The global transition toward clean energy technologies has triggered an unprecedented demand for critical minerals, including lithium, cobalt, nickel, and graphite. Sub-Saharan Africa holds roughly 30% of the world's critical mineral reserves, positioning the continent at the epicenter of this resource boom. However, historical patterns of commodity-dependent extractivism have continuously trapped African economies in the upstream segment, exporting cheap raw ores while importing expensive refined components. This study evaluates the economic and structural constraints hindering midstream domestic processing within African borders. Using a mixed-methods approach comprising econometric modeling of macroeconomic data from 12 mineral-rich African nations and a comprehensive comparative policy review, this paper assesses how localized value addition affects national GDP growth, fiscal revenue, and employment trends. The results demonstrate that implementing domestic processing mandates, backed by localized infrastructure investments, could increase continental GDP by approximately 12% and unlock over 2.3 million industrial jobs. The study concludes that regional supply chain integration under the African Continental Free Trade Area (AfCFTA) is essential to overcome domestic power and logistical deficits.