SU749873A1 - Method of preparing ferric oxide pigments - Google Patents

Description

one

The invention relates to the treatment of inorganic Materials for enhancing their pigmenting properties, in particular to methods for producing iron oxide pigments, and can be used in the metallurgical, paint and varnish industry and in the building materials industry.

A known method for producing red iron oxide pigment by thermal decomposition of vitriol using; multistage washing with water, where the concentration of the solid component in the aqueous suspension is 100-110 g / l. The pigment is treated with 5–10% soda solution up to pH 66.5 U1-,.

The disadvantage of this method is a sufficiently large flow of water during washing, amounting to 10 to 20 tons per ton of washable pigment.

The closest in technical essence to the present invention is a method for producing iron oxide pigment by thermal decomposition 25 of a spent pickling hydrochloric acid solution, for example, by etching carbon steels. The decomposition of the solution is produced in the combustion zone of the gas with excess air, at: 3Q

this is the temperature in the reactor. cder; live 480C. The powder coming from the reactor is mixed with 5-B-fold red water. After settling, the water is drained into the sewer. Upon thermal decomposition of the spent pickling solution, hydrogen chloride is directed to water absorption to produce hydrochloric acid sweat 2.

The disadvantage of this method is the contamination of the pigment (iron oxide) with soluble iron salts, increased acidity of the product, high consumption of wash water, low density of the suspension 120-250 g / l. Used wash water containing soluble iron salts and high acidity is discharged into the sewage system, thereby reducing the yield of the target products, contaminated by chemical substances. When flushing with water, the pigment may be contaminated with concomitant water. The decomposition temperature is maintained at 480 ° C, which makes it possible to obtain a pigment of approximately the same color tone of red.

The purpose of the invention is to expand the color gamut of iron oxide pigments, increase their purity and yield and reduce the consumption of wash water, as well as obtaining red, red-lilac, and lilac pigments. This is achieved by the described method of producing iron UNs. Pigmento from carbonaceous steels of hydrochloric acid solutions used for etching. By thermal decomposition during the combustion of combustible gas in air flow at 480-520, 550620 and 650--50 C, respectively, to obtain red, red-lilac and lilac pigments with subsequent washing. This pigment has a steam condensate with a pigment content of 300-350 kg / m, a countercurrent in three stages, so that in the first stage the washing is carried out with a washing solution from the second stage, in the second stage - with a washing solution from the third and at the third stage the pigment is washed initial stage steam condensate, and exhaust vapor condensate is fed to mixing with source hydrochloride solution. The difference of the method is that the thermal decomposition of the initial solution is carried out at 480-750 s, and the pigment is washed with countercurrent steam condensate in the three stages as described above, and the spent steam condensate is mixed with the initial hydrochloric acid solution. washing is carried out when the pigment content in the steam condensate is 300-350 kg / m. Kr $ N addition, with the aim of obtaining the pigment of Red, red-lilac and lilac color, thermal decomposition is carried out according to this method, respectively, at the indicated temperatures above. The hydrochloric etching solutions worked on carbonaceous steels during thermal decomposition form iron oxide and red iron oxide pigments. In order to expand the color product numbering of the target product, the decomposition temperature should be maintained in the range of 480 to 750 ° C. The dependence of the temperature effect in 3 times the amount of color on the studied pigment is given in Table. 1, from which it follows that the most p749873 shades of pigment with Homogeneous TONOM are obtained at temperatures of 480-520, 550-620, 650-750 0. Table 1 Changing the tone of the iron oxide pigments depending on the temperature in the decomposition zone Ton of iron oxide with 480 decomposition of the solution is incomplete. 480-520 red 510-540 red-lilac, no uniformity 550-620 red-lilac, bright 620-640 red-brown-lilac 650-750 liren, bright 750-850 bur-lilac, dim Received pigment contains from 1 to 5 wt.% {soluble salts. In a three-stage backwash of pigment steam condensate with a countercurrent, the most acceptable ratio of condensate to washable pigment is 3: 1. The process is conducted in such a way that in the first stage the washing is carried out with a washing solution from the second stage, in the second stage the pigment is washed with a washing solution from the third stage, and in the third stage the pigment is washed with the initial steam condensate. Moreover, the first and second washings are carried out with stirring, and the third in a stationary layer on the filter. The pH of the medium in the first stage is 2, in the second stage the pH is 3-4. . The total recovery ratio of soluble salts in a three-stage protrusion, when the ratio of condensate to pigment is 3: 1 is 99 and the pH of the aqueous extract is 5-6 instead of 2-3 with a single washing with a ratio of water to pigment 5: 1 (see Table 2).

1: 1.5 39 34 1: 3 67 31

4 5-6 Three-stage washing with steam condensate 17 90 3.8 0.38 1 4 1.0 99 4.0 0.03 1 4 75 23 1.5 99, S 4,0 One-stage washing

The continuation of the table.2 0.01 - 2 pigment with water,

Claims (3)

Claim 1. A method for producing iron oxide pigments from hydrochloric acid spent on etching carbon steels by thermal decomposition during combustion of combustible gas in an air stream followed by washing of the resulting pigment, characterized in that, in order to expand the color gamut of the target product, increase its purity and exit and reduce the flow of wash water, the thermal decomposition of the initial solution is carried out at a temperature of 480-750 ° C, and the pigment is washed with steam condensate countercurrent in three hundred stage, so that in the first stage, washing is carried out with a washing solution from the second stage, in the second stage with a washing solution, from the third stage, and in the third stage, the pigment is washed with the initial steam condensate, and the spent steam condensate is sent for mixing with the initial hydrochloric acid solution. 2. The method of pop. 1, different. in that the washing is carried out at a pigment content in the steam .. condensate of 300-350 kg / m ¹ . 3. The method of pop. 1, characterized in that in order to obtain a pigment of red, red-lilac and lilac color, thermal decomposition is carried out respectively at 480-520, 550-620 and 650750 ° C.