JP2014076908A - Calcined lime-containing baked product, its digested product and manufacturing method of calcined lime-containing baked product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a particulate and fine treated product containing lime as a main component high quality having small content of unreacted calcareous and having high hydration activity and specific surface area.SOLUTION: A treated product containing lime as a main component and having size of 5 mm or less is composed by a calcareous raw material of any one of limestone, hydrated lime and byproduct lime and a byproduct raw material as needed, and is sintered in a range of 400°C to 1200°C by a heat treatment device S equipped with a furnace core tube 10 for heating the treated product and a beater member subject arranged in the furnace core tube, of which a plurality arranged in line along a direction of a center axis Pa of the furnace core 10, and giving shock to the treated product by roll-moving an inner peripheral surface of the furnace core tube 10 by a rotation of the furnace core tube 10 to obtain a product containing CaO of 60 to 99 wt.%, carbonate (COconverted value) of 0.1 to 5 wt.%, AlOof 0.01 to 20 wt.%, SiOof 0.01 to 20 wt.% and having a hydration activity of 0.5 to 60 sec. and a BET specific surface area of 3 m/g or more.

Description

  The present invention relates to a calcined lime-containing calcined product obtained by calcining a processed product containing lime as a main component, a digested product thereof, and a method for producing the calcined lime-containing calcined product.

  In general, lime (limestone, quicklime, slaked lime, calcium carbonate) is used in various fields such as architecture / civil engineering, chemistry, papermaking, food, and environment.

  In the production process of these limes, various by-products mainly composed of calcareous materials, so-called by-product lime, are generated in various forms. For example, fine limestone / limestone powder generated during limestone crushing and refining processes, washing residue / dehydrated cake, fine dust / baked dust generated during the production of quicklime, and heavy / light calcium carbonate Examples include limestone powder, wet residue / dehydrated cake, wet residue / dehydrated cake generated in the manufacturing process of slaked lime, or calcareous process by-products generated in the manufacturing process of paper, sugar, and leather.

  Since fine lime and fine lime have problems in handling, their use is limited, and it is difficult to find a useful use particularly with fine lime of 1 mm or less. Furthermore, the by-product lime is not only fine and fine, but often contains inorganic and organic components other than calcareous, making it more difficult to effectively use. In addition, the cost for recycling these by-product lime is much higher than the cost of processing and producing a high-quality lime raw material, which is a barrier to effective use.

  As a method of using fine lime and fine lime, these can be calcined to obtain a calcined product containing quick lime, but in the existing vertical furnace (shaft kiln, vertical kiln), ventilation in the furnace must be ensured. In this respect, the minimum particle size of the raw material is usually required to be about 20 mm, and it is practically impossible to burn fine particles / fine lime in a vertical furnace.

  Conventionally, for example, a technique described in Japanese Patent Application Laid-Open No. 06-9263 (Patent Document 1) is known as a method for firing such fine particles and fine lime. In this method, fine crystalline, medium crystalline or higher limestone is pulverized, and the obtained limestone powder is formed into a predetermined size and then fired at 900 ° C. or higher.

  Conventionally, for example, a technique described in Japanese Patent Application Laid-Open No. 2009-114029 (Patent Document 2) is also known. This is a process of firing lime sludge mixed with washing sludge discharged in the process of washing the mined limestone and dust collected from the exhaust gas of the lime firing furnace. It has the granulation process which granulates the lime sludge after a process in a defined shape, and the baking process which bakes the granulated lime sludge. In the drying process, the moisture of the lime sludge is dried to 16% by weight or less, and in the firing process, a rotary kiln having a condition that the temperature of the raw material inlet is 650 ° C. or less is used.

Japanese Patent Laid-Open No. 06-9263 JP 2009-114029 A

By the way, in the former conventional baking method, although the baking means is not clear, there is a problem that the equipment cost is high and the manufacturing cost is high because the molding step of limestone powder is essential.
Further, in the latter conventional firing method, since a rotary kiln is used, a short pass of the product to be fired is likely to occur, and when the short pass occurs, decalcification is not sufficiently performed on the fired product. So-called unreacted lime remains, and there is a problem that the activity is insufficient and the quality is poor. Moreover, in this prior art, since the shaping | molding process of a lime sludge is essential, there also exists a problem that equipment cost is bulky and manufacturing cost is high. If lime sludge is put into a rotary kiln as it is without being formed, fine particles and fine lime are highly adherent and cause a problem that a coating is easily formed on the inner wall of the furnace during firing. Therefore, there is a problem in that it is difficult to directly process a processed product having a size of lime as a main component and having a size of 5 mm or less to obtain a high-quality quicklime-containing fired product.

  The present invention has been made in view of such problems, and fine particles and fine processed products having a lime-based size of 5 mm or less are directly fired by a heat treatment apparatus to avoid adhesion to the furnace. However, it has a low unreacted calcareous content, high quality calcinated calcined product with high hydration activity and specific surface area, and high quality with high reactivity and specific surface area that is its digestion product. It aims at providing the manufacturing method of the slaked lime and calcined lime containing baking products.

In order to achieve such an object, the calcined lime-containing calcined product of the present invention is a calcined lime-containing calcined product obtained by calcining a treated product having a lime-based size of 5 mm or less,
As said processed material, it comprises any one or more calcareous raw materials among limestone, slaked lime and byproduct lime, and auxiliary raw materials blended as necessary,
A furnace core tube for heating the processed material, and a plurality of rows are provided along the direction of the central axis of the furnace core tube provided in the furnace core tube, and the inner periphery of the furnace core tube is rotated by the rotation of the furnace core tube. The processed product is fired in a range of 400 ° C. to 1200 ° C. by a heat treatment apparatus including a beater member that rolls the surface and imparts an impact to the processed product.
While containing 60 to 99% by weight of CaO and 0.1 to 5% by weight of carbonate (CO ₂ equivalent value), the hydration activity was 0.5 to 60 seconds, and the BET specific surface area was 3 m ² / g or more. It is configured. The carbonate (CO ₂ equivalent value) means the content of CO ₂ contained in the target product, and is mainly derived from unreacted calcium carbonate.

Here, the hydration activity is a measure of hydration reactivity measured by the following method. As understood from the measurement method, the smaller the value, the higher the hydration activity. Is done.
1) Put 600 g of water at 20 ° C. into a heat insulating container (dewar bottle) equipped with a temperature measuring device, and put 150 g of a sample whose particle size is adjusted to 3.36 mm or less.
2) Continuously measure the digestion exothermic temperature with a temperature measuring device attached to the heat insulating container, and confirm the temperature when the exothermic temperature reaches the maximum.
3) Read the time when the temperature reaches 80% of the maximum exothermic temperature, and let this be the hydration activity.

In the present invention, preferably, it contains 70 to 99% by weight of CaO and 0.1 to 3% by weight of carbonate (CO ₂ equivalent), has a hydration activity of 0.5 to 30 seconds, and a BET specific surface area. 10 m ² / g or more.

If necessary, the Al ₂ O ₃ 0.01 to 20 wt%, has a configuration which contains SiO ₂ 0.01 to 20 wt%.

In the present invention, in addition to the calcareous raw material described above, an auxiliary raw material may be blended depending on the application of the product on the assumption that the chemical component of the calcined lime-containing fired product defined in the present invention is satisfied. . That is, when the calcined lime-containing fired product of the present invention is used as a refining agent for steelmaking, refining is performed when components such as aluminum oxide, silicon oxide, magnesium oxide, or an oxide containing an alkali metal having a function as a flux coexist. In order to improve the effect, it is reasonable from the viewpoint of simplifying the productization process, reducing the calorific value, and reducing the amount of generated CO ₂ to subject the auxiliary material containing these oxides to calcining and calcining. is there. As described above, the auxiliary raw material may be appropriately selected according to the purpose of use of the product, and is not particularly limited in its kind and properties, but when the calcined lime-containing fired product according to the present invention is used as a refining agent for steelmaking, for example. In addition, steel slag, coal ash, aluminum ash, paper sludge, etc. are recommended as auxiliary materials from the viewpoint of effective utilization of unused and difficult-to-use resources. In addition, when using the burned product containing quick lime of the present invention as it is or digested and containing slaked lime as an exhaust gas treatment agent, a certain amount of lime, which is the main target component, is secured. In addition, it is preferable to suppress the blending of the auxiliary materials.

In this invention, when processing a processed material, a processed material is supplied to a heat processing apparatus and baked. In this case, when the furnace core tube rotates, the beater member rotates in the same direction as the rotation direction of the furnace core tube to roll on the inner surface of the furnace core tube, and the processed material moves in the furnace core tube. At this time, the processed material is fine and fine having a size of 5 mm or less, and the processed material adheres to the inner peripheral surface of the furnace core tube and tries to stop, but the beater member is in the same direction as the rotation direction of the furnace core tube. Rotates and rolls on the inner surface of the furnace core tube to give an impact to the processed material. It is forced to leave the surface and dispersed. Therefore, the time for which the processed material contacts the inner surface of the furnace core tube is extremely short, and thus firing is reliably performed. In this calcination, the rotational speed of the furnace core tube, the heating temperature of the furnace core tube, the supply and exhaust of air are appropriately adjusted to obtain a desired calcined lime-containing fired product.
In other words, by limiting the firing furnace, firing method, and firing conditions, it is possible to stably fire fine / fine limestone, by-product limestone, or crystalline limestone that has been difficult to fire so far, and highly active quicklime. A contained fired product can be obtained.

  The firing temperature is appropriately set according to the properties of the calcareous raw material to be added. That is, when the calcareous raw material is only calcium hydroxide, a firing temperature of 400 to 800 ° C. is recommended. Moreover, when calcium carbonate is included in the calcareous raw material, the firing temperature is preferably 800 to 1200 ° C. The heat source for firing is not particularly limited and may be appropriately selected depending on the use situation. However, lime firing equipment, steel making equipment, or incineration equipment such as waste is close to the place of implementation of the present invention. If waste heat from these facilities can be used, it is preferable to use it as much as possible from the viewpoint of energy saving.

The quick lime-containing baked product of the present invention, a CaO 60 to 99 wt%, with containing 0.1 to 5% by weight of carbonate (CO ₂ conversion value), the hydration activity 0.5-60 seconds, Since the BET specific surface area is set to 3 m ² / g or more, the content of unreacted calcareous substance is small, and the characteristics such as high hydration activity and specific surface area are provided, which makes it extremely useful. In the conventional calcined lime-containing fired product, the activity and the decarboxylation rate are in a trade-off relationship, and as the activity is pursued, the residual CO ₂ increases, that is, the content of unreacted lime increases. . The present invention provides a calcined lime-containing fired product that breaks such a trade-off relationship and achieves both low residual CO ₂ , high hydration activity (short-term hydration activity value), and high specific surface area (high activity). did it.

And as needed, when using limestone as said calcareous raw material, it is set as the structure which uses crystalline limestone.
Thereby, although crystalline limestone has the characteristic of self-disintegrating and pulverizing in a baking process, in this invention, it exhibits an effect in baking of a fine raw material, and is produced | generated as a finer calcined lime containing baking product. As a result, the obtained calcined lime-containing fired product exhibits a high specific surface area, that is, a high hydration activity. In addition, fine crystalline limestone has little useful use and is often discarded. Therefore, the use of fine crystalline limestone is particularly recommended from the viewpoint of reducing the amount of waste and effectively using unused and difficult-to-use resources.

In addition, if by-product lime is used as the calcareous raw material, if necessary, any one of calcareous by-products generated during the production of limestone, calcium carbonate, quick lime, and slaked lime, and calcareous by-products generated from the lime utilization process. It is set as the structure which uses two or more.
These by-product limes have few useful uses and are often discarded. Therefore, the use of by-product lime is particularly recommended from the viewpoint of reducing the amount of waste and effectively using unused and difficult-to-use resources.

  And it is effective that hermetically sealed with a moisture-proof material. Sealing and packaging the obtained calcined lime-containing fired product with a moisture-proof material is a more effective measure for suppressing alteration. Although the moisture-proof material is not particularly limited, an aluminum foil film, an aluminum vapor-deposited film, an inorganic vapor-deposited film obtained by vapor-depositing silicon or aluminum oxide on a resin film, and the like are preferable because they have excellent moisture-proof properties. The calcined lime-containing fired product packaged with a moisture-proof material may be used after being unpacked and opened, or may be used in a packaged state. In particular, when using the calcined lime-containing fired product of the present invention as a refining agent for steelmaking, components constituting a highly moisture-proof packaging material, that is, aluminum and silicon / aluminum oxide, have a refining effect, so that the molten state remains in the molten state in the packaged state. It can be used such as throwing in. The same applies to the injection method, and a method is also recommended in which a package is produced in accordance with the injection equipment, and the package itself is injected into the molten steel by injection.

Furthermore, this invention exists in the slaked lime containing digested material obtained by digesting said calcined lime containing baked material. As described above, the calcined lime-containing fired product obtained in the present invention has a very high specific surface area. Therefore, a digested product obtained by digesting it, that is, a slaked lime-containing digested product, inevitably exhibits a high specific surface area. In general, slaked lime used for exhaust gas treatment is not simply digested with quick water, but with high specific surface area and high reactivity. Slaked lime. On the other hand, the calcined lime-containing fired product of the present invention has such a high reactivity that it functions as an exhaust gas treating agent by itself, and therefore, when digesting this, without using any additive In addition, slaked lime having a high specific surface area and high reactivity can be obtained only with water. Specifically, slaked lime having a high specific surface area of 20 to 50 m ² / g can be easily obtained, although it depends on the properties of the calcined lime-containing fired product used as a starting material.

In addition, the method for producing a calcined lime-containing calcined product of the present invention for producing the calcined lime-containing calcined product is the above heat treatment apparatus, which receives the processed product on the upstream side and is rotated around a central axis extending in a substantially horizontal direction. A furnace core tube that moves the product from the upstream side to the downstream side and discharges the processed material from a discharge port provided on the downstream side, and a plurality of rows are provided in the furnace core tube along the direction of the central axis of the furnace core tube And a beater member that rolls on the inner peripheral surface of the furnace core tube by the rotation of the furnace core tube to give an impact to the processed material, and a predetermined section upstream from the discharge port of the furnace core tube from the outside. Using a furnace core tube heating section to heat,
In the furnace core tube, air flowing from the upstream side to the downstream side is flown, and the firing temperature range of the processed material by heating in the furnace core tube heating unit is set to 800 ° C. to 1200 ° C., and the furnace core tube heating unit It is set as the structure which hold | maintained the heated processed material at 800 to 1200 degreeC in the said calcination temperature range until it reaches the said discharge port.

  As a result, in the furnace core tube, dehydration and decarboxylation reactions occur when the processed material containing lime as the main component is fired. The moisture and carbon dioxide generated during these reactions are exhausted from the downstream side by the air flow. Go. In this case, when the ventilation is in a direction opposite to the processed material (counterflow), the processed material tends to scatter to the upstream side of the processed material input side, and as a result, the product recovery rate tends to decrease. Since the air flowing from the upstream side to the downstream side is flowed into the furnace core tube, and the ventilation direction is the same direction (cocurrent flow) as the conveying direction of the processed material, the situation where the processed material is scattered to the upstream side is prevented. And the recovery rate can be improved.

On the other hand, in the furnace core tube, dehydration and decarboxylation reactions occur when firing lime-treated products, but the water and carbon dioxide generated during these reactions are "cocurrent" with the treated products. In addition, the water and carbon dioxide gas generated by the above reaction tends to be reabsorbed by the object to be fired as compared to counterflow. However, in the present invention, the treated product is held in the firing temperature range until the treated product fired in the furnace core tube reaches the discharge port. It is possible to suppress the occurrence of carbon dioxide reabsorption reaction.
As a result, it is possible to reduce the content of the unreacted processed material while avoiding the adhesion of the processed material to the furnace, and to obtain a high-quality excellent fired product and to improve the product recovery rate. it can.

  According to the present invention, a fine and fine processed product having a lime-based size of 5 mm or less is directly baked by a heat treatment apparatus, the content of unreacted calcareous material is small, and the high hydration activity and ratio A high-quality calcined lime-containing fired product having a surface area can be provided. Furthermore, the digested product of the calcined lime-containing fired product of the present invention can provide a high-quality and excellent slaked lime-containing digested product having high reactivity and specific surface area. Furthermore, while avoiding the adhesion of the treated product to the furnace, the content of the unreacted treated product can be reduced to obtain a high-quality fired product, and the product recovery rate can be improved. A method for producing a calcined lime-containing fired product can be provided.

It is a figure which shows an example of the heat processing apparatus for baking the quicklime containing baking products which concern on embodiment of this invention. It is the sectional view on the AA line in FIG. 1 which shows the heat processing apparatus for baking the quicklime containing baking products which concern on embodiment of this invention. It is sectional drawing which shows the principal part of the heat processing apparatus for baking the quicklime containing baking products which concern on embodiment of this invention. It is a table | surface figure which shows the baking raw material used in the Example and comparative example of this invention. It is a table | surface figure which shows the baking conditions of Examples 1-10 of this invention, the comparative examples 1-11, the condition of the adhesion of the to-be-fired thing in the furnace, the collection rate of a baked product, and the property of a baked product. It is a table | surface figure which shows the result of the moisture absorption test in the constant temperature and humidity of the quicklime containing baking products packaged with the packaging material according to Examples 11-12 and Comparative Examples 12-13 of the present invention. It is a table | surface figure which shows the property when it relates to Examples 13-14 and Comparative Examples 14-15 of this invention, and digests a quicklime containing baked material to make slaked lime.

Hereinafter, the calcined lime-containing fired product according to the embodiment of the present invention will be described with reference to the accompanying drawings.
The calcined lime-containing fired product according to the embodiment is obtained by firing a treated product having a size of lime as a main component and having a size of 5 mm or less.
As a processed material, any one or more calcareous materials among limestone, slaked lime, and byproduct lime having a size of 5 mm or less are used as essential materials. Here, the calcareous raw material does not limit the kind or properties of the calcareous raw material, and only the size is 5 mm or less.

  By-product lime refers to calcareous by-products generated during the manufacture of lime products and calcareous process by-products generated during the processing of various industrial products and foods, especially when manufacturing limestone, calcium carbonate, quicklime, and slaked lime. The calcareous by-products (fine limestone, limestone powder, calcined dust, water washing residue, dehydrated cake, wet residue, etc.) and the calcareous by-products derived from lime used for the purpose of sugar purification in the sugar making process are fine. In that respect, it is a particularly recommended byproduct lime.

  Further, crystalline limestone having a size of 5 mm or less is also suitable as a limestone raw material used in the present invention. Crystalline limestone has the characteristic of self-disintegrating and pulverizing in the firing process, because this characteristic matches the characteristics of a heat treatment apparatus described later that is effective for firing fine raw materials. These by-product lime or fine crystalline limestone has little useful use and is often discarded. Therefore, the use of by-product lime and fine crystalline limestone is particularly recommended from the viewpoint of reducing the amount of waste and effective utilization of unused and difficult-to-use resources.

Furthermore, in addition to the calcareous raw material, an auxiliary raw material may be blended depending on the use of the product on the assumption that the chemical component of the calcined lime-containing fired product defined in the present invention is satisfied. For example, when the calcined lime-containing fired product of the present invention is used as a refining agent for steelmaking, a refining effect is achieved when components such as aluminum oxide, silicon oxide, magnesium oxide, or an oxide containing an alkali metal having a function as a flux coexist. Therefore, it is reasonable to subject the auxiliary materials containing these oxides to calcining together with calcareous materials from the viewpoints of simplifying the production process, reducing the calorific value, and reducing the amount of CO ₂ generated. . In addition, when using the burned product containing quick lime of the present invention as it is or digested and containing slaked lime as an exhaust gas treatment agent, a certain amount of lime, which is the main target component, is secured. In addition, it is preferable to suppress the blending of the auxiliary materials. Thus, the auxiliary raw material may be appropriately selected according to the purpose of use of the product, and is not particularly limited in its type and properties, but the calcined lime-containing fired product according to the present invention is used as, for example, the above-described steel refining agent. When used, steel slag, coal ash, aluminum ash, paper sludge, etc. are recommended as auxiliary raw materials from the viewpoint of effective utilization of unused and difficult-to-use resources.

  Note that the calcareous raw material and the auxiliary raw material to be used for firing may be either in a dry state or in a wet state. Needless to say, from the viewpoint of heat consumption, the dry state is preferable, but the heat treatment apparatus described below is used for the treatment of the object to be treated on the inner wall of the furnace, which is a concern in drying and firing in a normal internal-heated rotary furnace or external-heated rotary furnace. Adhesion and coagulation of the processed product do not occur, so that it may be put into the furnace in a wet state. In other words, the drying step can be omitted by putting the water-washed / dehydrated cake generated in the limestone refining step into the heat treatment apparatus in a wet state.

  Furthermore, adding other additives in addition to the above-mentioned auxiliary materials does not hinder the present invention. In particular, combustible materials such as pulverized coal, waste plastic, heavy oil, and waste oil burn in the furnace and provide an effective amount of heat for the dehydration and decarboxylation reactions of the material to be baked. This is useful as a measure to suppress it.

  In addition, as will be described later, the calcined lime-containing fired product of the present invention is directed to high hydration activity, high specific surface area, that is, high activity, but does not require activity, in other words, civil engineering / architecture applications that require hard firing. When the calcined lime-containing fired product of the present invention is applied to agricultural or agricultural applications, the specific surface area (activity of the calcined lime-containing calcined product obtained by selecting the quality of calcareous raw materials or adjusting the amount of auxiliary raw materials is adjusted. ) May be controlled. That is, it is possible to actively utilize difficult-to-use low-grade lime (low-purity limestone), by-product lime, or by-product raw materials according to the purpose of use of the product.

The calcined lime-containing fired product according to the embodiment of the present invention is manufactured by a heat treatment apparatus. With this heat treatment apparatus, the treated product is fired in the range of 400 ° C. to 1200 ° C., CaO is 60 to 99% by weight, carbonate (CO ₂ conversion value) is 0.1 to 5% by weight, and Al ₂ O ₃ is 0%. A burned product containing quick lime containing 0.01 to 20% by weight, 0.01 to ₂₀ % by weight of SiO ₂ , a hydration activity of 0.5 to 60 seconds, and a BET specific surface area of 3 m ² / g or more.
Two types of heat treatment apparatuses are used: a co-current type heat treatment apparatus for flowing air in the furnace in the same direction as the treatment object, and a countercurrent heat treatment apparatus for flowing air in the furnace in the opposite direction to the treatment object. It is done.

  1 to 3 show a cocurrent type heat treatment apparatus S for carrying out the manufacturing method according to the embodiment of the present invention. This includes a processed product supply unit 1 for supplying a processed product W. The processed product supply unit 1 includes a hopper 2 that stores the processed product W, and a screw conveyor 3 that conveys the processed product W in the hopper 2 to an upstream end side of a furnace core tube 10 to be described later. The screw conveyor 3 is driven via a transmission mechanism including a sprocket 5 and a chain 6 that are rotated by a motor 4.

  Further, the heat treatment apparatus S includes a furnace core tube 10. The furnace core tube 10 includes a supply port 10a that receives the processed product W supplied from the processed product supply unit 1 on the upstream side, and includes a discharge port 7 that discharges the processed product W on the downstream side, and extends in a substantially horizontal direction. The processed product W is rotated about the central axis Pa to move the processed product W from the upstream side to the downstream side, and the processed product is discharged from the discharge port 7. The supply port 10 a is configured at the upstream end of the furnace core tube 10. The downstream end of the furnace core tube 10 is configured as an exhaust port 10b for exhausting gas generated in the furnace core tube.

  Outer rings 11 are fixed to the upstream outer portion and the downstream outer portion of the furnace core tube 10, respectively. The outer ring 11 is supported by a roller 13 provided on a frame 12 provided on the installation floor surface, so that the furnace core tube 10 can be rotated via the roller 13 and the outer ring 11. . The furnace core tube 10 is supported while being inclined downward from the supply port 10a side to the exhaust port 10b side, and moves the workpiece W from the supply port 10a side to the exhaust port 10b side by rotation.

  As shown in FIG. 3, the discharge port 7 is provided in a wall portion of the furnace core tube 10 on the downstream side of a predetermined section heated by a furnace core tube heating unit 40 described later. More specifically, three discharge ports 7 are provided in an equiangular relationship between the downstream end portion of the heat retaining tube 42 of the furnace core tube heating unit 40 to be described later and the downstream outer ring 11. The furnace core tube 10 is made of heat-resistant steel containing nickel and chromium in order to improve heat resistance and increase durability.

  In the furnace core tube 10, a plurality of rows are provided along the direction of the central axis Pa of the furnace core tube 10, and the inner peripheral surface of the furnace core tube 10 is rolled by the rotation of the furnace core tube 10. A beater member 20 for applying an impact to W is provided. The beater member 20 is formed of the same material as the furnace core tube 10, has an axis Pb that is eccentric with respect to the center axis Pa of the furnace core tube 10, is provided radially around the axis Pb, and has an outer edge. Three or more (three in the embodiment) rectangular plate-shaped fins 21 that are in contact with the inner peripheral surface of the furnace core tube 10 are provided.

  As shown in FIG. 2, the fins 21 are integrally joined at one side edge so as to be equiangularly spaced, and a circle whose radius is the other side edge of the fin 21 from the center is formed on the core tube 10. It is set slightly smaller than a circle having a radius from the central axis to the inner peripheral surface. When the furnace core tube 10 rotates in the rotation direction R shown in FIG. 2, the beater member 20 falls down and rotates. Of the three fins 21, the other side edge of the two fins 21 is inside the furnace core tube 10. The remaining fins 21 are in contact with the peripheral surface and are upright in the internal space of the furnace core tube 10. As the furnace core tube 10 rotates, the two fins 21 that are in contact with the inner peripheral surface of the furnace core tube 10 also rotate along with the rotation of the one fin 21 that stands upright in the internal space due to its own weight. And one of the other two fins 21 separates from the inner peripheral surface and stands upright in the internal space. A stopper (not shown) is provided in front of the discharge port 7 of the furnace core tube 10 to restrict the movement of the beater member 20 located on the discharge port 7 side to the downstream side.

  Further, the heat treatment apparatus S includes a driving unit 30 that rotationally drives the furnace core tube 10. The drive unit 30 is stretched over a motor 31, a driving sprocket 32 rotated by the motor 31, a driven sprocket 33 provided outside the supply port 10 a of the furnace core tube 10, and the driving sprocket 32 and the driven sprocket 33. The transmission mechanism is composed of a chain 34.

  Furthermore, the heat treatment apparatus S includes a furnace core tube heating unit 40 that heats a predetermined section upstream from the outlet 7 of the furnace core tube 10 from the outside. The furnace core tube heating unit 40 includes a heat insulating tube 42 made of a heat insulating member provided on the gantry 41 and surrounding the furnace core tube 10, and a heater 43 provided inside the heat insulating tube 42 and heating the furnace core tube 10. Configured. The code | symbol 42a is the obstruction | occlusion wall which plugs up the edge part of a heat retention tube.

  Furthermore, the heat treatment apparatus S includes temperature holding means K that holds the processed product W heated by the furnace core tube heating unit 40 at a predetermined holding temperature until reaching the discharge port 7. The holding temperature held by the temperature holding means K is within the firing temperature range of the workpiece W by heating in the furnace core tube heating unit 40. The temperature holding means K includes a heat insulating material 46 that covers the wall portion of the furnace core tube 10 provided with the discharge port 7. The heat insulating material 46 is made of an appropriate material so that it can be maintained at the above holding temperature, passes through the downstream end of the heat insulating tube 42 of the furnace core tube heating unit 40, and reaches the outer ring 11 on the downstream side. The furnace core tube 10 is coated with a predetermined thickness. The upstream side of the heat insulating material 46 is provided so as to be slidably contacted with the closed wall 42 a of the heat insulating tube 42. As shown in FIG. 3, a through hole 47 having the same size as the discharge port 7 is formed in a portion corresponding to the discharge port 7 of the heat insulating material 46, and a metal tube 47 a is inserted into the through hole 47. Has been.

  Further, a hollow intermediate cover 48 that covers the furnace core tube 10 in which the discharge port 7 is formed is provided between the downstream end of the heat retaining tube 42 of the furnace core tube heating unit 40 and the outer ring 11 on the downstream side. Is provided. An outlet 49 is provided below the intermediate cover 48 to take out the processed product W discharged from the discharge port 7 of the furnace core tube 10. The take-out port 49 is provided with a valve (not shown) so that the processed product W can be taken out by a predetermined amount.

Furthermore, the heat treatment apparatus S includes an air supply unit 50 that supplies air from the upstream side to the downstream side in the furnace core tube 10. Specifically, in the heat treatment apparatus S, an upstream end cover 51 that covers the supply port 10 a while allowing the furnace core tube 10 to rotate and a downstream end cover 52 that covers the exhaust port 10 b of the furnace core tube 10 are provided. .
The upstream end cover 51 is provided with an air supply port 56 for supplying air into the furnace core tube 10, and the air supply unit 50 is configured to supply air from the air supply port 56. In the upstream end cover portion 51, the screw conveyor 3 of the processed product supply portion 1 is disposed so as to penetrate therethrough.
On the other hand, an exhaust outlet 53 for exhausting exhaust gas exhausted from the exhaust port 10 b of the furnace core tube 10 is provided at the upper part of the downstream end cover portion 52. An exhaust pipe (not shown) is connected to the exhaust outlet 53, and the exhaust is discharged to the outside air through, for example, a cyclone, a wet scrubber, a bag filter, and the like.

  Further, on the downstream side of the discharge port 7 of the furnace core tube 10, there is a spiral 57 that returns the processed material W that slides along the wall portion of the furnace core tube 10 and reaches the downstream side beyond the discharge port 7 to the discharge port 7 side. Is provided. The spiral 57 is fixed to the downstream end cover 52 via a shaft body 58. On the other hand, on the supply port 10a side of the furnace core tube 10, a spiral 59 for sending the received processed product W to the downstream side is provided. In the present embodiment, the spiral 57 is fixed to the downstream end cover portion 52 via the shaft body 58 so as to be in sliding contact with the wall portion of the furnace core tube 10, but is not necessarily limited thereto. Instead of being fixed to the shaft body, it may be directly fixed to the wall portion of the furnace core tube 10 by welding or the like, and may be appropriately changed.

  In the heat treatment apparatus S, the motor 4 of the processed product supply unit 1, the motor 31 of the drive unit 30, the heater 43 and the air supply unit 50 of the furnace core tube heating unit 40 are controlled, A controller 60 is provided for controlling the rotation of the furnace core tube 10, the temperature of the furnace core tube 10, and the temperature of the exhaust port 10b. The control part 60 is implement | achieved by functions, such as CPU of a computer, for example, and the baking temperature of the furnace core tube 10 is suitably set according to the property of the processed material thrown in. That is, when the calcareous raw material is only calcium hydroxide, a firing temperature of 400 to 800 ° C. is recommended. Moreover, when calcium carbonate is included in the calcareous raw material, the firing temperature is preferably 800 to 1200 ° C.

  In the embodiment, the control unit 60 sets the temperature in the furnace core tube 10 to 800 ° C. to 1200 ° C. In said setting, when calcium carbonate is contained in a calcareous raw material, if the temperature in the furnace core tube 10 is less than 800 degreeC, the thermal decomposition of the processed material W will become inadequate. When the temperature in the furnace core tube 10 exceeds 1200 ° C., high-temperature oxidation of the furnace core tube 10 proceeds, and the durability is significantly adversely affected. More desirably, the temperature in the furnace core tube 10 is set to 850 ° C to 1050 ° C.

  Therefore, when the workpiece W is processed in the cocurrent flow type heat treatment apparatus S according to the embodiment, it is as follows. The drive unit 30, the furnace core tube heating unit 40, and the air supply unit 50 are operated with the required setting by the control unit 60. Thereby, the furnace core tube 10 rotates, and the beater member 20 rotates in the same direction as the rotation direction of the furnace core tube 10 to roll the inner surface of the furnace core tube 10. And if the processed material W is supplied to the supply port 10a of the furnace core tube 10 from the processed material supply part 1, the processed material W will move gradually in the furnace core tube 10, and the processed material W will be heated in this movement. The By this heating, the processed product W is thermally decomposed, discharged as a burned lime-containing fired product from the discharge port 7 of the furnace core tube 10, and taken out from the outlet 54. In this case, on the downstream side of the discharge port 7 of the furnace core tube, a spiral 57 that returns the processed material W that slides along the wall of the furnace core tube 10 and reaches the downstream side beyond the discharge port 7 to the discharge port 7 side. Since it is provided, even if there is a processed product W that is about to reach the downstream side beyond the discharge port 7, the processed product W is returned to the discharge port 7 side from the spiral 57, so that it is surely discharged from the discharge port 7. Can do.

  During the heat treatment of the workpiece W, even if the workpiece W adheres to the inner peripheral surface of the furnace core tube 10 and stops, the beater member 20 rotates in the same direction as the rotation direction of the furnace core tube 10. Since the inner surface of the core tube 10 is rolled to give an impact to the processed product W, the processed product W which is attached to the inner peripheral surface of the furnace core tube 10 and is to be retained is caused by the impact to the inner periphery of the furnace core tube 10. It is forced to leave the surface and dispersed. In this case, since the beater member 20 includes the fins 21, when the beater member 20 rolls, the fins 21 collide with the workpiece W, so that the workpiece W is divided. The vibration can be imparted to and dispersed, and firing is reliably performed.

  Further, in the furnace core tube 10, when calcareous raw material and auxiliary raw material are fired, dehydration and decarboxylation reactions occur. Water and carbon dioxide gas generated during these reactions are discharged from the exhaust outlet 10 a and the exhaust outlet 53 by an air flow. It is exhausted. In this case, when the ventilation is in the opposite direction (counterflow) with the processed product W, the processed product W scatters on the upstream side of the processed product input side, and as a result, the product recovery rate tends to decrease. In this invention, since the ventilation direction was made into the same direction (parallel flow) as the conveyance direction of the processed material W, the situation where the processed material W scatters to an upstream side can be prevented. Therefore, the recovery rate can be improved.

Further, in the furnace core tube 10, when calcareous raw materials and auxiliary raw materials are baked, dehydration and decarboxylation reactions occur, and the moisture and carbon dioxide gas generated during these reactions are “cocurrent” with the processed material W. The water and carbon dioxide gas generated by the above reaction tends to be reabsorbed by the object to be fired as compared with the countercurrent, but in the embodiment, it is fired in the furnace core tube 10 by the temperature holding means K. Until the processed product W reaches the discharge port 7, the processed product W is held at a holding temperature within the firing temperature range. It is possible to suppress the occurrence of reabsorption reaction. That is, since the discharge port 7 and the surrounding temperature (outlet temperature) are maintained at 800 ° C. to 1200 ° C., the temperature becomes less than 800 ° C. at the front of the discharge port 7, and the carbon dioxide gas is reabsorbed in the processed product W. Can be prevented. In short, a situation in which a reaction of CaO + CO ₂ → CaCO ₃ occurs is prevented, and a situation in which the content of quicklime in the product is prevented.

In the embodiment, a countercurrent heat treatment apparatus (not shown) can be used. This is because the discharge port 7, the temperature holding means K, the intermediate cover 48, and the spiral 57 provided in the wall portion of the furnace core tube 10 are eliminated in the parallel flow type heat treatment apparatus S, and the discharge port is connected to the furnace core. Further, the air supply unit 50 is connected to an exhaust outlet 53 (configured as an air supply port) of the downstream end cover 52, and the air is supplied upstream from the downstream side. It is comprised so that it may send to the side and it may exhaust from the air supply port 56 (it is comprised as an exhaust outlet) of the upstream end cover part 51. Further, an outlet for taking out the processed product W discharged from the outlet 10 b of the furnace core tube 10 is provided at the lower part of the downstream end cover 52.
Also by this, it is possible to obtain a desired quicklime-containing fired product with the required setting by the control unit 60.

The calcined lime-containing fired product thus obtained has 60 to 99% by weight of CaO, 0.1 to 5% by weight of carbonate (CO ₂ equivalent), 0.01 to ₂₀ % by weight of Al ₂ O ₃ , It contains SiO _{2 in an amount} of 0.01 to 20% by weight, has a hydration activity of 0.5 to 60 seconds, and a BET specific surface area of 3 m ² / g or more. Preferably, it contains 70 to 99% by weight of CaO and 0.1 to 3% by weight of carbonate (CO ₂ equivalent value), has a hydration activity of 0.1 to 30 seconds, and a BET specific surface area of 10 m ² / g. That's it. The carbonate (CO ₂ equivalent value) means the content of CO ₂ contained in the target product, and is mainly derived from unreacted calcium carbonate.

Here, the hydration activity is a measure of the hydration reactivity measured by the following method. As understood from the measurement method, the smaller the value, the higher the hydration activity. The
1) Put 600 g of water at 20 ° C. into a heat insulating container (dewar bottle) equipped with a temperature measuring device, and put 150 g of a sample whose particle size is adjusted to 3.36 mm or less.
2) Continuously measure the digestion exothermic temperature with a temperature measuring device attached to the heat insulating container, and confirm the temperature when the exothermic temperature reaches the maximum.
3) Read the time when the temperature reaches 80% of the maximum exothermic temperature, and let this be the hydration activity.

This calcined lime-containing fired product has a CO ₂ content of 0.1 to 5% by weight, in other words, a low level of unreacted lime content, and at the same time hydrated. The main feature is that the activity is 0.5 to 60 seconds, the BET specific surface area is 3 m ² / g or more, and the high hydration activity and the specific surface area that are difficult to realize by the conventional firing method are specified. . Highly active quicklime is generally called soft calcined quicklime, and it is a manufacturing requirement to burn near the decarboxylation temperature in a short time. In order to satisfy this requirement, an internal-heat-type rotary furnace is currently suitable. However, as described above, the activity and the decarboxylation rate are in a trade-off relationship, and as the activity is pursued, the remaining CO _{2 is} increased. Usually, the content of unreacted lime increases. It was the quicklime-containing calcined product according to the present invention that broke such a trade-off relationship, with low residual CO ₂ , high hydration activity (short-term hydration activity value), and high specific surface area (high activity). It is possible to achieve both. Both of these values vary depending on the type and properties of the calcareous raw material used and the firing conditions, but it is a by-product lime with a calcium carbonate purity of around 90%, such as fine dust and wet residue generated in limestone mines. Even so, a calcined lime-containing fired product having a CO ₂ content of 0.1 to 3% by weight, a hydration activity of 0.5 to 30 seconds, and a BET specific surface area of 5 to ²⁰ m ² / g is obtained. When a fine calcareous raw material or crystalline limestone from which high activity is easily obtained is used as a raw material, the CO ₂ is 0.1 to 3% by weight, the hydration activity is within 10 seconds, and the BET specific surface area is 20 m ² / A calcined lime-containing fired product exceeding g can also be easily realized.

The rules for chemical components are as follows. First, the content of CaO is preferably as high as possible in order to maximize the function of quicklime, but the lower limit for achieving the function is 60% by weight. It is because the value as a calcareous product will be greatly impaired if less than this. The CO ₂ content is 0.1 to 5% by weight. The upper limit of the CO ₂ content is 5% by weight, which is the minimum condition for ensuring the product value as quicklime, and in that sense, it is preferably 3% by weight or less. The contents of Al ₂ O ₃ and SiO ₂ are both 0.01 to 20% by weight, and the values are set as appropriate according to the intended use of the product. That is, in applications where high-purity CaO is required, the contents of Al ₂ O ₃ and SiO ₂ must inevitably be low. For example, the calcined lime-containing fired product according to the present invention is used for steelmaking. When used as a refining agent, the content of Al ₂ O ₃ that functions as a flux and SiO ₂ is recommended to be 2 to 20% by weight. The method of adjusting the components of these Al ₂ O ₃ and SiO ₂ is not particularly specified, and if there is a shortage of content based on the chemical components of the calcareous raw material, use the auxiliary raw material as described above. Adjusting is also one way.

  Moreover, the quicklime containing baked product which concerns on another embodiment of this invention is carrying out the airtight packaging of the obtained quicklime containing baked product with a moisture-proof material, and is used as the package. Since it is hermetically packaged, it is effective for suppressing deterioration. Although the moisture-proof material is not particularly limited, an aluminum foil film, an aluminum vapor-deposited film, an inorganic vapor-deposited film obtained by vapor-depositing silicon or aluminum oxide on a resin film, and the like are preferable because they have excellent moisture permeability. The calcined lime-containing fired product packaged with a moisture-proof material may be used after being unpacked and opened, or may be used in a packaged state. In particular, the components constituting the packaging material having high moisture resistance, that is, aluminum and silicon / aluminum oxide have a refining effect. Therefore, when the burned material containing quick lime according to the present invention is used as a refining agent for steel making, the molten steel remains in the packaged state. Usage such as charging in is preferable. The same applies to the injection method, and a method is also recommended in which a package is produced in accordance with the injection equipment, and the package itself is injected into the molten steel by injection.

  In addition, when the quicklime-containing fired product of the present invention is used as a refining agent for steelmaking, it is not impeded to add other refining agents to the quicklime-containing fired product, but rather positive in enhancing the refining effect. It can be said that this should be adopted. Here, other refining agents are those generally used, such as steel slag, coal ash, fluorite, nepheline, calcium aluminate, calcium silicate, calcium aluminosilicate, aluminum ash, soda ash, Examples include serpentine, dolomite, metallic calcium, metallic magnesium, and calcium carbide. The use form of these refining agents is not particularly limited, but it is fine, previously mixed with the calcined lime-containing fired product of the present invention, or after mixing, a briquette machine, a uniaxial compression molding machine, etc. It is preferable to use it as a molded body because it is effective in improving the refining effect.

Furthermore, this invention exists in the slaked lime containing digested material obtained by digesting said calcined lime containing baked material. As described above, the calcined lime-containing fired product obtained in the present invention has a very high specific surface area. Therefore, a digested product obtained by digesting it, that is, a slaked lime-containing digested product, inevitably exhibits a high specific surface area. In general, slaked lime used for exhaust gas treatment is not simply digested with quick water, but with high specific surface area and high reactivity. Slaked lime. On the other hand, the calcined lime-containing fired product of the present invention has such a high reactivity that it functions as an exhaust gas treating agent by itself, and therefore, when digesting this, without using any additive In addition, slaked lime having a high specific surface area and high reactivity can be obtained only with water. Specifically, slaked lime having a high specific surface area of 20 to 50 m ² / g can be easily obtained, although it depends on the properties of the calcined lime-containing fired product used as a starting material.

Examples of the present invention will be described below together with comparative examples.
As the processed material, calcareous raw materials (A to G) shown in FIG. 4 were prepared.
In connection with Examples 1 to 10, as a heat treatment apparatus (also referred to as “radial furnace”), a “parallel flow” type experimental furnace similar to the heat treatment apparatus described above, and a “countercurrent” type experiment similar to the above. A furnace (with the outlet at the downstream end of the furnace core tube) was created. Each experimental furnace is of the electric heater type built in a furnace core tube having an inner diameter of 200 mm, an overall length of 4,000 mm, and an effective length (the length of the heating part) of 2,500 mm.
Further, according to Comparative Examples 1, 3, 4, 6, 8 and 11, an internal heating type rotary furnace having an inner diameter of 200 mm and a total length of 2,500 mm was prepared. Further, a rotary furnace (hereinafter referred to as “external heating type rotary furnace”) in which the beater member was removed from the counter-current heat treatment apparatus according to Comparative Examples 2, 5, and 7 was prepared.
In addition, in connection with Comparative Examples 9 to 10, in the above-mentioned “countercurrent” type experimental furnace (the discharge port is configured at the downstream end of the furnace core tube), a parallel flow type experimental furnace in which the air flow is simply reversed is also prepared. did.
In addition, as calcining furnaces for calcareous materials, there are standing furnaces such as Beckenbach furnace, Melz furnace, Koma type furnace, etc., but in order to ensure ventilation in the furnace, the size used in the present invention is 5 mm or less. The calcareous raw material cannot be fired. Therefore, in the comparative example, these standing furnaces were excluded, and the above-mentioned internal heat type rotary furnace and external heat type rotary furnace were used as firing furnaces.

A. Examples 1-7 and Comparative Examples 1-8
In Examples 1 to 7, the calcareous material shown in FIG. 4 was fired by the heat treatment apparatus.
Moreover, as Comparative Examples 1-8, the calcareous raw material of FIG. 4 was baked similarly to the Example by the internal heating type rotary furnace and the external heating type rotary furnace.
Firing conditions (feeding amount of raw materials, firing temperature, firing time), the state of adherence of the fired product in the furnace, recovery rate of the fired product, properties of the fired product (CaO content, Al ₂ O ₃ content, SiO ₂ content FIG. 5 shows the amount, CO ₂ content, hydration activity, and BET specific surface area.

In Example 1, Comparative Example 1, and Comparative Example 2, amorphous limestone having a size of 5 mm or less was used as a firing raw material. As can be seen from FIG. 5, in Example 1 using the heat treatment apparatus, there was almost no adhesion of the material to be fired to the inner wall of the furnace core tube, and the low CO ₂ content and high water content were stable. A calcined lime-containing fired product having a sum activity (short-term hydration activity value) and a high specific surface area could be obtained at a high recovery rate. On the other hand, in the internal heating type rotary furnace (Comparative Example 1), adherence of the material to be fired to the inner wall of the kiln was observed, and stable firing was inhibited. Moreover, the burning raw material of fine particles / fine powder of 3 mm or less was blown off by the combustion air to the raw material charging port (kiln bottom), and the product recovery rate was low. Furthermore, the obtained calcined lime-containing fired product had a high CO ₂ content, a low hydration activity, and a low specific surface area due to a short pass of the material to be fired. In addition, in the external heating rotary furnace (Comparative Example 2), the CO ₂ content, hydration activity, and specific surface area of the fired product are relatively good values. The adhesion of the fired product was increased, and stable firing was inhibited. As a result, compared with Example 1, the product recovery rate was reduced, and the increase in adhesion in the furnace forced the material feed amount to be significantly suppressed.

In Example 2, the same raw material was used, and the amount of feed was further increased compared to Example 1, and the residence time was shortened for firing. As a result, compared with Example 1, although the CO ₂ content was reduced and the hydration activity and the BET specific surface area were also reduced, the internal heating type rotary furnace (Comparative Example 1) and the external heating type rotary furnace (Comparative Example 2). ) Was a much higher quality calcined calcined product. Moreover, the stability at the time of baking was not different from Example 1, and showed a high product recovery rate.

  In Example 3, crystalline limestone having a size of 5 mm or less was used as the calcareous material. Although atomization due to self-disintegration occurred in the firing process, adhesion of the material to be fired in the furnace was not observed, but rather easy atomization improved by atomization, resulting in higher hydration compared to Example 1. An active, high specific surface area calcined lime-containing fired product could be obtained. On the other hand, in Comparative Example 3 using the same raw material, due to the atomization of the raw material in the firing process, the adherence of the material to be fired and scattering outside the furnace increased, and the recovery rate of the fired material was a comparative example. Further lower than 1.

  In Example 4, fine slaked lime was used as the calcareous material. Almost no adhesion within the furnace was observed, but the outside-furnace scattering of the fired product was increased by the ventilation of the furnace, and the recovery rate of the fired product was slightly reduced as compared with Examples 1 to 3. However, the specific surface area of the obtained calcined lime-containing fired product was extremely high. On the other hand, when the same raw material is baked in an internal heating type rotary furnace (Comparative Example 4), most of the baked material is scattered outside the furnace due to the influence of combustion gas, and the recovery rate of the baked material is extremely small. there were. Further, in the external heating type rotary furnace (Comparative Example 5), the adherence of the object to be fired in the furnace started immediately after firing, and the furnace was closed in a short time, and it was determined that firing was impossible.

In Example 5, recovered dust generated from a limestone mine was calcined as a calcareous material. As apparent from FIG. 5, no adhesion in the furnace was observed, and a calcined lime-containing fired product having a low CO ₂ content, a high hydration activity, and a high specific surface area could be stably obtained at a high recovery rate. On the other hand, in Comparative Example 6 in which the same raw material was fired in an internal heating type rotary furnace, the recovery rate of the fired product was extremely low due to scattering of the fired product by the combustion gas outside the furnace.

In Example 6, the byproduct lime generated from the sugar making process was used as the calcareous material. Since combustible organic substances are attached to the sugar production process by-products, these combustions were confirmed in the firing process, but there was almost no adhesion of the products to be fired to the inner wall of the furnace core tube, a low CO ₂ content, high A calcined calcined product having a hydration activity and a high specific surface area was obtained. Further, the combustion of the combustible organic material in the furnace reduced the load on the electric heater, and the calorific value was reduced by half compared to the previous examples. On the other hand, when the same raw material was fired in an externally heated rotary furnace (Comparative Example 7), the inside of the furnace was closed due to the adherence of the material to be fired, and it was determined that firing was impossible. This adhesion was more remarkable than that of Comparative Example 5, which was considered to be due to the combustion of combustible organic matter.

  In Example 7 and Comparative Example 8 (internally heated rotary furnace), as a calcareous raw material, a mixture of amorphous limestone used in Examples 1 and 2 and byproduct lime of sedimentation residue generated during slaked lime production is used. Using. The results follow the previous examples and comparative examples.

B. Examples 8 and 9 and Comparative Examples 9 and 10
In Example 8 and Comparative Example 9, amorphous limestone having a size of 5 mm or less was calcined as a calcareous material by a heat treatment apparatus in a cocurrent manner. As is clear from FIG. 5, in both Example 8 and Comparative Example 9, the adherence of the fired product to the inner wall of the furnace core tube during firing was not confirmed, and the recovery rate of the fired product was obtained by co-current firing. It was expensive. However, a large difference was confirmed in the properties of the fired product. That is, in Example 8 where the exit temperature of the fired product was set to 820 ° C., a calcined lime-containing fired product having a low CO ₂ content, a high hydration activity, and a high specific surface area was obtained, but the exit temperature was set to 600 ° C. In Comparative Example 9, the calcined lime-containing fired product obtained by the carbon dioxide reabsorption reaction, which was considered to have occurred during the cooling process of the fired material in the furnace core tube, had a high CO ₂ content and low hydration activity. The specific surface area was low.

In Example 9 and Comparative Example 10, recovered dust generated from a limestone mine was used as the calcareous raw material, and this was fired in a parallel flow system using a heat treatment apparatus. As a result, in both Example 9 and Comparative Example 10, the adherence of the material to be fired to the inner wall of the furnace core tube during firing was not confirmed, and the recovery rate of the fired material was high due to co-current firing. However, the properties of the fired product showed the same tendency as in Example 8 and Comparative Example 9, and in Example 9 where the exit temperature of the fired product was set to 900 ° C., the content of quick lime with a low CO ₂ content and a high specific surface area was contained. Although a fired product was obtained, Comparative Example 10 in which the outlet temperature was set to 500 ° C. had a high CO ₂ content, a low hydration activity, and a low specific surface area.

C. Example 10 and Comparative Example 11
In Example 10 and Comparative Example 11, byproduct lime (limestone mine dewatered cake) having a size of 5 mm or less was calcined as a calcareous material by a countercurrent system. In spite of containing Al ₂ O ₃ and SiO ₂ in addition to calcareous material, calcined lime-containing fired product having a relatively high hydration activity and BET specific surface area can be obtained at a high recovery rate of 89% in Example 10. It was. Furthermore, stable firing could be performed without forming deposits in the furnace during the firing process. On the other hand, in Comparative Example 11 using the internal heating type rotary furnace, most of the raw material was scattered on the raw material charging side, and as a result, the recovery rate of the fired product was as low as 8%. Also, during the firing process, fine powder material adhered to the inner wall of the rotary furnace, impeding stable firing. Furthermore, the hydration activity and BET specific surface area of the fired product were also low.

D. Examples 11-12 and Comparative Examples 12-13
In order to evaluate the effect of the packaging on the obtained calcined lime-containing fired product, a moisture absorption test of the specimen under constant temperature and humidity was performed. The test conditions are as follows.
Test raw material: calcined lime-containing fired product obtained in Example 1 (100 g)
Preparation of test specimen: Test environment in which the above-mentioned test raw materials are hermetically sealed by heat sealing using the packaging material shown in FIG. 6: 30 ° C., 90% RH
Test period: 30 days Measurement item: Weight change rate before and after the test

  The test results are shown in FIG. As is clear from FIG. 6, the specimen wrapped with the aluminum foil film, which is a moisture-proof material, and the aluminum vapor-deposited film showed almost no change in weight even after 30 days of testing. On the other hand, in Comparative Example 12 where no packaging was applied, an increase of 47% was confirmed. This is a result of the quick lime being transformed into calcium hydroxide and calcium carbonate by moisture and carbon dioxide present in the test environment. Further, in Comparative Example 13 packaged with a polyethylene film which is considered to have poor moisture resistance, a large increase was observed due to absorption of moisture and carbon dioxide.

E. Examples 13-14 and Comparative Examples 14-15
Subsequently, the calcined lime-containing fired product of the present invention was digested to examine the properties of the slaked lime-containing digested product. The slaked lime was digested while adding the same amount of water to the calcined lime-containing fired product in a stirred state with a high-speed shear mixer, and seemingly kept dry. The digested product was dried at 180 ° C., and this dried product was crushed on a 0.5 mm sieve, and the recovered sieve was used as a test material.

As shown in FIG. 7, the calcined lime-containing fired product obtained by firing amorphous limestone with a heat treatment device (Example 1), and the dehydrated cake generated from the limestone mining and processing steps are fired with a heat treatment device. Although the digested product (Examples 13 and 14) of the obtained calcined lime-containing fired product (Example 10) was digested only with water, alcohols and glycols at the time of digestion were 32 m ² / g and 48 m ² / g. It was a digested product having a high specific surface area equivalent to the high specific surface area slaked lime produced by adding a kind. This is nothing but the high specific surface area of the quicklime containing digest. On the other hand, in Comparative Example 14 and Comparative Example 15 in which the calcareous raw material was baked in an internal-heated rotary furnace and digested, the ratio as high as that of the example was caused by the specific surface area of the quicklime-containing digested material as a base. The surface area could not be obtained.

  As described above, by using the present invention composed of a firing furnace, a firing method, firing conditions, and the like, various fine and fine calcareous raw materials that have been difficult to fire so far can be stably and economically used. Can be fired. The fired product has high hydration activity and specific surface area, and can be effectively used in various fields. Furthermore, the digested product of the fired product also has a high specific surface area, and can be effectively used in various fields.

  The calcined lime product of the present invention can be effectively used in the fields of steel, chemistry, papermaking, architecture, civil engineering, and agriculture. The slaked lime-containing digested product of the present invention can be effectively used in fields such as architecture, civil engineering, agriculture, water purification, and exhaust gas purification.

S Heat Treatment Device W Processed Product 1 Processed Product Supply Unit 2 Hopper 3 Screw Conveyor 4 Motor 7 Discharge Port 10 Furnace Core Tube 10a Supply Port 10b Exhaust Port 11 Outer Ring 12 Base Frame 13 Roller 20 Beater Member 21 Fin 30 Drive Unit 31 Motor 32 Drive Sprocket 33 Followed sprocket 34 Chain 40 Furnace core tube heating part 41 Base 42 Heat insulation pipe 42a Blocking wall 43 Heater K Temperature holding means 46 Heat insulating material 48 Intermediate cover part 49 Outlet 50 Air supply part 51 One end cover part 52 Other end cover part 53 Exhaust outlet 56 Air supply port 57 Spiral 60 Control unit

Claims (7)

In the calcined lime-containing fired product obtained by firing a processed product having a size of lime as a main component of 5 mm or less,
As said processed material, it comprises any one or more calcareous raw materials among limestone, slaked lime and byproduct lime, and auxiliary raw materials blended as necessary,
A furnace core tube for heating the processed material, and a plurality of rows are provided along the direction of the central axis of the furnace core tube provided in the furnace core tube, and the inner periphery of the furnace core tube is rotated by the rotation of the furnace core tube. The processed product is fired in a range of 400 ° C. to 1200 ° C. by a heat treatment apparatus including a beater member that rolls the surface and imparts an impact to the processed product.
While containing 60 to 99% by weight of CaO and 0.1 to 5% by weight of carbonate (CO ₂ equivalent value), the hydration activity was 0.5 to 60 seconds, and the BET specific surface area was 3 m ² / g or more. A calcined lime-containing fired product. A burned product containing quicklime containing 0.01 to ₂₀ % by weight of Al ₂ O ₃ and 0.01 to 20% by weight of SiO ₂ .   3. When using limestone as the calcareous raw material, crystalline limestone is used.   When using by-product lime as the calcareous raw material, it is characterized by using any one or more of calcareous by-products generated during the production of limestone, calcium carbonate, quick lime and slaked lime, and calcareous by-products generated from the lime utilization process. The calcined lime-containing fired product according to any one of claims 1 to 3.   The calcined lime-containing fired product according to any one of claims 1 to 4, wherein the calcined product is sealed with a moisture-proof material.   The slaked lime containing digested material which digested the quicklime containing baked product in any one of the said Claim 1 thru | or 4. In the manufacturing method of the quicklime containing baking products which manufacture the quicklime containing baking products in any one of the said Claims 1 thru | or 4,
As the above heat treatment apparatus, the processed material is received on the upstream side and rotated about a central axis extending in a substantially horizontal direction, the processed material is moved from the upstream side to the downstream side, and the processed material is discharged from a discharge port provided on the downstream side. A plurality of rows of furnace core tubes arranged along the direction of the central axis of the furnace core tube and rolling the inner peripheral surface of the furnace core tube by the rotation of the furnace core tube Using a beater member that gives an impact to the processed material, and a furnace core tube heating unit that heats a predetermined section upstream from the discharge port of the furnace core tube from the outside,
In the furnace core tube, air flowing from the upstream side to the downstream side is flown, and the firing temperature range of the processed material by heating in the furnace core tube heating unit is set to 800 ° C. to 1200 ° C., and the furnace core tube heating unit A method for producing a calcined lime-containing calcined product, wherein the heated treated product is held at 800 ° C to 1200 ° C within the calcining temperature range until reaching the discharge port.

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