Gamsberg Mine's Sustainable Water Solutions

Kennedy Sithole, Projects and Export Manager for Saint-Gobain PAM, Southern Africa region, takes us through Saint-Gobain PAM first mine project in South Africa from the Oranger River to the Gamsberg mine in Northern Cape province. 

The purpose of the pipeline is to supply raw water to the mine, primarily to be used for construction purposes, and the running of the mine operations. While the anticipated lifespan of the mine is 40 years, the Saint-Gobain PAM pipes will outlast this period, even in the extreme desert temperatures. 

Gamsberg is part of the Black Mountain Mining (BMM) operations and is located about 30km from BMM’s base at Aggeneys, in South Africa’s Northern Cape province. Gamsberg will exploit one of the largest known, undeveloped zinc orebodies in the world and will comprise an open pit mine and a dedicated processing plant. 

Kennedy Sithole explains the scope of work undertaken by Saint-Gobain PAM, “In the submission of our bid tender, we had to supply 29.5 kilometres of 500mm diameter ductile pipe, installed to run from the Orange River to Gamsberg. I was the Saint-Gobain project sales manager on that project.” Sithole describes the tender process for which Saint-Gobain PAM was awarded the project: “The mine owner issued a tender to EPC contractor who then awarded Saint-Gobain PAM a tender for the supply of the ductile iron pipes in March 2017. A local consulting engineers firm were appointed to manage the project,” he explains.

The Saint-Gobain PAM pipes are manufactured according to a centrifugation process that consists in applying a layer of liquid cast iron in the cylindrical shell rotating at high speed and solidifying the metal by continuously cooling the shell.

The cost of pumping and water losses during the life of a network are considerably greater than the cost of the initial purchase, the economic selling strategy applied the use of TCO which represents all the expenses incurred by the pipe owner during the lifetime of the pipeline and it is calculated according to ISO 15686-5.

The Saint-Gobain PAM TCO calculator is designed to assess costs (acquisition, installation and operation) of different types of material (steel, HDPE, PVC and ductile iron) over a specified timeline.                                               

This particular pipeline comprises of :

• 2 100m of Class 50 bars,
• 7 600m of Class 40 bars
• 19 800m of Class 30 bars,

to be installed above ground resting on concrete pedestals. This makes it easier to maintain as there will be no need to dig up the pipe if repairs are required - in the unlikely event of leakages. After the completion of the project, the mine is responsible for the maintenance of the pipeline. 

The cast iron is a sturdy material, which withstands high service pressures and external mechanical accidents.

The expert describes that Saint-Gobain PAM has numerous manufacturing facilities, including European union, China and Brazil. The high-pressure Hydroclass pipe was manufactured in the Chinese manufacturing plant, complying to the pressure class according to EN 545 and ISO 2531. 

 “We had a third-party inspection to confirm the quality and conformity of the pipe to the international standard,” Sithole assures.

The installation was started around August 2017 and the testing of the pipe was completed within the first week of April 2018.    

“As the water flow rate will be dependent on how the mine pumps the water, the water pressure varies. Over the length of the pipeline, there are three sections. One is a 50-bar pipe, the second is 40-bar and the third is 30-bar, depending on the distance from the mine. This is a key point,” Sithole stresses and adds, “The 50-bar pipe is a special material that can withstand such high pressure.” Kennedy Sithole

The project took place in a desert like region of South Africa, where extreme temperatures are common. The pipes supplied will withstand the heat. Sithole adds that “desert or forest, the products, the external protection and pipe assembly are designed for a large variety of climates and situations. We had to have the high pressure pipes and related fittings especially made.”

“In addition, because the pedestals that hold the pipe above the ground were already erected to receive the pipes, we had to ensure that the pipes were supplied to the correct length – the span between pedestals.”

The pipe comes in six metre lengths, but even in the EN 545 specification, the pipe can be slightly shorter or longer, he explains, “To accommodate the required overlap section, the contractor had to cut the pipes in some instances.”

While this may sound like a small job, the reality is that there were almost 5 000 pipe sections for the project.

Sithole continues, “On the project there were three main companies, the pipe installer, the engineers and Saint-Gobain PAM. With three companies working on that project, we developed a really good working relationship; with collaboration from all parties, working on problems together and finding solutions together.” He further explains that Saint-Gobain PAM’s relationship with its clients is based on a true partnership. 

The manager goes on to explain the logistical challenge that the project encountered: “You must realise, that to deliver the pipes and fittings to the mine in the desert from Cape Town port, took over 270 trucks. This exercise is what bagged us the project,” Kennedy Sithole concludes with a grin

Hydroclass pipe range

The ductile iron pipes are socket and spigot pipes, manufactured by a centrifugal process in accordance with Standards: ISO 2531-2009 and EN 545-2010.

External coating is 200g/m² metallic zinc with synthetic coating

Internal lining: Blast furnace slag cement (BFSC) mortar lining

Standard joint in EPDM for the pipes and Tyton gaskets for the fittings. The gaskets are manufactured in EPDM elastomer suitable for potable water in accordance with ISO 4633-2002 and EN 681-1.

The fittings are internally lined by a fusion bonded epoxy, with a minimum average thickness of 250 microns according to EN 14901:2006.