JPH0778259B2 - Recovery method of metal from dephosphorization slag - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to hot metal flowing out of a blast furnace to a hot metal ladle (including torpedo and other containers; the same applies hereinafter) or during tapping gutter or in a hot metal ladle. In, the phosphorus contained in the hot metal, from the slag generated when removing using a lime-based flux, from the dephosphorization slag for recovering the metal contained in the slag It relates to the method of collecting bullion.

[Prior art and its problems]

Recently, in the middle of or in the hot metal ladle for guiding the hot metal flowing out of the blast furnace to the hot metal ladle, in the hot metal ladle, a lime-based flux is supplied to the hot metal in the hot metal ladle or the hot metal ladle, and by the said flux. Phosphorus in hot metal is removed.

Metal is contained in the molten slag generated during the removal of phosphorus contained in such hot metal. The ingot contained in this molten slag is conventionally crushed by cooling the molten slag into lumps, and the ingot in the crushed slag is adsorbed by a magnet. Was there.

However, the above-mentioned method has a problem that the slag and the ingot are not sufficiently separated and the quality of the recovered ingot is poor.

Further, in JP-A-59-123706, water is poured into a slag contained in a slag pan to cool it, and the cooled slag is discharged to the outside to be dried, and then the dried slag is dried. A method of recovering the metal by sieving, magnetic separation and crushing treatment is disclosed. However, this method is problematic in that it involves pouring water into the slag ladle and that the process is complicated.

[Object of the Invention]

Therefore, an object of the present invention is to use a lime-based flux to remove the phosphorus in the hot metal from the slag produced when the phosphorus is removed from the slag to easily and efficiently separate and recover the metal. The purpose is to provide a method of collecting bullion from.

[Outline of Invention]

This invention coarsely crushes the slag produced when performing dephosphorization of hot metal using a lime-based flux, and then sprays water or steam into the crushed slag to reserve CaO in the slag. It is characterized in that the slag that has been soaked and then preliminarily soaked is finely pulverized by a crusher, and the metal in the slag thus finely pulverized is adsorbed by a magnet to be separated and recovered.

[Structure of Invention]

Table 1 is an example of the component composition of the slag produced when phosphorus in the hot metal is removed using a lime-based flux. As can be seen from Table 1, since slag contains free lime as a main component, it is so active (unstable) that it expands and collapses even if left in the atmosphere.

As a result of microscopic observation, the above-mentioned slag is a constituent mineral β-2CaO.SiO ₂ , Ca ₅ F (PO ₄ ) ₃ , C in the matrix of free lime.
It has a structure in which aF ₂ is dispersed, and the iron content is contained in the above slag in a state of being incorporated, from a fine tablet having a size of about 20 μm to a flat tablet having a size of several cm.

The slag having the above-mentioned component composition is roughly crushed by using, for example, a Diyoke crusher so that the particle size thereof becomes about 50 mm or less (preferably 15 mm or less). Then, water is sprayed so that water is sufficiently spread over the slag thus roughly crushed, and steam is blown in if necessary in order to accelerate the hydration reaction of free lime in the slag. As a result, CaO in the slag is pre-sorted to Ca (OH) ₂ and expands and is easily broken. The preliminary slaking may be performed only by blowing steam without sprinkling water.

The slag is then finely crushed by crushing the pre-swaged slag with, for example, an impact crusher rotating at a high speed. Therefore, the metal in the finely pulverized slag is adsorbed by the magnet, so that the metal can be efficiently recovered.

The following is an example of conditions for efficiently performing pre-swapping of slag.

Moisture content of slag: 5 to 15% Amount of sprinkling water or injection of steam: 85 to 170 kg / t-Slag temperature: 20 ° C or higher, preferably 60 ° C or higher Time: several hours to one week [Examples of the invention] Examples 1. 200 kg of dephosphorized slag roughly crushed to a particle size of 50 mm or less was placed in a container 1 as shown in the drawing, and steam at 100 ° C. was blown into the container 1 through a conduit 2 at a flow rate of 20 kg / Hr for about 1 hour. In the drawing, 3 is a pressure gauge, 4 is a flow meter, and 5 is a mesh. The slag preliminarily neutralized by the blowing of water vapor was charged into an impact crusher under the conditions of a supply rate of 10 T / Hr and a rotor peripheral speed of 20 m / sec, and pulverized. Then, the metal in the finely pulverized slag was adsorbed by a magnet to recover the metal. Table 2 shows the recovery rate and quality of the bullion collected above.

Comparative Example 1 200 kg of dephosphorized slag coarsely crushed to a particle size of 50 mm or less was charged into an impact crusher under the conditions of a supply amount of 10 T / Hr and a rotor peripheral speed of 40 m / sec without crushing, and pulverized. . Then, the metal in the finely pulverized slag was adsorbed by a magnet to recover the metal. Table 3 shows the recovery rate and quality of the bullion collected above.

As is clear from the comparison between Tables 2 and 3, the bullion recovery rate is extremely high in the case of preliminary slaking by the method of the present invention.

Example 2 800 kg of dephosphorized slag roughly crushed to a particle size of 25 mm or less is leveled to a width of 1 m, a length of 2 m and a height of 20 cm, and about 140 kg of water is evenly sprayed on the dephosphorized slag thus leveled. After that, it was covered with a vinyl sheet and left for 1 week for preliminary sterilization. Then, the slag thus preliminarily soaked was charged into an impact crusher under the conditions of a supply amount of 10 T / Hr and a rotor peripheral speed of 20 m / sec, and pulverized. Then, the metal in the finely pulverized slag was adsorbed by a magnet to recover the metal.
Table 4 shows the recovery rate and quality of the bullion collected above.

[Effects of the Invention] As described above, according to the present invention, the slag can be easily finely pulverized by the preliminary soaking of CaO, so that the metal in the slag can be efficiently magnetized. It can be separated and recovered, and the amount of phosphorus adhering to the recovered metal is very small and its quality is excellent.

[Brief description of drawings]

The drawing is a schematic vertical cross-sectional view showing an example of an apparatus for preliminary dissociation. In the drawing, 1 ... container, 2 ... conduit, 3 ... pressure gauge, 4 ... flow meter, 5 ... mesh

Claims (1)

[Claims] 1. A slag produced during dephosphorization of hot metal using a lime-based flux is crushed, and then water or steam is blown into the crushed slag to remove CaO in the slag. In the dephosphorization slag, which is characterized by preliminarily slagging and then pulverizing the slag preliminarily slagging with a crusher and adsorbing the metal contained in the slag thus pulverized to a magnet for separation and recovery. How to collect the bullion from.