Study on the Valorization of Used Waste Oils as Fuel for the Firing of Clay Bricks in an Artisanal Kiln

Used engine oil is a main source of oil contamination of waterways and can result in pollution of drinking water sources. Insoluble, persistent, slowly dergradable, it can contain toxic chemicals and heavy metals. Animals and birds from the polluted oil soil can be stuck. The present study aims to contribute to solving the environmental problem and energy saving purpose by recovering waste from the recycling of used oil to improve the firing of clay bricks. The waste from recycling used oil is collected and mixed with wood charcoal. This mixture is used as fuel in the artisanal kiln to fire the bricks. The temperature rises in the kiln, the cooling time and the quality of baked Clay Bricks are analyzed. The maximum temperature observed inside the kiln is 900°C in 36 hours of kiln operation when wood charcoal is used as fuel with a firing time of five (5) days and 1020°C in 80 hours when wood charcoal and “Chinese coal” (waste from the recycling of used oil) are used as fuel with a firing time of ten (10) days. This explains the longer cooling time than with wood charcoal alone as fuel. The firing of the bricks is perfect with both fuels, whereas, with wood charcoal alone as fuel, 15% of the bricks are unbaked. The bricks also have a very clean appearance. They have an average shrinkage of 1%, which is lower than the normative value of 3%, the average compressive strength is 16.5MPa which is higher than the normative value of 12.5MPa, and the water absorption is 40% which is lower than the normative value of 60%. 
This combination of fuels reduces the use of wood charcoal, which in turn reduces deforestation and prevents air pollution and soil degradation through the dumping of waste oil in the environment.