WO2018088941A1

WO2018088941A1 - Charge for producing iron-ore pellets (variants)

Info

Publication number: WO2018088941A1
Application number: PCT/RU2017/000855
Authority: WO
Inventors: Владимир Андреевич КОБЕЛЕВ; Георгий Александрович НЕЧКИН; Михаил Владимирович МАМАЕВ; Алексей Владимирович ЛЫСЕНКО; Игорь Петрович БЕЛИКОВ
Priority date: 2016-11-14
Filing date: 2017-11-17
Publication date: 2018-05-17
Also published as: EP3578672A4; EP3578672A1; RU2637850C1; CN110199037A; BR112019014466A2; US20200010922A1

Abstract

The invention relates to the field of producing iron-ore pellets for blast-furnace smelting. In a first variant, a charge contains iron-ore concentrate and manganiferous limestone as a binding agent and flux, the ratio of charge components in wt% being as follows:1.0-5.0 manganiferous limestone; and the balance iron-ore concentrate. In a second variant, the charge contains iron-ore concentrate, bauxite as a modifying agent, and manganiferous limestone as a binding agent and flux, the ratio of charge components in wt% being as follows:1.0-3.5 manganiferous limestone; 1.2-1.5 modifying additive; and the balance iron-ore concentrate. The invention raises the strength of green and sintered pellets while preserving a high iron content, reduces the softening-melting interval of the pellets in a blast furnace, and simplifies the production of iron-ore pellets.

Description

W

one

MIXTURE FOR OBTAINING IRON PELLETS

(OPTIONS)

The invention relates to the production of fluxed iron ore pellets for blast furnace smelting.

Various compositions of a mixture of pellets for blast furnace smelting are known. In the production of fluxed pellets, the mixture consists of iron ore concentrate, bentonite and fluxing additives - limestone, chalk or dolomite.

For example, from the USSR Author's Certificate JSfe 692879, a method is known for producing pellets from concentrates containing 4-10% silicon oxide in waste rock, fluxing of the mixture to a ratio of CaO / SiO ₂ = 0.5-1.3 is carried out with the introduction of magnesium oxide into it an amount providing a ratio of CaO: MgO = 1.5-3.9. After firing, cooling to a temperature of 700-900 ° C is carried out at a speed of 120-240 ° C / min.

The disadvantage of this composition of the charge is the high basicity, accompanied by a decrease in the iron content in the pellets, and the formation of glass in the structure of the pellets, reducing their strength.

The closest technical solution to the technical nature and the achieved result (the closest analogue is the prototype according to the first embodiment) relative to the claimed charge according to the first embodiment, is a mixture for producing pellets according to the copyright Certificate CCCP.N2 800200, which contains iron ore concentrate and a binder in the form of lime-containing material . In order to reduce the cost of metallurgical redistribution as a lime-containing material, the mixture contains a finely marl with a particle content of 2-0 microns 20-80% at the following ratio of ingredients,%: chalky marl 3-7, iron ore concentrate the rest.

The disadvantage of this solution is the high content of Si0 ₂ in the marl, which reduces the iron content in the pellets, the low strength of the raw pellets and the wide temperature range of softening-melting of the pellets in a blast furnace.

The closest technical solution in terms of technical nature and the achieved result (the closest analogue is the prototype in the second embodiment) with respect to the claimed charge in the second embodiment is a mixture for the production of pellets for metallization in shaft-type plants with their subsequent briquetting according to RF patent N ° 2202632 an invention containing iron ore material, bentonite, limestone and bauxite in the following ratio of components, wt.%: the sum of bentonite and limestone is 0.5-1.0; bauxite - 0.4-1.1; iron ore material - the rest.

The disadvantage of this composition of the charge is the low value of the basicity of the pellets, which determines a wide range of softening and melting in a blast furnace.

The objective of the invention is the development of a mixture to obtain iron ore pellets, which eliminated the disadvantages of known mixtures.

The technical result achieved by the invention is to increase the strength of raw and calcined pellets while maintaining a high iron content, reducing the softening-melting interval of pellets in a blast furnace., Simplifying the production of iron ore pellets. The technical result is achieved due to the fact that in the mixture for producing iron ore pellets according to the first embodiment, containing iron ore concentrate, flux and a binder, according to the invention, the mixture contains manganese limestone, intended for use as a binder and flux, the ratio of the components of the charge is, wt.%:

- manganese limestone - (1.0-5.0);

- iron ore concentrate - the rest.

The manganese content in manganese limestone is at least 6%.

In the mixture for producing iron ore pellets according to the second embodiment, containing iron ore concentrate, flux and a binder, according to the invention, the mixture contains bauxite, intended for use as a modifying additive, and manganese limestone, intended for use as both a binder and flux , the ratio of the components of the charge is, wt.%:

- manganese limestone - (1.0 - 3.5);

- modifying additive - (1.2 - 1.5);

- iron ore concentrate - the rest.

The manganese content in manganese limestone is at least 6%.

In the batch according to both options, the maintenance of a high iron content in the pellets is achieved due to the lower S1O2 content in the manganese limestone. The increase in the strength of raw pellets in the charge for both options is due to the increased water-physical properties of manganese limestone.

The increase in the strength of the calcined pellets in the charge according to the first embodiment (when the content of manganese limestone is within the limits stated in the first embodiment) is achieved by increasing the content of manganese oxide.

The lower limit of the content of manganese limestone in the mixture according to the first embodiment, that is, 1, 0%, is due to its minimum amount, capable of providing high strength of raw and calcined pellets. When the content of manganese limestone in the charge is less than 1.0%, the strength of the raw and calcined pellets decreases below the level that provides strength when using a finely shaped marl. When the content of manganese limestone in the mixture is less than 1%, the effect of manganese oxide on the softening and melting temperatures is weakly manifested.

The upper limit of the content of manganese limestone in the mixture according to the first embodiment, that is, 5%, is due to a decrease in the iron content in the pellets and the strength of the calcined pellets. At a greater than 5.0% content of manganese limestone in the charge, the strength of the calcined pellets decreases due to the formation of glass in their structure. The formation of glass also leads to a decrease in the softening temperature and an increase in the softening-melting interval.

In the charge according to the first embodiment, a decrease in the temperature range of softening-melting of the pellets is achieved due to the influence of manganese oxide (when the content of manganese limestone within the declared limits in the mixture according to the first embodiment) at the softening and melting temperatures of the pellets in the blast furnace.

The reduction of the softening-melting interval of the pellets in the blast furnace in the mixture according to the second embodiment is achieved due to the higher content of Al ₂ 0 ₃ in the pellets and the effect of manganese oxide on the softening and melting temperatures of the pellets in the blast furnace.

An additional decrease in the softening-melting interval of pellets in a blast furnace is achieved by modifying A1 ₂ 0 _{3 with} bauxite.

The increase in the strength of raw pellets in the charge according to the second embodiment is due to the increased water-physical properties of manganese limestone, and the increase in the strength of calcined pellets (when the content of manganese limestone is within the limits stated in the second variant) is ensured simultaneously by increasing the content of manganese oxide, and also due to the formation of the structure of the mineral - brownmillerite in the interaction of manganese limestone with aluminum oxide A1 ₂ 0z.

The lower limit of the content of manganese limestone in the mixture according to the second embodiment, that is, 1.0%, is due to its minimum amount, capable of providing high strength of raw and calcined pellets. With a lower than 1.0% content of manganese limestone in the charge, the strength of raw and calcined pellets decreases below the level that provides strength when using bentonite.

The upper limit of the content of manganese limestone in the mixture according to the second embodiment, that is, 3.5%, is due to a decrease in the iron content in the pellets and the strength of the calcined pellets. With a greater than 3.5% content of manganese limestone in the charge, the strength of the calcined pellets decreases due to the formation of glass in their structure.

The lower limit of the bauxite content in the charge according to the second embodiment, that is, 1.2%, is due to its minimum amount, at which a modifying effect on the softening and melting temperatures in the blast furnace is manifested. At a bauxite content lower than 1.2% in the charge, the influence of A1 ₂ 0 ₃ on the decrease in softening and melting temperatures is weak.

The upper limit of the bauxite content in the charge according to the second embodiment, that is, 1, 5%, is due to a decrease in the iron content in the pellets. With a greater than 1.5% content of bauxite in the charge, the iron content in the pellets decreases.

An example implementation of the invention.

The test mixture to obtain iron ore pellets was carried out in laboratory conditions. As the iron ore material used iron ore concentrate, the chemical composition of which is given in table. 1. The compositions of fluxes and bauxite are also given there. Bentonite, fluxes and bauxite were crushed in a ball mill to a particle size of less than 0.072 mm, introduced into the concentrate in a predetermined quantity, mixed, moistened and pellets were produced in a drum granulator with a particle size of 10-15 mm. Raw pellets were tested for strength by dropping from a height of 30 cm. Calcination was carried out in a muffle furnace with a programmed heat treatment mode at a maximum temperature of 1300 ° C. After firing and cooling, the pellets were tested for crushing strength according to GOST 24765-81, the chemical composition and softening-melting temperatures were determined according to GOST 26517-85. To compare the indicators, tests of the charge were carried out relative to the prototypes, respectively, according to the first and second options. The test results are presented in table. 2.

An analysis of the obtained results shows that the inventive charge for producing iron ore pellets in both cases achieves the stated goal of increasing the strength of raw and calcined pellets while maintaining a high iron content and reducing the softening-melting interval in a blast furnace.

The mixture according to both options for producing iron ore pellets in comparison with the corresponding prototypes increases the strength of raw pellets from 2.2 to 3.5-5.0 drops, the strength of calcined pellets from 250 to 313-510 kg / pellet, reduces the temperature range of softening-melting with 320 to 240-290 ° C, maintains a high iron content in the pellets.

The claimed technical solution can be implemented in industry with the achievement of the claimed technical result.

The simplification of the preparation of the charge is due to the fact that manganese limestone is intended for use as a flux and a binder (i.e., such a component of the mixture as a binder is not required separately).

As manganese limestone, natural raw materials (manganese ore) are used, characterized by a manganese content of at least 6%. Table 1. The chemical composition of the components of the charge,%

PMP - mass loss on ignition

0 Table 2. Test Results

The content in the mixture,%

Keycenter _r ant i n

D Btonenit

ABOUT

M ^th argantsey and ^breakfast vesyakvtn

1 - by

Bauxite

AU USSR Melopodob

L n

95.0 - - P s ^d ^to be internally ^pp syh okayshet 2,2 64,95 250 320

80020 marl

5.0 ^by ^p with ^p ace chisloyvnia ^z ^-,

0

2 99.2 - 0.8 - 2.7 6 Snoe ^p zhaie ^of a jelly vd6,69 265310

3 99.0 - 1.0 - 3.5 66.6% Aysha okath0 ^, 313 275

4 97.0 - 3.0 - 4.0 65.78 402 260

5 95.0 - 5.0 - 5.0 Pa 64,95 Wasps ^p n ^s ^p a daanechntvlivi 366240

6 94.5 - 5.5 - 6.5 64.75 3 ^by 5 burnt ossified ^, 0 255

7 - per ^/ round kg

patent

the T ^p ^dp empe atom ^at ^p us integral shaft JYS 97,9 0,6 Limestone ° Syapa ^p ^{azmyagchenilvleniya-,}

22026 0.4 1 3.0 66.12 260 390 32

8 98.1 - 0.8 1.1 2.8 66.33 275 340

9 97.8 - 1.0 1.2 3.9 66.21 360 290

10 96.7 - 2.0 1.3 4.2 65.77 450 270

11 95.0 - 3.5 1.5 4.5 65.08 510 265

12 94.4 - 4.0 1.6 4.9 64.84 335 280

Claims

CLAIM

1) A mixture for producing iron ore pellets containing iron ore concentrate, flux and a binder, characterized in that it contains manganese limestone, intended for use as a binder and flux, while the ratio of the components of the charge is, wt.%:

- manganese limestone - (1.0-5.0);

- iron ore concentrate - the rest.

2) The mixture according to claim 1, characterized in that the content of manganese in the manganese limestone is at least 6%.

3) A mixture for producing iron ore pellets containing iron ore concentrate, flux and a binder, characterized in that the mixture contains bauxite, intended for use as a modifying additive, and manganese limestone, intended for use both as a binder and flux , the ratio of the components of the charge is, wt.%:

- manganese limestone - (1.0 - 3.5);

- modifying additive - (1.2 - 1.5);

- iron ore concentrate - the rest.

4) The mixture according to claim 3, characterized in that the content of manganese in the manganese limestone is at least 6%.