Feed phosphates

Feed phosphates are feed additives (mineral feed) used in the absence of calcium, phosphorus, sodium, and nitrogen in animal diets. These include mono-, monodi-, dicalcium phosphate, disodium phosphate, monoammonium phosphate, diammonium phosphate.

JSC NIUIF has been developing and improving feed phosphate technology since the 2000s to the present and specializes in the processing of prepurified wet-process phosphoric acid (WPA).

Technology of calcium feed phosphates using defluorinated phosphoric acid

Calcium feed phosphate technology (MCP, MDCP, DCP) is based on the neutralization of calcium raw materials previously purified from fluoride evaporated WPA.

The main consumer specifications of MCP and MDCP.

Specification

MCP

MDCP

DCP

1 Mass fraction of Р2О5 soluble in 0.4% hydrochloric acid solution (recalculated to phosphorus), %

51±1
(22±0,5)

47±1
(20,5±0,5)

44±1
(19±0,5)

2 Mass fraction of calcium, %

16±1

19±1

23±1

3 Mass fraction of moisture, %, not more than

4

3

3

4 Mass fraction of fluoride, %, not more than

0,2

0,2

0,2

5 Fraction content 0,2÷2,0 mm, %, not less than

80

90

90


The removal of fluoride from WPA is carried out in the process of its concentration by fire or vacuum evaporation. Depending on the calcium raw materials, the concentration of WPA may vary. In the case of chalk (limestone), the required concentration of WPA (not less than 62% of Р2О5) and the removal of fluoride is achieved with fire evaporation, in the case of lime it is sufficient to evaporate Р2О5 to 54÷56% and remove fluoride in a vacuum cycle.

Mixing of reagents, neutralization of WPA with chalk (lime) and granulation are carried out in dynamic apparatuses: turbo mixers, plow-type mixers and in rotating granulators with internals.

A flexible process line with plow mixer without aging stage, based on neutralization of phosphoric acid with natural chalk or limestone, is intended for the production of mono-, monodi-and dicalcium phosphate.

When neutralizing the 1st hydrogen ion of phosphoric acid, monocalcium phosphate is formed. When two phosphoric hydrogens are replaced by calcium in the process of phosphoric acid neutralization with chalk or limestone, dicalcium phosphate is formed. By neutralizing phosphoric acid with chalk or limestone in excess (125÷175%) in relation to the MCP formation rate (by replacing the 1st acid hydrogen ion by calcium), a mixed product, MDCP, can be obtained. The ratio of mono- and di-forms can vary widely.

The flowsheet is shown in Fig. 1. The clarified WPA, chalk and recycle are fed into the plow mixer. Drying of the product is carried out in a drying drum with inlet dryer gases produced in combustion chamber. The dried product is fed to the preliminary classification, then for cooling in a fluid bed cooler (FBC) and additional classification. The screened product at the stages of preliminary and additional classification is sent to the plow mixer (recycle). Recycle oversize is going through a crushing stage. Exhaust gases after a plow mixer, drying drum, FBC and dedusting system undergo dry and wet scrubbing. Scrubbing feed is done by river water. Scrubber liquid is returned to the plow mixer.

FP.jpg

Figure 1. Flow sheet of MCP, MDCP production with plow mixer

1 - phosphoric acid tank with pump; 2 - chalk, limestone sack-off bin; 3 - recycle sack-off bin; 4 - plow mixer; 5 - DGD; 6 - elevator; 7 - screen; 8 - mill; 9 - FB cooler; 10 - scraper-type conveyer.

Feed phosphate technology with purified phosphoric acid

WPA with high content of magnesium oxides and sesquioxides is poorly subjected to evaporation and defluorination, thus preliminary purification of impurities with organic extractants is required.

WPA pre-purification technology has several advantages:

  • possibility to use WPA with high content of impurities;
  • possibility of obtaining a wide range of feed phosphates: calcium phosphates, ammonium phosphates, sodium phosphates;
  • possibility of obtaining purified commercial phosphoric acid and purifying phosphates from impurities (MAP/DAP/MPP/MCP/SP/STPP) to food grade.
JSC NIUIF specialists can develop technology and instrumentation for feed monocalcium phosphate with a capacity of 100 up to 350 thousand tons of final product per year.