KR101300229B1 - Method for preparing magnesium hydroxide from bitterns - Google Patents

Abstract

The present invention relates to a method for producing magnesium hydroxide from juice, (a) mixing and diluting dilution water in a juice containing magnesium; (b) mixing the alkaline solution with the diluted juice to form magnesium hydroxide particles; (c) stirring the mixed mixture to grow magnesium hydroxide particles; (d) adding a seed to the mixed solution; (e) aging the mixed solution, separating the precipitate through filtration to obtain magnesium hydroxide; Magnesium hydroxide prepared according to the present invention is not only a low production cost in spite of the by-products generated in the decontamination plant, but also capable of producing magnesium hydroxide having dispersibility and high purity, and higher purity than magnesium hydroxide prepared from minerals. Magnesium hydroxide with high dispersibility can be manufactured, and it has excellent dispersibility and can be used as a flame retardant, which is an additive such as rubber and plastic. This can greatly contribute to the recycling of resources as well as providing cheaper materials.

Description

METHOD FOR PREPARING MAGNESIUM HYDROXIDE FROM BITTERNS}

The present invention relates to a method for producing magnesium hydroxide from the juice, a method for producing magnesium hydroxide from Bitterns, a by-product generated in the decontamination plant, the magnesium hydroxide prepared according to the present invention is a by-product generated in the decontamination plant In spite of the low manufacturing cost, it is possible to manufacture magnesium hydroxide with dispersibility and high purity, and it is possible to manufacture magnesium hydroxide with higher purity than magnesium hydroxide manufactured from minerals. It can be used as a flame retardant, which is an additive of, and can be used as a part material of semiconductor process when it is converted to magnesium oxide through a sintering process. have.

In general, magnesium hydroxide is used as a raw material of magnesia, which is a basic refractory material, and recently, as a flame retardant which is added to rubber and plastics and does not burn well, it is increasing. In addition, as the IT industry develops, the use of high-purity magnesium oxide as a semiconductor process component material is increasing. As such, in order to use magnesium hydroxide as a flame retardant, not only high purity but also dispersibility must be excellent.

Magnesium hydroxide production methods include a method of using brucite or natural magnesite, a method of using seawater or brine, and a method of using magnesium chloride. Among the above methods, the method of using brucite or natural magnesite has a problem in that magnesium hydroxide of high purity cannot be obtained by purifying brucite or calcining and hydrating the natural magnesite.

In addition, the method of using seawater or brine among the above manufacturing method can produce magnesium hydroxide by reacting seawater or brine with alkali and obtain high-purity magnesium hydroxide, but the particles produced are present as fine particles and aggregated in a circular shape. There is a problem that is difficult to distribute.

Representative prior art for producing magnesium hydroxide is to prepare a high-purity magnesium hydroxide of MgO 99.3% or more by using B ₂ O ₃ adsorption resin, but such magnesium hydroxide is formed by the reaction of magnesium ions extracted from seawater with lime oil and cohesiveness It cannot be used for additives requiring dispersion (Japanese Patent Laid-Open No. 5-238725). In addition, magnesium hydroxide is prepared by hydrothermal treatment of magnesium chloride and alkali and magnesium oxide, and thus, high purity and high dispersibility of magnesium hydroxide can be produced, but there is a problem in that the manufacturing cost is too high and there is no economic efficiency (Japanese Laid-Open Patent Publication). 2000-233924). In Korea, there is a method of preparing magnesium hydroxide by appropriately treating magnesia prepared from seawater using magnesia manufactured from seawater as a raw material, but there is a problem that the manufacturing process has to go through multiple steps. .

In addition, the prior art uses a fine powder produced as a by-product during the process of manufacturing magnesium hydroxide using natural minerals such as brucite or natural magnesite, or magnesia from seawater to produce magnesium hydroxide, There is a problem that the manufacturing cost is relatively high.

The present invention was derived to solve the above problems of the prior art, an object of the present invention is to provide a method for producing magnesium hydroxide from the waste juice discharged from the decontamination process simply and economically.

In addition, another object of the present invention is to adjust the sodium hydroxide, which is an alkali substance (NaOH, Ca (OH) ₂ , NH ₄ OH, etc.) to an appropriate molar ratio with respect to magnesium ions contained in the juice and also to adjust the magnesium hydroxide produced during the manufacturing process By using as a seed, it is possible to provide a method for producing magnesium hydroxide having low production cost and high purity by shortening the recovery amount and production time of magnesium hydroxide and increasing the stirring speed.

The present invention is a means for solving the above problems, (a) mixing and diluting dilution water to the juice containing magnesium; (b) mixing the alkaline solution with the diluted juice to form magnesium hydroxide particles; (c) stirring the mixed mixture to grow magnesium hydroxide particles; (d) adding a seed to the mixed solution; And (e) aging the mixed solution and separating the precipitate through filtration to obtain magnesium hydroxide. It provides a magnesium hydroxide manufacturing method comprising a.

Preferably, in the step (a), the diluent is water or sea water, it is characterized in that the dilution by adding water or sea water in a ratio of 1: 1 to 1:20 relative to the juice.

Preferably, the alkaline solution of step (b) comprises sodium hydroxide, and when mixed, the molar ratio (Mg: Na molar ratio) of the juice and the sodium hydroxide is characterized in that 1: 1 to 1: 5.

Preferably, the reaction temperature at the time of mixing is 20 ℃ to 80 ℃, characterized in that the mixing speed is stirred within 10 minutes at 50 rpm to 100 rpm.

Preferably, the alkaline solution of step (b) is characterized in that it comprises Ca (OH) ₂ or NH ₄ OH.

Preferably, in the step (c), the reaction temperature during stirring is 20 ℃ to 80 ℃, characterized in that the stirring speed is stirred for 10 minutes to 150 minutes at 50 rpm to 500 rpm.

Preferably, the seed of step (d) comprises magnesium hydroxide, characterized in that the addition of 2.5 to 15% by mass of magnesium hydroxide relative to the concentration of magnesium contained in the mixture when added.

Preferably, in the step (e), the reaction temperature during aging is 20 ℃ to 80 ℃, characterized in that the stirring speed is stirred for 10 minutes to 150 minutes at 100 rpm to 500 rpm.

Preferably, after the step (e), characterized in that to wash the magnesium hydroxide of the precipitate using water or sea water.

Preferably, the magnesium hydroxide of the washed precipitate is dried.

Preferably, the washed and dried magnesium hydroxide is calcined at 300 ° C to 1000 ° C to produce magnesium oxide.

Preferably, the wastewater collected after the washing is recycled to the dilution water of the dilution step.

Preferably, the wastewater collected after the filtration is recycled to the dilution water of the dilution step.

According to the present invention, it is possible to effectively recycle magnesium, which is a useful metal contained in the high juice, which is a liquid waste, in a decontamination plant, and to produce magnesium hydroxide having high purity and excellent dispersibility.

In addition, the filtration time is shortened and the recovery rate is excellent in the manufacturing process of magnesium hydroxide, there is an effect that the manufacturing process is simple and economically can be produced magnesium hydroxide.

In addition, since the purity and the manufacturing process is simpler than magnesium hydroxide produced from natural minerals, there is an effect that it is possible to recover magnesium, as well as magnesium hydroxide, by recovering magnesium, which is a useful metal from infinite marine resources.

1 is a process diagram schematically showing an embodiment according to the present invention.
Figure 2 is a flow chart for explaining a method for producing magnesium hydroxide according to the present invention.
Figure 3 is a graph of the result of measuring the effect of the filtration time according to the precipitation time in accordance with embodiments of the present invention.
4 is a view showing a state of the supernatant after filtration according to the precipitation time according to embodiments of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention provides a method for producing magnesium hydroxide from Bitterns, a byproduct of the decontamination process.

Magnesium hydroxide production method according to the present invention comprises the steps of mixing magnesium and alkali metal useful metal contained in the high juice liquid waste generated in a salt factory to form magnesium hydroxide particles, stirring step for growing the magnesium hydroxide particles formed , Seed mixing to increase magnesium hydroxide recovery and filtration rate, aging the mixture, and crystallizing the mixture.

Here, the high juice contains a high concentration of various ions (Na, K, Ca, etc.), so the magnesium hydroxide particles are hindered when mixed with an alkaline substance, so the water must be diluted with water or sea water. The recovery of magnesium hydroxide increases only when it is reacted with alkaline solution.

Therefore, the juice is diluted with water or seawater in a dilution ratio of 1: 1 to 1:20, and when the mixture is mixed with the alkali to form particles of magnesium hydroxide, the alkali is 1: 1 for the concentration of magnesium contained in the juice. It is preferable to supply the alkali substance in a ratio of 1 mol to 1: 5 mol. In addition, the reaction temperature is preferably carried out at a temperature of 20 to 80, the mixing rate is preferably stirred within 10 minutes at 50 to 100 rpm.

In the stirring step for growing the magnesium hydroxide particles formed in the mixture, the reaction temperature is preferably carried out at a temperature of 20 to 80 ℃, the stirring speed is preferably stirred for 10 to 150 minutes at 50 to 500 rpm.

In addition, the seed mixing step to increase the magnesium hydroxide recovery rate and filtration rate is added to the magnesium hydroxide from 0.25% by mass to 5% by mass relative to the magnesium concentration to promote the growth of magnesium hydroxide to grow the nuclei of magnesium hydroxide of the fine particles In this case, the stirring speed is preferably stirred for 10 to 150 minutes at 50 to 500 rpm.

The step of ripening the mixture and the step of crystallizing the mixture is preferably carried out at a reaction temperature of 20 to 80 ℃, the stirring speed is preferably stirred for 10 to 150 minutes at 100 to 500 rpm.

In addition, the method of the present invention may further comprise the step of calcination, washing and drying the magnesium hydroxide prepared above, the wastewater collected after filtering and washing the prepared magnesium hydroxide is the juice and the It can be used again with dilution water used for mixing.

1 is a process diagram schematically showing an embodiment according to the present invention, Figure 2 is a flow chart for explaining a method for producing magnesium hydroxide according to the present invention.

Referring to Figures 1 and 2, the method for producing magnesium hydroxide from the juice is prepared by adding 20 ml of juice in the reaction tank and distilled water or sea water at a dilution ratio of 1: 1 to 1:20 to prepare diluted juice.

At this time, the diluted juice is mixed well with a stirrer and the initial pH of the diluted juice is measured, and then NaOH solution, one of alkaline substances, is added to the juice diluted in a ratio of 1 to 5 moles. 20 ml is added and stirred at 100-500 rpm for 10-150 minutes.

In the case of the alkali substance used here, the amount added will depend on the molar ratio of magnesium contained in the final juice required, but as a result of the basic investigation of the present invention, it is generally about 1 to 5 moles.

After stirring the reaction for 10 minutes to 150 minutes, the final pH of the reactants is measured, placed in a pressure filter, and the supernatant and the precipitate are separated.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide.

In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Magnesium hydroxide prepared by the above method can be used as a non-toxic flame retardant, chemical additives, medicinal antacids, alkali desulfurization process, and when the magnesium hydroxide is calcined at a high temperature can also be used as a high value magnesium oxide.

The following examples provide specific experimental examples for confirming the effects of the present invention, which are intended only to illustrate the present invention and confirm the effects thereof, and are not intended to limit or limit the scope of the present invention. Reveal.

The physical and chemical properties of magnesium hydroxide prepared from the juice were measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometer), XRD (X-ray Diffraction), Scanning Electron Microscope (SEM) and the like.

In order to examine the proper molar ratio (Mg: Na molar ratio) for preparing magnesium hydroxide from the juice, the reaction conditions were fixed at a dilution ratio of 1:10, agitation time 120 minutes, and a stirring rate of 300 rpm. Magnesium hydroxide was prepared by changing the ratio.

20 ml of the juice is added to the reactor, and the dilution ratio is adjusted to 10 times with distilled water to make a reactant. The diluted juice is turned well with a stirrer and mixed well and the initial pH is measured. A total of 20 ml of 1 M, 2 M, 3 M, and 5 M NaOH solutions prepared therein, each 5 ml per minute, is added and stirred at 300 rpm for 120 minutes. After the reaction, the pH was measured, placed in a pressure filter, and the supernatant and the precipitate were separated.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried for 100 to 12 hours to obtain magnesium hydroxide.

Table 1 below shows the pH change and magnesium hydroxide recovery according to the Mg: Na molar ratio.

As shown in Table 1, it can be seen that as the Mg: Na molar ratio increases, the recovery of magnesium hydroxide approaches the theoretical recovery. In particular, when the Mg: Na molar ratio was low, the pH was lower than 9.34 compared to the high recovery condition. As reported in the literature, the pH of Mg ions and NaOH, which is a precipitant, was smoothly reacted to produce magnesium hydroxide particles of 12 or more. Coincided with

In addition, when the Mg: Na molar ratio is 1: 1, Mg ions and OH ⁻ ions contained in the juice are predicted to interfere with binding to magnesium hydroxide by other impurities, and the production of the produced magnesium hydroxide particles is different. The dry weight of Mg (OH) ₂ recovered by filtration was estimated to be three times lower than the theoretical weight.

However, it can be seen that as the molar ratio increases, the pH is maintained at 12 to 13 and recovers more than 80% of the expected weight. This is consistent with the report that Mg ions contained in the juice are precipitated with magnesium hydroxide between pH 12-13 and affect the particles of magnesium hydroxide produced during precipitation.

However, the excess Mg: Na molar ratio increases the cost of recovering magnesium hydroxide, which affects the economics. Therefore, the future process parameters are fixed by fixing the Mg: Na molar ratio to 1: 3.

Table 1 below shows the pH change and magnesium hydroxide recovery according to the Mg: Na molar ratio.

Experimental conditions After precipitation
Solution volume (ml) pH Actual dry weight (g) before after Mg: Na = 1: 1 220 8.10 9.34 0.634 Mg: Na = 1: 2 220 8.10 11.99 1.314 Mg: Na = 1: 3 220 8.10 12.78 1.446 Mg: Na = 1: 5 220 8.10 13.12 1.712

Next, to determine the effect of the dilution ratio of the juice, the Mg: Na molar ratio was fixed at 1: 3, and then the agitation time was 120 minutes for the dilution ratio (1, 2, 5, 10, 20). The stirring speed was fixed at 300 rpm, and magnesium hydroxide was prepared by changing the molar ratio of NaOH, which is an alkaline substance, and magnesium hydroxide recovery and pH effects were measured.

20 ml of juice is added to the reactor and dilution with distilled or sea water is adjusted to 1, 2, 5, 10, 20 times to prepare a diluted juice juice. The diluted juice is turned well with a stirrer and mixed well and the initial pH is measured.

As shown in Example 1, after fixing the optimal Mg: Na molar ratio of 1: 3, a total of 20 ml of 5 mL / min of NaOH solution, which is an alkaline substance, was added and stirred at a speed of 300 rpm for 120 minutes. After the reaction, the pH was measured, placed in a pressure filter, and the supernatant and the precipitate were separated.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Table 2 below shows the pH change and magnesium hydroxide recovery according to the dilution ratio of the juice.

As shown in Table 2, when NaOH as a precipitant was supplied to the juice solution, the recovery rate of magnesium hydroxide was very low. When excess Mg ions were present in the juice, NaOH was dissolved in the high concentration solution when NaOH was added. Due to the influence on solubility, the number of collisions with Mg ions was low, and thus the reaction rate was reduced, indicating that magnesium hydroxide was lowered.

Therefore, the higher the dilution rate of the juice, the higher the magnesium hydroxide recovery rate, but when the high juice dilution ratio is high, there is a problem that a lot of process drainage used as the dilution water occurs. It can be seen that this is excellent.

Table 2 below shows the pH change and magnesium hydroxide recovery according to the dilution ratio of the juice.

Experimental conditions After precipitation
Solution volume (ml) pH real
Dry weight (g) before after Bittern crude 200 6.20 12.92 8.178 Bittern diluted 2times 120 7.32 12.98 4.028 Bittern diluted 5times 120 8.04 12.96 2.19 Bittern diluted 10times 220 8.10 12.78 1.446 Bittern diluted 20times 420 8.66 12.59 0.388

Next, in order to determine the effect of the stirring time, as shown in Examples 1 and 2, the dilution ratio of the juice having the optimum performance was 10 times, the stirring speed was 300 rpm, and the Mg: Na molar ratio was 1: 3. After fixation, the magnesium hydroxide recovery and pH influence were measured according to the stirring time.

20 ml of the juice is added to the reactor and the dilution ratio is adjusted to 10 times with distilled or sea water as shown in Example 2 to make the juice dilution reactant. The diluted juice is turned well with a stirrer and mixed well and the initial pH is measured. As shown in Example 1, after fixing the optimal Mg: Na molar ratio 1: 3, a total of 20ml of NaOH solution, 5 ml per minute, was added, respectively, and fixed at 30, 60, 90, 120, and 150 minutes at 300 rpm. Stir. After the reaction, the pH was measured, placed in a pressure filter, and the supernatant and the precipitate were separated.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Table 3 below shows the pH change and magnesium hydroxide recovery according to the stirring time.

As shown in Table 3, the magnesium hydroxide recovery was reduced from 0.886 g to 0.660 g until the stirring time was 90 minutes. Mg ions and OH ^- ions were physically combined up to 90 minutes when the precipitant was added to the magnesium hydroxide floc (nucleus). Although the formation temporarily increases, it is believed that the amount of magnesium hydroxide recovered decreases because the floc does not grow with the stirring time. After 90 minutes, the recovery rate increases because the magnesium hydroxide filtered as the floc grows increases.

Therefore, in the case of the stirring time, 120 minutes is a condition that can form a Mg (OH) ₂ floc separable by filtration, so a stirring time of at least 120 minutes or more is required during the process operation.

Table 3 below shows the pH change and magnesium hydroxide recovery according to the stirring time.

Experimental conditions After precipitation
Solution volume (ml) pH real
Dry weight (g) before after Bittern 30min Reaction 220 8.10 12.70 0.886 Bittern 60min Reaction 220 8.10 12.74 0.720 Bittern 90min Reaction 220 8.10 12.69 0.660 Bittern 120min Reaction 220 8.10 12.78 1.446 Bittern 150min Reaction 220 8.10 12.83 1.484

Next, to determine the effect of stirring speed, the dilution ratio of the high juice, which is the optimum condition shown in Examples 1 to 3, was fixed 10 times, the Mg: Na molar ratio of 1: 3, and the stirring time was 120 minutes, followed by the recovery of magnesium hydroxide. pH influence was measured.

First, 20 ml of juice is added to the reactor, and dilution ratio is adjusted to 10 times with distilled or sea water as shown in Example 2 to make a juice dilution reactant. The diluted juice is turned well with a stirrer and mixed well and the initial pH is measured. As shown in Example 1, after fixing the optimal Mg: Na molar ratio of 1: 3, a total of 20 ml of 5 mL / min of NaOH solution, which is an alkaline substance, was added. The stirring speed was 50 rpm, 100 rpm, 200 rpm, 300 rpm, 400 Experiment by adjusting to rpm, stirring by fixing the stirring time to 120 minutes as shown in Example 3. At this time, the pH was measured after the reaction, and put into a pressure filter to separate the supernatant and the precipitate.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Table 4 below shows the pH change and magnesium hydroxide recovery according to the stirring speed.

As shown in Table 4, as the stirring speed was increased, nucleation was increased, and the recovery rate of magnesium hydroxide was increased, and when the stirring speed was 400 rpm, magnesium hydroxide recovery and recovery were 1.839 g (theoretical recovery amount: 1.878 g) and 97.9. It was%. Therefore, as a result of experimenting on the effect of the stirring speed on the particles, a high stirring speed of 300 rpm or higher was applied to the NaOH introduced into the precipitant to be highly dispersed in the high juice of high density and viscosity and to promote the nuclear growth and to react with magnesium hydroxide. Know what you need.

Table 4 below shows the pH change and magnesium hydroxide recovery according to the stirring speed.

Experimental conditions After precipitation
Solution volume (ml) pH real
Dry weight (g) before after 50 rpm 220 8.10 12.72 1.059 100 rpm 220 8.10 12.73 1.268 200 rpm 220 8.10 12.79 1.435 300 rpm 220 8.10 12.78 1.446 400 rpm 220 8.10 12.76 1.839

Next, to determine the effect according to the reaction temperature, the dilution ratio of the juice, which is the optimum condition shown in Examples 1 to 4, was 10 times, the stirring speed was 300 rpm, and the Mg: Na molar ratio was fixed at 1: 3 and the stirring time was 120 minutes. Magnesium hydroxide recovery amount and filtration time were measured.

First, 20 ml of high juice is added to a temperature control reactor, and the dilution ratio is adjusted to 10 times with distilled or seawater to prepare a high juice dilution reactant. The diluted juice is mixed well by turning with a stirrer and the initial pH is measured. 3 ml of NaOH solution is added to 20 ml of 5 ml / min each, and stirred according to the reaction temperature conditions (40 ° C., 50 ° C., 70 ° C. and 80 ° C.). Stir for 120 minutes at a speed of 300 rpm.

At this time, the pH was measured after the reaction, and put into a pressure filter to separate the supernatant and the precipitate. At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Table 5 below shows the filtration time and magnesium hydroxide recovery according to the reaction temperature conditions.

As shown in Table 5, it can be seen that the magnesium hydroxide dry weight increases with increasing precipitation reaction temperature, and the filtration time is also shortened. The particle size decreases with increasing precipitation temperature, and the sedimentation rate gradually increases with increasing temperature, which follows Myers's theory of crystal growth. It is consistent with what is reported.

In addition, the filtration time of the precipitate according to the precipitation reaction temperature was found to be further shortened as the reaction temperature increases. This means that as the precipitation reaction temperature increases, the surface of the magnesium hydroxide particles produced by decreasing the flocculation effect of the precipitate during filtration changes in a direction favorable for filtration.

Table 5 below shows the filtration time and magnesium hydroxide recovery according to the reaction temperature conditions.

Experimental conditions After precipitation
Solution volume (ml) pH real
Dry weight (g) Filtration time (min) before after Room temperature 220 8.1 12.78 1.446 180-240 40 220 8.4 12.59 1.438 35 50 220 8.4 12.59 1.428 35 70 220 8.4 12.61 1.647 25 80 220 8.4 12.53 1.788 30

Next, the effect of magnesium hydroxide seed addition to increase the particle growth and filtration efficiency of magnesium hydroxide was measured.

In general, magnesium hydroxide obtained in the precipitation process is very fine particles that can cause many problems in the filtration process. In order to prevent such a problem and increase the efficiency of the filtration process, a magnesium hydroxide precipitate is prepared in advance, and the suspension is added to the juice to carry out seed addition to promote the growth of magnesium hydroxide particles.

First, 20 ml of the juice is added to the reactor, and the dilution ratio is adjusted to 10 times with distilled water to make a reactant. The diluted juice is turned well with a stirrer and mixed well and the initial pH is measured. 20 ml of 3 M NaOH solution prepared therein were added 5 ml / min each, and the mixture was stirred at 300 rpm for 120 minutes. In particular, in order to increase the particle size of magnesium hydroxide, magnesium hydroxide seed was added at the initial stage of stirring (2.5% by mass, 5% by mass, 15% by mass, 20% by mass) to react for 120 minutes, and then pH was measured. In a pressure filter, the supernatant and sediment are separated.

At this time, the precipitate separated as a solid may be manufactured with magnesium hydroxide, and filtered and washed with water or seawater to remove unreacted alkaline solution and impurities, thereby improving the purity of magnesium hydroxide. In general, the precipitate remaining in the filter paper was put in a drier and dried at 100 ° C. for about 12 hours to obtain magnesium hydroxide.

Table 6 below shows the filtration time and the magnesium hydroxide recovery amount according to the amount of magnesium hydroxide added.

As shown in Table 6, the dry weight of magnesium hydroxide was greatly increased, and the filtration time was also significantly shortened. Particularly, when magnesium hydroxide fine particles were added as a result of adding 5% by mass of seeds, the amount of recovered magnesium hydroxide was about 10% higher when added as a solid than when the solution was added as a solution. It can be seen that it is greatly shortened.

It can be seen that magnesium hydroxide fine particles are added to facilitate the filtration operation together with the promotion of particle generation from the nucleation of the added solution.

Therefore, the addition of magnesium hydroxide seed during the batch and continuous process plays a decisive role in the recovery and filtration time of magnesium hydroxide, which is an important issue that must be considered in the process design to produce magnesium hydroxide in the future with increased production and low cost. .

Table 6 below shows the filtration time and the magnesium hydroxide recovery amount according to the amount of seed addition of magnesium hydroxide.

Experimental conditions Solution volume after precipitation (ml) pH Estimated Mg (OH) ₂ Weight (g) real
Dry weight (g) (%) Filtration time
(minute) before after 2.5% 0.5ml
(Insert into solution) 220 9.27 13 1.925 2.18 (113.25) 7 0.045 g
(Injected with a solid sample) 220 8.82 13.10 1.923 2.15 (111.80) 8 5% 1ml 220 9.56 13.02 1.972 1.96 (99.39) 8 0.09g 220 9.09 13.07 1.968 2.17 (110.26) 8 10% 2ml 220 9.65 13.05 2.066 2.07 (100.26) 7.5 0.18 g 220 9.5 13 2.058 2.33 (113.22) 8 15% 3 ml 220 9.75 13.13 2.160 2.27 (105.09) 8

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

On the other hand, Figure 3 shows the result of measuring the effect of the filtration time according to the precipitation time by leaving the precipitation solution for a long time 120 minutes after the stirring time according to the embodiments of the present invention shown in the graph. In addition, Figure 4 shows the state of the supernatant after filtration according to the precipitation time according to the embodiments of the present invention described above. Through this, it can be seen that the longer the settling time, the more favorable the preparation of magnesium hydroxide. As a result, the shorter the precipitation time, the larger the particles of magnesium hydroxide formed to shorten the filtration time during filtration, and the longer the precipitation time, the lower the recovery rate of magnesium hydroxide because the formed magnesium hydroxide is decomposed into fine particles.

As described above, an optimal embodiment has been disclosed in the drawings and specification. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (13)

(a) mixing and diluting dilution water with a juice containing magnesium;
(b) mixing the alkaline solution with the diluted juice to form magnesium hydroxide particles;
(c) stirring the mixed mixture to grow magnesium hydroxide particles;
(d) adding a seed to the mixed solution;
(e) aging the mixed solution, separating the precipitate through filtration to obtain magnesium hydroxide; Including;
The alkaline solution of step (b) comprises sodium hydroxide,
The molar ratio (Mg: Na molar ratio) of the juice and the sodium hydroxide at the time of mixing is 1: 1 to 1: 5, the reaction temperature is 20 ° C. to 80 ° C. when mixing, and the mixing speed is within 10 minutes at 50 rpm to 100 rpm. Method for producing magnesium hydroxide, characterized in that the stirring.
The method of claim 1,
In the step (a)
The dilution water is water or sea water,
Magnesium hydroxide production method characterized in that the dilution by adding water or sea water in a volume ratio of 1: 1 to 1:20 relative to the juice.
delete delete The method of claim 1,
Magnesium hydroxide production method characterized in that the alkaline solution of step (b) comprises Ca (OH) ₂ or NH ₄ OH.
The method of claim 1,
In the step (c)
When stirring, the reaction temperature is 20 ℃ to 80 ℃, the stirring speed is magnesium hydroxide manufacturing method characterized in that the stirring for 10 to 150 minutes at 50 rpm to 500 rpm.
The method of claim 1,
The seed of step (d) comprises magnesium hydroxide,
Magnesium hydroxide manufacturing method characterized in that the addition of 2.5% by mass to 15% by mass of magnesium hydroxide compared to the concentration of magnesium contained in the mixture.
The method of claim 1,
In the step (e)
Magnesium hydroxide production method characterized in that the reaction temperature is 20 ℃ to 80 ℃ during aging, the stirring speed is stirred for 10 to 150 minutes at 100 rpm to 500 rpm.
The method of claim 1,
After the step (e)
Magnesium hydroxide production method characterized by washing the magnesium hydroxide of the precipitate using water or sea water.
The method of claim 9,
A method for producing magnesium hydroxide, characterized by drying magnesium hydroxide of the washed precipitate.
The method of claim 10,
Magnesium hydroxide production method characterized by firing the washed and dried magnesium hydroxide at 300 ℃ to 1000 ℃ to produce magnesium oxide.
The method of claim 9,
Wastewater collected after the washing is magnesium hydroxide manufacturing method, characterized in that recycled to the dilution water of the dilution step.
The method according to any one of claims 1, 2 and 5 to 12,
Wastewater collected after the filtration is magnesium hydroxide manufacturing method, characterized in that recycled to the dilution water of the dilution step.

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