In 2014 a leading diversified natural resources company was considering the development of its bauxite deposit in Guinea, Africa.
The project which comprises a mine and associated infrastructure would produce and export 10 Mt/y of bauxite.
The company had previously completed study work on the project which considered conventional road and/or rail options as the means of delivering the product to the available port facility.
Ausenco was commissioned to conduct a concept study that considered an alternative approach to the transportation of the product to the port facility using a long-distance slurry pipeline, and to compare this approach with a more traditional rail transport method.
Ausenco developed a conceptual study and order of magnitude cost estimate to evaluate the technical and commercial feasibility for the proposed plant-to-ship concept, including the necessary infrastructure upstream and downstream of the long distance pipeline, the process plan and terminal/port facilities. From the bauxite process plant, the bauxite pipeline would transport the concentrate to the terminal and river port facilities located approximately 110 km away.
The pipeline system would comprise a buried 26-inch API5L-X42 bare steel pipe with a single pump station located near the process plant. The pipeline, including two intermediate valve stations, would be operated from the process plant main control room via a fibre optic communication system along the entire length of the pipeline.
At the pipeline terminal, the bauxite concentrate reports to de-sliming cyclones where approximately 4.6 Mt/y of fines (slimes) are separated and rejected to the tailings storage facility. The de-slimed concentrate reports to a bank of three belt filters and is dewatered to a moisture limit suitable for safe shipping.
The scope of work included the following key elements for the slurry pipeline transport option:
- Design of a bauxite processing plant to provide a suitable product for transportation in the pipeline;
- Design of a long-distance slurry pipeline &including head pump station, intermediate stations and terminal station; and
- Dewatering facilities and associated material handling infrastructure to support the barge operation.
A holistic approach for cost-effective processing
The cost-effective processing, transport and shipping of fine bauxite using a long-distance slurry pipeline transport infrastructure would be a world first. Challenges associated with dewatering/drying fines and achieving a cost effective solution required a holistic plant-to-ship supply chain approach.
The proposed concept plant-to-ship infrastructure is deemed technically feasible. Value to the project and enhancement of capital and operation cost confidence level can be achieved from progressing engineering definition in the following areas:
- Advance bauxite test program to optimise ROM upgrade and de-sliming requirements;
- Field pipeline route assessment and constructability review;
- Stockpile simulation (supply chain simulation) and optimisation of stockyard/footprint for terminal station;
- Validate geotechnical assumptions for process plant/terminal station;
- Bauxite rheology testwork, define particle degradation potential, and corrosion test work for pipeline material selection; and
- Progress study and cost estimate to Definitive Feasibility Study.
The client is currently comparing the technical and commercial feasibility options available before determining the next steps.