CN1067439C

CN1067439C - Treatment method for high zinc containing iron dust

Info

Publication number: CN1067439C
Application number: CN98103522A
Authority: CN
Inventors: 周渝生; 陈亮; 张美芳; 李峻泰; 王东彦
Original assignee: Baoshan Iron and Steel Co Ltd
Current assignee: Baoshan Iron and Steel Co Ltd
Priority date: 1998-07-31
Filing date: 1998-07-31
Publication date: 2001-06-20
Anticipated expiration: 2018-07-31
Also published as: CN1211629A

Abstract

The present invention relates to a processing method for high-zinc powder dust containing iron. The powder dust comprises the main components (weight): 30 to 75 wt% of iron, 1 to 30 wt% of zinc, 0 to 30 wt% of carbon, 0 to 5 wt% of lead, and 0 to 3 wt% of sulfur. The method comprises the steps: a certain quantity of materials containing carbon are added to the powder dust containing iron to make carbon content reach 15 to 25%; conglomeration is produced with a particle diameter of 5 to 50mm, and put in a container according to 5 to 15 wt% of slag; the glowing red smelting slag is added to the conglomeration, and kept at 1100 to 1600DEGC for 10 to 30 minutes; low-zinc ball iron, slag and high-zinc smoke gas are obtained by the reduction, and the ball iron and the slag are separated; the high-zinc smoke gas is recovered by dust collecting equipment to obtain zinc products containing zinc with the amount of more than 40%, and the recovery rate of iron and zinc in the powder dust can reach more than 90%.

Description

Method for treating high-zinc iron-containing dust

The invention relates to a method for treating iron-containing dust, in particular to a method for recovering iron and zinc from high-zinc iron-containing dust.

At present, 10 kilograms of gas mud which is difficult to recycle and utilize high zinc and 250-550 kilograms of blast furnace slag with the temperature of 1450-1500 ℃ are generated along with each ton of molten iron produced by large and medium-sized blast furnaces (the waste heat is not recycled); converter and electric furnace each ton of steel also accompany about 5 kg of flue gas dust ash containing high zinc which is difficult to process and about 140 kg of steel slag (the waste heat is not recycled), because the zinc content in the high zinc iron-containing dust reaches 0.7-25%, if the high zinc iron-containing dust is used as blast furnace raw material, the high zinc iron-containing dust can cause melting conglomeration in the blast furnace to obstruct production, the high zinc iron-containing dust is not suitable for iron making; blast furnace gas mud, converter secondary ash and electric furnace dust belong to the high-zinc iron-containing dust, and are difficult to treat, occupy a large amount of storage yards and seriously pollute the environment. Meanwhile, because the iron content is very high, a large amount of iron resources are wasted without recycling. Therefore, the recycling of the high-zinc iron-containing dust is a difficult problem which troubles metallurgical enterprises for a long time. The treatment method in the prior art needs special smelting furnace equipment, and realizes the iron-making process by additionally consuming solid, liquid and gaseous fuels to heat the iron-containing raw materials, so that the equipment investment, the operation cost and the energy consumption are very high, and the treatment effect is not ideal.

The invention aims to obtain a method for recovering and treating iron-containing dust with high zinc, which can recover iron and zinc by utilizing steel slag or blast furnace slag and existing equipment, the waste heat of which is not utilized in the prior art, and does not need energy consumption and new equipment investment.

In order to achieve the purpose, the technical solution provided by the invention is as follows:

a method for processing high-zinc iron-containing dust comprises the following main components (by weight): the method comprises the steps of adding a certain carbon-containing material into iron-containing dust to reach the carbon content of 15-25%, preparing the iron-containing dust into lumps with the particle size of 5-50 mm, placing the lumps into a reaction container according to 5-15% of the weight of molten slag, adding red hot smelting molten slag into the lumps, keeping the red hot smelting molten slag at a reaction temperature of over 1100 ℃ for 10-30 minutes, reducing to obtain low-zinc granular iron, slag and high-zinc flue gas, separating the granular iron from the slag, and recycling the high-zinc flue gas by using dust collection equipment to obtain a zinc product with the zinc content of more than 40%.

The iron-containing dust also comprises (by weight): 0-30% of carbon, 0-5% of lead and 0-3% of sulfur

The reaction temperature is 1100-1600℃.

The smelting slag is steel slag, blast furnace slag and other metallurgical slag with the temperature of 1300-1600 ℃.

The reaction vessel is a steel slag pot or a shallow tray.

The present invention is described in further detail below.

The key points of the invention are as follows: adding a certain amount of carbon into high-zinc iron-containing dust powder to prepare lumps with carbon-containing particle sizes of 5-50 mm, laying the lumps in a steel slag tank or a shallow tray in advance, impacting and heating dust mud lumps by using high-temperature red slag in a slag discharging process, heating the lumps to 1200-1600 ℃ by the red slag in a transportation process, and keeping the temperature for 20-30 minutes, so that zinc oxide in the dust mud lumps is volatilized, iron oxide in the dust mud lumps is reduced into low-zinc granular iron to be mixed in the red slag, the low-zinc granular iron is separated from the red slag, and volatilized high-zinc gas can be recovered by dust collection equipment.

The briquette has the particle size of 5-50 mm, is unlimited in shape, has the particle size of less than 5mm, is easy to generate dust and is inconvenient to transport; greater than 50mm affects heat transfer and reaction rate.

The iron-containing dust comprises the following components (by weight): the iron content is 30-75% (the existing form is simple substance Fe, Fe)₃O₄、Fe₂O₃And CaFe₂O₄、FeSiO₃FeS, etc.), zinc 1-30%, carbon 0-30%, lead 0-5%, and sulfur 0-3%.

Adding a certain amount of carbon-containing material to make the carbon content reach 15-25%, according to the carbon and high-valence iron oxide Fe₂O₃Equivalent calculation of reduction in the reaction In, Fe₂O₃The weight ratio of the complete reaction with the C is as follows: fe₂O₃C = 80: 18, since the iron content range of the dust is generally in proportion to pure Fe₂O₃The ore (containing 72 percent of Fe) needs to be low, so the carbon equivalent for reduction can be met when the mixture ratio reaches 15 percent; considering the different reactivity of carbon, a certain proportion can be prepared, so that the carbon content is 15-25%, and the recovery rate of iron above 95% can be met.

The carbonaceous material can utilize a part of the carbon contained in the iron-containing dust, and a part of the iron-containing dust is made into carbonaceous lumps by adopting dust removal dust powder of a coking plant, or coke powder and coal powder, and is dried, the carbonaceous lumps are laid in a steel slag tank in advance according to about 10 percent of the weight of red slag, and the red hot steel slag is added to the lumps during slag discharging; or the slag is laid in a shallow tray in advance, covered and heated by high-temperature slag in a slag tank, and kept at the temperature of over 1100 ℃ for 20-30 minutes to obtain low-zinc granular iron, slag and high-zinc flue gas.

The principle of the invention is as follows: iron oxides in the dust agglomerates undergo the following direct reduction reaction with carbon at high temperatures:

, ,

the generated iron reacts with the red hot carbon to generate the low melting point raw iron particles as follows:

, ，

reducing iron oxide in the dust and mud lumps into low-zinc granular iron to be mixed with the red slag, separating the granular iron from the slag by utilizing the existing steel slag treatment equipment of a steel plant by a hot closed tank method or a roller method, and separating by using a magnetic separation device to obtain the granular iron.

For a blast furnace ironmaking plant without a steelmaking workshop, the high-zinc gas mud can be reduced by utilizing the sensible heat of blast furnace slag, and then the slag is separated from granular iron by a granulated slag granulating system.

The zinc oxide in the dust agglomerate is reduced and volatilized: the zinc volatilizes into gas above 900 ℃, volatilizes along with the smoke dust, and is oxidized into zinc oxide to deposit after entering the air, namely: and recycling high-zinc flue gas by using dust collection equipment to obtain a zinc product containing 40-60% of zinc, wherein the recovery rate of zinc can reach more than 90%, and can reach more than 95% under the condition of excessive carbon.

The granular iron prepared by the method can be used as a waste steel raw material for a converter or an electric furnace, and also can be used as a raw material for an iron melting furnace or a blast furnace, and the recovery rate of iron and zinc in the high-zinc dust can reach more than 90%.

The invention is also suitable for recovering the granular iron products from the waste dust and the pyrite cinder with low cost in other nonferrous smelting plants generating wastes.

The invention does not need to adopt a special reaction device, utilizes the slag afterheat in thecurrent flow of a smelting plant and the existing slag device, converts part of high-zinc dust into granular waste steel, recovers the other part of high-zinc dust from a dust collecting system to obtain a zinc product, does not generate secondary pollution, does not discharge new solid waste and harmful gas, does not need to use additional fuel, greatly saves energy for dust treatment, improves the energy efficiency of a steel plant, and reduces the product cost. Meanwhile, except a small amount of cold mixing and briquetting equipment, other pyrometallurgical equipment is not required to be built, only the existing steel and iron slag recovery and treatment equipment of a steel plant is utilized, and the investment of the equipment is very low.

Embodiments of the present invention are described below.

Example 1

In this example, main dedusting ash was sintered, the components of which are shown in table 1, coke powder was added to the ash and the mixture was pressed into briquettes containing 18 to 20% C, the briquettes were dried and then placed into slag pots (each pot can contain about 33 tons of molten slag), and about 3 tons of the carbon-containing briquettes were placed in advance in the bottom of the pot. In the slag discharging process, 1600 ℃ steel-making slag is uniformly mixed with carbon-containing agglomerates after entering a slag tank, the carbon-containing agglomerates are wrapped and heated, the temperature of molten slag is reduced by about 200-300 ℃, the slag is heated for 20-30 minutes, iron oxide in the dust agglomerates and carbon are subjected to direct reduction reaction to generate low-melting-point pig iron particles, the pig iron particles are melted and contracted to form granular iron and are separated from the molten slag, the granular iron is embedded in solid slag, the slag and the iron are granulated by a hot stuffy tank methodor a roller method, and then a magnetic separation device is used for separating to obtain granular iron products. About 0.45 ton of granular iron can be recovered from each ton of sintering main electric dust, and 0.15 ton of coke powder or coke plant CDQ powder (coke dust recovered from dry quenching flue gas, containing more than 75% of fixed carbon and about 3% of volatile components) is consumed.

Example 2

Oven drying or air drying blast furnace gas mud (containing iron 46.51% and carbon 22.19% in Table 1), adding appropriate amount of binder such as one or more of waste paper pulp liquid, waste syrup, water glass or cement, and pressing into 35 × 25 × 15 oval balls by a pair roller ball pressThe briquette contains 22% of carbon, so that carbon powder is not needed to be added, the briquette is dried and then is added into a slag pot according to the proportion of 10% of the weight of red slag, 1500-1600 ℃ steel slag is flushed into the slag pot during slag discharging, the steel slag is mixed with the briquette and wrapped and heated to 1200 ℃, after 20-30 minutes, the briquette is reduced into granular iron, about 0.42 ton (about 2% of C) of granular iron can be produced per ton of dust, 0.25 ton of slag is produced, and the slag and the steel slag can be used as a paving material after being uniformly blended. TABLE 1

Numbering	Chemical composition (wt%)
	Chemical composition (wt%)						Fe	FeO	Zn	C	Pb	S
	Example 1	48.27	5.62	1.86	4.2	0.57	0.69
Example 2	46.51	2.9	1.6	22.19	0.53	0.41

Claims

1. A treatment method for high-zinc and iron-containing dust. Add certain carbon-containing materials to the iron-containing dust to make agglomerates with a particle size of 5-50mm, and react with red-hot smelting slag. The reaction temperature is above 1100°C Keep it for 10 to 30 minutes, reduce to obtain low-zinc granulated iron, slag and high-zinc flue gas, separate the granulated iron and slag, and recover high-zinc flue gas with dust collection equipment to obtain zinc products with a zinc content greater than 40%. The feature is that the main components of iron-containing dust are (by weight): total iron content 30-75%, zinc 1-30%, after the iron-containing dust is made into agglomerates with a carbon content of 18-25%, according to the weight of slag 9-15% is placed in a reaction vessel, and the red hot smelting slag is added to the agglomerate.

2. The method for treating high-zinc iron-containing dust according to claim 1, characterized in that: the composition of the iron-containing dust also includes (weight): 0-30% carbon, 0-5% lead, 0-3 sulfur %

3. The method for treating high-zinc and iron-containing dust according to claim 1, characterized in that: the reaction temperature is 1100-1600°C.

4. The method for treating high-zinc iron-containing dust according to claim 1, characterized in that: said smelting slag is steel slag, blast furnace slag and other metallurgical slags with a temperature of 1300-1600°C.

5. The method for treating high-zinc and iron-containing dust according to claim 1, characterized in that: the reaction vessel is a steel slag tank or a shallow pan.