SU1819854A1 - Method of sodium hydrocarbonate producing - Google Patents

Description

The invention relates to methods for producing sodium bicarbonate by carbonization of an ammoniated brine and may find application in the chemical industry, in the production of soda.

The purpose of the invention is to reduce the moisture content of the product.

According to the invention, in a method comprising contacting a pre-carbonized brine with ammonia, followed by carbonization of the brine in a carbon column with a CO2-containing gas supplied to the column inlets I and II, contacting the pre-carbonized brine with ammonia is carried out by supplying a gas containing ammonia to the II input in a mass ratio in a gas of ammonia and carbon dioxide NH3: CO ₂ = 1: (3-7).

With this gas. the column input fed to II is prepared by passing a pre-compressed COg-containing gas through ammonia condensates of soda production.

The resulting crystals of sodium bicarbonate are separated on filters.

Distinctive features of the prototype features of the method are the following:

supply of ammonia-containing gas to II · input of the carbonization column;

the ratio of gases supplied to And the entry of the column. INZ: COg = 1: (3-7):

’The use of compressed CO2-containing gas preliminarily passed through ammonia condensates of soda production for supplying to the second input of the column.

The presence of ammonia input in COg = contained gas I), which provides the ratio Na2N: COg = 1: (3-7), makes it possible to obtain sodium bicarbonate crystals with a moisture content of 10-20% less than by known methods (the amount of moisture in the filter the precipitate obtained in a known manner is taken as 100%). It should also be noted that the presence of ammonia in the input gas II slightly increases the productivity of the column, which is apparently due to the catalytic effect of ammonia on the carbonization process.

1 819 854 A1

When the amount of ammonia introduced in II is reduced (INZ: CO2> 1: 7), the quality of sodium bicarbonate crystals deteriorates, as in the known method, irregular crystals fused, which causes an increase in their moisture content on the filters.

A prohibitive increase in the amount of ammonia introduced into the II input of the carbonization column (1 \ 1H3: CO2 <1: 3), without further reducing the moisture content of the crystals, promotes crystallization together with sodium bicarbonate of ammonium bicarbonate, which in turn leads to an increase in energy consumption for calcination.

Example!. Ammonia condensate of soda production (for example, a condensate of a refrigerator or a distillation condenser) in an amount of 350 kg, containing 9.2 mol / L of ammonia and 3.6 mol / L of carbon dioxide, is fed to the adsorber at a temperature of 55 ° C. There, in a countercurrent to condensate, a compressed gas of calcining kilns with a temperature of 110 ° C is supplied in an amount of 610 kg, including carbon dioxide 300 kg. As a result of the interaction of the condensate with gas, 48 kg of ammonia and 33 kg of carbon dioxide are transferred to gas. In this case, a ratio of 1MH3: CO2 = 1: 7 is achieved. To improve the desorption of ammonia, water vapor may be introduced into the bottom of the stripper. The resulting gas is fed to the II input of the carbonization column, where 7000 kg of ammonized pre-carbonized brine containing 1550 kg of NaCI, 920 kg of (NH4) ₂ CO3 and 340 kg of NH4OH are fed.

In the column, the carbonized ammonium brine is carbonized first with gas II, and then I inlets. The resulting suspension in the amount of 7680 kg is filtered, washed and get 1980 kg of a wet precipitate of sodium bicarbonate containing 16.5% water. Precipitate of sodium bicarbonate. obtained in similar conditions by a known method, contains 20.3% moisture.

. PRI me R 2. Ammonia condensate soda production in the amount of 650 kg

containing 10.8 mol / L ammonia and 4.5 mol / L carbon dioxide, they are treated in a stripper with compressed gas of calcareous kilns in an amount of 520 kg, including 257 kg of carbon dioxide. This produces gas. containing 111 kg of ammonia and 333 kg of carbon dioxide, which corresponds to the ratio Inz'.SOG = 1: 3. Further, similarly to the previous example, this gas is fed to the II input of the carbonization column, to the I input of which CO2-containing gas is supplied. 6870 kg of ammoniated brine containing -1550 kg of NaCI, 920 kg of (NH4) 2CO3, 210 kg of NH4OH are supplied for carbonization. At the outlet of the column, 7650 kg of sodium bicarbonate suspension are obtained. The precipitate was separated on the filters, washed, and 1930 kg of wet sediment containing 14.6% water were obtained.

Technical appraisal and economic advantages of the proposed method, compared with the known method, consist in reducing the humidity of the obtained sodium bicarbonate from 18-20 to 14.6-16.5%, which allows 25 to significantly reduce energy consumption for its calcination.

Claims (2)

Claim 30 1, A method of producing sodium bicarbonate, comprising contacting a pre-carbonized brine with ammonia, followed by carbonization of the brine in a carbon column with a CO2-containing gas, πό35 supplied to the 1st and 5th inlets of the column, separating the crystals of sodium hydrogen carbonate on the filters, characterized in that , in order to reduce the humidity of the product, the contacting of the pre-carbonized brine with ammonia is carried out by supplying ammonia-containing gas to the Pth inlet at a mass ratio of ammonia and carbon dioxide in the gas ПНз: СО2 = 1: (3-7). 2. The method of claim. 1, with the _I otlichayuschiy45 topics. that the gas supplied to the llth inlet of the column is prepared by passing a pre-compressed COg-containing gas through ammonia condensates of soda production.