Customer Story: Rypos DPFs Provide Healthy Air at Detroit Salt Mine

Customer Story: Rypos DPFs Provide Healthy Air at Detroit Salt Mine

Project Specifics


  • Privately owned company based in Detroit, MI that mines rock
  • Operates a fleet of stationary and mobile underground mining


  • Non-metal underground mining retrofit


  • Needed to comply with MSHA regulations involving PM emissions equipment operating underground
  • Passive technology not performing
  • Employees/equipment were at serious health risk

Compliance Alternatives:

  • Move to cleaner engines or modify use of equipment
  • Passive DPF technology with an intensive maintenance program


  • Rypos has scalable solutions for diesel mobile underground equipment including large front-end loaders and boom crane equipment

The Detroit Salt Company has successfully owned and operated Michigan’s only rock salt mine since 1997. The gigantic salt mine spans over 100 years of operation, includes 1500 acres, and spans over 100 miles of roads. This privately held, woman-owned business supplies its customers in and around the state if Michigan with tons of rock salt to safely maintain the precarious winter roads of the Midwest.

In addition to size and history, what makes Detroit Salt Mine (DSM) important as a leader in the world of mining is that the mine employed the latest mining techniques including extensive air quality measures. At the time, making it one of the safest, most modern, and most efficient mines in the world. Particular attention was paid to providing the mine workers with the cleanest possible air within the mine environment.


Mine Safety and Health

Mining operations require not only people but a fleet of stationary and mobile underground mining equipment. In this tough and extremely dry environment (1% humidity/56 degree temp) the ability to keep this equipment working well to protect the workforce and to meet the Mining Safety and Health Administration (MSHA) regulations is no easy task. In May of 2008, the MSHA began to impose strict limits on the level of particulate matter (PM) in diesel emissions from mining equipment that is operated underground. Mine operations had to move to cleaner engines or modify the use of this key equipment which includes large front-end loaders and boom crane equipment that must not exceed the current 160 mg per cubic meter PM level (previously at 350 mg cubic meter PM). In the past, this meant incorporating passive DPF’s on equipment with huge maintenance requirements or finding an alternative solution.

According to Pete Graham, Director of Mining and Distribution at Detroit Salt, in 2004 the mine switched from diesel fuel to soybean oil which worked well in loaders and in Tier 1 and 2 diesel engines. They then purchased three new pieces of equipment that were Tier 3 and would not operate on the soybean oils. They needed a new solution.

“We met the folks from Rypos and learned that we could install their filters on our Tier 3 equipment and that we wouldn’t need a maintenance crew dedicated to keeping them running because they are self-cleaning,” comments Graham.“ We purchased a filter and put it on our Drill jumbo with CAT T3 engine, which is one of our biggest air polluters at the mine due to the fact that it runs constantly. The drop in emissions was so dramatic we could hardly believe it.”


The Rypos Solution at DSM

DSM was so pleased with the initial results that they purchased three more filters for their other three diesel trucks resulting in PM levels well below 160 mg PM per cubic meter; therefore well below the standard. The low maintenance, durable, and reliable filters with their regeneration/operation at any exhaust temperature worked so well at the mine that DSM had six Rypos filters operating on equipment and planned to purchase more as they add new underground equipment. The Rypos active DPFs had MSHA approval for use of HDPF/C technology in underground mining applications. The company offers scalable solutions for diesel mobile underground equipment including large front-end loaders and boom crane equipment.

“While our competitors are spending $100,000 a year on maintenance crews to keep their machinery operating to meet the regulations and using fuel additives on top of that, we haven’t had to perform any maintenance on the original filters we purchased and they are still performing better than expected,” Graham adds. “Life-cycle costs are excellent with these filters.”


About the Rypos DPF

The Rypos DPF is a highly effective self-cleaning diesel exhaust filter that uses patented electrical regeneration strategy and technology via an electrically conductive sintered metal fiber medium and electrical power from the engine of the piece of equipment to regenerate the filter as needed. The system consists of filter housing, flow control, electrical control circuit, and filter cartridges. These sintered metal fiber cartridges are capable of capturing the very fine carbon particles present in the exhaust stream, with high efficiency and high holding capacity. The filter is regenerated through the presence

of an electric current sufficient to heat the element to cause the collected soot to burn. The filter and heating element are one and the same. The electrical control circuitry automatically monitors and controls the regeneration of the filter cartridges.

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