阅读说明：本技术 一种二水湿法磷酸生产工艺 (Dihydrate wet process phosphoric acid production technology ) 是由 韦仕朝 于 2021-11-01 设计创作，主要内容包括：本发明公开了一种二水湿法磷酸生产工艺,包括如下步骤：当磷矿中倍半氧化物杂质总含量超过2.3%时,将反应料浆中的游离硫酸根从25g/l-30g/l提升到35g/l以上；在消化槽养晶过程中,从反应槽1室取部分料浆加入到消化槽A槽,让料浆中的磷酸二氢钙与过量的硫酸根反应,形成二水硫酸钙石膏,进而降低滤液中的硫酸根含量；为确保反应系统物料平衡,在消化槽C槽过滤给料泵出口增加一根管道,将等同于从反应槽1室取出的多余料浆量返回反应槽1室。本发明能够实现磷矿分解率的提升,磷石膏不溶磷可降低0.1%。本发明方法对提高磷收率,稳定产品稀磷酸质量有益,给企业带来较大的经济效益,适用于所有湿法磷酸生产企业。(The invention discloses a dihydrate wet-process phosphoric acid production process, which comprises the following steps: when the total content of sesquioxide impurities in the phosphorite exceeds 2.3 percent, the free sulfate radical in the reaction slurry is increased from 25g/l to 30g/l to more than 35 g/l; in the crystal growing process of the digestion tank, part of slurry is taken from the reaction tank 1 chamber and added into the digestion tank A, so that calcium dihydrogen phosphate in the slurry reacts with excessive sulfate radicals to form calcium sulfate dihydrate gypsum, and the sulfate radical content in the filtrate is reduced; to ensure the material balance of the reaction system, a pipeline is added at the outlet of the filter feeding pump of the digestion tank C, and the excess slurry quantity which is equal to the quantity taken out from the reaction tank 1 chamber is returned to the reaction tank 1 chamber. The invention can realize the improvement of the decomposition rate of the phosphorite, and the content of the phosphorus insoluble in the phosphogypsum can be reduced by 0.1 percent. The method is beneficial to improving the yield of phosphorus and stabilizing the quality of the product diluted phosphoric acid, brings great economic benefit to enterprises, and is suitable for all enterprises producing wet-process phosphoric acid.)

1. A dihydrate wet-process phosphoric acid production process is characterized by comprising the following steps:

when the total content of sesquioxide impurities in the phosphorite exceeds 2.3 percent, the free sulfate radical in the reaction slurry is increased from 25g/l to 30g/l to more than 35 g/l; ensuring excessive sulfate radicals and reducing the loss of eutectic phosphorus;

secondly, in the crystal growing process of the digestion tank, part of slurry is taken from a reaction tank 1 and added into a digestion tank A, calcium dihydrogen phosphate in the slurry reacts with excessive sulfate radicals to form calcium sulfate dihydrate gypsum, and the content of the sulfate radicals in the filtrate is further reduced;

and thirdly, in order to ensure the material balance of the reaction system, a pipeline is added at the outlet of the filtering and feeding pump of the digestion tank C, and the excess slurry quantity which is equal to the quantity of the excess slurry taken out from the reaction tank 1 chamber is returned to the reaction tank 1 chamber.

Technical Field

The invention relates to the technical field of wet-process phosphoric acid production, in particular to a reaction system for producing phosphoric acid by a dihydrate wet process and a process for controlling the content of dilute phosphate radical of a product.

Background

The wet-process phosphoric acid dihydrate is a mature one in the current wet-process phosphoric acid production process, and is widely popularized due to the wide adaptability to mineral substances. Along with the continuous exploitation and consumption of phosphorite resources, the quality of phosphorite gradually slides down, wherein the more prominent expression is the increase of sesquioxide impurities. In general, the design of the phosphoric acid by the dihydrate wet method requires that 3% of excessive free sulfate radicals in a reaction system can ensure that the extraction rate of the phosphorite meets the requirement. When the content of the sesquioxide is increased, if the free sulfate radical is excessive and insufficient, partial phosphorite is not decomposed, and the extraction rate is reduced; when the sulfate radical is controlled to be too high, the sulfate radical in the product dilute phosphoric acid is too high, and the influence on downstream products can be caused.

The inventor has not found a patent specially aiming at controlling free sulfate radicals in reaction slurry of phosphoric acid by a dihydrate wet method and product diluted phosphoric acid on a Chinese patent network at present.

Disclosure of Invention

The invention aims to solve the technical problem of how to control the content of free sulfate radicals in reaction slurry and product diluted acid, improve the extraction rate of phosphorite and stabilize the product quality aiming at the quality reduction of phosphorite.

In order to further improve the extraction rate of the phosphorite under the condition of low-quality phosphorite, the inventor collects and arranges related data through multiple experiments and analysis. The invention discloses a production process for improving the extraction rate of phosphorite, which comprises the following steps:

when the total content of sesquioxide impurities in the phosphorite exceeds 2.3 percent, the free sulfate radical in the reaction slurry is increased from 25g/l to 30g/l to more than 35 g/l; ensure the excessive sulfate radical and reduce the loss of eutectic phosphorus.

Secondly, in the crystal growing process of the digestion tank, part of slurry is taken from a reaction tank 1 and added into a digestion tank A, calcium dihydrogen phosphate in the slurry reacts with excessive sulfate radicals to form calcium sulfate dihydrate gypsum, and the content of the sulfate radicals in the filtrate is further reduced;

and thirdly, in order to ensure the material balance of the reaction system, a pipeline is added at the outlet of the filtering and feeding pump of the digestion tank C, and the excess slurry quantity which is equal to the quantity of the excess slurry taken out from the reaction tank 1 chamber is returned to the reaction tank 1 chamber.

The inventor points out that: in the step 1 of the method, the free sulfate radical control amount is determined according to the impurity content of the phosphorite, and when the total content of the sesquioxide exceeds the design value of phosphoric acid by a dihydrate wet method by 2.3 percent, the sulfate radical control amount must be increased to more than 35g/l to prevent the phosphoric acid from reacting with the impurities.

In the step 2 of the method, the slurry added into the tank A of the digestion tank is required to be slurry in the chamber 1 of the reaction tank, and the content of sulfate radicals is greatly reduced because the slurry is added into the chamber 1 of the reaction tank.

In the step 2 of the method, slurry in the chamber 1 of the reaction tank must be added into a digestion tank A, and the slurry is separated from the reaction tank after entering a digestion system, so that only the subsequent product of dilute sulfate phosphate radical is influenced, and sufficient reaction time is provided for the subsequent reaction after the slurry is added into the tank A. The specific reaction equation is as follows:

5Ca(H₂ PO₄)₂+5H₂SO₄+10H₂O=5CaSO₄.2H₂O↓+10H₃PO₄

in the step 3 of the method, the redundant slurry must be returned to the reaction tank 1 chamber, so that the material balance of the reaction system is ensured, and the reaction system is not influenced.

The invention has the beneficial effects that: the decomposition rate of the phosphorus ore can be improved, and the content of the phosphorus insoluble in the phosphogypsum can be reduced by 0.1 percent. The method is beneficial to improving the yield of phosphorus and stabilizing the quality of the product diluted phosphoric acid, brings great economic benefit to enterprises, and is suitable for all enterprises producing wet-process phosphoric acid.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

Example 1: the reaction tank of the embodiment has 6 chambers, 500ml of slurry in the 6 chambers of the reaction tank is taken, the content of slurry sulfate radical is 39g/l, 20ml of slurry in the 1 chamber of the reaction tank is taken, the content of slurry sulfate radical is 9g/l, 1000ml of beaker is used for mixing the two slurries, the slurry sulfate radical in 1000ml of beaker is reduced to 35g/l after the continuous stirring for 10 minutes, the reaction of the two slurries is proved, and the purpose of reducing the free sulfate radical of the dilute phosphoric acid radical of the product is achieved.

Example 2: according to the change of the impurity content of the ore, the sulfate radical in the 6 chambers of the reaction tank is controlled to be 40 +/-2 g/l in a certain plant, so that the filtering effect of the filter is ensured. The slurry was pumped into the digestion tank A from the reaction tank 1 by an air pump at an amount of 20m³H; and (3) carrying out sulfate radical analysis on the sample, wherein the sulfate radical content of the slurry in the chamber 1 of the reaction tank is 7-8g/l, the sulfate radical content in the chamber 6 of the reaction tank is 41 g/l, and the sulfate radical content of the filtered acid is 28 g/l.