Abstract: A process for carbonizing lignite coal in a Herreshoff Carbonizer of a multi-hearth type. The novel process comprises the steps of introducing given quantities of lignite in the first and succeeding hearths while introducing sufficient quantities of combustion air and fuel to ignite the fuel and to raise the temperature of the hearths until the process is self-sustaining as a result of the combustion of the volatiles driven off of the lignite. The hearth temperatures range approximately 1450.degree. to 1620.degree. F in the first furnace hearth with the second furnace hearth ranging approximately 1650.degree. to 1800.degree. F and the third furnace hearth ranging approximately 1650.degree. to 1890.degree. F. Sufficient combustion air is introduced into various hearths of the furnace to insure complete combustion in at least the first hearth and in the stack of the volatiles being driven off thereby making the process self-sustaining, allowing the introductory fuel to be cut off.