Silica Separation Methods
Physical Separation Technology
Physical separation is one of the most widely used silica recovery methods. It primarily uses mechanical forces to break the bond between rubber and silica. Common methods include:

Mechanical Crushing: Scrap rubber is physically crushed using shears, double-roll mills, ball mills, and other equipment. After grading and screening, it can be used directly as a filler or after modification.

Low-Temperature Crushing: Brittles the rubber at low temperatures, facilitating subsequent crushing and separation.
Kneading: Mechanically kneading separates the rubber from the filler.
Elastic Deformation: Utilizes the elastic properties of rubber to achieve separation.

The advantages of physical separation are simplicity, ease of operation, and the relatively simple process, resulting in high-quality regenerated silica. However, disadvantages include uneven particle size distribution and low surface activity, which may not meet the requirements of some industries with high silica quality requirements.

Chemical Separation Technology
Chemical separation uses chemical reactions to separate silica from waste rubber:

Thermal Cracking: The rubber, carbon black, and steel wire in waste tires are decomposed by heating under oxygen-deficient conditions, converting them into useful fuels and chemicals.

Solvent Extraction: Silica is separated from the waste using a solvent and recovered through filtration and evaporation. The solvent is also recovered and reused.

Acid Leaching/Alkali Dissolution: High-temperature calcination, acid leaching, and alkaline dissolution are used to remove oil and colored metal oxides from the residue, resulting in a relatively pure sodium silicate solution. Silica is then produced using a sol-gel method.

The advantage of chemical separation is the ability to produce higher value-added products, such as new rubber reinforcing agents. However, the disadvantage is the complexity and high cost of the chemical reaction process.

Silica Recycling Technology
Applications in the Rubber Industry
Separated silica has a wide range of applications in the rubber industry:
Tire Manufacturing: Silica is used in tire tread and carcass rubber to improve tear strength and rubber-cord adhesion.
Retreading: Silica as a filler can reduce tire rolling resistance and improve fuel efficiency.
Rubber Products: In rubber products such as shoes and tires, silica can improve hardness, tensile strength, tear strength, and abrasion resistance.
Other Applications
Building Materials: Silica can improve the material's high-temperature and radiation resistance, making building materials more durable and fireproof. and safety

Electronic Materials: Silica can be used in chip packaging materials, requiring high purity and high dispersibility.
Coatings Industry: Silica can improve coating strength, glossiness, and pigment suspension.

Future development trends include:
Developing more efficient and environmentally friendly separation technologies to reduce energy consumption and environmental pollution.

Increasing silica recovery rates and purity to meet high-end application requirements.
Expanding silica's applications in emerging fields such as new energy and electronic materials.
Establishing a comprehensive recycling industry chain to achieve large-scale production and commercial applications.

With continuous technological advancement and policy support, the recycling of silica from waste rubber will make a significant contribution to achieving a circular economy and sustainable development.