Coal mine wastes recycling for coal recovery and eco-friendly bricks production

Abstract

The mining industry is globally criticized for generating large amount of solid wastes often with a potential environmental impact. This study presents a feasible approach of recovering residual coal from coal mine waste rocks (CMWR) and reusing the derived tailings to produce ecofriendly fired bricks. The first step aims at the production of high grade anthracite coal concentrate using a physical treatment method which consists of consecutive stages of crushing, grinding and froth flotation. Coal (organic matter) was recovered in order to enhance the mechanical strength of bricks and to reduce the greenhouse gas (GHG) emissions during the firing process. The second step of the process consists of the mixture of the decarbonated tailings, called treated coal mine tailings (TCMT), with a small amount of water, pressed and fired at an optimal temperature of 1020°C for the production of ecofriendly bricks at a laboratory scale. Fired bricks containing no other raw materials than CMWR or its derived TCMT have been produced showing in both cases very interesting ornamental looks. The study assessed the effects of removing coal from CMWR on the physical and technical properties of the derived fired bricks. The removal of coal from CMWR enhanced the quality of fired bricks by increasing its flexural strength and decreasing the open porosity and water absorption. In addition, the results show that this integrated process reduces the amount of GHG emissions by more than 70% and allows a sustainable production of fired bricks.