JPS60251234A - Method for recovering valuable metal from iron dust containing high zinc - Google Patents

Abstract

PURPOSE:To obtain crude zinc by means of distillation and separation of zinc and to recover iron and lead by means of specific gravity separation by pelletizing iron dust contg. high lead which is produced in an electric steel making process together with a carbonaceous reducing agent, melting and reducing the pellets. CONSTITUTION:The dust D contg. 25-30% Fe, 20-25% Zn and 3-4% Pb which is produced from an electric steel making factory is mixed with a carbonaceous reducing agent C such as coke and granulated to pellets Pe with a granulator 1. After removing the water from the pellets with a drier 2, these are stored and fed to a preheater 3 to be preheated and fed to a low frequency induction furnace 4 to reduce the oxides of Fe, Zn and Pb respectively. The reduced Fe is taken out as molten iron and desulfurized together with flux Fl in a desulfurizing furnace 5. The reduced Pb is separated from the molten iron by means of specific gravity difference and fed to a forging machine 7 as crude lead. The reduced Zn is evaporated and entered into a zinc condenser 8 together with gaseous CO and intermediately cooled with air A to be condensed as crude zinc for recovery.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention provides a method for recovering valuable metals such as zinc and iron from high-zinc iron-containing dust generated in electric furnace steelmaking.

<Prior art> The dust generated in an electric furnace is collected by a dust collector, but the amount of dust is usually 3 to 5% of crude steel (1) 18, and its composition is 25 to 30% of iron.
Although it contains a large amount of valuable metals, such as 20 to 25 tres of zinc and 5 to 4 tres of lead, it is handed over to a specific smelting manufacturer free of charge because it is small-scale and there is no easy recovery method. is the current situation.

As such recovery methods, the rotary kiln-blast furnace method and the recent treatment method using plasma heat have been proposed, but both have many problems such as the complexity of the treatment process and the high treatment cost. are doing.

<Purpose of the Invention> This invention was proposed in view of the current situation as described above, and its purpose is to provide a method for recovering valuable metals that can easily recover valuable metals from high-zinc iron-containing dust with low processing energy. It is about providing.

<Structure of the Invention> The method for recovering valuable metals according to the present invention involves adding a carbonaceous solid reducing agent (2) such as coke to high-zinc iron-containing dust, granulating it into pellets, and drying and preheating the pellets. After that, it is melted and reduced in an induction furnace, the zinc is separated by distillation and recovered as crude zinc, the iron and lead are separated by specific gravity, and the iron is recovered as molten pig iron and the lead is recovered as crude lead.
This makes it possible to easily recover valuable metals such as zinc and iron from high-zinc iron-containing dust with low processing energy.

<Example> The present invention will be described below based on an illustrative example.

The high-zinc iron-containing dust D recovered from the electric furnace is reduced to 6 to 15 sus in a granulator 1 after a carbonaceous solid reducing agent such as coke 0 is added to reduce it and add the necessary amount of carbon to the pig iron.
The pellets Peζζ are granulated.

Granulated pellets Pa are dried in shaft type @2
After moisture is removed, the water is sent to the storage/preheater 3.

The preheated pellets) Pa are put into a low frequency induction furnace 4, where pig oxides, zinc oxides, and lead oxides are reduced and melted.
The remaining metal oxide mostly forms slag s1.

The reduced iron Fθ is transferred to induction furnace 4 as hot metal (approximately 4% O).
After being desulfurized by flux F1 through a desulfurization device 5 if necessary, it is hot-charged into an electric furnace 6.

The generated slag is extracted from the induction furnace together with the hot metal while it is being energized and stirred, or it is left to stand still temporarily with the energization turned off, and then discharged from separate discharge ports on the furnace side, as is normally done in blast furnaces. .

Since the reduced lead PB has a relatively high specific gravity, it is separated from the hot metal by specific gravity, and the accumulated part at the bottom of the furnace is periodically extracted.
It is sent to the lead casting machine 7 as crude lead.

Reduced zinc Zn has a relatively low boiling point, so it cannot be melted or
Zinc condenser 8 in gaseous state with evaporated and reducing gas 00
- It is guided, condensed as a liquid by indirect cooling with air A, and continuously sent to the zinc casting machine 9, where it is recovered as crude zinc.

The reducing gas 00 that has exited the zinc condenser 8 is further sent to the storage/preheater 3#, where the sensible heat of the preheater for the pellets Pa is utilized, and then sent to the gas holder 10, where part of it is converted into pellets. It is sent to the combustion furnace 11 as a drying fuel.

Furthermore, the air heat-exchanged in the zinc condenser 8 is also sent to the combustion furnace 11 and used as a heat source for burning the reducing gas 00 and drying the pellets.

A portion of the exhaust gas G from the dryer 2 is recycled to the combustion furnace 11, desulfurized by the desulfurizer 12, removed by the dust collector 15, and then discharged to the outside.

<Effects of the Invention> As described above, according to the present invention, a carbonaceous solid reducing agent is added to high zinc-containing iron dust, and after pelletizing, drying, and preheating, it is melted and reduced in an induction furnace, and zinc is separated by distillation. iron and lead are separated by specific gravity, iron is recovered as molten pig iron, and lead is recovered as crude lead.The exhaust gas from the induction furnace is used to dry and preheat the pellets, resulting in the following effects: play.

(1) Induction furnaces have a large stirring power and are easy to make the furnace body have an airtight structure, so they are suitable for melting pellets, reduction, and distilling zinc, and can easily recover valuable metals. can do.

(II) Since the exhaust gas of the induction furnace is effectively used for drying and preheating the pellets, and most of the reduction product gas is used as fuel outside the system, the processing efficiency is lower than in (I). Valuable metals can be recovered using energy.

611) If iron is recovered as hot metal and hot-charged into an electric furnace, the sensible heat of the pig iron can be effectively used.

[Brief explanation of drawings]

The drawing is a flowchart of an apparatus for carrying out the valuable metal recovery method according to this invention number. D...high zinc iron-containing dust, 0...coke, Pa/temperature pellets, Fe...iron, Zrz/zinc, PI).・Lead, 74...Flux, COI/Reducing gas, A.
・Air, 1.. Granulator, 2.. Dryer, 3.. Storage/preheater, 4.. Induction furnace, 5.. Desulfurization equipment, 6.. Electric furnace.
7. Lead casting machine, 8. Zinc condenser, 9. Zinc casting machine, 10. Gas holder, 11. Combustion furnace, 12. Desulfurization equipment, 13. Dust collector. (7)

Claims (1)

[Claims] (1) After adding a carbonaceous solid reducing agent to high-zinc iron-containing dust, it is granulated into pellets. After drying and preheating the pellets, they are melted and reduced in an induction furnace, and the zinc is separated by distillation to form a crude product. A method for recovering valuable metals from high zinc-containing iron dust, which is characterized in that zinc is recovered, iron and lead are separated by specific gravity, iron is recovered as molten pig iron, and lead is recovered as crude lead.