Carbonization of oil palm empty fruit bunch (OPEFB) biomass for the production of high mineral content biochar under an uncontrolled carbonization temperature and controlled air flow rate was studied using a pilot-scale brick carbonization reactor. The maximum temperature during the carbonization process was found to be in the range of 543 to 564 oC at exhaust gas flow rate of 36 m3/hr. All minerals (i.e P, K ,Mg, Ca, Na, Mn, Fe, Cr, AI) showed an increased from the feedstock concentration up to 300 %. The concentration of heavy metal extracted from OPEFB biochar was lower than listed ceiling permitted levels. This proposed system without electrical control and heating source is preferable to the industry due to its simplicity, ease of operation and low energy requirement making it suitable for OPEFB biochar production for mulching purposes with more than double the mineral content compared to raw OPEFB biomass
