CH686765A5 - Process for intensified efforts depletion of heavy metal compounds in the thermal inert of heavy metal residues. - Google Patents

Description

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CH 686 765 A5

description

Numerous types of waste represent a high environmental hazard potential due to leachable heavy metals. Various studies have shown that under certain conditions, sintering or melting and vitrification can render non-flammable residues inert. The aim of thermal inerting is generally to integrate and immobilize environmentally relevant heavy metals in the glass or sinter matrix formed. The thermal inerting processes are suitable for the treatment of waste from group 3 of the waste types catalog (waste of mineral origin) and in particular the following residues from incineration plants:

Table 1:

Classification of the examined residues in the waste type catalog [LAGA information sheet waste types. State Working Group on Waste (LAGA) (ed.), Waste Management in Research and Practice 41, Erich Schmidt Verlag, Berlin (1992) 1-196; Ordinance for the determination of waste in accordance with Section 2 (2) of the Waste Act (Waste Determination Ordinance - AbfBestV). Straub, H .; Hösel, G .; Schenkel, W. (ed.), Müll-Handbuch 1, delivery 4/90, Erich Schmidt Verlag, Berlin (1964) code 0513; Ordinance for the determination of residues in accordance with Section 2 (3) of the Waste Act (Ordinance on the Determination of Residual Substances - RestBestV). Straub, H .; Hösel, G .; Schenkel, W. (ed.), Müll-Handbuch 1, delivery 4/90, Erich Schmidt Verlag, Berlin (1964) code 0514]

ASN number

designation

Disposal note

Category in need of monitoring

31308

Slag and ashes from waste incineration plants

-

I no

31309

Fly ash and dusts from waste incineration plants

HMD (only in special areas of the HMD) or SAD

II yes

31310

Slags from hazardous waste incineration plants

SAD or mono landfill

II yes

31311

Filter dust from special waste incineration plants

SAD (preference) or UTD

II yes

31312

Solid reaction products for waste gas purification from waste incineration plants

UTD (preference) or SAD

Yes

Various processes and furnaces have been developed for the thermal inertization of these residues and have been described in the literature. Table 2 shows an overview of the most important processes.

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Table 2:

Process for the thermal inertization of residues from waste incineration (references to this table on the next page)

method

Manufacturer

Residues

Oven type

Temperature in ° C

Combustion chamber process [1]

Von Roll

Slag and filter dust

Combustion chamber

1500-1750

Firing and melting process [2]

Babcock

Filter dust, fine fraction of the slag

Fired melting furnace

1400-1600

Cormin (Continuous Residual Mineralization) [1.3]

Pleq (Klöckner Humboldt Deutz system)

Sewage sludge, filter dust, boiler dust, fine fraction of the slag

Melting cyclone

1600

Deglor (Detoxification and Glassification of Residues) [4.5]

ABB, W + E Umwelttechnik

Filter dust

Electric oven (heated from above)

1300-1500

Flame chamber melting process [6,1,3]

Ebara Infilco, Kuboto (VW system)

Filter dust, slag, direct waste melt

Flame chamber furnace (double cylinder)

1300-1800

FosMelt [7]

Steinmüller / Horn / Messer Griesheim

Flying dust, kettle ash, slag

Fired melting furnace

1300-1500

Plasma melting process [8, 9]

Krupp-MAK

Filter dust

Plasma furnace

2000

RedMelt [7, 10]

Steinmüller, MAN GHH

Flying dust, kettle ash, slag

Arc furnace

1300

Slag treatment in a rotary tube [11]

Von Roll

slag

Rotary tube

Solur [12]

Lurgi + Sorg

Filter dust and residues from exhaust gas cleaning

Glass melting furnace with direct heating by resistance bars

1300-1400

All-electric melting process [3]

Jenaer Schmelztechnik Jodeit GmbH

Residues of the exhaust walls

Glass melting furnace with direct heating by molybdenum electrodes

1400

[1] Faulstich, M .: inertization of solid residues from waste incineration. Waste Management Journal 1, No. 7/8 (1989) 21-56

[2] Horch, K .; Schetter, G .; Räbiger, W .: Burn-smelting process for glazing slag and filter ash. VDI seminar, No. 43-76-01, slag processing, recycling and disposal (1992) 1384

[3] Gleis, M .; Hoffmann, G .: Treatment methods to improve the environmental compatibility of residues from the incineration of household waste. Training center for health and environmental protection Berlin (ed.), Seminar residues from waste incineration plants 31 (1992) 43-61

[4] Haitiner, E. W .: Detoxify and recycle filter dust. Waste disposal technology (1990) 45-48

[5] Federal Minister for the Environment, Nature Conservation and Nuclear Safety: Seventeenth Ordinance implementing the Federal Immission Control Act of November 23, 1990 (Ordinance on Incineration Plants for Waste and Similar Combustible Substances - 17th BlmSchV). Waste Management Journal 3 (1991) 110-119

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[6] Fujimoto, T .; Shin, K .; Shioyama, M .: Preparation of combustion residues using the high-temperature melting process. Rubbish and Waste 21, No. 2 (1989) 64-70

[7] Faulstich, M .; Freudenberg, A .; Kley, G .; Köcher, P .; Schuhmacher, W .: Process for further thermal inerting of residues from waste incineration plants. VDI seminar, No. 43-76-01, slag processing, recycling and disposal (1992) 1423

Klein, H .: Thermal processing of flight and filter dusts from waste incineration plants using plasma furnace technology. Federal Ministry for Research and Technology (BMFT) (ed.), Knupp MaK (1989) 1-40

[9] Anonymus: filter dust is destroyed with plasma melt. Chemical Rundschau 9 (1990)

[10] Köcher, P .; Kley, G .; Freudenberg, A .; Faulstich, M .: Thermochemical treatment of waste incineration residues. Thomé Kozmiensky, K. J. (ed.), Reactors for thermal waste treatment, EF Verlag für Energie und Umwelttechnik, Berlin (1993) 267-281

[11] Brunner, M .: Von Roll slag treatment in a rotary kiln. VDI seminar, No. 43-76-01, slag processing, recycling and disposal (1992) 1389

[12] Mayer-Schwinning, G .; Merlet, H .; Pieper, H .; Zschocher, H .: Glazing Process for Inerting Residue Products from Pollutant Removal in Thermal Waste Disposal Plants. VGB Kraftwerkstechnik 70, No. 4 (1990) 332-336

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CH 686 765 A5

To optimize glass formation, additives have been reported in the literature, mostly substances with a high silicate content, which are added to the residues [Mayer-Schwinning, G .; Merlet, H .; Pieper, H .; Zschocher, H .: Glazing Process for Inerting Residue Products from Pollutant Removal in Thermal Waste Disposal Plants. VGB Kraftwerkstechnik 70, No. 4 (1990) 332-336]. By adding silicate-containing slag to filter dust from quasi-dry flue gas cleaning, glasses were obtained which, owing to the high proportion of calcium compounds from flue gas cleaning, cannot be glazed without additives [Gohlke, 0 .; Bieniek, D .; Melerò, R .; Kettrup, A .: Vitrification of residues from municipal waste incinération plants. Fresenius Environmental Bulletin 1 (1992) 191-196].

When glazing, however, the evaporation of heavy metal compounds must always be taken into account. Evaporation may be desirable, on the one hand, because a glass or sintered product protected by heavy metals with a lower leaching potential is obtained, on the other hand, however, heavy metal concentrates are obtained when the exhaust gas is cleaned, which can only be stored or recycled under special safety precautions.

Methods have been described, in particular for the glazing of filter dusts, which are carried out by special technical measures, e.g. Heating the melt from above, striving to deplete heavy metals by evaporation [Jochum, J .; Jodeit, H .; Wieckert, C .: ABB smelting process for the detoxification of filter dusts from waste incineration plants. Reprint ABB Research Center, CH-5405 Baden (1990); Jochum, J .; Schmidl, E .; Simon, F.-G .; Wieckert, C .: Carrying out pilot tests for the treatment and disposal of filter dust from waste incineration plants. ABB, Baden (CH) (1990) 1-60; Baccini, P .; Stämpfli, D .; Gamp, E .; Hofer, P .; Kläntschi, N .; Vonmont, H .: Material flow analysis of the thermal treatment of electrostatic filter dust by the pilot plant of the ABB in the KVA of the KEZO in Hinwil. EAWAG, Dübendorf (CH) (1990) 1-28]. The evaporated heavy metals are separated in filter systems as condensates or heavy metal concentrates and can be processed metallurgically or deposited underground. Despite these developments in furnace construction, conventional resistance-heated furnaces for the glazing of filter dusts from waste incineration plants could not meet the limits of the Swiss “Inert Substance Ordinance” [Federal Department of Home Affairs: Technical Ordinance on Waste (1990)].

In a test facility, approx. 95% of the lead, 50% of the zinc and 40% of the copper were evaporated during the glazing of filter dusts [Jochum, J .; Schmidl, E .; Simon, F.-G .; Wieckert, C .: Carrying out pilot tests for the treatment and disposal of filter dust from waste incineration plants. ABB, Baden (CH) (1990) 1-60]. According to the Swiss Technical Ordinance on Waste (“Swiss Inert Substance Ordinance”), an inert substance must not exceed the limit values shown in Table 2 [Federal Department of Home Affairs: Technical Ordinance on Waste (1990)].

Table 3:

Heavy metal limit values for inert substances in Switzerland and heavy metal contents of glazed filter dusts (in mg / kg)

Heavy metal

Limit value for inert substances

Heavy metal content in the glazing product

lead

500

350

cadmium

10th

5

copper

500

130

nickel

500

<50

mercury

2nd

<0.1

zinc

1000

7900

Other processes achieve even greater evaporation through the use of special plasma ovens, with which temperatures of over 2000 ° C can be reached [Klein, H .: Thermal processing of fly and filter dusts from waste incineration plants using plasma furnace technology. Federal Ministry for Research and Technology (BMFT) (ed.), Krupp MaK (1989) 1-40].

From Table 2 it can be seen that e.g. a filter dust glazed in conventional resistance-heated ovens does not meet the requirements as an inert substance in the sense of the Swiss technical regulation on waste due to the high zinc and lead content. This has far-reaching consequences for landfilling and recycling.

This problem is solved by the method listed in claim 1. The advantages achieved with the invention consist in particular in that, due to the additives, the glasses or sintered products obtained have a reduced heavy metal content and thus have better elution properties. The limits of the Swiss technical ordinance on waste can therefore also be used with fossil fuels or with electrically heated furnaces at temperatures between 1100 ° C and

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1500 ° C can be reached without having to resort to the complex and energy-intensive high-temperature plasma furnaces.

An advantageous embodiment of the invention is specified in claim 2. By using additives that contain hydrates, carbonates, sulfates or sulfites, a release of gases is achieved, which can lead to stripping of the heavy metal compounds.

An advantageous embodiment of the invention is specified in claim 3. By using residues containing hydrates, carbonates, sulfates or sulfites, waste streams are combined and transformed into usable glasses or sintered products. The heavy metal-containing residue allows the formation of a glass or sinter product with good immobilization of remaining heavy metal compounds, while the «gas-forming» additive enables an optimized heavy metal depletion of the glass or sinter product.

An advantageous embodiment of the invention is specified in claim 4. Thermal analyzes of a filter dust from a quasi-dry flue gas cleaning system (FSQT) in Figure 1 show an example of the decomposition of hydrates, carbonates, sulfates and sulfites, which lead to a release of H20, CO2 and SO2 and thus enable the heavy metal compounds to be “stripped”.

An advantageous embodiment of the invention is specified in claim 5. Heavy metals are present in the residues described in Table 1 in considerable amounts as high-boiling oxides or carbonates, which decompose to oxides during the thermal treatment. Through carbonaceous additives such as Activated carbon, graphite, anthracite or brown coal in proportions of 5-20% can reduce the heavy metal oxides. The environmentally relevant heavy metals have higher vapor pressures (Figure 2) in their reduced elemental form and are therefore increasingly evaporated.

An advantageous embodiment of the invention is specified in claim 6. By adding 5-20% of residues, which contain carbon in the form of activated carbon, graphite, anthracite, lignite, waste streams are combined and converted into usable glasses or sintered products. The heavy metal-containing residue allows the formation of a glass or sinter product with good immobilization of remaining heavy metal compounds, while the carbonaceous additive, which acts as a reducing agent, enables an optimized heavy metal depletion of the glass or sinter product.

An advantageous embodiment of the invention is specified in claim 7. The addition of 5-20% loaded activated carbon or lignite coke from flue gas cleaning is particularly favorable. The reducing aggregate leads to increased evaporation and thus depletion of the environmentally relevant heavy metals. At the same time, the disposal of the loaded activated carbon or the loaded lignite coke is solved, since the inerting temperatures destroy organic pollutants and bind or evaporate metallic pollutants.

An advantageous embodiment of the invention is specified in claim 8. Heavy metals are present in the residues described in Table 1 in considerable amounts in high-boiling, elemental form, as oxides or as carbonates, which decompose to oxides during thermal treatment. These compounds can react with chlorides as a salt or with chlorine or hydrogen chloride formed by decomposition to form heavy metal chlorides. The chlorides formed in the environmentally relevant heavy metals have significantly higher vapor pressures than the elemental or oxidic heavy metals (Figure 2). The chlorides are added as a salt (e.g. CaCl-2) or as covalently bound chlorine (e.g. PVC) in proportions of 1-30%.

An advantageous embodiment of the invention is specified in claim 9. By using residues that contain alkali or alkaline earth chlorides, waste streams are combined and transformed into usable glasses or sintered products. The heavy metal-containing residue allows the formation of a glass or sinter product with good immobilization of remaining heavy metal compounds, while the additive containing alkali or alkaline earth metal chloride enables optimized heavy metal depletion of the glass or sinter product.

An advantageous embodiment of the invention is specified in claim 10. It is particularly advantageous to add reaction salts from flue gas cleaning, or their mixtures with fly ash, such as are obtained in plants with quasi-dry flue gas cleaning. This alkali or alkaline earth chloride-containing additive leads to increased evaporation and thus depletion of the environmentally relevant heavy metals. At the same time, the disposal of the aggregate (reaction products of flue gas cleaning) is solved, since the heavy metals contained are depleted by evaporation and the remaining pollutants are incorporated into the glass or sinter matrix.

Embodiment

Addition of calcium chloride (conversion of heavy metal oxides to chlorides)

Heavy metal chlorides have significantly lower boiling temperatures than the corresponding oxides. It is therefore to be investigated whether the heavy metal oxides of the MVA filter dust can be converted into the corresponding heavy metal chlorides by adding chlorides and whether this results in increased heavy metal evaporation.

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Calcium chloride is an ideal additive for filter dust, since it occurs in conventional waste incineration plants for flue gas cleaning. Calcium chloride is mixed in such a way that the glasses from the experiments Cl and GascarbI have the same calcium contents and are therefore comparable. In the GascarbI experiment, calcium oxide was added to the filter dust.

Test conditions:

Temperature:

1300 ° C

TRY VERT:

30 g filter dust FSMVA

TRY GascarbI:

20 g filter dust FSMVA 3.00 g calcium oxide (53.6 mmol / 20 g filter dust = 2.7 mmol calcium / g filter dust)

TRY CL:

40 g filter dust FSMVA 11.78 g calcium chloride (110 mmol / 40 g filter dust = 2.7 mmol calcium / g filter dust) Calcium content of the sample 21.0%

Table 4:

Heavy metal concentrations in the glass when calcium chloride is added (in mg / g)

FSMVA + calcium chloride FSMVA + calcium oxide

copper

0.02 0.98

zinc

0.31 7.93

Lead n.a. * 0.008

Cadmium n.n. ** n.n. **

* <Limit of quantification of 5 ng / g ** <limit of quantification of 10 ng / g

An increase in the calcium chloride content leads to an increased evaporation of the heavy metals copper and zinc (Table 4 and Figures 3, 4 and 5). No statement can be made for lead and cadmium, since the control test (addition of calcium oxide) showed that the cadmium concentration was below the determination limit and the lead concentration was only just above the determination limit.

Claims (10)

Claims 1. Process for the thermal inertization of residues containing heavy metals, characterized in that additives are added which promote the evaporation of environmentally relevant heavy metals and thus the separation of these heavy metals from the matrix. 2. The method according to claim 1, characterized in that the additives contain hydrates, carbonates, sulfates, sulfite, which release gases during the thermal treatment and thus cause an effect of expelling heavy metal compounds. 3. The method according to claim 2, characterized in that the additives are residues. 4. The method according to claim 3, characterized in that the residues are reaction products of flue gas cleaning or aged waste incineration slags or fractions of these slags. 5. The method according to claim 1, characterized in that the additives contain carbon, which causes a reduction of the non-volatile heavy metal oxides and thus an increased evaporation of the reduced, elemental heavy metals, which generally have a lower vapor pressure. 6. The method according to claim 5, characterized in that the additives are residues. 7. The method according to claim 6, characterized in that the residues are loaded activated carbon or lignite, which were used in the flue gas cleaning for the separation of pollutants. 8. The method according to claim 1, characterized in that the additives contain chlorides which react with heavy metal compounds to form more volatile heavy metal chlorides. 9. The method according to claim 8, characterized in that the additives are residues containing alkali or alkaline earth chlorides. 10. The method according to claim 9, characterized in that the residues are reaction products of the flue gas cleaning. 7