Company: Iron Ore Producer
Corrosion Control in Iron Ore Slurry Pipelines
Wastewater treatment is essential to preserve public health and environmental balance. Wastewater originates from domestic, industrial, and commercial uses, containing organic and inorganic matter, pathogenic microorganisms, nutrients, and toxic compounds. Its accumulation can cause unpleasant odors, pollution, and health risks, making proper collection, treatment, and disposal essential.
Treatment processes are divided into physical, chemical, and biological operations, grouped into three stages: primary, secondary, and tertiary.
- Primary treatment removes settleable solids through screening and sedimentation.
- Secondary treatment reduces organic matter through biological processes such as activated sludge systems or aerated lagoons.
- Tertiary (advanced) treatment removes nutrients, toxic compounds, and dissolved solids through filtration, adsorption, or chemical precipitation.
Wastewater’s physical characteristics include total solids, odor, temperature, color, and turbidity; chemical characteristics include organic and inorganic compounds and gases; and biological characteristics involve microorganisms—some pathogenic, others beneficial for treatment. The Biochemical Oxygen Demand (BOD) is a key parameter to measure organic pollution and to design treatment plants effectively.
Biological processes can be aerobic, anaerobic, or anoxic, allowing the removal of organic matter and nutrients such as nitrogen and phosphorus. Advanced treatments, such as filtration and adsorption, further improve water quality for reuse in irrigation, industry, or aquifer recharge.
Finally, the resulting sludge must be properly managed to avoid environmental impacts. Overall, wastewater treatment is a key tool to ensure water availability and quality, contributing to environmental sustainability.
Problem: Leakage Due to Corrosion in the Transport System
One of the main challenges faced by the company was internal corrosion in the slurry pipeline, caused by dissolved oxygen in the pumping system. This issue led to up to 60 leaks per month along the 27 km pipeline, disrupting operations and generating significant economic losses due to the leakage of concentrated mineral slurry.
Objective of the Sulfite Treatment
The technical objective of the treatment was to control the level of dissolved oxygen by dosing a corrosion inhibitor, targeting the following parameters:
- 15 ppm residual at the pipeline inlet
- 5 ppm minimum residual at the pipeline outlet
Results Achieved
After implementing the treatment, the following results were obtained:
- 15 ppm residual at the inlet
- 10 ppm residual at the outlet
Although the residual concentration was slightly higher than expected, the results showed a significant improvement in internal corrosion control, resulting in a substantial reduction in leaks across the pipeline.
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