Four 20 ton Inductotherm steel frame furnaces with 8 000kW Inductotherm VIP Power-Trak Power supply installed in melt shop.
Cerefco has recently completed the commissioning and start-up of four 20 ton Inductotherm steel frame furnaces with 8 000kW Inductotherm VIP Power-Trak Power supply at SA Steel Mills, a new steel making and processing mill that is based in Meyerton, Gauteng. The installation is one of the largest induction-melting systems installations in the South African market in recent years and is part of a broader vision for SA Steel Mills to build a world-class, modern, self-sustainable vertically integrated steel plant that would be energy efficient and environmentally friendly.
In the melting department SA Steel Mills have two furnace systems, each comprising of an 8MVA power supply and two 20MT Inductotherm steel frame coreless induction furnaces. The company will only have two furnaces in operation at any given time and while these are in operation the other two furnaces will be prepared for relining and the next melt
SA Steel Mills is a company within the Pro Roof Steel and Tube Group and was established because of the dilemma its sister company – Pro Roof Steel and Tube – had on their hands with the unpredictable supply of material from the only local supplier.
Management at Pro Roof Steel and Tube decided to secure the majority of their steel supply with an investment in a greenfield steel manufacturing and processing mill. The company had previously set up a smaller mill in Vereeniging producing 50 000 tons a year but this was not enough capacity, even just for its own consumption.
The Inductotherm VIP Power-Trak Power supply that provides the power for the melting furnaces can be switched between either of the two furnaces that it is connected to
Pro Roof Steel and Tube was established in 1988 and has been servicing the South African steel industry for more than 30 years supplying tubing, lip channels, roofing, rainwater goods, flat sheets, long products, gates and fencing related products are supplied to steel merchants and end users in the building, construction, transportation, engineering and agricultural sectors. Most of these products have been processed in some form by the company.
All these products need steel
Whether it is sheet, tube, coil, plate, rod or bar, all these products need steel to be processed, shaped, bent, formed or cut before the company can even think of being a processor, manufacturer or merchant and it needs a regular supply. Typically the machines used in this type of processing are hungry and need to run for long periods to make them productive and cost-effective.
From steel processing to steel making
Steel is the backbone of industry, and it follows suit as the backbone of infrastructure. Steel provides the strength to keep a building and its components standing from the ground up. Steel can be used in diverse arrays of applications, both domestic and industrial. The strength to weight ratio assists in cost savings and ensures that the structure will stand the test of time. Steel, dependent on the design and customer’s requirement, can be shaped to fit any mould. The versatility, design, and application can make a structural art piece that is appealing to the eye.
Scrap metal is used to charge the furnaces
It therefore goes without saying that countries that suffer a steel shortage will be left vulnerable. The same can be said for companies that have steel as a requirement. And those are many in the value chain.
Selecting the right unit for efficient induction melting
There are two basic types of induction melting furnaces that have been in use since the early 1900s. First came channel furnaces, operating with mains frequency, and then many foundries switched to coreless furnaces, for which a range of frequencies (from medium to high) were used. Channel furnaces were originally developed to melt brass but now are commonly used for copper, bronzes, zinc, aluminium and iron. Coreless furnaces are commonly used for virtually all metals.
Additionally, Inductotherm have supplied two 550kW sintering/holding power supplies – one each for the 8MW power supply (the input power is 8 680KVA and the output to the furnace is 8 000kW). This enables SA Steel Mills to have the full 8MVA of power on one furnace for melting, but at the same time, they can have 550kW of power on the second furnace to sinter the new lining. This ensures maximum up time and availability for each melting system. The commissioning and start-up of the Inductotherm melting equipment was done locally by Cerefco who continue to provide aftersales technical support
A coreless induction furnace operates at low, intermediate and high frequencies – from 60 to 10 000 cycles/second – and is unmatched for flexibility. It also operates by transformer action, but in this case it is similar to an air-core transformer. The primary coil induces current directly in the metal charge, which is contained in an unobstructed crucible or refractory lining. There is no internal melting loop or channel. The primary winding is a water-cooled copper coil surrounding the outside of the crucible or refractory lining.
The coreless furnace can be started cold and usually is poured empty. This greatly simplifies alloy changes and makes it possible to shut down as desired.
Inductotherm melting equipment
In the melting department SA Steel Mills have two furnace systems, each comprising of an 8MVA power supply and two 20MT Inductotherm steel frame coreless induction furnaces. The company will only have two furnaces in operation at any given time and while these are in operation the other two furnaces will be prepared for relining and the next melt.
Pre-heating of ladles
The Inductotherm VIP Power-Trak Power supply that provides the power for the melting furnaces can be switched between either of the two furnaces that it is connected to.
Additionally, Inductotherm have supplied two 550kW sintering/holding power supplies – one each for the 8MW power supply (the input power is 8 680KVA and the output to the furnace is 8 000kW). This enables SA Steel Mills to have the full 8MVA of power on one furnace for melting, but at the same time, they can have 550kW of power on the second furnace to sinter the new lining. This ensures maximum up time and availability for each melting system. The commissioning and start-up of the Inductotherm melting equipment was done locally by Cerefco who continue to provide aftersales technical support.
Reheated bar on its way for processing
Inductotherm also supplied an Inductoforge billet heater for boosting the temperature of the billets. The billet heater has a power rating of 2 250kW and the billet sizes that can be processed are 100mm x 100mm, 120mm x 120mm, 130mm x 130mm and between 3.5 metres and six metres in length. The Inductoforge is capable of processing steel at 40 ton/hour at temperatures from 900⁰ C to 1050⁰ C.
Cerefco (Pty) Ltd was established in the early ‘80s, to service the foundry, metallurgical, and industrial sectors of the Southern African Market. Cerefco (Pty) Ltd is the official representative of Inductotherm Corp.
For further details contact Cerefco on TEL: 011 845 3253 or visit www.cerefco.co.za or www.inductotherm.com
