MACHINE PROCESS

Glass Manufacturing Machine Process

Glass Manufacturing Machine Process

Introduction

The research describes the manufacture machine process of flat glass and pressed and blown glass. Flat glass encompasses plate and architectural glass, automotive windscreens, and mirrors. Pressed and blown glass encompasses containers, machine-blown and hand-blown glassware, lamps, and television tubing. In both categories, a glass melt is prepared from silica sand, other raw materials for example lime, dolomite, and soda, and cullet (broken glass). The use of recycled glass is increasing. It decreases the consumption of both raw materials and energy but necessitates extensive sorting and cleaning prior to batch treatment to remove impurities (Bounicore, 2002).

For the manufacture of special and technical glass, lead oxide, potash, zinc oxide, and other steel oxides are added. Refining agents encompass arsenic trioxide, antimony oxide, nitrates, and sulfates. Metal oxides and sulfides are utilized as coloring or decoloring agents (Sittig, 2005).

Discussion

The most common furnace utilized for manufacturing glass melt is the continuous regenerative type, with either the side or the end ports connecting brick checkers to the inside of the melter. Checkers conserve fuel by portraying as heat exchangers; the fuel combustion goods heat incoming combustion air. The molten glass is perfected (heat conditioning) and is then pushed, blown, drawn, revolved, or rode high, counting on the last product. Damaged and broken product (cullet) is returned to the process (Economopoulos, 1999).

The most important fuels for glass-melting furnaces are natural gas, light and heavy fuel oil, and liquefied petroleum gas. Electricity (frequently established as supplementary heating) is furthermore used. Energy requirements range from 3.7 to 6.0 kilojoules per metric ton (kJ/t) glass produced.

Waste Characteristics

Two kinds of air emissions are generated: those from the combustion of fuel for operating the glass-melting furnaces, and fine particulates from the vaporization and recrystallization of materials in the melt. The major emissions are sulfur oxides (SOx), nitrogen oxides (NOx), and particulates, which can comprise heavy metals for example arsenic and lead. Particulates from lead crystal manufacture can have a lead content of 20-60% and an arsenic content of 0.5-2%. Certain specialty glasses can produce releases of hydrogen chloride (HCl), hydrogen fluoride (HF), arsenic, boron, and lead from raw materials. Container, pressing, and blowing operations produce a periodic mist when the hot gob comes into contact with the release agent utilized on the molds.

Cold-top electric furnaces, in which the melt surface is covered by raw material feed, release very little particulate matter, as the blanket acts as a filter to prevent the release of particulate matter. Some releases of particulates will take place in tapping, but furnace releases should be of the order of 0.1 kilogram per ton (kg/t) when operated this way.

Lead glass manufacture may result in lead emissions of about 2-5 kg/t. In all cases, the concentration of heavy metals and other pollutants in the raw flue gas mainly depends on the kind of fuel used, the composition of the feed material, and the portion of recycled glass. High input of sulfates or potassium nitrate may boost ...