SU1756362A1 - Process for reduction roasting of siderite ore in shaft furnace - Google Patents

Abstract

Essence: the process of calcining siderite ores in shaft furnaces involves heating, non-oxidizing roasting to obtain a product with a reduction degree to pO2 - 20% and re-reduction to pO2 with 90-95% gas mixture containing reduction to p02 - 90-95% gas mixture containing a reducing agent (H2 + CO) and methane. Dovosstanovlenie lead in two stages: at the beginning of the ore is reduced in countercurrent up to 50-55%, adding to the reducing gas the products of incomplete combustion of natural gas combusted with an excess air coefficient a-0.4-0.42, and then finally recovering the reducing gas into mode pr motoka. In this case, the gas involved in the re-reduction at the first stage is used in the process of burning the ore by after-burning it in the layer with air supplied through the peak burners at two levels along the height of the burning zone with flow rates corresponding to a- 0.7-0.8 and a 1.7-1.9 at the lower and upper levels x, respectively. 1 il.

Description

The invention relates to methods for preparing iron ore raw materials for metallurgical processing and can be used during the process of calcining siderite ore.

The aim of the invention is to reduce fuel consumption and increase the metallurgical value of the finished product.

The goal is achieved by the fact that according to the firing aid of siderite ore in a shaft furnace, including its heating, non-oxidizing firing to produce a product with a degree of oxygen reduction up to 20% and re-reduction with a mixture of gases containing reductants (H2, CO) and methane, re-reduction leads in two stages: first, the ore is reduced in opposition to a pO of 50 ... 55%. adding to the reducing gas that has passed from the lower metallization zone, products of incomplete combustion of natural gas combusted from 0.40 ... 0.42, and then the final re-reduction is carried out with a reducing gas in the metallization zone in the prime mode, and the gas participating in the ore reduction process in the first stage, in the process of burning the ore by the afterburning of gas in the layer with air supplied through the peak burners at two levels along the height of the burning zone with a = 0.7 ... 0.8 at the bottom level and with a 1.7. ..1.9 at the top level.

Separating the re-reduction process into two stages will allow it to be carried out without using special conversion equipment to produce a reducing gas, since recovery of higher iron oxides, not requiring high

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reduction potential occurs in the upper zone due to a mixture of reducing gas in the lower zone and products of incomplete combustion, containing 35 ... 40% H2. 15..20% CO. 2 ... 5% CH4. S5 ... 40% N2, 2 ... 5% NaO and SOA.

Full utilization of chemical heat of gas due to its afterburning in the upper zone will significantly reduce the overall fuel consumption.

The final before the recovery, carried out in the metallization zone reducing gas with a content of 30 ... 35%

CH4 and 60 ... 65% WITH + Н2, WILL ALLOW to increase

metallurgical value of the finished product.

The processes of heating, firing, and refining in the first stage are carried out in a countercurrent mode of gas and material. An antipoint flow pattern in thermal terms is most advantageous, since it provides minimal heat loss with flue gases. For the second stage of the recovery process, a flow pattern of gas and material flows is proposed and, if there is a flow of a part of the reducing gas into the upper zone, it will be possible to eliminate the flow of natural gas into the final reduction cycle with a lower reduction potential of the combustion products of natural gas. Recovery with minimal fuel consumption.

The flow of a part of the reducing gas from the final reduction cycle when mixed with the products of incomplete combustion of natural gas in a ratio of 1: (3 ... 4} significantly increases the reduction potential of the mixture.

The drawing shows a diagram of the technical implementation of the method of recovery firing of siderite ore in a shaft furnace.

The diagram shows a shaft furnace 1 with a cyclone burner 2 for producing products of incomplete combustion of natural gas, dry gas cleaning apparatuses (filters) 3, regenerative air heaters 4, waste heat boilers for hot and circulating gas 5, scrubber-cooler 6, Venturi tube 7 , air-cooled apparatus 8, air heater 9, compressor 10, mixer 11, regenerative gas heaters 12, peak burners 13.

The method is carried out as follows.

In the upper part of the shaft furnace 1, the siderite ore is heated to a temperature

five

950 ° C, burned and restored to the degree of reduction pQ2 - 50 ... 55%. The firing process is carried out in the atmosphere of products of afterburning of the gas entering

from the pre-recovery area. Air is supplied through peak burners 13, located on two levels along the height of the burning zone: In the lower part of the zone, afterburning is conducted from a- 0.7 ... 0.8, and in the upper part

with a 1.7 .... 1.9. In the process of non-oxidizing roasting, a product with po2 of 20% is obtained. Next, the burned ore is reduced to a degree of reduction of rho2 50 ... 55% with a mixture of gases produced in the cyclone burner 2 and coming from the metallization zone of the shaft furnace in the ratio (3 .., 4); 1. Natural gas in a cyclone burner 2 is burned with a coefficient of flow rate of 0.4 to 0.42. The air before it enters the burner is heated to 700 ° C in regenerative air heaters 4.

The processes of heating, burning and partially reducing siderite ore in the upper part of the shaft furnace are carried out in a countercurrent of gas and material. The flue gas is removed from the furnace with a temperature of 400 ... 500 ° C, enters the waste-heat boiler 5, passes through dry gas cleaning filters 3 and

0 is discharged into the chimney.

Preheated to 950 ° С and 50 ... 55% of siderit ore restored to pO2 through the separation zone enters the metallization zone, where

5 flow of the material and gas containing 60 ... 65% of reducing agents (CO + H2) and 30 ... 35% of methane, is carried out its final re-reduction to (pO2 90.,. 95%. Consumption of hydrogen for the metallization process

0 in the zone is compensated for the thermally catalytic decomposition of natural gas on the surface of the heated and partially metallized ore. Metallic iron, formed in the process of restoring,

5 is an active catalyst for the decomposition of natural gas.

The gas from the metallization and cooling zone with a temperature of 600-650 ° C enters the gas-tube waste heat boiler 5, then into the ber-cooler 6, where it is cooled and the dust content decreases. A deeper cleaning of the circulating gas from dust is carried out in the Venturi tube 7. The cleared dust from the circulating gas enters the air-cooled apparatus 8, then into the drip catcher 9 and is compressed by the compressor 10. Next, part of the gas is directed to the cooling zone of the shaft furnace, the other part of the gas mixed with natural gas in mixer 11 and returned to the zone

metallization shaft furnace. To provide the required temperature conditions for the metallization zone, the reducing gas is fed into regenerative gas heaters 12 to 850 ° C before being fed into the furnace. In this case, the amount of heat from cooling the material from 950 ° C to 680 ° C is sufficient to conduct endothermic reactions to reduce iron oxide and decompose natural gas,

In the lower part of the shaft furnace (cooling zone), the metallized product is cooled from 680 to 50 ° C in countercurrent by supplying clean circulating gas to the zone of purified and cooled.

A cold metallized product with a content of 1.4 ... 1.5% of carbon is discharged from the furnace and fed to the briquette section. Briquetting virtually eliminates the possibility of secondary description and significantly improves the transportability of the finished product. Due to the significant content of magnesium oxide (up to 17–20%), metalized siderite ore briquettes can be used as natural material in the blast furnace and converter production.

The proposed method of burning siderite ore reduces natural gas consumption by 10% compared to the known, and the increase in the final reduction rate from 84 ... 87% to 90 ... 95% improves the metallurgical value of the finished product.

Claims (1)

Claims The method of reductive roasting of siderite ore in a shaft furnace, including its heating, non-oxidizing roasting to obtain a product with a reduction to rO2, 20% re-reduction with a mixture of gases containing reducing agents (Na, CO) and methane, characterized in that in order to reduce consumption fuel and increase the metallurgical value of the finished product, the restoration is carried out in two stages, the first of which is carried out by reducing to 50–55% in countercurrent mode with reducing gas, to which The products of combustion of natural gas burned with an air excess factor of 0.4-0.42 are added, and the second is carried out in reducing gas in the flow mode — moreover, the gas participating in the first stage re-reduction is used to burn the ore by burning it in the layer of air supplied through the peak burners at two levels along the height of the burning zone with costs corresponding to a = 0.7-0.8 and a 1.7-1.9 at the lower and upper levels, respectively. Carriage X-. pЈ | Natural gas To melon mpyftf 803tfyx 7 7 7