KR101334861B1 - Method for manufacturing porous pellet type water treatment agent - Google Patents

Abstract

The present invention relates to a production method of a porous pellet type water treatment agent which can produce the porous pellet type water treatment agent without neutralizing red mud. The present invention comprises the following steps: (S1) plasticizing red mud at 100-900 for drying and preprocessing; (S2) mixing ordinary Portland cement and aluminum flake with the red mud preprocessed from step (S1); (S3) adding water into the mixture in step (S2); (S4) molding the mixture obtained in step (S3); (S5) curing the molded product with pores which is obtained in step (S4) underwater; (S6) drying the product which is cured underwater in step (S5); and (S7) crushing the dried product in step (S6) into a pellet form. [Reference numerals] (S1) Red mud preprocessing step;(S2) First mixing step;(S3) Second mixing step;(S4) Hole formation and block cutting;(S5) Water curing step;(S6) Drying step;(S7) Pulverizing step (pellet size)

Description

Method for Manufacturing Porous Pellet Type Water Treatment Agent {Method for Manufacturing Porous Pellet Type Water Treatment Agent}

The present invention relates to a method for producing a porous pellet type water treatment agent capable of highly treating total phosphorus (T-P) and metals contained in wastewater or seawater.

In general, phosphorus (phosphate), which is the main cause of eutrophication and the limiting substance of algae growth, has been mainly biological treatment methods or chemical treatment methods using flocculants.

However, biological processes are difficult to operate, and it is not easy to ensure continuous and stable effluent quality.

Another electrolysis / aggregation phosphorus removal technology is one of the technologies that can take advantage of the chemical removal technology and solve the disadvantages of the chemical precipitation method or electrode corrosion.

The shells are used for exhaust gas removal, acid soil improver, heavy metal adsorption, and high concentration of phosphorus removal. However, calcium carbonate, which occupies most of the shells of oysters, has a large amount of sludge generation when applied to water treatment, and contains a large amount of organic and inorganic materials. Because of the problem, there is a problem that must go through an appropriate firing process.

In addition, crystallization dephosphorization is one of the methods of removing phosphate from sewage that is practical and showing good results, but it is possible to treat ordinary sewage secondary treated water. Silver differs depending on the set pH, calcium concentration, water temperature, disturbance in raw water, contact time, and the performance of the contact materials. Should be removed by secondary functions such as filtration.

The coarse dephosphorization method adjusts pH by adding magnesium to sewage and recovers phosphorus as a crystal of magnesium ammonia (MAP), but there is a problem in that it is not suitable for treating effluent.

Currently, soluble phosphorus is generally removed by precipitation of soluble phosphorus with one or more metal ions such as Al (aluminum), Fe (iron) or calcium (Ca), which are precipitated with insoluble metal phosphates. Difficulty in overuse of medicine and disposal of sludge treatment.

Therefore, it is required to quickly remove total phosphorus and dissolved inorganic substances in the discharged water at the same time to a very small amount and to develop a new treatment technology that is easy to maintain and economical without using chemicals.

The present invention is capable of highly treating total phosphorus and metals contained in sewage / wastewater or seawater by using a simple manufacturing process using red mud, which is a general waste of workplaces, generated during bauxite refining. The present invention provides a method for preparing a porous pellet type water treatment agent.

Accordingly, the present invention is a first preferred embodiment, (S1) drying the red mud (red mud) pre-treatment; (S2) a first mixing step of mixing portland cement (Ordinary Portland Cement, OPC) and aluminum flakes in the red mud pretreated in the step S1; (S3) a second mixing step of mixing water with the mixture mixed in the step (S2); (S4) molding the mixture obtained in the step (S3); (S5) curing the molding in which the pores obtained in the step (S4) are formed in water; (S6) drying the molding cured in the water in the step (S5); And (S7) provides a method for producing a porous pellet-type water treatment agent comprising the step of crushing the molded product dried in the step (S6) in the form of pellets.

The red mud in the step (S1) according to the embodiment may be pH 10 or more, and a particle size of 6 to 10 μm.

Drying of the step (S1) according to the embodiment may be performed at 100 ~ 900 ℃.

Step (S2) according to the embodiment may be to mix 40 to 60 parts by weight of Portland cement and 0.1 to 0.3 parts by weight of aluminum flakes with respect to 100 parts by weight of red mud pretreated in step (S1).

Step (S3) according to the above embodiment dissolves 5-20 parts by weight of MgCl ₂ , 3-6 parts by weight of CaCl ₂ and 0.2-0.4 parts by weight of FeSO ₄ in the mixture mixed in step (S2), based on 100 parts by weight of water. The mixed water may be mixed to mix.

The method for producing a porous pellet-type water treatment agent according to the embodiment may further include sealing to maintain the pH of the porous pellet-type water treatment agent formed in the step (S8).

The pH of the porous pellet-type water treatment agent according to the embodiment may be 9 to 12.

According to the present invention, the porous pellet-type water treatment agent can be prepared without neutralizing the strong alkaline red mud, which is a general waste of the workplace generated in the bauxite purification process.

1 is a flow chart showing a process of the method for producing a porous pellet type water treatment agent according to the present invention.
Figure 2 shows a porous pellet-type water treatment agent prepared by the method for producing a porous pellet-type water treatment agent according to the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for producing a porous pellet-type water treatment agent using strongly alkaline red mud, which is a general waste of the workplace generated during the bauxite purification process.

(S1) drying and pretreating red mud; (S2) a first mixing step of mixing portland cement (Ordinary Portland Cement, OPC) and aluminum flakes in the red mud pretreated in the step S1; (S3) a second mixing step of mixing water with the mixture mixed in the step (S2); (S4) molding the mixture obtained in the step (S3); (S5) curing the molding in which the pores obtained in the step (S4) are formed in water; (S6) drying the molding cured in the water in the step (S5); And (S7) relates to a method for producing a porous pellet type water treatment agent, comprising the step of crushing the molded product dried in the step (S6) in the form of pellets (Fig. 1 and 2).

In the present invention, step (S1) is a step of drying and pretreating red mud.

The red mud may have a pH of 10 or more and a particle size of 6 to 10 μm. In other words, red mud, a general waste generated at the bauxite refining process, contains about 50% of water and is mixed in various particle sizes. When the porous pellet-type water treatment agent is made using the particle size, the manufacturing process is easy, and the water treatment agent has excellent water treatment efficiency. Therefore, it is preferable to use red mud having a pH of 10 or more and a particle size of 6 to 10 μm.

In addition, the red mud is Fe ₂ O ₃ (25 to 45% by weight), Al ₂ O ₃ (15 to 25% by weight), SiO ₂ (15 to 21% by weight), Na ₂ O (11 to 13%), TiO ₂ (4-10%), CaO (3-5%), SO ₃ (0.3-0.4%), ZrO ₂ (0.3-0.35% by weight), P ₂ O ₅ (0.2-0.21%), Cr ₂ O ₃ (0.1 to 0.11%) and K ₂ O (0.04 to 0.05%) may be included.

The drying of the red mud can be carried out by firing at 100 ~ 900 ℃, if the firing temperature is less than 100 ℃ can not evaporate the crystal water of the mineral constituting the red mud can not be dried as desired, the firing temperature is Above 900 ° C, useful minerals such as Hematite, Gibbsite, and Boehmite can cause minor phase transitions.

In the case of dried red mud, the water content may be up to 10% by weight, so that the manufacturing process may be easy and the water treatment efficiency of the prepared water treatment agent may be more excellent.

In the present invention, step (S2) is a first mixing step of mixing portland cement (Ordinary Portland Cement, OPC) and aluminum flake (aluminum flake) to the red mud pretreated in the step (S1).

Portland cement serves to enhance the strength of the porous pellet-type water treatment agent, the content may be 40 to 60 parts by weight based on 100 parts by weight of the pretreated red mud. If the content of the portland cement is less than 40 parts by weight, the strength of the porous pellet-type water treatment agent is lowered. If it is more than 60 parts by weight, the strength of the porous pellet-type water treatment agent is increased but pores are not well formed.

The aluminum flakes serve to form pores in the porous pellet-type water treatment agent, and the content thereof may be 0.1 to 0.3 parts by weight based on 100 parts by weight of the pretreated red mud. If the content of the aluminum flakes is less than 0.1 parts by weight, pores are not well formed. If the amount of the aluminum flakes is more than 0.3 parts by weight, the pores are appropriately formed, but the strength may be reduced.

In the present invention, step (S3) is a second mixing step of mixing water in the mixture mixed in the step (S2).

By mixing 40 parts by weight of water with the mixture 100 mixed in the step (S2), the mixture can be made into a slurry state to facilitate molding in the step (S4).

At this time, instead of the water may be used mixed water dissolved in 5 to 20 parts by weight of MgCl ₂ , 3 to 6 parts by weight of CaCl ₂ and 0.2 to 0.4 parts by weight of FeSO ₄ with respect to 100 parts by weight of water, by using the mixed water , The total removal efficiency of the prepared porous pellet-type water treatment agent can be improved.

In the present invention, step (S4) is a step of molding the mixture obtained in the step (S3).

In the step (S4), the mixture of the slurry state obtained in the step (S3) is transferred to the molding die, the gas can be ejected and expanded from the mixture to form a molded article formed with pores.

After transferring the mixture obtained in the step (S3) to the mold, after 10 to 24 hours to separate the mold, and cut into a block (block) can be obtained in the form of a block.

In the present invention, step (S5) is a step of curing the molding formed in the pores obtained in the step (S4) in water, in order to increase the strength of the molding obtained in the step (S4) for 1 to 3 days Can be cured by dipping in water.

In the present invention, step (S6) is a step of drying the molded article in the water in the step (S5), it may be air dried or dried with a dryer for 1 to 2 days using the wind. In the step (S5), the molding cured in water is cement-mixed with red mud, and in some cases, a mixed water including MgCl ₂ , CaCl _2, and FeSO ₄ may be mixed, so that it may be exposed to direct sunlight or higher than 100 ° C. If it is dried at, the block is cracked, the strength is reduced, and the product recovery rate is low, so it can be air-dried or dried by a dryer.

In the present invention, step (S7) is a step of crushing the molded product dried in the step (S6) in the form of pellets.

The molded product dried in step (S6) can be prepared in pellet form, and can be shredded to a size of 5 to 20 mm for ease of use.

In the present invention, step (S8) is a step of sealing to maintain the pH of the porous pellet-type water treatment agent formed in the step (S7).

The porous pellet-type water treatment agent prepared in the present invention needs to be maintained at pH 9-12 to improve the removal efficiency of total phosphorus and metal contained in wastewater or seawater.

Therefore, in order to maintain the pH of the porous pellet-type water treatment agent, the finally produced porous pellet water treatment agent may be stored and used in a bag containing a built-in vinyl to prevent air permeation or in a closed space until it is applied on site.

The porous pellet-type water treatment agent prepared by the method of preparing the porous pellet-type water treatment agent prepared by the above-described manufacturing method has a plurality of pores, has a specific gravity of 0.4-0.5, and has a round or keratin shape. It may be, and it is not easily broken, and there is no loosening phenomenon even if it is put in water or permeated into a column.

In addition, by removing the phosphorus (P) that causes eutrophication using the porous pellet-type water treatment agent, not only can reduce the pollutant load caused by phosphorus, there is also an effect that can remove a small amount of dissolved inorganic material at the same time.

The present invention will now be described in detail with reference to specific examples. However, it should be understood that the present invention is not limited to these embodiments and that various changes and modifications may be made therein without departing from the scope of the present invention. Of course.

≪ Example 1 >

Example 1-1

15 kg of red mud dried by firing at 800 ° C., 7.2 kg of OPC and 32 g of aluminum flake were mixed for 5 minutes to obtain a mixture.

14.5 L of mixed water in which MgCl ₂ , CaCl ₂ and FeSO ₄ were dissolved was introduced into the mixture, and mixed for about 5 minutes to make a slurry. At this time, the mixed water is 10 parts by weight of MgCl ₂ , 5 parts by weight of CaCl ₂ , and 0.3 parts by weight of FeSO _{4 based} on 100 parts by weight of water.

After the slurry mixture was transferred to the mold, 24 hours after the gas ejection and expansion reaction, the mold was separated, and the separated molding was cut into blocks.

The cut moldings were then cured in water for 3 days and air dried for 24 hours.

The cured and air dried moldings in water were crushed to prepare a porous pellet type water treatment agent having a pH of 11 and a size of 10 mm.

The porous pellet was treated for 15 days to maintain the pH of the water treatment agent.

Examples 1-2

A porous pellet water treatment agent prepared in the same manner as in Example 1-1 was prepared, but a porous pellet water treatment agent exposed to the air for 15 days without sealing was prepared.

≪ Comparative Example 1 &

Comparative Example 1-1

A porous pellet-type water treatment agent was prepared in the same manner as in Example 1-1, except that MgCl ₂ and CaCl ₂ were prepared using red mud pretreated by partially neutralizing the pH of the red mud to 10.

Comparative Example 1-2

A porous pellet-type water treatment agent was prepared in the same manner as in Example 1-1, except that MgCl ₂ and CaCl ₂ were used to pre-neutralize the red mud by partially neutralizing the pH of the red mud.

[Train Removal Experiment on Freshwater]

In the porous pellet-type water treatment agent prepared in Example, in order to perform total phosphorus removal experiment in fresh water, first, 1.4325 g of potassium dihydrogen phosphate (KH ₂ PO ₄ ) was dissolved in distilled water to make the solution exactly 1000 ml, and the concentration was 1,000. A ppm phosphate (PO ₄ ^-3 ) standard solution was prepared.

After taking a certain amount from the standard solution was diluted with distilled water to make a blank (Blank) and to prepare a artificial sewage sample solution of pH 7 and concentration of 10mg / L in a 1L beaker.

0.5 g, 1 g, 1.5 g, and 2 g of the porous pellet-type water treatment agents prepared in Examples and Comparative Examples were added to each artificial sewage sample solution, and the mixture was stirred at 150 rpm for 30 minutes. It was left for 2 hours. Thereafter, each sample solution was filtered through a glass fiber filter, and then the total phosphorus (TP) was measured, and the results are shown in Table 1.

Artificial sewage sample Total Phosphorus Removal Efficiency (%) Sealed Pellet input Pellet pH Concentration (mg / L) Example 1-1 0g - 10 - 0.5 g 11 0.41 95.9 Sealing 1 g 11 0.15 98.5 Sealing 1.5 g 11 0.01 99.9 Sealing 2g 11 0.01 99.9 Sealing Examples 1-2 0g - 10 - 0.5 g 8.4 1.41 85.9 No sealing 1 g 8.4 1.15 88.5 No sealing 1.5 g 8.4 0.41 95.9 No sealing 2g 8.4 0.11 95.8 No sealing Comparative Example 1-1 0g - 10 - 0.5 g 10.5 1.14 88.6 Sealing 1 g 10.5 0.69 93.1 Sealing 1.5 g 10.5 0.28 97.2 Sealing 2g 10.5 0.12 98.8 Sealing Comparative Example 1-2 0g - 10 - 0.5 g 8.6 1.51 84.9 No sealing 1 g 8.6 1.06 89.4 No sealing 1.5 g 8.6 0.49 95.1 No sealing 2g 8.6 0.19 98.1 No sealing

As shown in Table 1, the porous pellet-type water treatment agent subjected to the sealing step as in Example 1-1, Example 1-2, and Comparative Example 1-1, Comparative Example 1-2 was the same as compared with that without the sealing step. It was confirmed that the total phosphorus removal efficiency compared to the input amount.

In addition, even when the porous pellet water treatment agent made by using the red mud made by drying without neutralization treatment shown in Example 1-1 compared to the porous pellet water treatment agent prepared by partial neutralization compared to Comparative Example 1-1, the total removal efficiency compared to the same dosage This showed rather good results. Therefore, high total removal efficiency of porous pellet water treatment agent made by drying dried red mud without neutralization treatment, simplification of production process, and presence of sealing step to maintain high pH of porous pellet water treatment agent before application to the site during manufacturing process Was found to have a significant effect on the total removal efficiency.

As shown in Table 1 above, the removal efficiency of total phosphorus (TP) was increased to 99.98% when the porous pellet water treatment agent 1.5g prepared by using the red mud was dried, and the discharged water quality standard (0.2 mg / L) was strengthened. Total phosphorus was removed to much lower levels of 0.01 mg / L. Adsorption mechanism to remove total phosphorus is FePO4, AlPO4, Ca3 (Fe, Al, Ca, and Mg contained by red mud and additives constituting porous pellet-type water treatment agent through ion stirring reaction, surface adsorption and coordination bond). The removal of total phosphorus in the form of PO4) 2 and Mg ₃ (PO ₄ ) ₂ shows that porous pellet water treatment agent using red mud made by drying only without neutralizing red mud can effectively remove total phosphorus.

[Total phosphorus and metal removal experiment on seawater]

For the porous pellet-type water treatment agent prepared in Example 1-1, total phosphorus removal and metal removal efficiency experiment in seawater was performed as follows.

In the laboratory, artificially fill a 1 L beaker with 500 ml of distilled water, adjust the initial phosphorus concentration to 10 mg / L, adjust the salt concentration to 33% (specific gravity 1.024 to 1.025), pH to 8.2 to 8.3, and alkalinity to 1carbonate. The experiment was carried out by setting to 12.2 dKH (4.2 to 4.3 meq / L), and the results are shown in Table 2.

In the laboratory, 500 ml of distilled water was artificially filled into a 1 L beaker, and the initial concentrations of copper, cadmium, and lead were adjusted to 20 mg / L, and the salt concentration was adjusted to 33% (specific gravity 1.024 to 1.025) and pH to 8.2 to 8.3 , Alkalinity was performed by setting the carbonate hardness to 11.8 ~ 12.2dKH (4.2 ~ 4.3 meq / L), the heavy metal removal results are shown in Table 3.

Input (g) P concentration (mg / L) Removal rate (%) 0 10 0 0.5 3.75 60 1.0 3.50 65 1.5 1.50 88 2.0 0.50 92 2.5 0.01 99 3.0 0.01 100

Input (g) Copper (Cu, mg / L) Lead (Pb, mg / L) Cadmium (Cd, mg / L) 0 20 20 20 One 0.2 6 13 2 0.01 3 10 3 Not detected Not detected 5 4 Not detected Not detected 2 5 Not detected Not detected 0.1 6 Not detected Not detected Not detected

As shown in Table 2 and Table 3, the porous pellet type water treatment agent of Example 1-1 was composed of a large amount of iron (Fe), calcium (Ca), aluminum (Al), and magnesium (Mg) to be dissolved in water. It can be seen that heavy metals such as copper, lead, and cadmium can be effectively precipitated and removed by hydroxides.

Accordingly, it can be seen that the porous pellet-type water treatment agent of the present invention has a high total phosphorus and heavy metal removal efficiency even in seawater containing a high concentration of salt, and is applicable to remove total phosphorus and heavy metals not only in fresh water but also in seawater and non-point pollutants.

Claims (7)

(S1) drying and pretreating the red mud by baking at a temperature of 100 to 900 ° C .;
(S2) a first mixing step of mixing portland cement (Ordinary Portland Cement, OPC) and aluminum flakes in the red mud pretreated in the step S1;
(S3) a second mixing step of mixing water with the mixture mixed in the step (S2);
(S4) molding the mixture obtained in the step (S3);
(S5) curing the molding in which the pores obtained in the step (S4) are formed in water;
(S6) drying the molding cured in the water in the step (S5); And
(S7) comprising the step of crushing the molded product dried in the step (S6) in the form of pellets, a method for producing a porous pellet-type water treatment agent.
The method of claim 1,
Red mud in the step (S1) is a pH 10 or more, the particle size of 6 ~ 10㎛ characterized in that the method for producing a porous pellet type water treatment agent.
The method of claim 1,
Drying of the step (S1) is a method for producing a porous pellet-type water treatment agent, characterized in that carried out by firing at 100 ~ 900 ℃.
The method of claim 1,
The step (S2) is a method for producing a porous pellet type water treatment agent, characterized in that 40 to 60 parts by weight of Portland cement and 0.1 to 0.3 parts by weight of aluminum flakes are mixed with respect to 100 parts by weight of the red mud pretreated in the step (S1).
The method of claim 1,
In the step (S3), the mixed water obtained by dissolving 5 to 20 parts by weight of MgCl ₂ , 3 to 6 parts by weight of CaCl ₂ and 0.2 to 0.4 parts by weight of FeSO _{4 is} dissolved in 100 parts by weight of the mixture mixed in the step (S2). Method for producing a porous pellet type water treatment agent, characterized in that mixing.
The method of claim 1,
(S8) step, the method of manufacturing a porous pellet-type water treatment agent further comprises the step of sealing to maintain the pH of the porous pellet-type water treatment agent formed in the step (S7).
The method of claim 1,
PH of the porous pellet-type water treatment agent is a method for producing a porous pellet-type water treatment agent, characterized in that 9 to 12.

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