JPS5860637A - Raw material silica sand for glass - Google Patents

Abstract

PURPOSE:To increase the dissolution speed and the cleaning speed of silica sand and to enable the increase in the production of glass and the reduction in the dissolution energy, by attaching a sulfate and sulfite to the surfaces of the particles of the silica sand. CONSTITUTION:A silicate and/or a sulfite is attached to the surfaces of silica sand particles. Any application may be utilized, for example, silica sand is blended with the sulfate and/or the sulfite in the presence of a proper amount of water, silica sand is heated with a mixture of the sulfate and/or the sulfite at >= the melting point of the sulfate or the sulfite, etc. Sulfates or sulfites of alkali metal or alkaline earth metal are commonly used as the sulfate and the sulfite to be used as a clarifier for glass.

Description

[Detailed description of the invention] The present invention relates to soluble silica sand for glass raw materials.

Plate glass and container glass, which are commonly known as glass, are soda-lime-silica glasses, and their raw materials are often made of soda carbonate (soda ash), limestone, dolomite, and silica sand as the main components. A small amount of a clarifying agent such as mirabilite or sodium sulfite and, if necessary, a reducing agent such as carbon are used.

Usually, these ingredients are mixed together in a mixer,
It is prepared as a powdered batch containing several percent water, and this batch is put into a high-temperature glass melting furnace and melted by heat to finally produce homogeneous glass.

In this dissolution process, the least reactive substance among the above raw materials is silica sand, and therefore the dissolution rate of silica sand controls the vitrification rate of the batch.

Among the above raw materials, soda ash is used in large quantities as a flux that reacts with silica sand to promote vitrification of the silica sand.

On the other hand, small amounts of mirabilite, sodium sulfite, etc. are used as so-called fining agents, with the main purpose of removing bubbles generated in molten glass, but the effect of these substances on dissolving silica sand is also ignored. There are things I can't do.

In other words, taking Glauber's salt as an example, in the relatively low temperature range at the initial stage of batch melting, Glauber's salt remains in the liquid phase for four hours and collects at the interface between the glass melt and undissolved silica sand particles and bubbles. Since the liquid phase has a high degree of fluidity, it acts like a surfactant and promotes dissolution of undissolved silica sand particles and expulsion of bubbles.

Furthermore, in the high temperature range, mirabilite decomposes and bubbles are generated, which causes intense convection of the melt on the surface of the undissolved silica sand particles, causing mixing and homogenization, which promotes the dissolution of the undissolved silica sand particles. has.

As mentioned above, in the past, raw materials such as silica sand, soda ash, limestone, and dolomite, clarifiers such as Shoyuki's Glauber's Salt and sodium sulfite, and optionally a reducing agent such as carbon, were combined in the presence of t&% moisture. Since the batch is prepared by mixing simultaneously, the fining agents such as mirabilite and sodium sulfite will be uniformly dispersed in all the raw materials.

The purpose of the present invention is to provide silica sand for glass raw materials with excellent solubility that effectively exhibits the effects of mirabilite, sodium sulfite, etc. on the surface of particles. Silica sand for glass raw materials to which sulfate and/or sulfite is attached.

According to research by the inventor of the present application, considering the above-mentioned effects of mirabilite, sodium sulfite, etc., it is desirable that these substances exist on the surface of silica sand particles, which is the least reactive raw material among the raw materials. .

Silica sand and a clarifying agent such as sulfate and/or sulfite,
Soda ash9 Before mixing with other raw materials such as limestone and dolomite, the surface of the silica sand particles is treated to coat with sulfate and/or sulfite, and then mixed with the other raw materials mentioned above. The resulting glass batch has extremely superior solubility compared to glass batches prepared by conventional conventional methods, and both the dissolution rate and clarification rate of the silica sand are greatly increased. By using the same batch, it is possible to increase production and reduce melting energy.

In the present invention, it is important to attach sulfate and/or sulfite to the surface of the silica sand particles in order to promote subsequent dissolution, and any method may be used for the attachment.

That is, the attachment method includes a method of mixing silica sand and sulfate and/or sulfite in the presence of appropriate moisture;
A method of heating a mixture of silica sand and sulfate and/or sulfite to a temperature equal to or higher than the melting point of the sulfate or sulfite;
Alternatively, a method may be employed in which silica sand is moistened with a hydroxide solution or suspension, such as a caustic soda aqueous solution, and then brought into contact with 802 gas. The state of adhesion may be any state such as a film covering the entire surface of the silica sand particles, a state where the particles are locally adhered, or a state where the particles are fixed. Further, substances other than sulfate and/or sulfite, such as carbonate, nitrate, or hydroxide, may be mixed in as substances adhering to the surface of the silica sand particles.

In the present invention, sulfates and sulfites are usually sulfates or sulfites of alkali metals or alkaline earth metals used as glass refining agents, specifically, glauber's salt digypsum and barium sulfate.

Sodium sulfite, etc. can be used, and its additive content is as follows:
The amount to be added to the batch as a clarifying agent in ordinary glass melting may be sufficient.

In terms of specific numerical values, it is preferable to add sulfate and/or sulfite to 100 parts by weight of silica sand in an amount of O0j to 1ON parts, preferably O0g to q, 0 parts by weight.

Note that when silica sand is coated with sulfate and/or sulfite, a reducing agent such as carbon may be present together with sulfate and/or sulfite.

In this way, the reducing agent is reduced to one of the sulfates and/or sulfites.
By coexisting in a range of 0% or less, solubility is further improved.

Examples of the present invention are shown below.

Example / Each glass raw material having the proportion shown in Table 1 was prepared, and 700 parts of silica sand, 9 parts of mirabilite and 0.2 parts of carbon were mixed well by adding q parts of water. The remaining raw materials and 3 parts of water were added and further mixed so as to achieve the blending ratio shown in Table 1. This is used as an example sample.

A uniform film of mirabilite was formed on the surface of silica sand mixed with mirabilite and water.

Separately, as a comparative sample, a sample was prepared in which all the raw materials shown in Table 1 were mixed together with 9 parts of water.

Table 1 Silica sand Dolomite Limestone Soda Glauber Carbon 1
00 21 'j, 29 410.
+2 Put both of the above samples into a platinum crucible and heat in an electric furnace.
! ; It was melted at a temperature of 0°C for a predetermined time to form glass.

When the number of bubbles and undissolved silica sand particles contained in the produced glass 30fJ was measured, the results were as shown in FIGS. 1 and 2.

Under the same melting conditions, the Example sample was a glass with a bubble scattering of about 2/J and a number of undissolved silica sand of about 2/2 compared to the Comparative Example sample.

Example 2 700 parts of silica sand and 1 part of Glauber's salt were mixed well with the addition of 1 part of water. This mixture was heated at qoo''C for 10 minutes to coat the surface of the silica sand with Glauber's salt, and then the remaining raw materials shown in Table 1 and a water portion were added and mixed to prepare an example sample.

This example sample and a comparative example sample prepared in the same manner as Example 1 were heated in an electric furnace, /If! ; It was melted and vitrified at O''C.

The glass obtained by melting the Example sample had a foaming rate of about 2.5% compared to the glass obtained by melting the Comparative Example sample. The number of undissolved silica sand is approximately 2
It became 7j.

A comparative test similar to that in Example 1 was conducted using sodium sulfite in place of Glauber's salt in Example 1 and using the same blending ratio as in Example 1, and the same effects as in Example 1 were observed with sodium sulfite as well.

[Brief explanation of drawings]

Figures 1 and 2 are graphs showing the difference in dissolution rate between a batch using the silica sand for glass raw material according to the present invention and a conventional batch. Stupor time (minutes)

Claims (1)

[Claims] Silica sand for glass raw materials, characterized in that sulfate and/or sulfite is attached to the surface of silica sand particles.