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.