KR100249734B1 - Method of producing powdered calcium oxide - Google Patents

Abstract

In the present invention, a limestone powder having a particle size of 2 mm or less or limestone slab having a particle size of 2 mm or less is usually arranged in a furnace in a firing furnace maintained at an atmosphere in a furnace at a temperature of 825 ° C to 1,250 ° C. The raw material is stacked, and the pulverized lime manufacturing method characterized in that the pulverized discharge while stirring the powder raw material at a rotational speed of approximately 6 to 36 rpm by a plurality of stirrer blades attached to the stirrer.

Description

Method for manufacturing conidia lime

The present invention relates to a completely novel invention which makes it possible to make lime calcination in powder form impossible with any conventional kiln.

Conventionally, the calcining is not possible to fire as well as the efficiency is very low even if it is fired, the present invention is to achieve this, in particular limestone powder generated in the limestone mines, such as by-products from limestone or ironworks The sludge is not utilized as industrial wastes, and it is intended to be recycled into the present invention by focusing on causing pollution.

The present invention relates to a manufacturing method that can directly produce conidia lime with analytical lime, and more particularly, to a method for producing conidia lime that can be calcined all the raw materials such as analytical lime that requires firing.

Up to now, quicklime has been manufactured with rotary kiln or shaft furnace with calcined limestone in the back with fuel and good ventilation, but only when the raw material is lumped. It was possible. The reason for this is that in order to increase the firing efficiency, the air permeability should be good. However, according to the method of the present invention, all limestone raw materials requiring firing can be fired from agglomerates to powder phases having a particle size of 1 m / m or less, and more particularly, closer to a fine powder of 100 mesh or less. The efficiency is increased.

Conventionally, limestone sludge or dolomite sludge produced in steel mills has almost no disposal and is dumped in landfills. However, the present invention generally dries the powder raw material in order to recover and use it, without discarding it. After pre-treatment, the recovery and manufacturing using the kiln according to the present invention significantly reduces the heat source unit of the firing, and the manufacturing facilities can be installed in various sizes from large scale to small scale, so that the required construction cost is low, the product competitiveness is excellent, and high value-added products are It is to be created.

In order to calcify unanalyzed limestone, it must be pelletized and pelletized or imparted breathability to finely divided limestone. However, the former requires excessive time and cost, and when pelletizing itself is difficult and moist, its efficiency is high. There is a problem of deterioration, and in the latter case, a method and apparatus for imparting breathability to powder limestone and the like have not been devised until now.

Therefore, the present invention has been devised a combustion method and apparatus for firing, in particular, a firing product stirring method for imparting air permeability to a fired body, and is particularly characterized by good ventilation when powder particles are subjected to heat. That is, the powdery limestone raw material which is hardly breathable in producing powdery quicklime is also treated by stirring the powdery limestone or limestone sludge in a calcination furnace to impart breathability.

1 is a side view of the kiln according to the present invention

2 is a stirrer and a bottom view of the present invention;

<Code Description of Main Parts of Drawing>

DESCRIPTION OF SYMBOLS 1 Roche 2: Gas outlet 3: Body cover

4: Raw material inlet 5: Combustion device 6: Product outlet

7: Agitator (wing) 7 ': Agitator hook 8: Agitator central axis

9 driving reduction gear 10 support 11 furnace monitoring camera

12: temperature measuring device

The present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show a side view and a furnace bottom view as one embodiment of the firing furnace of the present invention.

The kiln according to the present invention shown in FIGS. 1 and 2 has a furnace 1 'of which is refractory, and an outer portion of the firing furnace is surrounded by a circular refractory, and the central axis of the stirrer 7 which hangs a plurality of hooks 7' vertically below the center of the furnace 1 is its central axis. It is fixed to the drive reducer 9 and the support 10 through 8. In the stirrer, a stirrer blade 7 is usually installed in a plurality of arcs of three or more as shown in FIG. 2.

Limestone powder and limestone sludge are put into the kiln according to the present invention of FIG. 1.

When limestone is chemically subjected to heat of about 825 ° C. or more, brief endothermic reaction occurs as follows, and quicklime is easily decarbonated to obtain quicklime.

That is, CaCO ₃ CaO + CO ₂ ↑

However, when the firing temperature is constant, the smaller the particle diameter of the limestone is, the larger the surface area ratio to receive heat, and the shorter the time required for heat to reach the core portion is shortened. Therefore, when the limestone particle size is set to 2 mm or less, At temperatures above 825 ° C, heat penetrates deeply into the deeper parts of the powder particles in an instant that is incomparable compared to calcite, and the CO ₂ gas is actively released to complete firing.

The most important thing in calcination of powdered limestone is whether the powder particles can be easily contacted with heat, and whether it can be fired uniformly, which is closely related to how to impart breathability to powdered limestone and the like.

The present invention carried out the following experiment to identify this.

<Example>

A firing furnace with a diameter of 1.000 mmø was fabricated, and the furnace atmosphere temperature was divided into 900 ° C, 950 ° C, 1000 ° C, 1050 ° C, and 1100 ° C by a combustion device, followed by heating. While maintaining the stirring state at agitation speed of 12 to 36 rpm while preliminarily weighing and loading it into a thickness of about 15 cm, it was discharged after a certain time to investigate the degree of calcination. Firing degree measurement method was determined by the degree of the amount of heat loss (Ig. Loss).

The experimental results were as follows.

As shown in Table 2, the pyrolysis temperature of limestone was theoretically different depending on the temperature distribution in the furnace and 825 ° C, but the firing took place at 900 ° C, but the firing was completed more time (compared to other high temperatures). The higher the furnace temperature, the faster the pyrolysis rate of limestone and the shorter the complete firing time. Ig here When the loss is more than 41.5%, it is confirmed that it is completely fired. In addition, as shown in Table 3, the required heat unit for complete firing according to the particle size was compared.

In the laboratory, the time limit for the passing of the calcining agent was determined from closing the Roche cover and starting the burner to starting the discharge after the input of raw materials. The fuel required for 5 minutes was 0.8 l of diesel fuel. In addition, the amount of calcined lime discharged was 60 kg.

It is completely calcined with a very small amount of heat required compared to a heat source unit used in a general soil furnace or a shaft furnace, so that the fuel consumption can be drastically reduced, and the cost of going through the grinding process to manufacture conventional powdered lime Will also save.

Properties of Limestone Powder Chemical composition Mouth dildo distribution CaO SiO ₂ MgO Fe ₂ O ₃ 50.3% 2.3% 0.8% 1.2% 0.5 m / m to 0.1 m / m 23% 0.1 m / m or less 77%

Plasticity with Temperature and Time (Ig. Loss Rate) Hourly 900 ℃ 950 ℃ 1000 ℃ 1050 ℃ 1100 ℃ 1 minute elapsed 11.5 12.8 14.02 19.4 19.9 2 minutes 19.3 28.2 32.2 38.3 41.7 3 minutes elapsed 25.8 38.0 41.6 41.5 41.8 4 minutes 34.5 40.5 41.5 41.4 41.5 5 minutes 38.0 41.6 41.6 41.5 41.7 6 minutes 41.7 41.5 41.6 41.4 41.7

Comparison of heat source units required for complete firing by particle size With use Limestone granularity Required heat source unit Plastic pass time Furnace temperature Fuel used Conventional firing furnace 30m / m-40m / m 980 ㎉ / ㎏.CaO About 5 hours 1100 ℃ Coal Present invention 0.5 m / m or less 129 ㎉ / ㎏.CaO 5 minutes 1000 ℃ Via

1 is a side view of the firing furnace of the present invention.

Here, when the powder limestone or limestone sludge is introduced into the raw material inlet 4 in the upper part of the furnace body, these powder raw materials are accumulated in the furnace. At this time, the atmosphere temperature in the furnace can be adjusted up to 20 ℃ ~ 2,500 ℃, but after long-term experiments in terms of firing degree, firing time, and other energy economic aspects, it was confirmed that the firing temperature was suitable for 825 ℃ ~ 1,250 ℃, preferably 1,050 ℃ ~ 1,150. It was found that the temperature of ℃ resulted in a relatively stable firing operation. When the firing temperature exceeds 825 ℃, the raw material causes the endothermic reaction, and when the temperature exceeds 1,250 ℃, it was found that excessive calcined portion and less calcined calcined portion were generated so that uniform calcining did not occur.

As described above, in the powder limestone raw material 13 placed on the agitator 7, the blade 7 of the agitator rotates in the direction of the arrow in FIG. 2 as the agitator shaft 8 rotates, thereby stirring the powder raw material. At this time, in consideration of the effective stirring and the temperature increase effect, it is preferable that the height of the furnace is not more than five times the height of the stirrer from the furnace (the furnace). It was found that the rotational speed of the stirring blade at this time is preferably 6 to 36 r.p.m. The rotation speed for this agitation is inversely proportional to the particle size. The rotation speed is adjusted according to the particle size and raw material properties, but when it is 36 r.p.m or more, the plasticity is reduced and the product exits to the outlet. In the center of the stirring blade 7, the central axis 8 is fixed vertically and connected to the reducer 9 to control the rotation speed. This stirrer is composed of a heat resistant, acid resistant material and can be used in a plurality of rows in the furnace. It is also effective for imparting uniform air permeability that can shorten the firing time.

As the calcination proceeds to the aforementioned temperature while stirring the limestone powder raw material, the generation of CO ₂ is activated and the CO ₂ is sucked out of the gas outlet 2. Of course, there is a filter outside the outlet 6 to filter out powdered or small powders.

In order to confirm the state of the above-described operation, the temperature measuring device 12 and the furnace monitoring camera 11 are installed in the firing furnace 1 as shown in FIG. 1.

The stirrer according to the present invention welds the hook 7 'to the stirrer 7 so that the calcined raw material such as limestone powder is in good contact with the heat in the furnace, and gives the arcuate curvature as shown in FIG. 2 so that the sintered product is concentrated in the intended direction. Character discharge is made easy. At this time, the degree of bending is adjusted so as not to be unbalanced, and the degree of bending is adjusted in consideration of the residence time and the degree of firing of the baked product. The number of agitator arms 7 is appropriately about 2 to 6, and the blades are installed so that the front and rear wings cross each other without progressing in the same course in the direction of rotation of the arm. Gives breathability to evenly.

On the other hand, the particle size of the limestone raw material powder is usually found to be a suitable raw material in the present invention, but when the particle size is too fine, it is scattered in the furnace, but there is a problem in the operation, if the powder of the normal particle size powder 2mm or less Almost no work problem was found. Needless to say, raw materials of 2 mm or more can be used, but the firing time is prolonged and the heat consumption is severe. Therefore, it has been found that a particle size of 2 mm or less is also good for work.

The fired product is drawn out through the product outlet 6 installed in the lower part. Of course, it can be opened and closed, and if necessary, the stirrer can be installed on any of the center of the furnace body from the wall of the furnace body by adjusting the forward direction, the degree of bending, and the like.

According to the present invention, both powdered limestone and limestone slag, which have been treated as industrial wastes and caused pollution problems, can be plasticized, thereby achieving various effects such as resource reduction, energy saving, and increased plastic efficiency.

Claims (1)

In a furnace in which a furnace maintained in an atmosphere of a furnace temperature of 825 ° C. to 1,250 ° C. is usually formed in a circular shape, a limestone powder or limestone slab having a particle size of 2 mm or less is usually placed on the furnace, and in the furnace provided with a stirrer rotatable thereon. Method for producing condensed lime, characterized in that by firing a plurality of stirrer blades and hooks attached to the stirrer at a rotational speed of approximately 6 to 36 rpm by firing the powder raw materials accumulated in the furnace through the outlet