The quartz sand roasting furnace operates based on high-temperature thermal treatment and oxidative decomposition. The working process consists of four key stages: preliminary heating and drying, high-temperature roasting, oxidative cleaning, and cooling and unloading.

1. Preliminary heating and drying stage

Loading and initial heating:

• Quartz sand is continuously or periodically loaded into the rotating drum of the furnace.
• With slow rotation of the drum, the material gradually moves into the high-temperature zone.
• The temperature in the preliminary heating zone gradually increases (200-400℃).

Moisture evaporation:

• Free moisture on the surface of the quartz sand and some adsorbed water gradually evaporate.
• Preparation of the material for high-temperature roasting.
• Prevention of material cracking due to sudden heating.

2. High-temperature roasting stage.

Temperature increase in the roasting zone:

• The material continues moving into the high-temperature roasting zone (800-1200℃).
• Burners provide a stable source of high temperature.
• The temperature control system monitors and adjusts in real time.

Optimization of the crystalline structure:

• At high temperature, internal stresses in quartz crystals are relieved.
• Partial restoration of defects in the crystal lattice.
• Improvement of the physical properties of quartz.

3. Oxidative cleaning stage.

Oxidation and decomposition of organic substances:

• At high temperature, organic substances on the surface and in cracks of quartz sand fully contact oxygen.
• Organic impurities oxidize and decompose into CO₂ and H₂O, which volatilize.
• Main reaction: Organic matter + O₂ → CO₂↑ + H₂O↑

Oxidation of iron-containing compounds:

• Fe²⁺ (yellow) oxidizes to Fe³⁺ (red).
• 2FeO + ½O₂ → Fe₂O₃
• Increase in whiteness and purity of quartz sand.

Removal of crystallization water:

• Crystallization water in minerals decomposes and is released at high temperature.
• Impurity minerals such as kaolinite undergo dehydration reactions.
• Further increase in the purity of quartz sand.

4. Cooling and unloading stage.

Temperature reduction:

• The roasted quartz sand enters the cooling zone.
• The temperature gradually decreases to below 100℃.
• Prevention of material damage from sudden cooling.

Gas removal under vacuum:

• Production under full vacuum ensures free circulation of gases.
• High-temperature gases and volatile impurities are cleaned through a dust collection system before discharge.
• Almost complete absence of dust emissions, environmentally friendly.

Unloading of the finished product:

• The cooled quartz sand is unloaded through the discharge end.
• Sealing devices prevent dust leakage.
• Obtaining the finished product — quartz sand of high purity and whiteness.