Spent Mushroom Substrate and Electric Arc Furnace Dust Recycling by Carbothermic Reduction Method

Area of Science:

• Materials Science
• Environmental Science
• Chemical Engineering

Background:

• Circular economy principles are gaining traction for waste valorization.
• Spent mushroom substrate (SMS) is an underutilized agricultural waste in Taiwan.
• Electric-arc furnace dust (EAFD) is a significant industrial waste containing valuable metals.

Purpose of the Study:

• To investigate the feasibility of recycling SMS and EAFD simultaneously.
• To utilize SMS as a reducing agent for zinc recovery from EAFD.
• To assess the environmental benefits, including CO2 emission reduction.

Main Methods:

• Carbothermic reduction of EAFD using SMS as a substitute for metallurgical coke.
• Optimization of the carbon-to-oxygen (C/O) ratio and temperature for zinc removal.
• Torrefaction of SMS to enhance its fixed carbon content and reducing properties.

Main Results:

• A 95% zinc removal from EAFD was achieved at 1100 °C using SMS with a C/O ratio of 0.8.
• Volatile matter in SMS facilitated zinc reduction at lower temperatures and enabled a reduced C/O ratio (0.16) at 1300 °C.
• Torrefied SMS (500 °C) improved zinc productivity to levels comparable to coke, reaching ~99% removal at 1200 °C.

Conclusions:

• SMS is a viable and effective reducing agent for zinc recovery from EAFD.
• The use of SMS offers potential for lower-temperature processing and reduced energy consumption.
• This approach promotes a circular economy by transforming agricultural and industrial wastes into valuable resources.