JPS61155217A - Production of boron oxide - Google Patents

Abstract

PURPOSE:To economize the fuel cost in comparison with a conventional method and to enable the use of an inexpensive crucible by heating boric acid in a heated vessel from the outside part, discharging the foamy boron oxide which is swelled up in the specified temp. range to the outside of the vessel from the upper side of the vessel and collecting it. CONSTITUTION:Boric acid is introduced into a heating vessel 1 (e.g. made of stainless or ceramic) and the heating vessel 1 is heated with a heater 4. While boric acid in the vessel is dehydrated, it becomes a solution-like state at about 150-200 deg.C and furthermore becomes slightly viscous liquid body C in accompanying to the advance of the dehydration. When the water content reaches about <=10% (10-2%) and the temp. of liquid reaches about >=250 deg.C (250-450 deg.C), the above-mentioned liquid body C becomes the foamy bodies D and swelled up. The blowing-up foamy bodies D are discharged naturally and continuously from a takeout port 2 of the upper part of the vessel to collect them in a pan body 3 by continuing the heating so that the temp. is maintained at about 250-450 deg.C until the liquid body C is all evaporated.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for producing boron oxide from boric acid. %~98% (moisture content 10%~2%)
This invention relates to a method for producing boron oxide that takes advantage of its property of changing to a bubbling state between two positions.

(Prior Art) Boron oxide is usually produced by heating and dehydrating boric acid, and is also called boric anhydride.

When producing CFR boron by heating and dehydrating boric acid,
Content 85 as specified in J I 5K-8431-61
If you want to obtain boron oxide with a water content of about 159%, it is sufficient to heat boric acid to a temperature of around 230°C for a certain period of time, and the state of change of boric acid at this time is a slightly to viscous liquid. Therefore, it is easy to manufacture, and can be manufactured at a temperature as low as about 200° C. if a vacuum dehydration method is also used.

However, the content is more than 90%, therefore the water content flO%
Various problems are encountered when trying to obtain the following boron oxides.

In other words, in the process of boron oxide being transformed by thermal dehydration, boric acid first becomes a solution at 150°C to 200°C, and then becomes viscous as the dehydration progresses, resulting in a content of about 90% to 98% ( Moisture content (around 10% to 2%),
When the temperature is between 250° C. and 450° C. (there are some differences depending on the heating rate), a highly sticky foam is blown (a state in which it swells into a foam).

After that, the melting point of boron oxide (boric anhydride) (577℃)
As it approaches the point, it becomes molten again, and when it crosses the point, it melts into a viscous liquid like starch syrup or molten glass.

Boric acid has the above-mentioned properties, and when producing a chemical compound with a content of 90 or more (water content of less than 10 Boric acid is heated for a long time at a temperature of 577℃ or higher to melt it into a viscous liquid like starch syrup, and then poured out of the crucible into another container and cooled, or it can be poured into the crucible and left outside. A manufacturing method in which the material is cooled is generally adopted.

(Problems to be Solved by the Invention) According to the above-mentioned conventional technology, boron oxide with extremely high purity (content of 98% or more) can be obtained, but this production method has the following problems. ing.

(b) The conventional method involves melting boric acid in a bath until it becomes a viscous liquid like starch syrup. It is necessary to heat it. Therefore, manufacturing takes a long time and fuel costs increase.

(b) The work of taking out the melted product in the crucible is complicated.

(c) It is a well-known fact that boric acid and borates dissolve metal oxides at high temperatures.For this reason, if the material of the crucible is not carefully selected in the conventional method, impurities may be added to the product due to melting of the crucible. Contamination may occur, and problems may arise regarding the durability of the crucible. Therefore, conventionally,
Usually, a platinum crucible was used, so there was a problem with the local side.

(ii) Boron oxide can often be used at a content of 90% to 98% (water content of 10% to 5%), depending on the application, but as with conventional methods, it becomes a viscous liquid like starch syrup. When heated to 98% or more,
Therefore, there may be cases where unnecessary labor costs are incurred.

Therefore, the technical challenge of the present invention is to solve the problems (a) to (b) above.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides that boric acid is placed in a container and heated for dehydration.When the boric acid exceeds its melting point in the final stage, it becomes starch syrup. During the process of changing into a viscous liquid, the content is about 90% to 98X (water content LUX to 2'). ), we focused on the fact that it has the property of blowing up in the form of foam. It is collected by

That is, in the present invention, boric acid is placed in a heating container and heated from the outside of the container, and in the process in which the boric acid changes due to the heating and swells into a foam, the foam is heated from the upper side of the container. It is characterized by being sequentially discharged outside the container and collected.

(Function) When boric acid is placed in a heating container and heated from outside the container with a heat source such as a burner, the boric acid in the container dehydrates and becomes 150%
It becomes a solution at a temperature of ~200°C, and then becomes viscous as dehydration progresses, with a water content of 10% or less (10% to 2%) and a liquid temperature of about 250°C or higher (250°C or more).
℃~450℃) (However, there is a slight difference depending on the heating rate), the liquid material becomes foamy and swells. By continuing to heat the foam, it will blow up beyond the height of the container, so if an outlet is provided at the top of the container, it will spill out from the outlet and naturally flow out of the container. Since the foam is discharged quickly and continuously, the discharged foam can be collected with a suitable tray or the like.

This foam instantly solidifies as it cools.
Powdered boron oxide can be produced by appropriately crushing the solidified foam as required.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. The figure shows an example of the present invention, 1 is a heating container,
The container 1 is made of stainless steel, ceramic, or other heat-resistant material, and is formed into a cylindrical shape with a desired diameter and height. In this case, the material, size, shape, etc. of the container 1 can be changed arbitrarily. Reference numeral 2 denotes an outlet provided near the upper end of the opening of the container 1. The outlet 2 of the embodiment is constructed by cutting out the upper end of the container 1 in a concave shape and fixing a gutter body to the core.

In the embodiment, a device with one outlet 2 is shown, but the number of outlets 2 may be increased arbitrarily, and the structure of the outlet 2 may also be changed as needed. . Reference numeral 3 indicates a saucer body positioned at the bottom of the outlet 2, and 4 indicates a heater such as a burner, which is appropriately distributed and arranged so as to heat the entire side and bottom surface of the container 1. It's weird to set it up.

Although not shown in the drawings, a thermometer may be disposed at an appropriate location within the container 1 so that the temperature of the boric acid solution within the container 1 can be detected.

Next, to explain the manufacturing method of boron oxide, as shown in Figure 3 (a), the raw material boric acid A (powder, with a water content of about 43.7
%) is placed in a container 1 and the container 1 is heated by the heater 4, the boric acid in the container 1 is heated, and as time passes, the temperature rises rapidly and dehydration begins. And Hou rR
A dissolves in the liquid, and at a temperature of about 150°C to 200°C, it first becomes liquid B as shown in Figure 3 (b), and then as dehydration progresses, solution B becomes viscous in the liquid. 3 years old
As shown in the figure (c), it becomes a somewhat viscous solution C-shaped. Next, as the dehydration progresses further and the water content reaches 90% or higher, the water content reaches 10% or lower, and the liquid temperature reaches approximately 250°C or higher (however, there may be a slight deviation depending on the heating rate), the above solution C becomes As shown in the figure), it swells into a sticky foam and blows up into the next layer. This foamy state continues for eight summers at a temperature of about 240°C to 500°C. Therefore, the temperature of the molten gc in container 1 is set at 240°C to 500°C.
The temperature of the solution C in the container 1 is adjusted appropriately to maintain the temperature in the range of 250°C to 450°C.
Continue heating until it disappears. In this case, if the temperature of solution C becomes too high and exceeds the melting point (577°C), the foam disappears and EK melts into a viscous liquid like starch syrup, as shown in Figure 3 (e). .

As mentioned above, the liquid temperature is approximately 40°C to 500°C.
By maintaining the solution C in the container 1 at a certain level, the solution C in the container 1 gradually becomes foamy and blows up to the top of the container 1, and the foam overflows from the outlet 2 as shown in the figure and flows out of the container 1. The boron oxide is naturally and continuously discharged and hangs down, and is collected in the tray body 3, where boron oxide is obtained.

The water content of boron oxide produced by the above method is 10')6
The quality is about ~2%, and the degree of water content can be adjusted arbitrarily by adjusting the temperature of solution C in the range of about 240°C to 500°C (however, there may be slight differences depending on the heating rate). ).

Then, by appropriately crushing the captured foam, powdery boron oxide having a desired mesh can be obtained.

Next, the Oko diagram shows another embodiment of the present invention, and this embodiment is as follows:
During the process in which the foam E, which has been blown up in the form of foam and discharged from the outlet 2 at the top of the container 1 to the outside of the container 1 by the method of the embodiment, hangs down onto the tray body 3, the foam E Boron oxide is obtained by heating with direct flame using a heater 4a such as a burner.Other manufacturing steps are carried out by the same method as in the first embodiment, and the parts in the diagram with the same symbols as in Figure 17 are It shows the same component parts.

According to the method of this embodiment, the foam E is further dehydrated by being heated by the direct flame of the heater 4a, and by this heating and dehydration, it is melted into a viscous liquid like starch syrup and collected in the saucer body 3. be done.

Therefore, according to this example, it is possible to produce boron oxide having a water content of 29 or less.

(Effects) The method of the present invention is as explained above, and according to the present invention, the following effects can be expected.

(d) Since boric acid is collected by being discharged from the container in a foam form without being melted into starch syrup, the production time can be shortened compared to conventional methods.

(b) Since high-temperature heating unlike the conventional method is not required, the material of the heating container can be easily selected and fuel consumption can be greatly reduced.

(C) Since the foam can be naturally discharged out of the container, the product can be easily and quickly taken out.

(d) Since it is collected using a foam, the content is 90% or more.
Boron oxide of any quality within the range of about 98X (water content of about 10X to 2%) can be freely adjusted and efficiently produced.

[Brief explanation of drawings]

Figure 3 is a schematic longitudinal sectional view showing one embodiment of the method for producing boron oxide according to the present invention, and figure 3A shows another embodiment of the present invention.
fm schematic plan view, Figures 3 and 3 are explanatory diagrams showing changes in the state of boric acid placed in a container due to heat dehydration. 1... Heating container, 2... Outlet, 3.
...Saucer body, 4.4a... Heater, A.
...boric acid, D...foam. Patent Applicant Nihon Ruscut Co., Ltd.\r (a) (b) (c) (d) (e) C, D E Procedural Amendment February 72, 1985 1, Case Indication Percentage Request No. 59-276768 2. Name of the invention Method for manufacturing boron oxide 3. Relationship with the case of the person making the amendment Patent applicant address 3-5-3 Tokyo Parts Industry Representative
Tsubo 1) Kohei 4, Agent 5, Date of amendment order 6 Reference 6 Detailed explanation of the invention in Book I # 7, Amendment Okaya, il + Specification 3'2 Negative contradiction zu line Correct the "touch point" of "melting point".

Claims (1)

[Claims] (1) Boric acid is placed in a heating container and heated from the outside, and during the process in which the boric acid changes due to the heating and swells into a foam, the swollen foam is removed from the upper side of the container. A method for producing boron oxide, characterized by sequentially discharging and collecting it outside a container.