KR101727055B1 - Polyaluminium chloride coagulants having low basicity and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a low-basicity polyaluminum chloride coagulant for removing fluorine and a method for preparing the same. More particularly, the low-basicity polyaluminum chloride coagulant according to the present invention is obtained by a series of processes including mixing, reaction, cooling, dilution and filtration using aluminum hydroxide and concentrated hydrochloric acid as starting materials, and a process of controlling basicity by adding an additional low-basicity inducing agent. Accordingly, the low-basicity polyaluminum chloride coagulant has excellent aluminum oxide content and excellent physical properties including, pH, basicity, specific gravity and turbidity, is excellent in terms of precipitation (turbidity) and sludge generation and shows an excellent ability of removing fluorine-containing ingredients in water to be treated, and thus is particularly suitable for applying to plant waste water discharged from a system of producing semiconductors or other products.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an aluminum chloride based polymer flocculant and a method for producing the same,

The present invention relates to a low-salt, low chloride aluminum chloride-based polymer flocculant for removing fluorine and a process for producing the same. More particularly, the present invention relates to a process for producing a low- And an additional low-salt-inducing agent to improve the physical properties such as content, pH, basicity, specific gravity and turbidity of aluminum oxide, and good sedimentation (turbidity) and sludge generation amount, And more particularly to a low-salt airborne aluminum chloride-based polymer flocculant suitable for application to factory wastewater discharged from a facility for producing products such as semiconductors and a method for producing the same.

In general, chemicals such as coagulants and flocculants are added to remove fine clay, organics, bacteria, algae, colloidal materials that are not removed by conventional precipitation treatment in raw water treatment To remove colloidal components. These coagulation processes are one of the most important processes in the treatment of water and wastewater, and inorganic coagulants such as aluminum (aluminum sulfate) and iron salts (ferrous sulfate, ferric chloride) have been used for a long time.

Until now, such low molecular weight inorganic flocculants have a merit that they are relatively inexpensive. However, they are disadvantageous in that they have insufficient ability to remove turbidity and suspended substances due to a small molecular particle size in an aqueous solution and a large decrease in pH of the treated water. Aluminum sulphate, which is widely used in Korea, is inexpensive and does not cause corrosive damage compared to iron salt based coagulant. Therefore, the amount of aluminum sulfate used varies depending on the water quality of raw water. When turbidity is temporarily increased in high season such as rainy season, The processing ability is remarkably deteriorated, and the increase of residual aluminum caused by overuse of the aluminum has serious problems such as causing Alzheimer's disease.

In recent years, poly (aluminum chloride) (PAC) has been developed to replace the above-mentioned low molecular weight inorganic flocculant to improve the above disadvantages. The polychlorinated aluminum is a polybasic inorganic flocculant, and since it is a coordination substance having an aqua complex ion in an aqueous solution, -OH) crosslinks to form a polynuclear complex and the nucleus is increased to form a macerated inorganic polymer compound. In addition, aluminum polychloride has a higher rate of floc formation and sedimentation rate than aluminum sulfate, requires almost no alkaline preparation and coagulation aid, has a small amount of pH, . It has an excellent turbidity improving effect of 1.2 to 5 times with respect to both low turbidity and high turbidity, and has an advantage of good flocculation effect even at low temperature.

Such polychlorinated aluminum is generally used by mixing and reacting 2 moles of aluminum hydroxide (Al (OH) ₃ ) with hydrochloric acid and then diluting with water.

_{2Al (OH) 3 + 3HCl →} [Al 2 (OH) 3 Cl 3] n + 3H 2 O

However, the basicity of poly (aluminum chloride) is an important characteristic closely related to composition, structure, physicochemical properties, coagulation effect, storage stability, etc., and the equivalence of aluminum (Al) -OH) equivalents.

In addition to the basicity, the polychlorinated aluminum flocculant has various properties to be equipped such as flocculation efficiency, storage stability, sludge and residual aluminum generation, algae and organic removal efficiency, and phosphorus removal efficiency. There is a growing demand for an efficient and simple method for producing a coagulant of a polymer. Also, there is a need for a regulator or an inducer capable of efficiently controlling or controlling the characteristics of the product when the characteristics such as the basicity do not meet the intended level and are too much or too little, .

Korean Patent No. 10-0221977 (published on September 15, 1999, 'Process for producing inorganic polymer flocculant containing aluminum chloride as a main component)

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a process for the production of an aluminum- (PH), basicity, specific gravity, and turbidity, and is excellent in sedimentation (turbidity), sludge generation amount, etc., and is excellent in removing fluorine components in the water to be treated. The present invention provides a flocculant for fluorine removal suitable for application to factory wastewater discharged from a facility for producing a product and a method for producing the same.

(A) an aqueous solution of hydrochloric acid (HCl) in a concentration of 35% by weight or more based on 100 parts by weight of aluminum hydroxide (Al (OH) ₃ ) Mixing the components; (b) reacting the mixed aluminum hydroxide and aqueous hydrochloric acid solution for 4 to 10 hours; (c) cooling the reaction until the temperature is between 100 and 120 < 0 >C; (d) adding diluted water to the reactant, stirring the reactant, and filtering the diluted reactant; And (e) adding a low-salt inducing agent to the filtered reactant to adjust the basicity to 0.1 to 35%. The present invention also provides a method for producing a low-salt-reducing aluminum chloride-based polymer flocculant.

At this time, in step (e), the low-salt inducing agent may be at least one selected from the group consisting of hydrochloric acid (HCl), aluminum sulfate, and chloride of a Group 2A metal element.

On the other hand, according to another embodiment of the present invention to achieve the object as described above (a) aluminum hydroxide (Al (OH) ₃₎ hydrochloric acid (HCl) aqueous solution of 35% or more by weight based on 100 parts by weight of concentration from 220 to 260 parts by weight; (b) reacting the mixed aluminum hydroxide and hydrochloric acid aqueous solution at a pressure of 4.5 to 6.0 kg / cm ² and a temperature of 135 to 165 ° C for 4 to 10 hours; (c) cooling the reaction until the temperature is between 100 and 120 < 0 >C; (d) adding diluted water to the reactant so that the specific gravity at room temperature (20 ° C) is 1.19 to 1.22, stirring the reactant, and filtering the reactant so that the turbidity of the diluted reactant is maintained at 5 NTU or less; The content of is produced, including the (a) ~ the coagulant is aluminum oxide (Al ₂ O ₃₎ prepared in the step (e); and (e) adding a low salt airway inducing agent to the filtered reaction step of adjusting the basicity Is 5 to 25% by weight, and the basicity is 0.1 to 35%. The present invention provides a low-salt-reducing aluminum chloride-based polymer flocculant for removing fluorine.

As described above, the low-salt-reducing aluminum chloride-based polymer flocculant of the present invention and the method for producing the same are excellent in physical properties such as content of aluminum oxide, pH, basicity, specific gravity and turbidity and have excellent flocculation efficiency, storage stability, The excellent aluminum chloride polymer flocculant can be easily manufactured through a simple and efficient method. When it is necessary to control the product to conform to the product standard such as basicity, or to upgrade or downgrade the product standard, There are advantages that can be adjusted.

In addition, it is possible to effectively treat wastewater discharged from various product manufacturing plants such as semiconductors through the flocculant for fluorine removal of the present invention, which has a pH value suitable for the decomposition reaction of fluorine and has a low sludge generation amount and turbidity and a high fluorine removal rate .

1 is a photograph of a comparative experiment (sedimentation experiment) performed between a preferred embodiment of the present invention and a comparative example.

Hereinafter, embodiments of the low-salt-reducing aluminum chloride-based polymer flocculant for removing fluorine of the present invention and a method for producing the same will be described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. shall.

Throughout this specification, when a member is " on " another member, this includes not only when the member is in contact with another member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including" an element, it is understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

In each step, the identification code is used for convenience of explanation, and the identification code does not describe the order of the steps, and each step may be performed differently from the stated order unless clearly specified in the context. have. That is, each of the steps may be performed in the same order as described, or may be performed substantially concurrently or in the reverse order.

The method for preparing the low-salt-reducing aluminum chloride-based polymer flocculant of the present invention can be largely composed of a mixing step, a reaction step, a cooling step, a stirring / filtering step, and a basicity adjusting step.

First, in the mixing step, aluminum hydroxide (Al (OH) ₃ ) and a concentrated hydrochloric acid (HCl) aqueous solution having a concentration of 35 wt% or more are metered and mixed. The process of inspecting the material specifications of aluminum hydroxide and concentrated hydrochloric acid added prior to mixing can be preceded. Specifically, each material is sampled three times to determine whether the appearance of the aluminum hydroxide is over the limit sample, the content of Al ₂ O ₃ is 55 wt% or more, the content of iron (Fe) is 0.01 wt% 10.0 wt% or less, and whether or not the appearance of the concentrated hydrochloric acid is more than the limit sample, the concentration is more than 35 wt%, the iron content is less than 0.002 wt%, the specific gravity is 1.18 or more You can check.

When the material specification inspection is completed, each material is weighed and put into the reaction tank and mixed. The added amount is preferably 220 to 260 parts by weight of concentrated hydrochloric acid aqueous solution when 100 parts by weight of aluminum hydroxide is used as a standard. Equipment used in the mixing step is preferably a 2m ³ specifications of sual storage hopper, 3m ³ specifications of sual weighing tank (load cell), 20m ³ and 30m ³ specifications of hydrochloric acid storage tank, of 50A standard HCl flow meter, the reactor of 8m ³ standard 3, an absorption tower of 60 m ³ / min, and the like.

After inspecting each part of the equipment, the quantity of aluminum hydroxide to be input to the load cell indicator is input, preferably 2,700 ± 100 kg. Aluminum hydroxide is then put into a hopper for storage by a forklift and the loaded raw material is transferred to a water metering hopper by a belt conveyor. Then, the absorber is operated, and the quantity of hydrochloric acid is checked with a hydrochloric acid flow meter, and it is confirmed whether it is preferably 6,500 ± 200 kg.

Hydrochloric acid is added to the reaction tank through a hydrochloric acid flow meter. When the amount of hydrochloric acid is 2/3 or more, the reaction tank switch of the aluminum hydroxide measuring hopper is turned on, and aluminum hydroxide is introduced into the reaction tank. At this time, it is preferable that the stirrer of the reaction tank is also operated to uniformly mix the raw materials. Then turn off the screw conveyor switch of the weighing hopper and lock the hydrochloric acid inlet valve. When all of the raw materials have been transferred, each valve is closed and the absorber is stopped.

Next, the reaction step is a step of reacting the charged and mixed aluminum hydroxide and hydrochloric acid aqueous solution under high temperature and high pressure conditions. Equipment to be used in the reaction process is a such of the three reactors of 8m ³ standard, 3T / H and 10kg / cm ² standard of the steam boiler, 15HP standard compressors. The reaction is preferably carried out at a pressure of 4.5 to 6.0 kg / cm ² and at a temperature of 135 to 165 ° C for 4 to 10 hours.

Specifically, when the steam jacket is slowly opened in the reaction tank jacket to slowly heat the reaction tank, the tank jacket pressure is 4.5 to 6.0 kg / cm ² , and when the temperature in the tank is 135 to 165 ° C, the reaction time is 4 to 10 hours .

Next, it is a process of cooling until the temperature of the reactant becomes 100 to 120 캜. Specifically, when the reaction time has elapsed, the steam valve is shut off, the steam in the jacket is discharged, the scraper is operated, and the steam in the tank is discharged to gradually cool until the temperature of the reactant becomes 100 to 120 ° C. When cooling is completed, the reaction liquid discharge valve is opened and the reaction liquid is transferred to the storage tank. When the transfer of the reaction liquid is completed, the reactor jacket is ventilated to cool the inside of the tank, and stirring of the reaction liquid transferred to the storage tank is started.

Next, dilute water is added to the reactant and stirred to adjust the concentration. It is preferable that the dilution water is introduced into the process so that the specific gravity at room temperature (20 ° C) is 1.19 to 1.22.

Specifically, the process is to adjust the concentration of the product so that the final product meets the target quality and to stabilize it as a uniform product. Industrial water (diluted water) is used in this process. When the semi-finished product is transferred to the concentration adjusting tank, dilute water is added while the agitator is operated. The amount to be added is preferably 6,600 ± 200 kg. The specific gravity of the product is monitored in real time while the diluted water is added, and the specific gravity is controlled to be 1.19 to 1.22 under the room temperature condition. When the dilution water is supplied, the operation of the agitator is stopped and the filtrate is transferred through the discharge valve. At this time, it may be directly transferred to the filtration unit, but it may be passed through a tank for intermediate inspection or an inspection device may be installed in the middle of the transport pipe to collect the product sample after concentration control, and then to check the specific gravity value.

Next, it is preferable to filtrate the diluted reaction product so that the turbidity is maintained at 5 NTU or less. For the filtration process, a facility such as a polypropylene (PP) bag filter of 24 m ³ / h standard can be used.

Specifically, the filtration (air) pump valve connected to the filtration tank is opened and a filtration pressure of 1.0 kg / cm ² is preferably applied through a pressure gauge. The turbidity at the inlet of the storage tank is monitored and whether the turbidity is maintained below 5 NTU is monitored in real time to adjust the air pump pressure according to the degree of turbidity. If the pressure of the air pump tends to rise abnormally, the filter cloth should be replaced.

In the process of transferring the filtered product to the inspection tank, some samples may be collected to check the turbidity. In addition, samples of the product transferred to the inspection tank can be sampled to check the specifications of the polymer flocculant product. It is possible to check whether the content of aluminum oxide (Al ₂ O ₃ ) is 10 to 11% by weight, whether the pH is 3.5 to 5.0, the basicity is 45 to 60%, the specific gravity is 1.19 or more. When product specification inspection is completed, it is transferred to the storage tank.

Next, a basicity control step of adding a low-salt inducing agent to the filtered reactant is performed. The step of controlling the basicity is a step of lowering the basicity of the product by using various low-salt inducing agents such as hydrochloric acid, aluminum sulfate and chloride of the Group 2A metal element to make a low-salt air-entraining agent, and a low- .

Hereinafter, examples of low-salt inducing agents that can be used and put into the step of controlling the basicity of the present invention will be described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. shall.

[Example A1] Low salt inducing agent: hydrochloric acid (HCl)

The basicity of the final product can be effectively lowered by adding hydrochloric acid to the aluminum chloride polymer flocculant product produced through the filtration step. In this case, the reaction can be performed at a temperature of 40 to 80 ° C. for 1 to 5 hours. After the reaction, the basicity can be lowered to 10 to 20% at maximum, and the content of aluminum oxide can be adjusted to 9 to 11.2% at maximum. As a result, it is possible to increase flocculation performance and storage stability, minimize the generation of sludge and residual aluminum, and improve algae and organic matter removal performance.

[Example A2] Low salt inducing agent: aluminum sulfate

The basicity of the final product can be effectively lowered by adding aluminum sulfate to the aluminum chloride polymer flocculant product produced through the filtration step. A preferable composition of the aluminum sulfate used may be an aluminum oxide content of 5 to 17% and a sulfate ion (SO 4 ^2- ) content of 10 to 50%. The amount to be added is preferably about 1 to 5 parts by weight based on 100 parts by weight of the initial aluminum hydroxide, and it is preferable to add water in an amount of 35 to 40 parts by weight.

After the addition of the aluminum sulfate, the reaction can be carried out at a temperature of 30 to 80 ° C. at a rate of 35 to 90 rpm and for a reaction time of about 0.5 to 3 hours, thereby effectively binding a sulfate ion to the aluminum chloride and thereby stabilizing the aluminum chloride polymer flocculant Can be manufactured.

By introducing the low-salt inducing agent according to this embodiment, the aluminum oxide content of the final product can be adjusted to about 9 to 15 wt%, the basicity can be adjusted to about 0.1 to 35%, and the content of sulfate ion can be adjusted to 0.001 to 3.5 wt% have. This can increase phosphorus removal efficiency and minimize sludge generation.

[Example A3] Low salt inducing agent: Chloride of Group 2A metal element

The basicity of the final product can be effectively lowered by adding a chloride of a Group 2A metal element to the aluminum chloride polymer flocculant product produced through the filtration step. Preferred examples of the Group 2A metal element include magnesium (Mg) and calcium (Ca).

When the low salt inducing agent according to the present invention is added, the formula of the final polymer flocculant product is in the form of Al ₂ M _A (OH) _B Cl _C , where 6 + 2A = B + C, 0.08? A? 0.13, and 0.01? B? 0.95.

The final product can be adjusted to a maximum aluminum content of 5 to 25% by weight and a basicity of up to 16%, which reduces the reaction of phosphorus with respect to aluminum equivalents upon phosphorus removal, The problem of the high basic coagulant, which has a high weight, can be solved.

Meanwhile, according to another preferred embodiment of the present invention, when the standards such as the aluminum oxide content, the pH, and the basicity of the final product are not satisfied with the desired standard, or the basicity is increased as needed, Can be performed.

Specifically, the additional control step can increase the basicity of the final product by injecting a high-salt inducing agent. According to a preferred embodiment, the high salt inducing agent may be at least one selected from the group consisting of sodium hydroxide (NaOH), hydroxide of rare earth element (Re (OH) ₃ ) and aluminum silicate.

Hereinafter, embodiments of high salt inducing agents that can be used and put into the further control step of the present invention will be described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. shall.

[Example B1] High salt inducing agent: sodium hydroxide (NaOH)

The basicity of the final product can be effectively increased by adding sodium hydroxide (NaOH) to the aluminum chloride polymer flocculant product prepared through the basicity control step.

Specifically, 15 to 25 parts by weight of sodium hydroxide, 15 to 25 parts by weight of water and 1 to 5 parts by weight of magnesium hydroxide (Mg (OH) ₂ ) are added sequentially, based on 100 parts by weight of the filtered product, Lt; 0 > C for 6 to 10 hours.

Through this process, to the basicity of the final product up to 60-70%, and to control the content of Al ₂ O ₃ up to 10% to 15%, to increase the agglomeration performance and storage stability is also effective in minimizing the sludge volume and the residual aluminum .

[Example B2] High salt inducing agent: Rare earth hydroxide (Re (OH) ₃ )

The basicity of the final product can be effectively increased by addition of rare earth hydroxide (Re (OH) ₃ ) to the aluminum chloride polymer flocculant product prepared through the basicity control step. Preferred examples of the rare earth element include lanthanum (La), cerium (Ce), neodymium (Nd), and samarium (Sm).

When the rare earth hydroxide is introduced as a high salt-inducing agent, it is preferable to pre-treat the product after the filtration process with a sulfate. Specifically, 1 to 20 parts by weight of a sulfate having a sulfate ion content of 50 to 80% by weight based on 100 parts by weight of the product is reacted at a temperature of 20 to 60 ° C for 1 to 5 hours, and then 50 To 90% by weight of rare earth hydroxides is preferably added in an amount of 0.1 to 10 parts by weight, and the reaction is preferably carried out at 20 to 60 ° C for 0.5 to 7 hours. Preferable examples of the sulfate used include calcium sulfate (CaSO ₄ ), magnesium sulfate (MgSO ₄ ), iron sulfate (FeSO ₄ ), zinc sulfate (ZnSO ₄ ) and potassium sulfate (K ₂ SO ₄ ).

Further, it is preferable to carry out an additional aging process even after reacting the rare earth hydroxide. Specifically, the product can be stabilized by aging for 1 to 5 hours at 30 to 60 ° C after the reaction. The powder size of the rare earth hydroxide to be used is preferably in the range of 0.1 to 10 μm, and the basicity of the final product can be adjusted up to 50 to 70%.

In this embodiment, the coagulation efficiency and the storage stability can be improved by using a relatively small amount of rare earths, which are natural minerals, and the basicity can be effectively increased through the synergy effect of the sulfate and the rare earth.

[Example B3] High salt inducing agent: aluminum silicate

It is possible to effectively increase the basicity of the final product by further adding aluminum silicate to the aluminum chloride polymer flocculant product prepared through the basicity control step.

One preferred embodiment of the aluminum silicate used is a compound in the form of Na _A Al _B (SiO ₂ ) _{C, where 1? A? 4} , _{1 B 4} and 1 _{C 4} The content of Al ₂ O ₃ may be 10 to 28% by weight, and the content of Na ₂ O may be 10 to 25% by weight.

The aluminum silicate may be added to the coagulant product and reacted at a temperature of 20 to 80 ° C for 1 to 10 hours. At this time, stirring is carried out through a homogenization reactor capable of maintaining the stirring speed at 500 to 30,000 rpm It is good. Further, as an additional post-treatment after the reaction, it is preferable to carry out the stabilization process at a temperature of 40 to 100 DEG C for 1 to 15 hours.

This makes it possible to control the content of aluminum oxide in the final product up to 5 to 25% by weight and the basicity to 50 to 90% in maximum, thereby effectively producing a polymer flocculant having a high salt resistance even with a relatively small amount of high salt- And storage stability can be increased.

On the other hand, the aluminum silicate according to this embodiment can be produced through the following preferred embodiments. (Al (OH) ₃ , Al ₂ O ₃ concentration 50 to 70%) 15 to 50% by weight, sodium hydroxide (NaOH, Na ₂ O concentration 30 to 50% 0.01 to 10% by weight of a non-silicate, and the balance water, and reacting the mixture at 80 to 160 ° C for 0.5 to 10 hours.

Hereinafter, comparative experimental examples of the low-salt-reducing aluminum chloride-based coagulant of the present invention will be described. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. shall.

[Experimental example] Comparative experiment of flocculant performance

A mixture of 16 wt% hydrochloric acid (HCl) at a concentration of 35 wt%, which is a low salt inducing agent, and 22 wt% of diluted water, were mixed with 62 wt% of an aluminum chloride polymer flocculant (PAC) having a content of aluminum oxide 16.5 wt% Sample 2 (aluminum oxide content 10 wt%, basicity 45%) and sample 3 (aluminum oxide content 17 wt%, basicity 38%) are prepared as a comparative example according to a preferred embodiment of the present invention.

The initial concentration of fluorine (fluorine) in the supernatant of the settling tank to be treated is measured. Then, each of the three beakers is charged with 1,000 ml of the settling tank supernatant and 10 ml of each of the samples 1 to 3, and the mixture is stirred for 90 minutes. After measuring the pH value of the mixed solution in the beaker, 2.5 ml of the polymer is injected into each beaker, followed by rapid stirring for 1 minute and slow stirring for 15 minutes. Thereafter, it is left to stand for 20 to 30 minutes, and the state of precipitation is checked, and the final fluorine removal rate is measured. The results of the experiment are summarized in Table 1 below.

Summary of experiment results
TF content in the precipitation equilibrium (ppm)
249
division
Sample 1
Sample 2
Sample 3
pH value
2.47
4.38
3.81
Turbidity (NTU)
1.8
2.5
3.2
Sludge (v / v%)
20
26
24
Fluorine Removal Rate (%)
86
70
68

Considering that the pH value of the supernatant of the precipitation tank added with Samples 1 to 3 was the lowest at 2.47 in the case of Sample 1 according to the present invention and that the optimum pH of the decomposition reaction of fluorine was 4 or less, It can be seen that the effect as the flocculant for removing fluorine is dominant. On the other hand, Sample 1, which is an embodiment of the present invention, is superior to Samples 2 and 3 which are comparative examples in terms of precipitation (turbidity) and sludge generation index which are important factors in wastewater treatment, and the fluorine removal rate is also excellent. Referring to FIG. 1, it can be seen that the amount of sludge produced in Sample 1, which is an embodiment of the present invention, is the smallest.

In particular, the present invention relates to a process for treating plant wastewater discharged from industrial equipment of various electronic products such as semiconductors, which is most important to minimize the high removal efficiency of fluorine components such as heavy fluorine and turbidity and sludge generation, Can be effectively used.

The present invention is not limited to the above-described specific embodiment and description, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention as claimed in the claims. And such modifications are within the scope of protection of the present invention.

Claims (3)

(a) mixing 220 to 260 parts by weight of a hydrochloric acid (HCl) aqueous solution having a concentration of 35% by weight or more based on 100 parts by weight of aluminum hydroxide (Al (OH) ₃ );
(b) reacting the mixed aluminum hydroxide and hydrochloric acid aqueous solution at a pressure of 4.5 to 6.0 kg / cm ² and a temperature of 135 to 165 ° C for 4 to 10 hours;
(c) cooling the reaction until the temperature is between 100 and 120 < 0 >C;
(d) adding diluted water to the reaction mixture so that the specific gravity at room temperature (20 ° C) is 1.19 to 1.22, stirring the mixture, and filtering the diluted reaction product so that the turbidity is maintained at 5 NTU or less; And
(e) adding a low-salt inducing agent to the filtered reactant to adjust the basicity to 0.1 to 35%;
/ RTI >
In the step (e), the low-salt-inducing agent is aluminum sulfate having an aluminum oxide (Al ₂ O ₃ ) content of 5 to 17 wt% and a sulfate ion (SO ₄ ^2- ) content of 10 to 50 wt% The sulfuric acid salt is added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the aluminum hydroxide in the step (a), and 35 to 40 parts by weight of water based on 100 parts by weight of the aluminum hydroxide in the step (a) And the mixture is reacted for 0.5 to 3 hours while stirring at 30 to 80 ° C after the addition. delete (a) mixing 220 to 260 parts by weight of a hydrochloric acid (HCl) aqueous solution having a concentration of 35% by weight or more based on 100 parts by weight of aluminum hydroxide (Al (OH) ₃ );
(b) reacting the mixed aluminum hydroxide and hydrochloric acid aqueous solution at a pressure of 4.5 to 6.0 kg / cm ² and a temperature of 135 to 165 ° C for 4 to 10 hours;
(c) cooling the reaction until the temperature is between 100 and 120 < 0 >C;
(d) adding diluted water to the reaction mixture so that the specific gravity at room temperature (20 ° C) is 1.19 to 1.22, stirring the mixture, and filtering the diluted reaction product so that the turbidity is maintained at 5 NTU or less; And
(e) adding a low-salt inducing agent to the filtered reactant to adjust the basicity,
In the step (e), the low-salt-inducing agent is aluminum sulfate having an aluminum oxide (Al ₂ O ₃ ) content of 5 to 17 wt% and a sulfate ion (SO ₄ ^2- ) content of 10 to 50 wt% The sulfuric acid salt is added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the aluminum hydroxide in the step (a), and 35 to 40 parts by weight of water based on 100 parts by weight of the aluminum hydroxide in the step (a) After the addition, the mixture was reacted at 30 to 80 ° C for 0.5 to 3 hours while stirring,
The flocculant prepared by the steps (a) to (e) has a content of aluminum oxide (Al ₂ O ₃ ) of 9 to 15% by weight, a basicity of 0.1 to 35%, a content of sulfate ions of 0.001 to 3.5 % By weight based on the total weight of the aluminum chloride-based polymer flocculant.

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