Wet-process phosphoric acid extraction tower cleaning method

Abstract

The invention discloses a wet-process phosphoric acid extraction tower cleaning method. The method comprises the following steps of performing high-pressure water physical cleaning on the interior of an extraction tower, and opening a channel in dirt; performing chemical cleaning on the interior of the extraction tower by adopting a cleaning solution with the temperature of 70 DEG C or above, and controlling the pressure intensity of the cleaning solution to be 0.05 MPa or above in the chemical cleaning process, so that the hard scale is converted into soft scale; and performing high-pressure water physical cleaning on the interior of the extraction tower, so that soft dirt falls off and is discharged outwards, and finishing cleaning of the extraction tower. The cleaning method has the advantages of being short in cleaning period, low in cleaning cost, high in cleaning efficiency, good in cleaning effect, safe, environmentally friendly and the like, efficient and thorough cleaning of the wet-process phosphoric acid extraction tower can be achieved, the use value is high, and the application prospect is good.

Description

Technical field [0001] The present invention relates to a cleaning method of a wet phosphoric acid extraction column. Background technique [0002] The wet phosphoric acid process was carried out using concentrated sulfuric acid and phosphorite to prepare phosphoric acid, and the amount of sulfate precipitate which filtrates the concentrated sulfuric acid with phosphorite to remove the calcium sulfate precipitate, the obtained filtrate is a phosphoric acid solution. In order to further achieve high quality phosphoric acid, the phosphoric acid solution is continued. During the purification of the phosphoric acid solution, the extraction tower is a key device of the purification process, and in order to increase the extraction rate, the extraction tower is selected by the tower multi-stage ring structure. However, during the extraction process, the extractant is alternated with the phosphoric acid, and there is a large amount of crystal salts, which are stacked together to form dim...

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Problems solved by technology

In addition, the volume of the extraction tower is relatively large and the structure is complex; the fouling composition of the extraction tower is complex, the texture is hard, and the amount of scale is large; the site construction conditions are harsh, and the extraction agent is a flammable solvent, which requires high explosion-proof grades, so the existence of the above factors , put forward higher requirements for the cleaning of the extraction tower

[0003] The cleaning method of existing extraction tower mainly comprises chemical cleaning and physical cleaning, yet, these two kinds of methods still have following defects, as the shortcoming of chemical cleaning has: (1) cleaning time is long, because scale amount is big, and scale quality is complex and hard , the required cleaning time is about 30 days; (2) The cleaning rate is low, due to the complex structure of the equipment, there are dead corners in the cleaning process that cannot touch the cleaning liquid, so the cleaning rate cannot be guaranteed; (3) The amount of sewage is large, due to the cleaning In the process, the acid-base is alternated many times and replaced with water, so the amount of sewage discharge is large, and the cost of environmental protection treatment in the later stage is high; (4) the cleaning cost is high. consumes a lot

The disadvantages of physical cleaning are: (a) safety issues. Due to the hard scale, the pressure of the cleaning equipment is between 90-120MPa, which will damage the equipment and have huge safety hazards for the operators and nearby staff; (b) environmental protection The problem is that due to the heat released when the equipment hits the scale during the physical cleaning process, the methyl isobutyl ketone (MIBK) contained in the scale is released, which not only pollutes the environment, but also harms the human body; (c) the economic cost is high, Because physical cleaning requires high pressure on equipment, both the investment in equipment and the wearing parts of the actuator are large, and the loss of equipment is also large. At the same time, high-pressure equipment requires high quality and skills of operators and requires frequent Changing hands, so the labor cost is high

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