Steel Construction Vol 40 No 3 - Mining, Industrial, Import/ Export | Page 20

SAISC PROJECTS Mopani Headgear “Connection in the headgear structure was designed to facilitate ease of shop fabrication and site erection. Close co-ordination was required between Hatch and the fabricator, Steel & Allied Services, in order to ensure that the strict quality control requirements were met.” Mopani Copper Mines approved the sinking of the new Synclinorium Shaft at the Nkana Mine site in Kitwe, Zambia, in 2010. The reason for the shaft was to access the Synclinorium ore body and Mopani needed to modernise the hoisting, improve the efficiency of mining operations, and required a hoisting capacity at Synclinorium of 4.0 Mtpy. In order to achieve this objective a 7.0m diameter shaft was sunk using conventional methods utilising a headgear and winders supplied by the Sinking Contractor. The permanent headgear was erected after the sinking and lining of the shaft was complete. The total project cost was USD 323 million. The permanent headgear is a 64.625m tall structure measured from collar to top of crane structure with a total mass of 1 300 tonnes. This includes the mass of the headgear structure, bin, flooring, hand railing, and stair treads but excludes all mechanical items. The headgear was designed to accommodate two skips, each with a payload of 26.5 tonnes, and a total hoisted mass of 47.5 tonnes per conveyance. A Blair Winder was selected to achieve the design hoisting requirement of 4 million tonnes per annum. Project Team Client: Mopani Copper Mine Structural Engineer: Hatch Goba Quantity Surveyor: Mopani Copper Mine Project Manager: Hatch Goba and Mopani Copper Mine A steel headgear consisting of fabricated box girder vertical columns was positioned on the centre line of the shaft together with fabricated box girder raking legs. The main framing beams were also constructed utilising fabricated box girders. The bin structure was designed to be integral with the headgear for stability particularly under emergency loading i.e. hoisting rope break condition. This structure was also clad with Chromadek coated IBR sheeting in an attempt to reduce dust and noise pollution due to the close proximity of the shaft to the local community. Connection in the headgear structure was designed to facilitate ease of shop fabrication and site erection. Close co-ordination was required between Hatch and the fabricator in order to ensure that the strict quality control requirements were met. Hatch conducted regular shop fabrication inspections to ensure that the strict quality control requirements of the project were met. Trial assembly of the components at the fabricators premises vastly minimised the risk of lack of fit to various assemblies on site. Main Contractor: Murray and Roberts Cementation Steelwork Contractor: Steel Services & Allied Industries Structural Steel Detailer/Detailing Company: Cadhouse Design Enterprises Cladding Supplier: Steel Services & Allied Industries Main Steel Erector: Murray and Roberts Cementation Steel Erection Supervisor: Steel Services & Allied Industries 18 Steel Construction Vol. 40 No. 3 2016 The fabricated box girder design enabled the Sinking Contractor to pre-assemble each floor complete with hand railing, and included flooring (where permitted by mobile crane lifting and reach constraints). Each floor module was erected in sequence using purpose made lifting brackets and attachments, designed by Hatch to facilitate the erection. The headgear was erected and commissioned in 55 days, of which 14 days were spent on installing the compensating sheaves.