SU952739A1 - Method for processing soda-sulphate mixture - Google Patents

Description

The invention relates to non-ferrous metallurgy and can be used to process a sodosulfate mixture obtained as a by-product of alumina production.

A known method of processing a soda-sulfate mixture, according to which sodium sulfate is removed from the mixture by introducing fluorine compounds, for example, NaF, while the double salt NaF-NajSO 1 precipitates.

The disadvantages of the method are the high cost of the reagent used and the need for its regeneration for subsequent use.

The closest to the invention by. the technical essence and attainable goal is a method of processing the sodosulfate mixture, which includes dissolving the mixture in water at .5, calcareous caustification at 60 ° C, separating the precipitate by settling, evaporating the resulting solution.

The sodosulfate mixture is a double salt of the composition. About f2Ha SO.

In the case of caustification of the sodosulfate of the CaO mixture, CaO only passes into NaOH, and sodium sulfate does not undergo transformation. The amount of caustic alkali in the solution is only 5.71% or 5O g / l NaOH. This amount of caustic alkali is not enough to remove all sodium sulfate.

In order to isolate 95-96% Na2S04 from a sulphate solution, it is necessary to have a final NaOH content in the solution of 25-26%.

Therefore, the solution after causticization is either mixed with a pure caustic alkali solution containing 40-45% NaOH, or is subjected to evaporation 2.

The disadvantages of this method are high steam consumption — evaporation, low sedimentation rate after causticisation, 0.1 m / h. ,

The purpose of the invention is to reduce steam consumption for evaporation and increase the rate of settling.

The goal is achieved by the fact that, according to the method of processing, the sodosulfate mixture, which includes the burning of the mixture, the lime caustification of the solution, the separation of the precipitate by settling, the evaporation of the resulting solution, is mixed with soda before dissolving

with a solution to obtain a molecular ratio of N32CO3: Na2SO4 equal to 0.54-0.58, and calcareous caustic DIAG is carried out in two stages - 48.6-52.5% CaO of the total amount of lime at 90-95s is introduced into the first stage with separation sediment from the solution and dilution of the latter by 1.05-1.1 times, and the second stage of calibration is carried out with the remaining amount of lime.

The sodosulfate mixture is mixed with pure soda or soda present in the solution so as to obtain the molecular ratio of Ma CO to NajSO equal to 0.54-0.58. This ratio of salts ensures the caustification process in the area of formation of carbonate double salts of the composition of Na, C02CaCO 2H50. For this, the caustification process is carried out in two stages. In the first stage, the amount of CaO injected is determined by the reaction and is 48; 6-52.5%;

2NaoCO + CaO + 3H2O CaCO 2H5 0+ + 2NaOH. .

As a result of this reaction at 9095 C, caustic alkali and double carbonate salt crystals are obtained, which have a size of 0.1-0.15 mm.

which makes it easy to separate the solid phase from the bulk of the solution by settling. The separation rate of such crystals is 1-1.1 m / h.

To increase the degree of causticisation of soda, the solution with temperature is diluted 1.05-1.1 times, cooled to 50-6. and further treated with lime is 47.5-51.4% CaO for complete conversion to NaOH.

Example: A sodosulfate mixture in an amount of 28.3 g is mixed with soda, dissolved at 52.63 g of water to form a sodosulfate solution. After mixing, the solution is caustified with lime. In the first stage, lime is added at the rate of production. With an atom, only a portion of the soda is converted to caustic alkali. The solution is separated from the precipitate of double salt by settling. The resulting solution is diluted by adding 10 g of water, cooled to bare water, and the second stage of caustification is carried out with the remaining amount of lime. The precipitate is separated from the solution, which is subjected to evaporation.

A comparative analysis of the known and proposed methods is presented in Tables 1 and 2.

Table. one

iFamous 7.76 20.62

71.62

25.75 20.62 53.63 0.54 2.41

Offered 27.6 20.62 51.78 0.58 3.4

73.48

Known 5.9 20.62

 19.2 20.62 60.18 0.35

Offer58 D

jello

21.2 20.62

The proposed method allows to reduce steam consumption by 7.4-8.1 times.

100

2.18

52.5

47.5

51.4

48.6

3.6

table 2

OD

60

1.0

95

1.05

90

0.31

evaporation and 10–10.5 times the sedimentation rate.

59527396

Claims (2)

Claims of the invention are 0.54-0.58, and calcareous caustic is used. The method of processing the sulphate stage is 48.6-52.5% CaO from the mixture, including dissolving the mixture, the amount of lime at 90-95 °. lime caustic solution, with the separation of sediment from the solution and separating the precipitate by settling, dispensing the latter in 1.05-1.1 rarirovanie the resulting solution, about t for, and the second stage of causticization due to the fact that with the remaining amount of lime. The reduction of steam consumption for evaporation. Information sources, and increase in the rate of settled-taken into account in the examination of vania, before dissolving the sosolum 1. US patent number 2486318, fatty mixture is mixed with soda-ra. 23-63, 1949. to get a molecular 2. USSR author's certificate ratio NajSOz; Ma SSC equal to 814866, cl. C 01 O 5/00, 1979, tion is carried out in two stages - on the first