In some variations, the invention provides a biocarbon composition comprising a low fixed carbon material with a fixed carbon concentration from 20 wt % to 55 wt %; a high fixed carbon material with a fixed carbon concentration from 50 wt % to 100 wt % (and higher than the fixed carbon concentration of the low fixed carbon material; from 0 to 30 wt % moisture; from 0 to 15 wt % ash; and from 0 to 20 wt % of one or more additives (such as a binder). Some variations provide a process for producing a biocarbon composition, the process comprising: pyrolyzing a first biomass-containing feedstock to generate a low fixed carbon material; separately pyrolyzing a second biomass-containing feedstock to generate a high fixed carbon material; blending the low fixed carbon material with the high fixed carbon material, thereby generating an intermediate material; optionally, blending one or more additives into the intermediate material; optionally, drying the intermediate material; and recovering a biocarbon composition containing the intermediate material or a thermally treated form thereof.