Study of porous phospho-gypsum composites and their properties on the basis of nostochiometric interpolymer complexes

 
SCIENCE AND INNOVATION 
INTERNATIONAL SCIENTIFIC JOURNAL VOLUME 2 ISSUE 3 MARCH 2023 
UIF-2022: 8.2 | ISSN: 2181-3337 | SCIENTISTS.UZ 
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- data for 2000 and Russia ( 10.29 million tons) - data for 2006. It should be noted that our country 
traditionally occupies one of the leading places in the world market of phosphate raw materials 
[1]. In Russia, the largest holdings in the mineral fertilizer industry are Fosagro, EuroChem and 
Acron [7]. 
Methods and Results. 
Extraction phosphoric (orthophosphoric) acid (EPA) is the basic 
product in the production of most of the elemental phosphorus, concentrated simple and complex 
fertilizers, and feed phosphates. In our country, Khibiny Apatite concentrate is used for its 
production. In industry, there are two methods for producing phosphoric acid: thermal and 
extraction. The thermal method of producing phosphoric acid consists in the high-temperature 
reduction of phosphates and sublimation of elemental phosphorus in electric furnaces, which is 
then oxidized to phosphoric anhydride, which forms phosphoric (thermal) acid during hydration. 
The main method for producing EPA is the displacement of phosphoric acid from raw materials 
by strong acids. As the displacing acid can be used: sulfuric, nitric, phosphoric, as well as mixtures 
thereof. Over 70% of natural phosphate raw materials worldwide are processed using sulfuric acid, 
hence the name of the production method - sulfuric acid (extraction). Thermal acid is cleaner than 
extractive, even when using low quality raw materials, which is its advantage. However, at present, 
there is a decrease in the production of thermal acid, since the process of its production seems to 
be very energy intensive. In this regard, it is more expensive. However, at present, there is a 
decrease in the production of thermal acid, since the process of its production seems to be very 
energy intensive. In this regard, it is more expensive. However, at present, there is a decrease in 
the production of thermal acid, since the process of its production seems to be very energy 
intensive. In this regard, it is more expensive. 
The decomposition of apatite concentrate with sulfuric acid is described by the following 
equation (phosphoric acid dissolution of fluorapatite): 
Ca
5
(PO
4
)
3
F + 5H
2
SO
4
 + nH
3
PO
4
 + mH
2
O → (n + 3) H
3
PO
4
 + 5CaSO
4
 ∙ mH
2
O + HF 
Phosphoric acid is extracted during the reaction, and calcium sulfate and fluorinated gases 
are also formed. 
Depending on the temperature and concentration conditions of the process, calcium sulfate 
crystalline hydrates (solid phase) may precipitate in the form of dihydrate, hemihydrate or 
anhydrite. These forms of the existence of calcium sulfate when changing the mode of conducting 
the process can go from one to another. Accordingly, dihydrate, hemihydrate and anhydrite 
methods for the production of phosphoric acid are isolated. 
Calcium sulfate dihydrate or hemihydrate formed as a by-product due to the content of 
P2O5 impurities in them (undecomposed phosphate, undisturbed phosphoric acid, co-crystallized 
P2O5) is called phosphogypsum or phospho-hemihydrate, respectively. But when considering the 
problems of transportation, storage and use, both products are usually called phosphogypsum [6; 
8; nine]. 
Phosphogypsum is a white to gray color finely dispersed, close to monomineral powder, 
having high humidity when leaving the chemical plant, according to various sources, from 25 to 
45%. Its chemical composition may depend on the type of phosphate feedstock, production method 
and method of storage [8; fifteen]. 
Removing a by-product involves choosing the most reliable and economical way to 
transport and store it, taking into account the specific conditions of each enterprise. Currently, two 
main directions of phosphogypsum utilization are practiced in the world: discharge into water 

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