Effect of Oxide Additives on Desulfurization Efficiency of Hot Metal by CaO-based Powders

Shimoda, Isao; Sato, Takashi; Nakasuga, Takamitsu; Nakashima, Kouichi; Mori, Ken-ichiro

doi:10.2355/tetsutohagane1955.90.6_401

Cited by 9 publications

(3 citation statements)

References 5 publications

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“…Many studies have been carried out to evaluate the effects of various additives for desulfurization. [7][8][9] Hot metal desulfurization processes using Mg-containing wire addition [10][11][12] or metallic Mg injection [13][14][15][16] were developed in actual plants. Hot metal desulfurization with Mgbased flux proceeds with gaseous Mg and causes lower temperature drop in the hot metal.…”

Section: Introductionmentioning

confidence: 99%

Hot Metal Desulfurization Behavior with Dolomite Flux

Nakai¹,

Kikuchi²,

Miki³

et al. 2013

ISIJ Int.

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Hot metal desulfurization behavior with dolomite flux was examined in heat treatment tests of pellets and in small-scale and commercial-scale hot metal desulfurization tests by mechanical stirring. In the heat treatment tests of pellets, the Mg gas generation ratio at 1 673 K increased as the CaO/MgO ratio increased. The Mg gas generation ratio reached 90% with dolomite, which was 1.4 times higher than that with CaO + MgO at the same CaO/MgO. With calcined dolomite and Al ash, CaO efficiency for hot metal desulfurization at 1 673 K was 20-30%, which was around double the results with CaO + MgO and CaO. In the desulfurization slag, sulfur was concentrated not with Mg, but Ca and Al were found in an EPMA analysis and detected as CaS by X-ray diffraction. Desulfurization with calcined dolomite and Al ash is considered to proceed by ① desulfurization by Mg(g) and fixing of MgS as CaS, and ② desulfurization by CaO with Mg de-oxidation. 200 t commercial-scale hot metal desulfurization tests with mechanical stirring were carried out. The obtained Mg efficiency for desulfurization was in the range of 15-25% with Mg consumption of 1-1.3 kg/t as MgO. These results were within the same trend as in other studies using metallic Mg and MgO with Al.

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Section: Introductionmentioning

confidence: 99%

Hot Metal Desulfurization Behavior with Dolomite Flux

Nakai¹,

Kikuchi²,

Miki³

et al. 2013

ISIJ Int.

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“…The most suitable composition for dephosphorization was (38-45)CaO- 5) to gain the maximum rate of desulfurization of hot metal. Shimoda et al 6) proposed that CaO-Al 2 O 3 -TiO 2 flux had the greatly promoting effect on desulfurization of hot metal, due to its low melting point and low viscosity. Furthermore, Lee et al 7) developed a new flux of burnt lime(CaO) coated with di-calcium ferrite (2CaO · FeO).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2007

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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,...

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“…Tone et al 19) performed the desulfurization of molten steel using CaO-SiO 2 -Al 2 O 3 -MgO slag by dispersing solid CaO particles and reported that the desulfurization rate decreased with an increase in the volume fraction of the solid particles to 20-30%. Moreover, Shimoda et al 20) conducted a hot metal experiment by adding various oxides to solid CaO and reported that the CaO-Al 2 O 3 -TiO 2 system is effective for desulfurization. Takahashi et al 21) performed desulfurization using solid CaO and liquid slag and reported that the composition of the reaction phase generated on the surface of the solid CaO affected the desulfurization rate.…”

Section: Effects Of Liquid Fraction On Reaction Rate Of Molten Steel ...mentioning

confidence: 99%