JPH0155919B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for effectively utilizing high basicity steelmaking slag, which disintegrates during the cooling process and is difficult to handle. There are various types of steelmaking slag, and among these, the present invention targets reduction stage slag of ordinary steel with high basicity, electric furnace slag of special steel, and continuous casting slag. Here, the reduction stage slag of ordinary steel refers to slag discharged during the reduction scouring process when ordinary steel is produced by electric furnace smelting. Currently, these three types of slag are placed in a slag pot for about 80 minutes.
It is discharged after cooling for ~12 hours, approximately 150~200℃
When this happens, the work environment is bad because it causes dusting and disintegrates, and the current situation is that it is disposed of in a landfill after being sprinkled with water to prevent it from scattering. The present invention solves the above-mentioned drawbacks and relates to a method for effectively utilizing the slag in the reduction period of ordinary steel.
A method in which electric furnace slag of special steel or continuous casting slag generated after continuous casting is quenched in air to form β-2CaO/SiO ₂ as the main substance, and then gypsum is added and crushed to be used as a sludge solidification material or soil improvement material. It is. Experiments conducted to confirm the effects of the method of the present invention and their results will be shown below. Table 1 shows the chemical analysis values and properties of the samples used in the experiment. In Table 1 below, reduction stage slag refers to reduction stage slag of ordinary steel, CC slag refers to continuous casting slag,
Electric furnace slag refers to electric furnace slag of special steel, and oxidation stage slag refers to oxidation stage slag of ordinary steel (the same applies hereinafter). In Table 1, reduction stage slag, CC
The main mineral content of slag and electric furnace slag is γ-
Other than 2CaO・SiO _{2 ,} the amount was omitted because the amount was so small that it fell within the background as a result of X-ray diffraction. Next, Table 2 shows the analytical values of the soluble components of each slag.

[Table] 〓
*2 It was set as 100% because it collapsed due to dusting during the cooling process.

[Table] The reducing stage slag, CC slag, and electric furnace slag shown in Table 1 are put into an electro-fused magnesia crucible and remelted, the molten slag flows out from the crucible with a hole in the bottom, and is strongly blown with air. The quenched spherical or elliptical objects were collected in a container. The main mineral content of this rapidly cooled slag is β-
2CaO.SiO ₂ , and the disintegration rate when autoclaved (ASTM) was approximately 1 to 2%. This rapidly cooled slag is mixed with 4 to 7% by weight of gypsum dihydrate and milled in a ball mill to obtain a Blaine value of approximately 2000 to 2500 cm ² /
(hereinafter referred to as quenched pulverized product such as reduction period slag of ordinary steel). For comparison, commercially available ordinary Portland cement, ground blast furnace water slag (44 μm or less, Blaine value 3100 cm ² /g), converter slag tailings (approximately 72% of 0.5 mm or less and 44 μm or less), lime (reagent grade 1) Quicklime) was added to sludge with a moisture content of 50% in the proportions shown in Table 3, mixed with a stirrer, placed in a plastic bag, and the solidification state was examined. The results were as shown in Table 3. The compounding ratio in Table 3 indicates the dry weight%, where ◎ means that it is very hard when pressed by hand, 〇 means that it is the same hardness, △ means that it is slightly hard, and × means that it is not solidified. Each shows that. In addition, quenched crushed slag of common steel was added to the Kanto loam layered soil with a moisture content of 28% in the same manner as described above, mixed in a mortar bowl, and then placed in a soil test mold in three layers with a rammer. Separate and pack (JIS method),
Table 4 shows the results of examining the compressive strength after 10 days of humid air curing (20°C, 60%).

【table】

[Table] * Dusting materials such as slag during the reduction stage of ordinary steel

【table】

[Table] As described above, according to the method of the present invention, by air quenching from a molten state, quenched slag with a mineral composition of β-2CaO・SiO ₂ , non-collapsible, and hydraulic property is formed. Adding gypsum to this can solidify sludge, volcanic ash, etc. in the same way as cement or blast furnace water slag powder, and even with a small amount of addition, stable soil with high compressive strength can be obtained. It has the effect of being Furthermore, in the method of the present invention, when rapidly cooling the molten slag,
Sensible heat can also be recovered and used effectively as hot air, etc.

Claims (1)

[Claims] 1 Reduction stage slag of ordinary steel, electric furnace slag of special steel, or continuous casting slag generated after continuous casting is quenched in air to form β-2CaO/SiO ₂ main components, and then gypsum is added and crushed to form a sludge solidification material. and how to use it as a soil improvement material.