Vertical screw-feed blenders for mixing granules or powders in medium and large quantities. Made in carbon steel, painted with epoxy resins, or alternatively in AISI 304 STAINLESS steel, accurately brushed and finished inside and with large inspection hatches, these machines are ideal for clients who wish to blend products to obtain a homogeneous compound. The materials are loaded manually from a large hopper, or automatically using feeding screws for forced load, vacuum feeders or granule launchers, or discharge big-bags or octabins directly into the hopper. A series of optional devices is provided to discharge the material into big-bags and heat it during blending. An optional opening on the inner pipe makes the machine very quick and easy to clean.