JPS6220839A - Method for recovering metal from dephosphorization slag - Google Patents

Abstract

PURPOSE:To efficiently recover a high quality metal from a dephosphorization slag by coarsely crushing the slag, sprinkling water on the slag or blowing steam into the slag to preslake CaO, finely crushing the slag with a crusher and separating and recovering metal with a magnet. CONSTITUTION:Slag produced by dephosphorizing molten pig iron with a lime- base flux is coarsely crushed and put in a vessel 1, and CaO in the coarsely crushed dephosphorization slag is converted into Ca(OH)2 by preslaking by sprinkling water on the slag or blowing steam into the slag through a duct 2. The slag is made easy to crack by swelling caused by the conversion. The slag is finely crushed with an impact crusher or the like, and metal in the finely crushed slag is attracted by a magnet, separated and recovered.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a method for introducing hot metal flowing out from a blast furnace into a hot metal ladle (including a torpedo or other container; the same applies hereinafter) in the middle of a tap trough or in a hot metal ladle. In order to recover the metal contained in the slag from the slag generated when the phosphorus contained in the hot metal is removed using a lime-based flux, from the dephosphorization slag. This relates to a method for recovering bullion.

[Prior art and its problems]

Recently, a lime-based flux is supplied to the hot metal in the tap hole or in the hot metal ladle in the middle of the tap hole or in the hot metal ladle for guiding the hot metal flowing out of the blast furnace to the hot metal ladle, and the flux is used to cool the hot metal in the hot metal ladle. The removal of phosphorus is being carried out.

The molten slag produced during the removal of 144-phosphorus contained in such hot metal contains metal. Conventionally, the metal contained in the molten slag has been extracted by cooling the molten slag, pulverizing the agglomerated slag, and adsorbing the metal in the pulverized slag with a magnet.

However, in the above-mentioned method, the separation of the slag and the metal bullion is insufficient, and the quality of the recovered metal bullion is poor.

Furthermore, in Japanese Patent Application Laid-open No. 59-123706, water is poured into the slag stored in a slag pot to cool it, the cooled slag is discharged outdoors and dried, and then the dried slag is A method for recovering bullion by screening, magnetic separation and crushing is disclosed. However, this method is dangerous because it involves pouring water into the slag pot, and has problems such as a complicated process.

[Purpose of the invention]

Therefore, an object of the present invention is to use a lime-based flux to easily and efficiently separate and recover ingots from the slag generated when removing phosphorus from hot metal. The goal is to provide a method for recovering bullion.

[Summary of the invention]

In this invention, slag generated when dephosphorizing hot metal using lime-based flux is crushed, and then water or steam is blown into the crushed slag to prepare CaO in the slag. The slag that has been slaked and then pre-slaked is pulverized by a crusher, and the metal in the slag thus pulverized is attracted to a magnet and separated and recovered.

[Structure of the invention]

Table 1 shows an example of the composition of slag produced when removing phosphorus from hot metal using lime-based Ω flux. As can be seen from Table 1, since slag is mainly composed of free lime, it is so active (unstable) that it expands and disintegrates even when left in the atmosphere.

*A620s, MgO, MnO, T, Fe: 1~
2%** Calculated from chemical composition and mineral phase The above slag was found to contain constituent minerals β-2CaO and SiO□ in a matrix of free lime as a result of microscopic observation.

It has a structure in which Ca5F (PO4) s + Ca F2 is dispersed, and iron is contained in the above slag in the form of fine particles with a size of about 20 μm to flat particles with a size of several poles. has been done.

The slag having the above-mentioned composition is crushed to a particle size of about 5Qmm or less (preferably 1Qmm or less) using, for example, a show crusher.
Coarsely crush the powder to a size of 5 jllX or less.

Next, water is sprinkled so that water is sufficiently distributed over the slag that has been crushed in this way, and if necessary, water vapor is blown into the slag in order to promote the water utilization reaction of the free lime in the slag. As a result, CaO in the slag is pre-slaked and Ca(OH
) z It expands and becomes easily crushed. In addition, the above-mentioned preliminary quenching may be performed only by blowing water vapor without sprinkling water.

The pre-slaked slag is then pulverized, for example, by crushing it with an in/4' cuticle shear rotating at high speed. Therefore, by attracting the metal in this finely pulverized slag with a magnet, the metal can be efficiently recovered.

The following is an example of conditions for efficiently performing preliminary quenching of slag.

Moisture content of slag = 5 to 15 units Amount of water sprinkled or amount of steam blown = 85 to 170 kLi/
/l・Slag temperature: 20' (! or more preferably 60°C
Time: Several hours to one week [Embodiments of the Invention] Example 1 Dephosphorization slag 200A9 coarsely crushed to a particle size of 5Qmx or less was placed in a container 1 as shown in the drawing, and heated through a conduit 2 at 100°C.
of water vapor was blown in at a flow rate of 20 kg/Hr for about 1 hour. In the drawing, 3 is a pressure gauge, 4 is an elongation gauge, and 55 is a net. To this kind of water vapor injection, more pre-slaked steam is supplied: Amount ■0. ', T/Hr
The material was charged into an impact crusher and pulverized at a rotor circumferential speed of 20 m/sec. Next, the metal in the finely pulverized slag was attracted by a magnet to recover the metal. Table 2 shows the recovery rate and quality of the bullion recovered as described above.

Comparative Example 1 Dephosphorization slag 200# coarsely crushed to a particle size of 50 mm or less was charged into an Inno or Tokkura Socha without pre-slaking at a supply rate of 10 T/Hr and a rotor circumferential speed of 40 m/sec. Shattered. Next, the metal in the finely pulverized slag was attracted by a magnet to recover the metal. Table M3 shows the recovery rate and quality of the bullion recovered above.

As is clear from a comparison of Table 2 and Table M3 above, the recovery rate of metal in the case of pre-saturation by the method of the present invention is extremely high.

Table 3 Example 2 800 kg of dephosphorization slag coarsely crushed to a particle size of 25B or less was leveled into a width of 1 m, length of 2 m, and height of 20 mm, and about 140 kfI of water was poured onto the thus leveled dephosphorization slag. After evenly sprinkling with water, it was covered with a vinyl sheet and left for one week to pre-slake. Next, the slag pre-slaked in this way was fed at a supply rate of 10 T/Hr and a rotor circumferential speed of 20 m/sec.
It was charged into an impact crusher and pulverized under the following conditions. Next, the metal in the finely pulverized slag was collected by attracting it with a magnet. Table 4 shows the recovery rate and quality of the bullion recovered as described above.

〔Effect of the invention〕

As described above, according to the present invention, slag can be easily pulverized by pre-dissipation of CaO, so that the metal in the slag can be efficiently separated and recovered by magnetic force. The amount of phosphorus adhering to the base metal is very small and its quality is excellent, resulting in excellent industrial effects.

[Brief explanation of the drawing]

The drawing is a schematic longitudinal sectional view showing an example of a device for pre-saturation. In the drawings: 1... Container 2... Conduit 3... Pressure gauge 4... Flow meter 5... Web application/person Nippon Kokan Co., Ltd.

Claims (1)

[Claims] Slag generated when dephosphorizing hot metal using lime-based flux is crushed, and then water or steam is blown into the crushed slag to pre-slake CaO in the slag, Next, the pre-slaked slag is pulverized by a crusher, and the ingots in the pulverized slag are attracted to a magnet and separated and recovered. Collection method.