Iron separation by magnetic separation of household waste incineration bottom ash in Seoul

The incineration rate of combustible household waste discharged using standard waste bags in Seoul city increased by about 6 times compared to about 20 years ago, reaching 58% as of 2022. From 2018 to 2022, the waste metals mixed in standard waste bags of Seoul city are the source of incinerated-iron, the discharge of which increases every year. However, the proportion recovered as incinerated-iron is varied, ranging from 4.7% to 39.7%, and the recovery rate is decreasing over the years. The proportion of incinerated-iron recovered from bottom ash is 1.2% to 2.1%, and the proportion of incinerated-iron among the recovered metals is 94.3% to 99.6%. All recovered incinerated-iron is sold, but its price is lower than the market price. The low recovery rate and low selling price are the current problems of incinerated-iron of Seoul. The recovery rate can be affected by the type of incoming waste, the performance of the magnetic separator, and the size and shape of incinerated-iron, and continuous research is needed to analyze these interrelationships. In addition, the low sales price of incinerated-iron is related to its quality and use. Incinerated-iron is recovered as iron oxide and sold with the incineration bottom ash still on the surface, greatly reducing usage. Future research is needed to improve the recovery quality of incinerated-iron and expand its uses.