New Low-Temperature Technology of Producing Calcium Feed Phosphate with Microelements
DOI : 10.3844/ajabssp.2007.248.253
American Journal of Agricultural and Biological Sciences
Volume 2, Issue 4
The possibility of producing feed calcium phosphates in a way ensuring a low physical water content in the product was investigated in laboratory conditions. For this purpose the process use of a phosphoric acid solution with a higher (than in conventional methods) P2O5 content (53-63% by wt. P2O5) with CaO (molar fraction of 0.5-0.8) and CaCO3 in the phosphoric acid neutralizing mixture was tested. Phosphates with a high content of phosphorous forms highly assimilable by animals, soluble in 0.4% HCl (94-99%), were obtained. The physical water content of 1-4% by wt. H2O was obtained when a phosphoric acid solution with a 59% by wt. P2O5 content and a CaO molar fraction of 0.8 in the neutralizing mixture were used and for a phosphoric acid solution with a 63 % by wt. P2O5 content. A temperature above 160°C was obtained when respectively phosphoric acid with a 59% by wt. P2O5 content and the highest CaO fraction in the neutralizing mixture and a phosphoric acid solution with a 63% by wt. P2O5 content were used. An elevated CO2 content in the products, indicating an increase in the unreacted calcium carbonate content, was found when a phosphoric acid solution containing 59% by wt. P2O5 and a CaO fraction of 0.8 in the neutralizing mixture were used and also for a phosphoric acid solution with a 63% by wt. P2O5 content and a CaO fraction of 0.7-0.8 in the neutralizing mixture. By supplementing extraction phosphorous acid composition with microelements (Se, Cu and Zn compounds) at the stage of extraction phosphoric acid production one can obtain a product with a homogenous content of the elements, but this entails losses as high as 70-80% caused by the separation of phosphogypsum from the phosphorous material decomposition product. Because of the different mass fractions of microelement salts and feed phosphates a homogenous selenium compound content in feed phosphate is obtained only after 8 hours of mixing. Mixing time is twice shorter for copper and zinc.
© 2007 Józef Hoffmann. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.