Hawaiian Cement making the most of waste material

DeRego, for one, suspects Hawaiian Cement would be importing sand by now were it not for its wet processing system.

“What sat in inventory as low-dollar material is [now] some concrete and asphalt [sand],” DeRego says. “The rest comes off of the plant and makes a number of other piles.”

The Halawa Valley Quarry

Hawaiian Cement’s Sean Haggerty says the wet processing system in place at the Halawa Valley Quarry has been a “monster” performer. Photo: P&Q Staff

Leaders at the Halawa Valley Quarry, like their counterparts on Maui, realized a production upgrade was necessary if they were going to produce highly marketable products on Oahu.

Unlike the Puunene Quarry that mines a single shelf that runs, on average, 27 ft. deep, the Halawa Valley Quarry mines from a mountain that presents a different type of rock. It’s a rather sticky material that requires continuous communication up and down the production stream ahead of the wet processing system.

“We communicate ‘too much dirt’ or ‘we’ve got to change our production process to minimize sending too much dirt to the Deister [screen],’” says Joe Lilio, a quarry supervisor at the Halawa Valley Quarry who oversees the front end of production. “Also, we check the crushers’ closed-side settings regularly just to make sure you’re not bombarding it with big rocks and putting a lot of stress on the rest of the plant. A lot of things have to get done to make it easier for everybody downstream.”

A 1,000-ton pile that’s out of spec, after all, isn’t much good.

“The beauty in Joe and [quarry supervisor] Will [Mason] communicating in order to meet these demands is Joe now takes that message to his guys who are harvesting the rock – the guys at the face – and telling them: ‘Quality starts with you,’” Haggerty says. “‘What can you do to segregate that pile and minimize the amount of dirt coming down?’ They understand quality from the face down through the primary, in through the secondary, going into the tertiary. Everybody understands that quality starts at the beginning, not just with the finished product.”

Haggerty

Still, having the wet processing system at the back end of the production stream is now a bonus.

“We used to have our concrete department wash all of what we would call ‘finished product,’” Haggerty says. “But it’s not ‘finished’ if somebody has to touch it again. That’s added costs, adding inventory. CDE has fixed that problem for us. Now, QC comments it’s ‘too clean.’”

As Haggerty describes, the Halawa Valley Quarry undoubtedly benefited from the Puunene Quarry’s experience with its wet processing system.

“There were a lot of lessons learned out of that install and that operation that we were able to bring over to our side that made an instant impact,” he says.

Perhaps the biggest thing Halawa Valley Quarry leaders learned was to galvanize their plant. In an environment surrounded by salt water where rain is expected every night, that added expense has gone a long way.

“We deal with corrosion on a daily basis,” Haggerty says. “I have a third-party contractor I retain just sandblasting and painting constantly. When we fabricated ours, we wanted to galvanize as much as possible. Of course, you’re going to pay. Short term, the cost goes up a little bit. But over the long term, we’re not replacing any of this.”

Takeaways

Although the wet processing systems in place at the two Hawaiian Cement operations are somewhat different, leaders at each have learned from each other.

“They’ll come over here and say: ‘How do you run this?’” Mason says. “Then, we’ll go over there and ask the same question. I think the back and forth cross talking is really effective. We’re learning so much from each other. It’s good they can bring knowledge. Then, we can take that information and just go with it.”

One common thread between both operations is they’ve been more successful in managing their waste material.

“Waste is not pretty,” Mason says. “We have to manage that, but it’s working out really well.”

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