GB2122180A - Packing sand for steel ladles - Google Patents

Abstract

A packing sand for molten steel vessels (particularly steel ladles with sliding gate systems) consists of a high purity silica sand and a potassium feldspar. Preferably the composition of the sand is 85-98 weight % SiO2 and 1.0-3.0 weight % K2O+Na2O while the particle size can vary from 0.4-2.5 mm. The sand provides a superior resistance to entry of molten steel while not hindering flow of the steel after opening the exit.

Description

SPECIFICATION Packing sand for steel ladles This invention relates to packing sand for a steel ladle.

In the manufacture of steel, a packing sand is used to fill an exit opening in a vessel before admitting molten steel to that vessel. The presence of the sand in the exit opening prevents steel solidifying in the exit. Thus in the sliding gate system at the base of a steel ladle, the exit well is filled with refractory sand called packing sand before filling the ladle with molten steel. The presence of the sand prevents steel from solidifying in the well. In the absence of the sand, solidified steel block the flow of liquid steel through the well from the ladle.

Sands hitherto used have not been sufficiently refractory to resist the most effect of molten steel and cause blockages and other undesirable effects in such exit openings.

According to the present invention there is provided a packing sand which comprises a high purity silica sand and a potassium feldspar.

Preferably, the composition of the sand is, in weight percent, 85-98 SiO2 and 1.0-3.0 K2O+Na20. Preferably the particle size of the sand is from 0.4 to 2.5 mm. Most suitably the K20 content of the feldspar will exceed 12% by weight of the feldspar.

In the accompanying drawings: Figure 1 illustrates a sliding gate system for a steel ladle containing packing sand prior to admission of molten steel to the ladle; Figure 2 illustrates the system immediately after filling with molten steel; Figure 3 illustrates the situation at the time of opening the sliding gate.

Figure 1, is illustrated a typical sliding gate system for a molten steel ladle. In the floor 11 of the ladle, there is an opening through which passes vertically an upper nozzle 2 which is surrounded by a well block 1. At the lower end of the upper nozzle 2, there is an upper plate 3 against which there is slidably engaged a lower plate 4 in which is mounted a lower nozzle 5. In the closed position, the lower plate 4 seals the opening in the upper plate 3 to which the upper nozzle 2 leads and the lower nozzle 5 is distanced from said opening of the.upper nozzle. In the open position as illustrated in Figure 3, the lower nozzle 5 and upper nozzle 2 are in communication, the upper plate 3 having been moved to locate the lower nozzle in the desired position.

Thus in Figure 1, the sliding gate system is shown in the closed position with the well block and upper nozzle 2 leading to the gate filled with sand 6. As shown in Figure 2, after admission of molten steel, there is an upper layer 7 of molten feldspar mixed with solid silica beneath which is an intermediate layer 8 of partially used feldspar together with solid silica above a layer of unfused packing sand 9. The layer of molten feldspar prevents the penetration of liquid steel into the packing sand while the intermediate layer is not so thick as to interfere with the flow properties of the total mass of sand.As shown in Figure 3, when the gate is opened the unmelted and unfused sand in the lower portion of the mass is able to flow out of the well and permits immediate flow of the steel 10 which flow of the steel is not interfered with by the molten and fuse portions of the sand. The layers of molten and fused feldspar collapse under the weight of molten steel 10 as illustrated in Figure 3.

Silica sand used in the composition of the invention must be purified to move low meltingpoint substances and can be processed, for example, by ore dressing to eliminate these substances. The closer to a pure silica the better the sand for this purpose. The feldspar used should be one which contains a K20 content of 1 2% by weight or greater. The amount of feldspar added to the silica sand will be determined by the desired K2O+Na2O weight % which is desired and which is chosen in relation to the size distribution of the particles and the purity of the silica sand.

Obviously to avoid caking in the well, it is desirable the sand be as dry as possible and customarily any moisture will be removed by drying before use in the well. In particular, the packing sand will usually be dried and packaged in a sealed bag of an appropriate amount for each individual use. The sand is stored under conditions which will avoid any segragation of the components of the sand prior to use.

Packing sands according to the invention have been extensively tested in field tests and pilot runs and proved to be very satisfactory in filling the wells of steel ladles and yet not hindering the release of steel from the ladle on opening the sliding gate.

Claims

1. A packing sand for the exit of a molten steel vessel comprising a high purity silica sand and a potassium feldspar.

2. A packing sand according to Claim 1, in which contains 85-98 weight % SiO2 and 1.03.0 weight % K20+Na2O.

3. A packing sand according to either Claims 1 or 2, in which the particle size is from 0.4-2.5 mm.

4. A packing sand according to any one of Claims 1 to 3, in which the K20 content of the feldspar is at least 1 2% by weight of feldspar.

5. A packing sand according to any one of Claims 1 to 4, substantially as hereinbefore described.

6. A method of handling molten steel in which an exit opening for a container for the seel is filled with a packing sand prior to admission of steel to the container, which packing sand is a sand according to any one of Claims 1 to 5.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Packing sand for steel ladles This invention relates to packing sand for a steel ladle. In the manufacture of steel, a packing sand is used to fill an exit opening in a vessel before admitting molten steel to that vessel. The presence of the sand in the exit opening prevents steel solidifying in the exit. Thus in the sliding gate system at the base of a steel ladle, the exit well is filled with refractory sand called packing sand before filling the ladle with molten steel. The presence of the sand prevents steel from solidifying in the well. In the absence of the sand, solidified steel block the flow of liquid steel through the well from the ladle. Sands hitherto used have not been sufficiently refractory to resist the most effect of molten steel and cause blockages and other undesirable effects in such exit openings. According to the present invention there is provided a packing sand which comprises a high purity silica sand and a potassium feldspar. Preferably, the composition of the sand is, in weight percent, 85-98 SiO2 and 1.0-3.0 K2O+Na20. Preferably the particle size of the sand is from 0.4 to 2.5 mm. Most suitably the K20 content of the feldspar will exceed 12% by weight of the feldspar. In the accompanying drawings: Figure 1 illustrates a sliding gate system for a steel ladle containing packing sand prior to admission of molten steel to the ladle; Figure 2 illustrates the system immediately after filling with molten steel; Figure 3 illustrates the situation at the time of opening the sliding gate. Figure 1, is illustrated a typical sliding gate system for a molten steel ladle. In the floor 11 of the ladle, there is an opening through which passes vertically an upper nozzle 2 which is surrounded by a well block 1. At the lower end of the upper nozzle 2, there is an upper plate 3 against which there is slidably engaged a lower plate 4 in which is mounted a lower nozzle 5. In the closed position, the lower plate 4 seals the opening in the upper plate 3 to which the upper nozzle 2 leads and the lower nozzle 5 is distanced from said opening of the.upper nozzle. In the open position as illustrated in Figure 3, the lower nozzle 5 and upper nozzle 2 are in communication, the upper plate 3 having been moved to locate the lower nozzle in the desired position. Thus in Figure 1, the sliding gate system is shown in the closed position with the well block and upper nozzle 2 leading to the gate filled with sand 6. As shown in Figure 2, after admission of molten steel, there is an upper layer 7 of molten feldspar mixed with solid silica beneath which is an intermediate layer 8 of partially used feldspar together with solid silica above a layer of unfused packing sand 9. The layer of molten feldspar prevents the penetration of liquid steel into the packing sand while the intermediate layer is not so thick as to interfere with the flow properties of the total mass of sand.As shown in Figure 3, when the gate is opened the unmelted and unfused sand in the lower portion of the mass is able to flow out of the well and permits immediate flow of the steel 10 which flow of the steel is not interfered with by the molten and fuse portions of the sand. The layers of molten and fused feldspar collapse under the weight of molten steel 10 as illustrated in Figure 3. Silica sand used in the composition of the invention must be purified to move low meltingpoint substances and can be processed, for example, by ore dressing to eliminate these substances. The closer to a pure silica the better the sand for this purpose. The feldspar used should be one which contains a K20 content of 1 2% by weight or greater. The amount of feldspar added to the silica sand will be determined by the desired K2O+Na2O weight % which is desired and which is chosen in relation to the size distribution of the particles and the purity of the silica sand. Obviously to avoid caking in the well, it is desirable the sand be as dry as possible and customarily any moisture will be removed by drying before use in the well. In particular, the packing sand will usually be dried and packaged in a sealed bag of an appropriate amount for each individual use. The sand is stored under conditions which will avoid any segragation of the components of the sand prior to use. Packing sands according to the invention have been extensively tested in field tests and pilot runs and proved to be very satisfactory in filling the wells of steel ladles and yet not hindering the release of steel from the ladle on opening the sliding gate. Claims

1. A packing sand for the exit of a molten steel vessel comprising a high purity silica sand and a potassium feldspar.

2. A packing sand according to Claim 1, in which contains 85-98 weight % SiO2 and 1.03.0 weight % K20+Na2O.

3. A packing sand according to either Claims 1 or 2, in which the particle size is from 0.4-2.5 mm.

4. A packing sand according to any one of Claims 1 to 3, in which the K20 content of the feldspar is at least 1 2% by weight of feldspar.

5. A packing sand according to any one of Claims 1 to 4, substantially as hereinbefore described.

6. A method of handling molten steel in which an exit opening for a container for the seel is filled with a packing sand prior to admission of steel to the container, which packing sand is a sand according to any one of Claims 1 to 5.