NO761761L - - Google Patents

Abstract

Process for the manufacture of glass

Description

Previously known methods for the production of glass melt limit the glass compositions used for this purpose to contain only those ingredients which can withstand the environment in the respective glass melting apparatus. In the presently known methods for the production of molten glass with special properties or forming ability, it is necessary to introduce into the melting furnace all the components that must be present in the finished molten glass composition to achieve said properties. in many cases, the presence of certain of these components in the melting apparatus is not desirable due to volatility/ corrosive nature of the constituents concerned or harmful effects on the environment. The consequence of this is, as it has been known for years, that certain glass compositions cannot in practice be produced commercially:> because that they. contains components that are volatile, cause corrosion or have a harmful effect on the environment.

However, certain types of glass containing aggressive components have very undesirable properties and are therefore still produced commercially under such unfavorable conditions that the production/costs increase considerably. Glass compositions containing borosilicate usually include such volatile constituents as boron oxide (B^^), fluorine (F2) and sodium borate (Na^.XB^^). These components are not only volatile at the operating temperatures occurring in the melting apparatus, but they also cause a shortening of the lifetime of the melting apparatus by chemical attack on refractory material in the apparatus.

On this background, the present invention applies to an improved method for the production of fused glass compositions which are suitable for subsequent shaping into useful objects made of glass, the present application constituting an addition to Norwegian patent application no. 75.3958.

In the present method for producing glass, the components of the desired molten glass composition are selectively divided into two or more melting groups. These melt groups are produced separately, preferably as melt masses. One group, usually the one with the largest mass, is chosen as the base or main group, while the other groups are then incorporated into and homogenized in this base melt to achieve the desired glass melt composition.

The classification criteria' that apply to the composition of the melting groups can e.g. be based on the constituents' melting temperature or on any other appropriate material property, such as corrosion effect, softening point, volatility, etc. The classification properties for one group need not necessarily exclude all constituents in other groups. If e.g. the components are classified by melting temperature, the temperature range for one component group may overlap the temperature range for other component groups.

Thus, two or more groups of glass components can contain one and the same common component. It may also be found desirable in the formation of a certain melting group in certain cases and include a constituent that was otherwise excluded by the classification criteria applicable to the group, with the purpose of facilitating melting of the group in question or otherwise changing its properties with it purpose of achieving the best possible treatment properties for the melting group in question.

When applying the basic principles of the invention in the production of a molten, fiber-forming glass composition,

containing silicon dioxide (SiC^), aluminum oxide (Al^O^), calcium oxide (CaO), boron oxide (B^^)/fluorine (F2) and sodium oxide (Na2O), two separate melting groups can be determined. The most volatile constituents, namely ^O-j, F2 and Na2O.XB2Og, are preferably grouped together as a group of volatile oxides. Remaining constituents, namely SiO 2 , Al^<O>^, Na 2 O and CaO, can

together form a group of relatively low-volatile materials. This non-volatile group is known as soda glass, a glass composition which is relatively common within the glass industry and can be produced as a molten base glass in a glass melting furnace with high production capacity and of the continuous type, as is common within the glass industry. To this relatively low-volatile, molten base glass composition, the volatile component group can be added either as a molten composition or as a raw material composition. The volatile component group can be introduced into the molten base composition at any suitable location downstream of the low volatile component group's melting range. Preferably, the volatile component group is introduced into the molten base glass immediately downstream of the outlet of the melting apparatus used for melting down the base glass, whereby the base glass's output temperature and residual heat can be advantageously utilized. However, the volatile component group can also be introduced directly into the mouth area of the melting apparatus used for melting down the base glass, or at any other appropriate or otherwise advantageous location between the area where the base glass is melted and the location where the finished glass is formed .

As base composition, the melt group that represents the largest volume-wise part of the total material composition is usually chosen. thus, for most commercial types of glass, the ratio between base part and additive part will lie within the range from 1:1 to 20:1.

By carrying out the present method in several stages in the manufacture of glass, design freedom can be achieved with regard to the manufacture of the melting apparatus to a degree that has hitherto been completely unknown within the glass industry. The construction and function of a melting apparatus thus no longer need to be dictated by the composition of the glass melt to be produced in the apparatus. Aggressive glass compositions can be put together in two or more melting groups, so that the more difficult components, such as e.g. the highly volatile components can be taken out of the composition and repaired separately from the less troublesome components. In general, the volatile constituents most difficult to handle in modern glassmaking processes are boron oxide (6202), sodium borates

(Na20.xB202)/which is formed in the presence of Na20 and B203, as well as fluorine (F^) and lead oxide (PbO). These components generally make up a smaller part of the total glass composition and have relatively low melting temperatures. For this reason, they can be melted separately in a specially constructed melting apparatus, which is significantly smaller in size than the melting apparatus for the base glass and can work at a lower temperature than this. Thereby, there will be less evaporation loss, and as the melting apparatus for the volatile components is small compared to the commercial melting apparatus of the tank type, the problems of preventing pollution will be reduced to a significant extent.

Most volatile components in gas compositions are also solvents for known refractory materials. A reduction of the volatile constituents present in a glass melting apparatus,

to whatever extent this may occur, it can thus be expected to result in an extension of the smelter's lifetime. In the commercial melting of borosilicate glass containing at least 3%2'er ^St according to the invention, it was found that the lifetime of the melting apparatus can be extended by about 100% by reducing the current B2O2 in the melting apparatus by 50%.

According to the present invention, a desired glass composition can be produced by separating components with a high melting temperature and components with a low melting temperature in the composition in question into at least two different groups,

as well as by treating each of the groups separately, during which said components with a high melting temperature are brought to a melting state. With this material in a molten state, the materials with a low melting temperature can be added directly, after which the two groups of materials are soon, if not immediately, subjected to vigorous stirring or mixing of their constituents by the application of external forces to such an extent that the combined composition is homogenized. Insofar as said components with a low melting temperature can be affected to a significant extent, if the homogenized combination with a high melting temperature is not to be used immediately, the temperature of the homogenized composition is preferably lowered

to a value close to its new softening point, with the aim of reducing the tendency for volatile constituents to be emitted in gaseous form.

Another distinctive feature of the present invention is that the part of the material composition that has a high melting temperature, in the absence of the components in the part that has a low melting temperature, can be effectively preheated in the raw material state to a much higher temperature for the transformation to a molten mass to begin, than in in the event that the two parts of the material composition are combined in a common batch of material, such as in conventional glass production.

Energy consumption, development of evaporating gases and the size of the melting apparatus are all factors that can be reduced in accordance with the principle measures proposed in accordance with the present invention. Moreover, the service life of the refractory material that receives the bulk of the melt feed can be easily increased to a considerable extent. As the residence time for materials with a low melting temperature in areas with a high temperature is reduced to a considerable extent, materials with a low melting temperature and which are needed for the production of a glass composition are thereby consumed to a much lesser extent than is the case when producing glass by conventional melting methods . such materials with a low melting point include fluxes that are required to lower the melting temperature, as well as additives to improve the durability of the finished glass material. These components are usually considerably more expensive than the silicon-type base material in the composition. Consequently, the costs for the raw material used in the production of a type of glass with the desired composition can also be significantly reduced.

A distinctive feature of the present invention applies in particular to an improved method for the production of molten glass and glass products, especially, but not necessarily, glass fibers, as well as more specifically a method for eliminating, regulating or simplifying measures to prevent the entry of volatile components into the atmosphere from the components in the material composition that contain volatile components, especially in the case of material compositions that contain at least 3% boron oxide with or without components that contain fluorine. Glass compositions that are suitable for the production of glass fiber for glass wool, plastic reinforcement or other end products are made, e.g. usually of borosilicate glass,

and such glass compositions contain volatile constituents in amounts sufficient to adversely affect the forming properties, such as boron oxide (B^^), fluorine (F2) and/or sodium borate (Na2OxB2C>2). These components are not only volatile at the smelter's operating temperatures, but also reduce the lifetime of the apparatus through corrosive or chemical attack on the apparatus's refractory material due to their presence in the melt.

When the volatile constituents have been removed from borosilicate glass and other special glasses used for the production of glass fibers, it has been found that the remaining glass constituents can in practice be melted in a furnace of a conventional type, either by the remaining constituents forming what can be considered a eutectic namely at the compositions that have the lowest melting temperature; or in that the remaining components can at least be sufficiently melted in a conventional furnace. In certain cases, however, the forming properties of the remaining components are in both cases insufficient for handling and forming the glass into the desired end product, primarily due to

that the temperatures at which the glass is viscous and/or liquid are far too high and inappropriate for forming in a practically feasible manner. According to the present invention, the volatile components are then melted separately and then added to the molten mass of the remaining components and intimately mixed with this, preferably by mechanical stirring, for homogenization of the composite material mass and production of suitable forming properties, after which the end products are shaped. It is known in the industry that the efficiency of the glass manufacturing process can be improved by preheating the composite batch of raw materials before it is introduced into the melting apparatus. However, the increase in efficiency has been found to be limited by the particular sintering temperature of the composite batch. When carrying out the present method for glass production in several stages, the sintering temperature of the composite raw material batch for the base glass, which represents the largest part

of the total amount of material, is increased to a significant extent by selective omission of the material components that are sintered at a relatively low temperature, such as e.g. soda ash. The components with said lower sintering temperature can be treated separately as a group with or without preheating in the manner that is considered most effective for the particular components included in the group. Thus, for a given desired glass composition, a melting process can be specified and a melting apparatus constructed to achieve the greatest possible thermal efficiency. In the present method for producing glass in several stages, it is thus no longer necessary to melt all components of the desired glass composition in a common glass melting apparatus, in the form of a single batch of raw material containing all said components. However, for a given desired glass composition, a melting process can now be specified and a melting apparatus designed to achieve the most appropriate manufacturing process with regard to harmful impact on the environment, energy recovery, the lifetime of the melting apparatus or a combination of these factors, all depending on the purpose sought achieved.

The invention will now be explained in more detail with reference to the attached drawings, on which: Fig. 1 is a phase diagram for the Si0^ii;eNa20 - CåO system, and in which isotherms are shown for the Na203Ca06si02 range; Fig. 2 is a phase diagram for the SiO2 - A^O^ - CaO system, and shows the composition at the eutectic point and corresponding isotherms; Fig. 3 is a flow diagram for use during the subsequent description of export example VI; Fig. 4 is a diagram showing representative curves illustrating the viscosity differences between the molten material compositions in Example II; Fig. 5 is a vertical projection schematically showing elements of a glass melting apparatus with two zones, and which is suitable for reproduction

of the present invention, and

Fig. 6 is a vertical projection which schematically shows elements in a melting apparatus which is suitable for carrying out the present invention.

The present invention is particularly applicable for the production of borosilicate glass, which is usually used for the production of glass fibres. As will be shown below, however, the present invention provides advantages in all areas of the glass framing industry. Although the following description of embodiment examples for the method of the invention will particularly apply to the glass fiber industry, it will be understood that the basic principles of the method of the invention also

can be applied in other glass-melting operations.

According to Fay V. Tooley: The Handbook of Glass Manufacture, 1974, a glass composition can contain almost any of the elements in the periodic table. However, few glass compositions lack significant amounts of silicon,

boron or phosphorus. In most cases, these elements occur in oxide form. Within the glass manufacturing industry, these and other glass-forming oxides are referred to as "glass formers", while the oxides that have glass-forming properties to a small extent are called "modifiers", while a group of materials between the aforementioned material types are called "intermediates". The above-mentioned author Tooley gives on page 3 of the above-mentioned handbook the following classification of glass formers, intermediates and modifiers:

The glass formation potential for the oxides in the above table decreases from top to bottom in each column and from left to right in the table. Of the specified materials, B2°3 thus exhibits the worst glass-forming properties and K20 the worst such properties. However, there is no sharp dividing line between As2O3 and Al2O3, nor between ZnO and MgO.

Tooley calculates on page 5 of his handbook the approximate composition of the commercial glass compositions indicated in the following table II. It will appear from this table: II that the borosilicate and lead glass compositions contain two very good glass formers, namely B203 and SiO2, together with Al2°3 which can act as a glass former even though it is classified as an inter-medium in table I. These glass types thus provide particularly good conditions for the production of glass by the present method. Each of the aforementioned types of glass can be composed of two separate material compositions or melting groups. One of these groups can e.g. contain SiO2 as a glass former and the other may comprise B2<D3 for this purpose. Alternatively, advantage can be taken of the glass-forming properties of the intermediate A^"2°3/sale<^es that three separate material groups are formed, under which the third group comprises Al203 as glass-forming oxide. Each of these melting groups can in turn be composed to achieve certain handling advantages, depending on the particular difficulties faced by the glass manufacturer in question.

The compositions for container glass indicated in Table II

lean is also produced in accordance with the stated principles for the method of the invention by taking advantage again of the glass-forming properties of A^O^, which is used as a glass-forming oxide in one of the assembly groups. A more practical option for the production of these types of glass in accordance with the method of the invention can, however, involve the composition of a common base composition of SiO2, Na2O and CaO as well as an additive group containing the remaining components as well as a further part of SiO2, which thereby serves as a glass former in this material group. The precise material composition and the exact mixing ratio can constitute a compromise between the desired melting properties for the two aforementioned types of glass. If it is desirable to reduce the melter's operating temperature, it can e.g. be expedient and form a base composition that lies within the Na203Ca06Si02~ area in the phase diagram for Si02-Na20©g CaO in fig. 1, so that the melting apparatus can be operated at a temperature between 800 and 1050° C to achieve the lowest possible operating temperature. The additive composition and mixing ratio can be determined in accordance with this. As a general explanation of how glass is produced according to the method of the invention has now been given, in the following certain special embodiment examples will be described and the advantages thereby obtained indicated.

EXAMPLE I

BOROSILICATE GLASS FOR INSULATION WOOL

U.S. Patent Nos. 2,877,124 and 2,882,173 describe glass compositions suitable for the manufacture of glass wool products. It is particularly advantageous to produce these compositions

by a melting process according to the present invention, as will be apparent from the explanation below. In general, fibre-forming glass compositions for glass wool have the following material composition, stated in parts by weight:

The most important volatile component in the above-mentioned glass melt is sodium borate, which is formed by reaction between Na20 and & 2°3' which ^e99e occurs in the present glass melt. In consideration of the aforementioned occurrence of sodium borate, the material composition of the melt can be written as follows:

According to the basic principles of the invention, the above-mentioned components can be grouped in accordance with their relative volatility into two melting groups which are indicated below.

Group I (non-volatile constituents)

Group II (volatile constituents)

The material composition in group I can be recognized as soda-quartz glass, which is very close to the material composition for window glass, and this type of glass can indeed be made to form fibres, but is unsuitable as insulating glass wool due to absence of<B>2°3*Such presence of & 203 is necessary to achieve satisfactory resistance to heat transfer as well as the necessary chemical properties on the fiber surfaces to achieve bonding to phenol formaldehyde which is used as a binder. However, soda quartz glass is less aggressive during the manufacturing process than the desired glass wool composition for borosilicate glass stated above. However, the material composition in group II is particularly volatile and corrosive. For this reason, the components of Group I are compounded as a base glass melt in a continuously operating glass melting unit of the type common in the glass manufacturing industry. The sodium borate components in group II are then introduced into the base glass melt which is composed of the stated components in group I, either in molten form or as a raw material composition. As the materials in group II make up approximately 11% by weight of the total amount of material/they can be melted in a significantly smaller melting unit and at a considerably lower operating temperature than the base composition. Thus, less loss of sodium borate by evaporation can be expected/which simplifies the task of monitoring contaminants. As the soda-quartz glass in group I is approximately half as corrosive as the specified borosilicate glass composition for the production of glass wool, an increase of around 100% can also be expected when it comes to the lifetime of the refractory lining of the melting apparatus. ;EXAMPLE II;BOROSILICATE GLASS FOR TEXTILE FIBERS;U.S. Patent No. 2,334,961 describes a material composition for borosilicate glass of the type commonly called E-glass and which can be easily formed into textile fibers for use mainly as reinforcement in plastic materials/car tires and the like. In general, such E-glass has the following composition calculated in weight proportions: ; The volatile components that cause problems in this glass melt are B2°3'F2°9^2°'In the same way as the example of glass wool glass given above, two melting groups can therefore be arranged divided as follows: ;Group I (not -volatile constituents); Group II (volatile constituents); In the grouping set out above, the highly volatile components in group II, which make up about 8 percent by weight of the desired fiber-forming molten glass composition, can be assembled separately in a relatively small melting apparatus and then added to the molten base glass composition, thereby achieving similar advantages as by the previously mentioned production of glass composition for glass wool.; EXAMPLE III; TEXTILE FIBER GLASS ON A EUTECTIC BASIS; The present invention brings further advantages when it comes to the production of E-glass compositions of the kind mentioned in the above-mentioned example II. in this connection, reference must be made to the indicated phase diagram in Fig. 2 for the CaO / Al203 / Si02 system. ;If the material composition for the non-volatile group is changed to: ; eutectic material composition is achieved, thus the main melting apparatus, which is used for melting down the non-volatile material composition according to group I, can be operated at the lowest possible operating temperature. ;The remaining components are assigned to group II, namely the group of the volatile components, which are thus composed in the following way: ; A further advantage achieved in this way is that the last-mentioned material composition allows the use of less expensive raw materials, such as e.g. colemanite as a partial source of ^O^, whereby the need for the more expensive boric acid is reduced. ;EXAMPLE IV;SODA GLASS;A common glass composition that can be used in the manufacture of window glass or bottle glass is the following: ; These glass compositions contain a significant proportion of ^2*3, which has a high corrosive effect on the refractory lining of the melting apparatus. It should thus be advantageous to reduce the amount of Na2O present, taking into account the melting apparatus

lifetime and economic operation.

In accordance with the basic principles of the present invention, two possible fusion groups can then be composed in the following way:

Group I (melt with low corrosive effect)

Group II (melt with high corrosive effect)

The specified melt with low corrosive effect according to group I is the larger of the two melts and can therefore be assembled as a basic part in a large continuously working melting apparatus of the kind that is usually used in the production of molten glass. The expected operating life of the melting apparatus that produces the basic part of the glass composition can thereby be extended due to the^substantial reduction of the material composition's corrosive effect.

The alloy according to group II, which has a high corrosive effect, can be assembled in a relatively small melting apparatus and supplied to the base part as a melt or sintering. Alternatively, the material composition according to group II can be introduced into the molten base glass as a composite raw material mixture, whereby the need for an additional melting apparatus is eliminated.

EXAMPLE V

EUTECTIC SODA GLASS

The flow temperature for the base glass in group I in example IV is estimated to be 1705° C, while that for the additive glass in group II is assumed to be 870° c. By changing the material composition in group I to the best eutectic composition, which is given by :

the composition's flow temperature can be effectively lowered to approximately 1305°C, so that an improved thermal efficiency is achieved in the melting process.

The additive part of the glass in group II must then be composed in the following way:

EXAMPLE VI

GLASS FOR MORE PRODUCTS

Fig. 3 shows a flow diagram for a plant for the production of a glass product, which can form the basis for the production of glass wool, a textile glass product, an E-glass product and a chemically resistant "C" glass product from one and the same glass composition. In this regard, the main glass group can have the following composition:

Since the main group of material components is free of volatiles

and corrosive components, a relatively long service life can be expected for the smelter, while the problem of evaporation loss and associated pollution is eliminated.

The above-mentioned main group of material components is alternatively mixed with the following additive groups:

In this way, the following glass products can be obtained:

Because of. the mixing ratio between additive part and main part, it may be physically advantageous to introduce the main glass group in additives no. 1 and no. 4, with subsequent homogenization of the mixture. Additive no. 2, however, also in this case causes problems in connection with evaporation of & 2°3' It is therefore suggested for experts in the field to prepare this additive by applying the principles of the invention to the present additive no. 1, so that the final material composition is achieved by repeating the method of the invention in several steps. The glass wool product can thus be produced by combining three mutually separate material compositions, which have been prepared in advance.

Almost every material composition for glass production can be divided into a base part and one or more additive parts, which by mixing and homogenization give a predetermined glass product with the desired material composition. In any case, the present particular composition of base part and additive part is largely a function of the purpose of the material handling, the physical properties of each material component and the available raw materials. Many deviations from what is usual may be necessary to achieve the desired end, whatever this may be.

Many of the problems which the glass manufacturing industry has faced up to now can be solved or reduced in importance by carrying out the invention's method for manufacturing glass in several stages. In U.S. Patent No. 2,900,264, a method is described for changing the material composition during glass melting in a continuously operating tank-type furnace, from normal composition to material composition for glow-resistant glass or vice versa, without expensive interruption of operation and cleaning of the tank. Changing from normal to glow-resistant glass requires, according to this patent document, a lowering of the Fe203 content in the tank by 0.355%. A transition period of 72 hours is required to achieve this change, and this creates a large amount of waste glass. According to the present invention, a base composition can be created from which normal, glow-resistant or very glow-resistant glass can be produced by incorporating an appropriate additive for each case into the base composition.

IN

With this method, a long adjustment period or interruption of operation for the tank is thus no longer necessary, and the amount of waste glass is reduced considerably.

In U.S. Patent No. 2,934,444, a method is further described by which loss of ^ 2°3 vec^ evaporation from a glass melting tank should be able to be reduced. In this method, however, borax and boric acid must first be synthesized to produce a sodium polyborate, which can later be used as a mixing ingredient. However, such pre-treatment of raw material increases the costs of glass production and reduces the overall thermal efficiency. However, this problem can be solved more efficiently and economically by utilizing the basic principles of the invention, as will be seen from example I.

According to U.S. Patent No. 2,411,031, account is taken of the variations in the material composition of optical glass that result from evaporation of certain constituents. However, the stated principles according to the present invention can also be used, as discussed above, to solve the present problem with evaporation loss.

According to U.S. Patent No. 3,607,190, the intention is to save energy by preheating the batch of material before it is introduced into the melting apparatus. It is carefully ensured that the granules in the batch are not preheated to a temperature at which they melt or sinter together, as in this case they become sticky and difficult to transport. The temperature to which the material batch can be preheated is thus limited by the lowest sintering temperature for the components in the combined material batch. When using the method of the invention, however, the relevant components with a low sintering temperature can be removed from the base batch, whereby the preheating temperature of the batch can be increased. In this way, greater thermal efficiency can be achieved.

As the removed volatile material components are usually those which have the greatest corrosive effect on the refractory lining of the melting furnace, and the volatile exhaust gases attack the upper part of the tank, removal of these components will mean further savings in that the smelter

the lifetime of the device is extended.

When carrying out the present method for glass production in several stages, it will mostly be necessary to mix and homogenize melt compositions with significantly different properties with regard to viscosity, density, softening point, working point, yield point, surface tension, coefficient of expansion, modulus of elasticity and electrical resistance, on such way that a workable glass composition with different properties than each of the mixed material components is obtained. For this reason, the manner in which the melt components are mixed and worked together becomes of significant importance for the production of the desired final glass composition.

Fig. 4 shows visible curves indicating the relationship between viscosity and temperature for the material compositions in group I and group II in example II, as well as the material composition for the finally manufactured homogenized glass product according to this embodiment example. Additional curves, respectively representing fused quartz glass and 96% quartz glass are also plotted in this figure to provide the qualitative relationship between the curves.

The viscosity in the base composition according to group I at 1361° C log 2., 50, while that in the additive components according to group II at 1094° C has the value log 0.50. The final homogenized glass composition has a viscosity of log 2.50 at 1281° C. Thus mixing the additive according to group II into the base material composition according to group I can be compared to mixing ethylene glycol into corn syrup at room temperature.

In the main application, an apparatus is shown and described which has proven to be suitable for the production of textile fibers in accordance with the method of the invention. It has been found particularly desirable to provide mechanical mixing of the molten material compositions immediately after they have been combined. This has been found to be necessary to prevent the material components separating from each other in layers, mixing of the components becomes almost impossible if such layer formation is allowed.

Fig. 5 shows in vertical projection a cross-section through a melting furnace with two separate zones and which is suitable for the development of the present invention. The main melting chamber 60 can be arranged for heating by means of electric current flow or by burning fossil fuel, as desired, for melting down the constituents of the base composition. These components - in the molten base part are caused to flow through a submerged opening 61 and up through a riser 62 as well as into the suction field from a downwardly directed, pumpless stirring device 63. The additive part, which is composed for the transformation of the molten components, which are produced in zone 60 to the final material composition for the desired end product, is preferably introduced upstream of the agitator 63 through a suitable supply device 64. It may be desired to forcibly mix the molten base composition as it moves upward through the riser 62, by placing an upward pumping agitator in this area. Thereby, the residence time for the molten base composition in the zone 60 can be reduced.

The downward pumping agitator 63 initially ensures the mixing of the base part of the melt and the additive part. so that the obtained mixture can be emitted to a refining zone 65. Depending on the volatility of the mixed components in the zone 65, it may be appropriate to arrange a hood and associated outlet channel for the removal of any volatile exhaust gases to a cleaning device or a similar device, which, however, is not shown in the drawing.

From the refining zone 65, the resulting mixture passes to an upwardly directed pumping agitator 71 through an agitator inlet port 70, whereby the mixture is finally homogenized and made to flow into a prehardener 72 as a processable glass melt with desired properties for the manufacture of the intended products .

Many alternatives to the device in fig. 5 is possible for improvement

of its functional properties. Heating electrodes can e.g. be placed in the riser 62 to maintain the outlet temperature of the base part when it leaves the melting chamber 60, or to increase this temperature so that mixing of said additive into the base

the part is relieved. A mechanical or thermal mixing device can also be arranged in the refining zone 65 to increase the homogenization rate and to reduce the residence time in

this zone. Depending on the material composition being handled

and its relative properties, such as e.g. its viscosity or density, it may in certain cases be advantageous to

e.g. introduce flux components in the opening area 61 to lower the viscosity of the base composition for a further additive to be supplied. In this way, the base composition can be suitably prepared to receive further additives through the supply channel 64.

Fig. 6 shows an apparatus for carrying out the method of the invention and which is particularly advantageous in the event that three melting groups, one of which may be in raw material form, are to be mixed and homogenized into a material composition which can be formed into a desired end product. A molten base composition 80 is created in a melting apparatus, not shown, and is made to flow into a preheater 81. In this preheater 81 is placed a mixing block 82, which extends like a dam above the preheater, in the same way as block 13 in the main application. From the upper side 83 of the block 82, a cylindrical channel 84 extends in connection with an outlet 85, in the same way as for the block 13 according to the main application. Inside the channel 84 is placed a stirrer 86, which appropriately works for mixing, homogenization and forced pumping of the molten components downwards through the channel 84 and out through the outlet 85 to the downstream part of the pre-heater. A first additive is assembled as a molten material composition 90 in a melting apparatus 91 and is made to flow to an outlet opening 92. A second additive is assembled as a molten material composition 95 in another melting apparatus, not shown, and is made to flow through a nozzle 96, which extends through the melt portion 90 and into the outlet opening 92 for discharging a flow 97 of the melt 95 in the middle of a flow 98 of the melt composition 90, which thus encloses the melt 95 so that a combined flow 100 is formed. This composite flow 100, which is made up of both the first additive and the second additive, flows into said flow sequence of molten base composition upstream of the stirrer 86 and is sucked into this stirrer together with the base melt. The stirrer 85 ensures the mixing and homogenization of the three molten components to the desired final material composition. The apparatus in fig. 6 can be particularly advantageous in the event that the melt composition 95 is particularly volatile, as this melt component is completely surrounded by the melt flow 98, so that it is prevented that volatile components are emitted from the flow 97.

The molten material composition 95 can be assembled in a melting apparatus of the type shown in U.S. Patent No. 3,429,972, which is well suited for the production of molten material compositions of mineral constituents with a relatively high melting point, such as e.g. SiO2 The molten material composition 95 may be replaced by an unmelted raw material composition, as described in U.S. Patent No. 2,371,213.

The apparatus shown in fig. 6, can be appropriately • modified for handling a product glass composed of two melting groups. The melting devices 91 and 96 can thus be used for the assembly of a base melt and an additive, respectively.

The composite flow 100 can then be fed to a suitable mixing device of known design, and for this purpose can e.g. one or other of the devices described in the following U.S. patents is used: 3,942,968, 3,811,861, 3,725,025, 3,486,874, 3,174,729,

3,057,175, 2,730,338, 2,716,023, 2,688,469, 2,577,920,

2,570,079, 2,569,459 and 2,520,577.

By carrying out the invention's method for the production of molten material compositions for the production of glass, a new freedom has been achieved with regard to practically possible glass compositions. It is thus not only possible to put together special base glass varieties to improve the overall operating economy of glass manufacturing processes, but very volatile components, such as water, can now also be added to the molten glass composition.

Although the described embodiment examples constitute practical instructions for carrying out the invention, the invention's progress—

method is in no way limited to the details shown and described, as considerable modifications can be made within the scope of the invention.

Claims (37)

1. Procedure as stated in the main application, Norwegian patent application no. 75.3958 for the production of glass fibers from glass melt with the following composition: characterized by the following measures: a) a molten first assembly of: b) a different composition is produced from: c) said second composition is mixed into the first, molten composition, thereby producing a homogenization of the combined components into a glass melt of the desired composition for fiber formation, and d) said glass melt is formed into fibres. 2. Procedure as stated in claim 1, characterized in that the second material composition is produced as a molten composition. 3. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of glass fibers from a glass melt with the following composition: characterized by the following measures: a) a molten base composition is prepared from: b) an additive composition is produced from: c) said additive composition is mixed into the base composition, thereby producing a homogenization of the combined components to form said glass melt, and d) said glass melt is formed into glass fibres. 4. Method as stated in claim 3, characterized in that the additive composition is produced as a molten composition. 5. Method for producing glass fibers from a fiber-forming glass melt with the following composition: according to the main application, Norwegian patent application no. 75.3958, characterized by the following measures: a) in a melting apparatus with a tank for continuous flow, a molten base composition is produced from: b) the molten base composition is caused to flow from the melter into a preharden channel, c) while the molten base composition flows through the preharden channel, an addition of the following composition is added: d) said additive is completely homogenized into the molten base composition to form the intended fiber-forming glass melt. 6. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of glass fibers with the following material composition: characterized by ,. ■ the following measures: a) a molten, first material composition is produced with the following components: b) a different material composition is produced from the following components: c) said second material composition is mixed into the melted first material composition, thereby producing a homogenization of the combined components into a glass melt which can be formed into fibers with the desired composition, and d) said glass melt is formed into fibres. 7. Procedure as specified in claim 6, characterized by the fact that the other material composition is put together as a molten composition. 8. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of glass fibers from a glass melt with the following composition: characterized by the following measures: a) a molten base composition of the following components is assembled: as well as an additive composition of the following components: b) said additive composition is mixed into the molten base composition, whereby homogenization of the combined components of said glass melt is produced, and c) said glass melt is formed into glass fibres. 9. Method as stated in claim 8, characterized in that the additive composition is assembled as a molten composition. 10. Method as specified in claim 8, characterized in that said base composition comprises: and the additive composition includes: 11. Procedure as stated in the main patent application, Norwegian patent application no. 75.3958, for the production of glass fibers from a fiber-forming glass melt with the following composition: characterized in that the production of the fiber-forming glass melt includes the following measures: a) in a melting apparatus with a tank for continuous flow, a molten base composition of the following components is prepared: b) the molten base composition is caused to flow from the melter into a preharden channel, c) while the molten base composition flows through the preharden channel, an additive composition with the following components is added: d) said additive composition is completely homogenized into the molten base composition to form said fibre-forming glass melt. 12. Method as stated in claim 8, characterized in that the melted ice assembly has the following composition: and the additive composition consists of the following components: 13. Method as stated in claim 11, characterized in that the molten base composition consists of the following components: and the additive composition is composed of the following components: 14. Procedure as stated in the main patent application, Norwegian patent application no. 75.3958, for the production of glass products in which & 2°3 is a necessary component of the product's material composition; characterized in that a molten material composition is prepared which contains a first part of the desired product components, but is free of B2 °3', after which the remaining part of the desired components of the product is assembled separately and comprises E^O^ , and said remaining part of the constituents of said product are added to the first-mentioned molten material composition, the remaining part being carefully mixed and homogenized with the first-mentioned part to produce a glass melt with the desired material composition for the product. 15. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for melting borosilicate glass, characterized by the following measures: a) the components of the glass are divided into a boron oxide-free base part and an additive part containing the desired amount of boron oxide, b) the base part is melted to produce a molten mass, c) the additive part is introduced into the molten mass, and d) the additive part is mixed and homogenized with the molten mass in such a proportion that a borosilicate glass with the desired material composition is obtained. 16. Method as stated in claim 14, characterized in that the additive part containing the desired amount of boron oxide is prepared separately as a melt and introduced into the molten base part in a molten state. 17. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the manufacture of products from borosilicate glass, characterized by the following measures: a) a first molten material composition is prepared containing the components of said glass type which have a melting temperature higher than the evaporation temperature for ^O^, b) another molten material composition is prepared from the remaining components, and c) first and second molten material composition are combined and homogenized in such proportions that borosilicate glass with the desired material composition is obtained. 18. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of a borosilicate glass, characterized by the following measures: a) a basic part of the material composition of said glass is melted, this basic part being free of at least the majority of the boron oxide-forming ingredients, b) the rest of the material composition of the glass is supplied as an additive part, which includes boron oxide-forming ingredients, and c) the additive part is mixed and homogenized with the molten base part in such proportions that borosilicate glass of the desired material composition is obtained. 19. Method as stated in claim 17, characterized in that the additive part containing boron oxide-forming ingredients is prepared separately as a melt and is introduced into the molten base part in the molten phase. 20. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the manufacture of products of borosilicate glass, under which boron is included as a component in the raw materials in the form of & 2Q3' characterized by the following measures: a) a material composition containing the constituents of said glass is melted which has a higher melting temperature than the temperature at which an undesirable quantity & 2°3 v^ for<3ampe, b) another molten material composition is prepared from the remaining constituents, including I^O^, c) said first and second molten material composition are combined and homogenized in such mutual proportions that a borosilicate glass with the desired material composition is formed, and d) said borosilicate glass is formed into a commercial product. 21. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of glass with the desired material composition and content of at least three percent by weight B2 O3/ in such a way that a significantly reduced evaporation of ^ 2°3 is achieved, characterized by the following measures: a) a molten base composition is prepared which is essentially free of B2 03 , b) this base composition is melted in a melting apparatus and caused to flow through an outlet zone, while in a separate chamber an additive composition containing sufficient B2°3 is melted to significantly change the forming properties of the base composition, with the aim of obtaining an overall material composition that can be formed into a finished product of the desired material composition, c) the additive composition is added to the molten base composition, and d) the additive composition is completely homogenized into the molten base composition for the production of said glass of predetermined material composition. 22. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of borosilicate glass and the elimination, regulation or simplified regulation of exhaust gas to the atmosphere from the components of the raw materials that contain volatile substances, under which the borosilicate glass has at least a boron oxide content of 3%, characterized by the following measures: a) a molten base glass composition is prepared containing a major part of silicon dioxide and a modifier in the absence of the material group which contains the major part of the volatile materials and comprises ^ 2°3°9 F2' b) the molten base composition is caused to flow from a melting region into a preharden channel; c) in a separate chamber, a material composition is melted which includes said constituents with volatile substances in the material group, B2 °3 and Fj; in sufficient quantities that, when added to the base composition, they will significantly change the forming properties of the total material composition and form a borosilicate melt with a content of at least 3% B2 °3' as well as d) the additive composition is completely homogenized into the molten base composition to produce a glass with the desired forming properties. 23. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of borosilicate glass fibers from raw materials" with volatile substances, within the group of constituents with volatile substances that include B2 °3/ fluorine and sodium borate, vessels equipped with the following measures: a) a molten base composition is prepared which is essentially free of constituents containing volatile substances, b) in a separate chamber, a molten additive composition is prepared which includes the constituents comprising volatile substances, and c) the molten additive composition is combined with the molten base composition for subsequent homogenization and production of the desired fiber-forming glass type. 24. Method as stated in claim 22, characterized in that: a) the additive composition is a glass that is melted by causing electrical energy to pass between electrodes immersed in the additive glass, b) the raw materials for the additive glass are introduced into a bed of such materials on said melt of the additive glass, for regulation of the evaporation of the constituents containing volatile substances, and return of the bulk part of these to the smelting of additive glass. 25. Method as stated in claim 23, characterized in that the base composition is melted by combustion gases being fed over the surface of the melted base composition and the raw materials for this composition being fed into this melt. 26. Method as stated in claim 24, characterized in that the molten additive glass is combined with the molten base glass by mechanical stirring. 27. Procedure as stated in claim 24, characterized in that the base composition includes: while the additive composition includes: 28. Method as stated in claim 24, characterized in that the base composition includes: while the additive composition includes: 29. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for "production of a glass product, characterized by the following measures: a) as a first material composition, part of the glass's components are fused to produce a molten, amorphous mass, which lacks one or more of certain properties that are necessary for the production of the desired glass product, e.g. appropriate viscosity, pour point, softening point, melting point or surface tension; b) one or more additional molten material compositions are prepared, which contain constituents which are collectively complimentary to the aforementioned material composition with respect to the formation of said glass product, but each of the additional material compositions lacks one or more of certain properties necessary for manufacture of the desired glass product, such as adequate viscosity, flow temperature, softening point, melting point or surface tension; c) the further molten material compositions are mixed with the first-mentioned composition in such proportions that a glass melt with properties suitable for forming the desired glass product is formed, and d) said glass melt is formed into a commercial product. 30. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of glass with the desired material composition, kar a&k terized by the following measures: a) a composition of raw materials is heated to a melting state which includes components with a high melting temperature in the desired material composition, b) the remaining part of the desired material composition and which is necessary for the production of said glass, is introduced at a significant depth below the surface of the molten material, and c) the combination of constituents is stirred vigorously so that substantial evaporation of constituents from the molten material takes place, in order to obtain a homogenized glass melt of the desired material composition. 31. Method as stated in claim 30, characterized in that the remaining part of the desired material composition is introduced into the molten material in particle form. 32. Procedure as stated in claim 30, vessels characterized in that the remaining part of the desired material composition is introduced into the molten material in molten form. 33. Method as stated in claim 30, characterized in that the glass melt, after careful stirring of said components, is lowered to a temperature that is closer to the softening temperature of the glass in order to achieve an increase in the viscosity of the glass, thereby tending to evaporate components with a lower melting temperature in said remaining part is reduced. 34. Method as stated in claim 30, characterized in that the raw material charge is in the form of pellets and is first heated in this form to a temperature value just below the melting temperature without said pellets agglomerating, after which the heated raw material is exposed to heat supply for transition to molten state. 35. Method as stated in claim 30, characterized in that said remaining part comprises a significant part of the constituents of the glass's material composition which constitute the solvent for refractory material. 36. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of a glass product with the desired material composition, characterized by the following measures: a) preparation of a molten material composition comprising the components of said material composition which have a melting point at a higher temperature, b) the remaining part of the desired material composition and which includes a significant part of the material composition's constituents with a lower melting temperature, is introduced into the molten material, c) in the aforementioned remaining part is introduced at a level below the above- .the surface of the molten material, so that the emission of components with lower melting temperatures from the melting surface is substantially reduced, and d) coercive and careful - processing of said parts of the material composition to a homogenized state for the production of said glass of the desired composition/ after which the glass is brought to an appropriate temperature for shaping into the desired glass product. 37. Procedure as stated in the main application, Norwegian patent application no. 75.3958, for the production of a glass product of the desired material composition, characterized by the following measures: a) melting of a portion of said material composition which comprises a significant part of the composition's constituents and which has a higher melting temperature than the desired material composition, b) another part of said material composition and with a considerably lower melting temperature than the desired composition is introduced at a level below the surface of the melted part, said second part comprising the remaining components required for the production of said glass product with the desired material composition, and c) the joined parts are processed quickly and vigorously into a homogenized glass melt with the desired material composition.