PROCEDURE OF PREPARATION OF LIGHT GRANULATIONS

A two-stage heat treatment process effectively addresses the issue of non-compliant aggregates by reducing leachable fractions and pollutants, producing decontaminated and depolluted aggregates suitable for construction and public works, with reduced energy consumption and environmental footprint.

FR3129391B1Active Publication Date: 2026-04-03SEEGEX
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Patent Information

Application Number
FR2021012330
Authority / Receiving Office
FR · FR
Patent Type
Patents
Current Assignee / Owner
Filing Date
2021-11-22
Publication Date
2026-04-03
Estimated Expiration
2041-11-22

AI Technical Summary

Technical Problem

Existing processes for manufacturing lightweight aggregates from clay-based mixtures do not produce aggregates that conform to regulatory standards, particularly due to excessive leachable fractions of chemical compounds and pollutants, exceeding concentration thresholds set by NF X 30-402-2.

Method used

A two-stage heat treatment process is employed, involving a first sub-step under a reducing atmosphere at 900 to 1200°C and a second sub-step under an oxidizing atmosphere at 1050 to 1300°C, followed by cooling, to eliminate leachable fractions and decontaminate the aggregates.

Benefits of technology

The process significantly reduces the concentration of leachable elements and pollutants below regulatory thresholds, producing decontaminated and depolluted aggregates suitable for various applications, including construction and public works, while being energy-efficient and reducing environmental impact.

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Abstract

The present invention relates to a process for preparing lightweight clay-based aggregates, said aggregate being suitable for use in public works, particularly road construction, and building construction. The invention thus has as its first object a process for preparing lightweight aggregates comprising at least the following steps: a) a step of granulating a clay-based mixture to obtain aggregates, b) a step of drying the aggregates obtained to obtain dried aggregates, c) a step of heat treatment of the dried aggregates, said step comprising two successive substeps: i) a first substep of heat treatment carried out under a reducing atmosphere at a temperature T1 between approximately 900 and 1200°C, ii) a second substep of heat treatment carried out under an oxidizing atmosphere at a temperature T2 between approximately 1050 and 1300°C, and d) a step of cooling the aggregates.
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