KR100977527B1 - Method for purifying heavy metal contaminated soil slurry using magnetic field - Google Patents

Abstract

PURPOSE: A heavy metal contamination fine soil slurry purifying method is provided to reduce the volume of the waste which is generated when soil is purified and improve removing efficiency of contaminants. CONSTITUTION: A heavy metal contamination fine soil slurry purifying method comprises following steps. A soil particle is dispersed by injecting inorganic dispersing agent and surfactant. The soil particle is magnetized by injecting magnetization agent within the fine soil slurry. A mineral particle containing heavy metal is divided from the dispersed and magnetized fine soil slurry by using a magnetic separating device(S140). The mineral particle containing heavy metal, which is separated from the fine soil slurry, is collected.

Description

Method for purifying heavy metal contaminated soil slurry using magnetic field}

The present invention relates to a method for purifying heavy metal contaminated micro soil slurry using a magnetic field, and more particularly, to a method for purifying heavy metal contaminated micro soil slurry using a magnetic field capable of removing heavy metal materials from a micro soil slurry using magnetic separation. .

Soil pollution occurs through various routes such as waste dumping, sludge after wastewater treatment, leakage of harmful substances, use of pesticides and fertilizers, incineration, and sediments (rivers, oceans, lake bottoms). Soil pollution not only causes direct problems in many forms such as soil, rivers, marine ecosystem disruption, crop pollution, and human absorption of pollutants, but also acts as a source of pollution causing surface water, groundwater, fisheries, and air pollution. In particular, heavy metals are known to cause Minamata, Itai-tai, cancer, etc., much effort is required to reduce the damage caused by heavy metals through pollution prevention and purification of contaminated soil.

Recently, the heavy metal contaminated soil has been actively purged, and the main cleaning methods are soil washing, electrokinetic extraction, and stabilization methods. These methods have many limitations in achieving the restoration goals specified in the Soil Ring Warning Act.

By the type of initial pollutants present in the contaminated soil, water soluble, replaceable, carbonate, Fe-oxide, Mn-oxide, organic ) And the residual form. The content ratio of heavy metals from soil to soil type is used as main data for selection, application and monitoring of purification methods depending on the behavior and toxicity of heavy metals. Heavy metal contaminated soil purification methods are classified into elution and stabilization methods to reduce the toxicity and mobility of heavy metals in soil, soil washing, and electrokinetic extraction.

However, in the case of soil washing and purifying heavy metal contaminated soils using electrokinetic extraction, iron and manganese oxides in the form of minerals and heavy metals in the form of residuals are often difficult to achieve. In addition, when restoring the soil by applying the stabilization method has a focus on stabilizing heavy metals of water-soluble and replaceable form, there is a disadvantage that it is difficult to secure the durability of the recovery efficiency. In other words, when the soil washing and stabilization method is applied to soils with a high content of iron or manganese oxide having a heavy metal content and a residual form, the purifying target cannot be achieved due to limited extraction or stabilization efficiency. Difficult cases are occurring.

Moreover, the removal of heavy iron in the form of amorphous iron or manganese oxide and residual forms from the soil can only be achieved by using a high extractable solution using conventional soil washing methods. The use of high extractable solutions has the disadvantages of corrosion of washing equipment and costly wastewater treatment.

The present invention, by using the magnetic field of the heavy metal-containing mineral particles and the magnetic field of the high gradient magnetic separator to intensively extract and remove the heavy metal-containing mineral particles from the fine soil slurry using a magnetic field, It is an object of the present invention to provide a method for purifying heavy metal contaminated fine soil slurry.

The present invention comprises the steps of dispersing the soil particles in a fine soil slurry by dispersing, and heavy metal-containing mineral particles from the dispersed fine soil slurry using a high gradient magnetic separation (HGMC) using a magnetic field It provides a heavy metal contamination fine soil slurry purification method using a magnetic field comprising the step of magnetic separation to remove.

In the above, before the step of dispersing the soil particles, it may further comprise the step of removing the foreign matter in the fine soil slurry, and removing the odor and organic matter from the fine soil slurry from which the foreign matter is removed.

In addition, after the magnetic separation step, by recovering the heavy metal-containing mineral particles attached to the high gradient magnetic separator by the magnetic separation separated from the fine soil slurry, the remaining slurry from which the heavy metal-containing mineral particles are removed Separating into soil slurries of less than A ㎛ diameter and less, performing the magnetic separation for the soil slurries of less than A ㎛ using the high gradient magnetic separator, and the secondary magnetic separation through the The method may further include separating and removing the heavy metal eluted by adding a chemical treatment agent to the soil slurry of less than A μm.

And, the purification method, the step of dewatering the soil slurry of the A ㎛ or more separated from the residual slurry to use as purified soil, and the step of dewatering the soil slurry from which the heavy metal is removed to use as purified soil It may include.

And, the step of dispersing the soil particles, it can be dispersed using an inorganic series dispersant and a surfactant in the concentration range of 1 ~ 10000ppm. In addition, the magnetic separation step, may be performed in a magnetic field of 1 ~ 5T range.

And, before the magnetic separation step, to increase the efficiency of the magnetic separation, it may further comprise the step of magnetizing the soil particles by putting a magnetizing agent in the fine soil slurry. Here, the step of magnetizing the soil particles, the magnetite using Fe ₃ O ₄ as the magnetizing agent in the fine soil slurry to the magnetite to act as a bridge between the soil particles to make the magnetic, The iron component dissolved in the magnetite is dissolved to act as a bridge between the soil particles to make the magnetism, or the fertilizer salt is dissolved as the magnetizing agent, adjusted to an alkaline state, and then air is introduced and the temperature is increased. The soil particles may be magnetized by introducing into the soil slurry.

In addition, the present invention, the step of removing the foreign matter in the fine soil slurry, dispersing or magnetizing the soil particles by the dispersant or magnetizing agent in the fine soil slurry, high conductivity using a magnet selected from a superconducting magnet, electromagnet, permanent magnet Setting a gradient magnetic separation (HGMC) to a magnetic field strength in the range of 1 to 5T to magnetically separate and remove heavy metal-containing mineral particles from the dispersed or magnetized fine soil slurry, and by the magnetic separation Provided is a heavy metal contamination fine soil slurry purification method using a magnetic field attached to the high gradient magnetic separator to recover the heavy metal-containing mineral particles separated from the fine soil slurry.

According to the method for purifying heavy metal-contaminated fine soil slurry using the magnetic field according to the present invention, by intensively extracting and removing heavy metal-containing mineral particles from the fine soil slurry using the magnetic properties of the heavy metal-containing mineral particles and the magnetic field of the high gradient magnetic separator. There is an advantage to increase the removal efficiency of contaminants. Reduce the volume of waste from soil cleanup.

1 is a flowchart of a method for purifying heavy metal contaminated micro soil slurry using a magnetic field according to an exemplary embodiment of the present invention. 2 is an exemplary configuration diagram for the purification method of FIG. 1.

Here, in the present invention, the heavy metal-contaminated fine soil slurry, which is the subject of purification, is a fine soil slurry contaminated with heavy metals of less than 1 mm in diameter such as lakes, land, rivers, marine sediments, sewage sludge, dredged soil, wastewater sludge, and purified sludge. It is self-explanatory to include. Hereinafter, a method for purifying the heavy metal-contaminated fine soil slurry will be described in more detail with reference to FIGS. 1 and 2.

First, remove foreign substances in the fine soil slurry of less than 1mm (S110). This step S110 is removed by using a vibrating dewatering screen (110) to separate the foreign matter, contaminants other than soil in the fine soil slurry, particle size screening and washing.

Next, the odor and organics are removed from the fine soil slurry from which the foreign matter is removed (S120). This step S120 is performed by adding a odor remover, an organic remover in the odor and organic matter removing tank 120. Specific configuration of the odor and organic matter removal process can be selectively applied from a variety of known methods, a more detailed description thereof will be omitted.

The odor removal removes odors such as H ₂ S, metcaptan, and ammonia from odorous substances generated from deposits, organic sludge, and manure. The mechanism of odor removal is as follows.

Thereafter, the dispersant is added to the fine soil slurry from which the foreign substances and odors are removed to disperse the soil particles in the dispersion tank 130 (S130). This process and subsequent processes are applicable even if a small amount of clay is included in the contaminated microsoil slurry.

In the case of dispersing the soil particles in the form of granules in advance by using the dispersant, there is an advantage that can enhance the effect and performance of the magnetic separation of the heavy metal-containing mineral particles carried out in the subsequent magnetic separation step (S140). This is because the magnetic separation step (S140) is advantageous the smaller the size of the soil particles.

In other words, the dispersing step (S130) is a preliminary step of the heavy metal contamination fine soil slurry purification method using the magnetic field, and acts as a flocculant at the soil inlet, or the heavy metal-containing mineral precipitated on the coarse surface in water It is to disperse completely to enlarge the contact surface and to exist as individual particles.

As the dispersant, an inorganic dispersant (eg, sodium dispersant) and a surfactant in a concentration range of 1 to 10000 ppm are used. When the dispersant is used at a concentration of 1 ppm or less, the dispersion efficiency is lowered, and when used at a concentration of 10000 ppm or more, the dispersion efficiency is not significantly different from that at a concentration below that, and materials may be wasted.

The basic principle of the dispersion process of the soil particles using the dispersant is as follows. Paramagnetic minerals, iron oxides, manganese oxides, heavy metal hydroxides, heavy meatal oxdies, secondary minerals produced during weathering that contain heavy metals, Heavy metal sulfate and the like have a particle size of clay or fine misato, and tend to aggregate around primary minerals, which are main components of gravel and sand, to form soil aggregates.

In order to separate and extract paramagnetic minerals containing heavy metals from the fine soil slurry, the heavy metal-containing minerals should be dispersed to exist as individual particles. The heavy metal-containing mineral may vary depending on the dispersion conditions of the particles in the aqueous solution state, and acts as a flocculant at the soil inlet or precipitates on the granulated particle surface through the surface charge of the soil particles and the chemical properties of the aqueous solution. Means.

The surface charge of soil particles is divided into permanent charge originating from the mineral crystal structure and variable charge determined by the surrounding physicochemical environment. Disperses soil particles by inducing the generation of variable charges at their cuts (cut surfaces) through 'controlling the charge on the surface of soil particles with permanent negative charge or variable charge' and 'controlling the chemical properties of the aqueous solution' You can.

Specifically, as an example of the charge control of the surface of the soil particles, iron oxide and manganese oxide mineral having a variable charge, as the surface has a positive charge, the clay mineral and organic material having a surface negative charge through the connection of the electrostatic force It acts to aggregate. Further, as an example of the "control and chemical properties of the aqueous solution", to increase the pH of the solution above the isoelectric point of the mineral, or a phosphate on the surface of the mineral (PO ₄ ^{3 -;} phosphate) and a surface attraction force as strong as multi-charge By adsorbing multi-charged anions, the surface charges of the minerals (iron oxide, manganese oxide minerals) are converted to negative charges, and the soil particles are dispersed in a repulsive action.

'Dispersion of soil particles' through 'controlling the chemical properties of aqueous solutions' is possible by controlling the type (concentration) and the charge (size, ratio) of dissolved ions. In particles having a surface charge, ions having opposite charges are adsorbed such that the total charge of the surface becomes zero in the aqueous solution. The structure of the adsorption layer is determined by the charge, size and concentration of the ions. The structure of this adsorption layer is described as a diffuse double layer, and the thickness of the layer becomes thicker as the charge and concentration of ions are lower. For definition of the diffusion double layer, refer to previously known data.

When the thickness of the adsorption layer is thick, the soil particles are easily dispersed in the aqueous solution, but when the thickness of the adsorption layer is thin, they easily aggregate. Ca ^{2 +} and Mg ^{2 +} , which have multi-charged cations, have a smaller thickness of the diffusion double layer than Na ⁺ , and tend to aggregate negatively charged soil particles through bridging. Dispersion and aggregation characteristics of the soil particles are expressed by sodium adsorption ratio (SAR), which is a ratio of monovalent and divalent ions.

SAR = (Na ⁺ ) / [(Ca ^{2 +} + Mg ^{2 +} ) / 2] ^0.5

In this case, when the concentration of dissolved ions is the same, the higher the SAR value, the higher the soil particles exhibit the dispersion characteristics.

In the heavy metal contaminated soil purification method using the magnetic field, the dispersion of the soil particles can maximize the negative charge of the mineral surface having a variable surface charge and the thickness of the diffuse double layer. Derivation of a solution. Therefore, in order to minimize the elution of heavy metals from the soil particles, and to smoothly disperse, in the dispersing step (S130), it is to use the inorganic-based dispersant verified as a dispersion solution in the field of soil mineralogy.

For example, in the case of using a sodium (Na) -based inorganic dispersant, sodium saturates heavy metals and exchangeable cations in the soil, increases the pH of the solvent, adsorbs phosphoric acid (PO ₄ ^{3 −} ), and Negative charge will be applied to the cut surface. Sodium ions are cations with high water affinity, increase the repulsion of the particle surface, prevent aggregation and effectively induce dispersion among soil particles. As described above, the dispersing step (S130) represents a step of cation exchange reaction, isoelectric point control and dispersion of the soil bonded in the form of a particle.

Meanwhile, referring to FIG. 1, in addition to the process of dispersing the soil particles by adding the dispersant, there is a process of magnetizing the soil particles by injecting a magnetizer into the fine soil slurry (S130). This magnetizing agent input process is to increase the magnetic susceptibility of the soil particles in order to increase the efficiency of magnetic separation of the heavy metal-containing mineral particles in the fine soil slurry in the future, the magnetic separation process using a magnetic field (S140) Is performed before. Therefore, the above-described magnetizer addition step (S130) is performed at a point in time between the odor and organic matter removal step (S120) and the magnetic separation step (S140), before or after the dispersant, or a dispersant It can be carried out simultaneously with the input, and the order can be changed.

The magnetization power of the soil particles and the heavy metal content has a high correlation. It means that minerals with high magnetization contain more heavy metals than those with low minerals. In addition, iron oxide, manganese oxide, and residual heavy metals have a relatively high magnetization power compared to silicate minerals (silicates or silicate minerals), so that they can be removed later by using magnetic fields to purify the contaminated soil.

The magnetizing agent, in the subsequent magnetic separation step (S140) to maximize the intensity control of the magnetic field for each magnetization of the mineral and the adhesion of the oxidized mineral and the residual mineral, and to adjust the surface appearance, the retention time and magnetic properties of the magnetic As a non-magnetic mineral in the soil particles, it can be converted into a magnetic mineral, and serves to increase the magnetization power of the weak magnetization power.

As the magnetizing agent, magnetite (Fe ₃ O ₄ ), a ferromagnetic mineral, is used as follows. When the magnetite is introduced into the fine soil slurry, the magnetite acts as a bridge between the soil particles, thereby making the soil particles magnetic. Here, in addition to the magnetite itself acts as a crosslinking role, the iron (Fe) component contained in the magnetite is dissolved to act as a crosslinking between the soil particles it is possible to make the magnetism.

In addition, as the magnetizing agent, a ferric iron salt (FeCl ₂ , FeCl ₃ , FeSO _4, etc.) was used as follows. After dissolving the ferric salt in a solvent to adjust to an alkaline pH state, after adding air and raising the temperature, it is a method of magnetizing the soil particles by adding into the fine soil slurry. Here, the Fe component also acts as a bridge between the soil particles to make the magnetism.

As described above, the role of the magnetizing agent, by increasing or lowering the pH of the solution, by controlling the oxidation action and the relative isoelectric point, to combine the magnetized material with the electrostatic force to the mineral having a weak magnetization force to have a high magnetization power. The concentration of the magnetizing agent to magnetize the soil particles may be used 10-500mg / L, but is not necessarily limited thereto.

After dispersing (or magnetizing agent) into the fine soil slurry and adjusting the pH to disperse or magnetize the soil particles (S130), a high gradient magnetic separator using a magnetic field (HGMC; High gradient magnetic separation) The heavy metal-containing mineral particles are magnetically separated and removed from the dispersed (or magnetized) fine soil slurry by using (S140).

For example, the high gradient magnetic separator 140 using a magnet selected from a superconducting magnet, an electromagnet, and a permanent magnet is set to a magnetic field strength in the range of 1 to 5T (Tesla), and thus, from the dispersed (or magnetized) fine soil slurry. Heavy metal-containing mineral particles are removed by magnetic separation. According to this, the magnetic properties of crystalline iron oxide (Fe-oxides), manganese oxide (Mn-oxides), the residual heavy metal containing minerals occupy more than 50% in the soil, and the strength of the magnetic field of the high gradient magnetic separator 140 Control can be used to extract and remove heavy metal containing minerals from the microsoil slurry.

In summary, according to the high gradient magnetic separator 140, the heavy metal-containing mineral particles in the fine soil slurry are collected using the magnetic field. That is, the heavy metal-containing mineral particles are separated from the fine soil slurry by the magnetic separation and are collected and attached to the high gradient magnetic separator 140. The heavy metal attached to the high gradient magnetic separator 140 is later recovered and disposed of. Therefore, according to this process, the heavy metal-containing mineral particles from the fine soil slurry having a diameter of 1 mm or less, or a mixture such as a river, a marine sediment sludge, or a wastewater sludge or a purified sludge can be effectively used by using a high gradient magnetic separator 140. Can be separated

Hereinafter, the principle of magnetic separation of heavy metal-containing minerals using the high gradient magnetic separator 140 will be described. The high gradient magnetic separator 140 collects and removes heavy metal materials by magnetic force using a magnet and a magnetic field. The magnetic separation is a physical separation process of separating a substance based on the magnetizing power, and because the process is related to the physical composition rather than the chemical composition, there is an advantage that the separation of heavy metals occurs while generating a minimum amount of secondary waste. In the magnetic separation step (S140), it is possible to magnetically separate the heavy metal mineral through the magnetic properties of the mineral containing a large amount of heavy metal, and the intensity of the magnetic field through the high gradient magnetic separator (140).

The spacing between two poles can be up to 4 inches, and the space between them is equipped with a porous ferromagnetic screen net. This magnetic separation method is a method of processing paramagnetic fine particles at high speed by combining a high porosity magnetic filter (porous ferromagnetic screen network) and a magnet capable of generating a high magnetic field. The basic principle of superconducting magnetic separation is to separate the magnetic particles contained in the liquid by a strong magnetic force, and the magnetic particles are removed by being pulled and captured by the magnetic field.

The high gradient magnetic separator 140 requires a magnetic field of 1,000 gauss or more to remove heavy metal-containing mineral particles having very weak magnetic properties. Generally, more than 75KW of power is required, and the coil diameter of the electromagnet should be less than 50 centimeters. The flow rate of the microsoil slurry passing through the magnetic separation should be a flow rate of 4L / min or less, if the speed is faster than that should give the residence time gradient angle.

The principle of the magnetic separation is described again as follows. Paramagnetic particles move in the direction of increasing magnetic gradient when they encounter a non-uniform magnetic field. Semi-magnetic particles are adversely affected. When the magnetic gradient is sufficiently high in intensity, paramagnetic particles are physically captured and separated from the external semimagnetic material. As many soil elements are diamagnetic, it is obvious that magnetic separation of paramagnetic pollutants from soil is easy.

Various magnetic separation methods exist, but the high gradient magnetic separator 140 is suitable for soil purification. The microsoil slurry supplied passes through a magnetized volume. The magnetic force gradient is formed in the magnetoresistance by matrix material (corresponding to the magnetic filter). The matrix material may be a ferromagnetic material such as stainless steel wool, steel ball or nickel foam. Under certain conditions, the box and box particles can be extracted while the box fragments pass through the magnetoresistance. Then, when the magnetic field becomes small to zero or the screen net material is removed from the magnetoresistance, magnetic fragments pour out of the screen net material. Since a more specific principle regarding the magnetic separation of the high gradient magnetic separator 140 is known in the art, a detailed description thereof will be omitted.

The heavy metal mineral removal method using the high gradient magnetic separator 140 may have a great effect as one method of soil purification. Conventional low technology and high cost soil purification methods require transportation costs and large amounts of waste and their disposal costs. Most contaminated soil purification techniques aim to reduce the amount of soil that is disposed of. However, if 90% of the soil is cleared and returned to the natural environment or recycled, the cleanup costs will be greatly reduced. Soil washing and segregation by weight are simple techniques for concentrating contaminants on large quantities of soil, making it difficult to purify soil particles below 50 μm. Therefore, heavy metal particles having a particle size of 50 μm or less are present in the environment, and heavy metal particles cannot be separated by a conventional washing method.

On the contrary, according to the high gradient magnetic separation method (HGMS), not only particles smaller than 50 μm but also particles having a size of about 0.1 μm may be separated, and may be well matched with other known physical washing methods. This high gradient magnetic separation method (HGMS), when used in conjunction with soil cleaning, can extract specific contaminants for small particle size debris with high efficiency and reduce the amount of soil disposed of.

On the other hand, after removing the heavy metal-containing mineral particles from the fine soil slurry (S140) by using the high gradient magnetic separator (140), the residual slurry from which the heavy metal-containing mineral particles are removed is 50 diameter in the cyclone 150 Separating into more or less than the soil slurry (S150). The silt crushed soil of 50 μm or less is generated by the coagulation of organic matter, clay, iron oxide, and manganese oxide.

Here, the soil slurry of 50 ㎛ or more separated from the residual slurry is dehydrated through a dehydration apparatus to be used as purified soil (S160).

In addition, for the soil slurry of less than 50 ㎛ separated from the residual slurry to perform the magnetic separation by using a high gradient magnetic separator (160) (S170). The magnetic separator 160 means the same element as the magnetic separator 140 previously used for primary magnetic separation. Of course, it is also possible to perform the primary and secondary magnetic separation using a single magnetic separator, it is also possible to arrange two separate magnetic separator to perform the magnetic separation of the primary and secondary.

Subsequently, a chemical treatment agent is added to the soil slurry of less than 50 μm through the second magnetic separation to remove and remove heavy metals eluted by the chemical treatment agent (S180). This heavy metal separation is carried out in the heavy metal reactor 170, the heavy metal component is eluted by a chemical treatment agent and then precipitated and removed. The chemical treatment agent used in the chemical reaction process, an acid treatment method using an acidic drug (ex, H ₂ SO ₄ ) can be applied, the concentration of 10-500mg / L can be used, and the non-contaminated fine soil slurry It can be used selectively when there are ready-made and ionic heavy metals.

Of course, the heavy metal treated in the heavy metal reaction step (S180) is a heavy metal elutable in the form of ions. Therefore, the heavy metal reaction step (S180) may be replaced by an ion exchange method, a coin method, a chelation method, which is a general method of removing heavy metals used in the environmental field, in addition to an acid treatment method of lowering pH using the acid solution.

Thereafter, the soil slurry from which the heavy metal is removed is dehydrated in a dewatering treatment tank 180 to be used as a purified soil (S190).

According to the heavy metal contaminated fine soil slurry purification method as described above, as a method for purifying contaminated fine soil slurry of 1 mm or less mainly composed of iron oxide mineral, manganese oxide mineral and residual minerals having a high heavy metal content, dispersion of soil particles using a dispersant treatment All types of heavy metals remaining in the fine soil slurry contaminated with heavy metals through the process (S130), the magnetic separation process (S140, S170) using the high gradient magnetic separator (140, 160), the acid treatment process (S180) using acid dissolution Can be removed. In addition, by using the high gradient magnetic separation (HGMS) method, it is possible to concentrate the heavy metal in the waste and contaminated soil, thereby reducing the waste.

In other words, intensive magnetic separation of heavy metal minerals from the soil by controlling the magnetic properties of the iron oxide and manganese oxide, which occupies more than 50% in the soil, and the heavy metal mineral of the residual form, and the magnetic field strength of the high gradient magnetic separator 140 (S140). ) To extract and remove. In addition, the remaining substitutable, water-soluble, organic heavy metals are removed by precipitation separation of heavy metals through general physicochemical treatment (S150). Therefore, micro soil slurry of less than 1mm in diameter, such as lakes, land, rivers, marine sediments, sewage, wastewater sludge, and purified sludge, remains in the heavy soil slurry contaminated with heavy metals through a dispersion process and a magnetic separation process. All heavy metals can be extracted and removed. Of course, this is only limited to heavy metal contaminants specified in the Soil Environment Conservation Act.

Hereinafter, referring to FIG. 3, an experimental example of testing purification efficiency according to an embodiment of the present invention will be described. See FIG. 3 for the process used for testing. First, foreign matters are removed after separation and washing of the particle size of the heavy metal contaminated fine soil slurry with a particle size of 1 mm or less (S210). Thereafter, the sodium (Na) -based inorganic dispersant is mixed with the heavy metal contaminated micro soil slurry of 1 mm or less to disperse the soil particles (S220). Subsequently, the dispersion-treated fine soil slurry is passed through the porous screen network in the high gradient magnetic separator 140 having a 1T magnetic field at a flow rate of 4 L / min or less to magnetically separate heavy metal-containing mineral particles from the fine soil slurry ( S230). Next, the remaining slurry after the heavy metal-containing mineral particles are separated and the particle size is separated in a hydrocyclone (50 ㎛ classification) separator (S240). Here, the soil slurry of 50㎛ or more is dewatered with a filter press (S250), the soil slurry of 50㎛ or less passes through the high gradient magnetic separator 140 once more, and then elutes the acid through an acid treatment process (dashed arrow). (S260). Thereafter, the soil slurry from which the heavy metal is removed is used as a purified soil by dehydration (S270).

Table 1 shows the content of heavy metals after the soil contaminated with heavy metals around the mine by the method of FIG. 3. Table 2 shows the content of heavy metals after the marine sediment contaminated with heavy metals by the method of FIG. 3. Table 3 shows the content of heavy metals after the soil contaminated with heavy metals of the factory site by the method of FIG. 3. For all the experiments of Tables 1 to 3, the heavy metal removal efficiency was 60% to 90%, indicating a relatively good heavy metal treatment result.

TABLE 1

TABLE 2

[Table 3]

Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary and those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

1 is a flow chart of the heavy metal contamination fine soil slurry purification method using a magnetic field according to an embodiment of the present invention,

2 is an exemplary configuration diagram for the purification method of FIG. 1;

Figure 3 is a flow chart showing an embodiment of heavy metal removal efficiency experiment using the process of the present invention.

<Description of Symbols for Main Parts of Drawings>

110: vibration dewatering screen 120: odor and organic matter removal tank

130: dispersion tank 140: magnetic separator

150: cyclone 160: magnetic separator

170: heavy metal reaction tank 180: dewatering treatment tank

Claims (11)

Dispersing the soil particles by adding an inorganic dispersant and a surfactant to the fine soil slurry; Magnetizing soil particles in the fine soil slurry to increase magnetic separation efficiency; Magnetically separating and removing heavy metal-containing mineral particles from the dispersed and magnetized fine soil slurry using a high gradient magnetic separation (HGMC) using a magnetic field; Recovering the heavy metal-containing mineral particles attached to the high gradient magnetic separator by the magnetic separation and separated from the fine soil slurry; Separating the residual slurry from which the heavy metal-containing mineral particles are removed into soil slurries of 50 µm or more in diameter and less than; Performing magnetic separation for the soil slurry of less than 50 μm using the high gradient magnetic separator secondly; Separating and removing the eluted heavy metal by adding an acidic chemical to the soil slurry of less than 50 μm after the second magnetic separation; Dewatering the soil slurry of 50 µm or more separated from the residual slurry to use as purified soil; And A method for purifying heavy metal-contaminated fine soil slurries using a magnetic field comprising the step of dehydrating the soil slurry of less than 50 μm from which the heavy metals have been removed. The method of claim 1, wherein before dispersing the soil particles, Removing foreign matter in the fine soil slurry; And The heavy metal contamination fine soil slurry purification method using a magnetic field further comprising the step of removing the odor and organic matter from the fine soil slurry from which the foreign matter is removed. delete delete The method of claim 1, wherein dispersing the soil particles, Heavy metal contamination fine soil slurry purification method using a magnetic field to disperse using the inorganic dispersant and surfactant in the concentration range of 1 ~ 10000ppm. The method of claim 1, wherein the magnetic separation step, A method for purifying heavy metal contaminated microsoil slurries using a magnetic field performed in a magnetic field ranging from 1 to 5T. delete The method of claim 1, wherein the magnetizing the soil particles, Injecting a magnetite using Fe ₃ O ₄ as the magnetizing agent in the fine soil slurry to the magnetite to act as a cross-linking between the soil particles to make the magnetism, the iron component contained in the magnetite is dissolved so that the soil It acts as a crosslinking between the particles to make the magnetism, or to dissolve the iron salt as the magnetizing agent to adjust to an alkaline state, and then to add air and increase the temperature and then into the fine soil slurry to magnetize the soil particles Method for Purifying Heavy Metal-Contaminated Microsoil Slurries Using Magnetic Field. delete delete delete

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