The evolution and dynamics of a dense primordial reservoir in the deep mantle influence the heat flow from the core. The fate of anomalously dense material in the mantle is significant because heterogeneous heat flux at the core-mantle boundary (CMB) can induce regional stratification at the top of the core and can determine whether a dynamo is possible. The lateral movement and configuration of dense material on top of the CMB are determined in part by comparably dense cold downwelling return flow patterns. In turn, lateral variations in heat flux are established because warm piles insulate the core and cold downwellings extract heat. The lateral extent and the amplitude of heat flux variations resulting from dense material depend on its physical properties. Experimental studies and numerical simulations have shown that the main property governing the formation of pile-like structures and their long-term stability or rapid entrainment is the chemical density contrast between dense and regular mantle materials. Secondary properties include pile enrichment in heat-producing elements (HPEs) which controls pile mean temperature (and thus its thermal buoyancy) and the thermal gradient at their base. Recently, we demonstrated that heterogeneous mantle thermal conductivity influences the thermal buoyancy and fate of piles. However, the feedback between chemical density contrast, HPEs, and thermal conductivity on CMB heat flux has not been studied. Here, we examine thermochemical mantle convection in a spherical annulus geometry to assess each property's effect on CMB heat flux.