ABSTRACT:

The present paper describes the experimental investigation of model coarse-grained slurry on a re-circulation pipe loop with smooth stainless steel pipes. Graded pebble gravel and glass balls were used as a model for poly-metallic nodules, and very fine glass beads as a model for fine-grained sand. The investigation was focused on evaluating the effect of slurry velocity and particle concentration on pressure drops and the slurry flow behavior in the turbulent regime. Also the effect of fine-grained particle addition on slurry behavior is described.

INTRODUCTION

The poly-metallic nodules at the ocean bottom contain a number of metals therefore their exploitation and subsequent processing will be occurring in the near future. The mining of poly-metallic nodules from the ocean bottom consists mainly of the following parts, in particular, nodule exploitation and collection at the ocean bottom, nodule handling at the bottom and vertical transport to the surface, and solids separation at sea surface. The most suitable method for nodule transport to sea surface seems to be hydraulic pipelining. For this reason, it is suitable to deal with a method of nodule handling and transportation in more detail. Transport of nodule-water mixture in vertical, inclined or in horizontal pipes will play a significant role in the deep sea mining technology. The nodules will be exploited at the sea bottom together with fine-grained sand or clay and transported hydraulically to surface as coarse-grained heterogeneous slurry. The raw nodule-water mixture will consist of nodules as well as sand and clay particles collected together with the nodules. Advanced knowledge of the flow behavior coarse-grained and complex slurries is therefore important for the safe, reliable and economical design and operation of pipeline technology. The preferred predictive tools are models based on the physical description of slurry flow behavior in a pipeline (Matousek, 2005).

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