Effect of Lime Particle Size on Melting Behavior of Lime-containing Flux

Abstract

By use of an infrared-ray vacuum furnace, effect of CaO particle size on melting behavior of lime-containing flux is studied in the present work. Two kinds of CaO particles of the average diameters of 10 mm and 75 mm are used. Four kinds of lime-containing fluxes are employed, which are CaO-SiO 2 , CaO-FeO, CaO-SiO 2 -Al 2 O 3 as ironmaking slag and CaO-SiO 2 -FeO as steelmaking slag.The relationships of reaction products, heating temperature and holding time are obtained for the fluxes of CaO-SiO 2 and CaO-FeO under the present experimental conditions. As for the flux melting, decreasing the lime particle size can shorten the holding time, but can not decrease the heating temperature. In the melting process of CaO-SiO 2 , a layer of 2CaO · SiO 2 is observed on the periphery of CaO particle, which tends to inhibit the melting of CaO particles. Decreasing the CaO particle size can also effectively promote the dissolution of CaO particles into both kinds of slag of CaO-SiO 2 -Al 2 O 3 and CaO-SiO 2 -FeO.KEY WORDS: lime-containing flux; melting; dissolution of lime; slag formation; particle size of lime.MnO x , FeO x , and TiO 2 into Al 2 O 3 -CaO-SiO 2 slag increased the dissolution rate of lime into slag, while addition of SiO 2 had an opposite effect. 15) In the present work, by use of infrared-ray vacuum furnace, effect of lime particle size on melting behavior of lime-containing flux is studied. Four kinds of fluxes are employed, which are CaO-SiO 2 , CaO-FeO, CaO-SiO 2 -Al 2 O 3 as ironmaking slag and CaO-SiO 2 -FeO as steelmaking slag. The used two different sizes of CaO particles have the average diameters of 10 and 75 mm. For the different kinds of fluxes, the relationships of reaction products, heating temperature and holding time are obtained from analysis results of XRD patterns. The status of flux melting is observed with a scanning electron microscope (SEM) and is analyzed with an energy dispersive spectrometer (EDS). Figure 1 shows the morphologies of all kinds of materials before formation of pellets. Calcium oxide particles of the small size, which were the commercial reagent packed with Ar gas, were relatively uniform in diameter, having the average diameter of 10 mm with the purity of 99.9 %. Calcium oxide particles of the large size were prepared as rapidly as possible by crushing the calcium oxide blocks of the commercial reagent and being sieved with sieve pores of 50 mm and 100 mm, having the average diameter of 75 mm and the purity of 99.9 %. Silicon oxide powders were very fine in size with the average diameter of only 2.0 mm. ahematite powders had greatly varied diameters and irregular shapes, having the average diameter of 15 mm and purity of 99.5 %. The diameters of aluminium oxide powders were varied, ranging from 20 to 80 mm. The aluminum oxide particles were usually in clusters formed by many fine aluminum oxide powders and the aluminum oxide powders had the purity of 99.9 %. Experimental Apparatus and ProceduresSlag 1 of CaO-SiO 2 -Al 2 O 3 was produced by melting the mixture of CaO,...

Dissolution Behavior of Solid 5CaO&middot;SiO<SUB>2</SUB>&middot;P<SUB>2</SUB>O<SUB>5</SUB> in CaO-SiO<SUB>2</SUB>-FeO<I><SUB>x</SUB></I> Slag

“…A lot of researches [1][2][3][4][5][6][7][8][9][10][11] had been devoted to clarify the microscopic reaction mechanisms in the CaO based multi phase flux as the fundamental study to develop new refining technology. Since many researchers [5][6][7][8][9][10][11][12] had confirmed the existence of P 2 O 5 in 2CaOÁSiO 2 phase as 2CaOÁSiO 2 -3CaOÁP 2 O 5 solid solution or compound in steelmaking slag, it is considered by the researchers that the precipitation of 2CaOÁSiO 2 phase in the CaO based multi phase flux is the necessary condition for the formation of solid P 2 O 5 rich phase.…”

Condensation of P2O5 at the Interface between 2CaO·SiO2 and CaO–SiO2–FeOx–P2O5 Slag

“…The dissolution rate was also found to vary with different additives such as CaF 2 , CaCl 2 , Al 2 O 3 and B 2 O 3 2) and the size of CaO particle. 3) Formation of 2CaO · SiO 2 layer on the surface of CaO particles was ascertained by many observations, 4,5) and the dissolution of CaO proceeded by migration of molten slag through cracks on the layers of 2CaO · SiO 2 . The effect of 2CaO · SiO 2 on CaO dissolution and dephosphorization should be confirmed to promote the utilization efficiency of CaO in hot metal dephosphorization process.…”

Dissolution Behavior of Lime into Steelmaking Slag

“…The formation of dicalcium silicate layer was reported by many researchers according to experiments under the static condition. [20][21][22] In the study of Kawai et al, the formation of a dicalcium silicate layer on the surface of the CaO rod was also observed, but they concluded the formation of this layer was not the rate-controlling step.…”