The circular economy mandates the processing of waste from metallurgical and mining operations, an endeavor fraught with social, technical, and economic challenges. Frequently, there are large amounts of these materials, which have limited value and contain nuisance elements that must be removed and sequestered to produce a viable product. Time-consuming research, development, and engineering are required to create and prove new processes. The Inco Iron Ore Recovery Plant operated from the mid-1950s to 1983. It was a “circular economy” operation, which recovered all values contained in the pyrrhotite feed to produce marketable nickel oxide, iron ore, sulfuric acid, and steam. The development process identified suitable equipment and process conditions for (a) high-temperature roasting/selective reduction of pyrrhotite, (b) selective ammonia leaching, reagent and nickel recovery, and (c) agglomeration and induration of fine iron oxide. Technology development lasted 8 years, 1947–1955. The development process employed by Inco, a technology leader of the time, involved the same procedures we use today—paper and laboratory studies, extensive piloting, and semi-commercial testing with external partners—but in a more favorable social, economic, and business environment. Based on a contemporary account, this chapter describes the development process and technical hurdles overcome to create the iron ore recovery plant and compares what would be encountered today when entrepreneurs, designers, and engineers face significantly greater business, environmental, and social hurdles. International Energy Agency targets mandate increasing reprocessing and recycling, i.e., reach a circular economy. We must take actions to accelerate the development process while maintaining guardrails against wasteful and harmful projects.