Planetary Technologies, Inc. is developing technologies that process various source materials for the end goal of carbon dioxide removal through ocean alkalinity enhancement (OAE). One such technology that has been developed processes asbestos tailings with sulphuric acid solution, recovering magnesium as well as nickel and cobalt in the leach liquor. Leaching was conducted in 3 m and 5.5 m height columns with varying lixiviant flowrates (derived from the irrigation rates) to study heap leaching efficiencies after 100 days. Two more columns of 3 m were loaded with feed, and a load of 300 kg applied to the top of the heap to simulate leaching at 9 m height to observe if this affected physical and/or chemical performance of the leach. Two different flowrates were studied, and these tests yielded higher metal extractions. The optimized leaching efficiencies were 93%, 92%, and 89% for Mg, Ni, and Co, respectively. Furthermore, the 25% asbestos content of the feed was reduced to non-detectable in the leach residue. The resulting pregnant leach solution was collected and contacted with fresh feed to consume the excess acidity. The pH-adjusted discharge solution was treated with reagents to precipitate Fe, Al, and other impurities before a high-grade mixed hydroxide precipitate of up to 30.5% Ni was produced in a two-stage counter-current precipitation sequence.