DE3246324A1 - ENVIRONMENTALLY FRIENDLY FOUNDRY SAND ADDITIONAL FOR THIS AND USE OF THE ADDITIVES - Google Patents

Abstract

1. The use of a carbon product or of several such products, containing volatile components to a total of 0.5-20% by weight, wherein with naturally occurring products containing mineral materials the content in volatile components is calculated to the natural product without the mineral components.

Description

The present invention relates to novel foundry molding sand masses, the original objects, which are not only improved in terms of foundry technology bring, but in particular the demands from environmental protection looks at the workplace much better met. The invention also relates to the improved. "Ige η sch after, the additives causing the molding compounds and their use as Addition to foundry! Ormsanclen.

It is known, molding sands, which are used for the production of casting molds, are determined, carbonaceous additives in addition to the usual Add binders such as bentonite. An example of this is hard coal dust, which is added in particular to improve the surface quality of the castings obtained: ui (cf. DE-OS 1 952 235). The addition of coal dust takes place on the assumption that the Gießon through its gas formation unu The coating of the quartz grains with charcoal avoids burning of the sand on the casting and thus leaves a sheet and saubore Surface is generated. It was also found that the use of coal dust in the molding sand to compensate for the Sand expansion helps to avoid sand defects. Another suggestion is that the addition of a thermoplastic: plastic in a molded form as unsubstituted polymerized hydrocarbon,: - ,. h. the end Polymers of styrene, ethylene or propylons (cf. also DE-OS 1 952 357). That’s what they wanted so far

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Replace the carbon dusts used and the thermoplastic described Use plastics, especially in the ... that this causes glossy carbon in casting molds under the influence the casting temperature is formed, which the grains dpp Molding sand with a skin surrounds and the quartz grains of the Encased molding compound .. Another suggestion is that ' Adding resins to foundry sand, called hydrocarbon polymers are obtained in the form of so-called petroleum resins in petroleum distillation (cf. DE-OS 2 064 700). This solution, too, c / ehc. assume that under the conditions of the casting heat a partial Volatilization of the additives takes place and subsequently Bright carbon is deposited from the gas phase, the clann the separation between metal and molding material. However, the goals achieved are still highly unsatisfactory, especially from the point of view of environmental protection in the workplace and in general. The following table 1 lists the products used so far and the standardized, internationally accepted measuring methods, i.e. According to DIN 5172, volatile components measured at the casting heat. The following table 2 shows the various Products between 400 and 700 ° C in an oxidizing or reducing atmosphere volatile constituents.

BATH ORIGINAL

TAJ3ELLE 1

description

Delivery Color Bulk density C content Ash form

g / cm ⁵

Pyro

coal

■ Clever crucible material made from sulfur
Inventory coke of the gas parts phase "
Χ waf Jo waf 5s wf

Pyrokohlenstot'f from the
Gas phase and total Ci stood as return loss

% waf %
- more effective

Test,
lines powder black DIN
5346a “70 DIN
51721 75 DIN
51719 10, DIIJ
51720 DIN
51720 8-10 DIN
51724 73-75 ' 25-27 Hard coal
lenstäube powder black 0.60-0 , 60 70 - 78 4 - 7th 0 30 - 37 63-70 14-18 0.7-1.5 72-74 26-23 syntheti
shear Koh
oil dust powder black 0.50 - 0 , 55 73 - 92 4 - 1 40-44- 56-60 25-35 0.7 - 1.0 78-80 20-22 Foundry-
bad luck powder black
Brown 0.45 - 0 , 55 88 - 90 0 - 1 45 - 55 45 - 55 22-33 0.5-0.8 60 - 63 37-40 bitumen powder yellow
Brown 0.45 - 0 , 50 86 - 90 0 - 1 60-70 30-40 35-45 0.9-3.8 69-71 29-31 Resins,
Coal chemistry powder yellow 0.45 - 0 , 50 86 - 90 0 - 1 65-75 25 - 35 45 - 55 0.2-0.4 59-61 39-41 Resins,
Petro-Chemla fluid Brown
until
black 0.45 - 0 .05 86 - 91 0 - O ₈ 90-95 5-15 40-55 0.1-0.4 50-57 43-50 '' oils powder
Pearls
Fibers colorless
or
White 0.8 - 1 , 70 85 - 95 0 - 1. 5 90-98 2-10 10-60 0.5-3.5 25 - 62 ' 38-75 Plastics 0.40-0 35 - 0 - 5 85-96 2-15 0 - 0.2

TABEL

Release of volatile components

in reduced and oxide. the atmosphere

of products from table

at different temperatures in %

Description! Pitch EP temperature C atmosphere oxide.

Bitumen coal dust petro resin coal resin atmosphere atmosphere atmosphere atmosphere reduce. oxide. reduced oxide. reduced oxide. reduced oxide. reduced

18.77 3.94 9.52 4.74 52.51 4.48 51.72 52.70 26.56 18.07 49.00 25.04 69.45 28.71 96.33 20.6 97.10 70.52 87.59 47.75 94.88 39.68 79.33 36.74 96.64 29.04 100.00 82.95 100.00 59.90 96.19 41.50 79.51 37.11 96.74 32.34 100.00 83.20 100.00 63.90.

The samples were kept at the respective temperature for 1 hour.

CO N)

CD CO N)

According to all previous methods, the effect of the carbonaceous additives previously used on the under Conditions of casting heat volatilization of Hydrocarbon compounds are based on what after Formation of a reducing atmosphere that separates so-called lustrous carbon above 650 ° C. The educated Bright carbon is said to be the separation between liquid metal and casting molding compound by removing the skins of the casting mold sand enveloped.

The following are the decomposition products and their composition a gas coal and a hydrocarbon resin listed, which during the thermal iiiasetzuna in reducing atmosphere.

A) Application of gas, benzene and tar

From a gas coal with 3 3 %, insane η components escape

100 kg coal = 43.8 N m ³ gas

3.6 kg of tar
1.15 kg of benzene

Average analvse of the gas?

co ₂ 1.8% The heavy ones Hydrocarbons ^C n ^H m 2.3% sit down together from: O ₂ 0.2% ^C 2 ^H 6 0.82% CO 4.7% ^C 2 ^H 4 1.21 % H ₂ 64.6 % ^C 3 ^H 3 0.07 % CH ₄ 24.5% ^C 3 ^H 6 0.20% ^N 2 1.3% C <-H _r 0.6%

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324632A

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B) Analysis of the volatile components of tar: in the boiling range of

0 - 170 ° C benzene - toluene - xylene - phenol - pyridine 170 - 230 ° C naphthalene - phenol - cresol - bases 230 - 270 ° C creosate - naphthalene - neutral oils 270 - 350 ° C anthracene - phenantrene - korbazole

approx. 0.5% benzopyrene-3,4 pitch: free carbon - phenantrene - chrysene

about 1.0% benzopyrene-3,4

Boiling point of 3.4 benzopyrene linqt. at 495.5 ^ C The boiling point of 1,2-benzopyrene is 492.9 ° C

C) Thermal decomposition of a hydrocarbon resin at 1,000 ° C, An;
Components

1,000 C, analysis of the incurred, en fugitive / s

Hydrocarbons, low 0.3 % Cyclopentadiene 0.2% benzene 1.5% toluene 2.7 % Ethylbenzene + m-, o-, p-xylene 2.2% Styrene 7.3 % Cumene 0.2% Allyl benzene 0.1 t Ethyl toluene 0.4 I. cv -Methylstyrene 1, 4 % o-, m-, p-vinyltoluene 18.0 I. ß-methyl styrene 0.3 % In the 19.4 % Dimethylstyr oil 8.4 ° j Methylindene 1 H , 5?. naphthalene 19.1 Ϊ.

BAD ORlGaNAL

As can be seen, when using the previously known additives, volatile constituents are given off under Environmental considerations contain extremely harmful components, such as those used today as carcinogenic agents In other technical areas, e.g. aromatics benzene, toluene and xylene that are no longer permitted as solvents. (See R.W. Schiraberg et al., Burden of Eisengieiiereiarheitern through mutagenic polycyclic aromatic hydrocarbons, Dust cleanliness. LuIt Vol. 41 (1981) p. 421 424). Also contain the gases released during the pouring process in the workplace untraobably high levels of carbon monoxide.

Contrary to the previous assumption of the prerequisite for the effectiveness of the previously used carbonaceous additives in foundry molding sands, the original additives represent carbon products with a volatile content of 0.5 to 20 % , preferably 0.5 to 10%, based on the amount of the carbon products freed from any mineral components that may be present in the natural product. They are advantageously present in the additives with a particle size of less than 1 mm, preferably less than 0.15 ram. In particular, the so-called crystalline carbon products, which generally contain less than 1> volatile constituents, are suitable as such products. Since it is on these products generally around is relatively expensive products, organic Kohlcns can been to s f. Products trains mixed, the upper hall in the formed during the Gicßvorganaes reducing atmosphere) of 650 ° C can itself form crystalline carbon and a proportion of volatile constituents from 1 to 20?>, preferably between. 5 and 10 % , provided that the carbon product according to the invention has volatile constituents only within the limits specified above and the maximum volatile constituent content of 20%, preferably

BAD ORIGJNAL

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10 %, is not exceeded.

Examples of inventions. ^ | ^

Carbon products and for admixable ^ i-'ülilQnst-Off-. Products are listed in Table 3, while the components that occur when pre-cracking in the sand of the foundry molds are volatile are listed in Table A.

The expression "natural graphite" is hiorboi r> o to understand that the naturally occurring iTraPhxtRiinpr ^ lipn iro allnßix considerable menaon of mineral 1 osl ondrox] cn (^ iiU which before their usability in nckann l'on 1``It) I ciLiuns or chemical Hehanülunqsverfahr / ^ n hif ^s rvÄ ^; ^ 'Asftf ^ wf ' ^ must be used as additives to Ciioßerei.t.orr.isanilc. ! xT.i are. The so qereiniate not .in this roinon 'l'Orni 1' * c ^J or naturally occurring product v; ill iiblichorw ^ iso as. "; · Αί" -rcraohii. - .; ■ ". -.-.'-. ■, - '■ ·; -," - /' ■■: ■

ORIGINAL BATHROOM

description

TABLE 3

Delivery Color Bulk density C content form g / cm %

Volatile residue ash Components carbon % wf ίό waf ü waf

carbon from the gas phase

act pan ·, he total Cabbage enstoi'f: Loss of gas Pyrükuhlenstoff % and sulfur Residual carbon ' % Wf % waf

Test dir
lines powder black,
glittering DIN 53468 DIN 51721 , θ DIN
51719 DIN 51720 Max.
0.5 DIN 51720 Max.
0.1 DlN
51724 99.6-99.8 Max.
0, · '?. * 'V • powder black,
glittering ,8th Max.
0.5 Max.
0.1 99.6-99.8 nax. ■ f.'aturpraphit
finer grain
more crystalline
carbon powder black,
glittering 0.6 - 0.7 99.6 - 99 .8th Max.
0.2 Max.
0.5 99.5 - 99.7 Max.
0.1 Max.
0.1 99.6-99.8 cax,
0, ' _? • r.atur ^ raphit
coarse-grained
more crystalline
carbon powder black 0.6 - 0.7 99.6 - 99 ,8th Max.
0.2 Max.
0.5 99.5 - 99.7 Max.
0.1 Max.
0.1 99.6-99.8 May.
0, 'i ". 11th Electrography
more crystalline
carbon powder black
glittering 0.6 - 0.7 99.6 - 99 ,8th Max.
0.2 Max.
0.5 99.5 - 99.7 Max.
0.1 Max.
0.1 99.6-99.8 Max. ·
0.4. D ORIGfr Ru ύ
axorphic
carbon powder black 0.1 - 0.5 99.6 - 99 ,8th Max.
0.2 Max.
0.5 99.5 - 99.7 Max.
0.1 Max.
0.1 99.6-99.8 Max. .
0.4 .. > Pyrographite powder black 0.5 - 0.6 99.6 - 99 Max.
0.2 6-10 99.5 - 99.7 1 - 2 Max.
0.1 91.5-95.5 4.5 - Pyro-
carbon powder black 0.3 - 0.4 99.6 - 99 Max.
0.2 14-16 99.5 - 99.7 4-6 Max.
0.1 89.0 to 91.0 9 - anthracite
money 0.5 - 0.6 94 - 96 5-7 90 - 94 Max.
0.2-1.1 Charcoal 0.5 - 0.6 89 - 91 5-7. 84 - 86 Max.
0.8-1.1

co VO ro I. CD CO hO -fc-

TABEL

Release of volatile components in reduced. and oxide. Atmosphere of carbon products from Table 3 at different temperatures in ^!

Natural graphite Natural graphite Electrographite soot fine-grain coarse-grain fine-grain amorphous crystalline crystalline crystalline carbon-carbon carbon carbon

Pyrogra Pyro anthracite Skinny phit coal money money material

Atmosphere atmosphere atmosphere oxide, reduced. oxide, reduced oxide, reduced Atmosphere Atmosphere Atmosphere Atmosphere Atmosphere Reduced Oxide Reduced Oxide Reduced Oxide Reduced Oxide Reduced Oxide Reduced Oxide

tempera ⁰ C 0 , 61 1 ,1 0 , 65 1 , 2 0 ' 5 1 , 5 door ⁰ C 1 , 42 2 ,1 1 , 3 2 , 3 1, 1 2 , 6 400 ⁰ C 3 , 64 5 , 3 3 , 5 5 , 6 3, 3 7th , 2 500 ⁰ C 15th , 7 5 , 4 14th ,8th 5 , 9 12, 7th 7th , 5 600 700

2.3 1.8 0.63 1.2 2.2 1.6 5.3 1.6 26.1 3.2 £

3.6 2.8 1.5 2.0 3.5 2.5 81.4 3.5 89.6 9.9 '

7.2 7.9 3.7 5.4 7.1 7.3 90.5 7.7 92.0 14 ^: 7

19.4 11.1 16.0 5.45 19.2 9.8 90.5 7.7 92.0 15, / S ₁₁

Hicraus can be seen that the thermal load during the casting process in the case of the molding sands according to the invention, the additives according to the invention (carbon carriers) and their use as additives to foundry molding sands, the gasmnnqe is clearly gorinqor. A11 go ine in it can be observed that the flashes of fire when pouring the hot liquid metal into the casting molds, as is usual with the use of the previously known additives, e.g. Molding sand? .Η with the erfindunasffer; u'.ißen carbon carriers as additives no longer occurs. The abomonqon to "carbon träoern to Recroneriorung the molding sand can to un 25 to 50 ° can be reduced, nit ^ilf ■ 'result da'ß environmental impact in Her Gießeroi to a minimum reduced is. Numerous Gasuntersuchun ^ s have confirmed that When using carbon carriers r.iii a content of volatile constituents of B to 10% wa. ", in addition to reducing the hydrocarbon compounds, the content of carbon monoxide in the AtIaOSt- ¹ I) urine on the pouring line and unpacking station to approx. 20 ppm heralxfesetzt v-irc .. When using Kohlenstoffträgcrη with a content of volatile constituents from 4 0 to 45 Z waf steigt.der CO - 'vort there on BO to 100 ppm, whereby the o / vK-Grcnzwert of 50 ppm significantly exceeded. will. lio. In view of the previous teachings in the prior art, it is surprising that, despite the greatly reduced levels of volatile constituents contained in the additives, aerade dir ;. The surface of the casting is free of defects, such as ribbon ribs and the like. The separation between the molding sand and the casting is flawless, and with a greatly reduced amount of additive to the molding sand.

The combination of crystalline carbon products with Anthracite or lean coals as admixture carbon product has been found to be particularly beneficial. Anthracite- and lean coals already react during the casting process

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32Λ632Α

at low temperatures (150 to 400 ° C) with "the im Pormhohlraum present atmospheric oxygen, and thus create very quickly a reducing atmosphere, which is a prerequisite for the crystalline carbon products now also suffer very little losses during or after the casting process.

The additives according to the invention form foundry sand masses an ideal protective layer between the flussiaen Ho-LaIl and the molding sand mass, with which Reaktiobeb between the molten metal and the molding sand has been prevented.

Another advantage of using the invention-sgerfiüu Additives (carbon carriers) are the low water requirements of the molding sand according to the invention thus formed during the preparation process, including dio erf induiiunoouäß used additives (carbon carriers) compared to "the conventional Carbon compounds have a substantially acringero Have surface.

The flow and sealing seal is designed with external components that meet the requirements Additions of mixed molding sand is also improved, since the additives used according to the invention (carbon sluggish) significantly reduces the frictional resistance of the clay-coated quartz grains.

In addition to the technical foundry advantages listed, the molding sand according to the invention and the erfinuunusaeiivir.on addition, the environmental pollution in the foundry is considerably reduced a proportion of volatile components at potting temperatures around 3G Isis 4 0 Z are used, ie approx. 20,000 t / year Kolileuwansers tol compounds are removed into the atmosphere. 20,000 t / year of hydrocarbon compounds, based on

BATH ORIGiMAL

- / Pf- share of volatile components of approx. 40 %, 10,612,000 m ³ gas, 85,400 kg tar and 272,000 kg benzene.

Trial s called The following sand mixtures were produced for the trials:

Sand mixture 160 kg of sand

14.4 kg mixture

30 % carbon, inert 70% bentonite 4.3 kg H ₂ O

8 mixtures were made:

Mixtures 1-5: carbon carrier = natural graphite

with different surfaces

Mixture 6: carbon carrier = pure bitumin Mixture 7: carbon carrier = mixture of

highly volatile coal + bitumen Mixture 8: Carbon trainer - mix of

low volatility coal + bitumen

The sand mixtures have the following sand values: Mixture H ₉ = compressive strength compressibility test body ^{weight 1}

55 155

60 152

55 149

63 152

61.5. 14 8.5

63.0 150.0

61.0 149.0

6 2.0 148.0

A special model was selected for all experiments so that verals are possible.

1 2.9 600 2 2.7 630 3 2.6 490 4th 2.9 800 5 2.9 610 6th 2.7 700 7th 2.8 660 8th 3.0 610

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32A6324

The sands were used as model sand without sieving.

When all boxes were poured, it was found that samples b, 7 and 8 developed more flames.

sample Gas analysis Pouring off Sample 3 Vol. of tearing away Vol.% Sampling 0.12 Casting line before Unpacking station during unpacking 0.23 1 21, 0 Casting line during 1 sample 2 2 0, f > 2 33 % Vol.% 118 3 0.02 0.10 0.0 2 0.00 21.0 0.02 78.85 62 78.81 co ₂ 0.00 0.02 0.00 ° 2 0.00 0.00 0.02 Cu 0.00 78.83 0.00 ^H 2 0.00 0.00 0.00 0.02 0.02 0.02 ^N 2 0.00 0.00 0.00 ^C 2 ^H 6 0.00 0.00 0.00 C ₂ H ₄ η. η 0.00 n. n. C ₂ H ₂ 99.99 0.00 99.98 ^C 3 ^H 8 0.00 ^C 3 ^H 6 η. η. ^C 4 ^H 1O 99.98 C ₄ H ₈ ^C 6 ^H 6

BATH ORIGINAL

Unpacking behavior

The castings or samples were unpacked under the same conditions. Samples 1-8 could be evaluated as follows will:

Sample 1 practically no odor formation Sample 2 Sample 3 Sample 4 "" ".

Sample 5 Sample 6 very strong odor generation. Sample 7 strong odor generation Sample 8

Castings after steel

First, the general cast surfaces were assessed. Samples 1-8 clean surfaces

The casting noiqt to vein formation and it could it can be found that the veins are stony, the higher the volatile constituents in the carbon, the more murky it is are.

Samples 1-5 show no veins, but samples 6 and 7 strong tendency of leaf ribs and in the case of sample δ only weak beginnings of leaf ribs were recorded.

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Claims (9)

.: /; -:: -r .- 32Α632Α claims ,: 1. Additive for molding compounds in casting molds using natural and / or synthetic molding sands with customary binders, characterized in that the additive consists of a carbon product or one ('<~ · - a mixture of several such products, where <' as Additional product flüchtino component ^ total of 0.5 - 20 fie \ 7. " 2. Additive according to claim 1, characterized in that the additional product is present in a particle size of less than 1 mm. 3. Additive according to claim 1 or 2, characterized aekennzeiclvnut, that the carbon product is a crystalline carbon is a material product. 4. Addition according to claim. 1 or 2, thereby indicated, that the crystalline i'ohlenstni.'f.product; ms kolilenvannorstoffhaltirron Verbim.unaen in reducing At'iosi / rvir ^ Ιχ, 'ΐ a Toni!> Ernfur between 050 and 1000 C b ^ rciontollo wurdo. 5. Addition according to claim 3 or / 3, characterized in cre that the crystalline carbon product is one of minerals present in the graphite mineral Katurc / raohit is exempt from components. 6. Addition according to .Anspruch 5, characterized in that the Natural graphite oine surface area from 0.4 to 15 in "has. 7. Addition according to claims 3 bin Γι, 'i characterized that the crystalline coal ns toi II -rudukt from syntlietisctien Granhiteiv is made. BATH ORIGINAL 8. Foundry molding sand, consisting of a natural and / or synthetic molding sand, a common binder and a carbonaceous additive, thereby aokennzp.ichnet, that the carbon-containing additive is an additive according to: or more of claims 1 to 7 is. 9. Use of carbon products or mixtures of several carbon products of an odor more of claims 1 to 7 as an additive for molding compositions in natural or synthetic using Forms Toggle according ^to: · nit usual binders produced fJießformen. BATH ORIGINAL