JPH0437635A - Method for kneading powder coke and limestone - Google Patents

Abstract

PURPOSE:To reduce the cost of production by charging limestone and powder coke added with water just before charging into a drum washer installed before a grate furnace and kneading the material mixture. CONSTITUTION:The limestone of 4 to 15mm grain size and the powder coke of 7 to 12wt.% thereof are added with the water from a shower pipe 10 for water addition to increase the moisture content to 2 to 4wt.%, then such limestone and powder coke are charged from an introducing chute 9 into a rotary drum 8 of the drum washer 4 having feed vanes 6 and cutting vanes. The limestone and the powder coke are kneaded by the drum washer 4 to form the material mixture which does not separate the powder coke before being transferred to a calcination stage. This material mixture is stored in an ore tank 5 before the furnace. The material mixture is properly supplied from this tank into the grate furnace 1 and air is sucked from an exhaust duct 3 to ignite the gases by a gaseous C ignition burner 2, by which the material mixture is calcined to obtain the calcined matter.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for kneading coke powder and limestone in the process of producing quicklime for sintering raw material by firing limestone.

<Prior art> Generally, the sintered raw material charged into a blast furnace is supplied in the form of sintered ore, which is made by sintering and agglomerating powdered iron ore. It is made by mixing powdered limestone and sintering it.

However, when limestone is used, it is highly pulverized and is used as a sintering raw material, which impairs air permeability during the sintering process, resulting in problems in terms of productivity and sinter production cost.

If quicklime is used instead of limestone, it becomes gel-like slaked lime when mixed with water during the preparation of sintering mixture raw materials, which has a granulation effect in the sintered layer, improves air permeability, accelerates the sintering reaction, etc. It has been confirmed that it is more advantageous than limestone in terms of this, and that it can improve the quality of sintered ore.

In order to obtain quicklime, limestone can be decarboxylated by firing in a firing furnace such as a rotary kiln or shaft furnace as shown in the formula below, CaC0: + CaO + CO
z 42.9 Kcal/Knol (endothermic reaction) Conventionally, the limestone charged into the kiln was in the form of a lump (approximately 10 to 100 limestone) from the viewpoint of ventilation and workability, and the limestone was decarboxylated. As a heat source necessary for the reaction, fuel such as liquid fuel, gas fuel, or solid fuel (pulverized coal, etc.) was combusted in a burner.

<Problems to be solved by this invention> However, in the conventional manufacturing method, liquid fuel, gaseous fuel, etc. are expensive, and lump limestone is used.
There are problems with low thermal efficiency and poor productivity. In addition, there are major drawbacks such as the need for a crushing process in order to use it as a raw material for sintering, which increases the overall manufacturing cost.

In order to solve these problems, the applicant has already developed four to one
A mixed material made by adding coke powder to 5 mm of limestone and further adding water is charged into a preheater of a rotary kiln, the mixed material is fired without rolling in this preheater, and then cooled and heated in the rotary kiln. Limestone, which is easily pulverized, is pulverized in the gas transportation process to the sintering process without being crushed or sent to a rotary kiln.
An application has been filed for a method for producing quicklime that can be produced at low cost without the troubles caused by powdering (Japanese Patent Laid-Open No. 63-210047, Japanese Patent Application No. 63-57475, etc.).

The purpose of this invention is to provide a method for kneading coke powder and limestone that can produce a mixed material suitable for calcination at a low cost in the pre-calcination process in the quicklime production process using powdered limestone and coke powder as described above. do.

<Means for Solving the Problems> As shown in FIG.
In the production process of mixing aco:+) with coke powder (C) and water, and baking this mixed material without rolling using Grate 1 to produce quicklime (Cab),
Limestone (CaCO:+) and coke powder (
An appropriate amount of each of C) is charged, an appropriate amount of water is added immediately before the charging, and the mixed material is kneaded using a drum washer.

The size of limestone is 4-15mm, and the size of coke powder is 7-12mm.
%, and the water content is 2 to 4%.

<Function> The drum washer in the rotary kiln system is originally a device in which a large amount of water is poured together with limestone, etc., and the fine particles adhering to the limestone due to collisions between the stirring blades and the limestone are washed away. However, the equipment itself has the same structure as a kneading machine, and can be used as a continuous kneading machine by adjusting the moisture content to a low level without major modification. can be manufactured. It goes without saying that it can also be used as a conventional drum washer for limestone.

Since this process has a pumper that can store mixed materials, the drum washer can be operated intermittently, and kneading and washing can be performed intermittently, resulting in a significant reduction in equipment costs.

By adjusting the amount of water added so that the water content of the mixed material is within 2 to 4%, the material will adhere well to the limestone and be mixed well, and the adhesion of coke powder, etc. to the inside of the drum washer will be minimized. It can be held down.

The reason why the size of the limestone is set to 4 to 15 holes is because fine particles have poor air permeability and low production capacity, while coarse particles cannot be burnt to the core. The reason why coke powder was set at 7 to 12% was 7.
If it is less than %, the degree of firing will be poor, and if it is too much, it will be uneconomical (
This is due to high manufacturing costs).

<Embodiment> The present invention will be described below based on an illustrative embodiment. As shown in FIG. 1, this is an example of a quicklime production process using a preheater (grates) (2) of rotary kiln equipment. Rotary kiln equipment originally performs firing in the rotary kiln by exclusively firing C gas from a burner, and preheats in the preheater 1 with C gas from the rotary kiln, but in the present invention, in order to avoid powdering during firing, firing is performed in the preheater 1. Let's do it. Therefore, we changed the C gas exclusive combustion system to a coke powder exclusive combustion system, installed a new C gas ignition burner 2 as an ignition source in the preheater 1, used a mixed material of limestone, coke powder, and water, and The mixed material on the grid IA is fired by air suction.

A drum washer 4 and a furnace raw stone tank 5 are installed at the front stage of such a firing process, and the drum washer 4 is connected to a rotating drum 8 having a feeding blade 6 and a cutting blade 7, and a charging chute 9. Water addition shower pipe installed above 1
0.

In such a configuration, an appropriate amount of limestone (CaCO3) and coke breeze (C) are cut out, and immediately before charging, the shower pipe 1 is
A suitable amount of water is added according to 0, and such a mixed material is kneaded in a rotating drum 8 to produce a mixed material that can obtain a uniform baked product (quicklime) without separation of coke powder until the baking stage. .

Next, an example of removing adhering fine powder when limestone is fired by a drum washer, and an example of producing an adhering mixture by mixing coke powder with the limestone of the present invention will be shown.

From the above, it can be seen that the functions of the drum washer and kneader can be fully demonstrated using the same general equipment.

In addition, although the preheater of rotary kiln equipment has been described above, it goes without saying that the present invention can also be applied to quicklime firing in other grate furnaces.

<Effects of the Invention> As described above, the kneading method of the present invention uses the existing drum-on shear in the front stage of the grate furnace in the step of firing the mixed material of limestone, coke breeze, and water without rolling it in the grate furnace. Since it is used as a kneader to attach powdered coke to limestone, a mixed material suitable for calcination can be manufactured at low cost.

In addition, it can also be used as a drum washer as before.
Since the same general equipment can perform another high-value-added function, it is possible to significantly reduce capital investment and reduce quicklime manufacturing costs.

[Brief explanation of drawings]

FIG. 1 is a flow diagram of the equipment according to the present invention, and FIG. 2 is a schematic cross-sectional view showing the drum-on shear of the present invention. 1... Grate furnace (preheater) 1A... Grate, 3... Exhaust gas duct, 5... Furnace raw stone tank, 7... Cutting blade, 9... Charging chute, 2. ... Ignition burner 4 ... Drum washer 6 ... Feed vane 8 ... Rotating drum 10 ... Shower pipe for adding water

Claims (1)

[Claims] (1) In the production process where limestone, which is easily powdered, is mixed with coke powder and water, and this mixed material is fired without rolling using a grate furnace to produce quicklime, it is installed before the grate furnace. Charge appropriate amounts of limestone and coke powder into an existing drum washer, and add an appropriate amount of water immediately before charging.
A method for kneading coke powder and limestone, which is characterized by kneading this mixed material in a drum washer.