WO1994008661A9 - Product and method for treating asbestos - Google Patents
Product and method for treating asbestosInfo
- Publication number
- WO1994008661A9 WO1994008661A9 PCT/US1993/009682 US9309682W WO9408661A9 WO 1994008661 A9 WO1994008661 A9 WO 1994008661A9 US 9309682 W US9309682 W US 9309682W WO 9408661 A9 WO9408661 A9 WO 9408661A9
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- asbestos
- alkali
- naoh
- waste
- fibers
- Prior art date
Links
- 239000010425 asbestos Substances 0.000 title claims abstract description 105
- 229910052895 riebeckite Inorganic materials 0.000 title claims abstract description 105
- 239000000835 fiber Substances 0.000 claims abstract description 50
- 239000002699 waste material Substances 0.000 claims abstract description 38
- 239000003513 alkali Substances 0.000 claims abstract description 27
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 10
- 230000003000 nontoxic Effects 0.000 claims abstract description 5
- 231100000252 nontoxic Toxicity 0.000 claims abstract description 5
- HEMHJVSKTPXQMS-UHFFFAOYSA-M sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 106
- KWYUFKZDYYNOTN-UHFFFAOYSA-M potassium hydroxide Inorganic materials [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 150000007529 inorganic bases Chemical class 0.000 claims description 3
- 230000001603 reducing Effects 0.000 claims description 3
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 239000007795 chemical reaction product Substances 0.000 claims 3
- 239000002245 particle Substances 0.000 claims 1
- 239000000377 silicon dioxide Substances 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 21
- 229910052620 chrysotile Inorganic materials 0.000 description 15
- CWBIFDGMOSWLRQ-UHFFFAOYSA-N trimagnesium;hydroxy(trioxido)silane;hydrate Chemical compound O.[Mg+2].[Mg+2].[Mg+2].O[Si]([O-])([O-])[O-].O[Si]([O-])([O-])[O-] CWBIFDGMOSWLRQ-UHFFFAOYSA-N 0.000 description 15
- 238000004220 aggregation Methods 0.000 description 14
- 230000002776 aggregation Effects 0.000 description 14
- 238000000034 method Methods 0.000 description 12
- ULEFFCDROVNTRO-UHFFFAOYSA-N trimagnesium;disodium;dihydroxy(oxo)silane;iron(3+) Chemical compound [Na+].[Na+].[Mg+2].[Mg+2].[Mg+2].[Fe+3].[Fe+3].O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O.O[Si](O)=O ULEFFCDROVNTRO-UHFFFAOYSA-N 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- VTHJTEIRLNZDEV-UHFFFAOYSA-L Magnesium hydroxide Chemical compound [OH-].[OH-].[Mg+2] VTHJTEIRLNZDEV-UHFFFAOYSA-L 0.000 description 6
- 238000009413 insulation Methods 0.000 description 6
- 238000004132 cross linking Methods 0.000 description 5
- 239000000347 magnesium hydroxide Substances 0.000 description 5
- 229910001862 magnesium hydroxide Inorganic materials 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 4
- 210000004027 cells Anatomy 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000011159 matrix material Substances 0.000 description 3
- 238000004098 selected area electron diffraction Methods 0.000 description 3
- -1 that is Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 210000001280 Germinal Center Anatomy 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N HCl Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
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- VHUUQVKOLVNVRT-UHFFFAOYSA-N ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 2
- 239000000908 ammonium hydroxide Substances 0.000 description 2
- 239000002585 base Substances 0.000 description 2
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- 230000001809 detectable Effects 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 2
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- 229920000742 Cotton Polymers 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L Magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 210000001616 Monocytes Anatomy 0.000 description 1
- WYTGDNHDOZPMIW-UHOFOFEASA-O O=C(OC)C=1[C@@H]2[C@@H]([C@@H](C)OC=1)C[n+]1c(c3[nH]c4c(c3cc1)cccc4)C2 Chemical group O=C(OC)C=1[C@@H]2[C@@H]([C@@H](C)OC=1)C[n+]1c(c3[nH]c4c(c3cc1)cccc4)C2 WYTGDNHDOZPMIW-UHOFOFEASA-O 0.000 description 1
- 239000004698 Polyethylene (PE) Substances 0.000 description 1
- 229920000388 Polyphosphate Polymers 0.000 description 1
- FKHIFSZMMVMEQY-UHFFFAOYSA-N Talc Chemical compound [Mg+2].[O-][Si]([O-])=O FKHIFSZMMVMEQY-UHFFFAOYSA-N 0.000 description 1
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- NBIIXXVUZAFLBC-UHFFFAOYSA-K [O-]P([O-])([O-])=O Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
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- YLUIKWVQCKSMCF-UHFFFAOYSA-N calcium;magnesium;oxygen(2-) Chemical compound [O-2].[O-2].[Mg+2].[Ca+2] YLUIKWVQCKSMCF-UHFFFAOYSA-N 0.000 description 1
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- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 1
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- 239000008188 pellet Substances 0.000 description 1
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- 230000003134 recirculating Effects 0.000 description 1
- 229910052616 serpentine group Inorganic materials 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N silicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 229910052604 silicate mineral Inorganic materials 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
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- 231100000041 toxicology testing Toxicity 0.000 description 1
- KNXVOGGZOFOROK-UHFFFAOYSA-N trimagnesium;dioxido(oxo)silane;hydroxy-oxido-oxosilane Chemical compound [Mg+2].[Mg+2].[Mg+2].O[Si]([O-])=O.O[Si]([O-])=O.[O-][Si]([O-])=O.[O-][Si]([O-])=O KNXVOGGZOFOROK-UHFFFAOYSA-N 0.000 description 1
- 238000004017 vitrification Methods 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Abstract
A method for eliminating the hazardous properties of asbestos waste is provided. The waste is treated with alkali and heat to crosslink the asbestos fibers and form a nontoxic, amorphous, silica aggregate. An apparatus for carrying out the method is also provided.
Description
PRODUCT AND METHOD FOR TREATING ASBESTOS
The present invention relates generally to the safe disposal of asbestos waste, that is, asbestos and asbestos-containing waste materials. In particular, the invention provides a method and apparatus for eliminating the hazardous properties of asbestos waste by altering the morphology of asbestos fibers.
BACKGROUND OF THE INVENTION
Disposal of waste material is one of the major problems facing modern society. The problem is particularly acute with regard to asbestos waste, not only because asbestos is toxic to man and animals but also because this material has been in wide use for many years and the resulting volume of asbestos waste being generated is substantial.
It is a common practice to landfill asbestos waste even though parties who generate such waste remain responsible for its deposition in landfills. Thus, to reduce the liabilities attendant on this method of disposal, the abatement industry must operate in compliance with the expensive and labor intensive disposal procedures set forth in the Comprehensive Environmental Response Compensation and Liability Act.
As an alternative to the direct disposal of asbestos waste in landfills, a high temperature vitrification process has been developed. While such a process converts asbestos to a form which is apparently harmless, this procedure requires large amounts of energy and is economically not practical.
Other asbestos treatments are known, but do not produce materials that are suitable for waste disposal. For example, Charleton, U.S. Patent No. 1,256,296 discloses the treatment of "teased" asbestos fibers with magnesia or dolomitic lime at an elevated temperatures and superatmospheric pressure, to produce fibers which retain their original appearance but have a greater tendency to ma . This product has applications similar to those of ordinary asbestos, and is described as a superior packing or insulation material. Thus, Charleton is concerned with asbestos use, not asbestos removal. Charleton preserves the fibrous nature of asbestos, he does not destroy it.
Jackson, U.S. Patent No. 1,254,230 discloses that naturally-occurring chrysolite and other silicates can be decomposed into acid-soluble alkaline and magnesium silicate materials by treatment with a large excess of caustic alkali at temperatures of about 350 °C to about 600 °C and higher, for a period of about 2 hours. According to Jackson, these temperatures require the use of caustic alkali, not carbonates, and a large excess of alkali of more than 2:1, preferably 4:1 is essential. The silicates produced by this process are extracted with water, filtered, and dissolved in acid to produce a useful soluble magnesium salt, such as magnesium sulfate. This process and product is far removed from the treatment of asbestos to form a non-fibrous material for waste removal purposes.
U.S. Patent No. 3,94,184 of Harada et al. discloses a method for converting chrysotile asbestos to a composition rich in magnesium hydroxide, by repeated treatments in a pressure chamber with a 20 to 60% solution of potassium hydroxide at 150 to 200 °C for 20 hours per treatment. The treated asbestos is useful as a potassium hydroxide resistant mat material for a fuel cell matrix in a hydrogen-oxygen fuel cell. In particular, Harada teaches that the morphology of the asbestos reaction can be maintained fibrous, so that the
desirable flexibility and capillarity for a fuel cell matrix mat is maintained. The final material is composed of about 80 to 90 percent magnesium hydroxide fibers by weight, and the remainder consists of untreated asbestos fibers. The magnesium hydroxide fibers, which are crystalline, retain the morphology of the original asbestos fibers. Harada also teaches that more severe reaction conditions result in a less fibrous and desirable product.
Other surface modification of asbestine minerals have also attracted attention in prior studies. These modifications consist of: coating the surface with phosphate, polyphosphate, magnesium carbonate or oxides of polyvalent metals. For example, Flowers, U.S. Patent No. 4,328,197 discloses a metal-micelle polymer coating for asbestos which is said to reduce the toxicity of asbestos materials. Some procedures have consisted of coating fibers with organic detergent to gain fiber dispersion. These methods, though interesting, are relatively costly and complex, and have not achieved meaningful commercial recognition. Accordingly, it is an object of the present invention to provide a low energy, economical method wherein the hazardous properties of asbestos are eliminated.
It is a further object of the invention to provide a method wherein asbestos waste is rendered non-toxic and may be disposed of in landfills with a lower classification of waste (e.g. as designated in certain areas as a Type II waste) .
It is a further object of the invention to provide an apparatus for carrying out such a method.
SUMMARY OF THE INVENTION
The present invention meets these and other objectives by providing a method for eliminating the hazardous properties of asbestos waste by altering the morphology of asbestos fibers. The method includes the steps of reacting
asbestos waste with alkali at a concentration of about 10M and a temperature of about 300°C. This produces a melding of fibers to form amorphous silica aggregates. The invention further provides an apparatus for carrying out this process . The apparatus includes a reactor in which asbestos waste is treated with alkali at relatively low temperatures and means for loading and recirculating alkali used in the process.
BRIEF DESCRIPTION OF FIGURES
Figure 1 depicts the effect of fiber density by comparing pelletized and non-pelletized reactions with NaOH
(1-20M) at 200°C, for 30 minutes. The control represents values where no NaOH was present in the reaction mixture.
The values are expressed as mean Fiber Counts Per
Photographic Field (Federal Register Vol. 52, No. 210, October 30, 1987; Counting Guidelines Used in Determining Asbestos Structures) .
Figure 2 shows the effect of various temperatures on the chemical alteration of chrysotile. This graph demonstrates that temperatures above 200°C and molar concentrations of NaOH above 1M were effective in the molecular alteration of fiber structures. The plateau of values at 50° to 100°C indicates that there may be fibers varying in resistance to the conditions used. This was also true for crocidolite and amosite asbestos at temperatures of 50° to 100°C.
Figure 3 depicts the effect of temperature and molar concentration of NaOH on crocidolite.
Figure 4 depicts the effect of temperature and molar concentration of NaOH on amosite. Figure 5 shows that asbestos does not leach-out or reform once it has been chemically altered by NaOH and mild heat (200°C) for 30 minutes. Figures 1 to 4 show a precipitous drop in fiber counts even at 1M NaOH. Figure 5
shows that, even at 68 days, there was no conversion back to the fibrous structures.
Figure 6 shows transmission electron microscope (TEM) images of untreated chrysotile asbestos fibers. Figure 7 shows amorphous granules resulting from treatment of chrysotile fibers with 10M NaOH at 300°C for 30 minutes. No detectable fibers are present.
Figure 8 shows the Selected Area Electron Diffraction (SAED) pattern in which a crystal image is used to define the presence of asbestos (e.g. in a sample such as that used in Fig. 6) .
Figure 9 shows the lack of any SAED crystalline structure in the NaOH treated sample (from Fig. 7) .
Figure 10 compares three different alkalis, NaOH, KOH, and NH30H which are used under standard conditions of 300°C at 30 minutes. The molar concentration of each was 1, 5 and 10M. It was apparent that NaOH is superior to KOH and NH30H under these conditions. Ammonium hydroxide was without detectable effect. Figure 11 shows resulting asbestos aggregation on refractory (firebrick) surfaces. The presence of other masonry materials found in abatement work were shown not to interfere with the chemical effect of NaOH and mild heat on asbestos fiber aggregation. Figure 12 shows the rate of aggregation of chrysotile fibers at 300°C with 10M NaOH.
Figure 13 shows the rate of aggregation of asbestos fibers taken from steam pipe insulation.
Figure 14 depicts the amount of NaOH required to aggregate 80 grams of damp (amended water) steam pipe insulation.
Figure 15 illustrates the effect of materials used in abatement work on the rate of aggregation.
Figure 16 is a bar graph showing that chrysotile.. crocidolite and amosite are aggregated extensively at 10M NaOH at 300°C.
Figure 17 shows in schematic representation a reactor for chemically cross-linking asbestos fibers.
DETAILED DESCRIPTION OF THE INVENTION
The invention is described with reference to several examples. It will be recognized, however, that the invention is not limited to any particular examples or embodiments and may be practiced broadly by persons of ordinary skill in the pertinent art or arts.
Chemical Composition & Characteristics of Asbestos
The term asbestos is generally applied to a group of naturally occurring fibrous silicate minerals that are commercially important due to their fibrous characteristics. There are three principal types of asbestos which have appeared in world-wide commerce. These are chrysotile from the serpentine group and crocidolite and amosite from the amphibole group. Of these, chrysotile accounts for 95% of the world's asbestos production. Chrysotile is a hydrated magnesium silicate with the general formula Mg3Si203(0H)4. Structurally, chrysotile consists of sheets rolled up and formed from two layers. The first layer is a continuous matrix of silica (Si02) tetrahedra. This layer is bound through oxygen atoms held in common with a second layer of Mg(OH)2 octahedral. The shells or walls of asbestos fibers are composed of a number of individual sheets contorted into scrolls with magnesium hydroxide layers on the outside.
It has now been discovered that the use of mild alkali and relatively low temperatures will render asbestos harmless, without resorting to complex coating procedures or high-energy disposal means. Moreover, it has been discovered
that this treatment changes the fiber morphology to a non-crystalline amorphous structure.
All forms of asbestos break down into simpler components when heated to temperatures of 1,000°C or higher. The reactivity of asbestos to some acids and alkalis has been studied, and all varieties of asbestos will resist prolonged attack by strong alkali (e.g. 5M NaOH) to temperatures at least as high as 100°C. Surprisingly,it has now been discovered that asbestos fibers treated with a combination of relatively moderate alkali and temperature conditions will undergo substantial cross-linking or aggregation. The morphology of these fibers is permanently altered by this treatment and an insoluble, amorphous, silicate aggregate results.
Treatment for Waste Disposal
This method of cross-linking asbestos fibers was tested with asbestos (chrysotile, crocidolite, and amosite) contained in asbestos waste. This included materials arising from abatement work, such as Tyvek suits, cotton towels, disposable gloves, polybags, fiberglass, polyethylene sheets, wood, concrete, refractory from boilers, and metal bands. The data presented below shows that an alkaline reaction conducted at relatively low temperatures (100°C - 300°C) is able to render asbestos into amorphous silicates even when the asbestos forms only a part of such waste materials.
All laboratory analyses were conducted by licensed personnel in a rigid plastic glove box with exhaust through a HEPA filter at 600 liters per minute and then expelled through the roof via an 8 inch diameter duct (fiber counts in the exhaust were less than 0.0045 f/cc) .
According to the present invention, asbestos waste was treated with alkali at temperatures ranging from 50°C to about 400°C with the optimal temperature being about 300°C with respect to economy. Preferably, the alkali is a
univalent base such as NaOH or KOH, but mixtures may also be used. It will be understood, however,, that the invention is no way limited to this regard and that a broad range of both organic and inorganic bases may be employed. The alkali was present in concentrations ranging from about 1M to 20M, most preferably 10M for economy reasons. The reaction is allowed to proceed for periods of up to 60 minutes with the preferred duration being about 20 to about 30 minutes depending on the concentrations of alkali used.
Analysis of Treated Waste
As seen in Figure l, the amount of asbestos, whether concentrated in a pellet or as a loose suspension, did not affect the rate of reaction. A marked reduction in fiber count is observed as the result of these treatments. The rate of aggregation as a function of temperature and concentration of NaOH was determined for chrysotile (Figure 2) , crocidolite (Figure 3) , and amosite (Figure 4) . It is apparent that there is a stoichiometric relationship between temperatures and concentrations of NaOH. The data shown in Figure 5 indicates that once the aggregates are formed they are not dissolved or returned to original form.
Figures 6 through 9 were generated by transmission electron microscopy (TEM) and together illustrate the dramatically altered morphology of asbestos fibers after treatment according to the invention. The highly developed fibrous morphology of chrysotile asbestos illustrated in Figure 6 is typical of all forms of asbestos prior to treatment with alkali and heat. Transmission electron microscopy was also used to generate the data shown in Figure
7, which shows that the asbestos morphology has clearly been altered after treatment at 300°C with 10M NaOH. The fibers have cross-linked to form an amorphous silica aggregate which
is granular and can no longer be characterized as fibrous or as asbestos.
Molecular changes associated with altered morphology have shown that treated asbestos will no longer polarize light, has an altered X-ray spectra of Mg, Fe and Si, and has no crystalline structure when examined by electron diffraction. Tests with crocidolite and amosite asbestos produced similar results.
The data presented in these figures clearly indicates a change from a fibrous to non-fibrous morphology.
X-ray analysis further revealed a shift in atomic ratio of
(Mg + Fe) Si, as shown in Table 1 for treatment with NaOH or
Hcl.
TABLE 1 X-RAY ANALYSIS SPECTRA
As stated above, a broad range of both organic and inorganic bases may be employed in the present invention. Figure 10 illustrates a comparison of three different alkalis, NaOH, KOH,a and NH30H, all of which were used at 300° for 30 minutes. The molar concentrations of each was 1, 5, and 10M. It is apparent from Figure 10, that while KOH is entirely suitable for the present invention, NaOH achieved more extensive aggregation of the fibers under these particular reaction conditions. Ammonium hydroxide produced only a minor degree of cross-linking, and it is believed that the ammonium ions may have volatilized off during the early phase of heating. Accordingly, volatile bases such as NH30H are probably not as suitable for the present invention. Hydrochloric acid did not produce any of the molecular changes seen with NaOH (change in fiber morphology) .
The effect of additional materials mixed with asbestos on the present invention is further illustrated in Figure 11. The sample used in Figure 11 was taken from an asbestos-containing refractory surface. The presence of masonry materials contained in the sample was shown not to interfere with the chemical effect of alkali (e.g. NaOH) and heat on fiber aggregation. It has been found that the cross-linking reaction proceeds more efficiently if the bulk size of the asbestos waste is reduced prior to treatment. Reducing the bulk size of the waste by, for example, grinding, crushing or shredding increases the surface area of the waste in contact with the alkali at any given point in the reaction.
Figure 12 shows the rate of aggregation of chrysotile fibers at 300°C with 10M NaOH. Under these conditions, the asbestos fibers are eliminated in three stages: about 10 percent or less of the fibers react during
the first 10 minutes or so of treatment, about 60 percent of the fibers are rapidly eliminated during the second 10 minutes, and the remaining 30 percent or so were more slowly eliminated in about the last ten minutes. No residual fibers were present after 30 minutes.
Asbestos fibers taken from steam pipe insulation can be aggregated much more rapidly under similar conditions. As shown in Figure 13, all of the fibers were aggregated by 20 minutes when heated at 300°C, and all but about 5 percent or less were eliminated in the first ten minutes. The lower starting level of 64% (compared to Figure 12) was due to samples containing other particulate material. In general, the presence of other particulate material is indicated by a lower starting point or control value, but this does not alter the rate of aggregation.
Asbestos fibers may be wet or damp, articularly when taken from steam pipe insulation. Figure 14 depicts the amount of NaOH required to aggregate 80 grams of damp
(amended water) steam pipe insulation. As shown, equal weights of damp asbestos and NaOH eliminated all residual fibers.
Other materials may be present when asbestos material is removed from a contaminated site, and the abatement process itself may add materials to the asbestos waste. The affect of various materials used in abatement work on the rate of asbestos aggregation according to the invention was evaluated. These materials had no affect on aggregation or on the new method of aggregating asbestos fibers when equal weights of NAOH were used. The tested materials were Tyvek, poly bags, sweeping compound, and HEPA filters. The results are shown in Figure 15.
The preferred working conditions, according to the invention, are 10M NaOK at 300°C. These conditions produce rapid, efficient, cost-effective aggregation of potentially harmful asbestos fibers into harmless melded aggregates. As
shown in Figure 16, these conditions are suitable for chrysotile, crocidolite and amosite asbestos.
Apparatus for Processing Asbestos Waste
An apparatus according to the invention is shown in Figure 17. The apparatus includes a stack (1), an after burner (2) , a scrubber (3) , a reaction chamber (4) , an alkaline charge (5) , and a two-stage ram (6) . In operation, asbestos containing waste is introduced to a hopper (7) and mixed with an aqueous solution of alkali. The contents of hopper (7) are discharged by ram (6) into the reaction chamber (4) after compaction. The ram or piston (6) is then withdrawn to accept the next charge of waste. The asbestos containing material is aggregated within chamber (4) by heat from an external source (not shown) in the presence of alkali. The vapor phase generated by this process is condensed in scrubber (3) and the liquid phase is recycled to hopper (7) through water return (8) . Other gases are expelled through stack (1) and are eliminated by after burner (2) . The alkaline solution is recycled to hopper (7) by alkaline return (9) . The treated waste is removed via discharge chamber (10) , and may be washed to remove and recirculate additional alkali via alkaline return (9) . In practice, the solid and gas materials discharged from the apparatus (i,e at stack (1) and chamber (10)) are monitored by TEM to establish and ensure contaminate-free operation.
The asbestos containing material treated in this apparatus becomes aggregated and amorphous; it no longer has the properties of asbestos waste. This detoxified material can safely be brought to landfills or used for other purposes.
Toxicity Studies
To establish that asbestos treated with alkali (e.g. NaOH) and mild heat has been stripped of its toxic
properties, three animal studies were conducted. Two of these studies consisted of intradermal implants (200 S/D rats) of filters containing asbestos treated with NaOH and appropriate controls or intradermal injections (10ml) of treated asbestos and controls. The third study consisted of intraperitoneal injection of treated asbestos in CD-I mice (25-30g, SPF) . In all cases analyses were made by preparing histologic sections (H+E, 400x) . Table 2 shows that rats inoculated with treated asbestos were free of typical asbestos-induced lesions.
TABLE 2
Mice inoculated with treated asbestos or untreated control asbestos were euthanized at intervals of up to 48 hours after injection. These animals were scored for the
presence or absence of histocytes in the splenic follicles or in the thymus-dependent areas surrounding the central arterioles. Untreated asbestos produced large accumulations of histocytes (germinal centers) in both the marginal and thymus-dependent areas, while the treated asbestos produced no distinct response. The treated asbestos inocula produced no increase in follicle or germinal centers. This procedure is described in Kenyon, A.J. Comparison of early splenic changes associated with virus replication in murine monocytes, Am. J. Vet. Res. 45:1054 (1984).
Claims
1. A method for treating asbestos waste comprising reacting asbestos waste at temperatures below about 400 °C with an alkali solution having a molar concentration effective to convert asbestos fibers into nontoxic amorphous silica aggregates.
2. The method of claim 1 wherein the temperature is in the range of about 100°C to about 400°C.
3. The method of claim 1 wherein the temperature is about 300 °C.
4. The method of claim 1 wherein the alkali is a univalent inorganic base.
5. The method of claim 1 wherein the alkali is selected from the group consisting of NaOH, KOH and mixtures thereof.
6. The method of claim 1 wherein the alkali is provided as an aqueous solution having a concentration ranging from about 1M to about 20M.
7. The method of claim 1 wherein the concentration of the alkali in the solution is about 10M.
8. The method of claim 1 wherein the step of reacting is preceded by the step of reducing the particle size of the asbestos waste to increase its surface area.
9. The method of claim 1, wherein the reaction is conducted for a period of time ranging from about ten minutes to about 1 hour.
10. A method for treating asbestos waste comprising reacting the waste at about 100 to 400 °C with an alkali solution having at least one of NaOH and KOH in a molar concentration of about 1 to 20M, for a period of time ranging from about ten minutes to about 1 hour.
11. Nontoxic amorphous silica aggregates comprising the reaction product of asbestos fibers and an alkali.
12. Nontoxic amorphous silica aggregates comprising the reaction product of asbestos fibers and an aqueous alkali solution, at temperature of about 100 to about 400 °C.
13. The aggregates of claim 11, wherein the alkali is at least one of NaOH and KOH in a concentration of about 1M to 20M.
14. The aggregates of claim 12, wherein the alkali is at least one of NaOH and KOH in a concentration of about 1M to 20M.
15. The aggregates of claim 14, wherein the reaction product is obtained after a period of time ranging from about 10 minutes to about 1 hour.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU53564/94A AU5356494A (en) | 1992-10-08 | 1993-10-06 | Product and method for treating asbestos |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US95865092A | 1992-10-08 | 1992-10-08 | |
US958,650 | 1992-10-08 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO1994008661A1 WO1994008661A1 (en) | 1994-04-28 |
WO1994008661A9 true WO1994008661A9 (en) | 1994-06-09 |
Family
ID=25501152
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1993/009682 WO1994008661A1 (en) | 1992-10-08 | 1993-10-06 | Product and method for treating asbestos |
Country Status (2)
Country | Link |
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AU (1) | AU5356494A (en) |
WO (1) | WO1994008661A1 (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19501128A1 (en) * | 1995-01-03 | 1996-07-04 | Kokoschko Rene Dipl Krist | Treating mechanically processed raw materials contg. asbestos |
DE69605927T2 (en) * | 1995-06-16 | 2000-06-15 | Gerard Debailleul | METHOD AND DEVICE FOR TREATING ASBESTIC CONTAINING WASTE |
EP0887088B1 (en) * | 1997-06-27 | 2003-10-01 | Gérard Debailleul | Process and installation for the treatment of asbestos-containing absorbing mass in gas bottles |
US7476194B2 (en) * | 1999-10-20 | 2009-01-13 | Studsvik, Inc. | In-container mineralization |
US7531152B2 (en) | 2000-10-19 | 2009-05-12 | Studsvik, Inc. | Mineralization of alkali metals, sulfur, and halogens |
EP1671682A1 (en) * | 2004-12-20 | 2006-06-21 | Inertec | Asbestos degradation process with alkali metal hydroxides |
US7939705B2 (en) | 2005-06-30 | 2011-05-10 | Ari Technologies, Inc. | System and method for treating asbestos |
EP1919637B1 (en) * | 2005-06-30 | 2011-09-21 | Ari Technologies, Inc. | System and method for accelerating the conversion of asbestos in the process of mineralogical conversion |
US20160379727A1 (en) | 2015-01-30 | 2016-12-29 | Studsvik, Inc. | Apparatus and methods for treatment of radioactive organic waste |
CN109553385B (en) * | 2018-12-19 | 2021-09-21 | 西南科技大学 | Chrysotile tailing ceramsite and preparation method thereof |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3914184A (en) * | 1973-10-17 | 1975-10-21 | Us Air Force | Method for converting crysotile asbestos |
JPH01171685A (en) * | 1987-12-25 | 1989-07-06 | Mitsui Eng & Shipbuild Co Ltd | Treatment of waste containing asbestos |
US5085838A (en) * | 1989-05-25 | 1992-02-04 | Western Research Institute | Thermal modification of asbestos |
ES2067750T3 (en) * | 1989-06-29 | 1995-04-01 | Roger B Ek | MINERALOGICAL CONVERSION OF ASBESTOS WASTE. |
ATE132403T1 (en) * | 1992-03-23 | 1996-01-15 | Lemmerbrock Karl Heinrich | METHOD FOR DISPOSAL OF ASBESTOS OR MATERIALS CONTAINING ASBESTOS |
-
1993
- 1993-10-06 AU AU53564/94A patent/AU5356494A/en not_active Abandoned
- 1993-10-06 WO PCT/US1993/009682 patent/WO1994008661A1/en active Application Filing
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