Sishen Mine, Northern Cape, South Africa
Sishen mine is located 30km away from the town of Kathu in the Northern Cape Province of South Africa. It is one of the largest open pit mines producing iron ore in the world.
Mining at Sishen is carried out as part of Anglo American's Kumba Iron ore operation. The mine accounts for the majority of Kumba's iron ore production.
The mining operation at Sishen dates back to 1953. The first ore from the mine was exported in 1976. More than 900 million tonnes (mt) of iron ore has been produced over 60 years of the mine's operation.
The life of Sishen mine is estimated to be 18 years. Expansion projects such as Sishen Lower Grade projects, SEP1B and the Sishen DMS concentrate project are in consideration to extend the life of the mine.
Geology of the Sishen mine
Sishen mine extracts the lump ore from a large haematite ore body hosted by a Lake Superior-type banded iron formation (BIF) called Kuruman Formation of the Asbestos Hills Subgroup. The lump to fine ratio of the Sishen ore is 60:40. The ore body measures approximately 14km long, 3.2km wide and 400m deep.
The medium and lower grade iron ore at Sishen is found in the Gamagara Formation and occurs deeply towards the south of the higher grade ore deposit.
Mine reserves and production at Sishen
The ore reserves at Sishen as on 31 December 2012 stood at 918.9mt.
The mine produced 33.7mt of iron ore with a stripping ratio of 3.5 in 2012. The cash cost per tonne produced during the year was $25.60. The mine employed 5,303 full time workers and 2,910 contractors for the mining operations during 2012.
The production from the mine in 2011 had totalled 38.9mt.
Mining and processing of iron ore
The Sishen mine employs open pit mining method involving drill and blast. The mined ore is trucked to the nearby beneficiation plant.
The mine uses a fleet of 78 Komatsu 960 and 860e haul trucks fitted with collision avoidance systems.
The ore undergoes Dense Media Separation (DMS) and the jig processes at the beneficiation plant. It is crushed, washed and separated into coarse, medium and fine materials by wet screening. The Sishen Jig Plant is the largest jig plant of its kind in the world.
A joint venture development agreement was signed between Kumba and Exxaro in April 2012 to utilise the latter's ultra-high dense-medium separation (UHDMS) technology in Kumba operation. Tenova Bateman has been awarded a contract to supply 50 tonnes per hour (t/h) modular beneficiation plant based on UHDMS technology for the Sishen mine as part of this initiative.
The UHDMS technology that promises higher separation efficiency is expected to be demonstrated at Sishen by end of 2013.
Sishen currently has a production capacity of 41 million tonnes per annum (mtpa).
The products of Sishen include 25mm 65% Fe lump (DMS), 25mm 64% Fe lump (jig plant), 27mm and 20mm 66% Fe lump, and 8mm 64.5% Fe fines.
Future expansion projects at Sishen
The Kalahari Manganese Field, located in Northern Cape Province, about 700km southwest of Johannesburg, contains around 80% of the world's known high-grade manganese ore reserves.
Several brownfield expansion projects are in the pipeline for Sishen's operation. The projects include the Sishen lower-grade project phases 1 & 2, SEP1B, and the Sishen DMS concentrate project.
The Sishen lower-grade project phase 1, which is in concept study stage, aims at producing 1.7mtpa or iron ore by processing the waste material from the Sishen jig plant. First production from the project is expected by 2019.
The Sishen lower-grade project phase 2 is currently in exploration stage. The project aims at producing an additional 4.3mtpa of iron ore for 20 years with the use of advanced beneficiation technology from the lower grade Sishen resources previously classified as waste. The project is expected to begin production in 2019.
The SEP1B project, which is under implementation, will process the 0.2mm to 1mm fraction of the jig plant ROM feed which is being currently discarded. The project is expected to be completed in 2013. It will produce an additional 0.73mtpa while increasing the product yield of the jig plant by 3% when completed.
The Sishen DMS concentrate project is currently in feasibility stage. It will produce high-grade iron ore concentrate from the tailings of the DMS plant. It is expected to produce 1.1mtpa of less than 200 micron fraction or pellet feed by 2018, which will be blended with Sishen mine fines.
The production from the project can be ramped up to 2.9mtpa by 2020 with treatment of the jig tailings.