Some embodiments herein disclose a process for producing an ethylene polymer or copolymer which contains less than 5 ppm titanium and has a bulk density, in granular form, of at least 22.5 lbs/ft3, using a spheroidal Ziegler-Natta type olefin polymerization catalyst having a particle size distribution characterized by a Dm*/Dn of less than 3.0 and comprising a titanium compound, an aluminum compound, and a spheroidal magnesium chloride support.