Sliding nozzle filler

Details Sliding nozzle filler Sliding nozzle filler

1998-04-07

2000-04-18

Marcheschi, Michael

Compositions: ceramic

Ceramic compositions

Refractory

501132, C04B 3512, C04B 35105, B22D 4146

Patent

active

060515147

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a filler for a sliding gate, in particular, a filler for a sliding gate which is not melted, sintered or penetrated by molten metal (molten steel) poured into a ladle in a steel works and therefore is easily discharged to let the molten metal through the gate.
2. Description of Related Art
A ladle receiving molten steel in a steel works is provided with a sliding gate. The ladle with the sliding gate is required to be fed with a filler comprising refractory powder before molten steel is introduced into the ladle, for the purpose of preventing the molten steel from solidifying in the gate.
Conventional fillers, however, sometimes form a sintered layer due to molten steel and block the opening of the gate. Since such blocking prevents the molten steel poured in the ladle from being discharged, workers often have to, for example, pound the filler block with iron rods. Such a work is extremely dangerous and, in view of inhibiting labor accidents, it is highly demanded that the possibility that the blocking does not occur (hereafter referred to as non-blocking ratio) should be brought close to 100%.
In addition, in today's prevailing manufacture facilities for continuous casting, the blocking generated in gates cause a lot of problems in operation. In some cases, after being primarily smelted in a converter, steel is secondarily smelted for deoxygenation, dephosphorization or desulfurization in a ladle for a long time. Certain kinds of steel are held in the ladle in a molten state for as long as about 7 to 8 hours. Therefore, there is demand for a filler for sliding gates capable of withstanding such conditions.
As a filler, silica sand is conventionally used. However, in view of resistance to fire, sand obtained by subjecting refractory natural chrome ore to drying and classification (hereafter referred to as chromite sand) is sometimes used as a filler.
Since the chromite sand tends to sinter and cause the blocking at the casting of molten steel, however, the chromite sand is rarely used independently as a filler. In general, as described in Japanese Patent Publication No. Sho 60(1985)-57942, the chromite sand is disposed to form a lower layer in a sliding gate and the silica sand is disposed to form an upper layer therein.
However, when the silica sand and chromite sand are used in complete separation as described in the above Patent Publication, they sometimes cause the blocking in the sliding gate, which leads to an unsatisfactory non-blocking ratio.


SUMMARY OF THE INVENTION

The inventors of the present invention have been making devoted study, finally find out that a desirable non-blocking ratio is achieved with a filler comprising, in a specific blending ratio, powders of different specific gravities which have specific particle size distributions, in which the powders are thereby uniformly mixed.
It is generally known that the chromite sand (the true specific gravity thereof ranging from 4.4 to 4.6, the bulk specific gravity thereof ranging from 2.7 to 2.9) has about twice as great specific gravities as those of the silica sand (the true specific gravity thereof ranging from 2.2 to 2.3, the bulk specific gravity thereof ranging from 1.4 to 1.6). One of the characteristics of the present invention lies in that, by controlling the silica sand and the chromite sand which have different specific gravities so that the particle diameter of the chromite sand, which has the greater specific gravities, is larger than the diameter of a void defined among particles of the silica sand, which has the smaller specific gravities, the silica sand and the chromite sand are not separated by the difference in the specific gravities and are uniformly mixed.
Accordingly, the present invention provides a filler for a sliding gate containing 70 to 90 wt % of chromite sand and 10 to 30 wt % of silica sand in which the particle size distribution is substantially from 500 to 1,000 .mu.m.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sch

REFERENCES:
patent: 4525463 (1985-06-01), Dislich et al.
patent: 4928931 (1990-05-01), Dislich et al.
patent: 5124285 (1992-06-01), Dislich
patent: 5374593 (1994-12-01), Heard et al.
Microstructural and morphological changes of silica and chromite packing sands for sliding gate system for steel ladies after heating at temperature--H.C. Pan and Y.C. Ko--Ironmaking and Steelmaking 1992 vol. 19 No. 5 (no month).

Affiliated with

Also associated with

Rating

Sliding nozzle filler does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Sliding nozzle filler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sliding nozzle filler will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2336162