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Portable screen provides ‘big’ boost for the Big Boy

Lonesome Prairie Sand & Gravel has been operating since 1982. The company was founded with the purpose of providing high quality products to its customers in a safe and highly efficient manner. It has earned a reputation as a top aggregates provider throughout Saskatchewan and Alberta, in the west of Canada.

The mountains of sand are especially troublesome for the company’s operation in Big Boy Quarry, Wakaw, Saskatchewan, one of five pits the company owns. The quarry is far deeper than most pits. The average quarry in the region drops three to nine metres (10 to 30 feet). Big Boy Quarry is more than 30m (100 feet) deep.

Profits are a challenge because, although crews sift through more than one million tonnes of material every year, only about 200,000 to 300,000 tonnes is saleable aggregates for concrete and asphalt. In most circumstances, the quarry would also sell the sand, but because the company is too far from large sand-buying markets, it is only able to sell about 50,000 tonnes a year, severely limiting profitability.

The site is in western Canada, where pits are generally non-sustainable and gravel is becoming harder and harder to find. This means most aggregates operations must use portable equipment so they can quickly move to the next job. A single Lonesome Prairie crew could operate in as many as 15 to 20 pits per year, spending anywhere from two weeks to two months in a single spot, so it’s important that they can set up, take down and transport everything in as little time as possible.

{{quote-A:R-W:215-I:7-Q:"We’re always looking for ways to improve our customers’ profits and productivity"-WHO:Steven Cwiak, sales manager at Haver & Boecker}}Lonesome Prairie had been using two portable vibrating screens in the Wakaw location, but the equipment wasn’t holding up to conditions, causing decreased performance and productivity. The sandy environment required screening equipment that not only produced maximum amounts of saleable rock, but also stood up to blinding and surging to eliminate material contamination. The machines were regularly bogged down, leading to sand going through the crushers and contaminating the saleable material, resulting in wasted product and lost profit.

To maximise yields, the operation used screen media with opening sizes as large as seven, eight and nine millimetres and overloaded the screens with as much as 5000 tonnes of material per day. The larger opening sizes meant smaller rock – about five to eight per cent of the saleable rock – was falling through with the sand the operation considers waste material. The issue cost Lonesome Prairie about $CAD200 ($AUD212.67) per hour in production losses.

The larger openings were a quick fix for the material surges, as well as blinding problems exacerbated by weather. Regular rain, frost and snow dampen the sand, contributing to material clumping together and blinding screen media.

Production rates and lost revenue were only compounded by increased maintenance costs. The sand caused the vibrating screens to wear quickly and require nearly continuous replacement of screen media. Crews needed to change screen media every two weeks, resulting in two to three hours of downtime and 1000 to 1500 tonnes of lost production for each change-out.

“The many issues were frustrating for our crew and our customers,” said Henry Derksen, the Lonesome Prairie Sand & Gravel operations manager. “Contamination meant our material wasn’t as clean as it should be, and we were concerned the issues would drive away our buyers. Production amounts were also not as high as we wanted them to be. We were tired of throwing away rock, so we began looking for a solution.”

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A bespoke solution

Lonesome Prairie management approached Hikon Industries, an equipment manufacturer and supplier it works with regularly that specialises in manufacturing aggregates and frac sand processing and handling equipment.

The company’s product line includes portable chassis for screen decks, jaw crushers and cone crushers, as well as feeder plants, conveyors, cold bin feeders and surge bins. Hikon also completes custom fabrication projects to suit individual customer needs.

Lonesome Prairie personnel explained to the Hikon representatives what they were looking for: a user-friendly, portable vibrating screen that would meet production requirements and be manufactured out of as many modular components as possible to allow for inexpensive repair.

Lonesome Prairie provided its desired tonnes per hour (tph), gradation samples and other specifications, and Hikon searched for a vibrating screen to match. The dealer talked to several manufacturers, including Haver & Boecker, a company it has worked with in the past.

Hikon representatives knew Haver & Boecker had a reputation for building high quality equipment and listening to customers’ needs, and they were also aware of the company’s Tyler F-class vibrating screen, which features an advanced double eccentric shaft design, supported by four high performance, double spherical roller bearings.

The technology minimises structural vibrations and delivers a consistent stroke, virtually eliminating surging, blinding, pegging and material contamination. Hikon and Haver & Boecker agreed to work together and started to design a Tyler F-class portable plant.

“There are quite a few off-the-shelf portable vibrating screens out there,” Hikon Industries president David Hildebrandt said. “They’re often less expensive to purchase, but rarely finetuned to an individual pit. The customisation we do to match each application is important to achieve the highest levels of productivity and profitability.”

Hikon custom-built the chassis around the 6m x 3m (20’ x 6’) three-deck F-class screen. Haver & Boecker engineers factored in the desired tonnage and the material Lonesome Prairie processes to determine what the machine’s stroke should be, the speed and general mounting guidelines. Hikon took feedback from the aggregates company, including adding a specially sized jaw crusher on the chassis. Lonesome Prairie also asked that the bottom deck of the vibrating screen be end-tensioned. In the company’s operation, the design results in longer-lasting screen media and 30 per cent more productivity than side-tensioned machines.

Haver & Boecker customised the machine for Lonesome Prairie’s specific needs. When the engineering design was in place, both manufacturers got to work.

The finished system was inclined rather than horizontal, like many portable systems, allowing for a higher production capacity. The machine included a hydraulic system to lift and position the vibrating screen at the optimal angle. The F-class utilises a base frame that attaches to the chassis. Crews use the hydraulic system to set up the portable vibrating screen in less than 30 minutes, with the entire plant – including conveyors and other peripheral equipment – taking about half a day. The same task can take about two weeks for fixed equipment – which Derksen said could mean a loss of about $CAD300,000 ($AUD320,432) in production during the busy season for a 24/7 operation.


Positive tests

The F-class portable plant arrived at Big Boy Quarry in April 2016, and Lonesome Prairie began testing immediately.

The quarrying team was sceptical about the results the manufacturers had promised, thinking it was too good to be true – especially considering the warm, dry weather during initial testing. Doubts vanished when they found the single vibrating screen increased aggregates production by about 25 per cent, even as rain came and went.

The improved screening action allowed the operation to maintain needed production rates while using screen media with an open area of about 4mm, preventing waste of the smaller saleable material the company lost while using larger open-area screens.

“Price can be a problem in western Canada because our competitive market often calls for cheaper equipment that fits the budget,” Derksen said. “Despite the higher price tag, I have no doubts we’re improving profits with this machine.

“We couldn’t believe our eyes – bad weather didn’t even faze it. People don’t believe us when we tell them our costs are so far down and we’re getting more productivity out of one 20’ x 6’ vibrating screen than the 20’ x 6’ and 16’ x 6’ [5m x 2m] units we were using before.”

Derksen said the two prior units together produced about 400tph, but they were plagued with problems that often resulted in wasted or contaminated material. The F-class virtually eliminated blinding and maintained consistent G-force during surging. This boosted material processing to 500 tph, including about 300 tph to 350 tph of sand, with the rest being clean, saleable material.

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The new machine also dramatically reduced maintenance and contamination problems. Screen media change-outs went from every two weeks to every six weeks – saving the operation $10,000 per month. Replacement times on the end-tensioned bottom deck – which requires the most change-outs – dropped from two to three hours each screen media change-out to only 30 minutes. Replacement times for the top two decks stayed about the same.

Derksen said Haver & Boecker technicians helped choose the best screen media combination for his application, which has helped improve wear life and reduce contamination. He also attributed reduced change-outs to the F-class deck’s engineering, saying it spreads material better than other machines.

In addition, Derksen said Haver & Boecker technicians followed up with the company’s Pulse Vibration Analysis service on the F-class, to ensure the machine was running to factory specifications.

“We’re always looking for ways to improve our customers’ profits and productivity,” Haver & Boecker’s certified sales manager Steven Cwiak said. “Whether it involves working with another company on a custom vibrating screen, helping choose the best screen media for a job or solving maintenance challenges, we’ll never shy away from finding the best solution for our customers.”

The F-class portable plant will stay at Big Boy for some time unless Lonesome Prairie encounters similar sand and productivity problems elsewhere. Looking ahead, given the success Derksen has seen, he anticipates a fast ROI. He said he now knows whom to call to solve unique problems preventing his operation from getting the most out of mountains of sand.

Haver & Boecker’s screening, washing and pelletising solutions are available through its Australian subsidiary, headquartered in Perth.

Source: Haver & Boecker

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