Method for crystallizing sodium thiosulfate pentahydrate

A technology of sodium thiosulfate pentahydrate and sodium thiosulfate, which is applied in the direction of thiosulfate/dithionite/polythionite, etc., which can solve the problem of small effective volume capacity of batch crystallizers and product batch differences , large floor space and other issues, to achieve stable product quality, no batch-to-batch differences, and improved production capacity

Inactive Publication Date: 2011-08-10
CITIC JINZHOU METAL +1
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

The disadvantages of the above-mentioned batch crystallization process are: 1. The unit effective volume capacity of the batch c...

Method used

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  • Method for crystallizing sodium thiosulfate pentahydrate
  • Method for crystallizing sodium thiosulfate pentahydrate

Examples

Experimental program
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Effect test

Embodiment 1

[0012] As shown in the figure, the concentration of 49Be' sodium thiosulfate solution at 80kg / m 3 The rate of h is continuously sent to the Oslo cooling crystallizer, and then sent to the heat exchanger for cooling and cooling by a circulating pump; when the temperature drops to the saturation temperature (41-42°C), seeds with a particle size of 2 mm are added at one time, and the crystallization time is 18 hours. , continue to cool down to 35-36 ° C, start to discharge the crystal slurry continuously; the discharged crystal slurry is separated from solid and liquid to obtain the finished product of sodium thiosulfate pentahydrate. The purity of the product is 99.7%, the particle size is greater than 3mm, and the production capacity is 23kg / m 3 h.

Embodiment 2

[0014] As shown in the figure, the concentration of 47Be' sodium thiosulfate solution at 60kg / m 3 The rate of h is continuously sent to the Oslo cooling crystallizer, and then sent to the heat exchanger for cooling and cooling by a circulating pump; when the temperature drops to the saturation temperature (37-38°C), a seed crystal with a particle size of 3mm is added at one time, and the temperature continues to drop to When the temperature is 30-31°C, the crystal slurry starts to be discharged continuously, and the crystallization time is 20 hours. The discharged crystal slurry is separated from solid and liquid to obtain the finished product of sodium thiosulfate pentahydrate. The product purity is 99.6%, the particle size is greater than 4mm, and the production capacity is 20kg / m 3 h.

Embodiment 3

[0016] As shown in the figure, the sodium thiosulfate solution with a concentration of 50Be' was added at 100kg / m 3 h is continuously sent to the Oslo cooling crystallizer, and then sent to the heat exchanger by a circulating pump for cooling and cooling; when the temperature drops to the saturation point (43-44°C), seed crystals with a particle size of 4mm are added at one time, and the temperature continues to drop to 37 At -38°C, the crystal slurry began to be discharged continuously, and the crystallization time was 15 hours. The discharged crystal slurry is separated from solid and liquid to obtain the finished product of sodium thiosulfate pentahydrate. The purity of the product is 99.5%, the particle size is greater than 5 mm, and the production capacity is 25 kg / m 3 h.

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Abstract

The invention discloses a method for crystallizing sodium thiosulfate pentahydrate, which particularly comprises the following steps of: continuously feeding sodium thiosulfate solution with the concentration of less than 51Be' into an Oslo cooling crystallizer and continuously feeding the obtained solution into a heat exchanger through a circulating pump for the cooling and temperature reduction; and when the temperature is reduced to a saturation temperature, adding seed crystals in one step, and continuously discharging crystal mush and carrying out solid and liquid separation, wherein the crystallization temperature is in the range of 30 to 38 DEG C and the crystallization retention time is in the range of 15 to 20 hours. In the invention, the Oslo cooling crystallizer capable of maintaining stable growth of the crystals and realizing circulation of clear liquid is used so as to provide an excellent condition for the growth of the crystals; on the basis of continuous operation, large and uniform crystals can be grown, the purity of the product reaches over 99 percent, and the granularity of the product is over 3mm; compared with a discontinuous crystallizer, the production capacity of the Oslo cooling crystallizer capable of continuously operating in unit effective volume is improved by over 30 percent; operation parameters in the continuous crystallizing process are stable; the products have stable quality and no differences among batches; and automatic control can be realized.

Description

technical field [0001] The invention relates to a crystallization method of sodium thiosulfate pentahydrate. Background technique [0002] Sodium thiosulfate pentahydrate commonly known as Haibo, molecular formula Na 2 S 2 o 3 ·5H 2 O. The batch crystallization process adopted by the existing domestic crystallization process is as follows: a sodium thiosulfate solution with a temperature of 60-80 °C and a concentration of 52-54 Be' is added to a crystallizer of a certain volume at one time, and the crystallizer adopts a serpentine tube and a device. Wall jacket double cooling. When the material temperature drops to 47-48°C, add seed crystals with a particle size of 2-5mm at one time, and the crystallization time lasts for 16-24 hours. Then the crystal slurry is released at one time, and the crystal slurry is packaged into products after solid-liquid separation, and the production capacity per unit volume is 20-25 kg / m 3 h. The disadvantages of the above-mentioned bat...

Claims

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Application Information

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IPC IPC(8): C01B17/64
Inventor 齐牧孙秀松王锋崔传海郭树志金绍祥王骞安小刚史昱金梅张玉驰张小钦王丽赵志坚郭密云于少华刘亚凤赵秀媛
Owner CITIC JINZHOU METAL
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