KR930003750B1 - Process for manufacturing magnesium hydroxide - Google Patents

Abstract

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Description

Synthesis method of active magnesium hydroxide

1 is a graph comparing the reactivity for samples A, B, C, D, E.

The present invention is a high activity hydrogel-type magnesium hydroxide (hereinafter referred to as "hydromagnesia) in the digestion reaction with water to calcinate naturally produced magnesite (MgCO ₃ ) to form a light magnesium (MgO). "," Is referred to. In addition, digestion is called synthesis of magnesium hydroxide by reaction of light magnesium with water. Most of the small magnesia is produced and imported from China. Ore contains magnesite (MgCO ₃ ) as a main component and contains impurities such as herebrandite (Ca ₂ SiO ₄ · H ₂ O) and trace amounts of forsterite (Mg ₂ SiO ₄ ).

By firing this ore at around 800 ° C, the magnesite turns into periclase type MgO, the herbbrandite of impurities turns to ralsite, and forsterite remains in its approximately previous state. The fine pulverization of this calcined ore is called light magnesium.

In Japan, this light magnesia is imported as a raw material of goto fertilizer. Since the light magnesium is MgO, it can be used as an alkaline agent, especially if it can be used as an alkaline agent for flue gas desulfurization, it can supply less than half of the production coast of seawater magnesia currently produced from seawater in Japan, It will be saving and energy saving. Therefore, many people have tried to use it as the alkali agent.

However, the light magnesia is poor in reaction characteristics as an alkaline agent. That is, ① insoluble in water. ② Reactivity (digestion) with water is slow. ③ Digested magnesia is less responsive than seawater magnesia, and various modifications have been attempted, but the reaction characteristics could not be improved. This has been interpreted to be fatal due to the pericle type crystal structure of small and small magnesia (a wheat packing structure in which Mg atoms are surrounded by six O atoms).

However, as a result of intensive research, the inventors have found that the antipyretic structure of the pericle-type structure increases the OH ^- ion concentration of the liquid by adding NaOH, and 4 to 5 of the 6 O atoms are changed to OH ⁻ , Two O atoms were found to be active radicals of the free radical type.

Since it has this free radical atom, the reactivity becomes extremely large and has a reaction rate constant of 4 to 5 times that of seawater magnesia. In particular, the reaction rate is high at high pH.

In the synthesis of hydromagnesia, in order to increase the reaction rate of hydrolysis, the temperature of the synthesis liquid is set to 85 ° C or higher, preferably 95 ° C or higher, and a strong alkaline agent such as caustic soda is added to dissolve the pericle structure. Is measured at room temperature to 11 or more, preferably 12 or more. The reaction time is 20 minutes or more and about 5 hours, preferably 1 hour to 3 hours, and the mixture is sufficiently stirred to complete the reaction.

The initiation of the antipyretic reaction starts at about 10 minutes after the start of the synthesis, for example, at a synthesis liquid temperature of 95 ° C., and 90% proceeds within 60 minutes.

Next, the Example of this invention is described in detail.

After filling 10 ㎥ of industrial water into a 15 ㎥ reaction tank equipped with an iron stirrer and stirring, the solution was heated with steam to 50 ° C., and then the steam was stopped. 30 kg of flake caustic soda is added to this, and it fully melt | dissolves. Subsequently, when 4000 kg of light magnesia is added and mixed and stirred, it becomes a reaction tank liquid temperature of 100 degreeC within 20-30 minutes. The reaction is completed by reacting for 2 to 3 hours while adjusting the temperature with steam so that the temperature does not decrease. The synthetic solution is cooled down to hydromagnesia as a product.

Hydromagnesia differs from seawater magnesia and is extremely low viscosity and can be transported and stored as a high concentration slurry (45%). This hydromagnesia makes a significant contribution to cost reduction and energy reduction, as is the normal term as an alkaline agent for upset stomach.

Next, Table 1 and Table 2 show comparative measurements of the physical properties and reactivity of the hydromagnesia of Examples of the present invention with seawater magnesia from each company.

In addition, the comparison of reactivity was shown by the graph again clearly.

Sample A seawater magnesia (product made in A company)

"B" (A company)

"C" (A company)

"D" (S company made)

"E hydromagnesia (inventive examples herein)

TABLE 1

TABLE 2

(Reactivity)

* Measurement condition: Viscosity-B viscometer / NO. 2 rotor use

Liquid temperature = approximately 20 degrees Celsius

Viscosity Distribution-Cedigraph / Solvent = Water

Liquid temperature = 34-35 degrees Celsius

Heavy weight = 2.41

Reaction with 200 cc (0.2 mol) of reactive-2N sulfuric acid

Liquid temperature at the time of reaction = about 45-50 degreeC

Concentration of sample = 0.208mol

Claims (5)

Highly active and hydrogel type reaction was carried out by the digestion reaction of finely divided small magnesia with water while stirring the reaction temperature at 85 ° C or higher, pH 11 or higher, 20 minutes or longer for 5 hours. A method for synthesizing active magnesium hydroxide, comprising synthesizing magnesium hydroxide. The method for synthesizing active magnesium hydroxide according to claim 1, wherein the light magnesium is finely divided into 5 to 30 µ. The method for synthesizing active magnesium hydroxide according to claim 1 or 2, wherein the reaction temperature is 95 ° C or higher. The method of synthesizing active magnesium hydroxide according to claim 1 or 2, wherein the liquidity is pH 12 or more. The method for synthesizing active magnesium hydroxide according to claim 1 or 2, wherein the reaction time is 1 to 3 hours.

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