News from Schwing Bioset

Schwing Bioset Featured in International Mining

 

Schwing Bioset, Inc. is excited to be featured in the Slurry Pumping section of International Mining's December issue.

The article discusses Schwing Bioset's recently commissioned pumps for a backfill application at Volcan Compañía Minera's Andaychagua mine, as well as the new piston pump installation at OCI Chemical Corp's Big Island Mine.

View the Slurry Pumping section where Schwing Bioset's projects are discussed (starting on page 36).

View the entire International Mining December issue.

You can read more about these projects on our blog.  To learn more about Schwing Bioset's Mining Solutions, contact Miguel Jahncke or visit our Mining Pumps page.

 

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Tags: Piston Pumps, Mining, Mining Pumps, Paste Backfilling

Upgrading a Reliable Necessity - Piston Pumps at the Greeley WWTP

 

Written by Joshua DiValentino, December 2, 2015

The City of Greeley, Colorado, wastewater treatment facility recently implemented a series of strategic upgrades and major improvements were made to the Biosolids Facility. The Greeley facility repurposes its dewatered biosolids cake by trucking it for land application into remote Northern Colorado. The existing Schwing Bioset piston pump located in the sludge dewatering building had been in operation for 20 years and was a key component of this process.

The Greeley facility had relied on its sole Schwing Bioset KSP 25 cake pump for two decades prior to the upgrades. During that time, the existing pump was the only means of transportation for dewatered biosolids between the centrifuge dewatering equipment and the truck loading bin. The piston pump could have been a “bottle-neck” for a facility with limited storage capacity. However, the existing pump provided an exceptionally high level of uptime over its operational life at Greeley, with minimal wear part consumption.   

By 2014-15 the sole KSP 25 had been in operation since the mid 90’s. The City of Greeley facility, working on a larger plant upgrade, decided to implement a new pumping system for the coming decades. Greeley once again chose to invest in a Schwing Bioset KSP Piston pump.

In order to be as cost effective as possible, but also provide maximum redundancy for the foreseeable future, Greeley chose to purchase a new KSP 25, as well as upgrade the existing KSP unit to modern standards. The existing pump was upgraded to match the new KSP unit with control modifications, and upgraded safety features offer easier remote operation and even longer wear part life. The existing unit was also outfitted with a new Hydraulic Power Unit, offering modern hydraulic feed pumps and unlimited control variability.  The two pumps provide redundancy and additional capacity for growth, as well as a modern control network with the current plant SCADA.

Schwing Bioset KSP Municipal Piston Pump  Schwing Bioset Hydraulic Power Pack

The new pump system included a Hydraulic Power Pack, a Twin Screw Feeder, the Control Panel, and of course the Piston Pump. The Schwing Bioset services team worked with the installing contractor and Greeley personnel to integrate the updated control system features on both pumps with the plant MCC.  The new Schwing Bioset KSP cake pumping system (complete with two fully-operational pumps) was turned over to the City of Greeley in the fall of 2015.       

To learn more about this project specifically or learn more about our pumps, please contact this blog’s author, Josh DiValentino, call 715.247.3433, and/or visit our website here: SBI Municipal Pumps.

 

Tags: Piston Pumps, Biosolids, Wastewater Treatment, Pumps, Municipal Pumps

Continuous Improvement with New Pumps at Volcan Compañía Minera

 

Written by Miguel Jahncke, October 6, 2015 (ver la versión española de abajo)

At an auction in 1997, Volcan Compañía Minera S.A. acquired Empresa Minera Mahr Tunel SA, which owned the San Cristobal and Andaychagua mines. After several other acquisitions and expansions, Volcan Compania Minera SAA has become one of the top ten producers of zinc, silver, and lead in the world.

Ticlio is high in the Peruvian Andes at over 4,800 meters above sea level. The history of the mining operations in Ticlio, which are now part of the Volcan operating units, dates back to 1943 when the first mining operations began in this area. After more than half a century, these mines continue to contribute to the economic growth for not only the area but for Volcan as well.

Andaychagua Mines

Working at these elevations is not easy. It’s made even more difficult because of the necessary extracting procedures at Andaychagua, where they are utilizing descending cut and fill mining methods. This mining method requires the use of cemented tailings filled with crushed waste rock and large amounts of steel rebar, creating strong roof support slabs to protect the miners and the mining process below.

Andaychagua has relied on this mining method for many years using Schwing pumps, which have provided reliable service for over 10 years. To keep operations running smoothly, Schwing Bioset recently supplied a new pair of KSP 65 HPR industrial pumping units with 400 HP power units to replace the trailer mounted pumps. These new industrial grade pumps will allow Andaychagua to extend the replacement interval of the pumps in the backfill operation. The first unit was commissioned last July and the second will be installed this month (October 2015). Each of these units has been set-up for dual purpose flow ranges of 46 m3/hr @ 147 bar or 70 m3/hr @ 94 bar.  

To learn more about our mining pumps or specifically about this project, please contact Miguel Jahncke (mjahncke@schwingbioset.com), call our office at +1.715.247.3433, email us, or visit our website.

 New Mining Pumps  Mining Pumps

(Miguel Jahncke, Director Global Mining at Schwing Bioset, was present during the commissioning of the first KSP65 HPR at Andaychagua in July 2015)

 

Volcan – Unidad Andaychagua – Desafiando y venciendo retos para mejora continua

Escrito por Miguel Jahncke, 6 de Octobre, 2015

La historia de las operaciones de Volcan en las Alturas del abra de Ticlio, localizado en los Andes Peruanos sobre los 4,800 msnm, se remonta al año 1943, cuando se iniciaron las primeras labores mineras en esta área. Después de más de medio siglo estas minas no solamente siguen aportando a la minería sino que continúan con su crecimiento operativo, es.

En 1997 Volcan Compañía Minera S.A. adquirió en subasta pública la Empresa Minera Mahr Túnel S.A., propietaria de las minas San Cristóbal y Andaychagua. Luego de varias otras adquisiciones y expansiones, Volcan Compañía Minera S.A.A. se ha convertido en una de las diez principales empresas productoras de zinc, plata y plomo del mundo.  

Trabajar a estas elevaciones no es fácil y más todavía cuando hay que hacerlo con el sistema de corte y relleno descendiente como se opera en la unidad Andaychagua. Este método de minado requiere del uso de relleno con relave cementado y roca fina, además de estructuras con barras de acero  para poder darle a las losas superiores la estabilidad y resistencia necesaria para soportar los trabajos de minado inferiores. Andaychagua ha dependido de este método por muchos años utilizando para el relleno unidades de bombeo Schwing. Recientemente llegaron a Andaychagua reemplazos para  las unidades de bombeo montadas sobre tráiler que operan en la unidad. Estos dos equipos de bombeo nuevos son Schwing Bioset modelo KSP65 HPR con unidades de potencia de 400 HP. La primera unidad fue comisionada en Julio pasado y la segunda será instalada durante el mes de Septiembre. Cada una de estas unidades es capaz de bombear rangos de flujos de hasta 46 m3/hr @ 147 bar o 70 m3/hr @ 94 bar.

Miguel Jahncke, Director Global de Minería de Schwing Bioset estuvo presente durante el arranque de la primera unidad KSP65 HPR en Andaychagua en Julio, 2015.

Para conocer más sobre nuestras bombas de minería o específicamente este Proyecto, contacte a Miguel Jahncke (mjahncke@schwingbioset.com) o llame directamente a nuestra oficinas +1.715.247.3433, correo electrónico, o visite nuestra página web aquí.

 

Tags: Piston Pumps, Mining, Mining Pumps, Tailings

City of Stockton WWTP - Enduring Performance, Replacing a Legacy

 

Written by Joshua DiValentino, August 27, 2015

 

The City of Stockton wastewater treatment facility has seen its fair share of challenges in recent years. When financial resources were limited, the burden fell upon the operations/maintenance staff and the existing equipment to continue operations with aging infrastructure. At this point, the piston pumps supplied by Schwing Bioset, Inc. (SBI), located in the sludge dewatering building, had been in operation for over 20 years.

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The pair of KSP 25 pumps moved dewatered sludge cake from the dewatering building out to the truck loading building, several hundred feet away. The two systems were the only means of transporting dewatered sludge cake for the 30 MGD facility. Regardless of the operational circumstances, with a resourceful operations/maintenance staff and the help of SBI technical support, the pumps remained in service with over 129,900 hours on the meter.

By 2014-15 the pair of KSP 25’s had been in operation since early 90’s, and were now nearly 25 years old. The City of Stockton facility was now emerging from a turnaround and making critical investment upgrades. Stockton once again chose to invest in Schwing Bioset Piston Pumps and replace the aged pumps with brand new KSP 25’s in the dewatering building. The new pumps have the same durability to last another thirty years, and with upgraded safety and control features that offer easier remote operation and even longer wear part life.

The SBI field services team was also hired to remove the exiting units and re-install the new pumps. The pump system was replaced by SBI in full including; Hydraulic Power Packs, Twin Screw Feeders, Control Systems, and of course the Piston Pumps. The SBI crew was able to work seamlessly with Stockton personnel to not upset active onsite operations during installation. As such, the pumps were replaced in series to phase out the old system. A completely brand new turn-key cake pumping system will be turned over to the City of Stockton this year.          

To learn more about our piston pumps or this project specifically, contact a Schwing Bioset Regional Sales Manager, call 715.247.3433, email us, and/or visit our website here.

  

Tags: Piston Pumps, Wastewater Treatment, Municipal Pumps, Dewatered Sludge Cake

New Pair of Piston Pumps for Big Island Mine

 

Written by Dale Bone, August 12, 2015

 

OCI Chemical Corporation is an industry leader in the production of soda ash, sodium percarbonate, and hydrogen peroxide. OCI’s Big Island Mine has been in operation since 1962 and is a 3.25 million short ton facility. The trona mine uses the “Room and Pillar Method,” and then they convey it to surface where it is refined into dense soda ash. The waste material is pumped back underground as far as two miles.  The tailings range from 50-63% solids. Soda ash is commonly used in glass manufacturing and powder detergent. Other uses include pulp processing, chemicals manufacturing, pH control, and food manufacturing.

OCI needed to replace aging piston pumps at its Big Island Mine near Green River, WY, and they chose to install Schwing Bioset equipment to pump their tailings underground or to surface storage facilities - on a 24/7 basis.  Because of this continuous demand, OCI spent a great deal of time and research in choosing a product and partner, and during this process they visited Schwing Bioset operations, among others. In the end, several factors drove the decision to choose Schwing Bioset piston pumps, and OCI will install two model KSP 220 pumps with XL poppet valves this fall.

According to OCI Project Manager, Mr. Jim Spurrier, the most compelling factors included Schwing Bioset’s resume of satisfied mining clients, their ability to customize programming and electrical design to integrate into OCI’s existing controls and computers, and the open loop hydraulics and hydraulic signaling incorporated in the product design.  The other important factor was that Schwing Bioset is based out of Wisconsin. The pumps and power units were built in Somerset, WI, so schematics were written in English, and the ability to get parts stocked in North America and shipped within one business day was critical, as well as having service techs in the US.

The information exchange and interaction the OCI team had with the Schwing Bioset team throughout the year-long process gave OCI the confidence that they chose the right partner for them and that they could make the project a success regardless of the challenges they face along the way.

To learn more about this project, contact this blog’s author, Dale Bone, at dbone@schwingbioset.com. For other information, call 715.247.3433, visit our website, or follow us on social media.

 

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(Equipment shown is not the actual OCI equipment)

 

Tags: Piston Pumps, Poppet Valves, Pumps, Mining, Mining Pumps, Tailings

Recent Changes Have WWTP Poised to Become a Regional Solution for Sludge Disposal

 

Recent changes have Buffalo-area’s Bird Island WWTP poised to become a regional solution for sludge disposal.

 

Written by Larry Trojak, Trojak Communications

Version also published in WE&T Magazine, July 2015

 

Sharing the Wealth

Wastewater treatment plants, like most of their business counterparts today, are being forced to cope with a barrage of challenges including rising costs, an often-demanding customer base and an ever-changing economic landscape. To effectively deal with these and other issues, a growing number of plants are thinking outside the box to improve their operations. For the Buffalo (N.Y.) Sewer Authority (BSA), that creative effort now includes supplementing their own volume of dewatered sludge with a similar (but richer) product from neighboring communities. Doing so is allowing them to dramatically reduce incineration-related fuel costs and, at the same time, assist those communities with their sludge disposal problems. Sharing biosolids? Seems only fitting from a utility serving the “City of Good Neighbors.”

 

Good Day at Black Rock

First chartered in 1937 as a primary-only treatment plant, the facility now known as the Bird Island WWTP near Buffalo’s Black Rock District was expanded to include secondary treatment in the late 1970s. According to Tom Caulfield, BSA’s administrator of capital improvements and development, the expansion was in direct response to Clean Water Act mandates.

“That massive expansion — essentially, construction of a totally new secondary treatment facility — added aeration and secondary clarification capabilities,” he says. “Even today, few people realize that Bird Island is the second largest wastewater treatment plant in all of New York state.  Only the Newtown Creek WWTP in Brooklyn’s Greenpoint community is larger. We are designed to handle a peak flow of up to 540 million gallons per day (MGD) but are currently averaging flows of about 130 mgd.”

In addition to the city of Buffalo, Bird Island WWTP serves a good number of other neighboring communities including the villages of Sloan and Depew, and the towns of West Seneca, Orchard Park, Alden, Lancaster, Cheektowaga, Elma and includes a limited amount of flow from the Town of Tonawanda. Despite that vast coverage, it was actually the nearby Town of Amherst which, by choosing to re-think its overall approach to sludge disposal, dramatically changed the complexion of Bird Island WWTP’s biosolids processing operation.

 

Plan B for Amherst

For more than a decade, the Town of Amherst had been dewatering its sludge, pelletizing it, and working hard to generate a market for it as a high-grade fertilizer product. In 2010, however, rising operational costs, coupled with aging equipment, prompted them to rethink that strategy, according to Michael Letina, BSA’s treatment plant superintendent.

“Amherst was hoping to have the same level of success with their fertilizer pellet that the Milwaukee Metropolitan Sewerage District has had with their Milorganite, but that just never happened,” he says. “Then they reached a point at which their digesters needed serious repair and, rather than incur the costs of upgrading the system, they started looking for alternatives. They determined that sending their [dewatered] waste activated sludge (WAS) here would make the most sense for them both logistically and financially.”

In early 2010 a 10-year agreement was signed, approving Amherst’s shipment of material from their facility to Bird Island. Today, about 70,000 pounds of WAS is trucked in on a daily basis from Amherst to the Black Rock location.

 

To Burn or Not to Burn

Getting Bird Island to a point where they could efficiently accept Amherst’s sludge was no small undertaking. Working through the Buffalo branch of the engineering firm Arcadis U.S., Inc., plans were drawn up and considered, with the final $2.38 million construction contract offering a couple of options for the material being delivered.

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“Essentially, the process began with construction crews cutting a hole in the15-inch thick floor of our truck weighing area, and installing a 60 cubic yard push floor bin supplied by Schwing Bioset (Somerset, WI). There, customers’ vehicles — at the beginning it was only the Town of Amherst’s trucks — could empty the dewatered WAS they were delivering,” says Letina. “The hopper contains a hydraulic push-floor that sends material through a gate where it drops into a screw feeder, then into a Schwing Bioset KSP 12V (HD) pump designed for 1,000 psi operating pressure which pushes it up to the third floor for incineration. Depending on our needs at the time, we also have the option to take that sludge out of the bin through an alternate extraction screw conveyor and drop it down to the sub basement where it can be re-wetted and sent to our digesters to produce methane.” 

Adding Amherst’s dewatered WAS to the operation was a win-win in a number of regards. Not only did it address the town’s needs to effectively dispose of its sludge, the material’s high volatile content — generally in the 76% range — proved an excellent fuel for Bird Island’s incineration effort.

“Our own biosolids are anaerobically digested and, as a result, are only about 46 percent volatile, so it takes a considerable amount of gas to burn,” says Letina. “However, putting material from Amherst on top of it is like throwing lighter fluid on an open flame. Now, we continually monitor to see whether methane production or incineration will serve us better. It’s a nice luxury to have.”

 

On the Up and Up

With the Amherst-generated cake added to the equation, steady, reliable equipment operation is key to ensuring that both plants realize the maximum benefit of the new effort.  The Schwing Bioset biosolids pump installed as part of the recent expansion has definitely risen to the challenge, says Alex Emmerson, BSA’s process coordinator.

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“The pump has its work cut out for it, taking material that is generally in the 26% to 28% solids range and sending it more than 65 feet straight up to the conveyor feeding the incinerator,” he says. “To handle issues of excessive in-line friction, Schwing Bioset also supplied an injection-ring system that lubricates the pipe wall with a small amount of fluid as it moves.”

On average, Bird Island maintains about 900,000 pounds of inventory on its secondary treatment system. They recently had a case, however, in which inventories ran low, prompting the need to curtail wasting. “That meant we had to rely solely on the ‘outside’ Biosolids and really push the pump — sometimes operating it at three times its normal speed,” says Emmerson. “Even with the added workload we were consistently pumping 8,000 pounds per hour and never had an issue. It’s definitely a key part of the operation.”

He adds that there is a certain peace of mind in knowing that the outside biosolids operation (which just recently was expanded to include a similar agreement with the Town of Tonawanda), affords them a nice contingency plan.

“Now we know we are covered if something unforeseen — like a centrifuge failure — occurs and we need to step up production using the imported biosolids to meet incinerator demand.” 

 

Money in the Bank

BSA has been prepping for growth for some time now, an effort that included a recent incinerator rehab. According to Letina, that updating, which included a new scrubber pack and burners, and carried a price tag of nearly $5 million, allows them to meet new environmental regulations that take effect in March, 2016.  However, their ability to become a regional biosolids processor — and keep costs steady in doing so — is a real source of pride.

“Much of the preliminary work for this part of the operation is the brainchild of Jim Keller our treatment plant superintendent and Roberta ‘Robbie’ Gaiek, BSA’s plant administrator,” says Caulfield.  “Because of their planning and foresight, we are already seeing the fruits of this effort.  Before the installation of the centrifuges and digesters, this plant used about 550,000 decatherms (Dth) of natural gas a year; now we are averaging about 175,000. So we’ve effectively cut our gas consumption by about 65%. With the rehabbed incinerator and addition of the higher volatile material from Amherst and Tonawanda, even with the added volumes we hope to be down around 150,000 to 160,000 Dth a year.”

The savings realized from Bird Island’s reduction in fuel costs is being reinvested in onsite projects, eliminating the need for bonding and the headaches that come with it. “More importantly,” says Caulfield, “it has also allowed us to go nine years now without a rate hike to our customers. In light of what the economy has been through, not a lot of utilities can say that.”

 

Looking Forward

Future plans under consideration —with additional anticipated savings — include a heat and power project designed to recover and re-use exhaust from the plant’s incinerators.

“The original plan was designed to incorporate the use of three waste/heat recovery boilers, says Letina.  “Once operational, the exhaust off the afterburners would create steam which would power a turbine and generate 1.5 - 2 megawatts of electricity — about 1/3 of our current load. Our electric bill right now is substantial — about $4.5 - $5 million a year. If we can save another $1.5 to $2 million annually, that money can be reinvested into the infrastructure, again avoiding bonding and rate hikes. The last few years have been challenging but definitely worth the effort. With these proposed changes and our growing role as a regional biosolids processor, this is an exciting time for Bird Island and BSA overall.”

 

To learn more about Schwing Bioset, our products and engineering, or this project specifically, please call 715-247-3433, email marketing@schwingbioset.com, view our website, or find us on social media.

To view a version of this story published in WE&T Magazine, click here.

 

 

Tags: Piston Pumps, Screw Feeders, Biosolids, Wastewater Treatment, Sewage Sludge, hydraulic push floor bin

Schwing Bioset, Inc. Expands its Leadership Position as the Class A/AA Biosolids Solution Provider

 

Published on April 14, 2015 (Somerset, WI)

Schwing Bioset, Inc. has completed another successful Beneficial Reuse installation.  The City of Immokalee, Florida, chose Schwing Bioset to provide not only its Best in Class equipment, but design and build capabilities as well.

The heart of the system is the patented Bioset process and reactor that converts raw sludge into Class AA Biosolids, making it ready for easy land application.  Licensed as a fertilizer in the state of Florida, the Class AA product produced by the Bioset process is a highly marketable and sought after product.  Millions of tons have been produced and beneficially reused by the Bioset process. 

Taking advantage of some of the other high quality products Schwing Bioset offers, Immokalee integrated their Twin Piston Pump and Dewatering Screw Press into their design.

The Immokalee Water & Sewer District Executive Director, Eva Deyo, is very pleased with the system.  “The project came in under budget and went from concept to completion much quicker than other options.  As promised, the Schwing Bioset solution has proven to be easy to operate for our staff and very cost effective to operate, and the end product is exceptional,” said Deyo.  

Schwing Bioset Regional Sales Manager, Tom Welch, is thrilled with the results of the project.  “The City of Immokalee was tremendous to work with throughout the entire process.  Their vision and understanding of the value that the Schwing Bioset solution offered was evident throughout.  They realized after investigating numerous options that you don’t have to break the bank to get state-of-the-art technology,” said Welch.

“The experience of our Design, Engineering, and Project Management Teams has really shown during the execution of this fast track project.  The Schwing Bioset Team has executed on well over $150M in projects, with 2015 proving to be our biggest year ever,” said Tom Anderson, Owner and President of Schwing Bioset.

About Schwing Bioset

For more than 25 years, Schwing Bioset has been helping wastewater treatment plants, mines, and power generation customers by engineering material handling solutions. Schwing Bioset’s custom engineered solutions can be found in hundreds of wastewater treatment plants in North America as well as mines and tunnels around the world.

For questions or more information, please contact Schwing Bioset at 715-247-3433 or marketing@schwingbioset.com, or visit the website at http://www.schwingbioset.com.

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Tags: Bioset Process, Piston Pumps, Municipal Biosolids, Beneficial Reuse, Class 'AA' Biosolids, Biosolids, Wastewater Treatment, Fertilizer, Recycled Waste, Schwing Bioset, Municipal, Screw Press

Schwing Bioset adds Synergy Controls as Mining Rep in Ontario and Manitoba

 

January 12, 2015 (Somerset, WI) 

Schwing Bioset, Inc. is pleased to announce that Synergy Controls Corporation (Sudbury, ON) has signed on as their Mining Representative in Ontario and Manitoba. Schwing Bioset is a worldwide leader in thick product pumping and material handling solutions. “Synergy Controls’ extensive knowledge of mining processes and excellent reputation in the market in serving their customer base make them a great choice as a partner,” explains Scott Springer, Schwing Bioset’s Vice President Sales & Marketing.  “They have a great presence both at the mines and with the Engineering contractors”.

Mike Gribbons (President of Synergy Controls Corporation) stated, “Schwing Bioset was our first choice for a high pressure slurry pump.  Schwing impressed us with both their experience and technology.   Coupling that with, North American made systems and a large inventory of completed pumps and spares fully complements our paste and back fill solutions. This allows our clients a “one stop shop” providing pumps, valves, instruments and control solutions.”

Miguel Jahncke (Schwing Bioset Director of Mining Solutions) is excited about this key partnership. “The Synergy Controls organization’s history of providing mining clients with engineered solutions supports Schwing Bioset’s mission of providing the best high solids content slurries transportation and handling solutions in the mining industry. Their efforts at the Ontario EPCM’s will help Schwing Bioset’s mining business globally.”

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www.synergycontrols.com                                    www.schwingbioset.com

Tags: Piston Pumps, Schwing Bioset, Pumps, Hydraulic Pumps, Mining Pumps, Slurry Pumps, Paste Backfilling, Mining Paste

Schwing Bioset Featured in E&MJ Engineering and Mining Journal

Paste: A Maturing Technology

Pump Supports Backfill Operation at Mexican Mine

engineering and mining journal

Paste backfilling, the process by which a combination of tailings, water and cementacious materials are blended and used to fill voids in underground mining operations, provides a broad range of benefits. These can include an improvement in safety, the ability to make subsequent surface development possible, a reasonable solution to the ever-present problem of what to do with tailings, and more. It’s not surprising, then, that Canadian miner Agnico-Eagle chose paste backfilling as the key tailings disposal method for one of its newest developments, the Chihuahua, Mexico-based Pinos Altos mine. But while creating the paste is one issue, getting it to the mine stopes—which in this case can be anywhere from 1.5 to 2 km away—is another one entirely. To make that happen, Agnico-Eagle turned to a pump model from Schwing Bioset (Somerset, Wisconsin, USA), and is reporting impressive performance delivering material in this around-the-clock operation.

Back into the Ground
Located in the Sierra Madre gold belt, 140 miles (225 km) west of the capital of Chihuahua state, Pinos Altos contains reserves of more than 3.5 million oz of gold and 100 million oz of silver. Operational as a surface pit since 2008—with underground mining started in 2010—the 27,180-acre (110-km2) site is expected to generate yearly outputs of 170,000 oz of gold and 2.5 million oz of silver through the year 2028. The end result of that gold milling operation is a steady stream of tailings—a volume which is currently about 2,500 t/d but could easily be doubled with an increase in production. According to Moises Palma, engineer in charge of the site’s paste plant, paste backfilling was always the method of choice for tailings disposal at Pinos Altos.

“The tailings operation was designed with this procedure in mind,” said Palma. “Currently, we take waste material by conveyor from the milling plant, and run it up an inclined belt into a batch plant. There, the tailings make their way through a process in which they are combined with cement and water to create a paste. The cement—roughly 5% of the overall mixture—is added to make the paste suitable for filling and supporting the existing underground cavities that have already been mined.  Once the correct mixture is achieved, it is dropped down into the hopper for the paste pump and ready for delivery back to the mine.”

Mine backfilling is hardly a new concept. What has changed over the years, however, is the characteristic of the backfill material itself. In the past, to accommodate the limited pumping technology available in most mines, tailings had to be turned into a slurry with a water content of 70% or more. By comparison, the paste material generated at Pinos Altos is stout, with a water content of roughly 30% and a slump generally in the 8-in. (203-mm) range.

Technology Changes the Game
The difference between what could once be pumped and what can be moved today has been mining companies’ preference for piston pumps over centrifugal pumps in tailings operations. Where other previous technology offered limited pumping pressure (often as low as 10 bar), the Schwing KSP 140 H(HD)XL pump in place at Pinos Altos provides a maximum conveying pressure of 130 bar with paste outputs up to 85 m3/hr—ideal, according to Palma, for moving the high-solids material long distances.

The Schwing pump we use here at Pinos Altos is perfect for what we do,” he said. “This is a challenging application, given the thickness of the paste, the distance it has to be pumped—currently about 1.5 km—and the pump’s almost continuous operation. Yet, we are getting a steady rate of about 126 tons of material pumped every hour—roughly 2,500 tons per day. We have been extremely pleased with that kind of performance.”

Based on the nature of the paste and the desired production rates, engineers from Schwing-Bioset recommended its XL pump option for the Pinos Altos operation. Poppets in the XL series are designed to reduce material velocity through the poppet housing.  Doing so minimizes the pressure drop through the valve housing, increases the filling efficiency of the pumping cylinders and reduces wear on the poppet discs, seats and pumping rams—all of which lead to better performance and less downtime.

To keep the pump running and the paste flowing, Pinos Altos relies on an air-cooled Model PP2400 drive unit that is powered by twin 400-hp (300-kW) motors, also supplied by Schwing Bioset. This is mounted adjacent to the pump at the base of the paste plant, and includes PLC-based controls. While the initial plan was for the pump to operate up to 10 strokes per minute and deliver 126 t/h, operations are running so smoothly that mine officials are looking to raise production another 20%.

Safety Leads the Way
As mentioned above, the decision to use a paste backfill is generally based upon the benefits that the technique provides. At Pinos Altos, it enhanced overall mine safety by providing mining crews with dramatically improved structural stability within the stope. Palma says their operating procedure for that facet of the job is far more than simply pouring mud into a hole.

“We are pumping into three main stopes and doing so in three-foot lifts with three days between pours,” he said. “Not only does that allow enough time for the paste mixture to harden, it also avoids placing the massive stress load on that cell and adjacent areas that would be present if we filled it all. This first cell alone will be taking on more than 13,000 tons of material, which is over 8,300 m3 of paste.”

To put that figure into context, 8,300 m3 ( 10,855 yd3) is enough material to bury an entire basketball court over 13 ft (4 m) deep.

Though the other two stopes currently being filled are smaller—one will hold 7,100 tons and the other 6,600 tons—they still represent a sizable movement of material from the paste plant to the mine.  Discharge into the cells is monitored via closed-circuit camera to ensure the process runs smoothly and any problems can be quickly spotted.

Looking Ahead
In addition to making the mining effort safer, paste backfilling at Pinos Altos is also addressing a number of other concerns that have plagued similar mining operations for decades. Most notable of these is the issue of how to best dispose of tailings from the cyanide-based gold recovery operation. Traditional approaches such as surface storage, while initially less expensive, can bring unwelcome environmental impacts. Paste backfilling not only solves those concerns, it does so in a manner that eliminates the mine dewatering necessary with other disposal efforts.

“This has been a very successful approach to tailings disposal for us,” said Palma. “As a result of what we do here, the mining operation is safer, there is almost no impact on the environment and, over time, it is actually a lower cost alternative to other methods. Agnico-Eagle has already started talks to boost production by almost twice what we are doing now. When that happens, we will add another pump from Schwing Bioset which will allow us to handle between 5,000 and 6,000 tons per day. We know they will be up to the task and we are excited for what lies ahead.”

Tags: Piston Pumps, Mining Pumps, Paste Backfilling, Mining Paste

Schwing Bioset Featured in Mining Magazine

Keeping the deeps dry

Carly Lovejoy explores the types and configurations of dewatering pumps used in underground mines, as well as current industry trends

Every underground mine has to deal with some degree of water ingress, and will require dewatering at one time or another during its lifecycle. How that dewatering is achieved, and the scale of the operations is largely dependent upon the mining method and design used, the depth of the mine, its location, the geology of the host rock and the type of ore being mined.

The geology of the host rock is a critical factor affecting the amount of water that needs to be removed. The porosity of the rock will determine the ability of groundwater and throughflow from natural sources such as precipitation to travel through certain layers of strata. Fractures, voids and veins can also act as conduits for water as it filters through the rock. Due to gravity, water will naturally follow through these channels, run down cave and tunnel walls and accumulate in depressions, whether natural or made-made.

Gavin Doran, general manager of sales at Sulzer Pumps (South Africa), says: “Open-pit mining sees the ingress of direct rainfall water, as well as overland or storm water flows into the operation, while underground mines see water ingress via rainfall down shafts and adits, as well as seepage of rainfall and overland flow from crack zones in geological structures, and water from pressurised aquifers that have been around for thousands of years.”

Mining in the proximity of large surface bodies of water or near coastal areas is also a concern and can lead to much greater degrees of flooding.

In addition to natural sources, water is also used at many stages in the mining process, for example, to flush cuttings from drill holes during development or production activities, and to suppress dust. This can add to the problem of naturally occurring water.

Miguel Jahncke, director of mining at Schwing Bioset, says: “Hard-rock underground mines generally have to deal with two main water sources: water that is present in the surrounding ground and enters the operation through troughs, voids, cavities, and drill holes; and water that is introduced through the mining process, through drilling, and face and muck pile hosing to suppress dust (silicosis prevention is the number one reason for keeping dust down underground).

“To prevent mining into unknown underground water bodies and ‘rivers’, development longholes are typically drilled ahead of the development headings and new mining areas to identify and eliminate, where possible, potential risks. All of the water in the mine is then collected and channelled to the lowest point through a series of channels or ditches.”

As water travels through the mine, it collects the fine particles of the rock (sometimes called fines or slimes) generated by the mining process. Downward dipping sections and working areas will collect additional water that can be pumped utilising small electric or pneumatic diaphragm pumps, or small submersible pumps. This water is pumped either to the mine dewatering channels or to one of the mine sumps. As the water reaches the lowest point of a mine, a series of settling ponds are typically used to settle the slimes, and supply cleaner water to the main sump where the main dewatering pumps are situated. These pump the water up to intermediate stages or directly up to the surface.

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Tags: Piston Pumps, Mining, Mining Pumps, Slurry Pumps