Float Glass Manufacturing Process & Raw Material R...

Float Glass Manufacturing Process & Raw Material Ratios Float glass is the most common form of flat glass used in windows, mirrors, architecture, and automotive sectors. The 'float' process allows glass to be formed in large, uniform sheets by floating molten glass on a bed of molten tin. 🧪 Raw Materials Used in Float Glass Manufacturing Raw Material Function Approximate Ratio (%) Silica Sand (SiO₂) Main glass-forming component 68–75% Soda Ash (Na₂CO₃) Lowers melting temperature 12–15% Limestone (CaCO₃) Improves chemical durability 8–10% Dolomite (CaMg(CO₃)₂) Adds magnesium, increases stability 3–5% Alumina (Al₂O₃) Improves viscosity and strength 1–2% Feldspar Source of alumina and alkalis 1–2% Recycled Glass (Cullet) Reduces energy consumption 10–30% (varies) Colorants (optional) For green/blue/bronze tinting Trace amounts 🔁 Chemical Reactions in the Furnace During heating (at ~1, 500°C), the raw materials react as follows: Na₂CO₃ + SiO₂ → Na₂SiO₃ + CO₂ CaCO₃ → CaO + CO₂ CaO + SiO₂ → CaSiO₃ Other oxides form silicates These reactions produce molten glass, which is shaped using the float method. 🔄 Step-by-Step Float Glass Manufacturing Process 1. 🔄 Batch Mixing All raw materials (sand, soda ash, limestone, etc.) are accurately weighed, mixed, and fed into the furnace. 2. 🔥 Melting Furnace (~1500°C) Raw material melts into a homogeneous, bubble-free molten glass over 24–48 hours. 3. 🪔 Tin Bath (Floating Process) The molten glass flows onto a bath of molten tin. Gravity and surface tension cause the glass to spread evenly, forming a flat, smooth surface. Thickness is controlled by speed and temperature (typically 3 mm to 19 mm). 4. 🌡️ Annealing Lehr The glass is slowly cooled in a controlled annealing zone (~600°C to room temp). This removes internal stresses and avoids cracks or warping. 5. ✂️ Cutting & Inspection The glass ribbon is cut into sheets. Edge trimming, polishing, inspection for quality defects. Defective glass is recycled back as cullet. 📊 Output & Product Formats Thickness Range Use Case Example 3–6 mm Windows, mirrors, furniture 8–12 mm Façades, partitions, doors 15–19 mm Structural glass, aquariums, railings 🌿 Sustainability in Float Glass Industry Up to 30% cullet (recycled glass) used Energy-efficient furnaces reduce carbon footprint Emission control systems used for NOₓ, SO₂, and particulate matter 🏭 Major Float Glass Manufacturers in India Manufacturer Location Saint-Gobain Glass Tamil Nadu, Gujarat Asahi India Glass Roorkee, Gujarat Gold Plus Glass Roorkee, Vadodara Gujarat Guardian Ltd. Ankleshwar, Gujarat HNG Float Glass Halol, Gujarat