CS239264B3 - Combined water-purifying coagulation agent and process for its production - Google Patents

Abstract

The purpose of the solution is to enable the use of chlorine as a cheap oxidizing agent to utilize substances with a high content of divalent iron to produce a highly effective coagulant based on trivalent iron for water purification.

Description

(54) Combined coagulation agent for water purification and process for its production

The purpose of the solution is to enable the use of chlorine as a low-cost oxidant to utilize a high divalent iron content for the production of a high-performance trivalent iron coagulation agent for water purification.

BACKGROUND OF THE INVENTION The present invention relates to a trivalent iron coagulation composition for the purification of water and to a process for its preparation from sulfuric acid and acid systems resulting from the production of titanium dioxide.

In the description of the invention to U.S. Pat. No. 232,520 discloses a trivalent iron coagulation agent for the purification of water, the functional components of which are ferric sulphate, sulfur trioxide monohydrate and ferric oxide in aqueous solution or in aqueous suspension.

A process for its preparation is also described, wherein sulfuric acid monohydrate and ferric oxide are reacted at elevated temperatures in the reaction mixture from the starting components, i.e. dilute sulfuric acid, acidic systems and ferric oxide, and the divalent iron present is oxidized with an oxidizing agent which does not increase. and does not alter the dissolved salt content, such as hydrogen peroxide.

However, these oxidizing agents are expensive, especially when larger amounts of iron (II) are present in the starting components. This disadvantage solves MS. No. 232,520, it is a coagulant for the purification of water based on trivalent iron, the functional components of which are ferric sulphate, sulfur trioxide monohydrate and ferric oxide in an aqueous solution or in an aqueous suspension, and its other component is ferric chloride present in moles / l, corresponding to one-third moles of oxidized divalent iron from the starting mixture, calculated on the volume of the product obtained.

In the preparation of the coagulating agent of the dependent invention, the divalent iron is oxidized from the starting mixture with chlorine.

It is an advantage of the invention that the use of a less expensive oxidizing agent will allow the processing of starting materials containing a greater amount of divalent iron, while maintaining a high water purification efficiency of the product.

Example 1

In a vessel made of corrosion-resistant material equipped with a stirrer and a heater, 143 g of acidic systems were loaded, containing: 22.45 g Fe ²⁺ , 0.14 g Fe ²⁺ , 32.5 g H 2 SO 4 / 0.33 mol / next to other admixtures.

Added 1 000 ml of unconcentrated de-ironed fissionable acid (h = 1,285) from the production of titanium dioxide, containing 3,49 mol / l H ₂ SO ₄ / 28,5% by weight / and 15,2 g / 1 Fe ²⁺ as main impurity .

The mixture was stirred with heating at 40 ° C for 15 minutes.

While stirring, chlorine gas was then introduced in successive portions to the bottom of the vessel for 30 minutes. Then 245 g of sulfur trioxide monohydrate in the form of 136.3 ml of 98¾ ^H 2 ^SO 4 = * 836) were added and the batch weighed 340.5 g of Fe ₂ O 4 in powder form, resulting from the pickling of the steel with hydrochloric acid.

The reaction vessel was covered with a lid with a stirrer hole and heated up to boiling point (116 ° C), whereupon the heating intensity was reduced to roughly cover the loss of heat to the surroundings. The total reaction time was 100 minutes.

After completion of the reaction, the contents of the flask were diluted to 1,573 ml by addition of water, stirring was stopped and the flask was allowed to stand. After 120 minutes decanted product from the sediment was decanted and left in the reaction vessel for further coagulant preparation.

The product had the following composition: Fe ^ ⁺ et 170.7 g / l, Fe ²⁺ s = 0.3 g / l, H ₂ SO ₄ * »0.07 mol / l, neutralizing capacity to pH 7» 9.32 mol / l NaOH, h «1.55, the content of Fe ₂ / SO _4/3" 585 g / 1 _FeCl3 content «23.2 g / 1 solids content of the suspension / Fe ₂ O ₃ + insoluble residue / 2 , 2 g / l.

The invention finds use in the chemical industry.

Claims (2)

SUBJECT OF THE INVENTION Coagulation agent for the purification of water based on trivalent iron according to the art. No. 232,520, the functional components of which are ferric sulphate, sulfur trioxide monohydrate and ferric oxide in aqueous solution or aqueous suspension, characterized in that the other component is ferric chloride present in an amount of one third of moles % of the oxidized divalent iron from the starting mixture, calculated on the volume of the product obtained. 2. A process for the production of a water purifying agent according to claim 1, wherein the bivalent iron from the starting mixture is oxidized with chlorine.