Negative emissions technologies (NETs) play an important role in mitigating climate change as these technologies reduces the amount of CO2 in the atmosphere. Among various NETs, enhanced weathering is regarded as an optimistic method for carbon sequestration. Enhanced weathering is a process of spreading crushed mineral rocks on soil to react with atmospheric CO2 which then accelerates carbon fixation. If implemented commercially via carbon management network (CMN), this technology offers the possibility of carbon sequestration from the atmospheric emissions at the range of several gigatons per year (Gt/y CO2). Crushed mineral rock size is a significant factor influencing the efficiency of carbon sequestration in enhanced weathering. However, there is limited mathematical optimization research that considers crushed mineral rock sizes for optimal enhanced weathering network. In this work, a linear programming (LP) model that take in consideration of different crushed mineral rock sizes is developed to determine the optimal enhanced weathering based-CMN. A case study on enhanced weathering based-CMN is solved to demonstrate the applicability of this technique.