a process of manufacturing powdered coffee carbons from spent coffee grounds comprising washing spent coffee grounds , dehydrating same , and conveying same to a pre - carbonation oven for drying and pre - carbonization ; removing the pre - carbonized spent coffee grounds , soaking same in a solution mixed with a predetermined quantity of sodium carbonate for a predetermined period of time for grease removal , and washing the grease free spent coffee grounds ; pouring the pre - carbonized spent coffee grounds into a post - carbonization oven and heating same to the range of 600 to 650 ° c . to carbonize the pre - carbonized spent coffee grounds wherein the carbonized spent coffee grounds have a porous structure ; supplying saturated steam between 850 and 950 ° c . to the carbonized spent coffee carbons for activation ; and operating a wet global grinder to grind the activated spent coffee carbons until powdered coffee carbons having a size between 0 . 1 and 20 μm are obtained .