Double superphosphate

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Double superphosphate (Ca(H2PO4)2-H2O) in contrast to simple superphosphate has a high content of assimilable phosphorus in terms of P2O5-42-49% and doesn’t contain gypsum. Phosphorus i presented in this fertilizer in the form of water-soluble monocalcium phosphate Ca(H2PO4)2-H2O and a small amount of free phosphoric acid (2.5-5.0%).

In the manufacturing process of double superphosphate apatite (or phosphorite) is treated with sulfuric acid. It’s taken more than in the production of simple superphosphate, in order to obtain not a monocalcium phosphate, but phosphoric acid, which is used for new portion of the raw material treatment. And as a result double superphosphate is obtained.

The product is produced in granular form.

Item Parameters for grades
А B C
Form Granular product without foreign mechanical impurities
Mass fraction of assimilable phosphate (Р2О5), % not less than 21 26+/-1 not less than 22
Mass fraction of free acid in terms of Н3РО4, % not less than 1,5 not less than 1, 5 not less than 1,5
Mass fraction of potassium in terms of К2О, % not less than 5
Total nitrogen (N), % not less than 3 6+/-1 not less than 3
Water content, %, not more 2 2 2
Mass fraction of  sulphates in terms of S, % 7-10 8-10 8-10
Mass fraction of calcium in terms of СаО, % 11-14 12-17 12-17
Granularity:
less than 1 mm, % 4 4 5
from 1 до 4 mm, % 85 85 80
less than 6 mm, % 100 100 100
Static strength of granules, MPa (kgs/cm2), not less 3(30) 3(30) 3(30)
Friability, % 100 100 100
Mass fraction of heavy metals and toxic compounds, %, not more
Pb 0,002 0,002 0,002
Cd 0,0001 0,0001 0,0001
Hg 0,00002 0,00002 0,00002
As 0,0004 0,0004 0,0004
Ni 0,002 0,002 0,002
Sr 0,5 0,5 0,5
Cr total 0,003 0,003 0,003

Double superphosphate has several effects on plants simultaneously: it increases the yield and metabolism, significantly accelerates the development of crops and their flowering, enhances the growth of the root system, and improves the quality of the future crop.

This fertilizer is also used to prevent diseases of plants during growth. Double superphosphate has a high content of assimilable phosphorus and doesn’t contain gypsum.