An extractant for purifying wet-process phosphoric acid and method for extracting wet-process phosphoric acid with it

Abstract

The invention discloses an extracting agent for purifying wet-process phosphoric acid and a method of extracting wet-process phosphoric acid by the extracting agent. The extracting agent comprises the following components in mass percent: 35%-95% of n-butyl alcohol, and 5%-65% of one of isooctyl alcohol, n-butyl ether, high-carbon ketone, aliphatic amine or quaternary ammonium salt. The method comprises the following steps of defluorinating and destaining crude wet-process phosphoric acid, and carrying out 6-10-level counter-current extraction according to a ratio of the extracting agent to crude phosphoric acid being (2-5) to 1, wherein sulfuric acid is added to a crude phosphoric acid inlet in the sixth or seventh level of counter-current extraction; and washing an extracting phase by using industrial phosphoric acid in which sodium carbonate is dissolved, re-extracting by using deionized water to obtain a re-extracting liquid, finally purifying the re-extracting liquid and performing concentration to obtain the industrial phosphoric acid. The extracting agent provided by the invention has the advantages that organic matters with close and moderate boiling points is subjected to binary compound, an extracting characteristic of a compound solvent is obvious, a property is stable, the extracting agent is easy to recycle and is reused for a long time, extraction is performed under room temperature and is energy-saving, crude phosphoric acid does not need to be purified in advance, the productive technology is simple, and the production cost is low.

Description

technical field [0001] The invention relates to the technical field of phosphoric acid preparation, in particular to an extractant for purifying wet-process phosphoric acid and a method for extracting wet-process phosphoric acid with it. Background technique [0002] Phosphoric acid mainly has two production processes: thermal method and wet method. Thermal phosphoric acid is obtained by oxidizing and absorbing yellow phosphorus by electric furnace method, and the resulting phosphoric acid has a high purity; wet phosphoric acid is decomposing phosphate rock by sulfuric acid, and the obtained product contains magnesium, calcium, iron, aluminum, sulfate, Various impurities such as fluorosilicate radicals and fluoride ions vary with different ore sources. Therefore, wet-process phosphoric acid is generally used to manufacture phosphate fertilizers, and it is difficult to prepare phosphate products for other industries. Since wet-process phosphoric acid has lower energy consump...

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Problems solved by technology

[0006] 1. Primary phosphoric acid needs to undergo a series of chemical methods to remove impurities before extraction, such as sulfate and some metal ions, which makes the process complicated;

[0007] 2. During the extraction process, the viscosity of the raffinate is too high, agglomerates or inorganic salts are precipitated, making the extraction process difficult or blocking the pipeline; such as using n-butanol, etc.;

[0009] 4. The boiling point of each component of the extraction agent is not suitable, and the solvent loss per ton of product is large

If the boiling point is too high, it will not be recovered and will be lost with the acid liquid, such as tributyl phosphate; if the boiling point is too low, it will lose a lot during the evaporation of the acid liquid, such as isopropanol, diisopropyl ether or diisopropyl ether, etc. , in order to reduce solvent volatilization, low-temperature extraction is often used, which has complex process and high energy consumption; at the same time, due to the large difference in boiling point or solubility of components, the loss during use is different, the performance of the extractant changes greatly, and the process parameters are difficult to stabilize;

[0010] 5. The selectivity of the extractant to phosphoric acid is low, and the yield of phosphoric acid is low, and it can only be extracted when the acid concentration of the raw material is high, such as cyclohexanone, methyl isobutyl ketone, etc.

[0011] my country is a country with a large output of wet-process phosphoric acid, and various enterprises are also keen on developing wet-process phosphoric acid purification processes. Due to the above-mentioned problems, only a few enterprises have achieved industrialization of the extraction agent process mainly based on tributyl phosphate, but they are faced with the problem of extraction Problems such as large dose consumption, low selectivity, and high production cost

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