JPS6167726A - Method for collecting valued metals from iron dust including highly zinc - Google Patents

Abstract

PURPOSE:To collect easily a valued metal by low energy by dissolving and deoxidizing a molten iron dust including highly zinc with a carbonaceous solid reducing agent, and separating zinc, iron and lead respectively after the iron dust including highly zinc is granulated and dried. CONSTITUTION:An iron dust including highly zinc D recollected from an electric oven is granulated by a granulating machine 1 in pellet, sent to a drying preheater 2 to remove water content and the reduced quantity due to strong heating and an amount of solid carbon in the pellet is removed by burning. This pellet is sent to a low frequency induction furnace 3 with a coke C dried by a dryer 14, each oxide of iron, zinc and lead is deoxidated and molted, and the residual metallic oxide is mostly slag Sl. The deoxidized iron is discharged as a molten iron Fe from a induction furnace 3 to take out a slag Sl from an exhaust port. The deoxidized lead Pb is gravity-separated from a molten iron and pulled out as a pig lead through a lead bank 4. The deoxidized zinc Zn is molten, evaporated and led to a zinc condensor 5 together with the deoxidated gas CO and cooled to remove impurity and collected through a cooling tub as a pig zinc.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for recovering valuable metals such as zinc and iron from high-zinc iron-containing dust generated, for example, in electric furnace steelmaking.

<Prior art and its problems> For example, dust generated in an electric furnace is collected by a dust collector, but the amount of dust is usually 6 to 5% of crude steel, and its composition is 25 to 30% iron, Zinc 20-2
Although it contains a large amount of valuable metals, such as lead 3 and 4, there is no simple recovery method on a small scale.
Currently, it is handed over to specific smelting manufacturers for centralized processing.

As such recovery methods, the lorry kiln-blast furnace method and recently a 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. .

This invention was proposed in view of the above-mentioned current situation, and its purpose is to provide a method for recovering valuable metals that can easily recover valuable metals from high zinc-containing iron costs with low processing energy. .

<Means for Solving the Problems> The method for recovering valuable metals according to the present invention is to granulate high-zinc iron-containing dust into pellets, and charge the pellets at high temperature in a drying/preheating process to remove the amount of metal in the dust. After removing the ignition loss valve (hydroxides, carbonates, chlorides, etc. that vaporize at high temperatures) and actively burning off the fixed carbon content in the tast, it is put into an induction furnace together with a carbonaceous reducing agent. The zinc is then melted and reduced in an induction furnace and separated by distillation to produce crude zinc.
Iron and lead are separated by specific gravity so that iron can be recovered as molten pig iron and lead can be recovered as crude lead easily and 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 granulated into pellets with a size of 6 to 15 mm in a granulator 1.

The granulated pellets are sent to the shaft type dryer/preheater 2, where they are dried and preheated with charging gas at 800 to 1000'C, and after removing moisture in the second part of the furnace, they are heated to a high temperature in the lower part of the furnace. While moving to the belt, the ignition loss valve is removed, and the fixed carbon content in the pellets is further burned off. Here, the combustion of fixed carbon will be used to preheat the pellets, and there is no loss of energy.

These pellets are fed into a low frequency induction furnace B along with coke C dried by the coke dryer 14, where iron oxides, zinc oxides, and lead oxides are reduced and melted, and most of the remaining metal oxides are turned into slag. Form S1.

The reduced iron is discharged from the induction furnace 6 as molten pig iron (approximately 4% 0) Fe, and hot-charged to the subsequent electric furnace.

The generated slag is either extracted with the hot metal while stirring while the induction furnace is energized, or the slag is left to stand temporarily with the energization turned off, and then discharged from a separate outlet 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 in specific gravity, accumulates in a lead reservoir 4 in the lower part of the furnace, and is periodically extracted as crude lead.

Reduced zinc Zn has a relatively low boiling point, so it cannot be melted or
The molten zinc is evaporated and introduced into the zinc condenser 5 in a gaseous state together with the reducing gas 00, cooled by the molten zinc circulated by the zinc circulation pump 7, condensed as a liquid, and cooled in the cooling tank 6.
After removing impurities, it is recovered as crude zinc.

The reducing gas CO exiting the condenser 5 exchanges heat with combustion air in a heat exchanger 8, and then is sent to a gas holder 12 via a dust collector 9, a chlorine removal device 10, and a desulfurization device 11, and a portion of it is converted into pellets. The fuel is sent to the combustion furnace 16 as fuel for drying and preheating.

Further, the air heat exchanged with the heat exchanger 8 is also sent to the combustion furnace 16 and used for combustion of the reducing gas CO.

Furthermore, the exhaust gas from the dryer/preheater 2 is transferred to the coke dryer 1.
4 and used for drying the coke, it is then discharged to the outside of the system via a dust collector 15.

<Effects of the Invention> As described above, according to the present invention, high-zinc iron-containing dust is granulated, and the ignition loss valve in the pellets is removed by high-temperature charging gas in the drying/preheating process, and the ignition loss valve is actively After burning off the fixed carbon content in the pellets, they are melted and reduced in an induction furnace. Zinc is separated by distillation to produce crude zinc, iron and lead are separated by specific gravity, iron is converted to molten pig iron, and lead is converted to crude lead. This method has the following effects.

(1) Induction furnaces have a large stirring force and are easy to make the furnace body have an airtight structure.
It is suitable for reduction and distillation of zinc, and valuable metals can be easily recovered.

(li l By removing the ignition loss valve in advance,
When pellets are charged into molten metal in a furnace, bursting does not occur, stable operation of the molten metal is possible, and dust generation can be suppressed.

By pre-combusting the carbon content of the pellets, the pellets can be preheated, and the carbon needed to reduce the pellets as a reducing agent is not supplied from the carbonaceous material present in the pellets, the so-called inner charcoal. , the reduction of metal oxides in the pellets occurs only on the pellet surface, since the carbon is supplied from the hot metal in the furnace. Therefore, Perez i.
It is possible to prevent the sudden generation of gas that occurs when the metal is suddenly exposed to high temperatures and the accompanying destruction of the pellets, and it is possible to suppress the bumping of the molten metal and the generation of dust.

(1v) If the iron content is recovered as hot metal and hot-charged to the subsequent electric furnace, the sensible heat of the hot metal can be effectively used.

(■) In addition to exchanging heat with the combustion air to generate the high-temperature gas necessary for drying and preheating the pellets, the exhaust gas from the induction furnace is used as fuel, etc. outside the system. Coupled with (1), valuable metals can be recovered with low processing energy.

[Brief explanation of drawings]

The drawing is a flowchart of an apparatus for implementing the method for recovering valuable metals according to the present invention. 1. Granulator, 2. Drying/preheater, filter, induction furnace, 4
... Lead reservoir, 5. Zinc condenser, 6. Cooling equipment, 7. Zinc circulation pump, 8. Heat exchanger, 9. Dust collector, 10.
- Chlorine removal equipment, 11... Desulfurization equipment, 12... Gas holder, 13... Combustion furnace, 14... Coke dryer, 15
・Dust collector, D.・High zinc iron tast, C.・Coke, S-certified.・Slak, Fθ.・ Molten pig iron, Zn.・ Molten zinc, Pl)・・ Molten lead, G.・Exhaust gas, A. ··air.

Claims (1)

[Claims] (1) After granulating high-zinc iron-containing dust into pellets, drying and preheating the pellets to remove the ignition loss in the dust, and actively burning and removing the fixed carbon content in the dust, It is put into an induction furnace together with a carbonaceous solid reducing agent, and melted and reduced in the induction furnace. Zinc is separated by distillation and recovered as crude zinc, iron and lead are separated by specific gravity, iron is converted into molten pig iron, and lead is A method for recovering valuable metals from high zinc-containing iron dust, which is characterized by recovering crude lead.