STUDY OF THE CHEMICAL AND MINERALOGICAL COMPOSITION OF THE COMPLEX-MIXED FERTILIZERS OBTAINED ON THE BASIS OF VERMICULITE AND SELECTION OF THE OPTIMAL COMPOSITION

Аннотация

This paper investigates the possibility of obtaining multicomponent complex mixed fertilizers based on local mineral raw materials—Karakalpakstan vermiculite—and fertilizer salts (ammophos and urea). The vermiculite content in the fertilizer was varied at 40, 50, and 60%, while the ratio of nutrient components was adjusted within the range of N: P₂O₅= 2:1 to 1:2 to synthesize 15 distinct samples using a pan (disc) granulator. The chemical composition, pH, granulometric distribution, and mechanical strength of the resulting granules were systematically evaluated. Based on a comprehensive evaluation of agrochemical and physico-mechanical properties, sample No. 4 was selected as the optimal composition. This sample—containing 40% vermiculite at an ammophos:urea mass ratio of 42.67 : 17.33 (N:P₂O₅ = 1:1.5)—exhibits a high total P₂O₅ content (17.392%), the highest total CaO content (8.978%), maximum granule mechanical strength (3.2 MPa), and a high yield of the commercially demanded 2–4 mm fraction (73%). SEM-EDS characterization of the optimal sample confirmed that the material retains its original vermiculite Mg–Al–Si matrix while being successfully modified with essential nutrient components (N, P, K).