Estimating the metal content of SMS deposits

A growing database of global SMS occurrences is beginning to provide clues to the likely distribution, size and grade of the deposits. The need for such an assessment is becoming more urgent, as a number of leading companies and international consortia have begun to invest in intensive exploration campaigns for SMS, and governments and other organizations have begun to establish the legal framework for seafloor exploration and exploitation of minerals in territorial and international waters [1]. Various models for multi-year exploitation of SMS deposits have been proposed, although production rates and other technical aspects have not been fully tested or disclosed. These models are based on comparisons with mining on land, which is reasonable, as it must be assumed that any seabed mining would have to compete economically with operations on land. In particular, comparisons with grades and tonnages of land-based deposits can be used to quickly identify those SMS occurrences that are likely to be uneconomic. However, questions about the numbers and sizes of SMS deposits continue to be raised. Using the general principle that the frequency distributions of deposit sizes and grades in well-explored areas of the seafloor can serve as models for tonnages and grades of undiscovered deposits, many of these questions can now be addressed, allowing deposit occurrence information to be translated into more meaningful assessments of the global “resource” potential.