Pipes with added protection

Jon Lawson

Jorge Solorio details a solution for mineral processing plants when transporting aggressive chemicals

Mineral processing is extremely demanding on piping infrastructure. The challenge of maintaining long-term reliability is considerable and these difficulties are expected to increase. Existing pits and mine sites are now frequently extracting ores of lower concentration from deeper in the earth’s crust, causing a shift in the chemistry of processed ores. Whether leaching precious materials from the ground or processing raw materials after excavation, the highly corrosive chemicals typically used throughout various mining operations can cause ongoing maintenance challenges and costly, premature failures for metallic piping systems. Chemicals that are commonly used in various mining operations - often at high temperatures, can wreak havoc on the integrity of most piping systems.

By resisting corrosion, sedimentation and crystallisation that compromise metallic systems, Corzan CPVC can prove advantageous for a variety of mineral processing applications, including electrolysis operations, electrowinning, electrorefining, acid service lines, tailings lines, gas vent scrubbers, froth flotation operations and wastewater treatment. This translates to lower life-cycle costs, as well as the reduction of maintenance time and corrosion monitoring. Coupled with the benefits that CPVC can offer through its simplified solvent welding installation process and stable pricing, replacing a metallic system with this alternative solution can be beneficial.

Corrosion resistant

Corzan CPVC is an engineered thermoplastic produced by the chlorination of polyvinyl chloride resin. It offers impressive resistance due to its mechanical strength, which allows it to be corrosion resistant and withstand high temperature applications, thereby increasing the life of the system. Unlike metal industrial piping systems, this type of pipe will never pit or scale since it doesn’t react to most mineral acids, bases, salts and aliphatic hydrocarbons.

A key advantage that Corzan CPVC pipe has over metallic pipe is a smooth inner surface, which is resistant to scaling and fouling. This means that friction pressure losses in the fluid flow are minimised from the beginning and do not significantly increase as the system ages, as can be the case with metal pipes subject to scaling.  The flow rate remains consistent throughout the life of system and is never compromised by pitting or scaling. This not only improves productivity and limits downtime over the years but, in some cases, it means that a considerable cost savings may be realized through the ability to actually downsize the piping system at the outset. And, with a smaller pipe comes increased energy savings, as less energy is required to move the fluid through the pipe. Corzan piping systems have a smooth inner surface and resists scaling and fouling, which minimises friction pressure losses in the fluid flow, resulting in optimum flow rates.

At high temperatures, Corzan CPVC remains mechanically strong. One can expect the pressure-bearing capabilities will last for 50 years or more, providing long lasting performance and will reduce costs to facilities.

The piping is lightweight and only requires simple tools for installation, and maintenance is less complex - which reduces labour time. When properly installed, a solvent-welded Corzan joint becomes the strongest part of the entire piping system.

Its maker says that this piping is safer to operate than metal systems as its thermal conductivity is lower. This not only reduces heat loss, but also keeps the overall surface temperature of the pipe lower, reducing the chance of burns to maintenance and operating personnel and minimises its contribution to the overall ambient temperature in the area of operation.

The piping has a high flammability resistance as its limiting oxygen index is 60. It requires 60% of oxygen to be able to sustain a flame when burning. As our atmosphere only consists of 20 to 21% of oxygen, CPVC will not burn on its own and will not contribute to flashover. When tested according to EN 13501-1:2002 to determine its fire classification, CPVC achieves a rating of B-s1-d0 (low flammability, no smoke development, no burning drops).

Corzan Industrial Systems and its customers have tested hundreds of different chemicals to determine the system’s chemical resistance. These industrial piping systems have a field-proven record that meets the ever-increasing demands of mineral processing applications. By utilising high-performance, corrosion resistant Corzan CPVC resin-based cement with the piping systems, critical demands are achieved. This combination of materials provides an excellent balance of properties that improve reliability and user confidence. It also reduces capital and life-cycle costs, avoiding costly downtime and most importantly, allowing mineral processing plants to remain operational and optimally productive.

For more information, visit www.engineerlive.com/ime

Jorge Solorio is with Lubrizol Advanced Materials.

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