Environmental conservation and safety
Ceramic work has real hazards. Good factories control each one.
- Dust: clay, quartz and glaze dust. Fine silica dust can scar the lungs (silicosis). Control: wet cleaning (not dry sweeping), local exhaust fans with filters, and a dust mask or respirator.
- Heat and fire: kilns are very hot. Use insulation, gloves, safe distance and fire rules.
- Noise: mills and crushers are loud. Use ear protection.
- Chemicals: some glazes have metals such as lead or cadmium. Use safe glazes, gloves and wash hands. Keep food away from work areas.
- Kiln gases: CO2, CO, sulphur and nitrogen oxides, fluorides. Good burners, enough air, and filters or scrubbers reduce them.
Conservation means using less energy and raw material: good insulation, heat recovery from hot exhaust, efficient kilns and saving water.
Waste treatment
Waste can be in air, water or solid form. Each has a treatment.
- Air: a bag filter works like a vacuum cleaner bag and traps dust. A scrubber sprays water or liquid to wash out gases. An electrostatic precipitator charges dust so it sticks to plates.
- Water: wash water with clay goes to a settling tank. Solids sink as sludge, which is pressed dry in a filter press. Acids or alkalis are neutralised. The clear water is reused.
- Solid: sludge and scrap. What cannot be reused goes to a safe landfill, as the last choice.
The order of preference is reduce, reuse, recycle, dispose.
Recycling technology
Green scrap (unfired pieces) can be soaked in water and turned back into slip. Fired scrap (broken ware) is crushed and ground into grog. Grog is added to new clay bodies; it also reduces shrinkage and cracking. Some ceramic waste is used in bricks, tiles and road base.
In glass making, broken glass called cullet is melted with the batch. It melts at lower temperature and saves energy and raw material.
Simple sums: recycled mass = scrap × recycled share, and new raw material = batch − recycled mass.
Key formulas and definitions
- Recycled mass = scrap mass × (recycled % ÷ 100)
- New raw material = batch mass − recycled mass
- Landfill = scrap mass − recycled mass
- Removal efficiency % = (amount in − amount out) ÷ amount in × 100
- Reduce → Reuse → Recycle → Dispose
Worked examples
1. A 100 kg batch makes 20 kg of scrap. 60% of the scrap is recycled. How much goes to landfill?
Recycled = 0.60 × 20 = 12 kg. Landfill = 20 − 12 = 8 kg.
2. A bag filter takes dust from 50 mg/m³ down to 5 mg/m³. Find its efficiency.
(50 − 5) ÷ 50 × 100 = 90%.
3. A plant uses 1000 L of water per day and reuses 80%. How much fresh water is needed?
Reused = 800 L. Fresh = 1000 − 800 = 200 L.
4. A settling tank holds 40 kg of solids and removes 95%. How many kg remain in the water?
Removed = 0.95 × 40 = 38 kg. Remaining = 2 kg.
5. A 100 kg batch reuses 12 kg of grog. Raw material costs ₹5 per kg. How much is saved per batch?
12 × ₹5 = ₹60 per batch.
6. A 1000 kg glass batch uses 30% cullet. How much new raw material is needed? (simple model)
Cullet = 300 kg. New raw material = 1000 − 300 = 700 kg.
Common mistakes
- Dry sweeping dust. It lifts fine particles into the air. Clean with water or a vacuum with a filter.
- Thinking a thin paper mask is enough for fine silica dust. Use a proper respirator.
- Throwing scrap away. Most ceramic scrap can become grog or filler.
- Treating landfill as the first choice. It is the last step after reduce, reuse and recycle.