JPH10139466A - Production of cullet for glass raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat energy cost by a simple process and inexpensively obtain cullet by mixing trona ore with silica sand, calcining the mixture under prescribed conditions and heat melting the calcined material. SOLUTION: After trona ore prepared so as to have <=10mm particle diameter is mixed with silica sand or before the prepared trona ore is mixed with silica sand, calcination is carried out under oxygen-containing atmosphere at 500-900 deg.C for >=5min. Thereby, Na2 CO3 .NaHCO3 .2H2 O which is a main component of trona ore is decomposed and the produced CO2 and H2 O are scattered to form Na2 CO3 and an organic substances in impurities are removed by combustion. Thus calcined mixture of trona ore with silica sand is heated and melted. The mixture of trona ore with silica sand can be melted at relatively lower temperature for relative shorter heating time by mixing trona ore with silica sand in (45/55) to (30/70) weight ratio of Na2 O/SiO2 . The heating and melting temperature is normally >=1,000 deg.C and the temperature is 1,000 deg.C to 1,300 deg.C for 30-90min from the viewpoint of durability of a furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cullet used as one of glass raw materials, which can be produced from trona ore as a raw material in a simple process with good yield and reduced energy cost. It relates to a method for producing cullet.

[0002]

2. Description of the Related Art Glass is produced by blending raw materials so as to have a predetermined composition, melting and cooling.
Depending on the raw materials used and their composition, various types can be obtained. For example, the composition of soda-lime glass, which is the largest in production and use among glasses, is 65 to 75% by weight of silicon dioxide (SiO ₂ ) and aluminum oxide (Al ₂ O ₃ ) of 0.
5-4% by weight, calcium oxide (CaO) 5-15% by weight,
Magnesium oxide (MgO) 0.5 to 4 wt%, sodium oxide (Na ₂ O) 10~20% by weight, of iron oxide (Fe ₂ O _{3) 2} wt%
Consists of less than. This soda-lime glass is made of silica sand (SiO ₂ )
Feldspar (NaAlSi ₃ O ₈ ), soda ash (Na ₂ CO ₃ ), limestone (CaCO ₃ ) or dolomite (CaMg (C
O ₃ ) ₂ ), etc. are added, cullet, sodium sulfate, etc. are added, and the mixture is heated and melted.

[0003] Cullet, one of the above glass materials, is
It is necessary for facilitating melting of other raw materials, and is usually blended in a glass raw material in an amount of 20 to 50% by weight. As the cullet, waste glass that is cut off as an odd part during manufacture of a glass product or broken is used. However, since the amount of cullet used is large, waste glass generated in the glass production process alone is not enough to manufacture or purchase waste glass. The cullet does not need to be the same as the final glass composition, but only needs to be in a glass state.

On the other hand, as a method for producing soda ash, which is one of the glass raw materials, trona ore containing trona (Na ₂ CO ₃ .NaHCO ₃ .2H ₂ O) is crushed and heat-treated at 150 to 200 ° C. After that, a method of obtaining soda ash by dissolving in water, removing an insoluble component through a filter, evaporating and concentrating the obtained solution to crystallize, and then drying and crystallizing the crystals is known. ("NATURAL SODA ASH", Donald E. Garret
t, pp. 267-297, 1992) ".

According to the analysis data described in the above-mentioned document "NATURAL SODA ASH", trona ore is composed of Na ₂ CO ₃ .NaH
The main component is CO ₃ .2H ₂ O, but it contains about 10% by weight of a water-insoluble component as a main impurity. This insoluble component is SiO ₂ , CaO, MgO, CO ₂ , Al ₂ O ₃ , K ₂ O, Fe ₂ O
_3. It is composed of organic substances and others. Therefore, in the conventional method for producing soda ash from trona ore, it has been considered that it is an essential step to remove impurities by temporarily dissolving trona ore in water to remove insoluble components.

[0006]

As described above, cullet is indispensable as a raw material for glass.
Although used at a high ratio of 20 to 50% by weight in glass raw materials, there is a problem that it is expensive.

In addition, the above-mentioned conventional method for producing soda ash from trona ore requires a wet process of dissolving trona ore in water to remove insoluble components, and evaporating and concentrating to crystallize. The production efficiency is not always good, and energy costs such as crystallization and drying are required, and there is a problem that the insoluble component must be demudified.

Accordingly, an object of the present invention is to provide a method for producing a cullet for a glass raw material, in which cullet, which is one of the glass raw materials, can be produced in a simple process at low cost using trona ore as a raw material. It is in.

[0009]

Means for Solving the Problems The present inventors have found that all of the water-insoluble components contained in trona ore are not harmful as glass raw materials, and SiO ₂ , CaO, MgO, Al ₂ O
_3, K ₂ O, etc., paid attention to those which can be a component of the glass, by a direct raw material trona ore, intensive suspect that cheap to produce cullet for glass raw material in a more simple process As a result of research, after roasting trona ore to oxidize and remove organic substances, it was found that by heating and melting with silica sand, a cullet that could be sufficiently used as a glass raw material was obtained, and the present invention was completed. .

That is, a first aspect of the present invention is to mix trona ore prepared to a particle size of 10 mm or less with silica sand, and roast at 500 to 900 ° C. for 5 minutes or more in an oxygen-containing atmosphere, and then heat and melt. It is intended to provide a method for producing a cullet for a glass raw material characterized by the above.

A second aspect of the present invention is to prepare a trona ore prepared to a particle size of 10 mm or less at 500 to 900 ° C. in an oxygen-containing atmosphere at a temperature of 500 to 900 ° C.
It is intended to provide a method for producing a cullet for a glass raw material, which comprises roasting for at least one minute, mixing silica sand, and heating and melting.

In a third aspect of the present invention, in the first or second aspect, a mixing ratio of the trona ore and the silica sand is set to Na
An object of the present invention is to provide a method for producing a cullet for a glass raw material so that a weight ratio of ₂ O / SiO ₂ is 45/55 to 30/70.

A fourth aspect of the present invention provides the method for producing a cullet for glass raw material according to any one of the first to third aspects, wherein the roasting is performed in a fluidized state for 5 to 30 minutes.

According to a fifth aspect of the present invention, there is provided a method for producing a cullet for a glass raw material according to any one of the first to fourth aspects, wherein the roasting and heating and melting are continuously performed in a rotary kiln.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, before or after roasting the trona ore, the glass raw material to be prepared to have a particle diameter of 5 mm or less and to be subjected to iron removal treatment. The present invention provides a method of manufacturing a cullet.

According to the first and second aspects of the present invention, the particle size is 10 mm
After mixing silica sand with or before mixing silica sand with the prepared trona ore, in an oxygen-containing atmosphere, at 500 to 900 ° C.
In, by roasting or 5 minutes, decomposed main component is _{Na 2 CO 3 · NaHCO 3 ·} 2H 2 O of trona ore, and CO ₂ produced
H ₂ O is scattered to form Na ₂ CO ₃ , and the organic matter in the impurities is burned and removed. A cullet can be obtained by further increasing the temperature and melting the mixture of the roasted trona ore and silica sand while heating.

[0017] The organic matter is contained in large amounts in miscellaneous stones called oil shale. Since the amount of heat generated by the burning of the oil shale helps to raise and maintain the roasting temperature, the roasting is performed. It also saves energy by reducing fuel consumption.

The cullet thus obtained contains silicon dioxide (SiO ₂ ), which is a main component of silica sand, and sodium oxide (Na ₂ O) obtained from trona, which is a main component of trona ore. It is an impurity contained in ore
_{CaO, MgO, Al 2 O 3} , K 2 O, contains the Fe ₂ O ₃ or the like.

However, since CaO, MgO, Al ₂ O ₃ , and K ₂ O are essentially required as glass raw materials, there is no problem even if they are contained in cullet. Also, Fe ₂ O ₃ is
Although it has the effect of coloring glass, the cullet actually obtained is almost transparent, and even if glass is made from this cullet as a raw material, there is almost no coloring, and it can be used sufficiently depending on the application. . The reason for this is
The content of residual Fe ₂ O ₃ is not so large, and it is thought that coloring has a synergistic effect between Fe ₂ O ₃ and organic substances, and coloring can be sufficiently suppressed only by removing the organic substances among them It is supposed to be. In addition, when using as a raw material for glass with a small amount of iron which requires higher transparency, it can be dealt with by performing a later-described iron removal treatment.

As described above, it is possible to produce a cullet which can be used as a glass material without any trouble simply by roasting the trona ore at a predetermined temperature for a predetermined time or more, and heating and melting a mixture of the trona ore and silica sand. The production cost of raw material cullet can be greatly reduced.

According to the third aspect of the present invention, the mixing ratio of trona ore and silica sand is 45/55 to 30 by weight as Na ₂ O / SiO _2.
By setting the ratio to / 70, melting can be performed at a relatively low temperature and for a relatively short heating time, and energy costs can be reduced. In addition, when melted into cullet, there is no devitrification or deliquescence.

According to the fourth aspect of the present invention, the roasting is carried out in a fluidized state for 5 to 30 minutes, so that the organic matter in the trona ore is sufficiently burned out, and the roasting is performed more than necessary to waste energy. Can be prevented.

According to the fifth aspect of the present invention, by continuously performing roasting and heating and melting by a rotary kiln, energy loss is reduced and roasting and heating and melting are performed in one step.
Since the supply of the raw material can be performed one time and with one apparatus, the productivity can be improved.

According to the sixth aspect of the present invention, before or after roasting of the trona ore, the iron content which is one of the causes of coloring of the glass is adjusted by adjusting the particle size to 5 mm or less and removing the iron. Cullets of better quality can be produced with as little as possible.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as the trona ore, those commonly used as a raw material for soda ash can be used. The trona ore supplied as a raw material for soda ash is usually prepared to a certain particle size, so if the particle size is 10 mm or less at the stage of being obtained as a raw material, it can be used as it is. .
However, when the particle size is larger than the above-mentioned particle size at the raw material stage, it is used after being pulverized to a particle size of 10 mm or less, preferably 5 mm or less.

The trona ore is an ore containing trona (Na ₂ CO ₃ · NaHCO ₃ · 2H ₂ O), which is one of natural sodas, as a main component, and has deliquescent properties. yellow~
Translucent brown, but mixed with black to gray opaque miscellaneous stones. Most of these miscellaneous stones are made of oil shale which contains particularly large amounts of impurities such as iron and organic substances.

The trona ore is described in the above-mentioned document "NATURAL SODA AS
According to the analysis data described in Table 8-4 on page 272 of H ", the composition is as shown in Table 1.

[0028]

[Table 1] (In Table 1, trona, and Na ₂ CO _3, and NaHCO _3, the sum of the H ₂ O.)

The insoluble components are listed in Table 8 on the same page of the reference.
3 According to the analytical data in the right column, it consists of the components shown in Table 2.

[0030]

[Table 2]

In the conventional method for producing soda ash from trona ore, as described above, trona ore is dissolved in water to remove the insoluble components, thereby obtaining high-purity soda ash. However, among the insoluble components, SiO ₂ ,
_{CaO, MgO, Al 2 O 3} , K 2 O , etc., those originally obtained becomes a component of the glass. The present invention has been made with a view to obtaining a cullet that can be sufficiently used as a glass raw material by roasting trona ore to remove organic substances, and then heating and melting it with silica sand to form a cullet. is there.

The trona ore is used before or after roasting in order to reduce iron which causes glass coloring.
You may remove iron as needed. However, the iron removal treatment is not necessarily required when the content of Fe ₂ O ₃ in the trona ore used as a raw material is small. The iron removal treatment can be performed using, for example, a known magnetic ore separator after preparing the trona ore before or after roasting to a particle size of 5 mm or less. The deironing treatment may be performed before the roasting, but if it is performed after the roasting, iron sulfide in the trona ore changes to iron oxide and becomes easily magnetically adsorbed. Can be.

In the present invention, silica sand that is commonly used as a raw material for glass can be used. This silica sand generally contains silicon dioxide (SiO ₂ ) in an amount of 90% by weight or more, and also contains feldspar, zircon, magnetite and the like.

In the method for producing a cullet for a glass raw material according to the present invention, after mixing trona ore and silica sand, both may be roasted together, or after roasting only trona ore, silica sand may be mixed. You may. According to the former method, since the raw material can be supplied at one time, the workability is improved, and there is an advantage that roasting and heating and melting can be easily performed continuously by a rotary kiln or the like. In the latter, heat energy at the time of roasting can be reduced by first roasting only the trona ore. Further, by roasting, iron sulfide is changed to iron oxide, and iron removal by magnetic separation is facilitated.

The roasting is performed in an atmosphere containing oxygen such as air.
5 minutes or more at 500-900 ° C, preferably 5 minutes
Do for ~ 30 minutes. By roasting to such conditions, the decomposition of _{Na 2 CO 3 · NaHCO 3 ·} 2H 2 O in trona ore is scattered and generated CO ₂ and H ₂ O, the Na ₂ CO ₃ As they are formed, organic matter is burned off. As a result, the trona ore has anhydrous sodium carbonate (Na ₂ CO ₃ ) as a main component, and SiO ₂ , CaO, MgO, Al ₂ O ₃ , K ₂ O, and Fe ₂ O as trace components.
₃ and so on.

When the roasting temperature is lower than 500 ° C., undesired components as glass components, particularly organic matters, are not sufficiently removed by burning, and when the obtained cullet is used as a glass raw material, the glass is colored. This is not preferred. On the other hand, if the roasting temperature exceeds 900 ° C., the trona ore is melted, and the combustion of the organic matter inside is rather hindered, which is not preferable.

On the other hand, if the roasting time is less than 5 minutes in a fluidized state, the roasting is not sufficiently performed, and the organic substances cannot be sufficiently removed by burning. Although the roasting time may be long, the effect does not change even if it exceeds 30 minutes in a fluid state, which is economically disadvantageous. In the case of roasting in a stationary state, the roasting time is preferably set to about 60 to 90 minutes because the roasting time is less likely to come into contact with air than in the fluid state.

After mixing the trona ore with silica sand and roasting,
Alternatively, after the trona ore is roasted and mixed with silica sand, the trona ore and the silica sand are heated and melted. The temperature of heating and melting is
It is sufficient that the temperature is such that trona ore and quartz sand are melted.
It is sufficient if the temperature is 1000 ° C or higher, but in consideration of the saving of heat energy and the durability of the melting furnace, the temperature is 1000 to 1300 ° C and 30 to 90 ° C.
Minutes are preferred.

The mixing ratio of trona ore and silica sand is 45 wt% as Na ₂ O / SiO ₂ in the cullet finally obtained.
/ 55 to 30/70. If the ratio of Na ₂ O is higher than this ratio, that is, if the ratio of trona ore is higher, it is not preferable because when melted into cullet, it becomes devitrified and deliquescent. Further, when Na ₂ O is smaller than the above-mentioned ratio, that is, when the ratio of silica sand is large, the melting temperature becomes high, which is not preferable in terms of energy.

The apparatus for performing the above-mentioned roasting and heat melting is not particularly limited, and usually, an apparatus for roasting ore or melting glass can be used. And heating and melting can be continuously performed by one apparatus, which is preferable.

The cullet for a glass raw material produced by the method of the present invention can be used in the same manner as a cullet conventionally used as a glass raw material.

[0042]

【Example】

Test Example 1 (Melting test) Trona ore and quartz sand were converted into Na ₂ O / SiO ₂ at a weight ratio of 50 /
Formulated to be 50, 40/60, 30/70, 10
Heat and melt at 00 ° C, 1100 ° C, 1200 ° C, and 1300 ° C for 30 minutes. In the molten state, pour out onto a carbon sheet, slowly cool and solidify, then cut into 3cm x 3cm x 0.3cm samples. Using a microscope, the number of gravel (insoluble particles) per 1 cm ^{3 of} the sample was counted to determine the molten state.
We also saw devitrification and deliquescent.

The melting state was evaluated as ◎ assuming that the number of gravels per 1 cm ³ was 0 was completely melted, and evaluated that it was almost melted when the number of gravels was 5 to 6 (there is no problem as cullet). It was regarded as ○, and the one having 50 to 100 gravel was considered as unmelted, and was evaluated as ×. Also, devitrification,
Those with deliquescent are marked as △. These results are shown in FIG.

From the results shown in FIG. 1, it can be seen that when the heating time is 30 minutes, if the heating temperature is 1100 ° C. or more, almost any melting ratio is obtained. However, when the trona ore and silica sand are mixed in a weight ratio of 50/50 as Na ₂ O / SiO ₂ , even if they are melted, there is devitrification and deliquescence. It can be seen that the weight ratio of Na ₂ O / SiO ₂ should be 40/60 or 30/70.

Next, the trona ore and quartz sand were mixed with Na ₂ O / SiO ₂
As for the mixture obtained so that the weight ratio becomes 40/60 and 30/70, the heating temperature is set to 1000 ° C., and the heating time is set to 30 and 6
At 0 and 90 minutes, the molten state, devitrification, and deliquescent were examined in the same manner as described above. These results are shown in FIG.

From the results shown in FIG. 2, when the heating temperature is 1000 ° C., when the mixing ratio of trona ore and silica sand is 30/70 by weight as Na ₂ O / SiO ₂ , the mixing ratio is 90 minutes or more. But
When it is 40/60, it can be melted by heating for 60 minutes or more, and it can be seen that there is no devitrification or deliquescent.

Test Example 2 (Coloring test) Trona ore and quartz sand were converted to Na ₂ O / SiO ₂ at a weight ratio of 40 /
A to H shown in Table 3 for the mixture mixed to be 60
After the pretreatment, the cullet was heated and melted at 1100 ° C. for 30 minutes, and the color of the obtained cullet was observed. The roasting may be performed by using a crucible to stand still or in a fluidized state using a rotary kiln. Table 3 shows the results.

[0048]

[Table 3]

From the results shown in Table 3, as a pretreatment, B: a portion of black particulate matter was removed, D: roasting at 600 ° C. for 60 minutes, E: 70
After roasting at 0 ° C. for 60 minutes and F: roasting at 750 ° C. for 60 minutes, it was found that when heated and melted, it was colorless and transparent. When black particulate matter (black matter) is removed as a pretreatment, it becomes colorless and transparent, but this operation is quite difficult. If the temperature exceeds 1000 ° C., the trona ore begins to melt, and internal oxidation hardly proceeds, so that a favorable result was not obtained.

Example 1 A trona ore pulverized to 1 mm or less and quartz sand were mixed with Na ₂ O / SiO
_The mixture was mixed to give a weight ratio of 40/60 as ₂ . Then
Place the mixture in a crucible and allow to stand for 60 minutes in an air atmosphere.
After roasting at 0 ° C. for 60 minutes, it was heated and melted at 1100 ° C. for 30 minutes to obtain a cullet for a glass raw material.

Example 2 A cullet for a glass raw material was obtained in the same manner as in Example 1 except that roasting was performed in a rotary kiln in a fluidized state at 500 ° C. for 10 minutes.

Example 3 The procedure of Example 1 was repeated, except that the operation of grinding the commercially available trona ore having a size (particle diameter of 10 mm or less) to 1 mm or less was not performed. A raw material cullet was obtained.

Example 4 In Example 2, the same procedure as in Example 2 was repeated except that the commercially available trona ore having a size (particle diameter of 10 mm or less) was not ground to 1 mm or less. A raw material cullet was obtained.

Example 5 Trona ore pulverized to 1 mm or less was roasted at 600 ° C. for 60 minutes, and then subjected to magnetic iron ore to remove iron. Next, silica sand was mixed with this roasted trona ore in a weight ratio of 40/60 as Na ₂ O / SiO ₂ . Then the mixture is heated to 1100 ° C
For 30 minutes to obtain a glass material cullet.

Comparative Example 1 The procedure of Example 1 was repeated, except that the roasting temperature was changed to 400 ° C. (in a crucible for 60 minutes in a stationary state).
A cullet for a glass raw material was obtained.

Comparative Example 2 A cullet for a glass raw material was obtained in the same manner as in Example 2 except that the roasting temperature was changed to 400 ° C. (in a rotary kiln, in a fluidized state for 10 minutes).

Comparative Example 3 In Example 1, the mixing ratio of trona ore and silica sand was changed to Na
Instead of 30/70 by weight ratio as ₂ O / SiO ₂ without roasting,
A cullet for a glass raw material was obtained in the same manner as in Example 1 except that the heating and melting temperature was changed to 1200 ° C.

COMPARATIVE EXAMPLE 4 The procedure of Example 1 was repeated, except that roasting was not performed, and heating and melting were performed at 1000 ° C.
A cullet for a glass raw material was obtained in the same manner as in Example 1 except that the time was changed to 60 minutes.

Comparative Example 5 A cullet for a glass raw material was obtained in the same manner as in Example 1 except that the roasting was not performed.

Comparative Example 6 A cullet for a glass raw material was obtained in the same manner as in Example 1 except that the operation of pulverizing the trona ore to 1 mm or less was not performed and roasting was not performed.

Test Example 3 The cullets for glass raw materials obtained in Examples 1 to 4 and Comparative Examples 1 to 6 were examined for gravel (insoluble particles), coloring, devitrification, and deliquescent. Gravel was checked for the presence or absence of insoluble particles. In addition, as for coloring, those that were almost colorless and transparent were rated as ○, and those that were colored were rated as x. Furthermore, the devitrification was evaluated by examining whether or not crystals were precipitated from the once melted ones. The deliquescence was evaluated as カ when the cullet was not sticky and × when the cullet was sticky.

Table 4 shows the cullet for glass raw materials obtained in Examples 1 to 4 and Comparative Examples 1 to 6, silica sand, feldspar, dolomite, soda ash, and sodium sulfate. Glasses having the compositions shown were manufactured and subjected to a glass melting test.

[0063]

[Table 4]

In the glass melting test, 300 g of a raw material prepared so as to have a glass composition shown in Table 4 was put in a platinum crucible, melted at 1480 ° C. for 90 minutes in an air atmosphere, and then poured onto a carbon sheet. Take out, slowly cool, and solidify 5cm
A sample was cut out into a sample having a size of 5 cm x 0.3 cm, and the presence of gravel (insoluble particles), coloring, and presence of bubbles was confirmed. Those that did not exist were rated as ○, and those that did exist were rated as x. Table 5 shows the results.

[0065]

[Table 5]

From the results shown in Table 5, the trona ore of Examples 1 to 4 which were not pulverized to a size of 1 mm or less or which were not pulverized in a commercially available size (particle size of 10 mm or less) and silica sand were mixed with Na ₂ O. / S
iO ₂ was mixed at a weight ratio of 40/60 and roasted in a crucible at 600 ° C. for 60 minutes in a stationary state, or roasted in a rotary kiln at 500 ° C. for 10 minutes in a fluidized state. Thereafter, it can be seen that the cullet obtained by heating and melting at 1100 ° C. for 30 minutes does not produce any of gravel, color, devitrification, and deliquescent. In addition, no gravel, color, or bubbles were generated in the glass produced using the cullet. In addition, the cullet of Example 5 obtained by performing a deironing process after roasting the trona ore, mixing with silica sand, and heating and melting also had good properties as described above. Therefore, it can be seen that the cullet obtained by the production method of the present invention can be used as a cullet for a glass raw material without any practical problems.

On the other hand, the cullet obtained in Comparative Examples 1 and 2 in which the roasting temperature was as low as 400 ° C. and Comparative Examples 3 to 6 in which the roasting was not performed, the cullet itself was colored. Since coloring occurs in the glass produced by using the same, it is understood that the glass is not suitable as a cullet for a glass raw material.

[0068]

As described above, according to the present invention,
Mixing and roasting silica sand with trona ore prepared to a particle size of 10 mm or less, or mixing and mixing silica sand after roasting the above trona ore, heating and melting the trona ore and silica sand as a glass raw material A cullet that can be used without any practical problems can be manufactured. Therefore, it becomes possible to manufacture the glass material cullet with good productivity and at low cost.

[Brief description of the drawings]

FIG. 1 shows a mixture of trona ore and quartz sand mixed in a mixing ratio (Na ₂
4 is a chart showing the molten state, devitrification, and deliquescent when heating and melting are performed for 30 minutes while changing the heating temperature and O / SiO ₂ , respectively.

FIG. 2: A mixture of trona ore and quartz sand is mixed in a mixing ratio (Na ₂
4 is a chart showing the molten state, devitrification, and deliquescent when heating and melting at 1000 ° C. while changing the heating time and O / SiO ₂ ), respectively.

Claims (6)

[Claims] 1. A trona ore prepared to a particle size of 10 mm or less,
Mix silica sand, and in an oxygen-containing atmosphere at 500 to 900 ° C,
A method for producing a cullet for a glass raw material, comprising roasting for at least one minute and then heating and melting. 2. A trona ore prepared to a particle size of 10 mm or less,
A method for producing a cullet for a glass raw material, comprising roasting at 500 to 900 ° C. for 5 minutes or more in an oxygen-containing atmosphere, mixing silica sand, and heating and melting. 3. The glass raw material cullet according to claim 1, wherein a mixing ratio of the trona ore and the silica sand is 45/55 to 30/70 by weight as Na ₂ O / SiO _2. Manufacturing method. 4. The method according to claim 1, wherein the roasting is performed in a fluidized state for 5 to 30 minutes. 5. The method for producing a cullet for a glass raw material according to claim 1, wherein the roasting and the heat melting are continuously performed by a rotary kiln. 6. The method of claim 1, wherein before or after roasting of the trona ore, the iron ore is prepared to have a particle size of 5 mm or less and is subjected to a deironing treatment.
6. The method for producing a cullet for a glass raw material according to any one of items 5 to 5.