{"id":3994,"date":"2023-02-26T00:07:06","date_gmt":"2023-02-26T00:07:06","guid":{"rendered":"https:\/\/northamericanmining.com\/?p=3994"},"modified":"2023-02-26T00:07:10","modified_gmt":"2023-02-26T00:07:10","slug":"pumping-success","status":"publish","type":"post","link":"https:\/\/northamericanmining.com\/index.php\/2023\/02\/26\/pumping-success\/","title":{"rendered":"PUMPING SUCCESS"},"content":{"rendered":"\n

Surface mine dewatering pumps may not be particularly glamorous, but they are essential.<\/em> North American Mining magazine talked to three experts about the most important factors<\/em> impacting pump selection and performance.<\/em><\/p>\n\n\n\n

By Jonathan Rowland<\/em><\/p>\n\n\n

\"\"<\/p>\n\n\n

Dewatering pumps \u201cplay a critical role in all mining operations and are therefore among the most important equipment in a mine,\u201d said Mikael Hjelm, business development manager for Mine Water Management at Sulzer, when he spoke to North American Mining<\/em> for this article, providing all the introduction needed to this significant topic. <\/p>\n\n\n\n

\u201cThe most important task of the pumps is to keep the mine dry,\u201d he continued. \u201cWater enters mines from different directions as rain, meltwater or groundwater, so if the pumps stop, the mine will fill with water. This could lead to a catastrophic flooding situation that shuts down the entire operation \u2013 with costly results.\u201d<\/p>\n\n\n\n

So, what should open-pit mine operators consider when it comes to selecting and operating their dewatering pumps? In addition to Hjelm, North American Mining spoke to Ian Ross, global product manager \u2013 Dewatering Solutions at Weir Minerals, and Ken Albaugh, director of sales and services at Xylem, to find out. <\/p>\n\n\n\n

<\/p>\n\n\n\n

Active and reactive dewatering<\/strong>
In surface mining, there are two main dewatering methods, explained Hjelm: active dewatering and reactive (or passive) dewatering.<\/p>\n\n\n\n

Active dewatering aims to lower the water table to prevent ingress of water into the mine. Depending on the amount of water to be removed and the depth of the groundwater table, either deep well borehole pumps or wellpoint systems are used. The former offers the ability to reach water tables at deep levels but are more difficult and expensive to install. In contrast, wellpoint systems are easier to install, but limited to the operational depth of the mine. <\/p>\n\n\n\n

\u201cDeeper mines would usually use borehole pumps located in deep wells surrounding the mine,\u201d continued Hjelm. \u201cThe number of wells increases with the size of the mine, with mine depths able to reach down to 400 meters to 500 m [1,312 feet to 1,640 ft]. Shallower mines may use a wellpoint system instead, connected to an electric or diesel engine, and installed at different levels on the slopes of the mine.\u201d<\/p>\n\n\n\n

In contrast, reactive dewatering removes water from existing sumps in the pit, often using a combination of pump technologies \u2013 from submersible pumps installed in the pit that transport water out of the mine, through booster stations with end-suction, axially split case double suction pumps or multistage pumps mostly installed in mobile containers or in fixed pumps station built onsite. It is these various reactive dewatering pumps that will be the focus of the remaining discussion. <\/p>\n\n\n

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A vertical turbine barge maintains proper spacing between the bottom of the pump and the sediment, which prevents\u00a0excessive wear and tear on the pump. Photo: Xylem<\/em><\/figcaption><\/figure>\n\n\n

Pump options\u00a0<\/strong>
The most common pump types used in dewatering include submersible dewatering and slurry pumps, self-priming pumps, end-suction pumps, multistage pumps, axially split case double suction pumps and vertical turbine pumps.\u00a0<\/p>\n\n\n\n

\u201cThe advantages of submersible dewatering pumps are that they are flexible, require no infrastructure, can handle dirty water in high volumes and at high heads, and are easy to move around the mine site. If higher pumping heads are required, it is also easy to connect these pumps in series,\u201d said the Sulzer expert. <\/p>\n\n\n\n

\u201cFor pit dewatering applications, we always recommend suspending a submersible dewatering pump on a barge or pontoon so, when the water level drops, the pump will not burrow into the bottom sediment. This will save the pump from excessive wear and tear, as well as significantly extending service life. <\/p>\n\n\n\n

\u201cLike submersible pumps, self-priming pumps \u2013 both driven by electric motors or diesel engines \u2013 can be flexible, easy to install and move around the site, require no infrastructure, and can handle both high volumes, high heads, and large contents of solids. They can also be installed on skids, trailers or pontoons.\u201d<\/p>\n\n\n\n

Finally, he noted, multistage ring section pumps and submersible vertical turbine pumps can be used for mine dewatering applications when higher heads are required. \u201cNormally, vertical pumps are installed on pontoons, while multistage ring section pumps are land based. Although any head requirement in an open pit mine can be handled, they are limited to handling clean water only.\u201d<\/p>\n\n\n\n

<\/p>\n\n\n

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Figure 1. Straying too far from a pump\u2019s BEP leads to premature wear, higher energy consumption, increased maintenance requirements, a reduction of overall efficiency and as a result, more downtime. Graphic: Xylem<\/em><\/figcaption><\/figure>\n\n\n

Pump selection 101\u00a0<\/strong>
\u201cFirst, understand the need,\u201d said Xylem\u2019s Ken Albaugh. \u201cThis requires a comprehensive understanding of all aspects of the application, including the location, duty conditions, and available power source, i.e., is electric more suitable than diesel, or vice versa?\u201d\u00a0<\/p>\n\n\n\n

\u201cThe type of dewatering system and pump technologies depends on the application, the characteristics and properties of the water, and whether the water is clean or dirty. Factors include the level of suspended solids, specific gravity, pH-level, salinity, and acidity,\u201d agreed Sulzer\u2019s Hjelm. \u201cYou should also consider the life of the mine. If the expected mine life is long, a more permanent and higher-end dewatering system might be appropriate, but in a mine with a shorter life span, portable and inexpensive dewatering technology might be the better option.\u201d<\/p>\n\n\n\n

Getting into details: \u201cAll pumping applications, including dewatering, share three common factors: the flow or amount of liquid to be pumped; the elevation or gravity resistance; and the distance the liquid is to be moved,\u201d Albaugh continued. \u201cThe latter two then help define the head. Knowing the flow and head permits the size of pump and piping to be ascertained. You\u2019ll also need to define the duty condition, which will allow the relationships between fluid velocity, pipe diameter, and friction to be understood.\u201d<\/p>\n\n\n\n

Before purchasing a pump, the mine should also consider whether it already has a suitable pump in its portfolio. But beware: \u201cChoosing the wrong pump may cause pump failure, service disruption and costly repair or replacement, so it is important to carefully consider all factors before investing in a pumping solution,\u201d warned the Xylem expert. If the dewatering need is short term and specialized, the mine might also consider renting a dewatering pump, an option that delivers potentially lower cost of investment and provides access to another layer of service and expertise within the company.<\/p>\n\n\n\n

Albaugh also recommended considering how the pump will be operated and maintained at this early stage, and what back-up might be required in the event the pump malfunctions. \u201cThis step can sometimes be overlooked, but pumps should not be set up and left to run continuously until they give up. This can significantly shorten equipment lifespan and does nothing to support optimal performance, efficiency and associated cost savings. You should also understand how critical the pump is, so you can build a contingency plan, including a redundant back-up system, if necessary.\u201d<\/p>\n\n\n\n

Finally, but \u201cmost importantly,\u201d Albaugh concluded, optimize the dewatering system. \u201cOne of the first steps to ensuring optimum pump performance is to follow the golden rule of pumping operations: the best efficiency point (BEP; Figure 1). Straying too far from a pump\u2019s BEP leads to premature wear, higher energy consumption, increased maintenance requirements, a reduction of overall efficiency and, as a result, more downtime. Unplanned downtime can cost up to 10 times more than routine maintenance.\u201d<\/p>\n\n\n

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Reactive dewatering removes water from existing sumps in the pit, often using a combination of pump technologies. Photo: Sulzer<\/em><\/figcaption><\/figure>\n\n\n

Factors in pump selection <\/strong><\/p>\n\n\n\n

Pump head requirements\u00a0<\/em>
\u201cMine dewatering operations typically have relatively high head requirements based on economic open pit depths,\u201d said Weir Minerals\u2019 Ian Ross. \u201cWhenever possible, single stage applications are desirable because of the reduced rotating equipment maintenance requirements. Therefore, since centrifugal pump head development is largely a function of speed, impeller diameter and impeller vane exit angle \u2013 and as increasing impeller diameter typically also increases pump capital costs \u2013 higher pump speeds are desirable.\u201d<\/p>\n\n\n\n

When open-pit operating depths exceed the discharge head, however, a multi-stage (in-series) system will need to be implemented. These incorporate many of the same principals of a single-stage pumping system, but focus on using multiples of the same pump model to duplicate the flow rates and evenly balance out the discharge head requirements per pump unit. \u201cThis ensures pumping efficiencies are optimized in terms of power requirements, wear rates are minimized and maintenance cycle times maximized,\u201d said Ross. <\/p>\n\n\n\n

Pump impeller diameter<\/em>
\u201cMatching of the pump impeller diameter and, indirectly, the pump torque curve, to the engine is also an important consideration, as running the diesel engine at high loads and below its rated speed results in a \u2018lug\u2019 condition,\u201d said Ross. \u201cLug conditions can result in high exhaust manifold temperatures in turbocharged engines, since they\u2019re not running at their optimum speed and have less air filling the cylinders. This can also lead to higher cylinder temperatures and associated mid- to long-term effects on engine valves, among other things. Additionally, the lower operating speed of cooling fans reduces heat rejection and can be detrimental to the life of the engine.\u201d<\/p>\n\n\n\n

Powering your pump: diesel vs. electric<\/em>
\u201cFlexibility is important in dewatering applications because there are often changing factors that have to be accounted for, such as inclement weather, changes in mine planning, varying pump duties (flow and head), and solids content, among others,\u201d explained Ross. \u201cAs a result, applications are usually diesel-powered mobile units; however, depending on power availability at the site, electrically-powered pumps are also an option. There is also a definite shift towards electrification, as mines consider more environmentally sustainable practices.\u201d<\/p>\n\n\n\n

According to Ross, when it comes to energy consumption and carbon emissions, \u201cthe benefits of electric units are widely understood and acknowledged. This energy efficiency also dramatically reduces operating costs.\u201d Taking Weir Minerals\u2019 range of dewatering pumps as an example, Ross noted that its electric-powered units are about five times less expensive to run because of the difference in the cost of diesel and electricity (subject to regional fluctuation and variation in prices). <\/p>\n\n\n\n

Electric pumps also have a number of other advantages over their diesel counterparts when it comes to maintenance, digitalization, and health and safety. <\/p>\n\n\n\n

\u201cThe maintenance costs for equivalent-sized electric motors are considerably lower,\u201d continued the Weir Minerals expert. \u201cDiesel engines are mechanical, so the wear can be significant, while the maintenance requirements can be onerous. They require ongoing preventative maintenance, which is typically scheduled for every 250 operating hours and includes things like changing the fuel, oil and air filters. With an electric motor, the operator plugs it in and, aside from occasionally lubricating the bearings, it just keeps spinning. Maintenance is, therefore, a fraction of the cost.\u201d<\/p>\n\n\n\n

Electric units also integrate much more easily with remote monitoring technology, said Ross. \u201cIn diesel-powered units, the data that reports on the health of the equipment is collected by sensors. In other words, operators use electrical technology to monitor mechanical equipment. It’s not just simpler to collect this data when the motor is electric, it’s also more accurate and less likely to fail.\u201d<\/p>\n\n\n\n

A final advantage relates to health and safety, as electric engines are substantially quieter than diesel engines. According to Ross, an open-air diesel engine operating at 1800 rpm will generate about 80+ decibels at 5 m. Without hearing protection, this sound level can cause serious auditory injury over a single working day. Comparatively, a four pole 60-Hz electric motor at 1800 rpm produces about 15 decibels at 5 m. This provides a significantly safer working environment and also allows personnel working near or around the operating equipment to communicate easily.<\/p>\n\n\n\n

My water contains solids! <\/em><\/p>\n\n\n\n

\u201cPump selection when solids are present in the water is very much dependant on the particle size, weight and concentration of the solids,\u201d said Xylem\u2019s Albaugh. \u201cThese factors \u2013 along with normal pump selection criteria \u2013 enable you to determine on the correct pump. Slurry pump selections are based on many of these factors to avoid premature wear and failure.\u201d<\/p>\n\n\n\n

\u201cDue to possible solids content and operation at higher speeds, wear performance is important,\u201d agreed Ross. \u201cWe address this in hydraulic design, mechanical design and in materials selection. For example, mine run-off is often both erosive and corrosive, and material selection must consider both. Hardened martensitic stainless steels are a standard offering in Weir Minerals\u2019 Multiflo BSP dewatering pump wetted parts, while various other materials are available depending on the application.\u201d<\/p>\n\n\n\n

The presence of solids may also indicate the need for an agitator in order to \u201cprevent heavier elements from settling at the bottom of the sump and clogging the pump,\u201d said Albaugh. \u201cAgitating the slurry also prevents the solids from becoming too viscous to pump.\u201d <\/p>\n\n\n\n

Agitation is particularly relevant when the dewatering takes place via a batch-style pumping system, added Ross. These involve multiple, external, independent pumps \u2013 usually submersible \u2013 feeding a tank, which is then emptied via the primary pumping system. \u201cWhen the primary pump system is not pumping and the feed tank is in fill mode, solids can settle in the feed tank. In such cases, the addition of an agitator in the feed tank prevents the solids from settling out.\u201d<\/p>\n\n\n

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Common dewatering pump types include submersible pumps, self-priming pumps, end-suction pumps, multistage pumps, and vertical turbine pumps. Pictured: a Sulzer XJ 900 high-capacity dewatering pump. Photo: Sulzer<\/em><\/figcaption><\/figure>\n\n\n

The consequences of poor pump selection\u00a0<\/strong>
\u201cChoosing the wrong pump may cause pump failure, service disruption, and costly repair or replacement, so it\u2019s important to carefully consider all factors before investing in a pumping solution,\u201d explained Xylem\u2019s Ken Albaugh.\u00a0<\/p>\n\n\n\n

For example: <\/p>\n\n\n\n

  • Pumps that are not compatible with the water\u2019s physical or chemical properties can be at risk of premature failure, causing costly, unplanned downtime.<\/li>
  • Older pump hydraulic designs and fixed-speed installations may consume far more energy than the latest premium efficiency units with variable-frequency drives (VFDs).<\/li>
  • Pumps operating outside their optimum efficiency range waste energy and are subject to faster wear and shorter service life.<\/li><\/ul>\n\n\n\n

    The journey doesn\u2019t stop once a pump has been selected and installed, however. Adopting best operating and maintenance practices are vital in achieving optimal performance, while minimizing wear. How then does a mine go about this?<\/p>\n\n\n\n

    Getting the most from your pump <\/strong><\/p>\n\n\n\n

    \u201cA crucial factor is ensuring the pump is running as close as possible to its BEP,\u201d said Albaugh. \u201cThere are some helpful digital technologies that support optimal running. Variable frequency drives, for example, enable a pump to vary performance, in real time, based on the fluctuating need. Remote monitoring and control technologies can provide insight into pump performance without the need to be onsite: a tangible convenience saving resources and time that can be invested in other tasks. Some pumps also feature built-in thermal contacts and leakage sensors that automatically signal an alarm or stop the pump from running, if necessary.\u201d<\/p>\n\n\n\n

    All that said, \u201cregular maintenance cannot and should not be avoided,\u201d continued the Xylem expert. Three types of inspection are recommended: initial, periodic, and overhaul. The pump\u2019s installation, operation and maintenance manual will provide the specific service intervals. The following example is taken from the manual for the Xylem Flygt 5100 pump series.<\/p>\n\n\n\n

    Initial inspection: Within the first year of the pump\u2019s operation, an initial inspection checks the pump condition. It\u2019s also important to check wiring: if the pump is not wired correctly, it runs in reverse, which results in the impeller potentially stripping or a loss in performance. The results of this inspection will determine the ideal intervals for periodical inspection and when a more in-depth overhaul will be required.<\/p>\n\n\n\n

    Periodic inspection: Up to 4,000 hours or annually, whichever comes first. Applies to normal applications and operating conditions at media (liquid) temperatures <40\u00b0C (104\u00b0F). This inspection prevents operational interruptions and machine breakdowns. Any measures required to increase performance and pump efficiency are decided during this inspection. For example, impeller trimming, wear part control and replacement, control of zinc-anodes, and control of the stator. <\/p>\n\n\n\n

    Overhaul: Up to 8,000 hours or every three years, whichever comes first. Applies to normal applications and operating conditions at media (liquid) temperatures <40\u00b0C (104\u00b0F). An overhaul lengthens the operating lifetime of the product. It includes the replacement of key components, as well as measures carried out during a periodic inspection.<\/p>\n\n\n\n

    \n
    \"\"
    Selection of the appropriate pump technology requires an understanding of the application, the characteristics and the properties of the water, and whether the water is clean or dirty. Pictured a Multiflo ME electric self-priming pump. Photo: Weir Minerals<\/figcaption><\/figure>\n\n\n\n
    \"\"
    When a dewatering needs are temporary or specialized, equipment rentals may be the best solution for the customer. Renting equipment can potentially result in a lower cost of investment. Photo: Xylem<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

    Pumps go digital<\/strong><\/p>\n\n\n\n

    Digital solutions \u201coffer breakthrough opportunities to get smart about mine water management,\u201d according to Xylem\u2019s Ken Albaugh. They do so by providing solutions to critical challenges, such as operational efficiency, infrastructure reliability, employee health and safety, and environmental sustainability.<\/p>\n\n\n\n

    \u201cSource water is a precious commodity that will continue to be in demand in the coming decades. On top of that, investors are becoming increasingly focused on how mining companies are managing water,\u201d said Albaugh. \u201cSimilarly, sustainable practices are often at the core of a mine operation\u2019s license to practice and this requirement for sustainability will only increase. As resources diminish and global focus on the environment intensifies, it makes sense to harness the power of smart technology to manage this finite resource as efficiently as possible.\u201d<\/p>\n\n\n\n

    There is a wealth of smart technologies available to increase efficiency, convenience, and reliability, and move overall performance of the dewatering system to the next level. Albaugh cited the example of variable frequency drives (VFDs), which now enable pumps to respond smoothly and efficiently to fluctuations in demand. Motors have also improved greatly in recent years: switching to the latest premium efficiency model can quickly reap dividends in energy savings. <\/p>\n\n\n\n

    Meanwhile, SCADA systems enable remote monitoring and control, eliminating the cost of sending technicians on equipment checking rounds \u201cWith improved visibility, mine operators can better plan their day, be aware of pump failure quickly and eliminate flooded production areas, as necessary,\u201d said the Xylem expert. \u201cEnhanced visibility of pump operations also reduces safety risks, as staff are not required to go on site to check on the pump.\u201d<\/p>\n\n\n\n

    Pumps in the wider water management ecosphere <\/strong><\/p>\n\n\n\n

    Pumps are of course only a part \u2013 albeit a crucial part \u2013 of wider mine water management systems, something that Xylem have picked up in their Holistic Mine Water Management Guide, which notes that: <\/p>\n\n\n\n

    • By 2025, two-thirds of the world\u2019s population could face water-stressed conditions. <\/li>
    • 180 million metric tons of mine waste flow into the world\u2019s waters annually. <\/li>
    • Four billion gallons of water per data are withdrawn for mining purposes, yet water affordability is among the top 10 issues for miners.<\/li><\/ul>\n\n\n\n

      These water-related challenges are complex \u2013 and are exacerbated by growing demands for the mineral commodities that the mining industry provides. When it comes to any aspect of mine water management, \u201ctaking a holistic approach will help ensure a smooth-running and sustainable operation,\u201d concluded Albaugh. \u201cYour bottom line will thank you for it!\u201d<\/p>\n","protected":false},"excerpt":{"rendered":"

      Surface mine dewatering pumps may not be particularly glamorous, but they are essential. North American Mining magazine talked to three experts about the most important factors impacting pump selection and performance. By Jonathan Rowland Dewatering pumps \u201cplay a critical role in all mining operations and are therefore among the most important equipment in a mine,\u201d said Mikael Hjelm, business development…<\/p>\n","protected":false},"author":5,"featured_media":3995,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"om_disable_all_campaigns":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_themeisle_gutenberg_block_has_review":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[4],"tags":[1771,1770,832,532],"coauthors":[1635],"class_list":["post-3994","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-features","tag-electric-pumps","tag-mine-dewatering-pumps","tag-surface-mine","tag-weir-minerals"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t