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Mining explosives maker hires Johnson Controls to help solve logistical challenges

28th February 2014

By: Zandile Mavuso

Creamer Media Senior Deputy Editor: Features

  

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Mining explosives supplier AEL Mining Services (AEL) has approached Johnson Controls to assist in resolving AEL’s logistical challenges in supplying ammonia – which is a key ingredient in the manufacturing of explosives for the mining sector.

AEL is facing seasonal constraints in the supply of ammonia and, with Johnson Controls’ assistance, the company hopes that it will resolve these challenges and secure a sufficient supply to keep its local plants functioning at capacity during peak season when ammonia is in high demand.

“To avoid downtime at our manufacturing plants, AEL has to negotiate three block train deliveries of ammonia each week with State-owned rail transport company Transnet Freight Rail. To make this service model work, we need to offload all the rail cars during a 24-hour window period, moving the ammonia from the high-pressure train bullets to AEL’s low-pressure 16 000 t capacity bulk-storage tank,” says AEL senior project manager Robert Burnie.

To do this, AEL is upgrading its offloading facilities in Modderfontein, Johannesburg, at an estimated cost of about R60-million. Two Johnson Controls Frick RWF II 1080 ammonia screw compressor sets – the first of these high-capacity compressors of its kind – are pivotal to the success of the solution, he notes.

As part of the upgrade, the new weighbridge was completed in mid-August last year and the refitting of the rail siding for jumbo rail cars is scheduled for completion by the end of next month.

Johnson Controls operations manager Russell Hattingh notes that AEL selected the two screw compressors, with a 1 300 kW motor each to help them meet their requirements. This is the highest capacity model in the Frick compressor range and the biggest of its kind in South Africa. Combined, these compressors can move 198 kg/min of ammonia – equivalent to refrigeration duty of 1 850 kWR at –33 °C.
Burnie mentions that AEL’s yearly sales currently exceed R6-billion and the company’s portfolio has been diversified to decrease AEL’s dependence on the South African narrow-reef market through substantial growth of AEL’s share of the South African opencast surface-mining market in the last five years.
“This is an explosives-intensive market and additional ammonia offloading capacity was required to leave sufficient spare capacity for further future growth in this market,” he adds.
Johnson Controls explains that the high-pressure ammonia gas generated by the compressors is used to displace the liquid ammonia from the railway storage bullets. The high-pressure liquid ammonia being pushed from the rail bullets is then piped through to an expansion valve near the low-pressure storage vessel, which is kept at atmospheric pressure and at a temperature of about –33 °C. New piping, with a larger diameter, will be required to increase the capacity of the line to the storage tank.

Hattingh identifies three critical success factors for this project.
“Firstly, this is a schedule-driven project and long-lead items like the compressor packages had to be selected and ordered during the basic engineering phase to avoid impact on the schedule. Secondly, integrating and fitting new equipment and piping, literally at the middle of an existing plant, was made possible using three-dimensional (3D) computer-aided design and presenting a 3D model of the changes to the client before finalising the detailed design.

“Finally, ammonia is a hazardous chemical, which makes safety key in this process. Hence, the design and specification of this type of plant requires knowledge and experience of the relevant standards, codes and statutory requirements to ensure a safe and reliable facility,” he notes.

Johnson Controls have global experience in dealing with ammonia offloading and storage and in meeting the safety and performance requirements of this application. Burnie notes that Johnson Controls’ strong, highly knowledgeable technical team in South Africa will provide the necessary configuration, implemen-tation, commissioning and maintenance support for AEL.
“Good progress is also being made in the construction of the compressor housing. The delivery of the Johnson Controls team to date has also been good. The team’s communication is excellent and the team members have set high standards,” notes Burnie.

Burnie further mentions that the project is pushing to tie in with the full recommissioning of the offloading facilities in the second quarter of 2014.
“Safety is key for AEL and after the consideration of risk in terms of safety – specifically on maintaining the integrity of the storage tank – we have decided to take it offline in the second quarter of 2014 to facilitate the installation of the new pipework,” he points out.

“The time of return on investment for this project is projected at four years and this project will ensure that AEL’s supply of ammonia remains reliable.”

Edited by Martin Zhuwakinyu
Creamer Media Senior Deputy Editor

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