SU1425173A1 - Method of washing sodium bicarbonate sediment - Google Patents

Abstract

This invention relates to methods for washing sodium bicarbonate sludge and reducing the loss of alkaline sodium compounds from the sludge and washing soda liquor. Sodium bicarbonate sludge is washed on a drum vacuum filter with soda-containing and non-containing liquids, fed to the washing zone with two successive streams, a non-containing liquid is fed through the sludge during the sludge flow, and the soda-containing liquid is fed second.

Description

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The invention relates to methods for washing sodium bicarbonate sludge on drum vacuum filters and can be used in the chemical industry in the production of soda ash.

The purpose of the invention is the yMeHbojeHwe loss of sodium alkaline compounds from sludge and soda-containing wash liquid.

The method is carried out as follows.

The first discharge tank is supplied with a non-containing weak liquid obtained in a distiller of a weak liquid from condensates of a distillation gas cooler and a soda gas distillation condenser. Non-water-containing weak liquid Bone contains 0.20 g / l NaCl and 0.2-1 g / l NNH- In the second pressure tank serves soda-containing weak liquid from the soda-gas washer, containing, g / l: NaaCOs 30 -60, NaCl 0.3-0.6, NHg 3-10. Each pressure tank is connected to a corresponding trough for receiving non-containing and co-containing liquids. From the first trough, the non-containing washing liquid is fed in a continuous stream to the filter in the washing zone of the precipitate. A second stream of continuous sludge is fed into the washing zone with the co-containing wash liquid from the second trough.

During the washing of the sodium bicarbonate sediment with a non-aqueous washing liquid, 85-90% of the mother liquor is displaced into the filtrate, and during further washing with the soda-containing washing liquid, another 9-14% of the mother liquor and the main amount of the first non-containing washing liquid is displaced into the filtrate. The flow rate of non-water-containing and soda-containing iibiBHix liquids is 0.3-0.5 m each per 1 ton of soda.

In the case when, according to the operating conditions of the filter, it is advisable to supply that washing of sodium bicarbonate sediment with more than two flows of washing liquid, proceed in the same way as: the co-containing washing liquid is supplied separately from the non-water-containing one after the latter.

Example. A suspension of sodium bicarbonate from the carbonation column containing 97 ml of the liquid phase, g-eq / l: NH4CI 3.56; NaCl 1.43, ammonia compounds 4.80, and in 29 g of solid phase sodium bicarbonate, filtered under vacuum of 0.012–0.013 MPa on a Büchner funnel with a diameter of 60 mm. A wire filter mesh is used as a filter septum.

At the end of the actual filtration period of 5 s, the sodium bicarbonate precipitate is pre-dried under vacuum by blowing air through it at room temperature for 10 s. Then the precipitate is washed with non-water-containing weak soda-liquid production (NaCl content is 15 g / l) in an amount of 7.1 ml and after 5 seconds under vacuum, the precipitate is washed with weak-containing soda

Liquid soda production in the amount of 7.1 ml (the content of Na2COz is 52 g / l and NaCl 0.5 g / l). Then the precipitate is dried under vacuum for 60 s. The consumption of washing liquids per 1 ton of soda is 0.4 m each. The filtrate contains

0 g-eq / l: NH4C1 3.17; NaCl 1.41; ammonia compound 4.44.

The precipitate obtained in an amount of 34.35 g contains May. %: NaHCOa 73.9; NagCOa 6.1; chlorides in terms of NaCl 0,25; The rest is ammonia compounds, moisture.

The yield of soda ash from the washed sodium bicarbonate precipitate of this composition is 52.7%.

Losses of alkaline sodium compounds from sludge and soda-containing washes

0, the washing liquid is 2.6%.

To obtain comparative data

with a known method conducted a similar

experience in the same conditions, but with the filing of both

washing two separate streams of soda containing weak soda liquid. The indicated washing liquid, containing 26 g / l of Na2CO3 and 0.5 g / l of NaCl, is successively carried out in two stages of 7.1 ml to wash the precipitate. The result is a filtrate of the following composition, g-eq / l:

0 NH4C1 3.12; NaCl 1.43; ammonia compound 4.44. Sediment received 34,05 g, the content of components in it, May. %: NaHCOs 74.9; Na2C03 5.1; chlorides in terms of NaCI 0.25; the rest is ammonia compounds, moisture.

5 The yield of soda ash from the sodium bicarbonate precipitate washed in a known manner is 52.4%. The loss of alkaline sodium compounds from the precipitate and the washing-containing soda-containing liquid during washing according to a known method is

0 3.9%.

Technical and economic advantages of the proposed method of washing the sodium bicarbonate precipitate compared to the known method consist in a decrease in washing

5 losses of alkaline compounds of sodium from 3.9 to 2.6%, an increase in the yield of soda ash to 52.7 against 52.4%, an increase in the concentration of ammonium chloride in the filtrate from 3.12 to 3.17 g-eq / l (on 0.25%).

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Claims (1)

Invention Formula A method of washing sodium bicarbonate sludge on a bar.abann vacuum filter of co-containing and non-containing liquids, which involves supplying the washing liquid 55 to the washing zone in two successive streams, characterized in that, in order to reduce the loss of alkaline sodium compounds from the precipitate and the washing 1425173 34 liquid containing liquid, the first stream containing liquid, and the second one - containing non-saturated liquid.