Here is a clear, professional English introduction to the production process differences between modified kaolin and calcined kaolin:
Core Production Process Differences Between Modified Kaolin and Calcined Kaolin
Calcined kaolin is a semi-finished intermediate product, while modified kaolin is a further deep-processed high-value product based on calcined or pretreated kaolin. Their process routes, technical focuses and final product properties have clear distinctions:
1.Process Positioning & Core Purpose
Calcined Kaolin: It is a single thermal activation process. The core goal is to remove structural hydroxyl groups, organic carbon and volatile impurities in raw kaolin through high-temperature calcination, so as to improve product whiteness, activity and basic physical properties.
Modified Kaolin: It is a full deep-processing process. It usually uses qualified calcined kaolin or pretreated raw kaolin as the base material, and carries out targeted structural transformation and surface functionalization on this basis, to meet the specific performance requirements of different industrial scenarios.
2.Key Process Parameters & Operation Details
Calcined Kaolin: The core control link is the calcination temperature. Different application scenarios correspond to different fixed temperature ranges: 700℃ for metakaolin for molecular sieve synthesis, below 850℃ for PVC cable filler, 1000℃ for papermaking coating, and 1300–1525℃ for high-grade refractory raw materials. No additional chemical reagents are added during the whole process.
Modified Kaolin: It does not focus on a single fixed calcination temperature. After the conventional calcination activation step, it will add targeted modification units: silane coupling agent surface coating, acid/alkali leaching to adjust pore structure, intercalation agent to expand interlayer spacing, etc. A variety of specific chemical modifiers are introduced in the process.
3.Post-Processing Flow
Calcined Kaolin: After the calcination step, it only needs simple procedures such as depolymerization, crushing, air classification and packaging to obtain the finished product, with a short process flow.
Modified Kaolin: After the modification reaction, it must go through additional steps such as washing, filtering, secondary drying, deagglomeration and precise classification, to remove unreacted residual reagents and ensure the stability of surface modification effect. The whole process flow is longer and more refined.
4.Final Process Output Characteristics
Calcined Kaolin: The product only changes in basic physical properties such as whiteness, particle size and specific surface area, and no new functional groups are introduced on the particle surface.
Modified Kaolin: On the basis of the basic properties of calcined kaolin, new active sites, hydrophobic groups or specific functional structures are added to the product, which greatly improves the compatibility with polymer materials, adsorption performance and other targeted application properties.