JPH10167754A - Vitrifying material for solidifying waste and waste-solidified glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vitrifying material substantially not containing a substance evaporable on the vitrification of wastes, capable of being melted at a temperature of <=1400 deg.C, high in chemical durability and used for solidifying the wastes, and to obtain the waste-solidified glass. SOLUTION: This waste-solidified glass is obtained by adding vitrifying materials to incinerated ashes so as to give a composition comprising 35-48wt.% of SiO2 , 6-13wt.% of Al2 O3 , 6-20wt.% of Fe2 O3 , 3-7wt.% of MgO, 4-15wt.% of CaO, 2-5wt.% of ZnO, 0-5wt.% of TiO2 , 0-15wt.% of Na2 O, 0-15wt.% of K2 O, and 0-5wt.% of Li2 O, and further 2-25wt.% of (Na2 O+K2 O+Li2 O), 0-3wt.% of SO3 and 0-7wt.% of P2 O5 .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solidification glass for vitrifying incinerated ash (hereinafter simply referred to as incinerated ash) of low-level radioactive waste such as dried sewage sludge and concentrated waste liquid, waste solvent residue, and the like. The present invention relates to solidified waste glass obtained by vitrifying recycled material and incinerated ash.

[0002]

2. Description of the Related Art Conventionally, sewage sludge and low-level radioactive waste are added with glass-forming components and then added with glass-forming components in order to reduce the volume and prevent the release of contained heavy metal substances and radioactive substances. Had been transformed.

[0003] The vitrification of low-level radioactive substances is disclosed in JP-A-3-235098.
The technology disclosed in this publication is based on sodium nitrate (NaNO) in which a solvent cleaning waste liquid generated when cleaning a floor in a control area of a facility such as a nuclear power plant or an organic solvent with sodium carbonate or nitric acid is dried and granulated. ₃ ) And calcium pyrophosphate (Ca ₂ P ₂ O ₇ ), in which the waste solvent discharged from the solvent recovery equipment as a waste solvent residue is dry powder, is treated with Si.
By adding a vitrifying material such as O ₂ , Al ₂ O ₃ , B ₂ O ₃ , CaO, P ₂ O ₅ and vitrifying, low-temperature melting and improvement in the durability of the solidified product were achieved.

[0004] Regarding the treatment of sewage sludge, a glass-forming component has been added to the incinerated ash to produce crystallized glass that can be effectively used for materials such as building materials. This crystallized glass is
CaO was added to the incineration ash of sewage sludge and melted, and crystals such as anorthite and wollastonite were precipitated by heat treatment.

[0005]

B ₂ O ₃ and P ₂ O ₅ in the above-mentioned vitrified materials are usually added to a glass raw material in the form of boric acid or phosphoric acid, so that boric acid or phosphorus is added. by such acid is a chemical reaction, a B ₂ O ₃ and P ₂ O _5. However, boric acid and phosphoric acid are easily volatilized in the course of the reaction, and there has been a problem that the load of dust removal at the exhaust part of the furnace and the erosion power of the furnace increase. In addition, B ₂ O ₃ and P
Even when added as a glass raw material in the form of ₂ O ₅ , boron and phosphorus components were volatilized when the glass was melted, and the dust load and the erosion of the furnace occurred at the exhaust part of the furnace.

[0006] Next, in the production of crystallized glass, a high melting temperature of 1450 to 1500 ° C is required, and the melting equipment is large. Further, in order to stabilize the type and state of the precipitated crystals, it was necessary to finely adjust the added components with respect to the composition fluctuation of the incinerated ash.

Accordingly, the present invention has been made in view of the above circumstances, and when vitrifying incinerated ash or the like, it is possible to substantially eliminate volatile components and to melt at a temperature of 1400 ° C. or less, thereby improving chemical durability. An object of the present invention is to provide a high vitrification material for solidifying waste and a solidified waste glass.

[0008]

Means for Solving the Problems In order to solve the problems, the present invention provides a vitrifying material for solidifying waste, which vitrifies incinerated ash and the like, by mass%.
_{SiO 2 28~48%, Al 2 O} 3 1~16%, F
e ₂ O _{3 5 to} 26%, MgO 3 to 10%, CaO
3~20%, 0~6% ZnO, TiO 2 0~5%,
Na ₂ O 0-22%, K ₂ O 0-15%, Li ₂ O
0 to 5%, _{however, Na 2 O + K 2 O} + Li 2 O 3
-22%.

The reasons for limiting the glass composition of the vitrification material for solidifying waste will be described below. In addition, "%" of the composition used in this specification indicates% by mass.

[0010] SiO ₂ is a main component forming glass, and if its content is less than 28%, it is difficult to stably form glass, and phase separation and precipitation of coarse crystals are liable to occur in glass. The durability deteriorates. On the other hand, if it exceeds 48%, the viscosity of the glass increases, and it becomes difficult to melt at a temperature of 1400 ° C. or less.

Al ₂ O ₃ has the effect of improving chemical durability and suppressing phase separation. However, if it is less than 1%, its effect is not sufficient, and if it exceeds 16%, the viscosity of the glass increases and the melting property increases. Worsens.

Fe ₂ O ₃ acts as a flux and has the effect of lowering the melting temperature and improving the meltability without deteriorating the chemical durability. However, if it is less than 5%, the effect is not sufficient.
If it exceeds 6%, the glass becomes unstable and the chemical durability deteriorates.

MgO has the effect of improving the chemical durability and suppressing the phase separation and the precipitation of crystals. However, if it is less than 3%, the effect is not sufficient, and if it exceeds 10%, the glass becomes unstable. Become.

[0014] CaO has an effect of improving the chemical durability, but if it is less than 3%, the effect is not sufficient, and 20%
If it exceeds, precipitation of crystals tends to occur.

[0015] ZnO has an effect of improving chemical durability and suppressing phase separation and precipitation of crystals. Therefore, ZnO can be added up to 6%. However, if it exceeds 6%, precipitation of crystals tends to occur.

22% of Na ₂ O as an alkali component, K
The ₂ O 15%, if the Li ₂ O 5%, until, never deteriorate chemical durability. In addition, the total amount of these is 3%
If it is less than the above, the melting temperature cannot be lowered, and if it exceeds 22%, the chemical durability will be deteriorated.

According to a second aspect of the present invention, in the solidified waste glass, 35 to 48% of SiO ₂ ,
_{2 O 3 6~13%, Fe 2} O 3 6~20%, MgO
3-7%, CaO 4-15%, ZnO 2-5%, T
iO ₂ 0-5%, Na ₂ O 0-15%, K ₂ O 0
_{~15%, Li 2 O 0~5%} , however, Na ₂ O + K
₂ O + Li ₂ O 2 to 25%, SO ₃ 0 to 3%, P ₂
O ₅ was adjusted added glass-forming components such as 0-7% become so ash.

The reasons for limiting the glass composition of the waste solidified glass are described below. In addition, this glass composition also contains components mixed from incineration ash and the like.

[0019] SiO ₂ is a main component forming glass, and if its content is less than 35%, it is difficult to stably form a glass, and it is easy to cause phase separation and precipitation of coarse crystals in the glass. The durability deteriorates. On the other hand, if it exceeds 48%, the viscosity of the glass increases, and it becomes difficult to melt at a temperature of 1400 ° C. or lower.

Al ₂ O ₃ has the effect of improving the chemical durability and suppressing the phase separation. However, if it is less than 6%, the effect is not sufficient, and if it exceeds 13%, the viscosity of the glass increases, and
It becomes difficult to melt at a temperature of 400 ° C. or less.

Fe ₂ O ₃ acts as a flux and has the effect of lowering the melting temperature without deteriorating the chemical durability.
%, The effect is not sufficient, and it is difficult to melt at a temperature of 1400 ° C. or less. If it exceeds 20%, the glass becomes unstable and the chemical durability deteriorates.

MgO has the effect of improving the chemical durability and suppressing the phase separation and the precipitation of crystals. However, if it is less than 3%, its effect is not sufficient, and if it exceeds 7%, the glass becomes unstable. Become.

CaO has the effect of improving the chemical durability, but if it is less than 4%, the effect is not sufficient, and 15%
If it exceeds, precipitation of crystals tends to occur.

ZnO has the effect of improving the chemical durability and suppressing the phase separation and the precipitation of crystals. However, if it is less than 2%, the effect is not sufficient, and if it exceeds 5%, the precipitation of crystals tends to occur. .

TiO ₂ can be contained up to 6% without destabilizing the glass.

As an alkaline component, Na ₂ O is 15%, K
_{If the} content of ₂ O is up to 15% and the content of Li ₂ O is up to 5%, it can be contained without deteriorating the chemical durability. If the total amount of these alkali components is less than 2%, there is no effect of lowering the melting temperature, and if it exceeds 25%, the chemical durability is deteriorated. As a result, a stable glass can be obtained even if it contains an alkali metal component such as sodium nitrate obtained by drying the low-level radioactive liquid waste.

SO ₃ is a component mixed from incineration ash and the like. If the content increases, sodium sulfate is generated during glass melting and floats on the glass melt to generate an inhomogeneous portion. % Can be contained.

P ₂ O ₅ is a component mixed from incineration ash and the like, has an effect of lowering the melting temperature, and if contained in a small amount together with Al ₂ O ₃ , has an effect of improving the chemical durability. However, it tends to volatilize during melting, and its water resistance deteriorates due to an increase in the content. In order to reduce the burden on the melting furnace and the amount of volatilization during melting, the content is preferably up to 7%.

In addition to the above oxides, metal oxides such as MnO ₂ and Sb ₂ O ₃ contained in incinerated ash and the like are contained at 2% or less, respectively, and BaO, SrO, PbO and ZrO ₂ are respectively contained at 4% or less. You may.

As described above, by limiting the range of the glass composition, the vitrification material for solidifying waste substantially contains no volatile boron or phosphorus, so that the amount of smoke generated during melting is reduced. be able to. Further, it can be melted at a melting temperature of 1400 ° C. or less, and a material having excellent chemical durability can be obtained. Next, in solidified waste glass, the substance having volatility is substantially only a small amount of phosphorus mixed in from incineration ash, etc. The amount of smoke generated can be reduced. Further, it can be melted at a melting temperature of 1400 ° C. or less, and a material having excellent chemical durability can be obtained.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) This embodiment relates to a vitrifying material for solidifying wastes according to the present invention, in which 42% Si is used.
O ₂ , 14.5% Al ₂ O ₃ , 20% Fe ₂ O ₃ ,
5.5% MgO, 8% CaO, 4.5% ZnO,
4.5% Na ₂ O, 1% K ₂ O are mixed, and the melting temperature, the amount of smoke, the amount of attached volatiles, etc. when heating and melting in an electric melting furnace using a platinum crucible for 3 to 4 hours. evaluated. Further, the molten glass was homogenized and refined, and then a vitrified material for solidifying waste in the form of powder was obtained, and its water resistance was evaluated.

The electric melting furnace used in this embodiment had an opening at the top, and this opening was covered with a refractory such as a brick in order to evaluate the amount of smoke and the amount of attached volatiles. The water resistance of the glass is determined by reducing the mass of a glass powder having a size of 420 μm or more and 590 μm or less of a vitrification material for solidifying waste formed into a powder form after being immersed in boiling water for 60 minutes and dried. Is calculated as a weight loss rate. Next, smoke emission was observed from the time when the raw material of the platinum crucible started to melt until the raw material of the platinum crucible completely melted, and the smoke that passed through the gap of the refractory used as the lid material was observed.
The observation was performed by observing the surface of the refractory used as the lid material after melting.

(Evaluation Results) The glass composition of Embodiment 1 could be melted at 1350 ° C., and the vitrified material for solidifying the waste formed into a powder could be formed without devitrification. . The amount of smoke generated when the glass composition is melted depends on the amount of B ₂ O ₃ and P ₂ O in the glass composition as described above.
_{Since 5} was not substantially contained, it could be reduced to a very small amount. In addition, the amount of volatile matter attached to the lid member after melting is:
The amount of smoke was very small, and the volatile matter was hardly attached. Finally, the water resistance of the vitrified material for solidification of waste was evaluated using the Optical Glass Industry Association method as described above. As a result, the weight loss rate was 0.02%, and the material had excellent water resistance. .

(Embodiment 2) This embodiment relates to a solidified waste glass of the present invention, in which a glass-forming component and incineration ash are mixed in a ratio of 8: 2, and electric power is applied using a platinum crucible. The melting temperature, the amount of smoke generated, and the amount of attached volatiles were evaluated when heating and melting in a melting furnace for 3 to 4 hours. further,
The molten glass was homogenized and refined, then cast into a block and gradually cooled to obtain a solidified waste glass, and the water resistance was evaluated.

The glass forming component used in this embodiment is the powdered vitrifying material for solidifying the waste produced in the first embodiment, and the incinerated ash and the like are made of SiO ₂ , Al ₂ O ₃ ,
Fe ₂ O ₃ , CaO, P ₂ O ₅ , NaNO ₃ , Ca ₂ P
₂ O _{7 and the} like. The electric melting furnace had an opening at the top similarly to the first embodiment, and this opening was covered with a refractory such as a brick for evaluation of the examples. Further, the water resistance, smoke emission, and adhesion of volatile substances of the solidified waste glass were evaluated in the same manner as in the first embodiment.

(Evaluation Results) The mixture of the glass-forming component and incinerated ash of Embodiment 2 can be melted at 1380 ° C., and the solidified waste glass formed into a block can be formed without devitrification. I was able to. The amount of smoke generated when the mixture was melted could be suppressed to a small amount because only a small amount of P ₂ O ₅ in the waste was substantially contained as described above. The amount of volatiles attached to the lid member after melting was such that a small amount of smoke was generated, but the amount of volatiles attached could be reduced to an extremely small amount. Finally, the water resistance of the solidified waste glass was evaluated using the Optical Glass Industry Association method as described above. As a result, the weight loss rate was 0.02%, and the glass had excellent water resistance.

In the second embodiment, the vitrifying material for solidifying waste of the present invention is used as a glass forming component. However, the invention is not limited to this, and incineration ash and the like may be used. The same effect can be obtained by adding a glass-forming component to incinerated ash or the like so that the glass can be vitrified in the range described above. In the second embodiment, the mixing ratio between the glass forming component and the incinerated ash is set to 8: 2. However, the present invention is not limited to this, and the glass composition when the incinerated ash or the like is vitrified is described in claim 2. What is necessary is just to mix a glass forming component and incineration ash etc. so that the range of the invention made may be satisfied.

[0038]

【Example】

(Example 1) This example is similar to the first embodiment,
For the compositions described in Table 1 below, the melting temperature,
The devitrification, water resistance, amount of smoke emission, and amount of attached volatiles were evaluated. The first embodiment is described as “1” in Table 1.

[0039]

[Table 1]

As can be seen from Table 1, the vitrification material for solidifying waste of the present invention can be melted at a temperature of 1400 ° C. or less and contains substantially no B ₂ O ₃ and P ₂ O ₅ , so that the amount of smoke generated is Also, the adhesion amount of volatiles is extremely small and the water resistance is excellent. Therefore, B ₂ O
_{Even if 3} and P ₂ O ₅ are contained, by adjusting the mixing ratio of the vitrification material for solidification of waste and incineration ash, it is possible to melt glass while suppressing smoke and volatilization, and to obtain glass with excellent water resistance. It can be manufactured.

Example 2 In this example, as in the case of the second embodiment, the solidified glass waste shown in Table 2 shown below was melted, devitrified, water-resistant, smoked, and volatile. The amount of adhesion was evaluated. The second embodiment is described as “1” in Table 2.

[0042]

[Table 2]

As can be seen from Table 2, the waste solidified glass of the present invention can be vitrified at a melting temperature of 1400 ° C. or less,
Since it does not substantially contain B ₂ O ₃ , the amount of smoke and the attachment of volatiles can be almost eliminated, and the water resistance is excellent. In addition, if the content of P ₂ O ₅ mixed from incinerated ash or the like is 7% or less, the amount of smoke generated can be reduced to a small amount, and the adhesion of volatile substances can be reduced to an extremely small amount.

Further, from Examples 4 and 5, it is possible to obtain a glass whose water resistance is not deteriorated even when an alkali component such as Na ₂ O is contained as a glass component up to 15%.

[0045]

The vitrification material for solidifying waste according to the present invention can be melted at a temperature of 1400 ° C. or less by using the above-mentioned composition. Also, by not substantially containing boron and phosphorus which are easily volatilized during melting, the amount of smoke generated during melting is reduced, and the load of dust removal and erosion at the exhaust part of the furnace can be reduced. Can have a long life.

The waste solidified glass of the present invention can completely vitrify incineration ash and the like together with the glass forming component at a melting temperature of 1400 ° C. or less by using the above composition. In addition, by reducing the amount of smoke generated during glass melting by reducing the amount of smoke generated when the glass is not substantially contained and containing phosphorus, which is easy to volatilize during melting, and reducing the load of dust removal at the exhaust part of the furnace. And erosion can be reduced, and the melting furnace can have a long life.

Claims (2)

[Claims] 1. A method according to claim 1, wherein 28% to 48% of SiO ₂ ,
l ₂ O _{3 1 to} 16%, Fe ₂ O _{3 5 to} 26%, Mg
O 3-10%, CaO 3-20%, ZnO 0-6
%, TiO ₂ 0-5%, Na ₂ O 0-22%, K ₂
O 0 to 15%, Li ₂ O 0 to 5%, provided that Na ₂
O + K ₂ O + Li ₂ contains O having 3 to 22%, waste solidifying vitrified material ash and characterized by vitrification. _2. 35% to 48% of SiO ₂ ,
_{l 2 O 3 6~13%, Fe} 2 O 3 6~20%, Mg
O 3-7%, CaO 4-15%, ZnO 2-5%,
TiO ₂ 0-5%, Na ₂ O 0-15%, K ₂ O
_{0~15%, Li 2 O 0~5%} , however, Na ₂ O +
K ₂ O + Li ₂ O 2 to 25%, SO ₃ 0 to 3%, P
₂ O ₅ 0 to 7% of the glass forming ingredients in addition such as incineration ash to be adjusted waste solidified glass.