Method for producing broad-concentration phosphoric acid and clean plaster by middle-low grade phosphorus ore wet process

Abstract

The invention discloses a method for producing broad-concentration phosphoric acid and clean plaster by a middle-low grade phosphorus ore wet process. The method comprises the following main procedures: (1) adding powder phosphorus ore and phosphoric acid to a semi-acid hydrolysis reaction tank for acid hydrolysis reaction at 95-105 DEG C, and carrying out solid-liquid separation on the slurry obtained by acid hydrolysis after full acid hydrolysis reaction; (2) transferring phosphoric acid clear liquid separated in procedure (1) into a crystallization tank, adding sulfuric acid and carrying out crystallization at 70-110 DEG C, and carrying out solid-liquid separation after full reaction, wherein, a liquid phase is the phosphoric acid to be prepared and a solid phase is the functional clean plaster to be prepared; and (3) transferring residue slurry separated in procedure (1) into a secondary acid hydrolysis reaction tank, adding water, carrying out secondary acid hydrolysis and recrystallization on the residue slurry at 65-80 DEG C, carrying out solid-liquid separation after full reaction, transferring the obtained separation liquid into procedure (2), and discharging the separated solid residues. The method of the invention has the characteristics of high production efficiency, high phosphorus resource recovery rate, strong production capacity, good economic benefit, strong operability and the like.

Description

technical field [0001] The invention relates to the development and utilization of low- and medium-grade phosphate rocks, and more specifically relates to a method for producing phosphoric acid with a wide concentration range and functional clean gypsum by using a wet method using low- and medium-grade phosphate rocks as raw materials. Background technique: [0002] With the gradual depletion of phosphate rock resources in the world, all countries are very concerned about the development and utilization of low-grade phosphate rock. Many scholars in China have carried out in-depth research on the wet production of medium and low-grade phosphate rock. For example, the research group of Professor Liu Daijun from the Department of Chemical Engineering of Sichuan University has long been committed to the research on the wet production of medium and low-grade phosphate rock, and has achieved various results. Research results, such as the two-stage dihydration process for high-sili...

AI Technical Summary

Problems solved by technology

Although the first two processes have passed the pilot test, these processes are based on the improvement of the traditional dihydrate process, and the obtained phosphoric acid is 27%P 2 o 5 The low concentration of phosphoric acid below, the gypsum obtained is of high quality, but it is still dihydrate gypsum. If it is to be used as building gypsum, it needs to be calcined, and the energy consumption is high; at the same time, the device is large and the production capacity is limited.

[0003] China's phosphate rock resources are becoming increasingly depleted. Quite a few low- and medium-grade phosphate rocks have small crystal grains, making mineral processing extremely difficult. It is difficult to use the existing wet process. The content of impurities is high, the reactivity is poor, and the solids are seriously fouled in the filtration. The obtained phosphogypsum not only has a high liquid content, but also has a large loss of phosphorus, and is difficult to use.

For these medium and low-grade phosphate rocks, not only the ordinary semi-aqueous process is difficult to operate, but also the adaptable dihydric process is also difficult to carry out.

[0004] Based on the fact that phosphate rock resources are becoming increasingly depleted, the existing wet process is difficult to achieve the ideal technical effect of low-grade phosphate rock, and people's demand for phosphorus chemical products is increasing, it is urgent to develop a method that can directly obtain high-grade phosphate rock Concentrated phosphoric acid and high-quality architectural hemihydrate gypsum can also be obtained with lower concentration of phosphoric acid and high-quality functional dihydrate gypsum, and can be adapted to the new wet production of low- and medium-grade phosphate rock with high impurity content and wide concentration A wide range of phosphoric acid and clean gypsum processes in order to meet different industrial production requirements and market demands

Images