South Africa-based furnace supplier Tenova Pyromet says it has successfully replaced Furnace No 2’s electrode pressure rings at Assmang, four weeks ahead of schedule.

Awarded as a turnkey contract in April 2012, the project involved the verification and adjustment of designs, supply and installation of lower electrode equipment, including pressure rings and heat shields, manufactured from stainless steel, as opposed to the mild steel of the original equipment.

The conversion to stainless steel was necessary to enable the equipment to withstand the higher temperatures required for smelting manganese. The fast track contract was originally scheduled for a 16 week duration, but at the client’s request, was reduced to 12 weeks.

The company said that the furnace conversion was carried out without a single lost-time injury in the 1 850 manhours worked. “This was a significant achievement, given the challenging conditions of the brownfields project. We were working in very tight spaces, which required much of the rigging and moving of the heavy equipment to be carried out manually,” said Tenova Pyromet’s project manager Francois Smith.

As with the original furnace rebuild, the new equipment was based on the Tenova (Tagliaferri) design, which has been proven in many furnace operations worldwide since 1968.  Along with the Tenova Bateman and Tenova Pyromet technologies used, it is part of Tenova Pyromet’s portfolio of electrode technologies that are considered to be the benchmark in the furnace industry.

“The equipment was manufactured in South Africa, which facilitated meeting a tight contract schedule,” notes Smith. “In our planning, we also had to take into account working seamlessly with a number of other contractors on site,” Smith added.

In the converted 30 MVA FeMn furnace, manganese ore, from Assmang Limited’s manganese mines in South Africa’s Northern Cape, is fed with reductant into a submerged arc furnace where it is beneficiated into manganese and slag.

Tenova Pyromet was responsible for the original Furnace 2 rebuild, when the furnace was still producing ferrochrome. The 33 MVA, 29 MW furnace featured a 1 270 mm Tagliaferri electrode column and was designed to produce 69 000 tpa of ferrochrome. The rebuild took place over 10 months from December 2004 to September 2005.  The Tenova Group’s relationship with Assmang Limited, however, stretches far back to 1971, with the design and supply of two 12 MVA furnaces to produce molten slag at that time.

Assmang Limited supplies raw material to the world’s steel mills and alloy plants. Formed in 1935, it currently has three operating divisions based on its three commodities namely chrome, manganese and iron ore.