# Hydrometallurgical recycling of steel grinding swarf via oxidative leaching using ferric chloride

## TL;DR

This paper presents a new hydrometallurgical method to recycle steel grinding swarf using ferric chloride, improving metal recovery and sustainability.

## Contribution

A novel oxidative leaching process using ferric chloride is introduced for efficient and safer recycling of steel grinding swarf.

## Key findings

- Ferric chloride leaching recovered up to 94% of iron from grinding swarf in one hour.
- The process avoids flammable hydrogen production and bypasses lubricant barriers on steel surfaces.
- Produced iron chloride solutions have potential applications in water treatment.

## Abstract

Grinding swarf is a hazardous waste generated in hundreds of thousands of tons and currently has limited options for recycling. It is an environmental and economic burden for the manufacturing industry and new recycling processes are necessary for sustainable waste management. Ferric chloride (FeCl3) is an oxidant which can be used to extract metals from steel scrap to produce ferrous chloride (FeCl2) solutions. This was applied for recycling of grinding swarf containing 64% mostly metallic Fe by dissolving it in concentrated FeCl3. Optimization of leaching conditions showed that up to 94% of Fe was recovered as FeCl2 within 1 h of leaching with FeCl3, but that reaction temperature was difficult to control due to highly exothermic reactions. In contrast, classical leaching with hydrochloric acid only recovered 41% Fe from swarf in 2 h and forms large volumes of flammable H2. This improvement in efficiency was attributed to the leaching mechanisms of FeCl3 which are kinetically superior and capable of circumventing lubricant components which otherwise protect the steel surface. These findings contribute to the development of a safe recycling process for valorisation of grinding swarf. Production of iron chloride solutions with applications in water treatment promotes recycling and reduces incineration and landfilling of this waste.

Recovery of iron from waste grinding swarf from manufacturing by production of iron chloride solutions with applications in sustainability areas.