The possibility of phosphogypsum application as the element of prefibricated building

Abstract

Phosphogypsum which is produced by "dihydrating procedure" contains not only uncleanesses but radionuclides, too which limit its construction use. Performed testings point to the structure complexility and phosphogypsum composition while the electron microscope’s pictures showed a different crystal phosphogypsum composition comparing to the natural gypsum. In order to use the waste material of phosphogypsum it must be refined and calcined because of a great number of uncleanesses, the soutce of raw-material and because of a chemical way of producing. By expecting procedure of refinery the radionuclides content stays approximately the same, but it approaches to the natural gypsum because of its physico-chemical characteristics. A stable shape of phosphogypsum α-chemihydrate is got by a longer drying on the temperature of 105°C and it is very similar to the natural gypsum because of its physico-chemical characteristics. As the presence of some uncleanesses isn’t limited for the further use, the phosphogypsum refined in this way, by futher particles reducing to the size of ca. 100 μm, shows as adequate substitute for the natural gypsum. The calcined and refined phosphogypsum can be used for partion walls producing. To avoid the danger of possible radionuclides presence it is better to use the mixture of natural gypsum and phosphogypsum for this production. A great saving of materials and economic effect can be carried out in this way.

Fosfogips dobijen "dihidratnim postupkom" sadrži, osim nečistoća, i radionuklide koji ograničavaju njegovu primenu u građevinarstvu. Ispitivanja izvršena u radu ukazala su na složenost strukture i sastava fosfogipsa, dok su snimci na elektronskom mikroskopu pokazali različit kristalni sastav fosfogipsa u poređenju sa prirodnim gipsom. Usled prisustva velikog broja nečistoća koje svoje poreklo vode iz osnovne sirovine (fosfogipsa) i zbog hemijskog načina prerade, da bi se otpadni fosfogips upotrebio mora se dodatno prečišćavati i kalcinisati. Predviđenim postupkom prečišćavanja sadržaj radionuklida ostaje približno isti, ali se po njegovim fizičko-hemijskim svojstvima približava prirodnom gipsu. Dužim sušenjem, na temperaturi od 105°C, dobija se stabilni oblik fosfogipsa, α-hemihidrat, koji je po svojim fizičko-hemijskim karakteristikama veoma sličan prirodnom gipsu. Pošto prisustvo nekih nečistoća nije ograničavajuće za dalju primenu, ovako prečišćen fosfogips, daljim usitnjavanjem čestica do veličine od cca. 100 μm, predstavlja adekvatnu zamenu za prirodni gips. Kalcinisani i prečišćeni fosfogips može se koristiti za izradu gipskartonskih ploča, koje se zatim mogu upotrebiti za izradu pregradnih zidova. Da bi se potpuno uklonila opasnost od eventualno prisutnih radionuklida, za izradu je bolje da se koristi mešavina prirodnog gipsa i fosfogipsa. Na taj način ostvarila bi se velika ušteda u materijalu i veliki ekonomski efekat.