A look at slag handling case studies with Vortex Global…

As featured in Global Cement
by Kevin R. Peterson

Original slag can be categorized as ferrous or non-ferrous. Ferrous slag, accounting for around 90% of all slag, comes from iron and steel production. Of these, blast furnace slag is typically blended with rocks and sand for use as a road base. It can also be finely ground and added to cement to increase strength, while reducing concrete permeability and the clinker factor (CO2 emissions). Electric arc furnace slag is typically blended with fly ash and lime to be used as pavement material or construction fill, while oxygen furnace slag is typically blended with fly ash and lime as a pavement material or soil conditioner. Slag offers advantages when used in road construction compared to natural aggregates. It is harder and more compact and wears less rapidly, offering a longer life. It retains its adhesiveness with wear, not becoming smooth or slippery. One disadvantage is its high density, which leads to high transportation costs.

Producers of secondary steel rely heavily on synthetic slag, a critical component of the secondary steel-making process. It is slag that has been crushed, blended and refined such that it draws out impurities and reduces the sulphur level, making the steel purer and stronger. Synthetic slag also reduces the melting temperature of steel, which saves energy. It enhances liquidity, shortens production time and chemically protects the liquid steel during the casting process.

Slag handling case studies
All slags are abrasive, which should be taken into consideration when purchasing handling equipment for them. When a major synthetic slag producer made the decision to build a new facility in the central US, it chose Vortex Global as a supplier for slide gates and telescoping loading spouts.

Slide Gates: The client’s process involves blending dry materials. Vortex’s Titan Slide Gates were installed beneath its silos to dose material to conveyors. The slide gates have abrasion-resistant blade and inlet liners to extend service life and displacement end pockets that prevent material from packing and wearing the end seals upon gate closure. In addition, wear-compensating ‘live loaded’ bonnet seals limit material migration to the bonnet area and to the atmosphere.

Loading Spouts: Vortex also supplied loading spouts to load bulk material into silo trucks. The four-cable hoist drive offers maximum stability and improved cable service over traditional two and three-cable systems. A motor brake prohibits the cable from ‘jumping the pully,’ decreasing downtime. CNC-machined pulleys ensure rounded edges and properly sized cable grooves, in contrast to traditional spouts that can have sharp-edged pulleys and inconsistent grooves that cause cables to bind or overlap.

Filtration System: The client also purchased a Vortex Filter as its facility is located near a town. The client wanted to ensure that it contained the dust from the loading process, both for the benefit of both residents and its own workforce. As material is loaded, a fan on the filter draws fine dust upwards, internally through an area between the spout cones and the outer sleeve to the filter unit. Pleated cartridges within the filter temporarily trap the dust until a pulse jet periodically liberates the dust from the cartridges, sending it back into the load. Instead of transporting the material to a dust collector, the company reintrains the dust back into the load. It is sold as part of the load, rather than being disposed of.

A second client, engaged in processing and repurposing slag as an abrasive for air-blasting, an ingredient in roofing products and a concrete additive, also opted for Vortex slide gates. It uses these to load slag dust into large bulk bags for distribution to customer sites on flatbed trailers. It also uses Vortex Telescoping Loading Spouts for bulk trailer loading. Both clients benefit from Vortex’s attention to designs that address slag abrasion and offer extended service life.

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