JPS5919522A - Treatment of waste gas during production of casting mold - Google Patents

Abstract

PURPOSE:To convert org. amine to a harmless solidified substance without requiring a complicated apparatus and complicated manipulation, by a method wherein a strong acid salt is added to a weak acid contg. org. amine in a waste gas generated during the production of a casting mold and absorbed in the weak acid and the resulting mixture is neutralized with a weakly basic substance and solidified by a hydraulic substance. CONSTITUTION:A strong acid salt such as iron sulfate is added to a waste liquid obtained by absorbing an org. amine-containing waste gas generated during the production of a casting mold with phosphoric acid to form insoluble amine sulfate. In the next step, a weakly basic substance such as CaCO3 or Ca(OH)2 is added to neutralize the treated waste liquid. After neutralization, a hydraulic substance such as cement is added to the neutralized liquid to form a slurry which is, in turn, discharged and solidified.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention enables the production of a weak acid that has absorbed the waste gas of toxic organic amines used in manufacturing molds without requiring complicated equipment or equipment or complicated operations. The present invention relates to a method of converting it into a harmless solidified substance by a safe and harmless method.

There are various manufacturing methods for conventional & 15 molds, but recently a one-pass gas mold curing method has been developed as a mold manufacturing method that is compatible with energy saving, labor saving, and high speed. There is a cold box method that can be obtained.

This method involves coating sand grains with resin components polyisocyanate and polyol as binders and filling them into a model, and then blowing an organic amine as a catalyst into the mold together with a carrier gas. This is a method for manufacturing molds by passing urethane (fat) through the sand grains, which causes the sand grains to solidify together.

In this method, the organic amine-containing waste gas that passed through mold C3 and the clean gas blown into the tank to expel the organic amines remaining in the mold space are discharged outside the mold as waste gases containing organic amines. Ru. These discharged gas #j
It is washed with an acidic liquid and released into the atmosphere as a clean gas that absorbs organic amines.

The weakly acidic liquid that has absorbed the organic amine is either entrusted to a vegetable distributor for treatment, or it is diluted with caustic soda (1) and then introduced into a wastewater treatment device for treatment. However, since the organic amine odor re-occurs during the neutralization process, the absorption and cleaning process is performed again.

It is necessary to carry out re-adsorption work using activated carbon, or to perform roasting, etc.

The present invention uses these devices, does not require any madder work, uses mainly phosphoric acid as a weak acid, and has a strong acid salt ratio of 1: (1
1ij acid, hydrochloric acid 1°, salt with organic amine becomes solid, and Fe, Ca, A1. Mg and the like may be used, but it is preferable that the salt with phosphoric acid forms a water-immobilized II product.

Weakly basic substances include carbonates, silicates, hydroxides, and oxides such as Fe0a, A1. F such as Mg may be used, but alkali metals are not preferred because their salts with phosphoric acid are water-soluble.

After neutralization, use hydraulic materials, such as cement, mortar, concrete, paste (
iRere is also fine.

Actual tIM Example 1 Waste liquid (PI(3),
Collected 100ca.

Iron sulfate 20 while stirring well! When added, iron sulfate was not completely dissolved, but the PHj of vaginal fluid changed, indicating that amine sulfate was generated.

Next, when Cal/Yu carbonate was added, the neutralization reaction was accelerated while generating carbon dioxide gas, but no organic amine odor was observed.

After the generation of carbon dioxide gas stopped, the PII of the slurry was checked and showed a neutral pH of 7. After confirming that there is no pH change for more than 10 minutes, cement is added and a stiff slurry (P
It was discharged as H10) and solidified.

After one week, the solidified nuclear material was crushed and added to 100% CO of distilled water.
0! In addition, the pH of the vaginal fluid after boiling for 2 hours was 10, and the state after standing was n'Nσ, and no odor was observed.

(Reaction) Waste liquid composition (PII3) Product 1 (
PH1)H 0 Product 2 (PH7) Product 3 (PHI
OJH■0 2.1) Waste liquid (pH 3) + which absorbed organic amine in 7 acids
Collect ooCc.

When 20/20% was added without stirring well, the stone 1f was not completely dissolved and the pH of the vaginal fluid changed to 1, indicating that amine sulfate was produced.

Next, when cement, which is a collection of weakly basic substances, is gradually added, the pH gradually rises by 2' with the generation of carbon dioxide gas. Cement is weakly basic 111! Since it is both a lubricant and a hydraulic substance, it was added continuously without making sure of the pH change, and after mixing until it became a paste, it was discharged and solidified. No odor of organic amine could be detected during this neutralization and cross-talk.

Similar to Example V1, the solidified product was crushed after one week, 30 pieces of the crushed product was added to 100 CO of distilled water, and after boiling for 2 hours, the pH and odor of the boiled liquid were determined.

I checked the state after standing still, but the result was the same as in Example 1.
I got it.

(Reaction) Waste liquid composition (PH3) Generation' threshold ICPI
', +)t0 Product 2 (PH10) Product 3 (PH1
0) Phosphate + hydraulic substance & IJ acid absorbing organic amine waste liquid (pu3)
Collect 1ooCa and add 1" of iron sulfate while stirring well.
When 5/ is added, iron sulfate is not completely dissolved and the pHi
, indicating the formation of amine sulfate.

Next, add slaked lime gradually and after checking the pH of 7, add slaked lime to 50! Immediately after adding and homogenizing the mixture, cement was added and the mixture was discharged and solidified in the form of a soft slurry (PHlo).

No amine odor was observed during this neutralization and hydraulic substance formulation.

After one week, the solidified product was crushed in the same manner as in Examples 1 and 2 (it was softer and powderier than the former two), and distilled water was added to it.
After taking 20 grams of the crushed material and boiling it for 2 hours, the PH1 odor of the hindlimb boiling liquid was checked.
0. No odor could be detected, and only 17 vaginal fluids were found after standing.

(Reaction) Waste liquid composition (PH, 5) Product 1 (P
Hj )z 0 Product 2 (PH'7) Generation! l'lJ
5 (PH10)tO Product 4 (PHIO) As described above, the present invention does not require complicated equipment or devices and can be easily converted into a harmless solidified product by a safe and harmless method without requiring complicated operations. It has many industrial effects, such as being able to improve productivity by providing effective pressure in terms of environmental hygiene.

Patent applicant Incorporated association; 1 construction technology 1 and T46 association 1
given name

Claims (1)

[Claims] As detailed in the main text, a salt of a strong acid is added to a weak acid that has absorbed organic amine-containing waste gas generated during the production of a mold, the organic amine is stabilized as a strong acid salt, and then a weak basic substance is added. % gas treatment method during mold manufacturing, characterized by adding a hydraulic substance to the mixture and solidifying it after softening.