KR20060117630A - A concentrate method of minerals from sea water, the mineral concentrate and its use - Google Patents

Abstract

A method for preparing a mineral concentrate by separating and concentrating natural minerals contained in seawater, a mineral concentrate that is prepared by the method and can be properly added to desalinated seawater to replenish minerals to the desalinated seawater, and uses of the mineral concentrate including foods, especially isotonic drinks or nutritious drinks are provided. A method for concentrating minerals contained in seawater comprises the steps of: passing pretreated seawater through a nanofiltration system comprising at least one nanofiltration membrane one or more times to separate and store concentrated water that does not permeate the nanofiltration membrane; concentrating the stored concentrated water by evaporating 90% or more of water from the stored concentrated water; and centrifugally separating the evaporated and concentrated water to obtain a supernatant liquid having a hardness/TDS ratio of 0.5 to 1 and containing a hardness constituent of 200,000 to 400,000 mg/L.

Description

Method of Concentrating Minerals in Seawater and Mineral Concentrates Prepared Using the Same and Their Uses {A Concentrate Method of Minerals from Sea Water, the Mineral Concentrate and its Use}

1 is a block diagram illustrating a mineral concentration process according to a preferred embodiment of the present invention.

Figure 2 is a schematic diagram showing the separation, concentration process of mineral components by the nanofiltration system.

Figure 3 shows a block diagram of the evaporation concentration process according to a preferred embodiment of the present invention.

Figure 4 shows the change in hardness and TDS concentration according to the water evaporation rate in the evaporation concentration process.

Figure 5 shows the change in solubility of calcium chloride, calcium carbonate, sodium chloride with temperature.

6 shows a process and apparatus for concentrating mineral components in seawater according to a preferred embodiment of the present invention.

Figure 7 shows the TDS and hardness of the production water and the concentrated water in each unit process according to a specific embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1: Raw water tank 4,5: Pretreatment filter

6: high pressure pump 9,10,11: nano filtration membrane module

17: nano filtration concentrate tank 21: nano filtration production tank

23: evaporator 24: centrifuge

The present invention relates to a method for concentrating mineral components in seawater, and to mineral concentrates prepared using the same, and the use thereof, in particular, by separating and concentrating the mineral components in seawater separately, adding seawater to desalted water or supplying natural minerals. The present invention relates to mineral concentrates in seawater which can be used in various fields.

The tap water currently in use is purified polluted rivers or lake water by various means. However, it takes a lot of energy and time to restore the polluted water to its original state. However, current limited water resources may cause serious water shortages worldwide. In recent years, interest in the ocean, which occupies about 71% of the earth's area, has been increasing. In fact, Korea has three sides facing the sea, and its active use is being considered as a way to solve the water shortage problem in the future. In particular, deep sea water has recently been recognized as a sustainable alternative to natural circulation, and its application is being studied and reviewed in various industries.

In general, the reverse osmosis method, the evaporation method and the like have been widely used in the desalination process for use as water for drinking seawater. In particular, the reverse osmosis method is widely used as a seawater desalination technology, there is a problem that the water produced by the reverse osmosis method is mostly removed to the mineral components required by the human body.

On the other hand, deep sea water and sea water contain various kinds of minerals, especially hardness components such as calcium and magnesium are contained in large amounts compared to surface water. However, in the case of seawater and deep sea water, salt is a significant part, and if the separation of salts is required, a technology capable of separating only salts and taking useful hardness and mineral components can be developed. As an excellent water resource to supply minerals, seawater is expected to have tremendous development effects.

Korean Unexamined Patent Publication No. 1995-0029195 and Utility Model Registration No. 0309654 describe the desalination apparatus of seawater using electrolysis, and Japanese Unexamined Patent Publication No. 2001-0106805 and Japanese Patent Publication No. 2003-0021027 disclose seawater using an evaporation method. The desalination apparatus of the present invention is described, and Utility Model Registration No. 0373511 et al describes the desalination apparatus of seawater using reverse osmosis. Korean Patent Laid-Open No. 2001-0106805 proposes a method of preparing salt using a high concentration of brine obtained during desalination. However, sufficient research has not yet been conducted on techniques for effectively separating and concentrating natural minerals contained in seawater such as calcium and magnesium.

The present invention focuses on the problem of eliminating salts as well as mineral components in seawater by current seawater desalination technology (especially reverse osmosis) and the fact that natural mineral components contained in seawater are not properly utilized. The primary object of the present invention is to provide a mineral concentrate by separating and concentrating natural minerals contained in seawater. The mineral concentrate to be provided in the present invention has a primary use of replenishing minerals by appropriate addition to desalted seawater. However, the use of the mineral concentrate of the present invention is not limited thereto, and may be used in various fields in which minerals are used for the purpose of dissemination to a living body, for example, foods, particularly ion electrolyte drinks or nutrients.

Another object of the present invention is to separate and concentrate the mineral components in the seawater necessary for the human body and add the seawater to the desalted water to solve the problem of mineral removal, which was a problem of the existing desalination method, and furthermore, as the excellent water resource for seawater. It is an object of the present invention to be actively utilized.

Other objects and advantages of the invention will be described below, and will be better understood by practice of the invention.

In order to achieve the above object, the present invention comprises the steps of passing through the pre-treated seawater at least one nanofiltration system consisting of one or more nanofiltration membrane to separate and store the concentrated water that does not penetrate the nanofiltration membrane; Evaporating and concentrating at least 90% moisture in the stored concentrated water; Centrifuging the evaporated concentrated in the above step is provided a mineral concentration method in seawater comprising the step of obtaining a supernatant having a hardness / TDS ratio of 0.5 to 1 and a hardness component of 200,000 to 400,000 mg / L.

In the present invention, "sea water" refers to all kinds of seawater regardless of the place or method of harvesting such as general seawater, deep seawater, underground rock and seawater. In general, deep sea water is defined as clean seawater that exists in deep seas with a depth of 200m or more that sunlight does not reach and the water temperature is stable below 2 ℃ throughout the year. In general, the underground rocky seawater penetrates hundreds of meters deep in the coastal region and is discharged through the ground at the time of pumping. Therefore, it can be defined as seawater having water quality characteristics that are comparable with deep seawater and surface water.

In general, the membrane method is divided into microfiltration, ultrafiltration, nanofiltration, reverse osmosis according to the pore size of the membrane. Nanofiltration membrane can be seen as a kind of reverse osmosis membrane in a broad sense, but it can produce a large amount of water while operating at low pressure than reverse osmosis membrane. In particular, the reverse osmosis membrane has a rejection rate of 90% or more for all ions in water, whereas a nanofiltration system using a nanofiltration membrane has a rejection rate of about 50 to 80% or more for divalent ions and 20 to 1 ion for ions. It has a characteristic of having a relatively low rejection rate of about 50%. Therefore, the pore size of the nanofiltration membrane constituting the nanofiltration system is smaller than the ultrafiltration membrane and larger than the reverse osmosis filtration, and the surface of the membrane has a charged characteristic. The nanofiltration system of the present invention is composed of one or more nanofiltration membranes and has a relatively low exclusion rate of about 50 to 80% for divalent ions and about 20 to 50% for monovalent ions. If it has a can be used for the purpose of the present invention. In a preferred embodiment of the present invention, the nanofiltration system is composed of three nanofiltration membrane modules, and pressurized seawater using a high pressure pump to flow into the nanofiltration membrane module and permeated water that passes through the nanofiltration membrane and concentrated water that is not permeable. To be separated.

Hereinafter, in the present invention, "concentrated water" refers to a portion of the influent that is not permeable to the nanofiltration membrane and is excluded, and "permeate" refers to a portion of the influent that permeates the nanofiltration membrane. In addition, the portion of the influent passing through the nanofiltration membrane is also referred to as "production water".

The concentrated water separated and stored without permeation of the nanofiltration membrane may have a total hardness of 25,000 to 35,000 mg CaCO3 / L, TDS (Total Dissolved Solid) of 30,000 to 40,000 mg / L, and a ratio of total hardness / TDS of 0.6 to 1.0. It will have a range of.

Pretreatment of seawater in this invention means the process of removing the foreign material in seawater. In a preferred embodiment of the present invention, seawater is pretreated using a filtration membrane having pores of the appropriate size.

In the present invention, by concentrating the divalent mineral component in the seawater by nanofiltration, it is possible to prepare a concentrate containing a large amount of bivalent hardness components compared to the concentrate made by simple evaporation.

In the present invention, the concentrated water passed through the nanofiltration system is preferably evaporated to 95% of water and then centrifuged to take a supernatant, which is the final mineral concentrate.

The mineral concentrate of the present invention is obtained in the form of a mixture of liquids. However, the mineral concentrate of the present invention is not limited to this form, and it is also possible to add a known process to make the liquid mixture into another form (for example, powder, granule, soft capsule, etc.).

In addition, in the present invention, the pretreated seawater is passed through a nanofiltration system composed of one or more nanofiltration membranes at least once to obtain concentrated water that does not penetrate the nanofiltration membrane. A mineral concentrate in seawater having a hardness / TDS ratio of 0.5 to 1 and a hardness component of 200,000 to 400,000 mg / L obtained as a supernatant is provided.

In particular, the mineral concentrate of the present invention may be used for supplementing insufficient mineral components by adding to desalted water. The use of these mineral concentrates is to solve the problem of mineral removal, which was a problem of the existing desalination method, to provide a way that seawater can be used as an excellent water resource.

In addition, the mineral concentrate of the present invention can be used as a source of natural mineral components, such as various foods such as ionic electrolyte beverages and nutritional supplements for mineral supplementation.

Hereinafter, the method for concentrating minerals in seawater according to the present invention will be described in detail step by step.

1 is a block diagram showing a mineral concentration process according to an embodiment of the present invention. The process is divided into nanofiltration process, evaporation concentration process and centrifugation process.

1. Nanofiltration Process

The pretreated seawater is passed through a nanofiltration system consisting of one or more nanofiltration membranes one or more times to separate and store concentrated water that has not passed through the nanofiltration membrane.

First, seawater is subjected to a pretreatment step of removing foreign matter by passing through a filtration membrane having a pore of a suitable size. In a preferred embodiment of the present invention, a filtration membrane of 3 to 5 μm is passed, and larger or smaller pores are also possible. In addition, other known methods may be used in addition to the membrane separation method to remove foreign substances in seawater, and depending on the characteristics of the seawater, it is possible to add another foreign matter removal step to the membrane separation method or to omit the pretreatment process itself.

The pretreated seawater is separated into permeate that enters the nanofiltration system using a high pressure pump and permeates that pass through the nanofiltration membrane and concentrates that do not permeate. The principle of mineral concentration by nanofiltration system is as follows.

Since nanofiltration membranes are charged in water, they are closely related to the chargeability of particles and exhibit characteristic removal characteristics for ionic components. As a result, there is a significant difference in the removal rate of monovalent and divalent ions. Specifically, monovalent ions such as Na ⁺ , K ⁺ , and Cl ^- penetrate the membrane well, but divalent ions such as Ca ²⁺ and Mg ²⁺ The component concentrates without permeating the membrane well. Figure 2 conceptually shows that the ratio of ionic components in seawater changes in concentrated and produced water as they pass through the nanofiltration system. Divalent cation components, such as calcium and magnesium, are present in the production water and abundant in the concentrated water. On the other hand, monovalent cation components such as sodium and potassium are present in the production water and less in the concentrated water.

The concentrated water produced by nanofiltration has a total hardness of about 25,000 to 35,000 mg CaCO3 / L, a total dissolved solid (TDS) of 30,000 to 40,000 mg / L, and a total hardness of TDS. The ratio is 0.6 or more and 1.0 or less.

2. Evaporative Concentration Process

The water of the concentrated water stored in the process is evaporated and concentrated at least 90%. In the present invention, the evaporation method is introduced to concentrate the hardness concentration of the concentrated water obtained by the nanofiltration system to a higher concentration. As described above, the present invention can be obtained by applying the nanofiltration and the evaporation concentration method together, thereby obtaining a concentrate containing much more bivalent hardness components than the case of simply using the evaporation method. Preferably, the water of the concentrated water which has passed through the nanofiltration system is evaporated to 95%. Since the rate of concentration of TDS and hardness increases rapidly after evaporating the water of the concentrated water by 70%, more preferably, the evaporation process is more efficient by evaporating the water about 70% and collecting the supernatant water and evaporating again to 95% of the water. Can operate. Figure 3 shows a block diagram of the evaporation concentration process according to a preferred embodiment of the present invention.

3. Centrifugation process

Centrifuging the evaporated and concentrated in the above process to obtain a supernatant having a hardness / TDS ratio of 0.5 to 1 and a hardness component of 200,000 to 400,000 mg / L.

Most of the components present in the liquid concentrate after evaporative concentration of the process are calcium chloride or magnesium chloride. In particular, the behavior of calcium chloride can be explained by the effect of solubility with temperature changes. Figure 5 shows the change in solubility of calcium chloride, calcium carbonate, sodium chloride with temperature. In the case of calcium chloride, the solubility is dissolved in 100 mL or more at a temperature of around 100 ° C. or more, so that the precipitated material is mostly sodium chloride and the remaining material in the supernatant is mostly calcium chloride. On the other hand, since the carbonate component is almost released into the atmosphere at 100 ° C, the amount of precipitation of the component of the calcium carbonate becomes extremely small.

Therefore, the supernatant is finally evaporated and concentrated in the above process for 20 to 2 hours at 1000 to 5,000 rpm in a centrifuge, and the hardness / TDS ratio is in the range of 0.5 to 1 and the hardness component is 200,000 to 40. The mineral concentrate of the present invention can be obtained in the form of a liquid mixture of 10,000 mg / L.

6 shows a process and apparatus for concentrating mineral components in seawater according to a preferred embodiment of the present invention. However, the present invention is not limited to the apparatus shown.

First, seawater (underground brine) is collected in the raw water tank 1 and supplied to the pretreatment filter 5 탆 (4) and the pretreatment filter 3 탆 (5) by the feed pump (3). The pretreated feed water is supplied to the nanofiltration membrane module 9 through the nanofiltration feed water line 14 by the nanofiltration high pressure pump 6. The flow rate of the feed water and the TDS are measured by the flow meter 8 and the TDS meter 7 of the feed water of the feed water pipe 14. Nanofiltration system is composed of a total of three nanofiltration membrane modules (9, 10, 11), preferably can be operated under the conditions of 10 ~ 15kgf / cm ² . The concentrated water of the nanofiltration membrane module 1 (9) is supplied to the nanofiltration membrane module 2 (10) through the concentrated water pipe 12, and the concentrated water of the nanofiltration membrane module 2 (10) again through the concentrated water pipe (13). 3 (11). The nanofiltration production water passing through the nanofiltration membrane modules 9, 10 and 11 is moved to and stored in the nanofiltration production water tank 21 through the final production pipe 20 connected to the nanofiltration membrane modules 9, 10 and 11. do. The production flow rate and TDS of the nanofiltration production water are measured by the flow meter 19 and the TDS meter 18. On the other hand, since there is a possibility that coexistent metal substances in raw water or the like may be concentrated in the primary concentrated water that does not penetrate the nanofiltration membrane module, the storage valve 16 of the final concentrated water pipe 15 is preferably passed through ( by-pass).

After the nanofiltration production tank 21 is filled with the nanofiltration production water (primary), the raw water supply control valve (2) is closed, and the nanofiltration production water (primary) obtained in the above process is filled with the nanofiltration supply pipe (25). Supply through). The supplied nanofiltration water (primary) is supplied to the pretreatment filters 4 and 5 by the supply pump 3 and pretreated, and then the nanofiltration membrane module through the supply water pipe 14 by the high pressure pump 6 ( 9) is supplied. The supply flow rate and the TDS of the nanofiltration production water (primary) are measured by the flow meter 8 and the TDS meter 7 of the supply water pipe 14. The rest proceeds in the same manner as the above process, and the nanofiltration production water (secondary) passing through the nanofiltration membrane modules 9, 10, and 11 is moved to and stored in the nanofiltration production water tank 21. The production flow rate and TDS of the nanofiltration production water (secondary) are measured by the flowmeter 19 and the TDS meter 18. Here, the nanofiltration concentrate water (secondary) is stored in the nanofiltration concentrate tank 17 by opening the storage valve 16 of the nanofiltration concentrate pipe (15).

The raw water supply control valve 2 is closed and the nanofiltration concentrate water (secondary) obtained in the above process is supplied through the nanofiltration supply pipe 26. The nanofiltration concentrated water (secondary) is supplied to the pretreatment filters (4, 5) by the supply pump (3) and pretreated, and then supplied to the nanofiltration membrane module (9) through the supply water pipe (14) by the high pressure pump (6). Supplied. The supply flow rate and the TDS of the nanofiltration concentrated water (secondary) are measured by the flow meter 8 and the TDS meter 7 of the supply water pipe 14. The rest proceeds in the same manner as the above process. The nanofiltration production water that has passed through the nanofiltration membrane module is transferred to and stored in the nanofiltration production tank 21 through the nanofiltration production pipe 20, where the production flow rate and TDS of the nanofiltration final production water is measured by a flow meter (19). And by TDS system 18. The nanofiltration concentrate (third) is stored in the nanofiltration concentrate tank 17 by opening the storage valve 16 of the nanofiltration final concentration pipe 15.

The nanofiltration concentrated water (tertiary) obtained in the above process is sent to the evaporator 23 to evaporate and concentrate 95% of the total water, and then centrifuged at 3,000 rpm for about 1 hour using a centrifuge 24 to obtain supernatant. This supernatant is the desired final mineral concentrate. The mineral concentrate of the seawater thus obtained has a hardness / TDS ratio in the range of 0.5 to 1, and forms a liquid mixture having a hardness component of 200,000 to 400,000 mg / L.

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the scope of the present invention is not limited by the following examples.

Example 1

Preparation of Mineral Concentrate Using Underground Seawater

The operating conditions and recovery rates for each unit process are shown in Table 1 below. Underground seawater was used as raw water, and the mineral concentrate was prepared according to the method of the preferred embodiment shown in FIG. As a nano filtration membrane constituting the nano-system was used SU-610 of TORAY, Japan. The change in hardness and TDS concentration according to the water evaporation rate in the evaporation concentration process is shown in FIG. 4, and the TDS and hardness of the produced water and the concentrated water in each unit process are shown in FIG. 7.

Table 2 shows the results of analyzing the prepared final mineral concentrate and underground seawater as raw water. As can be seen from Table 2, the underground seawater is an underground seawater existing in the rock layer 800m and contains 3.5 times the calcium content and 1.3 times the hardness of the seawater components. Therefore, underground seawater is particularly suitable as raw water of mineral concentrates containing calcium and magnesium as main components.

Mineral concentrate according to the present invention can be used as a source of natural minerals in various fields for the purpose of mineral replenishment to the living body, for example, food, in particular ion electrolyte drink or nutrient, etc., in particular the present invention By separating and condensing the mineral components in the water to be added to the desalted seawater can be used as a way to solve the problem of conventional seawater desalination, and further active use of seawater.

Claims (11)

Passing the pretreated seawater through a nanofiltration system consisting of one or more nanofiltration membranes one or more times to separate and store concentrated water that does not penetrate the nanofiltration membrane; Evaporating and concentrating at least 90% moisture in the stored concentrated water; Centrifuging the evaporated concentrated in the step to obtain a supernatant having a hardness / TDS ratio of 0.5 to 1 and a hardness component of 200,000 to 400,000 mg / L. The method of claim 1, wherein the separated and stored concentrated water has a total hardness of 25,000 to 35,000 mg CaCO3 / L, a TDS of 30,000 to 40,000 mg / L, and a total hardness / TDS ratio of 0.6 to 1.0. The method of claim 1, wherein the evaporating and concentrating step comprises evaporating and condensing the supernatant water after evaporating more than 70% of the water in the concentrated water and concentrating the evaporation. The method of claim 3, wherein the supernatant is separated and concentrated by evaporation of at least 95%. The method of any one of claims 1 to 4, wherein the separating and storing of the concentrated water passes the pretreated seawater through the nanofiltration system to discard the primary concentrated water that has not permeated the nanofiltration membrane and permeates the nanofiltration membrane. One primary production water is passed through a nanofiltration system to separate and store concentrated water (secondary). The method according to claim 5, wherein the concentrated water (secondary) is passed through a nanofiltration system to separate and store the concentrated water (third). Pass the pretreated seawater one or more times through a nanofiltration system consisting of one or more nanofiltration membranes to obtain concentrated water that does not penetrate the nanofiltration membrane. Mineral concentrate in seawater with a TDS ratio in the range of 0.5 to 1 and a hardness component of 200,000 to 400,000 mg / L. A method for producing drinking water, comprising adding mineral concentrate of claim 7 to desalted water. Drinking water obtained by the method of claim 8. An ion electrolyte drink comprising the mineral concentrate of claim 7. A nutritional supplement for mineral supplementation comprising the mineral concentrate of claim 7 as an active ingredient.

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