Identification of the Major Constituents of Fused Potassium Silicate Fertilizer

摘要

The major component of fused potassium silicate (FPS) fertilizers, produced from steel-making slag, was studied. FPS compounds have received considerable attention as slow-release potassium fertilizers beneficial for crops. This major component was found to be a single phase compound, K_(2)Ca_(2)Si_(2)O_(7), which had not been previously identified. In order to confirm the presence of the newly identified compound, we synthesized a potassium calcium silicate mixture, K_(2)O–2CaO–2SiO_(2), by fusing a mixture of K_(2)CO_(3), CaCO_(3), and SiO_(2). The X-ray diffraction patterns of the synthesized K_(2)O–2CaO–2SiO_(2) were largely consistent with those of FPS fertilizer, and Energy Dispersive X-ray Spectroscopy indicated that this compound was a single phase with a K:Ca:Si molar ratio of 1:1:1. It is concluded that the major component of FPS fertilizer is a compound of K_(2)O–2CaO–2SiO_(2), newly identified as K_(2)Ca_(2)Si_(2)O_(7). FPS fertilizers exhibit the characteristic, controlled by their K_(2)Ca_(2)Si_(2)O_(7) content, of slowly releasing potassium into water and soil.