N. Verbaan
SGS Canada,
Canada
Keywords: critical minerals, ramp-up, hydrometallurgy
Summary:
In 1998, Terry McNulty presented an SME paper that surveyed 41 processing plant case histories and identified the dominant causes of success and failure. That survey resulted in creation of four curves, graphically portraying the approximate rates of achievement of design capacity over time for projects that ranged from very successful to marginal to unsuccessful. Identifiable characteristics (such as: maturity of technology, level of understanding or characterization of feed material and the degree of pilot plant test campaigns) of those projects were tabulated. Updated presentations were given at SME 2004 (Denver), at COM 2014 (Vancouver) and at COM 2024 (Halifax). These so-called “McNulty Curves” have been widely adopted by operating companies and project financing firms for use as a checklist for risk assessment. Many of the McNulty curves presented to date have been based on traditional commodities. Industry electrification, climate change technologies as well as the current trend to develop domestic supply chains for non-traditional or critical commodities (such as rare earths, graphite, lithium, nickel, cobalt, gallium, germanium, and antimony) have led to new critical mineral projects being developed. While traditional commodity projects can bench mark against existing projects to assist in de-risking and generating capital and operating cost estimates, this is more difficult for critical mineral projects. Without bench marking, additional engineering studies supported by pilot and/or demonstration plant operations may be required. This presentation will highlight several McNulty Ramp-up Curves of current critical mineral projects using production data out of the public domain, and contrast these with predictions made in prefeasibility and feasibility studies.