JP2651799B2 - Method for producing ettringite powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing ettringite powder, and more particularly, to a method for drying a ettringite powder suitable for transportation and storage, wherein filtration of a reaction mother liquor and drying of a produced powder are easy. The present invention relates to a method for easily and reliably manufacturing.

[0002]

BACKGROUND OF THE INVENTION Ettringite is, for example, a coating material for papermaking, an additive such as a filler or a fire-resistant lightweight board,
It is used as flame retardant paper, land improvement material, carrier for agricultural chemicals, etc., but it is not only fine crystals but also has a hydrophilic surface, which makes it difficult to separate from the mother liquor at the time of production, making filtration and separation difficult. For this reason, the ettringite is usually in the form of a hydrated paste, and therefore, there has been a problem that conventional ettringite is extremely inconvenient in handling various kinds including transportation and storage.

[0003]

DISCLOSURE OF THE INVENTION The present invention was developed to solve the above-mentioned problems, and is intended to provide ettringite powder which is easy to wash and dry and has a high purity and a uniform particle diameter. It is an object of the present invention to provide a method that can be manufactured in a dry state that is easy to handle.

[0004]

Means for Solving the Problems As a means for solving the above-mentioned problems and achieving the object, the present invention provides a method of mixing and stirring fine powder of lime aluminate with a saturated aqueous solution or a supersaturated aqueous solution of gypsum. , Etorinji together with to produce a fine columnar crystals of ettringite, the the fine columnar crystal partially aggregated and entangled to produce a fine secondary particles
A method for producing kite powder, wherein the mixing and stirring is performed with gypsum.
This is performed while circulating the aqueous solution, and
Adjust the volume and adjust the stirring method of the liquid and the strength of the stirring power.
And the addition rate of the fine powder of aluminate lime.
Controlled by the direct reaction of aluminate lime with water
Easy formation of hydrated amorphous material (lime aluminate hydrate)
Control, and the fineness of ettringite, a reaction product,
The fine columnar crystals are partially aggregated by the stirring action,
To form fine secondary particles by entangled like crystals
To improve the filterability of the reaction mother liquor and reduce the amount of ettringite.
Easy to separate and collect, easy to wash and dry
Ettringite powder with high purity and uniform particle size
Is provided in a dry state that is easy to handle .

[0005]

[Function] In the reaction between lime aluminate and a gypsum saturated or supersaturated aqueous solution, pay attention to the fact that the solubility of gypsum is not large, and always keep the reaction solution as a gypsum saturated solution or gypsum supersaturated solution. Add the appropriate amount of lime aluminate at the appropriate rate. In this case, lime aluminate is added to a portion of the gypsum reaction solution which is vigorously stirred to prevent sedimentation, so that the reaction between lime aluminate and gypsum is prioritized. The formation of acid lime hydrate (hydrous amorphous material) is suppressed.

On the other hand, partially agglomerating fine columnar crystals of ettringite, in order to generate the entangled allowed by fine secondary crystals, small vortex stirring the entire reaction mixture to allow many throughout in the reaction solution After the addition of the calculated amount of lime aluminate, the entire reaction solution should be agitated to equalize the completion of the reaction and the generation of secondary particles. It lasts several hours.

When all the operations are completed, the reaction solution is filtered to separate the formed ettringite, and after washing, 60 to 1
Dry at 00 ° C to obtain the product. The drying temperature can be set to 100 ° C. or higher depending on the purpose. By drying the ettringite powder, handling, such as transporting, storing, weighing, and packaging the product, is much easier than with conventional pasty ettringite. Further, the particle size of the secondary particles, the amount of water during the reaction is appropriately selected,
By adjusting the stirring conditions, they can be arbitrarily adjusted. Since the secondary particles have a chestnut cone shape, when the product of the present invention is added to various fibers or polymer resins, the entangled state is well and stably mixed, and the mixing yield is good, There is an effect that the function of the composite material using ettringite is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of the present invention will be described below with reference to the use of each device schematically shown in the accompanying drawings.

[0009] Example1 FIG. Is an embodiment of the present invention.1Of the equipment used in the
FIG. 2 is a schematic vertical sectional front view showing a volume of 10 liter
Reaction tank1And 8 liter capacity gypsum saturated aqueous solution adjustment tank
2And both tanks1as well as2Communicating with the bottom
Ip3And both tanks1as well as2Suitable for the tip
Large stirrer equipped with appropriate stirring blades4,5And the stirring
Machine4Reaction vessel on one side1Near the inner peripheral wall of the2
Side), a cylindrical body on the outer circumference6Homogeneous surrounding
Mixing mixer (homogeneous reaction mixer)7And one end adjusted tank
2And the other end is a raw material supply pipe.8Through on
Writing cylinder6Pump9With circulation pipe1
0And raw material supply pipe8Upper expansion section of8aArranged at the top of
Raw material supply mechanism11It is composed of

[0010] In Thus, Madzu purity of 98% of the alumina 7kg
And 15 kg of slaked lime (special grade) are mixed (Al ₂ O ₃ : Ca)
O: molecular ratio = 1: 3), water was added to form briquettes, and then 1
18 kg of lime aluminate heated at 350 ° C for 3 hours
And crushed with a dry ball mill (particle size: 100 mesh).
33 gr of aluminate lime fine powder , which has been passed through the entire surface, is prepared, and 35 gr of gypsum (purity: 93.8%) is added thereto and sufficiently ground and mixed.

[0011] Next, the reaction vessel 1 and the gypsum saturated solution adjustment tank 2
Put a total of 15 liters of water in the stirrer of adjustment tank 2
While rotating 5 , gypsum (dihydrate, purity 98.3%)
20 gr is added to the adjusting tank 2 and sufficiently stirred and mixed to prepare a saturated aqueous solution of gypsum. In this case, the pump 9 is operated,
Gypsum saturated solution circulation pipe 10 and the communication pipe 3 via the adjustment tank 2 allowed to circulate between the reaction vessel 1 and the conditioning tank 2.

[0012] Next, after the state of the agitator 5 is rotated in the reaction vessel stirrer 4 and homogenizing mixer 7 and the adjustment tank 2 in 1, material supply a mixed powder of the aluminate of lime and plaster From the mechanism 11 through the raw material supply tank 8 , the mixture was added in small portions to 7 parts of the homogenizing mixer. The addition rate was about 1.2 gr / min, and it took about 1 hour to add the whole amount. Circulation of gypsum saturated aqueous solution and reaction tank 1 after completion of addition
The stirring was continued for about 1.5 hours to complete the reaction.

[0013] After completion of the reaction, undissolved gypsum precipitated separated and the product dispersed suspended in the liquid was filtered collected, the product
Was confirmed to be ettringite by X-ray diffraction.
The yield was 89% of the calculated value. Also,
This ettringite partially aggregates fine columnar crystals
And formed in the form of entangled chestnut cone-shaped fine secondary particles
It has very good filtration and separation properties.
Was. In this example , the gypsum aqueous solution is mixed while circulating.
Since the stirring is performed, there is an advantage that the reaction can be completed in a remarkably short time as compared with the case where no circulation is performed.

[0014] Incidentally, when performing the above circulation type reaction process may be used an apparatus shown in FIG. 2 in place of the apparatus shown in FIG. That is, in the case of the apparatus shown in FIG. 2 , a plurality of baffle plates 12 are protruded at equal intervals on the inner wall of the reaction vessel 1 without using a homogenizing mixer, a cylindrical body, or the like. The raw material supply mechanism 11 is provided above the projecting portion of the baffle plate 12 and the other end of the circulation pipe 10 is connected to the reaction tank 1.
Although the device is different from the device used in the first embodiment in that the device is configured to be viewed from the inside, the same components are denoted by the same reference numerals because the other components are the same. Even with this apparatus, an ettringite product with good properties can be obtained in almost the same yield as in Example 1.

[0015] Example2 FIG. Is an embodiment of the present invention.2Of the equipment used in the
FIG. 2 is a schematic longitudinal sectional front view showing a device having a volume of 2000 liters.
Torr reactor13And gypsum saturation of 1500 liters volume
Aqueous solution adjustment tank14And the adjustment tank14Approaching outside
Raw material supply tankFifteenAnd the raw material supply tankFifteenAnd on
Reaction tank13Pump that communicates the inner bottom of the16Equipped
First circulation pipe17And the reaction tank13, Adjustment tank14Passing
And raw material supply tankFifteenInside each of the
Stirrer with each stirring blade18,19, 20And the reaction tank
13Near the inner peripheral wall of the14Side) and below it
End the first circulation pipe17Communication opening17near
A cylindrical body on the outer circumference21E surrounding the
Modifying mixer (homogeneous reaction mixer)22When,
Reaction tank13Top and adjustment tank14The inner bottom of the
2 circulation pipe23And the second circulation pipe23And react
Tank13Generated ettringai at the connection with
Filter for continuous filtration and collection24And on
Raw material supply tankFifteenRaw material supply mechanism located above25
And the adjustment tank14Feed the reflux liquid in the tankFifteenOver in
-Overflow pipe for flow26And the oh
Coarse gypsum powder separation network installed in the bar flow section27And from
Has been established.

The mixed powder of lime aluminate and gypsum used in this embodiment is substantially the same as that of the first embodiment,
What was mixed at a ratio of 1 gypsum per 1 mol of lime aluminate was used. The adjustment of the gypsum saturated aqueous solution in the adjusting tank 14 is substantially the same as that in the first embodiment.

First, a gypsum saturated aqueous solution adjusting tank 14 and a reaction tank
13 and the raw material supply tank 15 , water is added to the adjustment tank 14 while the stirrer 19 of the adjustment tank 14 is being rotated, and a slight excess of gypsum is always added to the adjustment tank 14, and the mixture is sufficiently stirred and mixed to constantly maintain a gypsum saturated aqueous solution of gypsum. Let it. During this case, the pump 16 is operated, the first circulation pipe 17 and the second the conditioning tank 14 gypsum saturated solution in the adjusting tank 14 through the circulation Paibu 23 of the material supply vessel 15 and the reaction vessel 13 And circulate.

Next, the reaction vessel 13 stirrer 20 and homogenizing mixer 22 and agitator 20 in the material supply vessel 15 in the even rotated, the raw material supply mechanism mixed powder of the aluminate of lime and gypsum in this state 25 to the raw material supply tank 15 . The addition speed of the gypsum saturated aqueous solution is adjusted by the rotation speed of the pump 16.
The flow rate varies depending on the flow rate of the mixture into the liquid, but when the flow rate is 60 liters / minute, the flow rate is about 140 gr / minute. As a result of performing the reaction while continuously circulating under these conditions, the production rate of ettringite is about 370 gr / Min, and the yield of ettringite was about 86%. The form and good characteristics were the same as in Example 1 .

In the case of this embodiment, the production of ettringite by the mixing and stirring reaction is carried out continuously with the circulation action, and the produced ettringite is collected one after another by the continuous filter 26. Therefore, there is a great advantage that the production efficiency of ettringite is further remarkably improved.

Further, an opening at the end of the first circulation pipe 17
17a is being臨設the bottom of the homogenizing mixer 22 which is disposed in the reaction vessel 13, lime saturated aqueous raw material mixture was mixed added homogenizing mixer 22
Since the liquid is supplied to the bottom suction port, a uniform reaction is efficiently performed by the mixer, and the liquid in the reaction tank 13 is constantly increased by the supply of the liquid to which the mixed raw material is added. From the reaction vessel 13 to the second circulation pipe 2
The ettringite contained in the overflow liquid is filtered and collected by the above-mentioned filter 24 , and is sent as a product to a post-process such as a drying process. Unreacted raw materials are collected at the bottom of the reaction tank 13 by the control of the specific gravity difference and the stirring method, further pulverized by the homogenizing mixer 22 , and circulated in the tank to perform a mixing reaction to produce ettringite. .

Although the main embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but can achieve the object of the present invention and do not depart from the gist of the present invention. Various design changes are possible.

[0022]

According to the present invention, a fine powder of lime aluminate and a saturated aqueous solution or a supersaturated aqueous solution of gypsum are mixed and stirred to react with each other, thereby producing fine columnar crystals of ettringite and partially dispersing the fine columnar crystals. Made of ettringite powder that aggregates and entangles to form fine secondary particles
Sintering method with fine powder of aluminate lime and gypsum
Mixing and stirring with aqueous solution or supersaturated aqueous solution
The method according to the present invention relates to a method for producing ettringite powder, which is carried out while circulating, so that ettringite excellent in separability from water can be produced with extremely high efficiency, and washing and drying in the subsequent steps are easy. Therefore, there is a great effect that ettringite powder having a high purity and a uniform particle diameter can be obtained in a dry and dry state that is easy to handle.

The secondary particles of the ettringite powder obtained according to the present invention have a chestnut cone shape as shown in the enlarged micrographs of FIG. 4 to FIG. In addition to contributing to the improvement of separability, dry powder ettringite has excellent mixing / dispersibility with other substances and molding / shape retention properties, and is therefore convenient to apply to various composite materials having special properties. There is.

That is, specifically, the ettringite powder obtained according to the present invention contains about 45% by weight of water (water of crystallization), and has a smooth, light powder form at room temperature. Various kinds of handling are easy,
Most of the water contained at 60 to 110 ° C. is vaporized and released. At that time, the heat of vaporization is taken away and the temperature is lowered.

Also, it is an inorganic substance, and after dehydration, about 1000
Since it has heat resistance that does not decompose even when heated to ℃,
It is effective to use heat-resistant and heat-insulating agents.

Further, even after once dehydrating by heating to 110 ° C., if it is left to cool as it is, it has the property of adsorbing water again and returning to the original water-containing state. Since about 0.8 gr of water is absorbed per 1 gr of ettringite powder, it is also effective as a drying and moisture proofing agent.

[Brief description of the drawings]

FIG. 1 is a simplified vertical sectional front view showing an example of an apparatus used in Embodiment 1 of the present invention.

FIG. 2 is a simplified vertical sectional front view showing another example of the device used in the first embodiment of the present invention.

FIG. 3 is a simplified vertical sectional front view showing an example of an apparatus used in Embodiment 2 of the present invention.

FIG. 4 shows the ettringite powder produced according to the present invention.
It is a microscope photograph of 200 times size which shows a columnar crystal.

FIG. 5 is a photomicrograph (× 1000 ) showing a columnar crystal of ettringite powder produced according to the present invention.

FIG. 6 is a 5000 × magnification micrograph showing columnar crystals of ettringite powder produced according to the present invention.

[Explanation of symbols]

1 reaction tank 2 gypsum saturated aqueous solution adjustment tank 3 communication pipe 4 stirrer 5 stirrer 6 cylinder 7 homogenizing mixer 8 raw material supply pipe 8a upper expanding part 9 pump 10 circulation pipe 11 raw material supply mechanism 12 baffle plate 13 reaction tank 14 gypsum saturated aqueous solution adjusting tank 15 raw material supply tank 16 pump 17 first circulation pipe 17a communication opening 18 stirrer 19 stirrer 20 stirrer 21 cylinder 22 homogenizing mixer 23 second circulation pipe 24 continuous filter 25 Raw material supply mechanism 26 Overflow pipe 27 Coarse gypsum powder separation net

Claims (2)

(57) [Claims] Claims: 1. A fine powder of lime aluminate and a saturated aqueous solution or a supersaturated aqueous solution of gypsum are mixed and reacted by stirring.
While generating fine columnar crystals of ettringite,
A method for producing ettringite powder in which the fine columnar crystals are partially aggregated and entangled to form fine secondary particles.
The lime aluminate powder and the saturated aqueous solution of gypsum
Mixing with supersaturated aqueous solution circulates gypsum aqueous solution
A method for producing ettringite powder, wherein the method is carried out while performing . 2. Mixing and stirring a fine powder of aluminate lime and a saturated aqueous solution or a supersaturated aqueous solution of gypsum to form an aqueous gypsum solution
The method for producing ettringite powder according to claim 1, wherein the method is performed while circulating and continuously performed.