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MX2008005088A - Pellets for se encapsulation - Google Patents

Pellets for se encapsulation

Info

Publication number
MX2008005088A
MX2008005088A MXMX/A/2008/005088A MX2008005088A MX2008005088A MX 2008005088 A MX2008005088 A MX 2008005088A MX 2008005088 A MX2008005088 A MX 2008005088A MX 2008005088 A MX2008005088 A MX 2008005088A
Authority
MX
Mexico
Prior art keywords
selenium
glass
pellet
pellets
compound
Prior art date
Application number
MXMX/A/2008/005088A
Other languages
Spanish (es)
Inventor
Collart Olivier
Cherdon Benoit
Carleer Pierre
Original Assignee
Carleer Pierre
Cherdon Benoit
Collart Olivier
Glaverbel
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Carleer Pierre, Cherdon Benoit, Collart Olivier, Glaverbel filed Critical Carleer Pierre
Publication of MX2008005088A publication Critical patent/MX2008005088A/en

Links

Abstract

Pellets for Se encapsulation Pellets encapsulating selenium or a compound of selenium comprise one hollow cavity filled with the selenium surrounded by a matrix which is able to form an eutectic with at least one of the constituents of a batch of molten raw materials for the manufacture of glass.

Description

PELLETES FOR SELENIO ENCAPSULATION BACKGROUND OF THE INVENTION The present invention relates to pellet materials comprising selenium. More precisely, it refers to pellets that encapsulate selenium and / or at least one selenium compound. In particular, the invention relates to pellets that encapsulate selenium that can be incorporated into a batch mixture of components suitable for glass melting manufacturing processes.
SUMMARY OF THE INVENTION According to a first aspect, the invention provides pellets that encapsulate selenium and / or at least one selenium compound as defined in Claim 1. In accordance with a second aspect, the invention provides a process for manufacturing of pellets according to claim 7. According to a third aspect, the pellets according to claim 1 are used as a raw material of selenium to incorporate a molten glass lot according to claim 11. In accordance with a fourth aspect, the invention provides a method to reduce the burning of selenium in a process for making glass comprising selenium in accordance with claim 12. According to a fifth aspect, the invention provides a bicarbonate lime glass comprising selenium according to claim 13. Dependent claims define additional preferred embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION The present invention can provide one or more of the following advantages: • Simple mechanical method of pellet preparation: Simplicity of Selenium incorporation, similar to any other traditional glass component; • No requirements for any special dispensing equipment or dispenser and / or particularly expensive for the incorporation of the Selenium component in a batch of raw materials; • Access to new high Selenium glass formulas. Pellets are small pieces of material of any shape, which are at least 1 cm in their widest dimension. More often, it can be at least 0.5 cm in its widest dimension. Generally, it does not exceed 20 cm for the wider dimension. Preferably, the pellets are of parallelepiped, cubic or cylindrical shape. The pellets according to the invention are composed of two parts: a hollow cavity filled with a heart of selenium and / or at least one selenium compound and a matrix around the filled roe cavity, which hides and isolates the heart of the environment pellet. The matrix, according to the invention, is a compressed tablet that does not melt below 1300 ° C under normal atmospheric pressure. The matrix must be free of any compound which can increase to a gaseous compound when heated from atmospheric pressure to 2000 ° C. It must also be able to slowly form a eutectic product with at least one of the constituents of a batch of molten raw materials commonly used in a glassmaking process, when immersed in the batch of raw molten glass materials. The eutectic product has a melting temperature of 400 to 1800 ° C under normal pressure. The selenium heart and / or at least one Selenium compound is selected from metallic selenium, organic and inorganic salts, as well as other organic compounds comprising selenium in its molecule. In particular, the selenium compound can be selected from the selenites and the selenates. For example, it can be a selenite of an alkali metal, similar to sodium selenite (Na2Se03). The matrix can comprise any organic and inorganic compound, possibly mixed, capable of efficiently encapsulating the heart of selenium and / or selenium compound. Efficiency is intended to mean being able to cover for a time of not less than 5 or 15 minutes the presence of selenium and its component parts of batches of hot molten glass, such as Si02, CaO, Na20, K20, A1203 and the like. According to the invention, the matrix can comprise at least one of the following compounds: Si02, Na20, K20, Li20, B203, CaO, MgO, BaO, ZnO, A1203, Fe203, Se, Ti02, CoO, MnO, Cr203, Ce02, Zr02, NiO, Sn02, Cu20, V205 and S03. These compounds can be present as such in the matrix, or mixed or combined with others to form special components similar to sand, cement of any kind, dolomite and the like. Two or more of these can also be mixed together. According to one embodiment of the invention, the matrix is generally capable of forming a eutectic with one or more molten CaO, MgO, Na20, Si02 or A1203 present in a glass batch of raw material. As mentioned above, a second aspect of the invention is to provide a process for the manufacture of pellets according to claim 7. In the process: • part of the total amount of matrix material is dry mixed "the mixture is poured into a mold having an open cavity • a rod having a section slightly smaller transversal one of the cavity opening, then inserted into the cavity and allows to be placed in the matrix material mixture • the rod is then pressed with the help of a press to solidify the matrix material in a lower half pellet • the rod is removed and the selenium and / or selenium compound is deposited in the upper central area of the medium pellet • a second and last part of the amount of the mixed matrix material is poured over the selenium and / or selenium compound • the rod is placed back into place in the mold cavity and compressed • the finished pellet is removed from the mold. One embodiment of the process according to the invention consists of using two different rods, first one with a smooth section end to compress the first lower middle pellet and a second, one with a small hole located in the center of its exposed section end to maintain the selenium and / or selenium compound in the pellet core during the processing operation. In accordance with another interesting embodiment, a small portion of a binding agent can be added to the selenium and / or selenium compound before being compressed into the matrix. This has the advantage of maintaining the selenium and / or selenium compound within the finished pellets at a distance from the outer surfaces. The binding agent can be selected from any sticky, preferably organic, composition to allow its escape in the form of water vapor and C02 from the batch mixture by the action of heat. Water by itself in small amounts can also be used as a binding agent. Generally, the binding agent may be present in amounts as low as 0.05% by weight of selenium and / or selenium compound and does not exceed a small percentage of the weight. It is most often kept below 10% of the weight. The invention also relates to the use of the pellets according to the invention to incorporate a batch of molten glass to reduce the selenium burning in the exhaust gas. It also refers to a method for reducing the selenium burning in a process for manufacturing glass comprising selenium by incorporating at least part of the raw selenium material into the pellets compatible with the invention. A final aspect of the invention is to provide a glass comprising selenium, which has been manufactured by the method detailed above. In a preferred embodiment, the glass is a glass of bicarbonate lime. In another preferred embodiment, bicarbonate lime glass comprising Selenium is a supernatant glass obtained by floating a molten glass ribbon on the upper surface of a molten tin metal bath. The glass can also be, alternatively, any other type of glass that includes, without limitations: drain glass, extracted glass and blown cylinder glass. Preferably, the supernatant glass of bicarbonate lime is a smooth glass. The invention will now be illustrated below by examples which are intended to better describe the invention, without in any way attempting to limit its scope.
Example IR: (not in accordance with the invention) A first reference examples melted (Example IR) has involved a batch of raw materials that do not include pellets in everything. The following solid components have been mixed in powder form in the indicated amount: Table 1 To these components 4% of the total weight of the batch of water in liquid form is added to facilitate the mixing of the different solid components. After dry mixing of batch solids, they are poured into a ZAC crucible (zirconia-alumina), the latter is inserted for 2 hours in a laboratory furnace filled with a reductive gaseous atmosphere consisting of a mixture of 95% nitrogen and 5% hydrogen, which is It has preheated to 1400 ° C. The molten batch, which becomes a molten glass, then melts into a cold plate and the resulting solid glass breaks into small pieces. The pieces are then inserted again into a crucible and placed in the oven at 1400 ° C. The temperature is then increased to 1450 ° C at a rate of about 5 ° C / min. The molten glass is then melted, broken and inserted back into the oven at 1450 ° C. The total duration of the suspension at the temperature is approximately 2 hours. The temperature is then increased to 1500 ° C with the same ratio of 5 ° C / min. The molten glass is then maintained at the temperature by refining it for about an hour, then by a return at 1450 ° C for thermal conditioning for about 1.5 hours. At the end of the thermal conditioning period, the molten glass has been melted in small 4 cm x 4 cm steel molds, which are placed in an annealing furnace at 600 ° C for 2.5 hours. The electrical heating of the annealing furnace is then interrupted and the temperature is allowed to fall to room temperature overnight. On the following day, the glass samples are removed from the molds and their faces are mechanically polished. Its chemical composition is then analyzed by X-ray fluorescence technique and its remaining selenium yield computed by comparison with the initial amount added to the batch mixture. Selenium's performance computation gives a result of 14% Example 2R: (not according to the invention) In a second reference example (2R: mixed pellet), the composition "A" described in patent EP 0618 177 Al has been used to compress a pellet that has been inserted into the half of the solids of raw materials in the same crucible as in the IR example. The batch of raw materials and the pellet are of the following composition: Table 2: The same process of melting, refining and hardening the glass has been carried out as in the IR example. The Selenium performance measurement has been 12% for this example.
Example 3-5 (according to the invention) The same procedure as that used in example 2R has been carried out with modified pellets of three different natures. Approximately half of the batch materials are carefully pressed and have to present a hollow cavity in the middle of the compressed mixture. The last cavity was subsequently filled with 0.059 g of Na2Se03 (encapsulated selenium pellets) and covered with the remaining half of the batch materials. The complete pellet comprising the selenium compound at its center has therefore been pressed.
Table 3: Selenium yields have been computed and indicated in the bottom of the table. It can be observed that encapsulating selenium compounds within the pellets can increase the yield up to 100% compared to the references.

Claims (15)

NOVELTY OF THE INVENTION Having described the present is considered as a novelty, and therefore, what is contained in the following is claimed as property. CLAIMS
1. The pellets of at least 0.5 cm in their largest dimension encapsulating selenium and / or at least one Selenium compound, characterized in that the pellets are made of: a) a hollow cavity, located within the body of each pellet and filled with a pellet. selenium heart and / or at least one selenium compound; b) a matrix around the filled roe cavity, which covers and isolates the heart of the pellet from the environment, the matrix is a compressed tablet that does not melt below 1300 ° C under normal pressure, free of any compound which can increase to a gaseous compound when heated from atmospheric temperature to 2000 ° C and which is capable of slowly forming a eutectic product with at least one of the constituents of a batch of molten raw materials commonly used in a glass manufacturing process , when it dips into the batch of raw materials of molten glass, the eutectic product has a melting temperature of 400 to 1800 ° C under normal pressure.
2. Pellets according to claim 1, characterized in that the selenium core and / or at least one selenium compound is selected from selenium metal and organic and inorganic salts, as well as other compounds comprising selenium in their molecules.
3. Pellets according to claim 2, characterized in that the selenium compound is selected from selenites and selenates.
Pellets according to one of claims 1 to 3, characterized in that the matrix comprises at least one of the following compounds SiO2, NaO2, K20, Li20, B203, CaO, MgO, BaO, ZnO, A1203, Fe203, Se, Ti02, CoO, MnO, Cr203, Ce02, Zr02, NiO, Sn02, Cu20, V205 and S03.
Pellets according to claim 4, characterized in that the matrix comprises at least sand, cement, dolomite or any combination of two or more of these compounds.
Pellets according to any of claims 1 to 5, characterized in that the matrix is capable of forming a eutectic with one or more of CaO, MgO and Si02 fused present in a glass batch of raw material.
Process for manufacturing pellets according to any of claims 1 to 6, characterized in that: • part of the total amount of the matrix material is dry mixed • the mixture is poured into a mold having an open cavity • a rod having a slightly smaller cross section one of the cavity opening, then inserted into the cavity and allows to be placed in the matrix material mixture • the rod is then pressed with the help of a press to solidify the material matrix in a lower half pellet • the rod is removed and the selenium and / or selenium compound is deposited in the upper central area of the medium pellet • a second and last part of the amount of the mixed matrix material is poured over the selenium and / or selenium compound • the rod is placed back into place in the molded cavity and compressed • the finished pellet is removed from l mold
8. Process for the manufacture of pellets according to claim 7, characterized in that two different rods are used, first one with a smooth section end to process the lower middle pellet and a second with a small hole located in the center of its final section in view to maintain the selenium and / or selenium compound in the heart of the pellet during the processing operation.
Process for manufacturing pellets according to claim 7 or 8, characterized in that a small proportion of a binding agent is added to the selenium or selenium compound.
10. Pellet manufacturing process according to claim 9, characterized in that the binding agent is selected from at least one sticky organic composition and water.
11. Use of the pellets according to one of claims 1 to 10 to incorporate a batch of molten glass to reduce the selenium burning in the exhaust gas.
12. A method for reducing selenium burning in a process for manufacturing glass, characterized in that it comprises selenium incorporating at least part of the raw selenium material within the pellets according to one of claims 1 to 10.
13. A glass of carbonated lime, characterized in that it comprises selenium, which has manufactured by the method according to claim 12. 1.
Glass of carbonated lime comprising selenium according to claim 13, characterized in that it is a supernatant glass obtained by floating a ribbon of molten glass on the upper surface of a bath of molten tin metal.
15. A smooth glass comprising selenium, characterized in that it is the supernatant glass according to claim 14.
MXMX/A/2008/005088A 2005-10-18 2008-04-18 Pellets for se encapsulation MX2008005088A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP05109699.8 2005-10-18

Publications (1)

Publication Number Publication Date
MX2008005088A true MX2008005088A (en) 2008-09-26

Family

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