SU495282A1 - Method for producing barium chromate - Google Patents

Description

one

The invention relates to the field of synthesis of mineral pigments, in particular to the technology for producing barium chromate.

A known method for producing barium chromate used to synthesize yellow barium inks is by reacting patromate with barium chloride solution at 80-85 ° C and a slight excess of my sodium chromate versus stoichiometric in the equation:

BaCl2 + Na2CrO4 BaCrO4 + 2NaCl. (one)

The resulting precipitate of barium chromate is separated from the mother liquor, washed from soluble salts and dried at 100 ° C.

The disadvantages of this method are that during the precipitation of precipitate chromate barium is poorly filtered, it has an average filtration rate of 1.5-2.0 ml / cm-min and is difficult to wash off harmful impurities and, consequently, an increased content of impurities in the product up to 1% of water-soluble salts with a BaCgO4 content of 95%).

To increase the filtration rate and reduce the content of water-soluble impurities in the product, initial reagents (sodium chromate and water-soluble barium compound) are suggested to be taken in an amount that provides a solids content in the reaction mixture equal to 60-100 kg / m and the resulting suspension of barium chromate before filtration is about. work with live steam for 1-2 hours

As a barium compound, in addition to water-soluble barium salts, it is advisable to use barium hydroxide.

The mother liquor after separation of the resulting equation:

Ba (OH) 2 + Na2CrO4 BaCr04-f2NaOH (2)

The precipitate of barium chromate, which does not contain side impurities, is sent to the production of chromium compounds.

Example 1. A 5 m sodium monochromate solution containing 93 kg / m Na2CrO4 is poured into the reactor, heated to 85 ° C, and then 4.2 m of a hot barium hydroxide solution (114 OH) 2, which is 98% of the required amount for the formation of barium chromate according to equation (2).

9.2 m of pulp is obtained with a content of 77 kg / m of BaSgO4, which is then treated with live steam for 1 hour with stirring at a temperature of 100 ° C. After that, the pulp is filtered with an average filtration rate of 3.0 ml / cm-min on the filtrate, and the precipitate is washed of impurities (NaOH, Na2CrO4) with hot water. The washed precipitate of barium chromate is dried at –100 ° С to obtain

3

product containing weight %: 96.0 BaSgO4; 0.8 H2O; 0.4 water soluble salts.

Example 2. A 5 m sodium monochromate solution with a pH of 7.0 and a content of 125 kg / m of Na2CrO4 is poured into the reactor, heated to 85 ° C and then 4.7 m of a hot barium chloride solution with a content of 167 kg / m YOU, which is 98% of the required amount for the formation of barium chromate by the equation

(one). 9.5 m of pulp is obtained with the content

 100 kg / m VaSgO4, which is then treated with live steam for 2 hours with stirring at a temperature of 100 ° C. After that, the pulp with |) is filtered at an average filtration rate of 2.8 ml / cm-min by the filtrate, and the precipitate is washed of impurities (NaCl and Na2CrO4) with hot water. The washed precipitate of barium chromate is dried at –100 ° С to obtain

product, content, weight %: 96.0 BaSgO4; 0.8 NAO; 0.3 water soluble salts.

Claims (2)

1. A method of producing barium chromate by reacting chromate w, a Christmas tree with a barium compound followed by filtration and drying of the precipitate, is different By the fact that, in order to increase the filtration rate and reduce the content of water-soluble impurities in the product, the initial reagents are taken in an amount that ensures the solid content in the reaction mixture is equal to 60-100 kg / m and the uus suspension is filtered with an acute filter before filtration. steam for 1-2 hours 2. The method according to claim 1, characterized in that barium is used as a barium compound. barium hydroxide.