CS267901B1 - A way of neutralizing waste mineral acids - Google Patents

Abstract

It solves the neutralization of waste mineral acids with alkalis. Alkaline wastewater is used for pre-neutralization, and after pre-neutralization, part of the impurities are separated by sedimentation. Then, the waste mineral acids are further neutralized with calcium hydroxide, preferably in the presence of an electrolyte. The precipitated impurities are separated by sedimentation.

Description

The invention solves the neutralization of mineral acids which are contaminated with organic and inorganic substances.

Mineral acids, especially sulfuric acid and hydrochloric acid, are very often used in industry. After use, dilute mineral acids are often formed, which are contaminated with organic or inorganic substances. Prior to discharge into watercourses, it is necessary to neutralize these waste mineral acids, which is most often done with calcium hydroxide.

In the chemical industry, alkaline wastewater is often generated, which consists mainly of contaminated alkali hydroxides. Before being discharged into watercourses, alkaline effluents must be neutralized ', which is most often done with mineral acids. A certain disadvantage of neutralizing acidic waters is that calcium hydroxide is used and mineral acids are used to neutralize pupils and alkaline lines, thus increasing the cost of discharging wastewater.

The above-mentioned shortcomings are alleviated by the method of neutralization of mineral waste acids, the essence of which consists in the fact that mineral acids contaminated with organic substances, especially sulfuric acid, sulfuric acid, nitrogenous, chi order, hydrogen, inorganic substances, especially sulphates and chlorides, sodium cations, calcium cations. , magnesium, iron, aluminum, zinc, the mineral acids being neutralized by alkalis. Waste sodium hydroxide containing cellulose xanthate, sodium sulphide, sodium sulphate, sodium thicarbonate, sodium sulphite, sodium 3-methyl-4-nitrophenolate and sodium salts of 3-methylphenol and its nitro-, nitroso- and sulphoderates is used for the pre-neutralization of mineral acids. ivátov. After pre-neutralization, impurities such as cellulose, sulfur, zinc sulfide, 3-methyl-1-4-nitrophenol precipitate, which are preferably separated from the reaction mixture by sedimentation. The pre-neutralized reaction mixture is done with a calcium hydroxide suspension, preferably in the presence of an electrolyte, and precipitated impurities such as iron, magnesium, aluminum and zinc hydroxides are separated from the reaction mixture by sedimentation.

An advantage according to the invention is that waste alkaline waters are used for the pre-neutralization of the waste mineral acids. The mutual reaction of the waste mineral acids and the waste alkaline waters produces less polluted waste waters than in the neutralization of the waste mineral acids with calcium hydroxide and the neutralization of the waste alkali metals with monobasic acids. According to the process of the invention, due to the precipitation and separation of part of the impurities from the reaction mixture in the form of sludge, less impurities enter the aqueous stream than if the waste mineral acids and waste alkaline water were discharged into the aqueous stream separately. The pre-neutralization of the waste mineral acids must be carried out in such a way that the hydrogen sulfide and sulfur dioxide formed do not escape from the reaction mixture into the air, but remain in the reaction mixture or react to a compound which can be separated from the reaction mixture, as in the case of the reaction of hydrogen sulphide with zinc cations to zinc sulphide. The discharge of neutralized waste lines will eliminate the fees that must be paid to the flow manager for the discharge of acidic or alkaline waste lines.

Example 1 ’

The waste mineral acid had the following composition:

Ch SK (Cr, 2 h) 840 mgO? pH value 1.7 so / - 1,760 mg / l C1 1,125 mg / l Mg ²⁺ 94 mg / l

CS 267 901 Bl

Fe ³ *

Al ^{3 +} mg / 1 mg / 1 mg / 1

The waste alkaline water from the crystallization of sodium 3-methyl-4-nitrophenolate mixed with the waste water from the production of viscose silk had the following composition:

sodium salt of J-methyl-4-nitrophenol 5.6 g / l after all, 3-methylphenol derivatives 2.6 g / l NaCl 45 g / l cellulose xanthate 0.2 g / l Na ₂ S0 ₄ 6.5 g / l Na 2 S, Na ₂ Sx as Na ₂ S 2.7 g / l On ₂ SOj 0.2 g / l Na ₂ S ₂ 0j 0.01 g / l NaOH 19 g / l

Kil of waste mineral acid was added 100 ml of waste alkaline water. The precipitated impurities were separated from the reaction mixture by sedimentation. The reaction mixture was then neutralized with 37% by weight of calcium hydroxide suspension to pH 7.5. Donutralization was performed in the presence of 0.01 g of polyelectrolyte. The precipitated impurities were separated by sedimentation. Example 2

The procedure of Example 1 was followed, except that neutral separation was not performed in the presence of the polyelectrolyte. After completion, the precipitated impurities were separated by sedimentation. The pH of the solution was 6.3.

The invention can be used for the neutralization of waste mineral acids if alkaline wastewater is generated in the plant.

Claims (1)

2 EN 267 901 01 Ee 3 * 14 mg / 126 my / 112 mg / 1 Waste alkaline water from crystals of 3-methyl-4-nitrophenolate sodium zmoSanas wastewater from viscose silk production had the following composition: 3-methyl-4-nitrophenol sodium salt 5.6 g in addition, 3-methylphenol derivatives 2.6 g / l NaCl 45 g / l cellulose xanthate 0.2 g / i Na 2 SO 4 6.5 g / i Na 2 S, Na 2 S 2 as Na 2 S 2.7 g / i Na 2 SO 2 0.2 Na 2 S 2 O 3 (0.01 g) and NaOH (19 g) and 1 K waste mineral acid was added with 100 ml of waste alkaline water. The precipitated impurities were separated from the reaction mixture by sedimentation. Then, the reaction mixture was neutralized with 37 wt. calcium hydroxide suspension to pH 7.5. Ooneutralization was performed in the presence of 0.01 g polyelectrolyte. Precipitated impurities were separated by sedimentation. Example 2 Example 1 was followed except that neutralization did not occur in the presence of polyelectrolyte. After centrifugation, the precipitated impurities were separated by sedimentation. The pH of the solution was 6.3. The invention can be used to neutralize waste mineral acids if alkaline effluents are formed in the plant. DESCRIPTION OF THE INVENTION The method of neutralizing waste mineral acids contaminated with organic substances, in particular with oxygen, sulfur, nitrogen and chlorine derivatives of hydrocarbons, inorganic substances, in particular sulphates, sodium cations, calcium, magnesium, iron, aluminum, zinc, and alkali, mineral acids are non-neutralized with sodium hydroxide containing cellulose xanthate, sodium sulphide and polysulphide, sodium sulphate, sodium thiosulphate, sodium sulphite, sodium 3-methyl-4-nitrophenolate and sodium 3-methylphenol and its sodium salts. nitro-, nitroso-, and sulfoderivatives, wherein after pre-neutralization, preferably precipitated impurities such as cellulose, sulfur, zinc sulfide, 3-methyl-4-nitrophenol are separated by sedimentation from the reaction mixture which has been rendered 9 with calcium hydroxide. preferably the presence of polyelectrolyte to a pH of 5.5 to 8.5 and precipitated impurities such as h The ferric, magnesium, aluminum and zinc hydroxides are separated from the reaction mixture by sedimentation.