JPH0716457A - Production of diatomaceous earth adsorbent and filler by fluidized layer burning method - Google Patents

Abstract

PURPOSE:To produce an adsorbent and a filler by subjecting the dry powder or the particlar starting material of a diatomaceous earth crude ore to a fluidized layer burning. CONSTITUTION:In the fluidized layer burning furnace 1, a heating device, such as an electric furnace 3, is installed so as to wind a pipy vessel 2 from the out side of the vessel 2. A gaseous nitrogen is injected into the inside of a starting material reservoir and the starting material is injected into the fluidized layer burning furnace 1 together with the starting material. A starting material layer is formed on the upper surface of the piston 5 moving in vertical direction. The gaseous nitrogen is injected into the furnace from the side face of the furnace or the upper face of the piston to fluidize the starting material. Then, the starting material burned at 500-1200 deg.C burning temp. and for 20-50sec is allowed to rise in the furnace and introduced into a cyclone classifying machine 6 from the upper end of the vessel, and a product is collected by a bag filter 7 and a coarse powder reservoir 8. Also, a multistage type or circulation type burning is attained by connecting the upper end of the classifying machine and the burning furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing an adsorbent and a filler powder by firing diatomaceous earth in a fluidized bed.

[0002]

2. Description of the Related Art Conventionally, diatomaceous earth raw materials are crushed and dried,
Sintered and refined powder or granules or lumps in a batch furnace, tunnel kiln, etc., then cooling and crushing,
After classification, it is packaged in bags and marketed as a filler powder such as a base material for lacquer ware. In this case, the firing process using a tunnel kiln in particular takes a long time, and it is difficult to shut off the air, adjust the temperature inside the furnace, and adjust the time of the heat load, and as a result, it was not possible to make detailed control of the product quality. . Therefore, the raw material after the firing step is still lumpy or granular, and it was necessary to pulverize and classify the raw material into fine particles.

On the other hand, there is a technique (Japanese Unexamined Patent Publication No. 62-156911) in which diatomaceous earth ore is crushed by an air jet mill and dried by a fluidized bed to remove mineral impurities, roast and cool. It has been developed. With this method, the purity and particle size distribution of diatomaceous earth can be improved in a shorter time compared to the conventional kiln firing.
A relatively uniform product in the range of 20 to 63 μm has become possible, but when grinding, classification, etc. are repeated after roasting, there is a disadvantage that the quality such as cake bulk density deteriorates.

Further, by injecting diatomaceous earth ore into a high temperature gas jet and maintaining the temperature of diatomaceous earth ore at about 1250 to 850 ° C. for several tens of milliseconds to several seconds in this gas jet. , A technique for obtaining a filter aid having good water permeability (Japanese Patent Application Laid-Open No. 4-22
No. 7008) has also been developed. In this method, firing is performed using a special furnace described in European Patent No. 0068853,
As a result, calcination and aggregation of diatomaceous earth raw materials can be controlled, and silica, which has a harmful effect on the human body when crystallized, can be maintained in an amorphous structure, and the calcined product is marketed as it is without crushing. Is described. However, special furnaces require complicated control, which greatly affects product quality and price.

[0005]

DISCLOSURE OF THE INVENTION The present invention uses a fluidized bed calcining furnace having a simple structure, shuts off air, shortens the calcining time, and enables fine adjustment of the temperature in the furnace. The risk of diatomaceous earth particle destruction is reduced by facilitating the control of firing conditions by adjusting the time in multiple stages and circulating the furnace, and enabling continuous discharge in powder form from the furnace. The purpose is to maintain the original particle shape.

[0006]

According to the present invention, a diatomaceous earth raw material is fluidized in a reducing atmosphere in a tubular fluidized bed firing furnace and then filled with medium particles, and the lower surface of the packed bed can be raised and lowered. A heating device that winds a firing furnace while supplying a fluidizing gas consisting of a reducing atmosphere from a plurality of side surfaces of the fluidized bed firing furnace, with or without forming a medium particle layer on the packed bed, supported by a flexible piston. The powdered or granular raw material is heated in the fluidized bed firing furnace together with the gas by 500 to 1200
A diatomaceous earth adsorbent / filler is produced by fluidized bed calcination by calcination at 20 ° C for 20 to 50 minutes. The medium particles have a particle size of 100 to 900 μm, more preferably 7
10-840 μm MS-C alumina is used.

Further, according to the present invention, the lower end of a fluidized bed firing furnace equipped with a vertically drivable piston on the lower surface is connected to a gas supply pipe, and the electric furnace as a heating device of the firing furnace is heated to a predetermined temperature. A fluidized bed of diatomaceous earth raw material was formed in the furnace while supplying nitrogen (N ₂ ) gas from the upper surface of the piston together with the side surface of the furnace. It is characterized in that the baked raw material is taken out. A gas furnace or other heating device can be used instead of the electric furnace.

The raw material discharged from the fluidized bed firing furnace can be sent to a classifier, and the coarse powder and fine powder can be returned to the fluidized bed firing furnace again. Further, the fluidized bed firing furnace used in the present invention is not limited to a single, for example, if a plurality of fluidized bed firing furnaces are arranged in series, the fluidized bed firing furnace can be operated in a multi-stage manner like the conventionally known multi-stage cyclone classifier. Can be combined with. It is also possible to improve the quality of the product after firing by attaching a cyclone classifier to each fluidized bed firing furnace.

[0009]

In the method according to the present invention, when the medium particles are used, they are filled in the middle part of the furnace, the raw material is supplied together with a reducing atmosphere gas such as nitrogen (N ₂ ), and then the heating device is heated to a predetermined temperature,
N ₂ gas is pressed into the furnace from the side surface of the furnace to cause a fluidized bed in the raw material in the furnace, and the fluidized bed is burned for 20 to 50 minutes. The vertical position of the fluidized bed can be adjusted by a piston that moves up and down in the furnace. The raw material taken out from the upper part of the firing furnace is introduced into a cyclone classifier, and the classified fine powder and particles are collected as products. When extending the firing time, the classified particles are returned to the furnace again and re-fired. By controlling the firing temperature, firing time, etc. by making the furnace multi-stage or connecting the fluidized bed furnace and the product classifier and circulating and firing, finally the shape of the raw material particles is maintained and the cake bulk density is small. Get the product.

[0010]

In particular, the method of the present invention has the following remarkable effects. 1. By using the fluidized bed, the firing time can be shortened as compared with the conventional tunnel kiln and the like. 2. Fine adjustment of the furnace temperature is possible. 3. The use of a reducing atmosphere gas for smoldering can be performed relatively easily, and high-quality products can be obtained at low cost by performing multi-stage or circulating firing.

[0011]

Example 1 As shown in FIG. 1, a fluidized bed firing furnace 1 used in the present invention is a tubular ceramics container 2 having an inner diameter of 40 mm and a length of 700 mm, and an electric furnace 3 having a length of 300 mm along the outer surface thereof. Is mounted so as to wind the container 2. The raw material supply reservoir 4 is connected is pressed tube of N ₂ gas, the raw material which is admixed with N ₂ gas is fed to the fluidized bed sintering furnace 1, forming a material layer on a piston 5 inserted from the bottom of the furnace To do. MS-C alumina particles of 710 to 840 μm are deposited in layers as medium particles on the raw material layer. The piston 5 rises quantitatively during firing. The N ₂ gas is supplied from a plurality of side surfaces of the fluidized bed firing furnace 1, and the firing is performed for 20 to 50 minutes while the N ₂ gas is also supplied from the upper surface of the piston. The fluidized and fired raw material is taken out from the upper part of the furnace 1, guided to a cyclone classifier 6, and a product is collected by a bag filter 7 and a coarse powder reservoir 8 for accumulating fine powder. When it is desired to extend the firing time, the fine powder accumulated in the back filter 7 and the coarse powder classified in the coarse powder reservoir 8 can be returned to the furnace again and re-fired.

The firing furnace 1 is heated to 1200 ° C. by the electric furnace 3. 100 g of dry diatomaceous earth powder (DE raw material) was supplied together with N ₂ gas at a gas flow rate of 20.3 cm ³ / sec, and when the raw material residence time in the furnace was set to 20 minutes, the product had a loss on drying, a loss on ignition, and a transmittance. Table 1 shows the cake bulk density, average particle size, and cristobalite content.

[Table 1]

[0013] Loss on drying is the 6th edition of the official standard for food additives (1992
, And dried at 105 ° C for 2 hours. Ignition loss was carried out by drying at 105 ° C for 2 hours in accordance with the 6th edition Officially designated Food Additives (1992), and then igniting at 1000 ° C for 30 minutes. The transmittance is a filtration performance index value obtained from the Darcy equation, and the larger this value, the better the permeability. The cake bulk density is the weight per unit volume obtained by the wet method, and the smaller the value, the better. The average particle size was determined by the laser method.
The cristobalite content was determined by the internal standard method using an X-ray diffractometer. These fired powders are black or grey-black, and the application can be considered as a base material for lacquer ware. Further, the purification treatment makes it possible to withstand the use of diatomaceous earth having the function of activated carbon as an adsorptive filter aid.

As a base material for lacquer ware, N ₂ gas stream fired powder was prepared to the same degree as other commercially available ground powders and used. The results are shown in Table 2. ⊚ indicates the best, ∘ indicates good, and Δ indicates slightly good.

[Table 2]

Further, the air flow calcined powder with N ₂ gas is activated to obtain a commercially available activated carbon or a commercially available diatomaceous earth product (hereinafter, commercially available D
Comparative test with the E product) resulted in the results shown in Table 3.

[Table 3]

[0016] Commercial products have a small specific surface area and have no various adsorption capacities, but the one obtained by gas stream burning is diatomaceous earth with adsorbability, though it is inferior to the commercially available activated carbon.

As shown in FIG. 2, a plurality of fluidized bed calcined layers are combined in a multi-stage manner. If the fluidized bed firing furnace is configured in this way, firing can be shared in each stage. In addition, a swirling flow occurs inside the furnace, and as with the conventionally known multi-stage cyclone classifier, it is possible to classify and classify by combining the air-flow layer firing furnaces in multiple stages, and the classified coarse and fine powders can be separated. By returning each to the firing furnace, the quality of the product after firing can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a fluidized bed firing furnace apparatus used in the method of the present invention.

FIG. 2 shows a combination of a plurality of fluidized bed firing layers used in the method of the present invention in a multi-stage manner.

[Explanation of symbols]

 1 Fluidized Bed Firing Furnace 2 Container 3 Electric Furnace 4 Raw Material Supply Reservoir 5 Piston 6 Cyclone Classifier 7 Bag Filter 8 Coarse Powder Reservoir

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[Procedure amendment]

[Submission date] August 31, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

According to the present invention, a diatomaceous earth raw material is supplied into a tubular fluidized bed calcining furnace by a reducing atmosphere gas, and the lower surface of the packed bed is supported by a vertically movable piston, and the packed bed is packed. With or without forming a medium particle layer on top of the fluidized bed firing furnace, while supplying a flowing gas consisting of a reducing atmosphere from a plurality of side surfaces of the fluidized bed firing furnace, it is heated by a heating device that winds the firing furnace to obtain powder or particles. A diatomaceous earth adsorbent / filler is produced by fluidized bed firing by firing the raw material together with gas in a fluidized bed firing furnace at 500 to 1200 ° C. for 20 to 50 minutes. The medium particles have a particle size of 100 to 90.
MS-C alumina of 0 μm, more preferably 710 to 840 μm is used.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

[0011]

Example 1 As shown in FIG. 1, a fluidized bed firing furnace 1 used in the present invention is a tubular ceramics container 2 having an inner diameter of 40 mm and a length of 700 mm, and an electric furnace 3 having a length of 300 mm along the outer surface thereof. Is mounted so as to wind the container 2. The raw material supply reservoir 4 is connected is pressed tube of N ₂ gas, the raw material which is admixed with N ₂ gas is fed to the fluidized bed sintering furnace 1, forming a material layer on a piston 5 inserted from the bottom of the furnace To do. MS-C alumina particles of 710 to 840 μm are deposited in layers as medium particles on the raw material layer. The piston 5 rises quantitatively during firing. N ₂ gas is supplied from a plurality of side surfaces of the fluidized bed firing furnace 1 and firing is performed for 20 to 50 minutes. The fluidized and fired raw material is taken out from the upper part of the furnace 1, guided to a cyclone classifier 6, and a product is collected by a bag filter 7 and a coarse powder reservoir 8 for accumulating fine powder. If you want to extend the firing time, fine powder and coarse powder reservoir 8 stored in back filter 7
Each of the coarse powders classified in step 1 can be returned to the furnace and refired.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

As a base material for lacquer ware, N ₂ gas fluidized fired powder was prepared to the same degree as other ground powders on the market and used, and the results shown in Table 2 were obtained. ⊚ indicates the best, ∘ indicates good, and Δ indicates slightly good.

[Table 2]

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Further, the fluidized-firing powder with N ₂ gas is activated to obtain commercial activated carbon and commercial diatomaceous earth products (hereinafter commercially available D
Comparative test with the E product) resulted in the results shown in Table 3.

[Table 3]

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The commercially available products have a small specific surface area and have no various adsorption capacities, but the one obtained by fluidized calcination is diatomaceous earth to which the adsorption capacities are imparted, although it is inferior to the commercially available activated carbon.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

As shown in FIG. 2, a plurality of fluidized bed calcined layers are combined in a multi-stage manner. If the fluidized bed firing furnace is configured in this way, firing can be shared in each stage. In addition, a swirling flow occurs inside the furnace, and like the conventionally known multi-stage cyclone classifier, a fluidized bed firing furnace can be combined in multiple stages to enable classification and classification, and to separate classified coarse powder and fine powder. By returning each to the firing furnace, the quality of the product after firing can be improved.

Claims (6)

[Claims] 1. A diatomaceous earth raw material is supplied into a tubular fluidized bed firing furnace by a reducing atmosphere gas, a lower surface of the packed bed is supported by a vertically movable piston, and a medium particle layer is formed on the packed bed. Without forming, the powder or granular raw material is heated inside the fluidized bed firing furnace by supplying the flowing gas consisting of the reducing atmosphere from multiple points on the side of the fluidized bed firing furnace and heating it by the heating device that winds the firing furnace. Together with 500-1200 ℃,
A method for producing a diatomaceous earth adsorbent / filler by fluidized bed firing, which comprises firing for 20 to 50 minutes. 2. The method for producing a diatomaceous earth adsorbent / filler according to claim 1, wherein the medium particles are alumina having a particle size of 100 to 900 μm. 3. A lower surface of a fluidized bed firing furnace equipped with a vertically drivable piston is connected to an air supply pipe to heat an electric furnace as a heating device of the firing furnace to a predetermined temperature, and a furnace side surface portion. At the same time, a fluidized bed of diatomaceous earth raw material is formed in the furnace while supplying nitrogen gas from the upper surface of the piston, and after firing for a predetermined time while gradually raising the piston, the raw material burned with the fluidized gas is taken out from the upper portion of the furnace. The method for producing a diatomaceous earth adsorbent / filler according to claim 1 or 2, characterized in that 4. The calcined raw material taken out from the upper part of the furnace together with the fluidized air is introduced into a cyclone classifier, and the product is collected in a bag filter and a tailing pool. A method for producing the diatomaceous earth adsorbent / filler described. 5. The method for producing a diatomaceous earth adsorbent / filler according to claim 1, wherein the fluidized bed firing furnace has a multi-stage structure. 6. The diatomaceous earth adsorbent according to claim 1, wherein the coarse powder and the fine powder particles are respectively returned to the fluidized bed firing furnace after the products in the fluidized bed firing furnace are classified. -Method of manufacturing the filler.