A Model for Relative Ranking of Blocks and Selection of Candidate Mine-Sites for Manganese Nodule Mining: A Case Study of the Indian Ocean
Authors: Garnett M. , Kodagaii V.N. , Sankar S. Jai 
Published: October 2008

Recovery performance may be measured in absolute terms or invrelative ones which relate the mining outcome to the expected. Consideration is possible in terms of the control exercised by the operator. Eventual mineral output is the only figure of complete certainty. The paradox is that while performance is judged against the sampling the reverse also applies. The R/E factor and its four component factors are the best overall measures of performance. Choice of equipment for sampling and mining is very important. The sampling process may introduce errors and the sample density may lead to poor mining block selection. The resulting recovery performance, is most visible on a regression curve. Changes in the cutoff grade must also be taken into account to avoid unrealistic production targets.

Estimation methods incorporating different mathematical assumptions and techniques may cause over- or under-estimation of the grade and volume. If the selective ability of the mining equipment does not match the size of the blocks the performance will be compromised. The treatment plant efficiency, throughput rate, and degree of bedrock clean-up also affect performance. Maximization of throughput does not yield the optimum results. Marine conditions, outside the operator's control, affect not only operational availability but also performance.

Examples are provided from actual operations for various commodities, showing the relative magnitude of the different effects upon performance,

Introduction

Performance is the act of execution or accomplishment of a task, usually with regard to effectiveness in overcoming obstacles. Itsuggests the conquering of difficulties and emphasizes what has been done under test conditions to achieve a result. The above key words are very pertinent to marine mining.

The marine mining operations under consideration are those engaged in the exploitation of continental shelf deposits of tin, precious metals (gold and platinum), and diamonds. Performance monitoring in the industry is undertaken by means of a variety of achievement measurements. These are recorded or determined, and then analysed on a regular basis.

Short and long-term operational performance may be examined in terms of either how it is measured or what affects it, adversely or otherwise. The results may be measured in either absolute or relative terms. The absolute include those parameters which may be measured directly, either easily or with some difficulty. The relative measurements involve a comparison with what was expected on the basis of a mining plan or feasibilitystudy.

The multi-phase process leading to successful production starts with sampling, usually by some form of drilling. Estimation of the grade of each sample follows, and its accuracy is affected by the size of the samples, the sample density, and the mathematical procedure used 1.A cut-off grade is employed to exclude unpayable ground. Mining blocks, each encompassing a minimum number of samples, are selected as part of the total reserve estimation prwedure.

A proposed mining system maybe tested, perhaps as part of a bulk sampling program, before full scale production commences.