High-selectivity ion pair type extraction agent and method for extracting wet-process phosphoric acid by using same

Abstract

The invention discloses a high-selectivity ion pair type extraction agent and a method for extracting wet-process phosphoric acid by using the high-selectivity ion pair type extraction agent. The high-selectivity ion pair type extraction agent is prepared from the following components in mass fraction: 1-10% of aliphatic amine or quaternary ammonium salt, 20-79% of normal butanol, and 20-79% of isooctyl alcohol, n-butyl ether or high-carbon ketone. The method comprises the steps of defluorinating and decolorizing wet-process crude phosphoric acid, performing 6-10-level counter-current extraction on the extraction agent and the crude phosphoric acid with the ratio of (2-5):1, adding sulfuric acid in a 6-level or 7-level crude phosphoric acid inlet, washing extract phase, reextracting with deionized water to obtain strip liquid, purifying the strip liquid and concentrating to obtain industrial grade phosphoric acid. According to the invention, the ion pair type organic matter with strong polarity is used as extraction agent polarity regulator, has high extraction capacity and stable performance, can be cycled for a long time, can be used for extraction at room temperature and is energy-saving; the initial mass fraction of P2O5 in strip liquid is more than 38.0, the evaporation capacity of concentrated acid is low, the extraction rate is more than 86%, and more than 19kg of extraction agent is consumed by 85% phosphoric acid per ton.

Description

technical field [0001] The invention belongs to the technical field of phosphoric acid preparation, and in particular relates to a highly selective ion-pair type extractant 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

[0005] 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;

[0006] 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;

[0008] 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, the process is complicated and the energy consumption is high;

[0009] 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.

[0010] 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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