Stainless-Steel Separator Proves its Mettle in Classifying Abrasive Ferrotitanium Granules
DETROIT, MI—Ferrotitanium, an additive used in steel alloys, makes steel more ductile, which allows the formation of thinner body panels for automobiles and appliances, such as washers, dryers and refrigerators. As a result, the metal has played a significant role in reducing the weight of vehicles, thereby enhancing their fuel efficiency. However, ferrotitanium is an abrasive material that can tear up process equipment in the plants where it is produced.
Take the case of Global Titanium Inc., one of the world's top 10 producers of ferrotitanium. The company produces ferrotitanium in granular form for shipment to steel producers and the product was literally tearing holes in the screen separator used to classify the granules by size. The problem was solved by installing a new stainless steel separator made by Kason Corp.
Global Titanium buys titanium scrap around the world and blends it with iron to make ferrotitanium. The materials are charged to an induction furnace and reacted to form ferrotitanium at an average temperature of about 2,650°F (1,454°C). The metal is poured into molds to form ingots that are about 5 X 5 ft (1.52 X 1.52 M) and 6 in. thick (15.24 cm) and weigh 1,900-2,000 lb (862-907 kg).
Ferrotitanium is very brittle and starts to shatter as it cools, explains Adam Perry, Global's assistant operations manager. "We put the metal through two jaw crushers, then send it to the separator for classification to 8, 10 or 12 mesh, depending on what the customer wants."
The Kason machine is a VIBROSCREEN® classifier, a circular unit that can accommodate up to five horizontal screens. Material is fed to the top screen, which separates the coarsest particles, then progressively finer material is removed by the lower screens. The entire assembly is vibrated by a high-torque, 2.5-HP gyratory motor, located below the housing, and is supported by rugged springs that allow the machine to vibrate freely without transmitting vibration to the plant floor.
Global Titanium's classifier is made entirely of stainless steel and has two 60 in. (152 cm) diameter screens, which separate oversized material for recycling to the crushers. Oversize particles migrate to the periphery of the machine and are discharged from a porthole into a chute. Finer material falls through the screen onto a deflector plate, which directs it to the middle of the next screen. The desired product is recovered from the bottom of the unit.
The VIBROSCREEN classifier replaced an old separator that operated in a similar manner, but it was made of mild steel and the ferrotitanium tore holes in the sidewall. "We had to repair the machine about once a month," says Perry. By comparison, the stainless-steel Kason separator has been online since the spring of 2004 and so far has shown no sign of wear. It was sold by Michigan Plant & Process Equipment Co., LLC.
Perry notes that the 60 in. (152 cm) diameter Kason machine also meets the company's production needs, which had outgrown the capacity of the old, 48 in. (122 cm) diameter unit. The Kason separator processes 1,200-1,500 lb/h (544-680 kg/h) of material, which is filled into 3,000-lb (1,360-kg) bags for shipment to Midwestern steel mills. A standard shipment is 45,000 lb (20,412 kg). The base of the machine is on a stand about 2 ft (61 cm) off the floor, to allow room for filling the bags. The product comes down the chute into the bag, which is set on a scale. The plant typically runs two shifts and sometimes three shifts.
Screens are changed regularly to match customer needs. For smaller particles, below 8 mesh, Global supports the fine screen on a heavier backup screen of larger mesh. "This allows us to add more weight and increase the capacity without damaging the fine screen," says Perry.
Global uses an identical VIBROSCREEN separator for screening sponge titanium, which the company receives from customers and vendors as mixed scrap that ranges from fines to rock-like chunks. This material is passed across a magnetic drum to remove ferrous metal, then crushed to the customer's requirement, which may range from 10 to 60 mesh. Fines are mixed with other material in the furnace and made into briquettes.