JPS60245732A - Method of dead burning iron ore pellet on moving grate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for hard-burning iron ore pellets on a moving grate by flowing hot gas under oxidizing conditions, which The present invention relates to a method of the type in which carbon-containing solid materials are incorporated into the pere-nod to supply a portion of the heat.

[Summary of the invention]

The present invention is a method of hard-burning iron ore pellets on a moving grate using high-temperature gas, in which the pellets are excessively mixed with a carbon-containing solid material that provides part of the heat required for hard-burning, and the high-temperature gas is By forcing the flow through the pellet bed using negative pressure in the sintering zone, the throughput of the pellet sintering machine and the quality of the sintered pellets and throat are maintained at a good level, and equipment costs are reduced for the same processing capacity. It has been made possible.

[Conventional technology and problems]

The hard-burning operation of iron ore pellets is approximately 1,200 to 1,
It is carried out at a temperature of 300° C. on a straight or circular moving grate (also known as a belle-throat sintering machine) equipped with a gas hood. This kind of bere-nodori is a lucky opportunity,
Viewed in the direction of movement, it has various processing zones: a drying zone, a sintering zone and a cooling zone.

These zones can be divided into, for example, a pre-drying zone, a drying zone, a heating zone, a pre-sintering zone, a main sintering zone, a post-sintering zone, a first cooling zone and a second cooling zone. .

In the case of oxidative hardening, the iron contained in the treated steel is in its highest oxidation state, ie as PetO*. Magnetic bere throat, i.e. magnetite CPe3
In the case of hard burning of bere-throat containing 0a), the amount of heat provided by the high-temperature gas may be less than in the case of hematite-based pellets. Because bi, Fe3O4 to F
This is because oxidation to ezO3 is an exothermic reaction. The unit throughput of a pellet sintering machine largely depends on the magnetite content of the ore to be processed, and increases with increasing magnetite content. Therefore, many experiments have been conducted to improve the throughput when processing hematite. In this case, finely divided carbon-containing solid material is mixed into the pellets.

As a result, the unit processing capacity improves considerably.When the content of force-fixing carbon (hereinafter referred to as Cfix) exceeds about 1.3%, the compressive strength of the pellet decreases significantly, and the unit processing capacity also increases due to the C8,8 content. G2 decreases as . If the quality of the pellets is good, up to the above C288 content, the throughput will be improved and the exhaust gas amount and temperature will be reduced ('AufbereiTechnik', T
h12, 1973. p, 783-788), about 1.
3% Cfi
Almost the same amount of heat is generated as in the case of hexification of zO+, and F
ezG, which is almost sufficient for reduction to Fe5Oa.

Until now, when a carbon-containing solid material was mixed into a 1-gnetite pellet, the strength of the pellet was significantly reduced.

[Means for solving problems]

The object of the present invention is to maintain good throughput and pellet quality of a pellet sintering machine, and to further reduce aw J energy consumption.

This purpose, according to the present invention, is to increase the Cfi This is achieved by increasing the amount of additive material required for the decomposition and by forcing the hot gas to flow through the pellet bed with a negative pressure of 5 to 20 mbar in the sintering zone of the moving grate. The pellets can be comprised of Lungs-pure hematite ore or a mixture of hematite and magnetite ores. The carbon-containing solid material can be composed of highly or weakly reactive coal. This coal may contain small or large amounts of volatile components. The amount of C fix supplied by the coal can be up to about 50% greater than the stoichiometric amount. In this case, stoichiometry always refers to the hematite content of the ore or ore mixture in the dry state.

If an additive, such as a basic carbonate, is added to the ore, this additive consumes heat during decomposition. In this case, the Cfix content may be correspondingly increased in excess of the amount required to replenish the heat consumed by combustion. The amount added can likewise be in excess of up to about 50%.

In the case of pure magnetite-based ores, Cr i

The carbon-containing material is added to the mixture at the required particle size for pelletization.

The underpressure for passing the hot gas through the pellet bed in the sintering zone is significantly reduced to 5-20 mbar compared to the values for conventional pellet sintering, ie about 30-40 mbar. The term "hard-burning" means heat treatment of the pellet at a temperature of about 1,250°C or higher. Unit gas volume (gas volume per 1 kg of charge in the sintering zone Nm)
' (N m3 is a unit indicating the volume of gas in m3 under standard conditions of 0°C and 11 atm)) also decreases correspondingly. The term "sintering zone" includes a heating zone that heats the dry pellets to the desired sintering temperature and an actual sintering zone that maintains the pellets at the desired sintering temperature.

Reducing the negative pressure in the sintering zone and increasing the CfiX content of the pellets surprisingly allows the mechanical strength of the pellets to be maintained and the pellets to be 1. The reduction ability of pellets can be improved, the capacity of the pellet sintering machine can be maintained, and the consumption of electrical energy and hot gas can be reduced.

For coals with a lower proportion of volatile combustibles, the Cfi of pellets is lower than for coals with a higher proportion of volatile combustibles.
What is necessary is to increase the X content.

The optimum C7,8 content and negative pressure for each operating case can be determined from experience.

According to a preferred embodiment of the invention, in the suction drying zone 5
Hot gas is forced through the pellet bed by means of a negative pressure of ~20 mbar. Drying is generally carried out in two stages. The first stage performs pressure drying, in which the hot gas is pumped from below to above through the pellet bed. In the second stage, suction drying is carried out, in which case the hot gas is suctioned from above to below through the bed. The advantages are further increased by the reduced vacuum and unit gas volume in the suction drying zone.

According to another preferred embodiment of the invention, hot gas flows through the pellet bed in the sintering zone of the moving grate with a negative pressure of 10 to 15 mbar. Particularly favorable results are obtained at the negative pressures and corresponding gas quantities.

According to yet another preferred configuration of the present invention, the hematite-based pellet has a 1.7 to 2.0
% by weight of Cfi The amount of Cf i X added in this case relates to the hematite content of the ore or ore mixture.

If heat-consuming additives are added to the ore, the amount added can be added to the hematite content.

If Cf1x is added based on this total value, extremely good results can be obtained.

According to yet another preferred configuration of the present invention, the hematite pellets contain 1.8 to 1.9% by weight of the dry state.
Mix 0□8 of the mixture and pelletize it.

In this case as well, the amount of the heat-consuming additive may be added depending on the case. Particularly good results are obtained with this incorporation.

〔Example〕

The present invention will be described in detail with reference to examples. The analytical values of concentrated hematite are as follows (% by weight relative to dry ore).

Fe total amount 66.6 FeLO,9 SiOz 2.6 A 11 zo30.93 CaO<0. O5 MgO〈0.05 TjOz　0.06 P < 0.03 The analytical values of concentrated magnetite are as follows.

(Weight % based on dry ore) Fe Total amount 65.6 Fe] 118.7 SiO71,6 A p 203 0,93 Mg0 0.58 P O,04 3 0,20 The analytical values of charcoal are as follows (dry (% by weight relative to charcoal).

Ct,

CrlX88.7 Ash content 3.1 Volatile content 8.2 The analytical values of coke are as follows (% by weight relative to dry coke).

Cf1x 80.1 Ash 13.9 Volatile 5.3 Sintering of the pellets was carried out on a 26.5 cm diameter pan.

Table 1 shows experimental results regarding hematite pellets. Pellets were made by adding 22% by weight Ca(OH) and 2% by weight CaCO. The solid fuel added is shown in the table. The moisture content of raw pellets is 8.8-9.
It was 75%. The first stage drying was carried out as pressure drying. That is, gas was pumped from below to the other side through the charge. Suction drying, heating and sintering were carried out by suctioning gas through from above to below. The "suction zone" includes the above three steps.

Table 3 shows the experimental results regarding magnetite pellets.

The pellets are 10% by weight of dolomite and hentoni)
It was prepared by adding 0.5% by weight. The moisture content of the pellets was 9.0-9.3%.

(Continued below in margin on next page) 5th ward. to . Pus The K-double bottle. .

　K　A　Stomach　0　Riの　Hetsu　ζ ; To p.2.

1 田1-E Shin Hansho [Effects of the Invention] According to the present invention, the heat consumption and energy consumption of the pellet sintering machine are reduced, and the sintered pellets have good strength and reducibility. However, equipment costs are reduced for the same processing capacity.

The invention is summarized as follows.

In the method of hard-sintering iron ore pellets on a moving grate, the Cfi51 content in the pellets reduces hematite to magnetite in order to reduce the energy consumption during sintering under oxidizing conditions. The carbon-containing solid material is incorporated into the pellets in an amount greater than the stoichiometric amount needed to decompose the heat-consuming additive material. The hot gas is forced through the pellet bed in the sintering zone of the moving grate with a negative pressure of 5 to 20 mbar.

Agent Katsu Ueya Yoshio Tsuneba

Claims (1)

[Claims] 1. A method of hard-burning iron ore pellets on a moving grate with a flowing hot gas under oxidizing conditions, the carbon-containing solid material providing part of the heat required for hard-burning. in which the fixed carbon content of the carbon-containing solid material incorporated into the pellets is greater than the stoichiometric amount required to reduce hematite to magnetophyte, and/or the thermal in an amount greater than that required to decompose the added substance that consumes it;
and a method for hard-burning iron ore pellets, characterized in that the hot gas is forced through the pellet bed in the sintering zone of a moving grate with a negative pressure of 5 to 20 mbar. 2. Process according to claim 1, characterized in that the hot gas is passed through the pellet bed in the suction drying zone with a negative pressure of 5 to 20 mbar. 3. Move the high temperature gas in the sintering zone of the grate for 10~
3. A method as claimed in claim 1, characterized in that the flow is carried out through the bed under a negative pressure of 15 mbar. 4. The method according to any one of claims 1 to 3, characterized in that 1.7 to 2.0% by weight of fixed carbon based on the dry ore is mixed into the hematite pellets. Method. 5. The method according to claim 4, characterized in that fixed carbon is mixed into the hematite pellets in an amount of 1.8 to 1.9% by weight based on the dry ore.