The Selection and Sizing of Tracts Comprisinq a Manganese Nodule Ore Body

Abstract

ABSTRACT Areal requirements of ocean mine sites, required to meet economic objectives and based upon present technology are large when compared with land mines and with earlier estimates. In support of this conclusion, information on Pacific Ocean nodule ore bodies suitable for long range commercial mining is presented. Approaches to the technical and economic evaluation of an ocean deposit as well as land mine evaluation techniques and procedures are discussed. The differences between land and ocean mining and exploration are stated and basic similarities are brought into focus. Mine prospect evaluation criteria such as reserves and mine life, ore cut-off grade, production rate are reviewed. Details of the technical factors which must be considered in determining the size of a mine such as; bathymetry, population and concentration, assay, mining equipment limitations, and marine ecology are assessed. A formulation for the determination of required tract size to satisfy production needs is presented. The formulation includes parameters such as ore concentration, ore grade, presence of unmemorable areas, dredge device efficiency, and mining effectiveness and sweep efficiency. 1. INTRODUCTION The primary objective of this paper is to provide sufficiently detailed information concerning actual Pacific Ocean potential nodule mine sites to permit assessment of the realism and viability of ore bodies for long range commercial mining. The information presented has been kept at a "representative" rather than "exhaustive" level to minimize exposure of proprietary information. All data readily available and in the literature is essentially prospecting or reconnaissance type information. That is, the information is acquired over very large expanses with the objective of locating occurrences of possible commercial interest. Once an area of interest is identified, then the second key phase, exploration, commences. Exploration involves further research which includes preliminary surveys over relatively restricted areas to delineate the extent, concentration, and grade of occurrences of interest identified by prospecting and to establish areas as candidate mine sites. For this phase of surveying, large amounts of detailed information depicting deposits are gathered. This can take the form of closely spaced TV survey tracks, still camera bottom photographs, preliminary bathymetry, nodule sample collection and analysis, and the acquisition of general physical oceanographic data. Reference {I} provides additional detailed descriptions of the efforts and objectives of this phase of a nodule survey program and also includes information on the following even more detailed survey efforts required to develop a mine site. 2. OVERALL ECONOMIC & TECHNICAL CONSIDERATIONS Comparisons To Land Exploration And Mining Whether it be land or ocean mining, the connotation of "ore body" is an economic one. Mineralizations do not become "ore bodies" without meeting criteria dealing with market requirements and mine development, mining, and processing costs. The evaluations that convert a-mineral occurrence to " ore" is one which progresses from "probable" ore -- a low probability prospect to " proven" ore -- a highly probable tract of mine site. Land and ocean mining alike follow well established practices, all working toward increasing the probability that the identified potential ore occurrence will become an ore body.