ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Identification of the Major Constituents of Fused Potassium Silicate Fertilizer
Yasuko YaoEtsuo HamadaKaoru SatoTakashi AkiyamaTadakatsu Yoneyama
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2014 Volume 54 Issue 4 Pages 990-993


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, K2Ca2Si2O7, which had not been previously identified. In order to confirm the presence of the newly identified compound, we synthesized a potassium calcium silicate mixture, K2O–2CaO–2SiO2, by fusing a mixture of K2CO3, CaCO3, and SiO2. The X-ray diffraction patterns of the synthesized K2O–2CaO–2SiO2 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 K2O–2CaO–2SiO2, newly identified as K2Ca2Si2O7. FPS fertilizers exhibit the characteristic, controlled by their K2Ca2Si2O7 content, of slowly releasing potassium into water and soil.

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© 2014 by The Iron and Steel Institute of Japan
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