Eight tips to produce a consistent product

By |  December 10, 2013

A crusher manufacturer’s suggestions and best approaches to in-pit crushing.

Metso hosted an educational event earlier this month for dealers and customers at its headquarters in Columbia, S.C., drawing about 120 people from 34 dealers across the United States, Canada and Latin America. The event, called the 2013 Quarry Solutions & Industry Knowledge Expo, also attracted about 100 customer personnel, according to Metso. PP&E attended the event, as well.

Metso’s Matt Gerten, manager of application support and complex proposals, offered tips during the event on how to produce a consistent product. Here are the eight must-do’s Gerten suggested:

1. Operate at a consistent choke-fed cavity level. If you can run a crusher at a constant level with the same product and the same speed setting, you’re more likely to produce a consistent product, Gerten says.

2. Operate at a consistent closed side discharge setting. The more abrasive the material, the more the setting will wear. Check the setting consistently. Even small increases in crusher settings due to liner wear will result in product gradation changes.

3. Have a properly distributed feed. According to Gerten, all feed should be directed vertically into the center of the crusher. Poor distribution results in low crusher throughput, elongated and oversized product, adjustment ring movement and a tilted adjustment ring.

4. Have a homogenous feed stream. Make sure your fines and coarse feed are mixed properly. Producers should want a smooth gradation curve in the crusher cavity, as well as voids filled with smaller rocks to achieve good rock-on-rock interaction.

5. Have some fines present in the feed – but not too many. Gerten says you don’t want too many fines in a crusher feed, but you do want some. An excessive number of fines tends to clog the voids between the feed material. A rule of thumb Gerten suggests following: fines should represent 25 percent or less of a feed for a secondary cone crusher, and they should represent 10 percent or less of a tertiary cone’s feed.

6. Make sure your feed material is well graded. Gerten says producers should strive to avoid having a cavity full of single-size particles. For voids, he says strive for a well-graded feed so all points fit together and the cavity is dense with plenty of rock-on-rock interaction.

7. Don’t exceed the maximum feed size for the liner being used. “Trying to crush oversize feed wastes time, detracts from capacity, creates irregular liner wear profiles and imposes unnecessary stresses,” Gerten says.

8. Minimize surge loading. Surge loading of a crusher is a production enemy, he adds. Surge piles and feed hoppers can easily increase productivity by at least 10 percent.

In-pit crushing
Also at the Metso expo, dealers and customers had the opportunity to sit in on training sessions, walk around Metso equipment and participate in factory-floor demonstrations. PP&E sat in on a session about in-pit crushing. Tommi Lehtonen, senior vice president for Metso’s Mobile Equipment business unit, led the session and noted that excavators should be a producer’s top choice for loading into Metso’s portable equipment because excavators offer continuous feed and operators can actually see the crusher.

“Excavators are more affordable to run compared with wheel loaders because wheel loaders are loading and carrying,” says Lehtonen, who adds that hauling represents about 50 percent of in-pit costs. “For us, excavators would be our number one choice.”

Still, Lehtonen says there are exceptions that make loading equipment other than excavators attractive.

“Of course, at bigger operations, you might run out of excavators,” he says. “Use a face shovel or a wheel loader. This gives you more flexibility because you can use a track-mounted unit more and shorten the distance from the face. You can easily feed from different locations of the face.”

Lehtonen also says excavators can typically maintain their position for most of one day, as long as they have enough material to load.

Screen media shift
One new development at Metso is that its screen media is now being produced and shipped directly from Columbia. Before, Metso imported all media from Sweden. According to Gary Phillips, an injection mold operator, Metso has been making all molding for media in Columbia for about one year. Phillips also says Metso’s machine is capable of making about four media per hour.

Adjusting to the new economic normal
PP&E sat down with Adrian Quigg, vice president of distributor sales for Metso, at the company’s 2013 Quarry Solutions & Industry Knowledge Expo to learn more about the current health of the aggregates market, Metso’s changing role in that market and for a look ahead to ConExpo-Con/Agg.

PP&E: There’s been a lot of discussion about service at this event. Why the extra emphasis on service this year?

QUIGG: We’ve got to be careful with the word “service” because most people think of service as people who turn wrenches and go out and fix machines. At Metso, we put an “s” on the end and call it “services.” Services are everything that’s not capital equipment. It’s spare parts, wear parts and consumables, and the packages of service that go along with that.

Really, it’s a great opportunity for us to focus on [operating expenses] rather than [capital expenditures]. Customers are not spending money on new equipment like they have in years gone by. Aggregates production is still down. There is an overcapacity in the industry, but people are spending money to keep their plants running. So we have been very interested in developing our products and our direction to really support customers’ needs in the services environment.

PP&E: How important is it to elevate this services concept considering production is down, and production isn’t expected to return to previous high levels anytime soon?

QUIGG: It’s a shift in emphasis for an OEM like Metso. We are operating in the “new normal” of the industry – this lower level of aggregate production and aggregate requirement in North America. All of us – Metso and competitors alike – have to operate in a smaller-volume market. I think that’s causing our customers to look even deeper at their processes. Our customers are very keen to optimize their processes and be as efficient as they possibly can – and get every dollar and cent they can [out of their equipment].

PP&E: How does the U.S. market’s health compare with Europe and other parts of the world Metso serves?

QUIGG: The U.S. economy is flat and fragile. That’s the way we describe it. My responsibility extends down into South America, which we would say is strong in the construction environment. It is going quite well for us. Europe is a challenging place to be right now for sure. The U.S. has some stability, but there are no signs of any kind of economic turnaround that’s going to take us back to former glory. I think we’re going to live with this new normal for quite a while.

PP&E: Has Metso fully adjusted to the new normal you describe?

QUIGG: The heady days of 2006-07 won’t come back unless the economy allows it to come. We don’t expect to see those volumes again. We are busy adjusting. I wouldn’t say we’re fully adjusted. I’d say we’re in the process of adjusting.

One of the big initiatives we’ve launched – our quarry supplies initiative – is one of the ways we’re trying to adjust. This is a bunch of products – screen media, wire mesh, linings, conveyor belting, components and accessories. These have all been served as individual products over the years. If you wanted to buy these products from Metso, you had to make [as many as] five phone calls to five different places. We were not necessarily that easy to do business with.

What we’re trying to do is put them all together as a package for our distribution network so we become much easier to do business with and we can give more value through the distributor to the end customer. He can buy one package of products – maybe on a cost-per-ton basis – and be extremely well served by the distributor, but in a much more efficient way than we’ve done in the past. That’s one of the ways we’re trying to adjust to this new normal.

PP&E: Can you offer a Metso preview of ConExpo-Con/Agg?

QUIGG: We are going to show a new machine, but it’s not really in the public domain yet. I can tell you the machine is called an LT220D. It’s a secondary crushing and screening unit on tracks. It will be shown in configuration with a primary unit on tracks, which will be a complete process in two units. It’s a pretty exciting proposition to be able to produce calibrated finished products through two units.

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