KR101268633B1 - Treating Agent For Acidic Waste Liquid Treatment, and Treatment Process Using The Same - Google Patents

Abstract

The present invention comprises the steps of cooling the blast furnace slag containing S as a by-product of the steelmaking process to prepare a water slag; Crushing the wood slag to a size of 100 μm or less; And a hydrothermal reaction of the crushed reclaimed slag and the acidic waste solution containing the heavy metal in a reactor. The present invention relates to an acidic waste solution treating method including an acidic waste solution containing a heavy metal.

Description

Treatment agent for acidic waste liquid and method for treating acid waste liquid using same {Treating Agent For Acidic Waste Liquid Treatment, and Treatment Process Using The Same}

The present invention relates to a treatment agent for treating acidic waste liquid and a method for treating acidic waste liquid using the same, and more particularly, a treatment agent for treating acidic waste liquid which can fix toxic heavy metal components in a stable hydrothermal phase without generating a large amount of sediment and the same. It relates to a method of treating acidic waste used.

The present invention relates to a method for treating acidic waste liquid containing heavy metals harmful to human body by hydrothermal reaction using slag generated in steelmaking process. The following describes the generation process of the acidic waste liquid containing heavy metals and the treatment method of the acidic waste liquid.

Waste liquids containing heavy metals are discharged from various aspects of the metal smelting industry, and they are made in various forms depending on the type of metal, process and plant size. Typical examples thereof include acidic wastewater including pickling waste liquid and plating waste liquid.

The pickling liquor is strongly acidic, and is an operation that cleans the surface by dissolving / removing the scale attached to the metal surface by immersing the metal in sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid, or a mixture of these acids while heating after the annealing process of the metal. It means that it is generated by a pickling process. In addition, the pickling liquid attached to the metal surface taken out of the pickling liquid is washed with fresh water, and the wastewater generated at this time is called a pickling wastewater. As described above, the pickling process generates a high pickling waste liquid and a relatively low concentration of pickling waste water in which the pickling liquid is diluted with fresh water.

The plating waste liquid is generated in the plating process similar to the above, and generates two kinds of waste liquids including a plating liquid and washing water. Metal products processed to the desired shape are plated after removing dirt and rust from the surface. In the plating process, the substrate to be plated acts as a cathode and the metal in the solution to be coated on the substrate acts as a cathode. The amount of wastewater discharged from the plating plant is relatively small, but it is a dangerous wastewater because it contains not only metals such as chromium and copper, but also toxic substances such as tetrachloride.

Today, most of the acidic wastewater generated in Korea is treated by simple neutralization method using limestone or quicklime. However, when the acidic wastewater is discharged, the water quality standards are being strengthened, and the treated acidic wastewater contains nitrogen oxides (NO _X ). It has a problem such as being included and discharged. In addition, technologies for recovering metal elements and acids from acidic wastewater are attracting attention, but are still in the research stage. The composite metal hydroxide sludge produced by the neutralization method must be dehydrated at least 90%, and the dehydration of at least a predetermined amount must be dependent on natural evaporation, which makes it difficult to handle. In particular, in the case of chromium present as hexavalent chromium in wastewater, unlike copper, iron, nickel, zinc, etc., which easily generate hydroxides under alkaline conditions, they are not precipitated under alkaline conditions and are more toxic than trivalent chromium. That is, the hexavalent chromium is troublesome to separately carry out the process of reducing the trivalent chromium before it is precipitated with chromium hydroxide. Barium, lead, silver and the like are known to react with chromium ions to form an insoluble precipitate, but the barium, lead, silver and the like are not only expensive but also likely to cause secondary pollution, which is not suitable for wastewater treatment.

In addition to the acidic waste liquids described above, heavy metals contained in the acid mine drainage (AMD) generated from the abandoned mines are also causing serious environmental pollution. At present, it is known that about 1,000 mines are abandoned in Korea, and some of them are not properly managed after the mine. In addition, waste-rock and mine wastes (tailings) are left unattended around many waste mines, and contaminants such as various types of harmful heavy metals in the leachate of mine wastes continue to cause water-soil-air pollution. Leachate does not have a constant flow rate and occurs intermittently, but contains highly toxic substances such as arsenic, lead, and cadmium. Once discharged downstream, the leachate gradually pollutes the water system and soil, which makes it difficult to recover. Previously, the mine water treatment has been mainly studied, and the treatment methods used are lime softening, ion exchange, activated alumina, biological sulfate reduction, iron-manganese oxidation (Fe-Mn Oxidation), aeration and dissolved oxygen flotation.

An object of the present invention devised to solve the above problems is to provide a method for treating an acidic waste liquid including heavy metals.

In addition, another object of the present invention is to provide a method for treating an acidic waste liquid without generating an hydroxide or the like and without an environmental load.

In addition, another object of the present invention is to provide a treatment agent for acidic waste liquid using a by-product of the iron making process.

According to a feature of the present invention for achieving the object as described above, the present invention comprises the steps of cooling the blast furnace slag containing S as a by-product of the steelmaking process to prepare as a water slag; Crushing the wood slag to a size of 100 μm or less; And hydrothermally reacting the crushed reclaimed slag with an acidic waste solution containing heavy metals in a reactor.

The preparing of the reclaimed slag may be performed by melting the blast furnace slag at 1600 ° C. for 10 minutes and then cooling the water.

S may be 0.5% to 2.0% by weight.

The acidic waste liquid may be hydrothermally reacted at 10 ml per 1 g of the reclaimed slag.

In addition, the hydrothermal reaction may be performed for at least 24 hours at a temperature of 200 ~ 250 ℃.

The heavy metal may include at least one of Cr, As, and Cd.

The heavy metal is fixed in a stable hydrothermal phase after the hydrothermal reaction, the hydrothermal phase is tobermorite (Ca ₅ Si ₆ O ₁₆ (OH) ₂ 4H ₂ O) or uvarovite (Ca ₃ Cr ₂ (SiO ₄ ) ₃ ) may be included.

In addition, according to another feature of the present invention, the present invention is an acid waste treatment agent that hydrothermally reacts with an acid waste treatment agent containing a heavy metal, the acid waste solution treatment agent by weight, containing 0.5 ~ 2.0% of S but less than 100㎛ It has a size of, and hydrothermal reaction with the acidic waste liquid to produce a heavy metal hydrothermal phase, the generated hydrothermal phase relates to an acidic waste treatment agent, characterized in that fixed to the acidic waste liquid treatment agent.

The acidic waste treatment agent may include a reclaimed slag prepared by cooling the blast furnace slag.

The hydrothermal phase may be at least one of tobermorite (Ca ₅ Si ₆ O ₁₆ (OH) ₂ 4H ₂ O) or uvarovite (Ca ₃ Cr ₂ (SiO ₄ ) ₃ ). It may include.

According to the present invention as described above, it is possible to provide a method for treating an acidic waste liquid including a heavy metal.

According to the present invention, it is possible to provide a method for treating an acidic waste liquid having no environmental load without generating hydroxide precipitation.

In addition, according to the present invention can provide a treatment agent for acidic waste liquid using a by-product of the steelmaking process.

1 is a flow chart showing an acidic waste liquid treatment method according to a preferred embodiment of the present invention.
2 is a schematic diagram of an autoclave according to an embodiment of the invention.
3 is a graph showing the residual Cr concentration in the acidic waste solution according to the hydrothermal reaction time.
4 is a XRD graph after the hydrothermal reaction according to the embodiment.
5 is a graph showing the Cr concentration eluted after 12 hours and 24 hours hydrothermal reaction according to the embodiment.
Figure 6 is a graph showing the residual As concentration and Cd concentration in the acidic waste solution according to the hydrothermal reaction time.

Specific details of other embodiments are included in the detailed description and the drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various forms. In the following description, it is assumed that a part is connected to another part, But also includes a case in which other elements are electrically connected to each other in the middle thereof. In the drawings, parts not relating to the present invention are omitted for clarity of description, and like parts are denoted by the same reference numerals throughout the specification.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

1 is a flow chart showing an acidic waste liquid treatment method according to a preferred embodiment of the present invention.

Acidic waste liquid treatment method according to a preferred embodiment of the present invention comprises the steps of cooling the blast furnace slag containing S as a by-product of the iron making process to prepare as a water slag (water slag preparation step; S1); Crushing the handmade slag to a size of 100 µm or less (handling slag crushing step; S2); And hydrothermally reacting the acid waste fluid containing the crushed reclaimed slag and heavy metal in a reactor (hydrothermal reaction step; S3). The reactor may be an autoclave, and the autoclave is described below by way of example, but is not limited thereto.

The hydrothermal reaction in the hydrothermal reaction step (S3) is a chemical reaction that proceeds under conditions of high temperature / high pressure water, and it is possible to increase solubility, increase reaction rate, and shift chemical equilibrium to an impossible range under normal pressure. Various mineral phases can be created or artificially synthesized. Before and after the critical temperature of the water (374.2 ℃), it is carried out in a pressure range of several hundred to several thousand atmospheres, for example, it can be carried out using a specially designed high pressure reactor including an autoclave and the like. The hydrothermal reaction can be utilized in the production of high value-added construction materials, such as ALC, as well as gemstones, such as quartz. Artificial synthesis can be applied mainly to silica-alumina-based minerals, and steel slag, in particular blast furnace slag, can be one of the suitable materials. In the present invention, the blast furnace slag containing S as a by-product of the steelmaking process is cooled to prepare water slag, and the slag is crushed to a size of 100 μm or less, and the autoclave is crushed to a size of 100 μm or less. Acidic waste liquid can be treated by hydrothermal reaction.

The reclaimed slag preparation step (S1) includes treating the blast furnace slag with reclaimed slag for use in hydrothermal reaction. The blast furnace slag may be produced by melting the slag at 1600 ° C for 10 minutes and then cooled by water (bulk). In addition, the blast furnace slag may contain S, the S may be 0.5% to 2.0% by weight.

In making slag rolls of blast furnace slag, temperature and time may act organically related to each other. If the temperature is above 1600 ° C., the time can be shortened while the process can be difficult to control. When the time exceeds 10 minutes, the production efficiency is reduced, it may be preferable that the blast furnace slag is melted for 10 minutes at 1600 ℃.

The reclaimed slag prepared by the reclaimed slag preparation step (S1) may be crushed to a size of 100 μm or less by the reclaimed slag crushing step (S2).

In the case where the crushed reclaimed slag is more than 100 μm, the surface-to-volume ratio may be reduced to decrease the reaction efficiency. In addition, the migration of S, which is used to fix heavy metals in the hydrothermal phase, may be reduced, which may require additional additional slag to increase the amount of by-products.

Hydrothermal reaction step (S3) is a hydrothermal reaction of an acidic waste solution containing heavy metals in an autoclave with the crushed wood slag, for example, the acidic waste fluid can be hydrothermally reacted with 10ml per 1g of the wood slag have. That is, it is adjusted to 10 ml of acid waste per 1 g of the reclaimed slag and placed in the reaction vessel such as an autoclave together with the reclaimed slag.

The volume of the autoclave may depend on the amount of acidic waste to be treated, but in view of the difficulty of maintaining the pressure, the volume of the autoclave is preferably 100 ml or less. In addition, the autoclave can be produced by differentiating the inner and outer materials, the inside of the contact with the acidic solution is made of Teflon excellent in the reaction resistance, the outside to withstand high temperature and high pressure can be made of stainless steel. The opening and closing portion of the autoclave may be sufficiently sealed to maintain a saturated steam pressure of water by using an O-ring and a vacuum cream. After the autoclave is sealed, it can be reacted for a predetermined time while heating to a constant temperature. At this time, an external heating furnace for heating the autoclave is suitable for a muffle furnace that can be uniformly heated.

The hydrothermal reaction may be performed for at least 24 hours at a temperature of 200 ~ 250 ℃.

The hydrothermal reaction can be carried out before or after the critical temperature of the water (374.2 ℃), the higher the temperature can promote the reaction, while inhibiting the generation of a stable hydrothermal phase. Therefore, it is important to set the temperature of the hydrothermal reaction in consideration of both the reaction rate and the stable hydrothermal phase. If the temperature during the hydrothermal reaction is more than 250 ℃, while the hydrothermal reaction proceeds quickly, the formation of the hydrothermal phase is inhibited, the acidic waste liquid treatment may be incompletely proceeded. In addition, when the temperature during the hydrothermal reaction is less than 200 ℃, the formation of the hydrothermal phase is stable but the reaction rate is reduced can reduce the process efficiency. In addition, the hydrothermal reaction temperature is 200 ~ 250 ℃ temperature is very low compared to the general ceramic processing temperature, which represents the reaction environmental superiority of the hydrothermal reaction, and the potential of using the sensible heat generated when melting the slag slag It also implies. The time of the hydrothermal reaction may be 24 hours or more in consideration of the reduction rate of heavy metal ion concentration and the hydrothermal phase formation rate (about 0.5 μm / hour). If the time of the hydrothermal reaction is less than 24 hours, the time for generating the hydrothermal phase is not enough, there may be a large amount of unreacted heavy metal in the acid waste.

The heavy metal in the acidic waste liquid may include at least one of Cr, As, and Cd, and the heavy metal is fixed to a stable hydrothermal phase after the hydrothermal reaction, and the hydrothermal phase is tobermorite (Ca ₅ Si). ₆ O ₁₆ (OH) _2. 4H ₂ O) or uvarovite (Ca ₃ Cr ₂ (SiO ₄ ) ₃ ). By the above-described reaction, the heavy metal in the acidic waste liquid may be hydrothermally phased, and the hydrothermally phased heavy metal may be fixed to the water slag.

During the hydrothermal reaction, the metal slag such as calcium and silicon may be eluted in the aqueous solution in the reclaimed slag, and the eluted metal element may react with the hydroxide ions formed by the acidic waste solution to generate a stable hydrothermal phase tobermorite. In addition, the heavy metal in the acidic waste liquid reacts with extra calcium, silicon, and the like to create another hydrothermal reaction phase, and at the same time, it can be fixed therein by using tobermorite generated on the powder surface of the reinforcing slag. The acidic waste liquid after hydrothermal reaction is significantly reduced in heavy metal components and can be recovered and reused using other metal element recovery processes.

Below, the fixing mechanism of the heavy metal in solution is demonstrated on behalf of the case of chromium (Cr).

Chromium ions are present in the form of ubarobyte after hydrothermal reaction. Ubarobyte is a mineral having excellent high temperature stability. Can be. In addition, since the valence of chromium in trivalent ubalobite is trivalent, it can be seen that chromium ions (including complex ions) that existed at a hexavalent value in the hydrothermal reaction are also reduced to the trivalent amount. The reduction reaction of chromium ion is due to S contained in blast furnace slag or reclaimed slag and can be carried out according to the following reaction formula. S contained in the blast furnace slag or reclaimed slag can reduce the chromium from hexavalent ions to trivalent ions, and thus does not require a separate reducing agent such as ferrous sulfate and sulfurous acid gas, thereby reducing production costs. In addition, since the step of adding a reducing agent can be omitted, productivity can be increased.

Scheme:

In addition, heavy metals such as cadmium (Cd), lead (Pb), or arsenic (As), etc., do not have a wide variety of valences that may be present as compared to chromium described above, and chemical characteristics do not change significantly for each valence. That is, the reduction conditions of chromium using hydrothermal reaction may be the harshest conditions than the reduction conditions of other heavy metals, and when the chromium is reduced, other heavy metals such as cadmium, lead or arsenic are performed before the reduction of chromium. Can be.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only a preferred embodiment of the present invention, and the scope of the present invention is not limited by the following examples.

(Examples and Comparative Examples)

In order to confirm the fixed phenomenon of the heavy metals in the acidic waste liquid, an example prepared by blast furnace slag containing S as a by-product of the steelmaking process and a comparative example prepared by blast furnace slag minus S were prepared. This is shown in Table 1.

weight% CaO Al ₂ O ₃ SiO ₂ MgO S Etc Comparative example 42 15 37 6 - Example 41 15.5 35 7 1.5

In order to prepare Examples and Comparative Examples, each reagent was carefully mixed to the desired components as shown in Table 1. Thus prepared examples and comparative examples in the form of blast furnace slag was melted for a time (10 minutes) sufficient for homogeneous melting at 1600 ℃ and then quenched to prepare a hand slag. The handmade slag was crushed finely to take a size of 100 μm or less and prepared in Examples and Comparative Examples of Table 1.

Acidic waste solution was prepared by distilled water with potassium dichromate (K ₂ Cr ₂ O ₇ ) for chromium (in case of other heavy metals), and the concentration of each heavy metal (Cr ^{6 +,} etc.) in 1000 mg / L. ) Produced by adding the appropriate amount.

2 is a schematic diagram of an autoclave according to an embodiment of the present invention.

Referring to FIG. 2, the autoclave 10 is a reactor in which hydrothermal reaction of the reclaimed slag 14 and the acidic waste solution 13 proceeds. An inner container 11 made of Teflon and an outer container made of stainless steel 12 It can be composed of). The outer container 12 may include an acidic waste solution 13 and a reclaimed slag 14.

About 1 g of powdered wood slag 14 and about 10 ml of acidic waste liquid 13 were sealed in the autoclave 10 as shown in Fig. 2, and then heated to 250 ° C. Hydrothermal reaction was carried out for 18 hours. After reacting for each time, the slag was filtered and the residual heavy metal concentration in the acidic waste liquid was analyzed.

3 is a graph showing the residual Cr concentration in the acidic waste solution according to the hydrothermal reaction time. Referring to FIG. 3, in the hydrothermal reaction between an acidic waste solution containing Cr and an example and a comparative example, the Cr concentration decreases depending on the reaction time, but the reduction rate of Cr concentration is superior to that of the comparative example when using the example. Could confirm. In addition, in the case of the comparative example, after 12 hours it was confirmed that the Cr concentration in the acidic waste liquid is not reduced. That is, it can be seen that the embodiment using the blast furnace slag containing S is significantly reduced in change in Cr concentration with time compared to the comparative example using the blast furnace slag not containing S.

4 is an XRD graph after hydrothermal reaction according to an embodiment. Referring to FIG. 4, according to an embodiment of the present invention, hydrothermal images such as tobermorite and ubarobyte may be identified. In particular, it can be seen that Ubarobyte contains chromium. In addition, the ubalobite was found to be remarkable when the reaction was hydrothermal reaction temperature of more than 250 ℃ and reaction time 24 hours or more. The chromium was confirmed to exist as trivalent ions.

5 is a graph showing the Cr concentration eluted after 12 hours and 24 hours hydrothermal reaction according to the embodiment. 5 is for confirming the stability of the generated hydrothermal image. Reclaimed slag after 12 and 24 hours hydrothermal reaction, respectively, was immersed in distilled water in a Teflon vessel. The Teflon vessel was shaken using a vibrating vessel (200 rpm), and the Cr concentration in the distilled water was confirmed according to the immersion time. As shown in FIG. 5, in the case of the hot slag subjected to hydrothermal reaction for 12 hours, Cr was rapidly eluted from the hot slag. On the other hand, it was confirmed that Cr was not eluted in the case of hot slag subjected to hydrothermal reaction for 24 hours. This means that the hydrothermal phase generated through sufficient hydrothermal reaction time is chemically stable and the heavy metal (chromium) is safely fixed.

The blast furnace slag-containing embodiment containing the S, for example, may act as an acidic waste liquid treatment agent that hydrothermally reacts with an acidic waste liquid treatment agent containing heavy metals. At this time, the acidic waste liquid treatment agent containing 0.5% to 2.0% by weight of S, but having a size of 100㎛ or less, and hydrothermal reaction with the acidic waste liquid to produce a heavy metal hydrothermal phase, the generated hydrothermal phase is the acid It can be fixed to the waste treatment agent. In addition, the acidic waste treatment agent may include a reclaimed slag prepared by water cooling the blast furnace slag. The hydrothermal phase may include any one or more of tobermorite or ubarobyte.

Figure 6 is a graph showing the residual As concentration and Cd concentration in the acidic waste solution according to the hydrothermal reaction time. 6 is a result of confirming the residual As concentration and the Cd concentration in the acidic waste liquid after hydrothermal reaction of the acidic waste liquid using the Example similarly to the above. The hydrothermal reaction was carried out using an acidic waste solution containing AS or Cd (initial concentration of 1000 ppm). As concentration and Cd concentration with hydrothermal reaction time decreased gradually with hydrothermal reaction time. After the hydrothermal reaction, it was confirmed that the residual As concentration and Cd concentration in the acidic waste liquid were significantly reduced.

As described above, the acid waste liquid generated in the steelmaking process can be easily treated using the acid waste liquid treating method and the acid waste liquid treating agent according to the present invention. In addition, since the base material of the treatment agent for treating acidic waste liquid may use the blast furnace slag as a by-product of the smelting process, it is possible to improve the production efficiency without adding a separate cost. In the method of treating acidic waste liquid according to the present embodiment, it is not necessary to add a reducing agent for reducing heavy metal ions such as chromium ions, and precipitation of hydroxide or carbonate generated by the addition of the reducing agent does not occur. It can be used advantageously and economically.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalents thereof are included in the scope of the present invention Should be interpreted.

10: autoclave 11: inner container
12: outer container 13: acidic waste liquid
14: Hand slag

Claims (10)

Cooling the blast furnace slag containing S, a by-product of the steelmaking process, to prepare water slag;
Crushing the wood slag to a size of 100 μm or less; And
And hydrothermally reacting the acid waste solution containing the crushed reclaimed slag and heavy metal in a reactor. The method of claim 1,
The preparing of the reclaimed slag is characterized in that the blast furnace slag is melted at 1600 ° C. for 10 minutes and then cooled with water. The method of claim 1,
S contained in the blast furnace slag is a weight percent, acid waste treatment method characterized in that 0.5 to 2.0%. The method of claim 1,
The acidic waste solution treatment method, characterized in that the hydrothermal reaction by 10ml per 1g of the reclaimed slag. The method of claim 1,
The hydrothermal reaction is acid waste treatment method characterized in that carried out for at least 24 hours at a temperature of 200 ~ 250 ℃. The method of claim 1,
The heavy metal is acidic waste solution treatment method comprising at least one of Cr, As, Cd. The method of claim 1,
The heavy metal is fixed in a stable hydrothermal phase after the hydrothermal reaction, the hydrothermal phase is tobermorite (Ca ₅ Si ₆ O ₁₆ (OH) ₂ 4H ₂ O) or uvarovite (Ca ₃ Cr ₂ (SiO ₄ ) ₃ ) acid waste liquid treatment method comprising at least one. An acidic waste liquid treatment agent that hydrothermally reacts with an acidic waste liquid containing heavy metal, wherein the acidic waste liquid treating agent is 0.5% to 2.0% by weight, and has a size of 100 μm or less, and the acidic waste liquid treating agent is used with the acidic waste liquid. Acidic waste fluid treatment agent characterized in that the hydrothermal reaction to fix the heavy metal in the hydrothermal phase in the acid waste. 9. The method of claim 8,
The acidic waste liquid treatment agent comprises an acidic slag produced by cooling the blast furnace slag. 9. The method of claim 8,
The hydrothermal phase comprises at least one of tobermorite (Ca ₅ Si ₆ O ₁₆ (OH) ₂ 4H ₂ O) or uvarovite (Ca ₃ Cr ₂ (SiO ₄ ) ₃ ). Acidic waste liquid treatment agent characterized in that.

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