SU1315478A1 - Method for roasting sideritic ores and shaft furnace for effecting same - Google Patents

Abstract

The invention relates to metallurgy, to methods for preparing iron ore raw materials for metallurgical processing. The aim of the invention is to reduce the consumption of natural gas in the firing process while increasing the yield of the product. According to the invention, the burning zone with temperatures of 600-1000 ° C is divided into the upper burning zone by products of the complete combustion of natural gas and the lower combustion zone which is additionally supplied directly to the natural gas bed. As the ore quality decreases, depending on the ratio of magnesium carbonate and calcium to iron carbonate in the range of 0.3-0.9, the amount of natural gas supplied to the layer increases with respect to the gas burned in the furnace from 0.05 to 1, with Thereby, the specific gas consumption for firing increases from 24-26 to 47-49 m / t of burnt ore. In order to carry out the process, it is necessary in the shaft furnace below the arches for supplying the combustion products of natural gas in the external furnace to place the cores for supplying the natural gas directly to the material layer. In this case, the distance from cores to the arch is 0.2-0.3 of the height of the firing areas. Gas afterburning is carried out with heated air exhausted from the cooling section. 2 sec. f-ly, 2 ill. i (L SP 4 00

Description

to the range, 13 The invention relates to ferrous metallurgy and can be used in the firing of lump siderite ores in shaft furnaces.

The aim of the invention is to reduce the consumption of natural gas in the firing process while increasing the yield of the product.

. The goal is achieved by the method of burning siderite ores in a shaft furnace, which includes heating, decarbonating roasting at 600–1000 ° C and cooling lump: ore, roasting is carried out sequentially in two stages: first, due to the physical heat of natural gas combustion products, supplied from the external furnace and the lower part of the burning zone, then while simultaneously burning in the layer of natural gas material with air coming from the furnace cooling zone, and depending on the material composition of siderite ores with an increase in the ratio of magnesium and calcium carbonates to iron carbonate

t S 9ll e 2lFeCO,

0.9 proportionally increases the amount of natural gas supplied to the layer within its ratio to the constant consumption of natural gas in furnace 1: (20-) with a corresponding increase in the specific consumption of natural gas for roasting from 24-26 to 47-49 calcined ore,

In a furnace, containing in the burning zone of the mine, there are 1; 1e vertical walls, an external furnace, arches for supplying the combustion products, cores for the supply of natural gas are installed below the arches at a distance of 0.2-0.3 heights of the mines of the burning zone. Separation of the firing process at e) of the stage and, accordingly, the area of the zone into two parts, allows regulation of the temperature mode of this zone depending on the material composition of the ore by changing the amount of natural gas fed to the layer.

When firing rich ore with a low content of waste rock and iron, the accumulating capacity of the preheating zone of the shaft furnace is enough to recover the heat of combustion products of natural gas combusted in the external furnace, Kolosh4782 temperature

in this case, the gas does not exceed 150 C. If the ratio between carbonates increases, the consumption of Heo6xofaiMO will increase

5 gas firing process. However, to supply all the gas in the furnace is irrational. In this case, the amount of combustion products and the temperature of the flue gas increase, since the consumption O of heat required to heat the ore to 600 ° C (the temperature at which the dissociation of siderolesite, the main iron-containing mineral of siderite ore, begins), remains constant.

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In order for the quantity and temperature of the top gas to remain virtually unchanged, a part of the natural gas must be pushed into the bed.

Q to the base of the burning zone, which is due to air supplied from the cooling zone of the shaft furnace, the flow rate of which remains constant and does not depend on the material composition of the ore,

5 It is not rational to burn all the natural gas in the bed because of the unfavorable conditions of gas and air mixing in the bed. Calculations show that with an increase in the carbonate- ratio.

0 tons in ore in the range of 0.3-0.9, the total consumption of natural gas should be increased from 24-26 to 47-49 m / t, and the ratio between the amount of natural gas supplied to

-, - a layer of material PI in the furnace, must be maintained within 1: (20-1). Poor siderite ores with a high content of waste rock, which includes calcium carbonate and

{p magnesium (ratio, 9) and low iron content are substandard. As already mentioned, when the content of iron in the ore is decreased. natural gas consumption is higher

j of the indicated limits due to an increase in its supply to the layer of material in the lower part of the burning zone, leaving the gas flow rate into the furnace constant. In this case, the amount and temperature of the flash gas is practically unchanged, the efficiency of the mixture remains high, and the total gas consumption for firing is low. Natural gas is fed to the n: the bottom of the sottbi roasting, since the decomposition is carj. Magnesium bonates and, especially, calcium goes in the high-temperature part of the burning zone (more than 800 C) with a large heat absorption. Combining the combustion process in the bed with the dissoc313 process

The carbonation method makes it possible to obtain a favorable temperature profile in the lower part of the burning zone and carry out the process with high intensity without the formation of cakes.

Since the amount of air entering the combustion from the cooling zone into the burning zone of the shaft furnace throughout the entire range of changes in the specific consumption of natural gas supplied to the layer is much higher than stoichiometric, there is no danger of the formation of free carbon from the thermal decomposition of natural gas.

When sintering rich siderite ore (, 3), keeping the ratio between the consumption of natural gas in the material layer and the furnace less than 1:20 is impractical, since in this case a slight gain in furnace efficiency is leveled out by the structural difficulties of supplying gas to the layer. Since low-grade ores with a carbonate ratio, 9 are substandard, the ratio between the gas consumption in the layer and the furnace of the shaft furnace should not exceed 1: 1. If necessary, such dolomitized siderite ores will

in accordance with design considerations, it is burned in the traditional way, burning all natural gas in a layer of material, as is done in lime kiln and dolomite kilns for burning.

Placement of cores for supplying natural gas to the layer of material below the arches at a distance of 0.2-0.3 heights of the firing zone mines is made taking into account the kinetic regularities of the processes of burning natural gas in the layer and the dissociation of carbonates that are part of siderite ore, and allows to obtain a rational temperature regime of the burning zone with a change in the material composition of the ore

In the case of reducing the distance from cores to the arches of the burning zone less than 0.2 of the height of the mines, there is a risk of excessive temperature rise and the formation of cakes on the horizon of the supply of combustion products from the furnace to the bed, since in this area it is possible that some natural gas will not burn due to insufficient height at the bottom of the firing zone.

An excessive increase in the height of the lower part of the burning zone (distance from

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50

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five

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cores to arches more than 0.3 of the height of the mines) is irrational, since it leads to the appearance of a buffer zone and a decrease in the specific productivity of the furnace.

In Fig.1 schematically shows a furnace, a cross-section; figure 2 is the same longitudinal section.

The shaft kiln consists of loading hoppers 1, shafts 2 formed by vertical walls, arches 3 with gas distribution windows 4 for supplying combustion products to the upper part of the burning zone. The windows through the flame channels 5 are connected to a remote firebox 6, equipped with burners 7. In the upper part of the furnace there is a gas outlet 8 with a throttle valve 9, which provides for regulation of the vacuum in the furnace. The shaft furnace has three zones: preheating, roasting and cooling.

The burning zone comprises mines 2 formed by vertical walls supported by Hd arches 3 for supplying combustion products. Below the arches at a distance of 0.25 of the height of the shafts, cores 10 were installed to supply natural gas.

In the cooling zone of the shaft furnace there are boxes for inlet 1 1 and outlet 12 of cooling air. To unload the cooled and calcined material, drum feeders 13 and conveyor 14 are mounted.

The furnace works as follows.

In the silos 1 of the shaft furnace, with the help of a loading device, lumpy sideriteous ore of a fraction of 20-60 mm is loaded, which enters the heating and calcining zones of the shaft furnace. Preheating the ore to 600 ° C and firing in the upper part of the burning zone lead to a countercurrent of gas and material due to the physical heat of the products of complete combustion of natural gas. The combustion of natural gas is carried out in a remote firebox 6 of a shaft furnace with an air flow ratio of about 1.8-2.0. The vacuum in the furnace of the shaft furnace is maintained at a level of 20–40 Pa with on. power of the throttle valve 9. Products of complete combustion with a temperature of 950-1050 C come from the lower part of the burning zone and from the furnace through the fire ducts 5 through the distribution windows 4 to the upper part of the burning zone of the shaft furnace. The final roasting of the ore is carried out in the lower part of the burning zone while simultaneously burning

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gas c. layer of material at 950-1050 ° C. Natural gas is supplied to the lower part of the burning zone by means of cores 10 through channels and windows located in them. Further, the material enters the cooling zone of the shaft furnace, where it is cooled in three stages in the countercurrent – flow –– counterflow mode. The cooling air enters the box 11 and is divided into two streams: a part goes to the upper part of the cooling zone and further to the burning zone of the shaft furnace, the rest of the air enters the middle part of the cooling zone and is drained from the furnace when the boxes 12 are cooled. 60-80 ° C. The product is discharged by the drum feeders 13 to the conveyor 14 and fed into the screening and magnetic separation housing. When calcining siderite ore with a FeCOj content of 58.0%, MgCO 21.5%, CaCO, 7.4% - 0.5), the specific consumption of natural gas for roasting is m / t of burnt ore, and the gas consumption in the furnace 24 m / t, in a layer m / t (1: 3 ratio). In case of deterioration of the quality of the original

ores (relative - | - - - - 0.7)

It is necessary to increase the consumption of natural gas in the lower part of the burning zone to 16 m / t of burnt ore, leaving pro consumption in the furnace constant (24 m / t). The specific consumption of natural gas for firing will be 40, the ratio between the consumption of gas in the layer and the furnace 1: 1.5.

The proposed method of roasting siderite ore provides an increase in natural gas savings on roasting compared with the known from 10 to 15%, depending on the material composition

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Claims (2)

source ore at high efficiency of the burning process. Invention 1. Method of roasting siderite ores, including heating, decarbonizing calcination by products of complete combustion of natural gas with a temperature of 600–1000 ° C, supplied from a remote combustion chamber, and cooling of classified lumpy ore in a shaft furnace, in a manner that, in order to reduce the consumption of natural gas and increase yield of the product in the lower part of the zone firing, natural gas from the cooling zone is introduced into the layer of material and burned with natural gas, and with an increase in the ratio MgC04 + CaCOe from ,, „y; from 0.3 to 0.9, the amount of gas burned in the layer is directly proportionally increased relative to the constant consumption of natural gas in the furnace from 1; 20 to 1: 1, while the total consumption of primary gas o is increased from 24-26 to 47 - 49 m / t. 2. A shaft kiln for calcining siderite ores, containing mines for burning, formed by the vertical walls of the roof, a remote combustion chamber connected to the distributors of combustion products, arches with windows, loading and unloading units and the lower part of the product cooling furnace, which is designed to reduce the consumption of natural gas and increase the yield suitable product below the arches at a distance equal to 0.2-0.3 of the height of the firing shaft, the furnace is equipped with cores for supplying natural gas to the material layer. Fi & .1 Editor N.Egorova Compiled by A. Saveliev Tehred A. Kravchuk Order 2317/26 Circulation 549Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5   --- - - - - - I --- “-I - ... |.„ ..... Production and printing company, Uzhgorod, Projecto st., A Proofreader T. Kolb