ABSTRACT

Assessment was performed on the use of polymer-based materials or liners for large solids particle slurry applications. The study was conducted in a pilot-scale horizontal slurry flow loop using two different solids: sand and rocks. Each of the respective slurries from these particles contains some amount of the other. For sand slurries, sand-to-rock ratio was about 3.6 whereas for rock slurry has 0.1. The sand had median size, d50 of 0.240 mm (0.009 inches) and the rocks size was --2 mm (2 inches). The study was done in a 193.7 mm (7.625 inches) pipe flow loop with mixture velocity and solids concentration of 7.0 m/s (23 ft/s) and 15.2-21.9% v/v, respectively. Two polyurethane (water presoaked and unsoaked), 2 neoprene materials, 1 high density crosslinked polyethylene and carbon steel were subjected to these slurries. In general, the presence of the large solids significantly affected the wear based on mass loss percentage. Wear increases significantly from sand to rock slurries for polymeric materials whereas the converse was true for the carbon steel. In slurries where erosion rate is faster than water absorption rate, the advantage of water absorption for polyurethane should be evaluated. Although, direct comparison among polymers was not done, it was observed that each material responded differently to large solids. Neoprene performance is manufacturer specific and evaluation method or technique should be designed carefully, specifically slurry composition.

INTRODUCTION

Slurry pipeline systems are used for the extraction of bitumen from mined ore in the oil sands industry in Alberta, Canada. Not surprisingly, because of its relatively low cost, carbon steel is the default material for slurry pipelines in this industry. However, the handling and processing of slurry results in significant pipe wall material losses or wear. These losses are attributed to the combined effects of erosion and corrosion due to the exposure of pipe wall materials to an aerated mixture of solids (mostly silica), bitumen and water. In an attempt to mitigate this issue, mined oil sands operators have adopted polymer based pipe liners (neoprene and polyurethane) as one of the strategies. While success has been achieved in some of the slurry applications, for some systems, their wear rates are either similar or worse than carbon steel. There are ongoing research works to understand the reason(s) behind their mixed wear resistance performance. In other mining or hardrock mining and dredging operations, usually polymer liners such as natural rubber, high density polyethylene and high density crosslinked polyethylene are used. Experience and discussion with industry indicates that, on average these liners tend to provide total ownership cost-savings over unlined carbon steel.

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