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  • Author or Editor: I. Dombalov x
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Summary The free energy of the acidic ammonium sulfate is a good precondition it’s use as an additive or reagent for decomposition of natural phosphates on the way to obtain NPS or NPKS complex fertilizers. During our previous studies it was confirmed that as a result of thermo-mechanical treatment new solid phases are formed as a result of the phosphates decomposition. The aim of this study is to find out appropriate conditions for thermal treatment of Tunisia phosphorite with ammonium sulfate where the content of P2O5 soluble forms has its maximum. The process was investigated under dynamic thermal conditions. Structure and phase transformations of the mixtures to intermediate and final solid products are confirmed by different techniques. X-ray powder diffraction, infrared spectroscopy and electron microscopy have been applied successfully and relationship found between phase structure and thermal treatment applied. As a result of the complex studies optimal temperatures are determined. The solid products under optimal conditions contain phosphorous in soluble forms available for plants in the soil. As a final it is concluded that the final products could be used as complex mineral fertilizers.

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Summary No data is available in the literature about the effects of mechano-chemical activation on the processes of chemical interaction in the Tunisia phosphorite-ammonium sulphate mixture. The purpose of this paper is to study the chemical and thermal reactions in mixtures of Tunisia phosphorite and ammonium sulphate in a mass ratio of 1:1, triboactivated in a planetary mill using different mill balls for a period of 10 h. Using chemical, thermal, X-ray powder diffraction and infrared spectroscopy to analyse the activation products, and analysing the changes occurring during the TG-DTA-DTG measurements, allowed to determine the chemical transformations in the system and to assess the degree of transformation of non-soluble forms of phosphorus from the natural phosphate into soluble. Data from the studies have registered the changes in the solids resulting form preliminary mechano-chemical activation of samples. The additional endo- and exothermic effects resulting from thermal decomposition in the temperature range of up to 1373 K are proof of the changes during the TG-DTA-DTG studies and of new interactions occurring in the system. The results from the thermal and spectroscopic methods show that triboactivation using different mill balls and modes of operation produce new compounds in the form of ortho-, pyro- and tripolyphosphates, soluble in the soil solution. The data obtained are part of the complex studies on the way to optimize the composition and conditions of triboactivation and subsequent thermal treatment aimed to produce high-efficiency slow-acting fertilizer products.

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