# Preparation, Properties and Chemical Modification Methods of the Fire-Fighting Foam for Coal Spontaneous Combustion

## TL;DR

This paper reviews fire-fighting foam materials to prevent coal spontaneous combustion, focusing on their preparation, properties, and chemical modifications.

## Contribution

The paper introduces coal gasification slag as a new foam component and emphasizes the need for environmentally friendly and effective fire-fighting foams.

## Key findings

- Three-phase, gel, and curing foams are analyzed for their inhibition mechanisms against coal spontaneous combustion.
- Environmental friendliness and anti-fire performance are key factors for future foam material development.
- Coal gasification slag is proposed as a new, sustainable component for fire-fighting foams.

## Abstract

Coal spontaneous combustion causes both human casualties and environmental pollution. Owing to special flow behaviors, foam materials used in fire-fighting technology can effectively bring water and solid non-combustible substances into the fire-fighting area, greatly preventing spontaneous combustion. This paper systematically elucidates three foam materials, three-phase foam, gel foam and curing foam, and analyzes their physical and chemical inhibition mechanisms on coal spontaneous combustion. In particular, the preparation, performance and latest chemical modification methods of the foam materials are summarized in detail. It is found that foam materials with environmental friendliness, economy and excellent anti-fire performance need to be consistently explored. The primary application areas for cement-based foamed materials remain the building materials and civil engineering industries, and their modification should be studied accordingly based on the specific application context. Furthermore, a new component of foam materials, coal gasification slag (a solid waste), is proposed. In addition, the seepage properties of fire-fighting foam in porous media should be fully studied to accurately grasp the dispersion of foam materials in mine goafs. This review provides new insights and guidance for the development of fire-fighting foam materials.