Raw materials glassmaking.
Basically, the raw material of glass consists of three types, each of which has a role in the quality and outcomes of glass products as a whole. These parts are :Glass forming materials.
The raw material of this type consists of:Quartz sand / silica SiO2 purity 99.1 - 99.7%
Sodium carbonate / soda ash (Na2CO3)
Boric acid / borax
phosfor pentaoksida
Dolomite (CaCO3.MgCO3)
Feldspar, with a molecular formula R2O.Al2O3.6SiO2 where R2O represents K2O or Na2O or a combination of both.
Cullet, the shards of glass or glass that comes from not qualifying product quality control. Cullet serves to lower the melting temperature of the raw material. Cullet is fed as much as 25% of the total raw material.
Stabilizer material, a material which can reduce the solubility in water, resistant to other chemicals including other materials contained in the atmosphere. Examples of stabilizer materials commonly used in the glass industry is
calcium carbonate, making the end product is insoluble in water.
barium carbonate, increasing the specific gravity and refractive index.
lead oxide, making the product becomes transparent, shiny, and has a high refractive index.
Zinc oxide.
Making glass is resistant to sudden heat, improves the physical and mechanical properties, and increase the refractive index.aluminum oxide, increasing the viscosity of the glass, physical strength, and resilience against chemicals.
Secondary components, among which are :
Refining agent.
Eliminate gas bubbles on melting raw materials. Materials commonly used as a refining agent in glass industry is sodium nitrate and sodium sulfate or arsenic oxide (As2O3).Color remover (decolorant).
Eliminate color is usually caused by the presence of iron oxide compounds that enter with the raw material. Materials used color remover is manganese dioxide (MnO2), metal selenium (Se), or nickel oxide (NiO).Dye (colorant).
Used to make special glasses in accordance with the desired color.Opacifiers.
Materials used as an opacifier is fluorite (CaF2), cryolite (Na3AlF6), sodium fluorosilika (Na2SiF6), tin phosphate, zinc phosphate (Zn3 (PO4) 2), and calcium phosphate (Ca3 (PO4) 2).The process of making glass.
The process of making glass in the industry include the following stages :
Raw material preparation (batching).
At this stage of milling, sifting raw materials as well as the separation of impurities-impurities. The powder is weighed according to the composition of raw materials, including other necessary additives such as dyes or substances in accordance with the glass in the desired product. Stirring the mixture of raw materials in a mixer is done so that the mixture became homogeneous before it melted.Disbursement (melting / fusing).
Raw materials that have been homogenized, sieved before putting into the furnace (furnace) temperature of about 1500oC so that the mixture will melt. During the melting process, each raw material will interact to form the following chemical reactions:Decomposition reactions:
Na2SO3 Na2O + CO2 ... .. (1)
CaCO3 CaO + CO2 ... .. (2)
Na2SO4 Na2O + SO2 ... .. (3)
CaO + MgO + MgCO3.CaCO3 2CO2 ... .. (4)
The reaction between SiO2 with Na2CO3 at a temperature of 630 - 780oC
Na2O.aSiO2 aSiO2 Na2CO3 + CO2 + ... .. (5)
The reaction between SiO2 with CaCO3 at a temperature of 600oC
CaCO3 + CO2 + bSiO2 CaO.bSiO2 ... .. (6)
The reaction between CaCO3 with Na2CO3 at temperatures below 600oC
CaCO3 + Na2CO3 Na2Ca (CO3) 2 ..... (7)
The reaction between Na2SO4 with SiO2 at 884oC temperature
Na2SO4 + nSiO2 NaO.nSiO2 + SO2 + 0.5O2 ... .. (8)
The main reaction
bNa2O aSiO2 + + + dMgO aSiO2.bNa2O.cCaO.dMgO cCaO ... .. (9)
Furnace as a dilute mixture of glass raw materials, divided into three types, namely :
Pot furnace.
Usually used to produce glass-glass (special glass) such as art glass, optical glass with a small-scale production of about 2 tons or less. Pot is made of silica-alumina brick (clay) special or platinum.Tank furnace.
Used in large-scale industrial glass and brick refractory (heat resistant bricks). Furnace is able to accommodate about 1350 tons of liquid glass that form a pool in the heart of the furnace.Regenerative furnace.
Formation (forming / shaping).Glass material is a liquid then flows into the tools that are used to form a solid glass as desired. There are several types of glass formation process, among which are:
Fourcault process.
The molten material flows vertically upward through a section called "debiteuse". This section is floating on the surface of the molten glass with a gap corresponding to the desired thickness of the glass. At the top there is a section debiteuse circulating cooling water will cool the glass up to 650 - 670oC. At that temperature the glass turns into a solid plate and will move supported by the wheel (roller) that draw the glass to the top. The figure below depicts the scheme Fourcault process.Colburn process (Libbey-Owens)
If the process Fourcault, glass movement takes place vertically, then the process will move the glass Colburn vertically followed horizontal movement after passing through the wheels brace that form molten glass into sheets.Pilkington process (float process)
Molten material flowed into a pool of liquid tin (Sn) heat. The flow rate of the liquid material is regulating the thickness of the glass sheet to be processed. Glass will float on the liquid tin due to the density difference between the two. Glass is still a liquid with heat supply from the burner at the top of the pond. Controlling the temperature in the pool is done in order to keep the glass flat on both sides and parallel. Biaanya Materials used for this purpose is a pure nitrogen gas. Furthermore, the glass flow through the area of cooling (still in the pool) and exit in the form of flat glass temperature of 600 degrees C. The process of a - c above is known as a mechanical process.Process inflatable (blow).
This process is used to make glass bottles, glass packaging, or various other forms of glass art.1. Annealing.
The function of this stage is to prevent tensions between molecules on uneven glass which can cause breakage. Glass annealing process consists of two activities:(1) Hold the glass with enough time above a certain temperature criticism for lowering the internal strain,
(2) glass Cooling to room temperature slowly to hold the stretch to the point of maximum
This process takes place in the "annealing Lehr". For this type of sheet glass, annealing Lehr is bypassed by the glass which moves on wheels running.
2. Finishing and quality control (Quality Control)
Some of the final settlement in the glass industry is cleaning and polishing, cutting, enameling, and grading.Thank you for reading this article. Written and posted by Bambang Sunarno. sunarnobambang86@gmail.com
author:
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name: Bambang Sunarno.
http://www.faradice.blogspot.com/2014/12/glassmaking.html
DatePublished: December 08, 2014 at 10:20
Tag : Glassmaking.
Code : 42S4EUXRR3UM
