The Use of Coffee Waste in the Reduction of Metallurgical Slags

Abstract

Coffee is grown in over 50 countries around the world, and its sale is the largest in the world trade after crude oil. In the case of coffee beans, after consumption remains a solid waste in the form of a waste plant extract. At present, coffee waste is not fully managed, which means that it is often deposited in landfills. Taking into account their availability on the market and the content of significant amounts of carbon in them, it was proposed to use them as a reducing agent in the processing of copper slags. The use of Solid Coffee Grounds (SCG) as an alternative reducing agent for coke and coke breeze can be beneficial in two aspects. The first is the reduction of carbon dioxide emissions in the process, and the second is due to the possible release of hydrocarbons from these wastes at high temperatures, which, apart from participating in the reduction process itself, causes also mixing of the bath in the melting unit, which facilitates the process of copper sedimentation in the slag. The experiments carried out on a laboratory scale showed the possibility of reducing the copper content in the slag after the reduction process from 10.3 to 0.41 % by mass. The obtained values of the relative degree of copper splashing for all experiments ranged from 88.4 to 96.0 %. The presented solution is an innovative approach to the use of SCG in the processing of copper slags.

Keywords

• solid coffee grounds
• reduction
• copper slag
• calorimeter