Crushing the Competition: Limestone Producer Improves Operations with New Approach, Crusher

Nestled among the Sierra Nevada foothills is a quarry that’s both a piece of northern California’s history and an important contributor to its economy. Located about two hours southeast of Sacramento, Blue Mountain Minerals has been providing the region with a variety of limestone and dolomite products for more than 150 years.
    Blue Mountain provides material for industries such as agricultural, general construction, and glass. Over the years it has developed an impressive customer base and built a solid reputation for reliability and quality products. It also has a track record as a progressive and proactive company, the result of everything from comprehensive reclamation planning to voluntary early Tier 4 emissions compliance on all mining equipment.
    The forward-looking approach has helped make Blue Mountain the largest producer of limestone products in northern California, and a new vertical shaft impact (VSI) crusher from CEMCO Inc., is the machine keeping them at the top.

Leading the Way
Those close to the industry understand crushing isn’t a one-step process, nor is it likely to have one single crusher that can handle an entire operation’s needs. The process begins at the primary stage, often a jaw crusher, which can be the largest of all the machines. Next, the material goes on to the secondary stage, often a horizontal shaft impact crusher where it’s taken down to about 1¼-in. minus size. Lastly, it goes to the third stage, which in Blue Mountain’s plant is an older VSI crusher for final production. Blue Mountain is producing a narrow band product, material where the top size and bottom size are extremely close.
    Blue Mountain’s entire crew, from the president to the operations and maintenance teams, understands how important the equipment fleet is to efficiency and meeting a quarry’s production demands. Until recently, the company relied on just one old style VSI as the final step for all the materials going through the crushing circuit. The particular VSI crusher, however, wasn’t making the cut.

Not So Efficient Crushing
The existing VSI crusher wasn’t meeting expectations in terms of product quality, efficiency, and crushing cost. It produced too many fines and provided more than 45 percent material recirculation load. This inefficiency in crushing was largely a result of the inability to tailor the crushing system of the older VSI to the specific grade of limestone and dolomite. The geological characteristics of limestone and dolomite vary greatly from one area of the world to another. Blue Mountain’s region is home to a marbleized limestone, a very hard and abrasive version of the material. The marbleized characteristics lead to a smaller natural particle size.
    The old VSI was equipped with a rock shelf style of crushing rotor, and it was not adjustable to optimize for material characteristics, making a high rate of recirculation inevitable. This high recirculation rate also results in a large amount of fines, or unsalable material. For Blue Mountain, up to 10 percent of the material ended up as unusable fines.
    On top of the crushing inefficiency, the rock shelf method in the old VSI crusher required two large motors – totaling 900 hp – to operate. Fortunately, Blue Mountain’s operating staff had a plan.

The Solution
It didn’t take long for the team to see that the system just wasn’t working. Blue Mountain realized that the existing VSI crusher was producing excessive fines and production was lagging, and action was needed. If Blue Mountain split the load between two VSI crushers, they figured, a greater amount of a higher quality product would be produced. Bottom line: more profits.
    While confident in this prediction, Blue Mountain wasn’t ready to purchase a second crusher and cross their fingers. Instead, they wanted one that could handle the exceptionally hard, abrasive material coming out of his quarry. Given the quality issues, as well as excessive maintenance requirements of the existing crusher, the team was also seeking a new equipment provider.
    So, Blue Mountain chose to invest time, thought, and a little cash into about a year of material testing and researching VSI crusher options. It didn’t take long to find CEMCO Inc.

A Scientific Approach
CEMCO president Neil Hise started the company with his father, Mason, 50 years ago. Today, along with his daughter, Jennifer Hise, third-generation owner and vice president, Neil leads an experienced team on a mission to understand the science of crushing and the uniqueness of materials from one area of the world to another.
    “In my early conversations with CEMCO, it was clear they had extensive experience and a true understanding of the science of crushing. The final step was testing the product,” said Don Wilson, president of Blue Mountain Minerals. His testing phase would be the perfect opportunity to do so.
    For about a year, Blue Mountain put the VSI crusher it already had through a series of operational tweaks and applied different strategies for crushing the material to see if there were any changes the team could make on its own to improve results. Blue Mountain challenged both CEMCO and the existing crusher manufacturer to run their own tests as well. As not to disrupt Blue Mountains current production, the CEMCO team had Wilson ship samples of the material to its location in New Mexico for testing.
    CEMCO customizes every machine for each operation and material to be crushed. This is done through testing and then constructing the crusher based on two major factors: velocity of the rock after leaving the impeller, and time/energy of impact after traveling to an anvil ring or rock shelf. With countless possible combinations of these factors, testing these combinations is key. To test these factors, the team used the material samples from Blue Mountain and explored variances in rotation speeds of the motor, rotor designs, and throw distance of material from the rotor to the impact point. For example, speeding up the motor RPMs will produce smaller material sizes, while slowing it down will produce larger pieces. CEMCO went through dozens of rounds of testing before determining the optimal crusher for Blue Mountain, as well as the settings of that crusher. In the end, CEMCO’s recommended solution to Blue Mountain’s challenges was the CEMCO VSI crusher V-Twin 96, equipped with an anvil ring.
    The anvil crushing method used in the CEMCO VSI, features a semi-autogenous design that, in the simplest terms, equals a rock-lined rotor and crushing chamber with anvils. This method provides a vertical wall that has a greater ability to control the material size based on the motor RPM. For this reason, an anvil ring is intended for harder, more abrasive materials, such as those in Blue Mountain’s quarry.
     While CEMCO was able to adjust the speed and throw distances to adapt for the abrasiveness of the material being crushed, Blue Mountain’s current rock shelf method VSI crusher was unable to make such adjustments. When the results were in, Blue Mountain realized that the CEMCO VSI crusher had less than 10 percent recirculation rate as opposed to the rock shelf VSI crusher’s 45 percent. The CEMCO crusher was also able to run on less than half the horsepower. These results underscored Wilson’s confidence in his decision to partner with CEMCO, and purchase the V-Twin 96 crusher in July of 2011.
    The V-Twin 96 is right in the middle range of sizes in CEMCO’s full line of crushers, offering a maximum feed tonnage of up to 500 tn/hr. In only 15 months, the CEMCO crusher has outperformed Blue Mountain’s existing VSI crusher both in terms of production quality and overall operating costs. In the simplest terms, it has crushed the competition.

Difference in the Details
The CEMCO crusher has reduced operating costs by 2/3 over the competitive VSI crusher, increased production by more than 10 percent, and cut energy costs in half. Wilson credits this significant savings to the crusher’s design and CEMCO’s attention to specific details.
    “Overall, it’s thoughtfully designed for easier maintenance and fewer requirements,” said Wilson. “This is especially true when it comes to the rotor, which is well protected by easily replaceable wear parts. The anvils are also easy to access and change out when worn.”
    While the significant reduction in operating costs from Blue Mountain’s previous rock shelf method VSI crusher is impressive in itself, that doesn’t even factor in the better production output. Depending on the type of material, Wilson says, at minimum, the CEMCO crusher produces five percent fewer fines than the competitors’. That might not sound like a huge number, but consider the big picture. Blue Mountain produces about 600,000 tons per year of material. Five percent is 30,000 tons - of which the savings is nothing to sneeze at.
    The V-Twin 96 crusher has done the job it was brought in to do and solved production challenges, but Blue Mountain isn’t closing the book just yet. As it always does, the company is looking ahead at the future and how it can continue to evolve and grow. A big part of its future plan includes CEMCO. To start, Wilson plans to replace the old, competitive crusher with a second CEMCO VSI crusher, a move he hopes to make within the next year.
    “The CEMCO crusher reduces our operating costs and allows us to produce more saleable material, so I can easily justify the purchase of a second machine based on the fast ROI I know we’ll see,” said Wilson.
    He also likes the benefits that come when partnering with a smaller company, one that has the flexibility to better meet customer requests. “CEMCO listens to customer feedback and takes it into account with design modifications and other adjustments to build a better machine,” Wilson said. “Larger manufacturers and those that have been gobbled up by big parent companies don’t have the freedom to do that, and others simply don’t care. They’ll produce whatever makes them money, not what will make the customer money.”
    Wilson acknowledges CEMCO’s customer service as a selling point right from the start with the material testing, and customized construction based on the material characteristics. And the service hasn’t stopped with the sale. CEMCO is always available with any questions Blue Mountain may have.  
    For more information on CEMCO Inc., call 505-864-1200 or visit www.cemcoturbo.com.

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