Identification of the Major Constituents of Fused Potassium Silicate Fertilizer

Abstract

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.KEY WORDS: steel-making slag; fused potassium silicate fertilizer; slow-release; single phase compound; potassium calcium silicate.

K4CaSi6O15—Solving a 90‐year‐old riddle

“…On the Accepted Article other hand, the ternary system is also important for the interpretation of the properties and manufacturing of technical, as well as ancient glasses [17][18][19][20] . Furthermore, detailed knowledge concerning the solid-state characteristics of the existing crystalline compounds occurring in the system K 2 O-CaO-SiO 2 is of essence for the identification of these phases in technical products 16,[21][22][23] . Likewise, the results from experimental phase analytical studies represent an indispensable input for any kind of thermodynamic modelling including database development for slag relevant oxides [24][25][26][27] .…”

“…[17][18][19][20] Furthermore, detailed knowledge concerning the solid-state characteristics of the existing crystalline compounds occurring in the system K 2 O-CaO-SiO 2 is of the essence for the identification of these phases in technical products. 16,[21][22][23] Likewise, the results from experimental phase analytical studies represent an indispensable input for any kind of thermodynamic modeling including database development for slag-relevant oxides. [24][25][26][27] In the course of our ongoing project to unravel the number of crystalline phases in the system K 2 O-CaO-SiO 2 , we found evidence that the so-called 2:1:6 phase (K 4 CaSi 6 O 15 ) reported by Morey et al 1 may, indeed, represent a valid and relevant composition for an existing potassium calcium silicate.…”

Phase equilibria and liquid phase behavior of the K2O-CaO-SiO2 system for entrained flow biomass gasification

“…In fluidized bed combustion of biomass, the formation of K-Ca-silicates layers on the sand particles can lead to agglomeration of the bed [12]. The system is also important component in the potassium silicate fertilizer because the slow rate release of potassium ion to the soil can minimize the carry-over of the chemicals from the farming field to the surrounding environment [13]. Therefore, the data on this system is vital for process optimizations in many industries to make their practices more beneficial and sustainable to meet the strict environment regulations nowadays.…”

Selective leaching of scandium and yttrium from red mud induced by hydrothermal treatment

“…The dissolution of iron mineral goethite was the one that contributed to 24% Fe leaching. The detection K 2 Ca 2 Si 2 O 7 crystal phase can be attributed to the re‐crystallization of dissolved Ca 2+ and Si 4+ in the presence of anion excess 27 …”