RU2582423C1 - Method of processing of dusty wastes from metallurgical production - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular to a method for processing waste dust from metallurgical production. Proposed method comprises feeding dusty wastes from metallurgical production with carbon material on surface of molten slag in slag receiving bowl after filling with liquid slag of melting unit, heating, reduction of metal oxides and extraction of recovered metals. Layer of dusty wastes is placed between layers of carbon material. Extraction of recovered metals is performed by magnetic separation when processing slag.

EFFECT: use of invention prevents ambient secondary metal oxidation of reduced oxygen and provides clean metallic bars.

2 cl, 1 tbl, 1 ex

Description

The development relates to the field of processing metal-containing wastes of metallurgy and mechanical engineering by extracting metal compounds for return to the metallurgical cycle, and can also be used to obtain additives in composite materials to ensure high biological resistance.

A known method of processing metallurgical waste (dust), in which the briquetting of waste is carried out together with a solid carbon-containing substance in the form of crushed stone or brown coal with a grain size of 3-5 mm Briquettes are fed into a direct-flow tube furnace heated from the fuel loading side by oxygen burners, while the temperature of the briquettes at the furnace outlet is maintained in the range of 700-1000 ° C. Waste before briquetting is preheated in a heating countercurrent tube furnace to a temperature of 550-1000 ° C [RU 2240361, 20.11.2004].

The disadvantage of this method is that the necessary reduction potential for a high degree of iron metallization is not fully formed and the content of metallic iron in the unloaded briquettes is not enough to use them for direct loading into steelmaking units, which reduces the consumer cost of the product.

A known method of processing dust of metallurgical production, including dust agglomeration together with a carbon reducing agent with the addition of material with an MgO content of at least 70%, drying the obtained agglomerated materials, heating and calcining them at a temperature of 1200-1400 ° C together with an additional amount of carbon material, recovering recovered metals by magnetic separation [RU 2450065, 05/10/2012].

The disadvantages of this method are the high energy costs associated with providing high process temperatures.

Closest to the claimed technical solution is a method of processing pulverized materials or mixtures thereof containing compounds of heavy metals, including the preliminary formation of liquid oxide slag with a basicity of 1-1.4, the supply of pulverized materials or mixtures thereof with the addition of, for example, coal, sand and / or bauxite to or in a bath of liquid metal and liquid oxide slag with the release of volatile compounds of heavy metals into the gas phase and subsequent release from the gas phase, and alkali metal compounds are converted to ox dnye slags [RU 2239662, 10.11.2004].

The disadvantage of this method is the high energy consumption during the formation of liquid oxide slag and the difficulty of supplying pulverulent material under or onto the liquid slag layer with a special pneumatic conveying unit or using hot blast.

The problem to which the invention is directed is to reduce energy consumption when obtaining a product with iron content of more than 90% from dusty waste from metallurgical production due to the use of heat from the molten slag after being drained into the slag receptacle from the smelter and increasing the degree of reduction of metal oxides. Such a product can be used in steelmaking instead of part of scrap metal or in blast furnaces as an iron-containing additive, as well as for the production of composite building materials with high biological resistance.

The problem is solved as follows.

In the method for processing pulverized wastes of metallurgical production, including the supply of pulverized wastes of metallurgical production with carbon material to the surface of liquid slag, heating, reduction of metal oxides and their extraction, according to the proposed solution, the supply of pulverized wastes of metallurgical production and carbon material is carried out in layers on the surface of liquid slag in slag receiving bowl after filling it with liquid slag from the smelter, while the layer of dusty waste is The metallurgical production is placed between the layers of carbon material, and the recovery of the reduced metals is carried out by magnetic separation during the subsequent processing of slag.

For processing pulverized wastes of metallurgical production by the claimed method, metallurgical dust can be used, in particular, gas cleaning dust from electric arc steel-smelting furnaces (EDSP) containing iron oxides (45-50%) and heavy metals - zinc, nickel, chromium, copper, etc. the chemical composition of the EDSP dust is shown in table 1.

The consumption of crushed carbon material is determined by the amount of iron oxides contained in the initial pulverized waste of metallurgical production according to the material balance of the reduction reactions

Due to imperfect contact between materials, the possibility of direct interaction between carbon and solid oxides is limited. Therefore, direct reduction reactions proceed predominantly with the participation of the gas phase and are the result of the sequential course of indirect reduction reactions

and interactions of carbon dioxide with carbon

The conditions for the occurrence of reduction reactions are ensured by the thermal energy of the slag melt after discharge from the smelter with a temperature of 1600-1650 ° C. The use of carbon material only in an amount calculated according to reaction equation (1) does not allow to obtain a high degree of reduction of metal oxides in connection with the secondary oxidation of the reduced metals with ambient oxygen.

To avoid secondary oxidation of the reduced metals, a layer of pulverized waste from metallurgical production is placed between the layers of carbon material. Carbon of the solid material of the layer located on the surface of liquid slag is gasified with carbon dioxide by reaction (3) and the carbon monoxide formed under the created pressure penetrates into the layer of processed pulverized waste, ensuring the reduction of oxides by reaction (2). A layer of carbon material located above the layer of recyclable material prevents the penetration of atmospheric air by accelerating the oxidation (burning) of oxygen in the air and eliminates the secondary oxidation of reduced metals.

The absence of oxygen both in the depth of the material layer and on its surface is a guarantee of preservation of the reduced metals in the calcined material discharged from the furnace.

As the carbon material, crushed coke, coal, anthracite, and the like can be used. fineness 1 ÷ 3 mm. If the particle size is less than 1 mm, the porosity of the layer and the permeability of the reducing gas will decrease. When the particle size of the reducing agent is more than 3 mm, the dust will penetrate into the carbon layer, which can lead to slagging of the reduced metals.

An example implementation of the claimed method.

According to equation (1), for processing 1 ton of gas cleaning dust (the average chemical composition of the dust is presented in Table 1), 115 kg of carbon material is required. The amount of additional carbon material located above the layer of the processed substance, it is advisable to take equal to the amount of coal in the first layer. Thus, the height of the layer of additional carbon material with a bowl diameter of 250 cm will be 10 cm.

Carbon material with a size of 1-3 mm in the amount of 115 kg is loaded onto the bottom of the tipping or opening container bottom. The next layer is formed from recyclable dust (the chemical composition of the dust is shown in Table 1) in an amount of 1 ton. The same carbon material in an amount of 115 kg is poured on top. Thus, when tipping the bucket onto the surface of liquid slag, the layers will be arranged in the same order. The total mass of the material is selected from the condition of decreasing the temperature of the slag melt from 1600-1650 ° C to 1400 ° C.

Due to the heat of the slag melt, the temperature of the layers rises to 1350-1400 ° C, and metals are reduced by reactions (1, 2, 3). Extraction of reduced metals is carried out by magnetic separation during the subsequent processing of slag according to known technologies.

Claims (2)

1. A method of processing pulverized wastes of metallurgical production, including feeding pulverized wastes of metallurgical production with carbon material to the surface of the slag melt, heating them with heat of molten slag, reducing metal oxides and recovering reduced metals, characterized in that the supply of pulverized wastes of metallurgical production and carbon material layer by layer on the surface of the slag melt into the slag receiving bowl after filling it with the slag melt from the smelter That, while the layer of pulverized waste from metallurgical production is located between the layers of carbon material, and the recovery of reduced metals is carried out by magnetic separation during the subsequent processing of slag. 2. The method according to p. 1, characterized in that the crushed coke, coal and anthracite with a particle size of 1 ÷ 3 mm are used as the carbon material.