Owing to the success of South Africa-based foundry and engineering company Thos Begbie’s Graphite Freezeline Solutions (GFS) division in the platinum sector, the division is now emphasising its entering the ferrochrome and ferromanganese markets.
The division specialises in the assistance, manufacture and installation of different types of protection for the furnace and kiln sector, including heat-resistant refractory materials in carbon, micropore carbon and various grades of synthetic graphite.
Thos Begbie GFS division manager Hercules van der Merwe says the improved corrosion-resistance GFS offers the sector has already been substantiated through various papers which have been presented on the concept.
“The proof is in the extension of furnace operating lives and the physical evidence of coolers, with almost no wear on the graphite lining.”
He explains that graphite offers properties such as high heat conductivity and mechanical stability at high temperatures without changes to its chemical composition, making it the ideal material to fit onto copper coolers that cool the graphite.
“It reduces the temperature of the slag or molten material on the hot face, which causes the molten material to ‘freeze’ onto the graphite and forms a working lining,” he says.
The working lining can vary in thickness, depending on the furnace condition, but will protect the copper components and extend the furnace life.
Using the correct grade of graphite with copper coolers results in a mutually beneficial partnership, as the graphite protects the copper from corrosion and the copper protects the graphite from oxidisation.
This enables the graphite to cool the molten material on the hot face below its solidification temperature, consequently forming a work lining on the face of the graphite “freezeline” that prolongs the copper cooler operation.
“Some unique carbon product properties are obtained by simultaneous pressing and baking,” adds Van der Merwe.
The press and bake process results in a superior combination of physical and chemical properties, including excellent abrasion and chemical resistance.
He enthuses that the process offers successful wear prevention in phosphoric, sulfuric and hydrochloric acids, as well as in caustic applications involving sodium or potassium hydroxides and other strong bases.
“Since there is no graphite manufacturer in Southern Africa, the GFS division had to optimise graphite grades and stock levels to serve local and international customers.”
Consequently, the division has forged relationships with key engineering firms and suppliers to deliver a product that is price competitive and of the highest quality, adds Van der Merwe.
“Manufacturing graphite takes anywhere between 60 and 120 days, depending on the grade, meaning the GFS division must allow for shipping and altimetry testing before the machining and fitment of the graphite components can start.”
He concludes that, since its inception in April 2019, the division has learned to optimise the supply chain as well as its in-house manufacturing methods, which has led to a “substantially reduced lead time”.