JPH06136458A - Method for recovering resources from waste - Google Patents

Abstract

PURPOSE:To efficiently separate and recover Fe and Zn as the chlorides at a low temp. and at a high reaction rate by treating a blast furnace dust contg. the oxide grains of Fe, Zn, etc., with a Cl-CO base gas. CONSTITUTION:A blast furnace dust 1 contg. the powders of iron oxides, zinc oxide, etc., is charged into a circulation-type fluidized furnace 3 along with a spent plastics contg. Cl and if necessary, CaCl2 and heated to a relatively low temp. of 800-850 deg.C. The gaseous Cl, CO, etc., generated by the thermal decomposition of the spent plastics 2 are allowed to react with the grains of the iron oxide and zinc oxide to convert the Fe and Zn to their chlorides. The ZnCl2 having a low b.p. is gasified and introduced into a cyclone 4 along with the solid FeCl2. The gaseous ZnCl2 is separated from FeCl2, introduced into a cooling chamber 5, rapidly cooled to 300-350 deg.C, solidified and recovered by a bag filter as the ZnCl2 grain which is used as the material for Zn. The FeCl2 grain is hydrolyzed in the cyclone 4 by the moisture in the atmosphere to form Fe2O3 which is returned to the furnace 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a low melting point metal component from a waste containing an oxide of a high melting point metal such as iron and a low melting point metal oxide such as zinc and lead generated in a blast furnace dust. The present invention relates to a method for separating and recovering.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a flow of a conventional method for separating iron / iron oxide and zinc from blast furnace dust generated from an iron mill. Blast furnace dust 1 and blast furnace char or coke 1
2 is supplied into the circulating fluidized furnace 3 maintained at about 1000 ° C. in a reducing atmosphere to reduce zinc oxide and produce zinc. Since the boiling point of zinc is about 900 ° C, it becomes gaseous and is sent to the cyclone 4 together with the exhaust gas, separating the solid particles such as zinc oxide and iron oxide that have not been reduced yet, and the gas component is sent to the gas cooling chamber 5. Then, the zinc and a part of zinc oxide 8 which have been rapidly cooled to about 300 ° C. with the cooling water 7 are separated from the exhaust gas 11 by the bag filter 6 and collected.
The solid particles separated by the cyclone 4 are returned to the circulating fluidized furnace 3 via the circulation line 10. The zinc and a part of zinc oxide thus recovered are raw materials for zinc production.

Iron oxide is partially reduced in the circulating fluidized furnace 3. At the above temperature, iron and iron oxide exist as solids, and even if they are entrained in the exhaust gas, they are captured by the cyclone 4 and are circulated. It is returned to the circulating fluidized furnace 3 via 10. The dust having a high iron or iron oxide content, which is recovered as a solid from the bottom of the circulating fluidized furnace 3 or the circulation line 10, can be used as a raw material for sintering.

[0004]

In the above method, since zinc oxide is reduced to zinc and vaporized, it is necessary to maintain the inside of the circulating fluidized furnace at 930 ° C. or higher, which is the boiling point of zinc. 100 facilities such as cyclone and circulation line
A large amount of auxiliary energy is required to maintain the temperature at about 0 ° C. Further, reduction of zinc oxide is a reaction between solid carbon and carbon monoxide. Since the reaction between zinc oxide and solid carbon is a solid-solid reaction, the reaction time becomes longer and The furnace needed to be raised to save time.

Therefore, the present invention solves the above problems and converts the low melting point metal compound in the waste into a substance that is easily vaporized at a low temperature, and separates it from a solid such as a high melting point metal oxide to make it a resource. The present invention aims to provide a method for efficiently recovering.

[0006]

The present invention is a method for separating and recovering a high melting point metal component and a low melting point metal component from a waste containing a large amount of a high melting point metal oxide and a small amount of a low melting point metal oxide. In the above, in the above waste, waste plastic containing chlorine and or calcium chloride is added and reacted under a reducing atmosphere, and the low melting point metal is separated into chloride gas,
It is a method of recovering resources from waste, which is characterized by cooling and recovering.

[0007]

The present invention is a reducing gas such as chlorine and carbon monoxide generated by thermal decomposition of waste plastic containing chlorine such as vinyl chloride in a reaction furnace such as a circulating fluidized furnace, which is low in the waste. It separates the melting point metal oxide into chloride gas, cools it, and collects it. Compared with the conventional method that separates it as vapor of low melting point metal, it separates and collects the low melting point metal component efficiently at low temperature. You can

Taking blast furnace dust containing zinc oxide and iron oxide as an example, zinc chloride has a boiling point of 730 ° C., whereas zinc has a boiling point of 930 ° C. In the method of the present invention, the temperature of the reaction furnace is considerably increased. Can be lowered. The form in which zinc oxide is reacted with zinc chloride is mainly a solid-gas reaction, whereas the reduction reaction of zinc oxide is a solid-solid reaction and a part solid-gas reaction. You can speed up the time. The iron component reacts with chlorine to form iron chloride, but it is not hydrolyzed by the water contained in the reaction gas to iron oxide and hydrogen chloride, so it does not move to the gas side like zinc chloride. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a flow of a process for recovering resources from waste, which is an embodiment of the present invention.
Blast furnace dust 1 which mainly contains zinc as a low melting point metal and iron as a high melting point metal, chlorine-containing waste plastic 2, calcium chloride as needed, and the proportion of chlorine are equivalent ratio x (2
~ 3) is adjusted and charged into the circulating fluidized furnace 3.
The inside of the furnace 3 is about 800 to 850 ° C. under normal pressure, the velocity of particles is 4 to 6 m / sec, and a reducing atmosphere (air ratio of 0.6 to 0.
8) is secured, and at the same time as the charging, the evaporation of water from the blast furnace dust and the thermal decomposition of the waste plastic 2 occur. By reacting with a reducing gas such as chlorine or carbon monoxide generated by this thermal decomposition, zinc chloride is vaporized. Zinc chloride gas is introduced into a high temperature collector such as a cyclone 4 together with the exhaust gas, and after separating solid particles, it is guided to a gas cooling chamber 5 and rapidly cooled to about 300 to 350 ° C. with cooling water 7 and solidified chlorination. Zinc is collected by a trapping device such as a bag filter 6.

The iron in the blast furnace dust 1 is hydrolyzed by the water in the exhaust gas into an oxide even if it becomes a chloride in the circulating fluidized furnace 3 and is captured by the cyclone 4 and passed through the circulation line 10 again. It is returned to the circulating fluidized furnace 3. Also,
The zinc oxide that has not been converted to chloride has a sublimation temperature of 1720 ° C under normal pressure of zinc oxide, so even if it is entrained in the exhaust gas, it is captured by the cyclone 4 as a solid and circulates like iron oxide. It is returned to the flow furnace 3. Since such a reaction is repeated in the circulating flow furnace 3, the amount of zinc compound contained in the iron oxide dust 9 extracted from the lower part of the furnace is 1
It can be reduced to 0% or less. Since the exhaust gas 11 exhausted from the bag filter 6 contains unburned gas, it is recombusted, treated with exhaust gas, and then released to the atmosphere.

[0011]

According to the present invention, since the low melting point metal is separated as chloride gas by adopting the above configuration, the temperature in the circulating fluidized furnace is higher than that in the conventional case where it is separated as low melting point metal vapor. It can be greatly reduced and energy can be saved. Further, in the case of the present invention, the solid-gas reaction is the main component, compared to the conventional blast furnace dust and blast furnace char, and the solid-solid reaction and solid-gas reaction utilizing carbon monoxide after the primary reaction. It is possible to increase the separation efficiency of the like.

[Brief description of drawings]

FIG. 1 is a diagram showing a flow of a resource recovery process from waste, which is an embodiment of the present invention.

FIG. 2 is a diagram showing a flow of a conventional resource recovery process from waste.

Claims (1)

[Claims] 1. A method for separating and recovering a high melting point metal component and a low melting point metal component from a waste containing a large amount of a high melting point metal oxide and a small amount of a low melting point metal oxide. A method for recovering resources from wastes, characterized in that waste plastics containing and / or calcium chloride are added and reacted under a reducing atmosphere to separate the low melting point metal into chloride gas, which is then cooled and recovered. .