The Sishen mine is located 30km away from the town of Kathu in the Northern Cape Province, 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. Kumba Iron Ore holds a 76.3% interest in Sishen Iron Ore Company Proprietary Limited (SIOC), which owns a 100% stake in the Sishen mine. The remaining interest is held by black economic empowerment (BEE) shareholders, including Exxaro Resources and SIOC Community Development Trust. Anglo South Africa owns a 69.7% interest in Kumba Iron Ore. The Kolomela iron ore mine is another operation of Kumba Iron Ore in Northern Cape.
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 during 60 years of the mine’s operation.
The life of Sishen mine is estimated to be 13 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
The 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 Sishen in 2019 was 71:29. 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 proven and probable ore reserves at the mine were estimated to be 519.4Mt, including 507.1Mt from open-pit and 12.2Mt from run-of-mine buffer stockpiles), as of 31 December 2019.
The mine employed 4,370 permanent full-time workers and 4,306 contractors for the mining operations during 2019.
The mine produced 29.2Mt in 2019.
Mining and processing of iron ore
The Sishen mine employs the open-pit mining method involving drill and blast. The mined ore is trucked to the nearby beneficiation plant.
The mine uses a fleet of P101-4100 shovels and 960 trucks.
Strong performance of the 2,800 shovel fleet in 2019 allowed the mine to exceed equipment efficiency targets.
The owner fleet efficiency of the mining operation increased from 65% in 2018 to 68% in 2019.
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 facility 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 a 50tph modular beneficiation plant based on UHDMS technology for the Sishen mine as part of this initiative.
The Sishen Jig Plant was officially opened in November 2008, while the UHDMS pilot plant at the mine became operational in the fourth quarter of 2013. The feasibility analysis for UHDMS is extended to the second half of 2020 to reassess a significant portion of the detailed engineering concept and to incorporate additional value-added products. The first production is expected to be completed in the first half of 2023.
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
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 the 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 the 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 dense medium separation plant (DMS) achieved nameplate production capacity of 28.4Mt in 2008, which increased to 29Mt in 2009.