium tfmate The process was the same except that no gum or other additives were used.

For chemical analysis of each part of the IJium solution after treatment, ensure that it does not come into contact with additives. The dark parts are aluminum and iron, respectively 28.617 kg, Na and skin 248 kg. 'l　/　kg・Na, while inside the part treated with magnesium sulfate at ℃ showed that their impurity levels were 80% and 97% lower, respectively.

Example 4 Contains β-sodium ferrite and has a Fe:Na molar ratio of 1.42 Sulfur-free alkaline pulping waste obtained by evaporating granular solids according to conventional method technology category A Calcining the mixture of liquid and hematite in air and allowing the product to cool. Obtained by. Natural dolomite was baked at 1100℃ for 2 hours and cooled, and the mass 25.2 pieces of granular solid containing magnesium were obtained. β-sodium ferrite 100y of solids containing 4.40y of baked dolomite are mixed, then 6Qmt The ferrite is mixed with distilled water and continuously stirred at 80°C for 1 hour to undergo water decomposition. The resulting sodium hydroxide was allowed to leach into the solution. Its sodium hydroxide solution The liquid was then filtered twice without pre-cooling. A second layer of sodium ferrite-containing solid The same amount of dolomite was processed in the same manner, except that time-fired dolomite was not used.

Chemical analysis of these two sodium hydroxide solutions gave the results shown in Table 2. The sodium hydroxide solution made in the presence of mite has 79% less a It was shown that it contains luminium.

Total sodium Causticity A1 Mol/L%’j 7kg・Na ■Burned dolomite 5.96 90.3 7.05 Not used Example 5 Example 10 Granular hardened dolomite was ground into powder. Total sodium content is 6.12 Impure hydroxide (mol/kg) and causticity of 86.6%) IJum@liquid Heat the 200.8y part of to 100°C, 2.53! Powdered ■Grilled Doroma of ¥ and immediately placed under continuous vigorous stirring while maintaining the above temperature. water 6 to 60 minutes from initial contact between the sodium oxide bath and the calcined dolomite At a time interval ranging from and extracted from the reaction mixture. Impure sodium hydroxide l) The second part of the rum was heated to 100°C. He heats up, dolomite or other additives 710? It was filtered without addition.

The analysis of the hydroxide (IJum) sample treated without using dolomite 8.52 each! 9・Na in i/ and 9・Na in 0.045'l/' Indicated the content of aluminum and iron.

■Analysis of samples of sodium hydroxide @ liquid treated with calcined dolomite The impurity content was shown to be lower by the percentages shown in Table 6.

The invention in its general aspects is not limited to the specific details cited above. It will be clearly understood.

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Claims (16)

[Claims] 1. Alkali metal carbonates, alkali metal bicarbonates or organic salts of alkali metals or by heating substances consisting of or containing organic salts with amphoteric oxides of transition metals. Then, M is an alkali metal and R is a transition metal, the general formula (M20)a.(RbO c) forming a salt or mixed oxide of d, which salt or mixed oxide is then hydrolyzed; solution and leaching to form a solution of alkali metal hydroxide, and the transition gold any method that leaves behind a solid residue consisting of or containing amphoteric oxides of the genus A method for improving the purity of an alkali metal hydroxide produced or regenerated by: Alkali metal hydroxides by adding one or more alkaline earth compounds reacts with potential contaminants of the solution to form relatively insoluble compounds; When separating the above solution from the solid residue of the amphoteric oxide by alkali metal water A method characterized in that it reduces the amount of said contaminants appearing in an oxide solution. . 2. The claimed alkaline earth compound or compounds are added before the hydrolysis operation. The method described in Scope No. 1. 3. The claimed alkaline earth compound or compounds are added during the hydrolysis operation. The method described in box 1. 4. After the hydrolysis operation, the alkaline earth compound or compounds are The alkali metal hydroxide solution is mixed with a residue consisting of or containing amphoteric oxides of transition metals. 2. The method of claim 1, wherein the addition is made prior to separation from the distillate solids. 5. The alkaline earth compound or compounds are alkaline earth carbonates, basic carbonates, Claims selected from salts, oxides, hydroxides, and water-soluble organic or inorganic salts. The method described in item 1 of the scope. 6. The method according to claim 1, wherein the alkaline earth compound is magnesium. . 7. Claims in which the alkaline earth compound is dolomite or calcined dolomite The method described in paragraph 1. 8. Alkali metal carbonates, alkali metal bicarbonates, or alkali metal organic Substances consisting of or containing salts or inorganic salts are is the effluent resulting from the sulfur-free alkaline pulping of other natural materials, including fibers, A method according to claim 1. 9. The alkali metals are sodium and/or potassium and the transition metals are iron and 2. The method according to claim 1, wherein the material is titanium and/or titanium. 10. Contaminants or potential contaminants in alkali metal hydroxide solutions 2. The method according to claim 1, wherein the metal is iron and/or iron. 11. A method for purifying contaminated alkali metal hydroxide, the method comprising; A solution of an alkali metal hydroxide is combined with one or more alkaline earth compounds. contact to precipitate relatively insoluble forms of the contaminant and remove precipitated compounds from solution A method characterized by: 12. Alkaline earth compound or compounds are alkaline earth carbonates, basic carbonates Claims selected from salts, oxides, hydroxides, and water-soluble organic or inorganic salts. The method according to item 11. 13. 12. The method of claim 11, wherein the alkaline earth is magnesium. 14. Claim 11, wherein the magnesium compound is baked dolomite. the method of. 15. Claim No. 1, wherein the alkali metal is sodium and/or potassium. The method described in Section 11. 16. According to claim 11, the contaminant is aluminum and/or iron. the method of.