Method for controlling sodium nitrate quality in vacuum cooling crystallization technology

A technology of vacuum cooling and product quality, applied in solution crystallization, alkali metal nitrate, chemical instruments and methods, etc., can solve problems such as low sodium nitrate content, products that do not meet the requirements of high-quality products, and difficult to remove.

Active Publication Date: 2013-04-17
CHANGSHA DESIGN & RES INST OF CHEM IND MIN +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] However, in the process of producing sodium nitrate with sodium nitrate ore, there will be a small amount of sodium chloride, sodium sulfate and sodium nitrate (Na 2 SO 4 ·NaNO 3 ·H 2 O) Precipitation, sodium chloride, sodium sulfate and sodium nitrate are wrapped around the sodium nitr...

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  • Method for controlling sodium nitrate quality in vacuum cooling crystallization technology
  • Method for controlling sodium nitrate quality in vacuum cooling crystallization technology

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Embodiment 1

[0023] This embodiment includes the following steps:

[0024] (1) By controlling the parameters of the evaporation system, the content of sodium nitrate in the evaporated high-temperature mother liquor is 900g / l (the temperature of the high-temperature mother liquor is 135°C, the content of sodium chloride is 75g / l, and the content of sodium sulfate is 30g / l), and then sent to Three-stage vacuum cold crystallizers connected in series for cooling and crystallization;

[0025] The feed liquid temperatures of the three-stage series crystallizers are 77±1°C, 55±1°C, and 35±1°C respectively;

[0026] (2) Add water during the vacuum cooling and crystallization process to suppress the crystallization of sodium chloride and sodium sulfate during the vacuum cooling and crystallization process. The volume of additional water is 18% of the volume of the high-temperature mother liquor (all added to each stage of crystallizer), Obtain sodium nitrate slurry;

[0027] (3) In the elutriatio...

Embodiment 2

[0031] This embodiment includes the following steps:

[0032] (1) By controlling the parameters of the evaporation system, the content of sodium nitrate in the evaporated high-temperature mother liquor is 950g / l (the temperature of the high-temperature mother liquor is 140°C, the content of sodium chloride is 85g / l, and the content of sodium sulfate is 35g / l), and then sent to Four-stage vacuum cold crystallizers connected in series for cooling and crystallization;

[0033] The feed liquid temperatures of the four-stage series crystallizers are 85±1°C, 60±1°C, 50±1°C, and 35±1°C respectively;

[0034] (2) Add water during the vacuum cooling and crystallization process to inhibit the crystallization of sodium chloride and sodium sulfate during the vacuum cooling and crystallization process. The volume of additional water is 22% of the volume of the high-temperature mother liquor (all added to each stage of crystallizer), Obtain sodium nitrate slurry;

[0035] (3) In the elutr...

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Abstract

The invention discloses a method for controlling sodium nitrate quality in vacuum cooling crystallization technology, which comprises the following steps: 1, controlling the content of sodium nitrate in a high-temperature mother liquor in a vacuum cooling crystallization system as 850-1000 g/1; 2, during the vacuum cooling crystallization process, adding water to restrain separation by crystallization of sodium chloride and sodium sulfate, acquire sodium nitrate slurry, and reduce generation of fine grains; and 3, in an elutriation device, washing sodium nitrate slurry with water, during the washing process, performing mechanical stirring or gas stirring to re-dissolve separated sodium chloride, sodium sulfate, and part of darapskite. And under the action of echanical stirring or gas stirring, the darapskite not re-dissolved floats upwards on the liquid surface in the foaming form and overflows to the evaporation process for re-dissolution treatment. The washing solution goes back to the evaporation process. The method can reduce the content of sodium sulfate and sodium chloride in sodium nitrate products and enable the sodium nitrate content to meet the requirement of technical-grade superior products.

Description

technical field [0001] The invention relates to a method for controlling product quality in a sodium nitrate vacuum cooling crystallization process. Background technique [0002] Experiments have shown that sodium nitrate can replace traditional high-temperature salt and be used in solar heat transfer and heat storage systems, but sodium nitrate must meet the requirements of superior products. Compared with the first-class sodium nitrate, the high-quality sodium nitrate has obvious price and market advantages. [0003] Sodium nitrate product quality standard, see Table 1. [0004] Table 1 National Standards for Industrial Sodium Nitrate (GB / T4553—2002) [0005] [0006] At present, the crystallization process of sodium nitrate at home and abroad mainly adopts traditional freezing or natural cooling crystallization, but its production efficiency is relatively low, the production capacity is small, and the stability of product quality is not good. [0007] Compared with ...

Claims

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Application Information

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IPC IPC(8): B01D9/02C01D9/00
Inventor 戴斌联杨灿辉陈伟来周作琪程先明峁晓宝顾建龚增德王新梅宋玉东
Owner CHANGSHA DESIGN & RES INST OF CHEM IND MIN
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