AfriSam cement meets challenges at Tharisa mine

first_imgAfriSam, a leading supplier of advanced composite cement, secured a contract in November 2011 to supply up to 22,000 m³ of readymix by road to Tharisa mine’s ZAR1 billlion chromite and platinum expansion project near Marikana in North West Province, South Africa. Work on the Tharisa expansion project started in May 2011 and the new facility will process an estimated 3.6 Mt/y of ROM ore with plant commissioning on schedule for August 2012. The Tharisa mine has the largest known single chrome resource deposit in the world.During the project peak in recent months an estimated 220 m³ of readymix was poured each day, with Cem2A-M (V42) High Strength Cement used in the readymix, which has a 35 MPa specification required for the primary crusher and 45 m diameter circular thickener, and 30 MPa for other structures. “Our challenge was to ensure a smooth supply of readymix during three big pours: 725 m³ for the SAG mill one base, followed by two pours of 687 m³ and 715 m³ for the SAG mill two bases.”The company said that the extent of the large pours as well as the need to ensure smooth supply to the project site and to AfriSam’s other customers motivated a strategic decision to supplement the existing fleet of AfriSam readymix trucks in the Rustenburg area with additional vehicles from Johannesburg. “We had two concrete pumps on site with a third concrete pump on standby for the big pours, and thereafter a concrete pump was on site from 0700 to 1800 daily for 37 consecutive days. In addition to this, AfriSam had concrete pumps on site on 42 other occasions,” AfriSam states.Civcontract Civils (Pty) Ltd is the civils contractor on the project. Among the elements that Civcon constructed using readymix supplied by AfriSam are the foundations and 21 m-high wall for the high primary crusher; a 47 m diameter by 11.3 m high circular thickener chamber, three flotation lines ranging in height from 6 m to 18 m; foundations and bases for two SAG mills as well as a bore mill – the biggest readymix pours on the project with 85 t of reinforced steel; two stockpile tunnels each 72 m long by 8 m high from the bottom of the foundation to the top of exterior walls; and a 16 m high concrete trestle to support the stockpile conveyor. Further deliveries of readymix were required for the construction of concrete bases and columns for the secondary and tertiary crushers; the foundations, columns and floor slabs for the primary and secondary spiral; the construction of a process water area comprising circular tanks ranging from 3 m to 30 m in diameter; bases and columns for steelwork for the 20 m by 20 m mill screening building, and bases and columns for structural steel work for the PGM plant. All these structures required 150 mm concrete surface beds with bund walls and sumps. A total of 2,100 t of reinforced steel was used on the project.The scope of work was increased over the duration of the project with concrete required for the construction of a 15 m diameter thickener, the secondary and tertiary crushers, the platform of the Eskom incoming 88 kVA feed substation, outgoing 11 kVA feed, and six mini sub stations throughout the plant yard, chrome dewatering pads comprising a 80 by 60 m surface of 150 mm reinforced with 30 MPa concrete.last_img