JPH0610312B2 - Pretreatment method for sintering raw material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pretreatment method for a raw material for self-fluxing sinter.

(Prior Art) The self-fluxing sinter used as a blast furnace raw material is generally manufactured by the method described below. First, the powdered ore loaded from the ship is piled up in the powdered ore yard for each brand. After that, various powdered ores piled up are mixed by a bedding method at a preset ratio to obtain a blending powder.
This blending powder and each raw material such as coal stone, powder coke, and return ore are put in separate mixing tanks, and a predetermined amount of each raw material is continuously cut out from each mixing tank. This is sent to a primary mixer for water addition and granulation. If necessary, further granulate with a secondary mixer. The raw material (pseudo particles) granulated in this way is continuously supplied from the hopper onto the pallet of the sintering machine, and the coke on the surface layer of the raw material is ignited by the ignition furnace. Forced ventilation with the air box. By the above operation, a self-fluxing sintered ore as a blast furnace raw material is manufactured.

On the other hand, SI (normal temperature strength), RDI reduction powderability index), RI (reducibility index) are used as criteria for indicating the quality of sinter.
and so on. These qualities have a great influence on the fuel ratio, productivity, operability, etc. in a blast furnace using these sinters as raw materials. Therefore, various techniques have been studied conventionally. For example, a method of increasing the CaO weight content ratio / SiO ₂ weight content ratio (hereinafter, the weight content ratio is omitted and simply referred to as “CaO / SiO ₂ ”) of the sinter is proposed. However, CaO / SiO ₂ of the sintered ore needs to be uniquely determined depending on the operating conditions of the blast furnace, and cannot be applied in practice. Also, the Al ₂ O ₃ weight content ratio / SiO ₂ weight content ratio in the fine powder portion due to the refinement of the SiO ₂ source (hereinafter, the weight content ratio is omitted and simply referred to as “Al ₂ O
₃ / SiO ₂ ”. ), Or a method of preliminarily granulating South American powdered ore and coal stone with gangue such as quartz, etc., but both have a clear effect despite the increase in manufacturing cost. Is not obtained, and it has not been put to practical use industrially.

(Technical problem to be solved by the invention) The present invention provides a low {Al ₂ O ₃ weight content ratio / (Al ₂ O ₃
Weight content + Fe ₂ O ₃ weight content)}, (hereinafter,
Omitting the weight content ratio, simply saying “Al ₂ O ₃ / Al ₂ O ₃
+ Fe ₂ O ₃ ”. ) Fine ore and high SiO ₂
Weight content ratio (Hereinafter, the weight content ratio is omitted and simply "S
referred to as iO ₂ ". ) The CaO source mixed in the powdered ore is the average (CaO weight content ratio / SiO ₂ weight content ratio) value of all the sintering raw materials, (hereinafter, the weight content ratio is omitted and simply referred to as “average CaO / SiO ₂ value”). Higher Al ₂ O ₃ / Al ₂
O ₃ + Fe ₂ O ₃ powder ore has a low CaO / SiO ₂ composition, which suppresses the formation of strip-shaped calcium ferrite that is inferior in reducibility, and at the same time, forms an amorphous slag that is excellent in room-temperature strength and reduction powdering resistance. It is an object of the present invention to provide a method for accelerating the production of sinter, which has excellent room temperature strength, reduced pulverization property and reducibility, and is manufactured with high yield.

(Means for Solving the Technical Problem) The present invention is based on the chemical composition and the compounding ratio of various powdered ores to be mixed as a sintering raw material, {average Al ₂ O ₃ weight content ratio / (average Al ₂ O ₃ weight) of all powdered ores. Content ratio + average Fe ₂ O ₃ weight content ratio) value, (hereinafter, the weight content ratio is omitted and simply referred to as "average Al ₂ O ₃ / average Al ₂ O ₃ + average Fe ₂ O ₃
It is abbreviated as "value". ) And the average SiO ₂ amount are calculated, and various powder ores are classified on the basis of these average values, and the Al ₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ values lower than the above average values and higher than the above average values. The average Ca of all the sintering raw materials is the CaO source compounded as a solvent for the powdered ore having the amount of SiO _2.
It is a pretreatment method for a sintering raw material, which is characterized in that it is blended so as to have a value higher than the O / SiO ₂ value, and this mixture is mixed and granulated prior to mixing of all sintering raw materials and granulation.

(Detailed Description of the Invention) Sintered ore is composed of various mineral structures. That is, the quality of the sintered ore is determined by the quality (physical property value) and the composition ratio of these various structures. Therefore, first, various structures constituting the sintered ore were classified according to phase and morphology, and strength and reducibility of each structure were measured. As a result, the amorphous slag, which is a silicate compound, has a high strength, and the strip-shaped calcium ferrite (abbreviated as strip-shaped CaF hereinafter) present in the amorphous slag is reduced compared to other mineral structures. It was found that the sex was extremely poor. That is, if strip-shaped CaF is produced as another mineral structure (for example, acicular or fine-type calcium ferrite) and formation of amorphous slag that does not contain strip-shaped is promoted, a highly reducible sinter having high strength is obtained. Can be manufactured.

Therefore, the conditions for producing strip-shaped CaF existing in the amorphous slag were examined next. First, elemental analysis was performed on the strip-shaped CaF existing in the sintered ore using XMA.
This measurement revealed that the strip-shaped CaF has a higher Ca / Si ratio than the surrounding amorphous slag phase. Next, various powdered ores, limestones, and silica stones were used to carry out synthetic tests of sintered structures with various composition. As a result, in order to generate strip-shaped CaF, higher Al ₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ and higher CaO / S than the current raw material composition are used.
It has been found that this is the case when an iO ₂ composition is required and is fired at high temperature. That is, the actual sinter has a microscopic component segregation, and therefore, the Al content higher than the average composition of the sinter is
₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ and high CaO / Si
There is a region that becomes O _2, and strip-shaped CaF is present in the actual sinter.
Exists. Therefore, this high Al ₂ O ₃ / Al ₂
The generation of strip-shaped CaF is suppressed by reducing the region where O ₃ + Fe ₂ O ₃ and high CaO / SiO ₂ are formed.

Therefore, high Al ₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ and high Ca
As a method of reducing the O / SiO ₂ region, a method is considered in which all the sintering raw materials are finely pulverized and uniformly mixed to obtain the average composition of the sintered ore microscopically. However, this method is not industrially applicable because it causes a large increase in manufacturing cost.

Therefore, the present invention provides low Al ₂ O ₃ powder ore for sintering raw materials.
/ Al ₂ O ₃ + Fe ₂ O ₃ and high SiO ₂ powder ore by preferentially mixing and granulating the CaO source, the chemical composition of the main sintering raw material is changed to high Al under the same raw material mixing conditions.
₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ , low CaO / SiO ₂
The composition was adjusted.

The reason why the powdered ore containing the CaO source preferentially is defined as the high SiO ₂ powdered ore is that the raw material C containing the CaO source is preferentially mixed.
When the amount of increase in the aO / SiO ₂ value is constant, it is possible to lower the CaO / SiO ₂ of the main sintering raw material by making the powder ore containing the CaO source preferentially into the high SiO ₂ powder ore. is there.

(Effects of the Invention) Therefore, according to the present invention, strip-shaped Ca having inferior reducibility is inferior.
It suppresses the formation of F and promotes the formation of amorphous slag that is excellent in room temperature strength and resistance to reduction pulverization, and produces a sintered ore that is excellent in room temperature strength, reduction pulverization property, and reducibility with good yield. be able to.

(Example) Next, the Example of this invention is described.

The drawing shows an example of the case of making a process. First, the main sintering raw material powdered ore 1, optional reclaimed ore 3, limestone 4, silica stone 5 and powder coke 6 sent from the main sintering raw material line 7 to the mixing granulator 8, while CaO source preferential mixing Mixing granulator 1 for fine ore 2, return ore 3, limestone 4, silica 5 and powder coke 6 from CaO source priority blending line 9
Supply to 0. The mixture mixed in the mixing granulators 8 and 10 is mixed in the mixer 11 if necessary and then sintered in the sintering machine 12.

Next, an example in which the effect of the present invention is confirmed will be described.

Sintering pot test 1 Sintering pot conditions Raw material mixture Powder ore: 10 brands shown in Table 1 (A to D are South American powder ores,
E to J are powdered ores from Australia, India) Silica: Compounded so that SiO _{2 in the} product sintered ore will be 5.5%.

Limestone: Compounded so that CaO / SiO ₂ in the product sinter becomes 1.6.

Return ore: 20% for new raw material Powder coke: 4.5% for new raw material Firing condition Ignition: 1 minute Negative pressure: 1200 mmH ₂ O (constant) CaO source priority compounding condition 1) CaO source priority compounding (( Conventional method) 2) Method of the present invention 3) Comparative method (1) ... The total amount (A-D) of South American flour ore is C
aO source preferential formulation 4) Comparative method (2) ... Low Al ₂ O ₃ / Al ₂ O ₃ + Fe ₂
O ₃ the total amount of the fine ore (A~D, E, H) are shown the chemical composition and the mixing ratio of the fine ore subjected to the CaO source priority formulated CaO source priority recipe 2.

The ratio of silica stone, return ore and powder coke to the CaO source preferential mixing is determined according to the mixing ratio of each sintering raw material (powder ore).

Sinter pot test results As shown in Table 2, the sinter produced by the method of the present invention is
It can be seen that the quality and productivity are all superior to those of the conventional method. On the other hand, each of the comparative methods has little effect on the quality and productivity of the sinter and has almost no effect. This is because, in the comparative method, there are many powdered ores in which the CaO source is preferentially blended and there is a low Al ₂ O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ value, but the low SiO ₂ content results in the CaO source preferential blending (low Al _{2 O 3 / Al 2 O 3 +} Fe 2 O 3) of CaO / Si
If the amount of increase in O ₂ is constant, the main sintering raw material (high Al ₂
It is considered that this is because the decrease amount of CaO / SiO _{2 in} O ₃ / Al ₂ O ₃ + Fe ₂ O ₃ ) was small and the generation of strip-shaped CaF could not be suppressed.

The test was conducted by changing the powder coke blending amount, the powder coke blending ratio to the CaO source preferential blending, the silica stone blending amount, the limestone blending amount, and the like, and the same effects as those in the above-described examples were obtained.

Sintering pot test 2 Test conditions The raw material composition and firing conditions were the same as in Test Example 1. In addition, the CaO source preferential mixing condition is Test Example 1 for powdered ore.
Under the same conditions as in the method of the present invention, the total amount of silica stone and return ore was compounded with CaO source priority compounding.

Sintering Pot Test Results (Table 4) According to the method of the present invention, it is possible to improve the quality and productivity of the sintered ore by blending silica stone and return ore with CaO source preferential blending. This is because the main sintering material (high Al ₂ O ₃ / Al
₂ O ₃ + Fe ₂ O ₃ , low SiO ₂ ) CaO / SiO ₂
It is thought that this was due to the fact that

Even under these test conditions, powder coke content and CaO
A test was conducted in which the powder coke blending ratio, the silica stone blending amount, and the limestone blending amount were changed to the source-first blending, but the effects were the same.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is a block diagram showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Main powder ore for sintering raw materials, 2 ... Powder ore for preferential mixing of CaO sources, 3 ... Return ore, 4 ... Limestone, 5 ... Silica, 6 ... Powder coke, 7 ... Main sintering raw material line, 9 ... CaO source Priority compounding line, 8, 10 ... Mixing granulator, 11 ... Mixer, 12
… Sintering machine

Claims (1)

[Claims] 1. From the chemical composition and the compounding ratio of various powdered ores blended as a sintering raw material, {average Al ₂ O ₃ weight content ratio / (average Al ₂ O ₃ weight content ratio + average Fe ₂ O ₃
Weight content ratio)} value and average SiO ₂ weight content ratio value are calculated, and various powdered ores are classified based on these average values,
Lower than the average value {Al ₂ O ₃ weight content ratio / (Al
₂ O ₃ weight content ratio + Fe ₂ O ₃ weight content ratio)} value and a powder ore having a SiO ₂ weight content value higher than the above-mentioned average value, the CaO source compounded as a solvent is an average of all sintering raw materials ( CaO weight content ratio / SiO ₂ weight content ratio) is blended so as to be higher than the value, and this mixture is mixed and granulated prior to the mixing of all the sintering raw materials and the granulation. Pretreatment method.