Recent ventilation projects show the importance of both airtight planning and innovating on the fly
By Jesse Morton, Technical Writer

Above, the nose fairing of the axial fan system offered by CFE Technology GmbH. The system offers fully automatic operation, a smaller overall footprint, and significantly improved airflow control over competing centrifugal fan-based solutions. (Photo: CFE)

A couple of ventilation projects recently described to E&MJ showcase bold innovation meant to ensure the success of the solutions deployed. They also revealed how important it is to have plans in place to deal with the more predictable, inescapable challenges. Based on a couple other headlines from the space, it is apparently crucial for suppliers to strive to offer both.

Turnstone Cools Hell
Turnstone Industrial Solutions, a joint venture between ABC Technology Group USA and Calandra Group LLC, completed a couple big projects in late 2019 and early 2020 that show the burgeoning capabilities of the new company.

While the company is best known for its HardLine ducting, the projects also demonstrated its engineering expertise, Bryon Cerklefskie, U.S. sales manager, Turnstone, reported.

For both jobs, Turnstone was brought in to assess and consult. It was then tasked with engineering the solutions. For both jobs, the results beat expectations and led to new contracts.
The first job was at a salt mine in New York and launched in September 2019. “We were contracted to assess the project, then tasked with developing an engineered solution,” Cerklefskie said.

The problem was the system, which used 30-in. fiberglass ducting, “had difficulty clearing out dust and fumes post blast.” That created long re-entry times, which affected productivity.

“The mine shot on third shift, and was losing a lot of production time on day shift while the blast contaminants cleared,” Cerklefskie said.

A gold mine in Washington state contracts Turnstone for more than 1,000 ft of 60-in. oval HardLine ducting. The HDPE-based polymer tubing maximizes airflow for the space available. (Photo: Turnstone)

Turnstone engineered a face ventilation system using 30-in. HardLine-MAX ducting.

“We switched to our product and then we did the engineering to calculate the optimal length of the runs and the type of transitions,” Cerklefskie said.

AirSTOP curtains were also installed. “The new configuration comes with double seams, grommet holes, extra height for muck, and zipper doors,” Turnstone reported. “All of these features allow for a better seal and lower leakage.”

When reality clashed with plans, “we had to innovate a bit,” Cerklefskie said. “The openings in there are so big, so different at times, that you’ve got to use a little bit of common sense mixed with very sound engineering, and then try it.”

Common sense told Turnstone to split the main line to the face, and to put in a damper system to “cut the air back and forth and push it different ways,” Cerklefskie said.

The result is effective evacuation of the air at the face. “It allows you to aim the air not just straight at the face, but actually to turn a corner so then you could manipulate that regulator for different times and different needs to accommodate whatever you need,” he said.

“That is something they didn’t have before. They weren’t sweeping the faces as effectively as they could have been,” Cerklefskie said. “Now the miners have control where, during these phases, if they see something a little bit different, they can adjust the system to manage it. Before they just had a start-stop button for the fan and that is it.”

After the project, an assessment followed. A hot-wire anemometer showed that the ducting in all five tunnels provided an airflow of a minimum of 15,000 cubic feet per minute (cfm).

“The logs show a drastic decrease in NO2 and CO2 concentrations using the new system, which means that the air is being circulated more effectively than before,” Turnstone reported. “On average, the new system has decreased re-entry time by two hours.”

Often, within a half hour of blasts, the area can be worked. “It went from can’t mine, can’t produce, can’t do anything until the air clears, to the miners are in there and mucking away,” Cerklefskie said. “They loved it.”

And they loved Turnstone. The salt mining company and Turnstone then moved to optimize tubing size. Next it “is going to roll out to their sister mines,” Cerklefskie said.

“We’ve gained that trust and we are going to spec out and do the full turnkey package for them,” he said. “It was a big win for us.”

At a salt mine in New York, Turnstone Industrial Solutions installs 30-in. HardLine-MAX ducting. It conducted 15,000 cfm to the face and led to a ‘big win’ contract for a turnkey package. (Photo: Turnstone Industrial Solutions)

It was the start of a streak. Turnstone partnered with a gold mine in Nevada late last year on a ventilation system optimization project that ultimately more than doubled the airflow to three faces.

Turnstone was brought in to first assess and then engineer the solution. The miner presented historical data that showed the predecessor system, on average, could only get less than half the air produced by the fans to the faces. Most of the fan fleet was more than 20 years old.

Cerklefskie said the old system’s performance was basically the sum of its parts. “They were using a flexible-type ducting that is very high resistance. It was a metal-spiral-wrapped fabric tubing,” he said. “That has got the highest resistance out there. That was a big part of it.”

In one section, the mine used 26-in. PVC hardline and 36-in. round ventbag.

PVC becomes brittle when used to conduct air, Cerklefskie said.

“This stuff is heavy and they were limited to a round profile,” he said. “It was a little less expensive and was popular back in the day.” What was saved in initial capex was later lost as opex, he said.

For example, the fan produced 24,000 cfm, and the tubing and ducting managed to deliver 9,900 cfm to the face. “Leakage and shock loss were 58.8%,” the miner reported. That translated to a pressure loss of 93%.

Turnstone and the miner upgraded the section with 48-in. oval HardLine-MAX tubing and 42-in. TwinDuct zipper ventbag. A new fan was installed.

The fan produced 41,400 cfm, and the tubing delivered 40,200 cfm to the face.

“Leakage and shock loss were 3%,” the miner reported. That translated to a pressure loss of 34.9%.

Airflow from the fan increased by 17,500 cfm or almost 73%. Airflow delivered to the face increased a whopping 30,300 cfm or 307%.

“That was achieved by combining resources with the mine. We shared data, combined expertise and then laid everything out properly,” Cerklefskie said. “We really dove in together to understand what they needed and understand it very clearly. We programmed it to succeed, rather than hoping for the best.”

The temperature at the face averaged 67°F after the upgrade, the miner reported. Which is of almost metaphysical significance, Cerklefskie said.

“It was the lowest working area in the mine and was called Hell,” he said. “At the time, it was well over 100°F.” With the humidity, few could take more than 15 minutes in the work area at a time.

“After that initial install, they brought the whole management group down and stood at the end of the tube,” Cerklefskie said, “and all of them were comfortable.”

Afterward, the miner and Turnstone upgraded another section with two faces. The section used a 2012 model, 42-in., 100-hp Jetair fan, with 38-in. PVC and 36-in. round ventbag.

The fan produced 23,000 cfm. Of that, the tubing delivered 7,300 cfm to each face. That translates to an airflow loss of 68% and a pressure loss of 81%.

The mine installed a 2018 model, 44-in., 150-hp, two-stage Spendrup fan; and 48-in. oval HardLine-MAX and 42-in. TwinDuct zipper ventbag.

The new fan produced an airflow of 44,600 cfm, an increase of 21,600 cfm or 94%. Airflow at one of the faces was 14,600 cfm, an increase of 7,300 cfm, or 100%. At the other face, it increased by 10,500 cfm, or 144%, to 17,800 cfm.

“The 48-in. HardLine-MAX and 42-in. TwinDuct zipper ventbag reduced airflow loss from 68% to 27%,” the miner reported.

Cerklefskie described such results as “pretty crazy.” At times, “they were losing like 90% of their pressure from leakage. We got the volume loss down to 5%,” he said. “That is huge.”

It proved to be a coup. “We gained a lot of trust,” Cerklefskie said. That trust brought new work. Turnstone now has product on 10 different levels at the mine.

“It paved the way for us to keep optimizing their system and implementing more, not only of our rigid tubing, but our flexible tubing, zipper couplings and other features that folks there have shied away from,” Cerklefskie said. “Now we’ve been able to come out and prove that our stuff is reliable,” he said. “They can trust us and ever since then they’ve never looked back.”

CFE’s Axial Fan Reverses Fast
CFE Technology GmbH reported its axial fan system, with an electric motor, variable pitch control and push-button-reverse functionality, is capable of reducing the time needed to go from normal to reverse operation to less than 10 minutes.

Norbert Kuhn, general manager, CFE said, the system offers “significantly higher efficiency” and “decisively increases the operational safety of the mines, while at the same time reducing costs.”

The system offers several advantages that include fully automatic operation, a smaller overall footprint, and significantly improved airflow control over competing centrifugal fan-based solutions. Heightened control comes from integrated blade adjustment, according to a report by CFE.

“This adjustment consists of a central planetary gear and bevel gears that are directly connected to the blades,” CFE reported. “In the adjustment mode, the sun gear is moved by a hydraulically or electromechanically driven swivel drive. This movement is transmitted to the bevel gears of the blades via the planetary gear, which changes the angle of the blades.”

A sensor on the rotary actuator monitors the change in angle.

Above, the rotor assembly for a CFE axial fan system to be deployed to an operation in Kazakhstan. (Photo: CFE)

“The value of the sensor is permanent compared with the proportional valve attached to the hydraulic unit and, if necessary, corrected,” CFE reported. “With this technology, the blades can be adjusted to an angle of more than 220°. This ensures reversing operation with a flow rate significantly above 80% of normal operation.”

The design was first deployed roughly a decade ago at Janina coal mine in Poland, which was operating outdated centrifugal fans. The miner needed a system that could reverse airflow in an emergency. It was also looking to cut costs.

“Two centrifugal fans with lower efficiency were replaced by one axial fan for reversing operation and variable pitch control,” Kuhn said. “This made it possible to significantly optimize the mine’s ventilation while at the same time reducing energy costs.”

The new fan motor was rated at 1.2 MW and offered a speed of 745 rpm. Auxiliary devices include the hydraulic systems for controlling the blades and brake.

The system features silencer baffles to absorb sound. Dedicated centrifugal fans in external arrangement cool the drive motors.

The system is designed for optimal operations in various contingencies. It has an emergency power supply, and an integrated emergency backup fan on standby. If the main power supply goes, the impeller blades return to a neutral position and the damper-louvres close. While the system was designed for unmanned operation, it can also be operated from the main control room.

The system was commissioned in February 2012. “Results after commissioning exceeded the guaranteed values in both normal and reversing operation by more than 10%,” Kuhn said. “Due to the higher efficiency and better reliability of the fans from CFE Technology GmbH, the ventilation of the mine is much more stable and the miners’ work is also safer.”

For CFE’s flagship axial fan system, with push-button reverse capability, the impeller assembly is mounted on a shaft end from the main motor. An actuator on the impeller hub then controls the blades in flight. (Photo: CFE)

Those initial results were duplicated at later deployments, including one in China and one in Belarus, he said.

“Despite the higher capital and maintenance costs, total savings of more than 15% compared to a conventional design can be achieved, so the payback period is extremely short,” Kuhn said. “This has been proven in several applications.”

Currently CFE is installing an axial fan system at a plant in Kazakhstan.

The deployment at Janina illustrates the viability of the system as well as the company’s expertise at applications engineering, Kuhn said. “CFE is able to solve almost all aerodynamic problems in the shortest time possible with programs developed in house,” he said. “This significantly shortens the planning phases and makes them more cost effective for the customer.”

Zitrón Plants US Beachhead

In 2012, Zitrón S.A. installs the 630-kW ZVN 1-30-630/8 fan system at Pajingo gold mine in Queensland, Australia. (Photo: Zitrón S.A.)

In early 2020, Zitrón S.A., headquartered in Asturias, Spain, launched the subsidiary Zitrón USA.

Zitrón’s stateside facility is located in Bluefield, West Virginia, and spans 70,000 ft2, with warehousing, manufacturing and service capabilities.

The development is part of the company’s mission to expand its global presence, according to Encarna Quesada, marketing director, Zitrón S.A.

“The goal is to meet the growing demand from the North American market,” she said. “There was a real demand from the U.S. market for us to be present in the country, and we also have found a reliable local partner.”

The company, founded in 1963, is known for its custom fans. “Zitrón also provides complete solutions,” Quesada said. “Zitrón provides optimized ventilation design, manufacturing fans with varying capabilities for diverse applications.”

Joe Finn, a contracted U.S. representative of the company, described Zitrón as the world’s largest axial fan engineering and manufacturing firm.

Zitrón reported it has installed 20,000 fans in a half-century. It boasts of having a mining fan operational in the most northerly inhabited place on earth, as well as of numerous more recent projects elsewhere around the world.

For example, the supplier installed three 1,300-kW vertical fans at Booysendal platinum mine in South Africa; two 630-kW horizontal fans and switch rooms at Newmont’s Tanami mine in Australia; a 2,800-hp fan as part of a turnkey project for Minera Saucito silver mine in Mexico; a 1,200-hp, 10-ft fan at the Kilyati mine in Finland; two 1,500-hp ATEX fans and switch rooms for Polyak mine in Turkey; and a 575-kW fan at Capstone Gold mine in Mexico.

As prolific as it is, and despite offering relatively short lead times, Zitrón focuses on quality, tailored solutions made possible by its superior assets, Quesada said.

Zitrón reportedly has the world’s largest testing facility of its kind. It is longer than a football field, is AMCA certified, and can test fans up to 3,300 hp and 19 ft in diameter.

The company reportedly also has “the world’s largest database of factory performance tested fans.”

The two superlatives give Zitrón the ability to custom design fans using empirical data followed by rigorous factory acceptance testing. “Fans from 15 hp to 12,500 hp, and with diameters from 30 in. to 17 ft, are designed, fabricated, tested and supplied all over the world,” the company reported.

The KPIs from those fans prove their viability. An internal study of 4,700 fans, all larger than 48-in. in diameter, found that the mean time between impeller failures was 13,000 hours, and between motor failures was 16,600 hours. Availability was 99.9%.

Caleb Warden, sales director, Zitrón USA, said the company’s superior quality solutions arise in part from a dedicated customer focus. “Customers choose Zitrón because we are a trusted partner who will work tirelessly to deliver the optimal ventilation solution for each project,” he said. “Our passion in solving design challenges makes each project as unique as our clients.”

In 2015, Zitrón S.A. installs the massive 5,600-kW ZVNv 1-36-1400/8 fan system at the Dugald River mine in Queensland, Australia. (Photo: Zitrón S.A.)

Other than fans, Zitrón supplies diffusers, control panels, sound attenuators and winches. It also supplies safety solutions, such as dust extraction technology, which “provides safer, cost-effective control of combustible dust,” Warden said.

Zitrón offers a machine health monitoring solution for managing ventilation systems for better efficiency. “Control and monitoring systems are based on continuous acquisition of data, and help increase productivity and safety in mines,” he said. “It is a revolutionary approach that offers an efficient way of automating and optimizing mine ventilation, providing safer working conditions, productivity improvements and energy savings.”

Beyond the launch and the new partnership, the company also recently increased factory floor space. Such routine investments in capacity, R&D, and in new materials and techniques “have positioned Zitrón as the industry benchmark,” Quesada said.

Nonetheless, “our most valuable asset is the 462 professionals that make up the global Zitrón team,” she said. “We should not forget that Zitrón was built on the shoulders of our employees and our success is driven by our people.”

Above, during the pre-sink phase for a 1,200-m-deep ventilation shaft at Palabora Copper, in South Africa, water incursions occurred down to the 50-m level. To answer, Murray & Roberts Cementation use a quick-setting chemical compound, concrete lined the barrel, and resealed behind the lining. (Photo: M&RC)

M&RC Charges Ahead at Palabora
Murray & Roberts Cementation (M&RC) reported it completed the pre-sinking phase of a 1,200-m-deep ventilation shaft for Palabora Copper’s new LIFT II underground block cave mining area.

Palabora Copper, located in South Africa’s Limpopo Province, is described as the country’s sole producer of refined copper.

The shaft sinking contractor started the 8.5-m-diameter shaft in early 2019. Pre-sinking went to a depth of roughly 50 m. M&RC expects the shaft to be complete in Q3 2022.

Graham Chamberlain, project executive, mine development, M&RC, said the main challenges thus far, aside from those presented by COVID-19, were from unconsolidated rock and water.

“We had water intersections at various levels down to 50 m below surface,” he said. “The type of water inflows we encountered were from various sources underground and easily found their way into the excavation around the fractured ground.”

The company has a few solutions it deploys in such situations. “We made use of a quick-setting chemical compound in close proximity to the shaft,” Chamberlain said. “We then concrete lined the barrel and resealed behind the lining.”

Going from the pre-sink phase to the main sink phase involves removing the temporary infrastructure and installing the permanent sinking infrastructure.

“The main components are the winding plant for the kibbles and stage, the headgear and tipping arrangements, and all the services and controls systems required to operate the shaft,” Chamberlain said. “We have a separate, highly skilled in-house team that does this.”

The predicted challenges to the main sink piece relate to geology. “The other challenges are getting the teams functioning smoothly with all the new technology,” he said.

“Our preparations and methodology is to cater for the worst known condition and be ready with a quick response plan for the unknown conditions,” Chamberlain said. “From experience, we also have backup emergency plans and equipment on standby. In respect to the teams, we have chosen individuals with both a good safety and team player attitude.”

Advanced machinery in use includes high-penetration-rate hydraulic drills on robotic arms nested on the shaft-sinking stage. The arrangement allows drilling at any position in the shaft without worker contact with the drills.

“Our drilling equipment has been modified for efficiencies and noise reduction,” Chamberlain said.

Other newer solutions include the winding plant, which has been upgraded with state-of-the-art safety systems, he said. “Our explosive delivery and placement systems are also improved and apply the most modern information capturing systems.”

To deal with poor ground conditions, M&RC takes the shaft lining to the bottom of the shaft during sinking, as opposed to taking it to roughly 20 m from the bottom.

“Our lining approach is applied with the use of a modified version of the traditional shuttering and our specialized concrete mixes, which we design for this specific purpose,” Chamberlain said. “The mixes are prepared and delivered by our on-site batch plant.”

Above, a crawler crane lowers the headgear assembly during the pre-sink phase for a ventilation shaft at Palabora Copper. M&RC reports the pre-sink phase is now complete. The shaft is expected to be completed in Q3 2022. (Photo: M&RC)

Despite the size of the shaft, Chamberlain said, ultimately more time is spent by management dealing with “outside influences” than is spent internally running the project.

“You cannot spend enough time educating and communicating to all interested and affected parties,” he said. “Being involved with the community and showing tangible benefits toward local employment and skills development, coupled with supporting the local businesses in the area, have been key factors for a smooth project thus far.”