SU1235910A1 - Method of thermal treatment of polydisperse ores in secondary restoration chamber - Google Patents

Description

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This invention relates to the preparation of iron ore in ferrous; metallurgy, namely magnetizing roasting polydisperse iron ore.

The aim of the invention is to increase productivity and improve the quality of the finished product. The raw ore with an average particle size of 0.1-0.6 mm loaded into the aggregate and solid fuel is fed into the furnace with a step-weighted layer (CBG), in which moisture is removed from it, heat up to 900-1000 ° C and produce partial recovery (up to 20-30%). The mixture is then fed to the post-recovery chamber. In this case, the charge (a mixture of ore and solid fuel) in the furnace is transferred from stage to stage in a suspended state towards the re-reduction chamber under the influence of high-speed air streams fed through tuyeres. These streams after decay

speeds move under the roof

towards the remanufacturing chamber, go down and move to the outlet nozzle. In the area of the first type of tuyeres, exhaust gases are removed from the furnace.

The solid fuel transported with the material stream is heated, ignited at 700 ° C, partially burned in the preheating zone in an oxidizing medium (giving up its heat to the intensification of heat and mass transfer processes) and forms reducing components (H, CO) of the gas phase in the partial furnace recovery.

The process of ore reduction is basically (by 80-100%) proceeding and is fully completed in the pre-Recovery chamber.

The use of solid Foshshva with a calorific value of 5000-6000 kcal / kg in the process causes the formation in a dense renewable layer of a limited number of fuel particles with a higher thermal output. For the purpose of uniform heat treatment of such a layer, the rate of descent of the material in the cleaning chamber should be set within 19-25 mm / min. This ensures the reduction of iron ore to a degree of 120-140% (in magnetite) and the allowable loss of solid fuel with finished products. At a lower rate of descent of the material (less than 19 mm / min), when the high quality of the finished product is achieved, the specific productivity of the process decreases (to 16-20%). At a higher rate of descent of the material (more than 25 mm / min), the degree of reduction of the finished product decreases below 120% and, accordingly, the degree of iron extraction from the ore decreases with enrichment. Solid fuel with a calorific value higher than 6000 kcal / kg is practically not used in ferrous metallurgy. When the calorific value of solid fuel is lower than 5000 kcal / kg, a greater amount of fuel is necessary and an adjustment of the rate of descent of the material in the recovery chamber.

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The decrease in the calorific value of the fuel from 5000 kcal / kg for every 1000 kcal / kg should be accompanied

by increasing the gathering speed of the material0

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la from 25 to 3-6 mm / min.

The number of particles of coal in the charge is determined by its size and calorific value. The content of coal in the charge is determined mainly by the calorific value, i.e. than; the poorer the coal, the (by weight), respectively, its greater in the charge. As a result, at the same coal size, the number of its particles in the charge is the greater, the lower the calorific value is) coal. An increase in the number of particles under the conditions of contact heat transfer (rebuilding chamber) contributes to an increase in the heat exchange surface and, consequently, to an intensification of the entire process. As a result, it becomes possible to increase the rate of descent of the charge in the re-recovery chamber.

Thus, a decrease in the thermal capacity of coal requires an increase in its total mass in the charge flow, an increase in the consumption of coal at 0 of its one-shot size leads to an increase in coal particles in the charge, an increase in the number of coal particles in the charge causes a reduction in the ore and coal re-recovery chamber and, therefore, an intensification in the whole process. The increase in the rate of heat and mass transfer processes makes it possible in the chamber

the recovery of the increase of the charge rate, i.e. The evolution of the entire process. When the material gathering rate is less than 3 mm / min for every 1000 kcal / k, the calorific value of the fuel decreases without improving the quality of the finished product, the specific productivity of the process decreases. With a larger increment in the rate of material flow (more than 6 mm / min for every 100.0 kcal / kg decrease in the fuel calorific value), the degree of recovery of the finished product decreases — the degree of iron extraction from the ore decreases and decreases.

In SHS furnaces magnetizing roasting of iron ores, heat treatment is subjected to a mixture with an average particle size of 0.1-0.6 mm with a particle size of coal in the range of 0.1-4.0 mm. The smaller particle size of the coal particles causes them to get into the leaving gases and out of the furnace (i.e., irretrievable loss of fuel). The upper limit of coal size is limited, firstly, by the conditions for the completion of its reaction in the pre-reduction chamber (the carbon of the larger particles of the coal does not have time to react and is irretrievably lost from the process with the finished product), secondly, by the conditions of its transportation steps m sbs.

Example. Solid fuel with an average particle size of 1.2 mm and with a calorific value of 5400 kcal / kg is included in the ore stream on a conveyor belt. The prepared mixture is fed through a charging device into the SHS furnace and subsequently subjected to drying, heating, partial reduction, and sent to the secondary recovery chamber. The gathering of the material of this chamber is set to 23 mm / million. This ensures the reduction of iron ore to a degree of 130% and the content of solid fuel and finished products is not more than 0.2% (carbon). The recovered ore is loaded and sent to enrichment.

The decrease in the calorific value of fuel from 5400 to .3400 kcal / kg is accompanied by an increase in the rate of descent of the material to a value of 35 mm / mN.

When using coal having a calorific value of 1690 cal / kg and feeding the required amount into the layer

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It is necessary to include at least 21–23% coal in the carbon mixture to complete the reduction process. With a coal size of 0.1–4.0 mm, in the retrofit chamber, almost every ore particle is in contact with the coal particle and the contact heat transfer is extremely intensified (1–1 m, that with a calorific value of 5,000 kcal / kg, the proportion of coal in the charge is 4%). 5% and ore particles are often separated from coal particles by 2-4 caliber pieces). Direct contact of the ore particles and coal causes the completion of the reduction of iron oxides in the monolayer. The productivity of the process is increased several times (on average, 2-5 times). Interestingly, from this point of view, the use of lean fuels, such as shale, is most preferable in SHS furnaces.

The prepared mixture with coal (calorific value of 5000 kcal / kg) is fed through a charging device into an SHS furnace and subsequently subjected to drying, heating, partial reduction, and sent to the re-reduction chamber. The convergence in this chamber is set to 19 MM / NfflH. At the same time, iron ore is reduced to 120% and the solid fuel content in the finished product is higher than 0.25% (carbon).

The reduction in the rate of descent of the material in the after-treatment chamber from 19 to 15 mm / min leads to the fact that with the high quality of the finished product achieved, the specific productivity of the process decreases by 4%.

Reducing the calorific value of the fuel, for example, from 5000 to 3000 kcal / kg, is accompanied by an increase in the rate of descent of the material to до from 5000 + 3000 00, /

Faces 25 + -Gopp -3 31 mm / min,

where 3 mm / min is the increment of the rate of descent of the material for every 1000 kcal / kg decrease in the calorific value of the fuel.

At this rate, iron ore is reduced to 120-124% and the degree of iron recovery is high. With a smaller increment of the rate of descent of the material, even at 2 mm / min, the degree of recovery increases to 145–147% (at which

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the degree of iron extraction during enrichment does not increase), and the specific productivity of nrocess decreases by 1.5 times.

The recovery rate in a dense lowering layer with a layer is directly proportional to the optimal rate of discharge of charge for each case. In our case, a recovery rate of 0.8% / min corresponds to a descent rate of 19 mm / min, and a recovery rate of 2% / min corresponds to a descent rate of

Note: The average ore size is 0.28 kM, the run is 0.1-0.6 mm.

The average coal size is 2.10 mm, the range is 0.1-4.0 mm.

You can see from the table that a decrease in the calorific value of fuel from 5020-5410 to 3060-3400 kcal / kg causes, on the one hand, due to a decrease in the ore content in the charge, a decrease in the specific productivity of the process by 3.5-5,, 8%, with another . cTopoHbij due to the intensification of the process (an increase in the rate of discharge of the charge) an increase in the specific productivity by 25.8-45.6%. Thus, an increase in the contacts of ore particles and fuel by about 2 times leads to a corresponding increase in the intensity of the process. As a result, when the calorific value of the fuel decreases from 5020-5410 to 3060-3400 kcal / kg and the carbon content in the charge is kept constant

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60 mm / min. All intermediate values are determined by the known proportional ratio). Deviations from these ratios are insignificant and are determined by the type of ore being recovered.

The table contains examples of the use of various coals (experimental data on the restoration of solitic ores in a descending transition layer).

the specific productivity of the recovery process in the pouring layer increases from 4.50-5.35 to 7.16 - 7.21 t / m, h. At the same time, the degree of reduction (in magnetite) of ore from 120-130 to 123-132% and the yield of concentrate from ore from 56-58 to 61-64% increase.

Thus, the quality of the finished product is improved.

The amount of coal depends on the type of ore being burned and the amount of carbon in the coal. The smaller the carbon in the grggle, the more proportionally its quantity is in the volume of the charge and, accordingly, the greater the amount of coal particles with its size being the same in all cases.

712359108

The application of the invention of the provision of magnetite ore to 140% and

The increase in the specific production of the degree of iron extraction to 82-85%,

aggregate by 16–20%, a decrease in the unreacted content of the reduction of total carbon to 0.3–0.5% (abs).

Composition1 {Body A. Saveliev Editor G. Volkova Tehred M. Khodanych Corrector T. Kolb

Order 3061/23 Circulation 552Subscription

VNIIPI USSR State Committee

for inventions and discoveries II3035, Moscow, Zh-35, Raushsk nab. 4/5

Production and printing company, Uzhgorod, st. Project, 4

Claims (1)

METHOD FOR THERMAL TREATMENT OF POLYDISPERSION ORES IN THE RECOVERY CHAMBER mainly of a step-weighted layer furnace for magnetizing roasting of iron ores, including the supply of a heated mixture of iron ores and a solid reducing agent with a particle size of 0.1-4.0 mm, reduction in a drop-down forced non-filtering and dense compact the finished product, b, characterized in that, in order to increase productivity and improve the quality of the finished product, the rate of descent of the dense layer at a calorific value of solid fuel 5000-6000 kcal / kg is set equal to 19-25 mm / min, with a decrease in calorific value from 5000 kcal / kg for every 1000 kcal / kg, the ratio of ore-carbon remains constant, and the speed increases from 25 mm / min by 3-6 mm / min SU. „, 1235910 ί