by Jon M. Casey
For those of you who are not familiar with Tim Holmberg, owner of Dakota Equipment Manufacturing Incorporated (DEMI Equipment) of Cresbard, SD, we had the opportunity to learn more about Tim, his company and his innovative approaches to aggregate industry problem solving, with the introduction of a new piece of equipment on the Discovery Channel TV series Gold Rush. It seems that the installation of a DEMI GR5120 wet, vibratory material feeder, featuring DEMI’s patented Grizzly Spring Fingers, has benefitted production at the 316 Mining, LLC job site, compared to traditional placer mining equipment. The unit’s design was collaboration between Holmberg and Dave Turin, who oversees mining and production for 316 Mining, LLC, one of the show’s featured companies.
History of DEMI Equipment
Holmberg, who has been a part of the aggregate industry equipment manufacturing scene for more than 27 years, left his father’s family owned, Arizona based, steel fabrication business in 2012 to set out on his own. He established his own fabrication location near Cresbard, SD. Holmberg, who is known for his creativity and patented Grizzly Spring Fingers, specializes in innovative equipment design and fabrication. His company also has a knack for refurbishing used equipment back to like-new condition. Holmberg, along with his wife Martha and their son Tyler, work side by side designing, fabricating and restoring aggregate equipment of all kinds. Holmberg’s daughter Abigail (9) is not a part of the business as such, but she has the opportunity to travel with the family at various times when not attending school. His older daughter Madison (16) occasionally operates the company’s 10,000-pound capacity telehandler forklift by helping to position them in the man basket, around the equipment while they are painting.
Gold Rush Project
Recently, one example of DEMI Equipment’s expertise and innovative capabilities materialized when Tim approached Turin about the possibility of developing a new piece of cleaning/separation equipment to help them at their new job site. Since Holmberg is a regular viewer of the Gold Rush TV show, he had watched the Season 6 episode where the Hoffman crew had done exploratory work at a new site in eastern Oregon to determine if it might be a more viable and productive site for gold production. Not only did it seem to hold more potential but it also has more clay imbedded boulders 24-inches and larger mixed in with the raw material. This was unlike the alluvial deposits in the Yukon. With this in mind, it seemed to Holmberg that a new form of primary screening or separation would be helpful to secure the optimum amount of gold ore from the site.
Holmberg sent off a social media message via LinkedIn to Turin, suggesting he might have some ideas on how to help them with their processing plant needs utilizing his Grizzly Spring Finger product. Much to Holmberg’s surprise, Turin responded personally. He agreed that the two might get together to share some ideas on how to make their production capabilities more efficient and profitable.
Holmberg said that initially, Turin really had some variation of a De-Rocker or Wave Bed in mind. However, after weighing the return on investment of units like these, a feeder of some kind seemed like the more practical solution for washing these very large boulders that they had not experienced at their other sites. The clay surrounding these boulders could be holding the flakey gold they were seeking.
Turin said that his background in the aggregate industry at his family quarry and paving business in Oregon, gave him an opportunity to become familiar with the Grizzly Finger technology, but he had never seen it used in the placer mining industry. After thinking on it for a couple of weeks, Turin asked himself, “Why not?” Why not use this in conjunction with a wet wash system?
Turin arranged to meet with Holmberg so together they could work on plans for a custom designed feeder. Each of them had some innovative ideas on what a preliminary washing and screening feeder might look like. After a few design and layout sessions, DEMI began building the new GR5120 material feeder using a somewhat standard Lippmann-Milwaukee vibratory grizzly feeder as the initial platform for the custom-built unit.
It was Turin’s and Holmberg’s plan to build a feeder that would effectively process the larger gold bearing boulders while at the same time it would begin the washing and sorting process that ultimately takes place on the wet screen system known as “Monster Red.” It was their objective to build a feeder to process sticky oversized material, one without the potential for continual blockages and downtime often plaguing this process of most aggregate mining operations. DEMI Grizzly Spring Fingers were the ideal solution to this problem.
Once the decision was made to go ahead with Turin’s final design, work on the project began immediately. Tim contacted Bob Turner at Lippmann-Milwaukee, Inc. to secure a vibratory grizzly feeder (VGF) shell to use as the primary component of the system. DEMI had a little over three weeks to build and install the unit during the filming of Gold Rush Season 7. Tim, along with Tyler and Martha all worked together to make this unique project a success.
How it works
Holmberg explained that the raw material is dumped into the infeed of the GR5120 where the vibratory action of the Lippmann feeder moves material down a high impact, coated, steel surface while it is being washed from overhead by a series of six parallel spray units. Once the material reaches the discharge end of the plate, the undersized material falls through the Grizzly Spring Fingers with the overs falling off to a stockpile for other use. From there, the washed material is discharged into an EIW Blade Mill, and then dropped onto the infeed side of “Monster Red,” a specially designed wet screening system developed by MSI Gold Mining Equipment.
Holmberg said the key to success with the new feeder is the ability of the unit’s Grizzly Spring Fingers to discharge the oversized, unwanted aggregate, without blinding. With conventional grizzly construction, blinding becomes a problem very quickly, especially with the kind of raw material that is screened at a gold mining operation. In this instance, the patented spring fingers keep the overs bouncing along and off the end of the discharge chute.
Turin noted that the way that the DEMI GR5120 Grizzly Spring Finger feeder processed the material as it initially entered the sluicing process, was a tremendous improvement over a traditional conventional grizzly dump and belt feeder set up, used widely in the placer mining industry. “In my opinion, the DEMI feeder was a huge improvement over the belt feeder,” he said.
Turin said that working with Tim was a valuable experience because Tim was able to help solve a specific problem and by working together, they were able to come up with a solution that worked extremely well. For more information on DEMI Equipment, visit www.demiequipment.com or contact Tim Holmberg at firstname.lastname@example.org or cell 605-290-7106.