Corrosion in mining: Technical solutions for operational integrity

Corrosion in mining constitutes a highly complex technical problem due to the simultaneous interaction of multiple degradation mechanisms in extremely aggressive environments. Unlike other industrial sectors, the mining industry exposes its assets to conditions where fluids with high solid loads coexist, severe pH variations occur, reactive chemical species are present, and hydrodynamic conditions favor the removal of protective films. This scenario turns corrosion into an accelerated, nonlinear phenomenon that is highly dependent on operational variables.

One of the most critical aspects is observed in hydraulic transport systems, particularly in slurry pipelines, where the material is continuously subjected to the combined action of abrasion, chemical attack, and electrochemical processes. In these systems, degradation cannot be analyzed from a single perspective, as the synergy between mechanisms generates material loss rates significantly higher than those expected from corrosion or wear individually.

Types of corrosion in mining operations

In mining operations, corrosion mechanisms develop under conditions that favor both direct chemical reactions and coupled electrochemical processes. Chemical attack is particularly relevant in environments where acidic or alkaline solutions predominate, such as leaching processes or in the presence of acid drainage. In these cases, metal dissolution occurs through direct reaction with the medium, without the need to establish clearly defined electrochemical cells, which can generate uniform or localized attacks depending on material heterogeneity.

However, in most aqueous systems in the mining industry, the dominant mechanism is the electrochemical process, in which anodic and cathodic zones are established on the metal surface. The presence of dissolved oxygen, concentration gradients, and microstructural differences favor the formation of microcells that accelerate metal dissolution. This phenomenon intensifies under turbulent flow conditions, where constant renewal of the electrolyte removes corrosion products and keeps the metal surface active.

Abrasion introduces a critical mechanical component into this system. Solid particles suspended in the fluid impact and slide over the internal surface of equipment, removing passive layers or protective coatings. This effect not only increases the wear rate but also continuously exposes fresh material to the corrosive medium, intensifying the kinetics of the electrochemical process. Consequently, the interaction between abrasion and corrosion generates a synergistic mechanism known as erosion-corrosion, which dominates many mining applications.

The following video explains how to control corrosion in the mining industry. Source: PAXCON Coatings.

Systems affected by corrosion in mining

The most critical areas from a corrosion standpoint in the mining industry are characterized by operational conditions that favor the simultaneous activation of multiple mechanisms. Slurry pipelines represent one of the most challenging examples, as they operate under multiphase flow with high solid concentrations. In these conditions, velocity distribution, system geometry, and particle nature directly influence wear and corrosion patterns.

In elbows, valves, and section changes, turbulence increases, generating preferential impact zones where abrasion is more severe. These regions often coincide with areas of higher electrochemical activity due to the constant removal of protective films, resulting in accelerated localized degradation.

Storage tanks and processing equipment also present significant challenges, especially when containing chemically aggressive solutions. Fluid stratification, liquid-gas interfaces, and temperature variations can create electrochemical gradients that favor localized corrosion.

In systems associated with acid drainage, conditions are even more severe. The combination of low pH, high sulfate concentration, and the presence of dissolved metals creates a highly conductive and chemically active environment, where the corrosion rate can increase exponentially.

Critical mechanisms: erosion-corrosion and AMD

From an engineering perspective, erosion-corrosion is one of the most complex and destructive mechanisms in mining. This process cannot be considered a simple sum of wear and corrosion, but as a synergistic interaction where mechanical action modifies the electrochemical conditions of the system. The removal of passive layers reduces corrosion resistance, while corrosion weakens the surface, facilitating its removal by abrasion.

Acid mine drainage (AMD) introduces an additional highly aggressive degradation mechanism. This phenomenon originates from the oxidation of sulfide minerals, generating sulfuric acid and releasing metal ions into the medium. From an electrochemical perspective, AMD increases electrolyte conductivity and lowers pH, conditions that favor anodic reaction kinetics. Additionally, the presence of acidophilic bacteria can catalyze these reactions, further intensifying the process.

The combination of erosion-corrosion and AMD represents a critical scenario where conventional materials fail rapidly if adequate protection strategies are not implemented.

Causes of corrosion in mining

The causes of corrosion in mining in mining environments are associated with the interaction of physicochemical and operational variables. The presence of water acts as an essential electrolyte medium for the development of electrochemical reactions, while dissolved oxygen functions as an oxidizing agent in most systems. The chemical composition of the fluid, particularly the presence of chlorides, sulfates, and acidic species, determines the aggressiveness of the environment.

Hydrodynamic conditions also play a fundamental role. High flow velocities can increase mass transfer, favoring electrochemical reactions, but simultaneously intensify abrasion. Likewise, interactions between dissimilar materials can generate galvanic pairs that accelerate the degradation of the less noble metal.

Impact of corrosion on the mining industry

Corrosion in mining is one of the most underestimated and least understood challenges in industrial operations. Mining equipment and infrastructure are exposed to extreme environments where minerals, water, chemicals, and salts combine to accelerate metal degradation, tis generates high maintenance costs, unplanned downtime, and reduced operational efficiency.

All mining operations, from underground mines to surface facilities, must consider corrosion as a critical factor affecting equipment lifespan, safety, and profitability. Effective corrosion management ensures the durability of infrastructure, vehicles, and machinery, protecting production and operational integrity.

Corrosion in slurry pipelines

Transporting iron ore concentrate via slurry pipelines offers several advantages over rail or road transport, including lower accident rates, lower energy consumption, higher reliability, cost savings, and lower environmental impact. However, corrosion in mining plays a critical role, as pipeline roughness directly affects transport capacity. During transport from beneficiation to filtration and pelletizing, metal surfaces are exposed to corrosive aqueous media, representing approximately 90% of all metal corrosion failures.

Slurry transport systems include storage tanks, centrifugal pumps, intermediate storage, pipelines, and control systems. High turbulence, particle impact, and vibration can remove protective oxide layers, increasing corrosion rates. Therefore, pipeline design must consider these factors to prolong service life and maintain operational reliability.

Table 1. Representative slurry pipeline systems worldwide

Project / Location	Status	Transport Capacity	Corrosion Control Measures
Iron ore, Australia	Operational	10,000 t/day	Coatings, cathodic protection
Copper concentrate, Chile	Feasibility	15,000 t/day	Alloys, monitoring
Nickel slurry, Canada	Engineering	5,000 t/day	PU linings, flow optimization

Technical solutions for operational integrity

Effective control of corrosion in mining requires a comprehensive approach based on understanding the mechanisms involved. Material selection must consider not only corrosion resistance but also behavior against abrasion. In many cases, the use of composite materials or specialized internal linings yields better results than traditional metals.

Coatings play a key role as a protective barrier. However, their performance depends on factors such as adhesion, impact resistance, and chemical compatibility with the medium. In severe environments, coatings must be designed to withstand both chemical attack and mechanical action from particles.

Controlling operational variables, such as flow velocity and solid concentration, reduces the severity of erosion-corrosion. Additionally, the implementation of online monitoring systems facilitates early fault detection, enabling predictive asset integrity management.

Corrosion in mining is a natural process, and even resistant equipment can deteriorate without preventive measures. Cathodic protection using sacrificial anodes of magnesium, zinc, or aluminum can significantly extend equipment life. It is crucial to monitor and replace these anodes before they are fully corroded. Corrosion control strategies adapt to the environmental conditions of each industry, including mining, marine, aerospace, and automotive.

Main protection methods include

Material selection

Materials must combine high mechanical strength, corrosion resistance, and cost efficiency. For example, wire meshes in wet screens can be replaced with PU panels, reducing corrosion. Proper material selection ensures greater durability, lower maintenance, and sustained operational efficiency.

Surface coatings

Protective coatings, whether more noble or less noble than the base metal, act as a barrier against corrosion. For example, steel structures can be coated with copper (more noble) or zinc (less noble). Coatings must be free of pores or cracks to prevent galvanic cells that accelerate metal degradation.

Use of corrosion inhibitors

Inhibitors are substances added in small concentrations (~0.1%) to slow electrochemical reactions on metal surfaces. They can be anodic, cathodic, or organic adsorption inhibitors, effectively reducing corrosion in aggressive mining environments.

Proper equipment design

Equipment design is essential to mitigate corrosion in mining. Avoiding contact between dissimilar metals in the presence of electrolytes, minimizing vibrations, ensuring adequate drainage, and post-weld heat treatment in heat-affected zones are essential practices. High turbulence and vibration can accelerate corrosion and fatigue in slurry pipelines, vibrating screens, and crushers, so these systems require regular monitoring and maintenance. Drying equipment after cleaning and designing tanks for complete drainage reduces crevice corrosion, while managing residual stresses prevents stress corrosion cracking.

Conclusions

In the mining industry, corrosion in mining does not occur in isolation. The combination of chemical attack, electrochemical processes, and mechanical abrasion generates erosion-corrosion, where the constant removal of passive layers exposes fresh metal and accelerates degradation. This phenomenon is critical in elbows, valves, and section changes, where turbulence and solid particle impacts intensify localized corrosion, quickly compromising equipment lifespan. Understanding these mechanisms is essential to design effective mitigation strategies and ensure operational continuity.

The severity of corrosion in mining depends on multiple factors, including pH, chloride and sulfate concentrations, dissolved oxygen, and fluid stratification. High flow rates and solid concentrations increase both abrasion and erosion-corrosion. In acid mine drainage (AMD) systems, low acidity and high conductivity favor rapid electrochemical reactions, while acidophilic bacteria can catalyze these processes. These extreme conditions make corrosion a constant risk, raising maintenance costs and the likelihood of unplanned downtime.

Effective control of corrosion in mining requires a comprehensive approach combining resistant materials, specialized internal linings, inhibitors, and proper equipment design. Adjustments to flow velocity, solids handling, and system geometry help reduce erosion-corrosion, while predictive monitoring systems and cathodic protection facilitate early fault detection. This combination of strategies optimizes maintenance planning, prolongs critical infrastructure life, improves safety, and ensures operational reliability in aggressive mining environments.

References

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4. Chambers, A. J., Sunderman, C. B., Benton, D. J., Brennan, J. T., & Orr, D. T. (n.d.). Evaluation and mapping of corrosion in western USA underground metal mines. Eighth International Conference on Deep and High Stress Mining.
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