The purpose of the Project was to satisfy process enhancement requirements. The Pre-Expansion Modular Ultra High-Density Medium Separation (UHDMS) Iron Ore Plant that was in operation at Sishen Mine could only process ~3.60 Mt/a of the JIG Plant discard.
The Expansion Project was launched to investigate the expansion of the existing Modular UHDMS facility (a Previous PBA Projects Project) to treat the entire JIG discard stream of ~6.95 Mt/a.
The PBA Projects scope for the Modular Plant Expansion included the addition of Screening, Degrit, Lump UHDMS, and Process Water Modules. For the Expansion Project, new material handling conveyors and civils were designed by Thyssenkrupp with detailing and site implementation by Stefannuti Stocks.
What was the brief to the architect Engineer/Contractor
The brief was focused on the process enhancements that were required by Sishen Mine. The solution which PBA Projects engineered accomplished this with innovative modular designed solutions that overcame a short time-line, site footprint space constraints, and integration into an operational mine to minimise downtime.
Was the project envisaged in steel from the start? If not – why was it built in steel in the end?
The project was always envisaged in steel. All the treatment plant structures that are designed by PBA Projects are designed and built from steel. Steel is utilised as it fits well into the modular design approach from the perspective of time-saving and transportability.
Give a brief description of the structural framing. What type of sections were used (e.g. hollow, cellular, I beams etc) and why?
The Structures were fabricated from S355JR Steel sections in accordance with the Red book’s hot rolled steel sections. A variety of steel section sizes were used inclusive of but not limited to: 203x133x25 UB, 254x146x31 UB, 406x178x54 UB,305x165x40UB, 152x152x23 UC, 70x70x6L, 90x90x6L, 80x80x6L,100x100x10L, 120x120x8L, 180×70 PFC, 200×75 PFC, 114.3x6CHS, 139.7x6CHS.
The flooring on the modules is steel grating and the hand railing is from commercial grade steel pipe.
The structures are designed to withstand Ultimate Limit State & Serviceability Limit State design criteria in terms of SANS 10162-1. The structure’s designs also need to incorporate strategic splits for process, modular and transport purposes. Each of the modules is transportable by truck and thus designed to withstand such criteria. Each of the modules is lifted onto and off trucks and is required to withstand lifting analyses.
As a complete structure (assembly of modules) the structures are designed to withstand the effects of vibrating equipment, with variable material loading within bins and various platework items on the plants. The platework items are designed from 350WA steel which is rubber or steel lined where required.
Were there any challenges in the fabrication of the project from the engineer’s design – if yes, please tell?
The one challenge from a modular perspective was that the screening equipment on the Primary screening module was so large that it didn’t allow for this module to be pre-assembled and transported, as assembled sections, as the other modules were. This module had subsections that were pre-assembled for ease of erection but required more on-site building.
What is special/ unusual/ innovative/ aesthetic about the steelwork/cladding in this project?
The Modular design by PBA Projects allowed the mine to continue to be fully operational while the new modules were designed, fabricated, transported and erected, minimising downtime during implementation.
The new Modules were required to integrate with the existing plant in intricate brownfields interfaces which was achieved seamlessly. For this, the full plant was 3D modelled to ensure the seamless integration.
The Modules were designed, fabricated and water tested in Cape Town, minimising project on-site assembly costs and time.
The Modules were designed to be transportable via truck from Cape Town to Kathu in the Northern Cape, ready to be stacked and bolted together, ensuring rapid site establishment and minimum on-site labour.
The Modules, incorporating vibrating equipment, were designed as low tuned structures, to minimise the mass of steel utilised in design.
How did the project team work together (e.g. contractor involved early, challenges/ ease of communication etc.)?
The Project team excelled as this was an in-house project, with all disciplines and aspects including:
- Process design,
- Electrical and Control Requirements,
- Equipment manufacture & procurement,
- Structural design and Fabrication
- Site support &
were all completed by the PBA Group of Companies, ensuring seamless integration and design quality and continuity throughout all aspects of the Project.
|Completion date of steelwork||Modular Completion in Cape Town, March 2018|
|Completion date of full project||Commissioning Completion at Sishen, November 2018|
|Tons of structural steel used||205 Tons (Purely structural columns, beams and braces)|
|Structural profiles used||Main members: 203x133x25 UB, 254x146x31 UB, 406x178x54 UB,305x165x40UB, 152x152x23 UC, 70x70x6L, 90x90x6L, 80x80x6L,100x100x10L, 120x120x8L, 180×70 PFC, 200×75 PFC, 114.3x6CHS, 139.7x6CHS|
|Flooring||Galvanised Steel Grating (Rectagrid – RS40, 30×4.5, Non-Slip, Galv) – Allowed 1.25m kick flat per 1m2.Flooring (Vastrap, 8/6, Excluding Galv or Paint)Stairtreads (Non-Slip, Sidemount with No Bullnose, Galv)|
|m2 of Flooring used from 1.||1503m283m2253 units|
|Handrailing||Steel (Ball Type, Handrail and Kneerail)|
|Linear meters of handrailing used||1014m|
|Material Holding Platework items-structurally designed||Platework items that were welded together and painted & lined where applicable|
|Tons of Platework||126 Tons|
|Client/ Developer||Sishen Iron Ore|
|Structural Engineer||PBA Projects|
|Project Manager||PBA Projects|
|Main Contractor||PBA Projects|
|Steelwork Contractor||PBA Engineering|
|Steel Erector- in Cape Town||PBA Engineering|
|Steel Erector- on site at Sishen||Stefanutti Stocks|
|Corrosion Protection |
|Corrosion Protection |