CS267903B1 - The way of neutralizing mineral contaminated acids - Google Patents

Abstract

The neutralization of contaminated mineral acids with alkalis is addressed. Mineral acids are neutralized with contaminated sodium hydroxide, precipitated impurities are separated by sedimentation, and the reaction mixture is further neutralized with calcium hydroxide in the presence of a polyelectrolyte, and precipitated impurities are separated by sedimentation.

Description

EN 267 903 Q1 1

The invention solves the process of neutralizing mineral acids produced in the chemical industry. In the vel'ml industry, contaminated acids often fall off, causing problems with their disposal. When discharging into watercourses, the flow manager has to pay zaacidity fees. Most often, the acids are neutralized prior to discharging into aqueous streams, especially with calcium hydroxide.

The aforementioned drawbacks are alleviated by the method of neutralizing mineral contaminated acids, the principle being that the mineral acids are neutralized with alkali. Mineral acids are contaminated with organic substances, especially with acidic, sulfuric, nitrogenous, chlorinated hydrocarbons and inorganic substances, the most disulphurized, chloride and cations of sodium, calcium, magnesium, iron, aluminum, zinc. Mineral acids are pretreated with sodium hydroxide containing xanthogenate cellulose, sodium sulfide, sodium polysulfide, sodium sulfate, sodium thiosulfate, sodium sulfite.

After pre-neutralization, the precipitated impurities such as cellulose, sulfur, zinc sulfide are preferably separated from the reaction mixture by sedimentation. The reaction mixture is then carried out with calcium hydroxide to a pH of 5.5 to 0.5, preferably in the presence of a polyelectrolyte. The precipitated impurities, in particular ferric, magnesium, aluminum and zinc hydroxides, are separated from the reaction mixture by sedimentation. An advantage of the invention is that the mineral contaminated acids are pre-neutralized by the waste. alkaline liquors containing cellulose xanthate, sodium sulfide, sodium sulfide and other impurities. In the reaction, impurities such as cellulose, zinc sulfide, sulfur precipitate, which are separated from the reaction mixture by sedimentation in the form of sludge. After being carried out with calcium hydroxide, zinc hydroxides, iron (III), aluminum (II), and magnesium hydroxides are used as sludge. After neutralization of the mineral acids and the contaminated sodium hydroxide, less pollutants are obtained when discharged into the watercourse, if they are discharged separately or discharged after separate neutralization. Zinc, which is toxic to surface streams, is virtually removed from the mineral acids. The discharge of neutralized wastewater removes the charges for discharging the acidic or alkaline waters into the watercourse that are required to pay the watercourse manager. Example 1

Contaminated mineral acid has the following composition:

COD GCr, 2 h) 790 mg 0 pH value 1.9 2 SO / 1 650 mg / 1 Cl "1 125 mg / 1 Mg2 * 101 mg / 1 Pe3 + 18 mg / l AI3 * 14 mg / 1 Zn2 * 8 mg / l

Contaminated sodium hydroxide has the following composition:

NaOH cellulose xanthate

Na 2 SO 4

Na 2 S, ha 2 S x as Na 2 S

Na2S0j

Na 2 S 2 O 3 21 9/1 0.2 9/1 2.2 g / i 1.9 g / i 0.2 g / i 0.039 9/1

Claims (1)

The waste mineral acid was added with 100 ml of waste sodium hydroxide. The precipitated impurities were sedimented. Then the reaction mixture was neutralized with 5 wt. calcium hydroxide suspension. Neutralization was performed in the presence of 0.01 g polyelectrolyte. The precipitated impurities were separated from the reaction mixture by sedimentation. PH pH 7.0. Example 2 Example 1 was followed except that the neutralization was carried out in the absence of polyelectrolyte. After sedimentation, the pH was 6.2. The invention can be used to neutralize mineral acids before they are released into water streams. SUMMARY OF THE INVENTION The method of neutralizing mineral contaminated acids containing acidic, sulfurous and chlorinated hydrocarbons, inorganic substances, especially sulphates, chlorides, sodium cations, calcium, magnesium, iron, aluminum, zinc, with alkali characterized by the fact that mineral acids are pre-neutralized with sodium hydroxide containing, as impurities, cellulose xanthate, sodium sulphide, sodium polysulphide, sodium sulphate, sodium thiosulphate and sodium sulphite, wherein after pre-neutralization, impurities such as cellulose, sulfur, zinc sulphide are preferably separated by sedimentation from the reaction mixture which is rendered neutralized with hydroxide calcium to a pH of 5.5 to 8.5, preferably in the presence of a poly-electrolyte, and precipitated impurities such as ferric, magnesium, aluminum and zinc hydroxides are separated from the reaction mixture by sedimentation.