JPS5834051A - Classification of dust - Google Patents

Abstract

PURPOSE:To decrease the zinc amount contained in a coarse particulate substance after classification to a half as compared to the conventional mixing and stirring treatment, by subjecting a dust slurry to ultrasonic treatment prior to classify the same by a liquid cyclone to easily exfoliate fine particulate zinc fixedly adhered to the coarse particulate substance. CONSTITUTION:In dezincification of dust in a shaft furnace, an ultrasonic oscillator is provided to a slurry piping connected to the supply side of a liquid cyclone and a shaft furnace dust slurry is treated ultrasonically to exfoliate fine particulate oxide of a low b.p. metal such as zinc fixedly adhered to the surface of the coarse particulate substance in dust. The ultrasonically treated dust slurry in passed through the liquid cyclone to be classified therein and the coarse particulate substance with a reduced zinc content is recovered as an ion source from the underflow side thereof and a fine particulate substance enriched with zinc is taken out from the overflow side thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for classifying zinc in dust using a hydrocyclone.

Generally, a liquid cyclone is used to dezincify blast furnace dust. In other words, the coarse particles on the underflow side classified by the hydrocyclone contain less zinc, and the fine particles on the overflow side contain more zinc, and the coarse particles with less zinc are used as the iron source (sintering raw material). It is being collected.

As shown in the chemical composition of blast furnace dust in Table 1, blast furnace dust contains a large amount of carbon and iron, and if it contains less zinc, it becomes a good source of iron (raw material for sintering), making it an effective dezincing method. is expected.

When blast furnace dust was investigated, it was found that most of it was coarse particles originating from the charged raw materials, and a relatively small amount of low melting point metal (zinc) that had been reduced and evaporated in the blast furnace and then reoxidized. ,
It is composed of fine oxides of alkalis, etc.). Therefore, if blast furnace dust is classified as described above,
Zinc will be enriched in the fine particles on the overflow side.

Furthermore, when these particles were investigated in detail, it was found that fine oxide particles of low melting point metals were quite firmly adhered to the surface of the coarse particles.

Therefore, when blast furnace dust is classified using a liquid cyclone for dezincing, a step is required in advance to separate fine particles of zinc etc. stuck to coarse particles. Conventionally, therefore, a method of mixing and stirring the blast furnace dust slurry as shown in FIG. 1 has been adopted, but this method requires a considerable amount of time and has the disadvantage of requiring the installation of a large stirring tank.

This invention was made to improve these drawbacks, and as a result of various studies on methods for separating fine zinc particles stuck to coarse particles, it was found that when dust slurry is treated with ultrasonic waves, fine particles stuck to coarse particles are removed. It was confirmed that the shaped zinc was easily peeled off.

That is, as shown in FIG. 2, the method for classifying dust according to the present invention is characterized in that the slurry of dust is subjected to ultrasonic treatment and then classified through a liquid cyclone.

The blast furnace dust slurry was pre-treated separately by mixing and stirring in a conventional stirring tank and by ultrasonication according to the present invention, and the amount of zinc in the coarse particles obtained by classifying each with a hydrocyclone was determined. The results were analyzed and shown in Table 2.

Blast furnace dust with the components shown in Table 1 was used as the sample, and the classification conditions were exactly the same (feed pressure sO, 95k
q/cd, siphon pressure; O shoulder wHq), and the experiment was repeated three times.

Table 2 The amount of zinc in the coarse particles of the pre-treatment separation, that is, as shown in Table 2, according to the method of this invention, the amount of zinc in the coarse particles is the control over the conventional method, and the amount of zinc in the coarse particles by the treatment of blast furnace dust is The origin of this idea was to reduce the distance between 1++ and the ship to the conventional value in the amount of iron that is charged into the blast furnace.

However, since ultrasonic treatment can be carried out simply by installing an ultrasonic oscillator in the slurry piping on the supply side of the liquid cyclone, a treatment tank such as a stirring tank is not reliable, and additionally, it requires separate processing for stripping and dispersion treatment. It has the advantage of not requiring processing time.

[Brief explanation of the drawing]

Figure 1 is a flow note showing the conventional dust classification method.
FIG. 2 is a flow sheet showing the dust classification method of the present invention.

Claims (1)

[Claims] A dust classification method characterized by subjecting slurry-formed dust to ultrasonic treatment and then classifying it through a liquid cyclone. ,