METHOD OF ASBESTOS DETOXIFICATION

Abstract

Provided is a method of asbestos detoxification including: preparing asbestos which is a treatment target for detoxification and carbon dioxide; and pressing the asbestos and the carbon dioxide with a pressure of 1 to 5 GPa and treating the asbestos and the carbon dioxide at a temperature of 100 to 250° C., wherein since the asbestos is not subjected to chemical pre-treatment, as compared to the existing technologies in which the chemical pre-treatment is necessary, treatment cost may be reduced, and another concern for environmental contamination may be prevented in advance, and accordingly, the asbestos is appropriate for recycling through detoxification as well as waste treatment.

Claims

1. A method of asbestos detoxification comprising: preparing asbestos which is a treatment target for detoxification and carbon dioxide; and treating the asbestos and the carbon dioxide under a pressure of 1 to 5 GPa and at a temperature of 100 to 250° C.

2. The method of claim 1, wherein the carbon dioxide is solidified.

3. The method of claim 1, wherein in the pressing of the carbon dioxide with 1 to 5 GPa, a pressure device is used, the pressure device being selected from the group consisting of a diamond anvil cell (DAC) device, a high-pressure cylinder device, and a high-pressure press device.

4. The method of claim 1, in treating the asbestos and the carbon dioxide under a pressure of 1 to 5 GPa and at a temperature of 100 to 250° C., pressing and heating are performed alternately that the pressure and the temperature are raised by stages up to the pressure of 1 to 5 GPa and the temperature of 100 to 250° C.

5. The method of claim 1, wherein the asbestos is not subjected to chemical pre-treatment.

6. The method of claim 1, wherein the asbestos is Tremolite or Chrysotile.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 shows a fibrous tissue of asbestos.

[0019] FIG. 2A is a microscope image of the asbestos, Tremolite, and FIG. 2B is a microscope image of the asbestos, Chrysotile.

[0020] FIG. 3A and FIG. 3B show a pressure device according to an exemplary embodiment of the present invention.

[0021] FIG. 4 is a flow chart showing a method of asbestos detoxification according to an exemplary embodiment of the present invention.

[0022] FIGS. 5A and 5B are microscope images of asbestos treated according to the method of asbestos detoxification according to an exemplary embodiment of the present invention, and specifically, FIG. 5A is a microscope image of Tremolite, and FIG. 5B is a microscope image of Chrysotile.

[0023] FIGS. 6A and 6B are microscope images of asbestos treated with high temperature/high pressure in a state in which H.sub.2O is injected rather than injecting CO.sub.2, and specifically, FIG. 6A is a microscope image of Tremolite, and FIG. 6B is a microscope image of Chrysotile.

[0024] FIG. 7 shows XRD analysis results of Tremolite treated according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF MAIN ELEMENTS

[0025] 100: Pressure device 110: Pressing means 120: Gasket 121: Through hole

DETAILED DESCRIPTION OF EMBODIMENTS

[0026] FIG. 3A and FIG. 3B show a pressure device 100 according to an exemplary embodiment of the present invention. The pressure device 100 includes a gasket 120 into which a sample, i.e., a compression target is inserted and pressing means 110 that apply pressure to the sample, i.e., the compression target.

[0027] The gasket 120 includes a through hole 121 formed at a predetermined point, preferably, in the center. Asbestos, i.e., treatment target, and solidified carbon dioxide (CO.sub.2) are inserted together into the through hole 121. The solidified carbon dioxide may be used in an amount 0.5 to 2 times that of the asbestos, preferably, about 1 time the amount as the asbestos (on the basis of volume ratio).

[0028] In a state in which the asbestos and the solidified carbon dioxide are inserted together into the through hole 121 of the gasket 120, the pressing means 110 pressurize the asbestos and the solidified carbon dioxide at the same time at both ends of the through hole 121. In the present exemplary embodiment, the pressing means 110 have a diamond shape, and have a constitution adopted to observe a change in asbestos components for each process through X-ray diffraction (XRD) while simultaneously obtaining high pressure. The pressure device itself is generally known as a diamond anvil cell (DAC) device.

[0029] In an exemplary embodiment of the present invention, the expensive DAC device is used to observe the effects of the present invention for each process through XRD. However, it is obvious to a person skilled in the art that the DAC device is not necessarily used under circumstances (in commercialization process) in which observation for each process is not required, and any kinds of pressure device (for example, a high-pressure cylinder device, and a high-pressure press device) may be adopted as long as high pressure is capable of being obtained.

[0030] The present invention is characterized in that heating and pressing are directly performed on the asbestos and the solidified carbon dioxide without chemical pre-treatment. It could be confirmed through microscopic observation that in the state in which the asbestos and the solidified carbon dioxide are inserted, when the asbestos and the solidified carbon dioxide are maintained at a pressure of 1 to 5 GPa and a temperature of 100 to 250° C., unique fiber tissue of the asbestos are destroyed. In particular, when the pressure is 4 GPa, and the temperature is 200° C., optical results could be obtained.

[0031] FIG. 5A is a microscope image of Tremolite through which detoxification is performed according to an exemplary embodiment of the present invention, and FIG. 5B is a microscope image of Chrysotile through which detoxification is performed according to an exemplary embodiment of the present invention.

[0032] As shown in FIGS. 5A and 5B, it could be confirmed that the asbestos through which the detoxification is performed according to an exemplary embodiment of the present invention completely lost its own unique fiber tissue. Upon considering that the toxicity to a human body caused by the asbestos comes from the unique fiber tissue morphology of the asbestos, it is determined that the toxicity to the human body is removed from the asbestos through which the detoxification is performed according to the present invention.

[0033] For comparison, water (H.sub.2O) instead of using the solidified carbon dioxide and the asbestos were inserted, and detoxification (heating and pressing) as described above was performed thereon. However, as a result, it could be confirmed that the fiber tissue were maintained as they are as shown in FIG. 6A and FIG. 6B. Accordingly, it could be confirmed that three essential configurations (carbon dioxide, pressure range, and temperature range) according to the present invention are factors which are necessarily required for the method of asbestos detoxification.

[0034] Upon reviewing a process of the detoxification method according to the present invention with reference to FIG. 4, even though it is possible to raise pressure and temperature at a time to the suggested ranges thereof (pressure of 1 to 5 GPa and temperature of 100 to 250° C.), it was confirmed that it was more effective to raise temperature and pressure by stages while alternately between heating and pressing, in view of conversion into more complete fibrous tissue morphology, and time and energy savings. That is, the process is divided into several steps until the temperature and the pressure are reached at the final desired temperature (Nth temperature) and the final desired pressure (Nth pressure). Then, the pressure and the temperature may be raised by applying a predetermined pressure and raising the temperature to a predetermined temperature for each step, and in a next step, applying a higher predetermined pressure than that of the previous step, and raising the temperature to a higher predetermined temperature than that of the previous step, i.e., alternately raising the pressure and the temperature by stages.

[0035] For example, in a state in which the asbestos and the solidified carbon dioxide are inserted into the pressure device 100, the pressure is firstly applied with 0.53 GPa corresponding to a first pressure. Then, the asbestos and the solidified carbon dioxide are heated to 160° C. corresponding to a first temperature in a state in which the pressure is not controlled, and maintained for 1 hour (see FIG. 7). Next, the pressure is applied with 0.84 GPa corresponding to a second pressure, and the asbestos and the solidified carbon dioxide are heated to 170° C. corresponding to a second temperature without controlling the pressure, and maintained for 1 hour. The pressing and the heating are continuously repeated as described above until the desired pressure and the desired temperature are reached. Specifically, the pressure is applied with 1.26 GPa, and the asbestos and the solidified carbon dioxide are heated up to 200° C. and maintained for 1 hour, and then the pressure is applied with 3.8 GPa, and the asbestos and the solidified carbon dioxide are heated up to 220° C. and maintained for 1 hour, and after that, the pressure is applied with 5.22 GPa, and the temperature is intactly maintained. Next, the heating and the pressing states are released.

[0036] In the above-description, there is provided an example in which the heating and the pressing are repeated by stages in order to reach the desired pressure state (1 to 5 GPa) and the desired temperature state (100 to 250° C.). However, the technical effects of the present invention are entirely obtained through the above-described pressure range (1 to 5 GPa) and the temperature range (100 to 250° C.), and accordingly, the number of steps in which the heating and the pressing are repeated corresponds to a technical matter that can be selected and applied by a person skilled in the art as needed.

[0037] FIG. 7 shows XRD analysis results for each step obtained by inserting Tremolite and the solidified carbon dioxide into the pressure device and repeating the heating and the pressing for each step as described above.

[0038] It could be appreciated that positions of peaks were not significantly changed in the state in which the heating and the pressing are maintained. That is, the positions of the peaks of the XRD analysis results before the detoxification, and the positions of the peaks of the XRD analysis results after the final detoxification were almost not changed. It could be confirmed from the above analysis results that the intrinsic component of the asbestos was not chemically changed at all.

[0039] That is, according to the related art, the asbestos is detoxified by using carbon dioxide, and the component itself of the asbestos is converted into the carbonate mineral through chemical treatment. On the contrary, according to the detoxification of the present invention, the component itself of the asbestos is not specifically changed, but only the fiber tissue was destroyed. Accordingly, even though the toxicity to the human body caused by the asbestos is removed, many parts of excellent properties of the asbestos are maintained as they are. Consequently, the present technology may refer to a technology of recycling the asbestos rather than discarding the asbestos as a waste material.

[0040] In particular, the method of asbestos detoxification of the present invention includes directly pressing and heating the asbestos together with the solidified carbon dioxide without chemical pre-treatment, which is unlike the related art, such that another concern for environmental contamination that may be resulted from the chemical pre-treatment may be prevented in advance.