Nordberg NW Series vertical shaft impactor (VSI) plants

Nordberg® NW Series™ portable VSI plants are built around Barmac® B Series™ Vertical Shaft Impactor (VSI). Barmac is the original rock-on-rock impactor. It has become synonymous with high-quality products in quarrying and minerals processing industries.

Features
The crushing process makes Barmac VSI unique. Whereas most other types of crushers use metallic parts to crush rock, Barmac VSI uses the rock fed into the machine to crush itself. This autogenous crushing action offers the lowest possible cost per ton of any impact crushing method. The high velocity impact crushing achieved in a Barmac VSI improves the soundness and shape of the material and produces the highest quality end products on the market today. It is widely known that the more cubical your product, the better its performance in concrete, asphalt and base mixtures.

Barmac VSI is usually applied in the last phase of the crushing circuit. The quarrying and construction industry has always been Barmac VSI’s main application area with thousands of units operating around the world, followed by many demanding manufactured sand, heap leaching, pre-grinding, industrial minerals and recycling applications. This is possible because of the unique free-impact crushing and grinding action combined with the ability to accept fines in the feed and to fine-tune the crusher’s performance by simply changing the rotor speed or cascade ratio.

Benefits
High performance built around high performance crusher and screen
Electric drive with low energy costs
Good reliability with Metso’s proven quality
One button start/stop process
World wide service
Suitable for most of the road regulations

Process overview
Nordberg NW portable is typically used in multistage crushing process in the last stage. Belt conveyor transfers the feed material to the Barmac VSI which reduces them to the desired size and shape. Plant conveyor discharges the product in the stockpile.

The crushing process makes Barmac VSI unique. Whereas most other types of crushers use metallic parts to crush rock, Barmac VSI uses the rock fed into the machine to crush itself. This autogenous crushing action offers the lowest possible cost per ton of any impact crushing method.

The feed comes typically from the portable NW or mobile Lokotrack cone crusher or feeding conveyors directly to the Barmac VSI or a screen. From the cone crusher material goes back to the screen or as an end product. NW portable Barmac plant can be equipped with or without screen in open- or close circuit. The NW series with Barmac VSI is very comprehensive.

How it works
Nordberg NW portable units are made to be easily transportable from site to site by road. The chasis is on a wheel-mounted bogie with limited weight per axel. All the portable units are electrically driven.

The primary path for the feed material is through the stone lined rotor where material can be accelerated up to rotor tip speeds of 80 m/s (262 ft/s) before being discharged into the crushing chamber. Additionally, material may be cascaded into the crushing chamber, bypassing the rotor. In the most compact units a screen is easily mounted on the same chasis with a crusher.

With or without screen in open- or close circuit, the NW series with VSI Barmac is very comprehensive. A four decks screen enable to produce up to four products.