KR910000013B1 - Process for recovering valuable metals from an iron dust containing a higher content of zinc - Google Patents

Abstract

None.

Description

Recovery of valuable metals from high zinc-containing iron dust

The figure shows the fluocha art of the apparatus for implementing the valuable metal collection method which concerns on this invention.

* Explanation of symbols for main parts of the drawings

1: granulator 2: dry preheater

3: induction furnace 4: lead wire

5: zinc condenser 6: cooling tube

7: zinc circulation pump 8: heat exchanger

9: dust collector 10: chlorine removal device

11: desulfurization apparatus 12: gas holder

13: combustion furnace 14: combustion furnace

14 coke dryer 15: dust collector

D: High zinc-containing iron dust C: Coke

S1: slug Fe: molten pig iron

Zn: molten zinc Pb: molten lead

G: exhaust gas A: air

The present invention relates to, for example, a method for recovering valuable metals such as zinc and iron from high zinc-containing iron dust generated in steelmaking in an electric furnace. For example, dust generated in an electric furnace is collected by a dust collector, but the amount of dust usually corresponds to 3-5% of crude steel, and its components are 25-30% iron, 20-25% zinc, and lead 3 Although it contains a large amount of valuable metals such as -4%, there is no small and easy recovery method, so it is concentrated on specific refinery makers.

As such a recovery method, a rotary kiln furnace method or a treatment method using plasma heat has recently been proposed, but all have many problems such as high complexity and high processing cost.

The present invention was devised to solve the above-mentioned phenomenon, and an object thereof is to provide a valuable metal recovery method which can recover valuable metals from high zinc-containing iron dust with low processing energy.

The recovery method of valuable metals related to the present invention is made of high-zinc-containing iron dust as pellets, and the pellets are dried and the ignition loss in the dust by hot and high pressure gas in the preheating process (hydroxides, carbonates, chlorides vaporized at high temperature) At the same time, it actively burns and removes the fixed carbon in the dust, and then injects it with the carbon reducing agent and melts and reduces it in the induction furnace.Zinc is separated by type and specific gravity is separated from iron and lead as crude zinc. Therefore, iron is molten pig iron, and lead can be recovered as an assistant and easily recovered with low processing energy.

It will be described according to an embodiment showing the present invention below.

The high-zinc-containing iron dust D recovered in the electric furnace is granulated into pellets of 6-15 mm by a granulator 1. The assembled pellets are sent to the shaft-type drying, preheater (2) to dry preheat by charging gas at 800-1000 ° C, and after the moisture is removed from the upper part of the furnace, the ignition loss is removed while moving to the high temperature of the lower part of the furnace. Then, the fixed carbon powder in the pellet is burned off. Here, fixed carbon combustion is used for preheating the pellets and there is no loss of energy.

The pellets are fed into the low frequency induction furnace 3 together with the coke (C) dried by the coke dryer (14) so that iron oxides, zinc oxides, and lead oxides are reduced and melted, and most of the remaining metal oxides are slugs (Sl). ). The reduced iron is molten pig iron (approximately 4% C) and is discharged from the induction furnace 3 and charged at a high temperature in an electric furnace at a later stage.

The produced slugs are drawn out together with the molten iron under stirring while energizing the induction furnace, or the energization is stopped and temporarily settled and discharged from a separate outlet on the side of the furnace as is usually done in a blast furnace.

Reduced lead (Pb) has a relatively high specific gravity, so it is separated from the molten iron and gravity, and is pulled out as a rough support by the lead (4) at the bottom of the furnace. Since the reduced zinc (Zn) has a relatively low boiling point, it is evaporated by melting and guided to the zinc condenser 5 in a gaseous state together with the reducing gas CO and cooled by molten zinc circulated by the zinc circulation pump 7 as a liquid. After condensation and cooling in the cooling vessel 6 to remove impurities, it is recovered as crude zinc.

The reducing gas CO exiting the condenser 5 is heat-exchanged with combustion air in the heat exchanger 8 and then passes through the dust collector 9, the chlorine removal device 10, and the desulfurization device 11. Is sent to the combustion furnace 13 as a fuel for drying preheating of the pellets.

Moreover, the air heat-exchanged in the heat exchanger 8 is also sent to the combustion furnace 13, and is used for combustion of reducing gas CO.

The exhaust gas of the drying and preheater 2 is guided to the coke dryer 14 and used for drying the coke and then discharged out of the system past the dust collector 15.

As described above, according to the present invention, the high-zinc-containing iron dust is made into particles, and during the drying and preheating process, the high-temperature charged gas is used to remove the ignition loss in the pellet and actively induces the high-low carbon content in the pellet after combustion. By melting and reducing in the furnace, zinc was separated by distillation to make crude zinc, and iron and lead were gravity-separated, iron was molten pig iron, and lead was recovered as crude oil.

(i) The induction furnace has a high agitation power and is easy to make the furnace body hermetic. Therefore, the induction furnace is suitable for melting, reducing, and distilling zinc, and recovering valuable metals easily.

(ii) By eliminating the loss of ignition in advance, when pellets are charged into the furnace molten metal, there is no bursting and stable operation of the molten metal can be suppressed.

(iii) In addition to being able to preheat the pellets by pre-burning the carbon fraction of the pellets, carbon as a reducing agent necessary for the reduction of the pellets is not present in the pellets, but is supplied from molten iron in the furnace rather than from the coal mine. Therefore, the reduction of the metal oxide in the pellet occurs only at the pellet surface. As a result, it is possible to prevent the rapid gas generation and the destruction of the resulting pellets when the pellets having the coal-resistant suddenly receive a high temperature, thereby suppressing the sudden boiling of the molten metal and the generation of dust.

(iv) Iron may be recovered as molten iron and charged at high temperature into the subsequent electric furnace to effectively utilize the sensible heat of the molten iron.

(v) The exhaust gas of the induction furnace is exchanged with the combustion air for generating hot gases necessary for drying and preheating the pellets, and at the same time, most of the reducing gas is used as fuel outside the system. Energy can be recovered with valuable metals.

Claims (1)

The high-zinc-containing iron dust is made into pellets, and the pellets are preheated by drying in a preheater with 800-1000 ° C charged gas to remove the loss of ignition in the dust and actively burn and remove the fixed carbon in the dust. Into the induction furnace together with a vaginal solid reducing agent, which is melted and reduced in the induction furnace, zinc is separated by distillation, recovered as crude zinc, iron and lead are separated by specific gravity, and iron is recovered as molten pig iron, and lead is recovered as crude oil. A valuable metal recovery method from high zinc-containing iron dust, characterized in that.

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