Bruks Siwertell’s drop-fed, or Rotom hammer hog, units can process many different types of materials including bark, forest residues, industrial wood waste and sawmill waste. PHOTO: BRUKS SIWERTELL
ers to obtain the smallest finished product on a single pass or one-stage pass through the grinder. “We often suggest that this is not always the most economical option long term,” Tyacke says. “Running the grinder and related equipment at full surge capacity results in frequent equipment breakdowns, high consumption of spare parts and costly maintenance repairs. Incorporating several types of equipment into the system allows the customer to protect their investment while producing a high-quality, consistent end product.” For that reason, Rawlings’ engineers have made significant changes to the hog case that allow its customers’ maintenance teams easier access to the hog rotor, sizing grates and internal case liners. Over the years, several customers have wanted a Rawlings solid rotary hog but did not have the overhead clearance in their existing footprint to allow for a clam shell opening type of machine, Rawlings says. “Our engineering team took this feedback and did a redesign of the hog case. This new model opens hydraulically from the rear of the machine, allowing full access to the hog’s internal wear components and rotor for ease of maintenance.” More recently, a customer contacted the company looking for a 2-inch minus product, as his feedstock was 12-inch minus with approximately 40 percent of the material already sized to 2-inch minus. “Af16 BIOMASS MAGAZINE | ISSUE 4, 2021
ter thoroughly looking over the project parameters, we suggested a vibratory shaker deck to screen off and separate the material, removing the 2-inch accepts prior to grinding it through a Rawlings vertical drop feed hog,” Tyacke says. “This is a common practice to reduce the amount of tonnage to the machine, resulting in cost savings of spare parts, maintenance and overall electricity costs. Simply put, it’s less expensive to screen it than grind it.”
Bruks
Bruks Siwertell is continuously improving machines and optimizes its product portfolio to meet market requirements.“The market demands a high-quality end-product with high production rate at low investment and operating cost,” says Stefanie Müller, area sales manager of Bruks Klöckner GmbH, part of Bruks Siwertell Group. Some of the demanding markets are the charcoal industry, biomass power plants, the paper industry, chipboard industry and the pellet industry. Müller notes there are several trends to which the company is responding. “When producing wood chips for charcoal, it is important to produce compact, large wood chips of up to 250 millimeters,” she says. “When chipping, the wood chips should not be compressed and there shouldn’t be too many cracks or fractures. We have developed a 1-knife rotor with a special design, allowing
