Magnesium hydroxide slurry and manufacturing method thereof

Abstract

The present invention provides a magnesium hydroxide slurry comprising a first dispersant, a second dispersant, Mg(OH)2 and the balance of water, wherein the amount of Mg(OH)2 is 50 wt% or more relative to 100 wt% of the total slurry, the amount of the first dispersant is in the range of 0.5-2 wt% relative to 100 wt% of the total Mg(OH)2, the amount of the second dispersant is in the range of 0.03-0.1 wt% relative to 100 wt% of the total Mg(OH)2, and the hydrophilic lipophilic balance (HLB) values of the first dispersant and the second dispersant independently satisfy the range of 8-20.

Description

Magnesium hydroxide slurry and method for manufacturing the same

[0001] The present invention relates to a magnesium hydroxide slurry, and specifically to a method for producing a magnesium hydroxide slurry from seawater.

[0002] The present invention claims priority to Korean Patent Application No. 10-2024-0150754 filed on October 30, 2024, the entire contents of said prior application incorporated herein by reference.

[0003] Magnesium hydroxide slurry is widely applied in various fields, including industrial sectors such as pharmaceuticals, food additives, flame retardants, and gas desulfurization, as well as environmentally friendly applications such as wastewater treatment.

[0004] Natural magnesium hydroxide slurry is prepared through a hydration reaction with magnesium oxide and the particle size is adjusted by wet grinding. Considering viscosity and storage stability, this natural magnesium hydroxide slurry is prepared by adding approximately 2.5 wt% of a dispersant based on the solid content.

[0005] On the other hand, synthetic magnesium hydroxide slurry is produced by reacting Mg ions present in seawater with an alkaline precipitating agent through an ion exchange chemical reaction, and unlike the production of natural magnesium hydroxide slurry, a coagulant is added to facilitate the dehydration reaction. Consequently, compared to natural magnesium hydroxide slurry, synthetic magnesium hydroxide slurry suffers from problems such as a rapid increase in viscosity and hardening of precipitates when a dispersant is added. This impairs fluidity and storage stability, which currently acts as an obstacle to the commercialization of synthetic magnesium hydroxide slurry.

[0006] In addition, magnesium hydroxide slurries are classified into low concentration and high concentration depending on the concentration of Mg(OH)2 contained therein; however, high concentration magnesium hydroxide slurries tend to lose fluidity easily, which leads to the aforementioned problems.

[0007] Accordingly, the present invention aims to provide a synthetic magnesium hydroxide slurry and a method for manufacturing the same, which solves the aforementioned problems and secures the fluidity and storage stability of the natural magnesium hydroxide slurry.

[0008] The objective of the present invention is to provide a magnesium hydroxide slurry with high fluidity and storage stability and reduced hardening of precipitates.

[0009] Another objective of the present invention is to provide a method for manufacturing a magnesium hydroxide slurry that has the aforementioned advantages and ensures productivity and economic efficiency.

[0010] A magnesium hydroxide slurry according to one embodiment of the present invention comprises a first dispersant, a second dispersant, Mg(OH)2, and the remainder being water, wherein the content of Mg(OH)2 is 50 wt% or more with respect to 100 wt% of the total slurry, the content of the first dispersant is in the range of 0.5 to 2 wt% with respect to 100 wt% of the total Mg(OH)2, the content of the second dispersant is in the range of 0.03 to 0.1 wt% with respect to 100 wt% of the total Mg(OH)2, and the HLB (Hydrophilic lipophilic balance) values ​​of the first dispersant and the second dispersant independently satisfy the range of 8 to 20.

[0011] The HLB value of the first dispersant may be in the range of 8 to 15.

[0012] The HLB value of the second dispersant may be in the range of 12 to 18.

[0013] The magnesium hydroxide slurry may further include a coagulant, and the content of the coagulant may be greater than 0 and less than or equal to 800 ppm with respect to the slurry.

[0014] The magnesium hydroxide slurry above may satisfy at least one of the following formulas 1 to 3.

[0015] [Equation 1]

[0016] 1 ≤ P3 / P1 ≤ 6

[0017] [Equation 2]

[0018] 2 ≤ P4 / P1 < 40

[0019] [Equation 3]

[0020] 1 ≤ P3 / P2 ≤ 1.8

[0021] (In the above formulas 1 to 3, the above P n ... refers to the viscosity of the magnesium hydroxide slurry at the time point n of storage.)

[0022] The above P4 may be in the range of 200 to 1000 cp.

[0023] The first dispersant may include at least one of organic acids, polycarboxylates, polyacrylates, polyacrylate copolymers, acrylics, salts thereof, lignosulfonates, polyethylene glycol, polyacrylamide, pyrobosate, sodium citrate, and ammonium citrate.

[0024] The second dispersant is a phosphate-based material and may include at least one of sodium monophosphate, sodium disphosphate, sodium triphosphate, potassium monophosphate, potassium disphosphate, potassium triphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, sodium acid pyrophosphate, sodium hexametaphosphate, and sodium metaphosphate.

[0025] A method for preparing a magnesium hydroxide slurry according to another embodiment of the present invention comprises: (S1) a step of forming a low-concentration slurry by adding a coagulant to seawater; (S2) a step of preparing a high-concentration slurry containing 50 wt% or more of Mg(OH)2 with respect to 100 wt% of the total by filtering the low-concentration slurry with a centrifugal dewatering machine; and (S3) a step of adjusting the concentration by simultaneously adding the high-concentration slurry, a first dispersant, a second dispersant, and water to a stirrer; wherein steps (S2) and (S3) are performed continuously.

[0026] In step (S1) above, the coagulant can be added to the high-concentration slurry at a concentration of 800 ppm or less.

[0027] In step (S1) above, the coagulant may include a cationic polymer compound.

[0028] The above cationic polymer compound may include at least one of polyacrylamide, polyethyleneamine, polydiallyldimethylammonium chloride, polyamine, epichlorohydrin, and diethylenetriamine.

[0029] In step (S3) above, the HLB (Hydrophilic lipophilic balance) values ​​of the first dispersant and the second dispersant may be in the range of 8 to 20 independently of each other.

[0030] The HLB value of the first dispersant may be in the range of 8 to 15.

[0031] The HLB value of the second dispersant may be in the range of 12 to 18.

[0032] A magnesium hydroxide slurry according to one embodiment of the present invention can solve the aforementioned problems by simultaneously adding a first dispersant and a second dispersant having different HLB (Hydrophilic lipophilic balance), thereby increasing fluidity and storage stability and reducing the hardening of precipitates.

[0033] A method for manufacturing a magnesium hydroxide slurry according to another embodiment of the present invention can produce a magnesium hydroxide slurry having the aforementioned advantages while ensuring productivity and economic efficiency through a centrifugal dehydrator and a continuous process.

[0034] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0035] When it is stated that one part is "above" or "on" another part, it may be directly above or on the other part, or other parts may be involved in between. In contrast, when it is stated that one part is "directly above" another part, no other parts are interposed in between.

[0036] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0037] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0038]

[0039] magnesium hydroxide slurry

[0040] In one embodiment of the present invention, a magnesium hydroxide slurry is provided that solves the aforementioned problems by adding a first dispersant and a second dispersant having different HLB (Hydrophilic lipophilic balance), thereby having high fluidity and storage stability and reduced hardening of the precipitate.

[0041] In one embodiment, the magnesium hydroxide slurry comprises a first dispersant, a second dispersant, Mg(OH)2, and the remainder being water, wherein the content of Mg(OH)2 is 50 wt% or more with respect to 100 wt% of the total slurry, the content of the first dispersant is in the range of 0.5 to 2 wt% with respect to 100 wt% of the total Mg(OH)2, the content of the second dispersant is in the range of 0.03 to 0.1 wt% with respect to 100 wt% of the total Mg(OH)2, and the Hydrophlic Lipophilic Balance (HLB) values ​​of the first dispersant and the second dispersant can independently satisfy a range of 8 to 20.

[0042] The above HLB is a numerical representation of the degree of hydrophilicity and lipophilicity of the dispersant. HLB starts at 1 for the highest lipophilicity, and widely used dispersants generally have an HLB between 1 and 20.

[0043] The HLB values ​​of the first dispersant and the second dispersant can independently satisfy a range of 8 to 20. Specifically, 8 to 19, 8 to 18, 8 to 17, 8 to 16, 8 to 15, 8 to 14, 8 to 13, 9 to 20, 9 to 19, 9 to 18, 9 to 17, 9 to 16, 9 to 15, 9 to 14, 9 to 13, 10 to 20, 10 to 19, 10 to 18, 10 to 17, 10 to 16, 10 to 15, 10 to 14, 10 to 13, 11 to 20, 11 to 19, 11 to 18, 11 to 17, 11 to 16, 11 to 15, 11 to 14, 11 to 13, 12 to 20, 12 It may be up to 19, 12 to 18, 12 to 17, 12 to 16, 12 to 15, 12 to 14, or 12 to 13.

[0044] By satisfying the aforementioned range of the HLB value, the fluidity and storage stability of the magnesium hydroxide slurry can be secured, and the hardening of precipitates can be effectively prevented. If the HLB value deviates from the upper limit of the aforementioned range, there are problems such as increased costs due to the dispersant, difficulties in supply, and unsuitability for the manufacture of magnesium hydroxide slurry. Furthermore, if it deviates from the lower limit of the aforementioned range, there are problems such as the inability to secure the aforementioned advantages.

[0045] The magnesium hydroxide slurry contains 50 wt% or more of the Mg(OH)2 with respect to 100 wt% of the total, and may contain the remainder being water. Specifically, it may contain 51 wt% or more, 52 wt% or more, 53 wt% or more, 54 wt% or more, 55 wt% or more, 56 wt% or more, 57 wt% or more, 58 wt% or more, 59 wt% or more, 60 wt% or more, 61 wt% or more, 62 wt% or more, 63 wt% or more, 64 wt% or more, 65 wt% or more, 66 wt% or more, 67 wt% or more, and the remainder being water.

[0046] By satisfying the aforementioned range of Mg(OH)2 content, the magnesium hydroxide slurry contains Mg(OH)2 at a high concentration and can be effectively used in various industrial fields. If the Mg(OH)2 content falls outside the lower limit of the aforementioned range, it corresponds to a low concentration and cannot exhibit the aforementioned advantages. Furthermore, the Mg(OH)2 content cannot reach 100 wt%, as this hinders the securing of fluidity and storage stability of the magnesium hydroxide slurry.

[0047] The content of the first dispersant above can satisfy a range of 0.5 to 2 wt% with respect to 100 wt% of the total Mg(OH)2. Specifically, 0.5 to 1.9 wt%, 0.5 to 1.8 wt%, 0.5 to 1.7 wt%, 0.5 to 1.6 wt%, 0.5 to 1.5 wt%, 0.5 to 1.4 wt%, 0.5 to 1.3 wt%, 0.5 to 1.2 wt%, 0.5 to 1.1 wt%, 0.5 to 1 wt%, 0.5 to 0.9 wt%, 0.5 to 0.8 wt%, 0.55 to 2 wt%, 0.55 to 1.9 wt%, 0.55 to 1.8 wt%, 0.55 to 1.7 wt%, 0.55 to 1.6 wt%, 0.55 to 1.5 wt%, 0.55 to 1.4 wt%, 0.55 to 1.3 wt%, 0.55 to 1.2 wt%, 0.55 to 1.1 wt%, 0.55 to 1 wt%, 0.55 to 0.9 wt%, 0.55 to 0.8 wt%, 0.6 to 2 wt%, 0.6 to 1.9 wt%, 0.6 to 1.8 wt%, 0.6 to 1.7 wt%, 0.6 to 1.6 wt%, 0.6 to 1.5 wt%, 0.6 to 1.4 wt%, 0.6 to 1.3 wt%, 0.6 to 1.2 wt%, 0.6 to 1.1 wt%, 0.6 to 1 wt%, 0.6 to 0.9 wt%, 0.6 to 0.8 wt%, 0.65 to 2 wt%, 0.65 to 1.9 wt%, 0.65 to 1.8 wt%, 0.65 to 1.7 wt%, 0.65 to 1.6 wt%, 0.65 to 1.5 wt%, 0.65 to 1.4 wt%, 0.65 to 1.3 wt%, 0.65 to 1.2 wt%, 0.65 to 1.1 wt%, 0.65 to 1 wt%, 0.65 to 0.9 wt%, 0.65 to 0.8 wt%, 0.7 to 2 wt%, 0.7 to 1.9 wt%, 0.7 to 1.8 wt%, 0.7 to 1.7 wt%, 0.7 to 1.6 wt%, 0.7 to 1.5 wt%, 0.It may be 7 to 1.4 wt%, 0.7 to 1.3 wt%, 0.7 to 1.2 wt%, 0.7 to 1.1 wt%, 0.7 to 1 wt%, 0.7 to 0.9 wt%, or 0.7 to 0.8 wt%.

[0048] By satisfying the aforementioned range for the content of the first dispersant, economic feasibility can be secured by using a smaller amount of dispersant compared to the preparation of natural magnesium hydroxide slurry. If the content of the first dispersant deviates from the upper limit of the aforementioned range, economic feasibility decreases and there is a problem of precipitate hardening occurring in the magnesium hydroxide slurry. In addition, if the content of the first dispersant deviates from the lower limit of the aforementioned range, it cannot perform its function as a dispersant, which may hinder the securing of fluidity and storability of the magnesium hydroxide slurry.

[0049] The content of the second dispersant above can satisfy a range of 0.03 to 0.1 wt% with respect to the total 100 wt% of Mg(OH)2. Specifically, 0.03 to 0.095 wt%, 0.03 to 0.09 wt%, 0.03 to 0.085 wt%, 0.03 to 0.08 wt%, 0.03 to 0.075 wt%, 0.03 to 0.07 wt%, 0.03 to 0.065 wt%, 0.03 to 0.06 wt%, 0.03 to 0.055 wt%, 0.03 to 0.1 wt%, 0.03 to 0.095 wt%, 0.03 to 0.09 wt%, 0.03 to 0.085 wt%, 0.03 to 0.08 wt%, 0.03 to 0.075 wt%, 0.03 to 0.07 wt%, 0.03 to 0.065 wt%, 0.03 to 0.06 wt%, 0.03 to 0.055 wt%, 0.035 to 0.1 wt%, 0.035 to 0.095 wt%, 0.035 to 0.09 wt%, 0.035 to 0.085 wt%, 0.035 to 0.08 wt%, 0.035 to 0.075 wt%, 0.035 to 0.07 wt%, 0.035 to 0.065 wt%, 0.035 to 0.06 wt%, 0.035 to 0.055 wt%, 0.04 to 0.1 wt%, 0.04 to 0.095 wt%, 0.04 to 0.09 wt%, 0.04 to 0.085 wt%, 0.04 to 0.08 wt%, 0.04 to 0.075 wt%, 0.04 to 0.07 wt%, 0.04 to 0.065 wt%, 0.04 to 0.06 wt%, 0.04 to 0.055 wt%, 0.045 to 0.1 wt%, 0.045 to 0.095 wt%, 0.045 to 0.09 wt%, 0.045 to 0.085 wt%, 0.045 to 0.08 wt%, 0.045 to 0.075 wt%, 0.045 to 0.07 wt%, 0.045 to 0.065 wt%, 0.045 to 0.06 wt%, 0.045 to 0.It may be 0.55 wt%, 0.05 to 0.1 wt%, 0.05 to 0.095 wt%, 0.05 to 0.09 wt%, 0.05 to 0.085 wt%, 0.05 to 0.08 wt%, 0.05 to 0.075 wt%, 0.05 to 0.07 wt%, 0.05 to 0.065 wt%, 0.05 to 0.06 wt%, 0.05 to 0.055 wt%.

[0050] By satisfying the aforementioned range for the content of the second dispersant, economic feasibility can be secured by using a smaller amount of dispersant compared to the preparation of natural magnesium hydroxide slurry. If the content of the second dispersant deviates from the upper limit of the aforementioned range, economic feasibility decreases and there is a problem of precipitate hardening occurring in the magnesium hydroxide slurry. In addition, if the content of the second dispersant deviates from the lower limit of the aforementioned range, it cannot perform its function as a dispersant, which may hinder the securing of fluidity and storability of the magnesium hydroxide slurry.

[0051] By including the first and second dispersants together in the magnesium hydroxide slurry, satisfying the content of the aforementioned ranges, the effect of securing fluidity and storage stability compared to the existing magnesium hydroxide slurry, preventing the hardening of precipitates, and securing economic efficiency is achieved.

[0052] In one embodiment, the HLB value of the first dispersant may satisfy the range of 8 to 15. Specifically, it may be 8 to 14, 8 to 13, 8 to 12, 9 to 15, 9 to 14, 9 to 13, 9 to 12, 10 to 15, 10 to 14, 10 to 13, 10 to 12, 11 to 15, 11 to 14, 11 to 13, 11 to 12.

[0053] By satisfying the aforementioned range for the HLB value of the first dispersant, the fluidity and storage stability of magnesium hydroxide can be secured, and the hardening of precipitates can be effectively prevented. If the HLB value deviates from the upper limit of the aforementioned range, there are problems such as increased costs due to the dispersant, difficulties in supply, and unsuitability for use in manufacturing magnesium hydroxide slurries. Furthermore, if it deviates from the lower limit of the aforementioned range, there are problems such as the inability to secure the aforementioned advantages.

[0054] In one embodiment, the HLB value of the second dispersant may satisfy the range of 12 to 18. Specifically, it may be 12 to 17, 12 to 16, 12 to 15, 13 to 18, 13 to 17, 13 to 16, 13 to 15, 14 to 18, 14 to 17, 14 to 16, or 14 to 15.

[0055] By satisfying the aforementioned range for the HLB value of the second dispersant, the fluidity and storage stability of magnesium hydroxide can be secured, and the hardening of precipitates can be effectively prevented. If the HLB value deviates from the upper limit of the aforementioned range, there are problems such as increased costs due to the dispersant, difficulties in supply, and unsuitability for use in manufacturing magnesium hydroxide slurries. Furthermore, if it deviates from the lower limit of the aforementioned range, there are problems such as the inability to secure the aforementioned advantages.

[0056] In one embodiment, the slurry may further include a coagulant, and the content of the coagulant may be greater than 0 and less than or equal to 800 ppm with respect to the slurry. The coagulant enables obtaining Mg(OH)2 from seawater at a high concentration.

[0057] Specifically, greater than 0 and less than or equal to 750 ppm, greater than 0 and less than or equal to 700 ppm, greater than 0 and less than or equal to 650 ppm, greater than 0 and less than or equal to 600 ppm, greater than 0 and less than or equal to 550 ppm, 50 to 800 ppm, 50 to 750 ppm, 50 to 700 ppm, 50 to 650 ppm, 50 to 600 ppm, 50 to 550 ppm, 100 to 800 ppm, 100 to 750 ppm, 100 to 700 ppm, 100 to 650 ppm, 100 to 600 ppm, 100 to 550 ppm, 150 to 800 ppm, 150 to 750 ppm, 150 to 700 ppm, 150 to 650 ppm, It may be 150 to 600 ppm, 150 to 550 ppm, 200 to 800 ppm, 200 to 750 ppm, 200 to 700 ppm, 200 to 650 ppm, 200 to 600 ppm, 200 to 550 ppm, 250 to 800 ppm, 250 to 750 ppm, 250 to 700 ppm, 250 to 650 ppm, 250 to 600 ppm, or 250 to 550 ppm.

[0058] By satisfying the aforementioned range of the coagulant content, the dehydration reaction of the synthetic magnesium hydroxide slurry can be facilitated and the hardening of the precipitate can be prevented. If the content of the coagulant exceeds the upper limit of the aforementioned range, the amount of dispersant added also increases, which is disadvantageous in terms of cost, impairs fluidity and storage stability, and causes the hardening of the precipitate. Furthermore, if the content of the coagulant exceeds the lower limit of the aforementioned range, there is a problem in that the aforementioned advantages cannot be achieved.

[0059] The above-mentioned coagulant may include a cationic polymer compound. Specifically, the cationic polymer compound may be at least one of polyacrylamide, polyethyleneamine, polydiallyldimethylammonium chloride, polyamine, epichlorohydrin, and diethylenetriamine. However, the type of alkaline precipitating agent is not limited thereto and can be modified by the common sense of those skilled in the art as long as it performs the aforementioned function and does not impair the purpose of the present invention.

[0060] In one embodiment, the magnesium hydroxide slurry may satisfy at least one of the following formulas 1 to 3.

[0061] [Equation 1]

[0062] 1 ≤ P3 / P1 ≤ 6

[0063] [Equation 2]

[0064] 2 ≤ P4 / P1 < 40

[0065] [Equation 3]

[0066] 1 ≤ P3 / P2 ≤ 1.8

[0067] In the above Equations 1 to 3, the P n ... refers to the viscosity at the nth day of storage of the magnesium hydroxide slurry.

[0068] The above Equations 1 to 3 represent the ratio of viscosity at the time point n of storage of the magnesium hydroxide slurry, and can serve as an indicator of the fluidity, storage stability, and precipitate hardening of the magnesium hydroxide slurry. In this case, n can be 1 to 10.

[0069] The above Equation 1 can satisfy the range of 1 to 6. Specifically, 1 to 5.5, 1 to 5, 1 to 4.5, 1 to 4, 1 to 3.5, 1 to 3, 1 to 2.5, 1.2 to 6, 1.2 to 5, 1.2 to 4.5, 1.2 to 4, 1.2 to 3.5, 1.2 to 3, 1.2 to 2.5, 1.4 to 6, 1.4 to 5, 1.4 to 4.5, 1.4 to 4, 1.4 to 3.5, 1.4 to 3, 1.4 to 2.5, 1.6 to 6, 1.6 to 5, 1.6 to 4.5, 1.6 to 4, 1.6 to 3.5, 1.6 to 3, 1.6 to 2.5, 1.8 to 6, 1.8 to 5, 1.8 to 4.5, 1.8 to 4, 1.8 to 3.5, 1.8 to 3, 1.8 to 2.5, 2 to 6, 2 to 5, 2 to 4.5, 2 to 4, 2 to 3.5, 2 to 3, 2 to 2.5, 2.1 to 6, 2.1 to 5, 2.1 to 4.5, 2.1 to 4, 2.1 to 3.5, 2.1 to 3, 2.1 to 2.5, 2.2 to 6, 2.2 to 5, 2.2 to 4.5, 2.2 to 4, 2.2 to 3.5, 2.2 to 3, 2.2 to 2.5, 2.3 to 6, 2.3 to 5, 2.3 It may be up to 4.5, 2.3 to 4, 2.3 to 3.5, 2.3 to 3, 2.3 to 2.5, 2.4 to 6, 2.4 to 5, 2.4 to 4.5, 2.4 to 4, 2.4 to 3.5, 2.4 to 3, 2.4 to 2.5.

[0070] The above Equation 2 can satisfy the range of 2 to less than 40. Specifically, 2 to 35, 2 to 30, 2 to 25, 2 to 20, 2 to 15, 2 to 13, 2 to 12, 2 to 11, 2 to 10, 2 to 9.5, 2 to 9, less than 2.5 to 40, 2.5 to 35, 2.5 to 30, 2.5 to 25, 2.5 to 20, 2.5 to 15, 2.5 to 13, 2.5 to 12, 2.5 to 11, 2.5 to 10, 2.5 to 9.5, 2.5 to 9, less than 3 to 40, 3 to 35, 3 to 30, 3 to 25, 3 to 20, 3 to 15, 3 to 13, 3 to 12, 3 to 11, 3 to 10, 3 to 9.5, 3 to 9, 3.5 to less than 40, 3.5 to 35, 3.5 to 30, 3.5 to 25, 3.5 to 20, 3.5 to 15, 3.5 to 13, 3.5 to 12, 3.5 to 11, 3.5 to 10, 3.5 to 9.5, 3.5 to 9, 4 to less than 40, 4 to 35, 4 to 30, 4 to 25, 4 to 20, 4 to 15, 4 to 13, 4 to 12, 4 to 11, 4 to 10, 4 to 9.5, 4 to 9, 4.5 to less than 40, 4.5 to 35, 4.5 to 30, 4.5 to 25, 4.5 to 20, 4.5 to 15, 4.5 to 13, 4.5 to 12, 4.5 to 11, 4.5 to 10, 4.5 to 9.5, 4.5 to 9, less than 2.5 to 40, 5 to 35, 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 13, 5 to 12, 5 to 11, 5 to 10, 5 to 9.5, 5 to 9, less than 5.5 to 40, 5.5 to 35, 5.5 to 30, 5.5 to 25, 5.5 to 20, 5.5 to 15, 5.5 to 13, 5.5 to 12, 5.5 to 11, 5.5 to 10, 5.5 to 9.It may be 5, 5.5 to 9, 6 to less than 40, 6 to 35, 6 to 30, 6 to 25, 6 to 20, 6 to 15, 6 to 13, 6 to 12, 6 to 11, 6 to 10, 6 to 9.5, 6 to 9, 6.5 to less than 40, 6.5 to 35, 6.5 to 30, 6.5 to 25, 6.5 to 20, 6.5 to 15, 6.5 to 13, 6.5 to 12, 6.5 to 11, 6.5 to 10, 6.5 to 9.5, 6.5 to 9.

[0071] The above Equation 3 can satisfy the range of 1 to 1.8. Specifically, 1 to 1.7, 1 to 1.6, 1 to 1.5, 1 to 1.4, 1 to 1.3, 1 to 1.2, 1 to 1.15, 1 to 1.1, 1 to 1.08, 1.01 to 1.8, 1.01 to 1.7, 1.01 to 1.6, 1.01 to 1.5, 1.01 to 1.4, 1.01 to 1.3, 1.01 to 1.2, 1.01 to 1.15, 1.01 to 1.1, 1.01 to 1.08, 1.02 to 1.8, 1.02 to 1.7, 1.02 to 1.6, 1.02 to 1.5, 1.02 to 1.4, 1.02 to 1.3, 1.02 to 1.2, 1.02 to 1.15, 1.02 to 1.1, 1.02 to 1.08, 1.03 to 1.8, 1.03 to 1.7, 1.03 to 1.6, 1.03 to 1.5, 1.03 to 1.4, 1.03 to 1.3, 1.03 to 1.2, 1.03 to 1.15, 1.03 to 1.1, 1.03 to 1.08, 1.04 to 1.8, 1.04 to 1.7, 1.04 to 1.6, 1.04 to 1.5, 1.04 to 1.4, 1.04 to 1.3, 1.04 to 1.2, It may be 1.04 to 1.15, 1.04 to 1.1, 1.04 to 1.08, 1.05 to 1.8, 1.05 to 1.7, 1.05 to 1.6, 1.05 to 1.5, 1.05 to 1.4, 1.05 to 1.3, 1.05 to 1.2, 1.05 to 1.15, 1.05 to 1.1, 1.05 to 1.08.

[0072] By satisfying the aforementioned ranges of Equations 1 to 3, the magnesium hydroxide slurry can secure fluidity and storage stability and prevent precipitate hardening. If Equations 1 to 3 fall outside the upper limit of the aforementioned range, the aforementioned advantages cannot be satisfied, which presents a problem that makes it difficult to use in industrial fields. Additionally, while cases where Equations 1 to 3 fall outside the lower limit of the aforementioned range may exist, this presents a problem where the cationic coagulant and anionic dispersant contained in the synthetic magnesium hydroxide react to create an atmosphere of charge instability in the slurry, causing a temporary increase in viscosity. However, research on synthetic magnesium hydroxide that falls outside the lower limit is currently insufficient. Furthermore, in the case of Equation 3, since the viscosity on the third day cannot be lower than the viscosity on the second day, the theoretical lower limit cannot be less than 1.

[0073] In one embodiment, P1 may be in the range of greater than 0 and less than 200 cp. Specifically, it may be greater than 0 and less than 180 cp, greater than 0 and less than 160 cp, greater than 0 and less than 140 cp, less than 20 to 200 cp, 20 to 180 cp, 20 to 160 cp, 20 to 140 cp, less than 40 to 200 cp, 40 to 180 cp, 40 to 160 cp, 40 to 140 cp, less than 60 to 200 cp, 60 to 180 cp, 60 to 160 cp, 60 to 140 cp, less than 80 to 200 cp, 80 to 180 cp, 80 to 160 cp, and 80 to 140 cp.

[0074] Since P1 represents the viscosity of the magnesium hydroxide slurry on the first day of storage, the aforementioned range must be satisfied to ensure fluidity and storage stability. If the value falls outside the upper limit of the aforementioned range, there is a problem where storage stability is significantly reduced because the product must be used immediately after manufacturing. Furthermore, if the value falls outside the lower limit, it is theoretically difficult to reach.

[0075] As with P1 above, P2, P3, and P4 included in at least one of Equations 1 to 3 are each viscosities of the magnesium hydroxide slurry on days 2, 3, and 4 of storage, respectively, and thus each have a value greater than the viscosity corresponding to the previous day. In this case, P4, which is the viscosity on day 4 of storage, can satisfy the range of 200 to 1000 cp. Specifically, it may be 200 to 900 cp, 200 to 850 cp, 200 to 800 cp, 200 to 750 cp, 250 to 1000 cp, 250 to 900 cp, 250 to 850 cp, 250 to 800 cp, 250 to 750 cp, 300 to 1000 cp, 300 to 900 cp, 300 to 850 cp, 300 to 800 cp, 300 to 750 cp, 350 to 1000 cp, 350 to 900 cp, 350 to 850 cp, 350 to 800 cp, 350 to 750 cp.

[0076] By satisfying the aforementioned range of P4, the fluidity and storage stability of the magnesium hydroxide slurry can be secured, and it can have characteristics similar to natural magnesium hydroxide slurry. If the value falls outside the upper limit of the aforementioned range, the aforementioned advantages cannot be obtained, and there is a problem of precipitate hardening.

[0077] In one embodiment, the first dispersant may include at least one of organic acids, polycarboxylates, polyacrylates, polyacrylate copolymers, acrylics, salts thereof, lignosulfonates, polyethylene glycol, polyacrylamide, pyrobosate, sodium citrate, and ammonium citrate. However, it is not limited thereto, and any material that satisfies the aforementioned HLB range can be modified by the common sense of a person skilled in the art without compromising the purpose of the present invention.

[0078] In one embodiment, the second dispersant is a phosphate-based material and may include at least one of sodium monophosphate, sodium disphosphate, sodium triphosphate, potassium monophosphate, potassium disphosphate, potassium triphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, sodium acid pyrophosphate, sodium hexametaphosphate, and sodium metaphosphate. By including the aforementioned second dispersant together with the first dispersant, the magnesium hydroxide slurry can prevent precipitates in the slurry from hardening or viscosity from rapidly increasing due to the cationic coagulant. However, the material of the second dispersant is not limited thereto, and any material that is anionic and satisfies the aforementioned HLB range may be modified by the common sense of a person skilled in the art without compromising the purpose of the present invention.

[0079]

[0080] Method for preparing magnesium hydroxide slurry

[0081] In another embodiment of the present invention, a method for manufacturing a magnesium hydroxide slurry having the aforementioned advantages is provided, which ensures productivity and economic efficiency through a centrifugal dehydrator and a continuous process.

[0082] In one embodiment, the method for preparing the magnesium hydroxide slurry comprises: (S1) a step of forming a low-concentration slurry by adding a coagulant to seawater; (S2) a step of preparing a high-concentration slurry containing 50 wt% or more of Mg(OH)2 relative to 100 wt% of the total by filtering the low-concentration slurry with a centrifugal dewatering machine; and (S3) a step of adjusting the concentration by simultaneously adding the high-concentration slurry, a first dispersant, a second dispersant, and water to a stirrer; wherein steps (S2) and (S3) can be performed continuously.

[0083] The above step (S2) involves a process of filtering the high-concentration slurry using the centrifugal dewatering machine, which reduces costs compared to filtration devices such as filter presses used in concentration processes in the industry and enables a continuous process, thereby ensuring productivity.

[0084] The above method for manufacturing the magnesium hydroxide slurry can reduce costs and secure productivity compared to existing processes using batch reactors in the industry by ensuring that steps (S2) and (S3) proceed continuously. Specifically, it is expected that a high-concentration slurry containing 50 wt% or more of Mg(OH)2 relative to the total 100 wt% can be produced at a rate of 50 tons / day or more, and has the advantage of being automatable.

[0085] In one embodiment, in step (S1), the coagulant may be added to the high-concentration slurry at a concentration of 800 ppm or less.

[0086] In one embodiment, the coagulant in step (S1) may include a cationic polymer compound. Further description of the coagulant can be found in the section regarding the magnesium hydroxide slurry described above.

[0087] In one embodiment, in step (S3), the HLB (Hydrophilic lipophilic balance) values ​​of the first dispersant and the second dispersant may be independently in the range of 8 to 20. Additionally, the HLB value of the first dispersant may be in the range of 8 to 15, and the HLB value of the second dispersant may be in the range of 12 to 16. Further description of the first dispersant and the second dispersant can be referenced in the section regarding the magnesium hydroxide slurry described above.

[0088] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0089]

[0090] Example: Synthetic magnesium hydroxide slurry

[0091] Ca(OH)2 was added to seawater to form Mg(OH)2 through an ion exchange chemical reaction. At this time, to facilitate the reaction and obtain a high concentration of Mg(OH)2, polyacrylamide was added as a coagulant at a concentration of 600 ppm or less. Subsequently, the mixture was filtered using a centrifugal dehydrator to form a high-concentration slurry containing 50 wt% or more of Mg(OH)2 relative to 100 wt% of the total, while simultaneously adding polyacrylic acid, Na3PO4, and water to adjust the concentration. In this case, the polyacrylic acid content was 0.7 wt% relative to 100 wt% of the total Mg(OH)2, and the Na3PO4 content was 0.05 wt% relative to 100 wt% of the total Mg(OH)2 to prepare the example. The HLB value of polyacrylic acid is 10, and the HLB value of Na3PO4 is 13.

[0092]

[0093] Comparative Example: Synthetic magnesium hydroxide slurry

[0094] Comparative examples were prepared using the same manufacturing method as the examples, but with different types, content, and inclusion of at least one of the first and second dispersants. The types and compositions are as shown in Table 1 below. In this case, the content of the first and second dispersants corresponds to wt% of the total 100 wt% of Mg(OH)2.

[0095] Item Polyacrylic Acid Content (wt%) Second Dispersant Material Second Dispersant Content (wt%) Second Dispersant HLB Value Comparative Example 12.5 Not Added----Comparative Example 20.8 Not Added----Comparative Example 30.4 Not Added----Comparative Example 40.8 Not Added--7 (First Dispersant HLB Value) Comparative Example 50.8 Sodium Polyacrylate 0.28 Comparative Example 60.8 Sodium Polyacrylate 0.18 Comparative Example 70.8 Sodium Polyacrylate 0.038 Comparative Example 80.8 Polyvinyl Alcohol 0.25 Comparative Example 90.8 Na3PO 40.0313 Comparative Example 100.8 Na3PO 40.113

[0096]

[0097] Reference Example: Natural magnesium hydroxide slurry

[0098] In order to verify whether the present invention can replace natural magnesium hydroxide slurry by solving the problems of existing synthetic magnesium hydroxide slurries, a natural magnesium hydroxide slurry was prepared as a reference example by adding 2.5 wt% of polyacrylic acid to 100 wt% of the total Mg(OH)2.

[0099]

[0100] Experimental Example

[0101] Flowability and storage stability were evaluated for the examples, comparative examples, and reference examples. To this end, the solid content and viscosity (P1 to P4) at the time of storage day n were measured for 100 wt% of the total slurry and are shown in Table 2 below. In addition, examples, reference examples, and some comparative examples for which the above Equations 1 to 3 can be calculated are shown in Table 3.

[0102] Looking at Table 2 below, except for Comparative Example 3, the viscosity at the first day of storage was less than 200 cp. However, in the case of the Comparative Examples, it can be seen that storage stability significantly decreased as the viscosity increased rapidly or precipitate hardening occurred from the second day onwards. This is because, as previously mentioned, due to the influence of the coagulant, the atmosphere within the slurry reversed from an anionic tendency to a cationic tendency, causing re-aggregation. In particular, in the case of Comparative Example 1, which had only the same amount of polyacrylic acid as the Reference Example added, the precipitate hardened on the second day of storage, and in Comparative Example 2, which had only the same amount of polyacrylic acid as the Example added, it can be seen that the viscosity reached 4,800 cp on the fourth day.

[0103] In Comparative Examples 5 to 8, in which the second dispersant was replaced with a substance other than a phosphate-based one, the type and content were varied, but it can be seen that the effect did not reach that of the Examples and Reference Examples. Furthermore, in Comparative Examples 9 and 10, in which the same second dispersant as in the Examples was added in small and excessive amounts, it can be confirmed that the effect was reduced.

[0104] On the other hand, it can be seen that the embodiments of the present invention exhibit excellent fluidity and storage stability, with a viscosity of 1000 cp or less on the fourth day of storage, even with only about four times less dispersant than conventional natural magnesium hydroxide. In addition, no hardening of precipitates occurred. That is, it is believed that a high-concentration synthetic magnesium hydroxide slurry product containing 50 wt% or more of Mg(OH)2 can be commercialized through the present invention.

[0105] Item Solids (wt%) P1(cp) P2(cp) P3(cp) P4(cp) Example 5 6.185 195 210 730 Comparative Example 1 56.390 Cured---- Comparative Example 2 55.8120 280 765 4,800 Comparative Example 3 55.74,650 Cured---- Comparative Example 4 55.815 5280 Cured-- Comparative Example 5 56.295 240 590 4,600 Comparative Example 6 56.3120 420 785 8,100 Comparative Example 7 56.4115 350 760 5,200 Comparative Example 8 55.9180 440 1,760 Cured Comparative Example 9 57.1130 315 1,390 Cured Comparative Example 1056.180 Cured--Reference Example 56.7135240265350

[0106] Item P3 / P1 [Equation 1] P4 / P1 [Equation 2] P3 / P2 [Equation 3] Example 2.47 8.58 1.08 Comparative Example 26.38 40 2.73 Comparative Example 56.21 48.42 2.46 Comparative Example 66.54 67.5 1.87 Comparative Example 76.61 45.22 2.17 Comparative Example 89.78 --4 Comparative Example 910.79 --4.41 Reference Example 1.96 2.59 1.10

[0107]

[0108] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

1. Comprising a first dispersant, a second dispersant, Mg(OH)2 and the remainder being water, The content of the above Mg(OH)2 is 50 wt% or more with respect to 100 wt% of the total slurry, and The content of the first dispersant is in the range of 0.5 to 2 wt% with respect to the total 100 wt% of Mg(OH)2, and The content of the second dispersant is in the range of 0.03 to 0.1 wt% with respect to the total 100 wt% of Mg(OH)2, and The HLB (Hydrophilic lipophilic balance) values ​​of the first dispersant and the second dispersant are independently in the range of 8 to 20, Magnesium hydroxide slurry.

2. In Paragraph 1, The HLB value of the first dispersant is in the range of 8 to 15, Magnesium hydroxide slurry.

3. In Paragraph 1, The HLB value of the second dispersant is in the range of 12 to 18, Magnesium hydroxide slurry.

4. In Paragraph 1, The above slurry further includes a coagulant, and The content of the above coagulant is greater than 0 and less than or equal to 800 ppm with respect to the above slurry, Magnesium hydroxide slurry.

5. In Paragraph 1, Satisfying Equation 1 below, Magnesium hydroxide slurry. [Equation 1] 1 ≤ P3 / P1 ≤ 6 (In the above Equation 1, the above P n ... refers to the viscosity of the magnesium hydroxide slurry at the time point n of storage.) 6. In Paragraph 1, Satisfying Equation 2 below, Magnesium hydroxide slurry. [Equation 2] 2 ≤ P4 / P1 < 40 (In the above Equation 2, the above P n ... refers to the viscosity of the magnesium hydroxide slurry at the time point n of storage.) 7. In Paragraph 6, The above P4 is in the range of 200 to 1000 cp, Magnesium hydroxide slurry.

8. In Paragraph 1, Satisfying Equation 3 below, Magnesium hydroxide slurry. [Equation 3] 1 ≤ P3 / P2 ≤ 1.8 (In the above Equation 3, the above P n ... refers to the viscosity of the magnesium hydroxide slurry at the time point n of storage.) 9. In Paragraph 1, The first dispersant comprises at least one of organic acids, polycarboxylates, polyacrylates, polyacrylate copolymers, acrylics, salts thereof, lignosulfonates, polyethylene glycol, polyacrylamide, pyrobosate, sodium citrate, and ammonium citrate. Magnesium hydroxide slurry.

10. In Paragraph 1, The second dispersant is a phosphate-based material comprising at least one of sodium monophosphate, sodium diphosphate, sodium triphosphate, potassium monophosphate, potassium diphosphate, potassium triphosphate, sodium pyrophosphate, potassium pyrophosphate, sodium tripolyphosphate, sodium acid pyrophosphate, sodium hexametaphosphate, and sodium metaphosphate. Magnesium hydroxide slurry.

11. (S1) A step of forming a low-concentration slurry by adding a coagulant to seawater; (S2) A step of preparing a high-concentration slurry containing 50 wt% or more of Mg(OH)2 with respect to 100 wt% of the total by filtering the low-concentration slurry using a centrifugal dehydrator; and (S3) A step of adjusting the concentration by simultaneously introducing the above high-concentration slurry, the first dispersant, the second dispersant, and water into a stirrer; comprising, The above steps (S2) and (S3) proceed continuously. Method for preparing magnesium hydroxide slurry.

12. In Paragraph 11, In the above step (S1), the coagulant is added to the high-concentration slurry such that the concentration is 800 ppm or less. Method for preparing magnesium hydroxide slurry.

13. In Paragraph 11, In the above step (S1), the coagulant comprises a cationic polymer compound, Method for preparing magnesium hydroxide slurry.

14. In Paragraph 13, The above cationic polymer compound comprises at least one of polyacrylamide, polyethyleneamine, polydiallyldimethylammonium chloride, polyamine, epichlorohydrin, and diethylenetriamine, Method for preparing magnesium hydroxide slurry.

15. In Paragraph 11, In step (S3) above, the HLB (Hydrophilic lipophilic balance) values ​​of the first dispersant and the second dispersant are independently in the range of 8 to 20, Method for preparing magnesium hydroxide slurry.

16. In Paragraph 15, The HLB value of the first dispersant is in the range of 8 to 15, Method for preparing magnesium hydroxide slurry.

17. In Paragraph 15, The HLB value of the second dispersant is in the range of 12 to 18, Method for preparing magnesium hydroxide slurry.