KR20210051163A - Method of mineralcarbonation using waste asbestos slate - Google Patents

Abstract

The present invention provides a method for carbonate mineralization using detoxified waste asbestos slate comprising the following steps: manufactured a slurry of waste asbestos slate by mixing dry waste asbestos slate powder with water; obtaining a calcium eluate by adding hydrochloric acid to the waste asbestos slate slurry; performing a mineral carbonation reaction by adding carbon dioxide to the calcium eluate; and recovering the calcium carbonate produced by the mineral carbonation reaction. According to the present invention as described above, provided is the method for carbonate mineralization using detoxified waste asbestos slate, which can produce useful minerals with high efficiency and inexpensively while promoting environmental protection and public health.

Description

Carbonate mineralization method using waste asbestos slate{METHOD OF MINERALCARBONATION USING WASTE ASBESTOS SLATE}

The present invention relates to a carbonate mineralization method using harmless asbestos slate, and more particularly, by establishing an optimal carbonate mineralization condition capable of efficiently fixing carbon dioxide using harmless asbestos slate, environmental protection and The present invention relates to a carbonate mineralization method using harmless asbestos slate that can improve public health and produce useful minerals at high efficiency and inexpensively.

Asbestos is a hydrated silicate mineral that is commercially used because it is calculated in the form of fibers or needles. The Occupational Safety and Health Administration (Occupational Safety and Health Administration) uses asbestos only when it has an aspect ratio of 3:1 or more and a length of 5 µm or more. Classify.

Asbestos can be largely divided into serpentine group asbestos, chrysotile and amphibole group, asbestos, amosite, crocidolite, anthophyllite, tremolite, and actinolite.

Such asbestos has been used in more than 3,000 types of products such as textiles, construction materials, insulation materials, fireproof materials, and brake linings since the industrial revolution at the end of the 19th century due to its strong tensile strength, high temperature and low temperature environment, does not conduct electricity, and is chemically resistant to corrosion.

However, when products and wastes containing asbestos are weathered and introduced into the human body, they cause cell damage or deformation, and are not well discharged outside the body, causing diseases such as lung cancer, asbestos lung, malignant mesothelioma and pleural thickening. In fact, pulmonary disease incidence of workers in the industry that produces asbestos products or those exposed to the product has been reported steadily, and asbestos-induced pulmonary disease epidemiological investigations have demonstrated the association between asbestos inhalation and specific lung diseases.

One of the representative wastes containing such asbestos is asbestos slate. Asbestos slate is composed of 10-20% serpentine asbestos and 80-90% cement. Over time, calcium hydroxide, which is the main component of cement, dissolves in water, but other asbestos is released into the surrounding environment. It is threatening health. According to a recent survey by the Ministry of Environment, about 1.23 million asbestos slate buildings are distributed nationwide, and they have been used steadily until the 1990s, and recently, as asbestos was designated as a first-class carcinogen, and its use decreased after 2000. In addition, most of the nation's asbestos slate buildings (55.4%) were concerned about scattering of asbestos after the endurance period (30 years) has passed, and in fact, 22% of asbestos was detected in the soil collected around buildings before the 1970s.

Currently, in Korea, such asbestos slates are collected by waste companies and sealed in polyethylene containers to prevent scattering and covered in designated waste landfills. However, the reclamation capacity of waste asbestos is expected to reach saturation after 2016 (2017, 152,000 tons x 5 years). In addition, even if it is buried in a designated landfill, it is a problem because there is a possibility of being exposed to the surrounding environment again due to weathering in the future.

The present invention was conceived to solve the problems of the prior art as described above, and its object is to establish optimal carbonate mineralization conditions that can efficiently fix carbon dioxide using harmless asbestos slate, The objective is to provide a carbonate mineralization method using harmless asbestos slate that can produce useful minerals at low cost with high efficiency while promoting protection and public health.

The technical problem of the present invention as described above is achieved by the following means.

(1) preparing a waste asbestos slate slurry by mixing water with dry waste asbestos slate powder; Adding hydrochloric acid to the waste asbestos slate slurry to obtain a calcium eluate; Performing a mineral carbonation reaction by adding carbon dioxide to the calcium eluate; And recovering calcium carbonate generated by the mineral carbonation reaction.

(2) In the above (1),

The waste asbestos slate slurry comprises the step of adjusting the concentration of the waste asbestos slate slurry to be 8-10 g/L (1%) by mixing water with the detoxified dry waste asbestos slate powder. Carbonate mineralization method using.

(3) In the above (1),

Carbonate mineralization method using a detoxified waste asbestos slate comprising the step of obtaining a calcium eluate by adjusting the pH to a neutral region using hydrochloric acid and reacting for 30 to 60 minutes.

(4) In the above (1),

The waste asbestos slate slurry is adjusted so that the concentration of the waste asbestos slate slurry is 10g/L (1%) by mixing water with the detoxified dry waste asbestos slate powder, adjusted to pH 7 with hydrochloric acid, and reacted for 30 minutes. Carbonate mineralization method using detoxified waste asbestos slate, characterized in that it comprises the step of obtaining an eluate.

(5) In the above (1),

After obtaining the primary calcium eluate with hydrochloric acid, a complex organic acid composed of 1:1:1~2:2:2 of phosphoric acid, tartaric acid, and propionic acid in a weight ratio (w/w) is added together with hydrochloric acid, but the weight of hydrochloric acid Carbonate mineralization method using a detoxified waste asbestos slate, characterized in that it comprises the step of adjusting the pH to 7 by adding 10 to 30% by weight compared.

(6) In the above (1),

After heating the waste asbestos slate slurry at 100° C. for 10 to 20 minutes, water is added thereto and heated at 100° C. for 20 to 30 minutes to facilitate the elution of calcium in a subsequent process. Carbonate mineralization method using a detoxified waste asbestos slate, characterized in that.

According to the present invention as described above, by establishing the optimal carbonate mineralization conditions that can efficiently fix carbon dioxide using harmless asbestos slate, environmental protection and public health are promoted, and useful minerals are highly efficient and inexpensive. It provides a carbonate mineralization method using a detoxified waste asbestos slate that can be prepared in a way.

1 is a block diagram of a carbonate mineralization apparatus using waste asbestos slate according to the present invention.
Figure 2 is a waste asbestos slate (WAS) XRF analysis diagram.
Figure 3 is a detoxified waste asbestos slate (HWAS) XRF analysis diagram.
Figure 4 is a waste asbestos slate (WAS) SEM-EDS analysis diagram.
Figure 5 is a detoxified waste asbestos slate (HWAS) SEM-EDS analysis diagram.
^{6 is Ca 2+} elution concentration by pH of WAS, HWAS, and WC
Figure 7 is the concentration of ^{Mg 2+} elution by pH of WAS, HWAS, and WC

The carbonate mineralization method using the detoxified waste asbestos slate according to the present invention comprises the steps of preparing a waste asbestos slate slurry by mixing water with dry waste asbestos slate powder; Adding hydrochloric acid to the waste asbestos slate slurry to obtain a calcium eluate; Performing a mineral carbonation reaction by adding carbon dioxide to the calcium eluate; And recovering calcium carbonate generated by the mineral carbonation reaction.

1 is a carbonate mineralization apparatus using detoxified waste asbestos slate according to the present invention, including a waste asbestos slate slurry supply unit 10, a pH adjustment tank 20, a calcium carbonate precipitation tank 30, and a carbon dioxide supply unit 40 do.

The waste asbestos slate slurry supply unit 10 dry and pulverizes the detoxified waste asbestos slate, mixes it with water, and supplies it to the reaction in a slurry state. Preferably, the waste asbestos slate slurry is mixed with water to the detoxified dry waste asbestos slate powder [e.g., 8-10 g of dry waste asbestos slate and 1L of distilled water are mixed] so that the concentration of the waste asbestos slate is 8-10 g/L (1 %), but preferably 10g/L.

In the present invention, the detoxified waste asbestos slate may be obtained by recovering the waste asbestos slate, pulverizing it to 1 mm or less, mixing the obtained pulverized material with an inorganic material (eg, SiC) and heating it to about 1,100°C with microwaves.

Preferably, the detoxified waste asbestos slate slurry obtained as described above is heated at 100°C for 10 to 20 minutes, and then 1 to 3 times the amount of water is secondly added and heated at 100°C for 20 to 30 minutes. Pretreatment to facilitate the elution of calcium, and finally, the concentration of the slurry is adjusted to be 8-10 g/L (1%), preferably 10 g/L. In this case, it provides an effect of softening the tissue so that the subsequent elution of calcium by the acid can occur more easily.

In the pH adjustment tank 20, hydrochloric acid is added to the inputted waste asbestos slate slurry, and the pH is preferably adjusted to a neutral range of pH 2-7, more preferably pH 7. Although the pH is low, for example, it shows the highest calcium ion concentration at pH 4, when the calcium eluate is applied to the subsequent mineral carbonation process, the economical and environmental impact of the pH of the process waste or the amount of acid input are considered. As a result, it is judged that the elution condition of about pH 7 can secure sufficient calcium necessary for the mineral carbonation reaction, while also lowering the burden on the environmental impact and increasing the efficiency.

More preferably, after adding hydrochloric acid to the slurry to obtain a primary calcium eluate, a complex organic acid consisting of phosphoric acid, tartaric acid, and propionic acid in a weight ratio (w/w) of 1:1:1 to 2:2:2 is added to hydrochloric acid. However, the addition of 10 to 30% by weight relative to the weight of hydrochloric acid to adjust the pH to 7 shows high efficiency in the elution of calcium.

The mineral carbonation reactor 30 is a reaction tank in which a mineral carbonation process takes place, and reacts with carbon dioxide flowing from the carbon dioxide supply unit 40 and a pH-adjusted slurry flowing from the pH adjusting tank 20 to precipitate calcium carbonate.

When carbon dioxide flows into the gas inlet at the top of the mineral carbonation reactor 30, it is induced to diffuse as small bubbles by the pores of the perforated plate (not shown) at the bottom of the gas inlet pipe, and the acid-treated solution so that calcium is eluted from the waste asbestos slate slurry. After the reaction through the supernatant, the carbon dioxide gas discharged to the water surface exits through the gas outlet _{and moves to the CO 2} sensor 50 so that the concentration of the discharged carbon dioxide is measured in real time.

The carbon dioxide supply unit 40 can use the exhaust gas of the power generation facility, and the supply type is not required as a special limitation, and the _{exhaust gas with an average CO 2} emission concentration of about 5% is directly supplied or collected in the form of compressed gas in the tank. It can also be supplied while charged with.

Calcium carbonate formed by the reaction is precipitated at the bottom of the mineral carbonation reactor 30, and the precipitated calcium carbonate is recovered separately.

Hereinafter, the present invention will be described in more detail with the following examples. However, this is to help easier understanding of the present invention, but is not intended to limit the present invention through these.

[Example 1] Metal ion elution experiment

Experimental materials and process

Experimental materials are Waste Asbestos Slate (hereinafter'WAS' (diameter less than 1mm), Harmless Waste Asbestos (hereinafter referred to as'HWAS') (diameter less than 1mm, advanced technology) (Provided by the researcher) Waste concrete was also used as a comparative material (hereinafter referred to as'WC').

XRF(Fluoresecence X-ray Element Analyzer, SEA2220A and mobile:SEA 200, Sll Nano Technology Inc), SEM-EDS(NORMAL SEM-EDS, JSM-5400, INCAx-sight, Jeol/Oxford) of the joint laboratory of Kongju National University, Analysis was performed using ICP-OES/AES (Ioductively coupled plasma optical emission sepctrometer, OPTIMA200 DV, Perkinelmer), and the raw materials Ca ²⁺ and Mg ²⁺ were analyzed. Dissolution was conducted for WAS, HWAS, and WC using H ₂ SO ₄ and HCl.

Experiment Result 1: XRF analysis

^{It was confirmed how much Ca 2+} and Mg ^{2+, which} are materials necessary for mineral carbonation, are contained in waste asbestos slate and innoxious waste asbestos slate. As a result of measuring through XRF, the content of CaO was WAS (40.8wt%) and HWAS (37.9wt%), and the carbonation-capable material was analyzed with MgO content of WAS (10.6wt%) and HWAS (10.8wt%).

XRF analysis results of waste asbestos slate (WAS) and harmless waste asbestos slate (HWAS) XRF Result(wt%) WAS HWAS WC[9] MgO 10.6 10.8 2.7 Al ₂ O ₃ 7.4 8.2 8.7 SiO ₂ 23.1 25.9 35.8 K ₂ O 2.8 2.4 4.9 CaO 40.8 37.9 22.1 Fe ₂ O ₃ 15.3 14.8 18.5

Experimental result 2: SEM-EDS analysis

As a result of analyzing by averaging 8 spectrums of waste asbestos slate, Ca was 25.3 wt%, and as a result of analyzing 12 spectrums of harmless waste asbestos slate, Ca was 37.7 wt%, and Mg was 10.2 wt% of WAS. , HWAS was analyzed at 6.2wt%. WC (Waste Concrete) was analyzed as 16.2wt% and 5.4wt% of Ca and Mg, which show lower values than the harmless waste asbestos slate.

SEM-EDS analysis results of waste asbestos slate and harmless waste asbestos slate (wt%) SEM-EDS result Average WAS
norm.C HWAS
norm.C WC[9]
norm.C C 21.6 5.9 7.1 O 30.2 34.3 38.7 Na - 0.9 0.6 Mg 10.2 6.2 5.4 Al 1.2 2.3 8.6 Si 9.7 8.7 14.2 K 0.5 0.8 3.1 S 0.6 0.9 0.8 Ca 25.3 37.7 16.2 Fe 1.1 1.4 5.5 Cu - 0.61 0.3 SUM 100.41 99.17 100.5

Experimental result 3: ICP-OES/AES analysis

Water was mixed with the waste asbestos slate sample and the detoxified waste asbestos sample and adjusted to 1g/100mL to make a slurry. The elution solvent was _{applied to the slurry using H 2} SO ₄ and HCl, respectively, and the pH was 11, 9, 7, 5, and 3, while Ca ²⁺ , Mg ²⁺ , and Si ⁺ were eluted for 5 minutes. Analyzed by ICP-OES / AES in HCl, pH 3 waste asbestos slate Ca ²⁺ is Ca ²⁺ in 2,761.71mg / L, the detoxified asbestos waste It was analyzed as high as 2,65.36mg/L. Mg ²⁺ is in the same manner as Ca ²⁺ HCl, in a waste asbestos slate at pH 3 is Mg ²⁺ waste asbestos slate or a detoxifying've found to 93.88mg / L concentration showed a higher concentration to 213.87mg / L.

Comparison ^{of ICP-OES/AES Ca 2+} concentration of waste asbestos slate, detoxified waste asbestos slate, and waste concrete pH WAS(mg/L) HWAS(mg/L) WC(mg/L) H ₂ SO ₄ HCl H ₂ SO ₄ HCl HCl 11 103.02 54.76 96.89 128.68 30.98 9 693.48 678.08 1,287.51 1,644.15 151.78 7 965.53 2,089.63 1,547.29 2,132.80 563.23 5 1,826.80 1,893.90 994.01 2,592.40 826.45 3 2,187.43 2,761.71 1,043.60 2,653.36 984.17

Comparison ^{of ICP-OES/AES Mg 2+} concentration of waste asbestos slate, detoxified waste asbestos slate, and waste concrete pH WAS(mg/L) HWAS(mg/L) WC(mg/L) H ₂ SO ₄ HCl H ₂ SO ₄ HCl HCl 11 0.42 0.48 0.09 0.09 0.17 9 10.19 6.32 41.17 90.24 1.36 7 17.80 43.10 123.87 133.63 7.99 5 33.21 34.17 165.19 190.93 18.82 3 81.05 93.88 201.46 213.87 34.75

As described above, as a result of analyzing waste asbestos slate (WAS), detoxified waste asbestos slate (HWAS), and waste concrete (WC) in various ways, it _{is eluted with H 2} SO ₄ and HCl, and the pH is adjusted while stirring at 1 g/100 ml. I did. As a result of the elution, the lower the pH, the ^{higher the concentration of Ca 2+ and Mg 2+} was, and the elution concentration of mineral carbonation-related ions was higher in HWAS than in WAS. In the detoxification process, it is believed that it was transformed into a more advantageous raw material for mineral carbonation due to the destruction and transformation of the crystalline structure through high-temperature microwaves. When eluted with HCl at pH 5, Ca ²⁺ of WAS is 189.3 mg(Ca ²⁺ )/1g (WAS), Ca ²⁺ of HWAS is 259.2 mg(Ca ²⁺ )/1g(HWAS), which is different from pH 3 Contrasting results came out, which shows that the decomposition of the crystallized structure due to detoxification is advantageous in that raw materials capable of mineral carbonation are eluted even if the pH is not lowered. In addition, waste concrete has only about half the elution of waste asbestos slate and detoxified waste asbestos slate, so waste asbestos slate and detoxified waste asbestos slate are considered more advantageous raw materials for mineral carbonation.

[Example 2] Elution of ^{Ca 2+} ions in waste asbestos slate according to pH using complex organic acid

After the first treatment with hydrochloric acid, phosphoric acid, secondly, tartaric acid, and propionic acid in a weight ratio (w/w) of 1:1:1 were added together with hydrochloric acid, but 10% by weight of hydrochloric acid was added. ^{When the Ca 2+} ion elution experiment was performed by the same procedure as in Example 1 above except that the pH was adjusted to 7, HWAS was 2,315 mg/L at pH 7.

[Example 3] Effect of ^{reaction time on Ca 2+ ion elution}

As a result of eluting calcium ions in the detoxified waste asbestos slate (1 g/L) according to the reaction time at pH 5 using hydrochloric acid (HCl), the average reaction time was 2,653.36 mg/L at 5 minutes, and the average at 10 minutes. 3,242.5mg/L, an average of 4,235.5mg/L at a reaction time of 15 minutes, an average of 6,265.0mg/L at a reaction time of 20 minutes, an average of 7,385.5mg/L at a reaction time of 25 minutes, an average of 8,107.0mg/L at a reaction time of 30 minutes, reaction An average of 8,185.5mg/L at 35 minutes, an average of 8,329.0mg/L at a reaction time of 40 minutes, an average of 8,280.0mg/L at a reaction time of 45 minutes, an average of 8,149.0mg/L at a reaction time of 50 minutes, and an average of 8,340.0 at a reaction time of 55 minutes It was expressed as an average of 8,295.0 mg/L at mg/L and a reaction time of 60 minutes. Up to 30 minutes of reaction time, the concentration of eluted calcium showed a tendency to increase continuously, but at more than 30 minutes, the concentration increase was slower than the optimum reaction time. Therefore, it is judged that a reaction time of 30 minutes is suitable in the calcium ion elution step.

[Example 4]

After heating the detoxified waste asbestos slate slurry (1 g/L) used in Example 1 at 100°C for 20 minutes, water was added thereto and heated at 100°C for 30 minutes to obtain the concentration of the waste asbestos slate slurry. When the same experiment as in Example 1 is repeated using the adjusted to 1 g/L again (pH 7), the elution concentration of calcium ions at 5 minutes is high, on average, 2,678.2 mg/L.

[Example 5]

In order to evaluate the mineral carbonation reaction efficiency, a batch reaction process as shown in FIG. 1 was devised. The carbon dioxide gas used in the experiment was _{mixed with Air and 99.99% CO 2} with a MFC (Mass Flow Controller) to prepare 5% CO _{2 so that the average CO 2} emission concentration of the power plant exhaust gas was 5%.

_{5% CO 2} gas mixed and prepared by MFC was introduced into the mineral carbonation reactor as shown in FIG. 1 to fill the inside of the reactor (a sample obtained under pH 7 using the detoxified waste asbestos slate of Example 1) and After the reaction, it is discharged to the gas outlet at the top of the mineral carbonation reactor. The exhausted carbon dioxide gas was _{introduced into the CO 2} sensor so that the concentration of the exhaust gas could be measured. In the mineral carbonation reactor of FIG. 1, when carbon dioxide flows into the gas inlet at the top, it is induced to diffuse as small bubbles by the pores of the perforated plate at the bottom of the gas inlet pipe, and the reaction passes through the supernatant of the acid-treated solution so that calcium is eluted from the waste asbestos slate. Afterwards, the carbon dioxide gas discharged to the water surface exits through the gas outlet _{and moves to the CO 2} sensor to measure the concentration of the discharged carbon dioxide in real time.

_{In addition, CO 2} concentration and calcium ion concentration were measured in real time to confirm the reaction trend during the mineral carbonation reaction in the mineral carbonation reactor. As a result, as shown in Table 5, it was observed by the naked eye that the concentration of carbon dioxide discharged and the concentration of calcium ions in the sedimentation tank decreased, and the precipitation at the bottom gradually increased. As a result, it was found that the mineral carbonation reaction proceeded smoothly.

Reaction time CO ₂ Ca ²⁺ (mg/L) 10 minutes 3.2% 1,518.7 20 minutes 2.3% 682.8 30 minutes 0.2% 325.3

As described above, although it has been described with reference to a preferred embodiment of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

10: Waste asbestos slate slurry supply unit
20: pH adjustment tank
30: calcium carbonate precipitation tank
40: carbon dioxide supply

Claims (6)

Preparing waste asbestos slate slurry by mixing water with waste asbestos slate powder; Adding hydrochloric acid to the waste asbestos slate slurry to obtain a calcium eluate; Performing a mineral carbonation reaction by adding carbon dioxide to the calcium eluate; And recovering calcium carbonate generated by the mineral carbonation reaction. The method of claim 1,
The waste asbestos slate slurry comprises the step of adjusting the concentration of the waste asbestos slate slurry to be 8-10 g/L (1%) by mixing water with the detoxified dry waste asbestos slate powder. Carbonate mineralization method using. The method of claim 1,
Carbonate mineralization method using detoxified waste asbestos slate, comprising the step of obtaining a calcium eluate by adjusting the pH to a neutral region using hydrochloric acid and reacting for 30 to 60 minutes. The method of claim 1,
The waste asbestos slate slurry is adjusted so that the concentration of the waste asbestos slate slurry is 10g/L (1%) by mixing water with the detoxified dry waste asbestos slate powder, adjusted to pH 7 with hydrochloric acid, and reacted for 30 minutes. Carbonate mineralization method using detoxified waste asbestos slate, characterized in that it comprises the step of obtaining an eluate. The method of claim 1,
After obtaining the primary calcium eluate with hydrochloric acid, a complex organic acid composed of 1:1:1~2:2:2 of phosphoric acid, tartaric acid, and propionic acid in a weight ratio (w/w) is added together with hydrochloric acid, but the weight of hydrochloric acid Carbonate mineralization method using a detoxified waste asbestos slate comprising the step of adjusting the pH to 7 by adding 10 to 30% by weight of the ratio. The method of claim 1,
After heating the waste asbestos slate slurry at 100° C. for 10 to 20 minutes, water is added thereto and heated at 100° C. for 20 to 30 minutes to facilitate the elution of calcium in a subsequent process. Carbonate mineralization method using a detoxified waste asbestos slate, characterized in that.

Images