The global challenge of water stress and scarcity is being exaggerated by growing population, increasing water pollution and rapid economic development in the emerging regional markets. This, according to Frost & Sullivan “is driving the demand for advanced water and wastewater treatment technologies and solutions such as membrane systems, which established a $5.5 billion market size in 2012 and is one of the fastest growing technology segments witnessing double digit growth rates.” The increasing penetration of membrane systems across the water cycle has led to innovative management approaches, the improvement of water supply, treatment, conservation as well as to the much needed rise in reuse and recycling water. Membrane systems are discussed in a separate article in this issue by Tim Lilley of Pall Corp.

Frost & Sullivan research analyst Paulina Szyplinska said: “Overall, the global membrane water and wastewater treatment market is expected to experience significant growth in this decade, driven by the ongoing focus on high quality drinking and demand for high purity process water in water intensive and critical sectors”.

The prospects for membrane technologies, including microfiltration, ultrafiltraton, nanofiltration and reverse osmosis, are ‘hot’.  Let us begin with news of an innovation to reduce underground mines’ use of water.  Atlas Copco has a new dry drilling system available on its Boomer XE3 C drill jumbos. “For the first time,” the company says it “is able to deliver a three-boom face drilling rig that is totally waterfree.”  Compressed air is used to keep the hole free from cuttings and a suction nozzle around the drill string eliminates dust. The suction hose then returns the dust to a filter unit and a sealed container for simple dust logistics. Atlas Copco says the “system is ideal for projects where water is scarce or where it’s not possible to use water due to rock conditions or surrounding temperatures.”

Fresh water usage at Xstrata Copper’s Mount Isa Mines copper concentrator in Australia was reduced by 40% last year through a series of initiatives, implying a saving of about 800 million litres, in an area where water is a scarce resource.  Richard Harvey, Mount Isa Mines Copper Concentrator Manager notes a number of initiatives implemented in the concentrator to reduce water usage. “These measures included automated daily reports to track water use in all plant areas during the previous 24 hours and setting targets for the flow rate of water used in the operation of our large slurry pumps.”

Further significant reductions were achieved by recycling the water used to cool the ball mill as water for the pumps and installing flow control valves at the wet fill plant.  As well as reducing the impact of the plant on the surrounding environment, the measures have also accrued annual savings of around A$1.1 million.

Reducing liquid waste

There is a multitude of clean-water regulations that can seriously impact business. Strict standards governing discharge into waterways can increase costs and inhibit production. Veolia Water Solutions & Technologies is addressing these issues through advanced treatment processes that allow companies to generate clean water for reuse or environmental discharge with no substantial liquid waste.

Called the Zero Liquid Waste (ZLW) approach, its industrial water desalination technology helps the industry contend with stringent new regulatory requirements that limit the discharge of chlorides and sulphates into streams, rivers, lakes and other bodies of water. Mitigating the effect of such byproduct discharges “on the environment is crucial to the mining company’s ability to produce cost-efficient energy,” Veolia says.

“The Zero Liquid Waste approach is a big step forward for industries seeking to meet challenging new environmental regulations in a cost-effective manner,” said Robert Zick, Mining Market Director of Veolia Water Solutions & Technologies North America. “Mining and energy companies are turning to us for innovative solutions to their water quality needs.”

ZLW features state-of-the-art membrane treatment to achieve discharge criteria, as well as Veolia’s HPD® evaporation and crystallisation technology to manage the brine from the water treatment process. The desalination system creates clean water for discharge while generating zero liquid waste. The resulting desalinated water can be used for various energyproduction endeavours or discharged back into waterways, with the highquality water benefiting downstream users.

It consists of a rawwater pretreatment system, reverse osmosis (RO) membrane system, brine management system and ancillary support systems. 

The raw-water pretreatment system involves pumping water into a raw-feed water tank with a jet mixing grid to prevent solids from settling.  From there, the water enters the first of two aeration tanks that promote the precipitation of dissolved metals, such as manganese and iron, then into a crystallization tank where chemical softening takes place to reduce alkalinity and hardness. Veolia’s MULTIFLO™ softening process provides a small footprint option for this treatment step. The MULTIFLO system combines softening and clarification by including the company’s Turbomix™ technology, which provides thorough draft-tube mixing to minimise chemical use and promote formation of a crystalline sludge that is easily dewatered in a filter press.  The water is then conveyed to an aluminium precipitation tank where acid is added to neutralise the water’s pH level and precipitate dissolved aluminium for removal in the subsequent filtration step. The aluminium precipitation tank overflows into an adjacent multimedia filter feed tank and is pumped through vertical multimedia filters to remove residual suspended solids.

The single-pass, three-stage reverse osmosis (RO) system performs desalination in the ZLW water treatment process. The RO system itself consists of parallel skids, each containing multiple stages of RO pressure vessels comprising each skid. Before entering the RO system, water goes through a cartridge filtration system which removes any fine colloidal particles. The clean permeate water from the RO system – minus the majority of the chlorides, sulphates and other dissolved solids contained in the feed water – goes to a product water tank where it combines with distillate from the evaporation/crystallization process. Minerals are then added to the water to protect aquatic life before it is discharged into waterways.

Without the brine management system, the approach couldn’t achieve Zero Liquid Waste.  Reject from the RO system is concentrated brine containing the dissolved solids and other constituents removed from the feed water. The brine is sent to a separate MULTIFLO™ softening system to remove the calcium and magnesium hardness prior to being sent to a thermal treatment process consisting of an HPD® evaporator and crystalliser.  The HPD evaporator concentrates the RO reject by removing the majority of the water in an energy-efficient and economical manner.  The evaporator and crystalliser typically utilises a mechanical vapor recompression system that compresses the vapors created by concentrating the feed brine and then recycles the vapors back into the heater shell to provide a heat source for the evaporation process. Depending upon the relative cost and availability of natural gas and power, the crystalliser may be driven directly with low pressure steam from a natural gas boiler in lieu of using mechanical vapor recompression. The high-solids brine from the evaporator goes to the crystalliser feed tank and is pumped to the crystalliser for further concentration. As the evaporation process continues, the concentration of the brine increases, and as that happens, the solution becomes supersaturated and salts precipitate from the solution, resulting in a highly concentrated brine slurry. Centrifuges are used to dewater the brine slurry, creating a non-hazardous solid waste containing no free water, facilitating landfill disposal.

Ancillary systems include chemical storage and feed systems, a lime water preparation system used for remineralisation, a clean-in-place system for the RO membranes and a compressed air system. 

Both the solid waste from the centrifuges and the dewatered sludge generated from the two softening processes pass the paint filter test to meet landfill requirements.  This means no liquid waste leaves the client’s property. In addition, the discharged water improves the quality of water in the receiving stream, a major environmental benefit.

The ZLW approach is available through Design-Build and Design-Build-Operate contracts. When operations are included with the agreement, the process guarantee is extended through the life of the operating contract.  This, Veolia says, “ensures operational efficiencies, including high system availability, long-term operational life and minimal downtime for maintenance, among other advantages. More importantly, the system promotes responsible environmental stewardship and sets a new standard for water treatment in the industry.”

Two Canadian companies, BioteQ Environmental Technologies and Newalta Corp, have jointly developed a mobile Sulf-IX™ pilot plant to provide on-site field testing for sulphate removal from a wide range of industrial waste streams. The partnership combines the strengths of BioteQ as an innovative developer of wastewater treatment technologies and the operational and safety know-how of Newalta to deliver a system to test small volume, low-flow effluent to demonstrate the applicability of Sulf- IX to remove sulphate.

With a capacity of 14.4 m3/d, the pilot plant applies BioteQ’s ion exchange based Sulf-IX technology. The process produces treated effluent with low residual sulphate concentrations for re-use or discharge. Up to 99% of the wastewater can be recovered for reuse and the only byproduct of the process is a solid gypsum product.

BioteQ says “treatment of acid rock drainage (ARD) has primarily focused on acidity and dissolved metals due to its toxicity to the environment and human health. Less attention has been paid to sulphate, despite the high concentrations that have been recorded at some sites. Sulphate is a common sulphur compound found in many industrial wastewater sources.”

“For humans, the taste thresholds for sulphates range from 250 to 500 mg/litre and drinking water containing sulphate levels in excess of 600 mg/litre can have laxative effects.  In industrial operations sulphate can interfere with operational efficiency by causing scaling of process equipment, leading to premature equipment failure and higher maintenance costs.

“Growing awareness of the impact of sulphate is leading to increased scrutiny and regulation for sulphate discharge limits in many jurisdictions around the world. Depending on the receiving water, sulphate discharge limits have ranged from a maximum of 2,000 mg/litre for surface water discharge in Chile to 10 mg/litre in the US State of Minnesota.”

Wastewater treatment is a considerable and essential investment for any mine operation, with each site having its own unique treatment requirements. The mobile Sulf-IX pilot plant allows for on-site testing and verification to be conducted on actual process effluent. The testing program consists of a series of test runs at various operating parameters to validate process performance and operating costs. Data collected from the pilot plant testing is used to generate the design criteria for a full-scale facility.

Water and chemical mass balance

MWH’s Zygi Zurakowski (Geotechnical Engineer) and Resa Furey (Market Analyst) contend “there is no simple recipe for managing water at a mine, integrating the skill sets of engineering and science disciplines is an important ingredient. Site-wide mine water balance models are a standard, and valuable, approach to managing and accounting for volumes of water, in, out and throughout a mine. Including aspects such as water quality data to the water balance framework creates a powerful management and strategic planning tool that can be used to evaluate the impact of environmental and operational changes as well as uncertainties at a mine site. Combining the expertise of the various engineering disciplines including the hydrological, geotechnical, geochemical, environmental and water treatment engineers into a single water management tool will contribute to a mine’s success and regulatory compliance.

“The need to couple chemical mass data with water balances is driven most often by two factors: first, impacted mine water discharged to the environment must meet regulatory water quality standards. Second, recycling water within the mine may impact (positively or negatively) mineral recovery, so tracking and forecasting of the water chemistry is crucial.

“Effectively-developed Water Balance (WB)/Chemical Mass Balance (CMB) models track chemical concentrations and monitor water flows throughout the mine; they can evaluate whether treatment is necessary prior to discharge to the receiving environment, and if so, what the treatment system influent concentrations are which will subsequently effect treatment system design criteria. In addition, the combined models help operators understand the effects of recirculating chemical loads: on long-term treatment requirements, and process water quality. Importantly, these models can also be used to demonstrate if treatment systems can reliably meet discharge requirements. As regulations continue to target mining effluent, and requirements become stricter, savvy tools help operators and managers make improved decisions.

“CMBs are most often completed during design and evaluation of individual operational components such as waste storage facilities, heap leach pads, etc., and are often not considered in context of how the flows and chemical loads will impact processes throughout the mine. To combat this, the chemical mass data from the different mine components should be coupled with a site-wide water balance model early in the mine planning, and as the mine plan is updated, so too should the combined model.

At a Latin American mine with challenging water management conditions, MWH engineers led a team to complete a combined WB/CMB tool. This was used to provide data for sustaining capital investments, water treatment process decisions and environmental compliance that would result from the addition of a leaching circuit to a mine with an existing grinding circuit and tailing storage facility. The model helped to evaluate the following scenarios: a) how operational changes would affect the chemical make-up of the water reporting to a proposed water treatment plant, b) the efficacy of the treatment plant, c) the composition of the treated effluent, and d) how water recycling would affect mineral recovery.  Because the operators wanted to discharge a waste stream from one area of the site into the tailing storage facility, the combined model showed that chemical concentrations in the tailing reclaim water would be extremely high and have a very negative impact on mineral recovery. Through the use of the combined WB/CMB model, it was possible to discern acceptable chemical concentrations for both discharge to the environment and recirculation within the mine. Based on the collaboration between the various engineering disciplines, the team could provide water treatment and management recommendations which optimised both cost and mineral recovery.

In Australia, a mine was looking to dispose of water treatment plant sludge on-site. By using a WB/CMB tool, engineers were able to determine whether or not the sludge would remain stable and potentially leach if disposed at the bottom of the pit. The combined model provided data to help determine whether this disposal method was feasible and whether or not it would result in significant cost savings. This determination would not have been possible without the combination of geochemical and water balance modelling. The coupled model provided an understanding of the best method to dispose of the sludge and whether or not the metals would re-dissolve and require they be routed to the water treatment plant.

At a precious metal mine in Eastern Europe a cyanide mass balance was completed in conjunction with the water balance to fulfill regulatory requirements for permitting. One use of this model was to track the movement of cyanide throughout the operation. Going beyond the routine permitting requirement and the typical level of detail required, the combined WB/CMB model traced the cyanide from cradleto- grave in a predictive manner that accounted for consumptive use and chemical transformations. For example, the model addressed the fate of cyanide in the tailing impoundment including HCN volatilisation from the reclaim pond and attenuation of cyanide during seepage through the embankment foundation. Cyanide concentrations during both operations and closure were forecast. The WB/CMB also helped to improve the accuracy in air quality modelling by defining the source terms. Ultimately, the WB/CMB helped reduce reviewer concerns regarding the use of cyanide at the mine.

Finally, at a closed U.S.-based copper mine, a WB/CMB and groundwater model was completed to evaluate the potential range of volume and quality of seepage from waste piles through a proposed seepage barrier wall. The combined tool was used to evaluate mixing different water flows at the site to get a more favourable influent composition for treatment.  Based on results from the model, a pilot test program was developed. This process allowed MWH engineers to identify that one single treatment plant would achieve better quality effluent than the two treatment plants that were originally planned. Combining the impacted streams identified optimised process conditions; this simultaneously enhances the ability of the treatment plant to meet stringent discharge criteria and reduces operating requirements, both translating to cost savings.

Treating tailings

Blue Gold has been designing and building a solution to recover platinum, gold, silver, uranium, and other precious metals with its patent pending LAREMUTEC (Laser Aided Methodology with Ultrasonic and Thermo-Electric Conductivity) process, while simultaneously using this technology to rid the water used in the mining process of any contaminants including toxins such as cyanide.

After initial consultations with clients, Blue Gold performs a detailed analysis of both solid and liquid samples to determine the most efficient design solution using Blue Gold proprietary technology to build the application to suit client requirements. A final assessment including proposed costs and Blue Gold proprietary technology requirements is provided to the client. Once the client approves the solution a long term contract for water purification and/or precious metal recovery is executed. The first Blue Gold LAREMUTEC plant is currently in production and will be installed this year.

The process starts from the pond mine tailings or directly from the tailings tank, where a slurry pump transports the liquid into a hydrocyclone and it passes through electronic precipitators where heavier and lighter solids and water are separated and suspended solids and metals are removed. Contaminated water then passes through the Ultrasonic Diffused/Dissolved Air Flotation (UDAF) process where micro bubbles produced by sonic waves breakdown the solution thus releasing free water molecules. Heavy sludge that settles in the bottom of the tank and lighter sludge that floats to the top are both removed. Collected water from the sludge concentrator flows to a smaller electrolysis unit to capture the remaining dissolved metals.  The water discharged from the UDAF is then put through a centrifugal separator where remaining particles are separated and then polishing starts at the media filters. Final filtration occurs at the nanofilter where sub-micron particles and other volatile organic compounds that were not removed previously are collected. Polished water discharged from the nanofilter is then sent to the Ozonator for oxidising and disinfecting remaining pollutants, and once water is discharged and regional standards are met, water is stored at the final clarifier tank for distribution. If standards are not met at this tank, a diverter valve redirects the water back to the system for reprocessing.

The system is not only focused on wastewater treatment, but also on recovering dissolved precious metals. This is achieved by augmenting the use of other Blue Gold technologies that are applied in the ion exchange using Blue Gold Nano Resin. This particular nanoresin, will absorb the dissolved precious metals. The resulting material can be sent to refiners for the extraction of the adsorbed metals. Laboratory tests have shown the efficiency of this technology is around 70%, however fine tuning in the field is required to confirm this efficiency.  Due to the complex nature of the environmental factors of a specific project, the cost per cubic meter of the tailings needs to be evaluated on a case by case basis.

Stricter discharge limits

Tom Sandy, Michael Blois, and Marek Mierzejewski of CH2M Hill note “the management and treatment of waters for target pollutant and/or water quality parameters (e.g., heavy metals, acid mine drainage, scaling elements) has been a long-standing challenge in the mining sector, whether from active or closed mines. Relatively straightforward treatment through a variety of active and passive treatment processes has been successfully used over the years for simple pH neutralisation and heavy metals precipitation utilising a variety of alkaline agents. However, discharge requirements for both heavy metals and other water quality parameters have become more stringent and comprehensive. This includes heavy metals being regulated to nearly the method detection limit as well as the addition of other water quality constituents of interest (e.g., selenium, sulphates, chlorides, TDS, osmotic pressure (OP), conductivity, etc.).”

Treatment of both heavy metals to lower levels and other water quality constituents of interest require different and more sophisticated water management and treatment approaches to maximise benefits and minimise costs.  There are a variety of water treatment and brine management technologies in various states of readiness to meet these requirements, with some more or less selective for constituents of concern. These CH2M Hill practitioners list:

■ Membrane base (e.g., Reverse Osmosis (RO), Nanofiltration (NF), Ultrafiltration (UF), Electrodialysis Reversal (EDR), Electrodialysis (ED) et al.)

■ Ion exchange (IX) (e.g., weak and strong base/acid polymeric resins, liquid extractants, adsorption media)

■ Chemical treatment (e.g., zero valent iron precipitation methods for sulphate and TDS)

■ Active biological treatment (e.g., anoxic/anaerobic attached and suspended growth biochemical reduction processes

■ Passive biological treatment (e.g., vertical flow biochemical reactors and horizontal flow wetlands).

“In cases where specific water quality parameters (e.g., selenium, cadmium, sulphate) are only targeted versus a broader range of water quality parameters (e.g., osmotic pressure, conductivity, osmotic pressure), the challenge is finding technologies that are specific to the constituent of interest. CH2M Hill has found that it is more cost effective to find treatment technologies (e.g., IX, chemical, biological) that are water quality parameterspecific versus technologies (e.g., RO, NF, EDR) that treat a broader range of parameters, given brine and residuals management issues.  However, when this is not possible given the water quality criteria for factors like TDS, conductivity and OP, or there is a high potential for future more comprehensive water quality criteria for these same parameters, then more non-selective treatment technologies will inevitably need to be considered. Each of these water treatment technologies will require brine and/or residuals management and disposal technologies (e.g., thermal evaporation/crystallisation, thickening, and dewatering). Depending upon the selectivity, brine management and reconstitution may be potentially bigger issues than the water treatment itself.

“Careful consideration of these treatment and residuals management aspects must go into determining a water management strategy, and methods for equalisation and diversion of surface and subsurface water discharges are key to minimising treatment requirements and costs. In particular, management of wet weather flows (e.g., storm water, snow melt) requires special consideration. CH2M Hill has found that water resource management tools are needed to predict water quantities and determine effective water management approaches such as subsurface mine storage, end pit storage and rock dump diversions. This information coupled with water quality monitoring data to develop material mass balances is key in determining both water management and treatment requirements. CH2M Hill has developed a variety of water resource, material mass balance and predictive water chemistry tools to optimise a mine site’s water envelope to improve the decision making about ultimate water treatment processes.”

For instance, CH2M Hill used Voyage™ to model a cost-effective water management system design to achieve compliance with selenium limits at a North American surface/underground operation. The model was used because of its ability to estimate a longterm chain of events in series that depends on the storage volumes of ponds, the quantity of flow conveyed into the underground mine, the estimated infiltration into the underground mine, the mine’s storage capacity, and the proposed pumping scheme. CH2M Hill conducted modelling based upon a series of assumptions (infiltration rate into the mine, hydrologic prediction of flow rates from the consent decree outlets, selenium concentration in the outlets and in the infiltration water) that the projected discharge into the underground mine and conveyance to the river under increased site specific selenium discharge limits would achieve long-term compliance. The construction of selenium removal treatment plants was thereby avoided.

They conclude that “overall, the industry needs to be aware that the trend of being required to meet more stringent water quality criteria requires a higher level of water treatment and focus on the brine management reconstitute issue, demanding more sophisticated water management strategies to minimise the cost of that treatment.”

Economic byproduct recovery

At the SME Annual Meeting this February in Denver, K. Tabra and O. Gaete of Arcadis presented ‘Ways to deal with mine/plant effluent residues: a roadmap process’.  They concluded that “chemical precipitation is a well-accepted technology which offers a solution for metal removal requirements and achieves stringent discharge limits that are protective of public health and the environment.  It is a flexible technology that can address metal contamination in waste water at mine sites. This technology can be used in conjunction with other treatments or by itself, depending on effluent characteristics and treatment target. Its immediate results, efficiency, easy implementation and monitoring are the main advantages. However, the active nature of the process (use of chemical reagents), energy inputs, operation and maintenance can lead to relatively high treatment cost.

“The proposed Roadmap is an effective tool to address the challenges of mine waste water active treatment and to evaluate the possible recovery of valuable elements. It consists of a first stage of diagnosis and optimisation of the system in order to reduce water make up and improve effluent quality. A second stage of characterisation is needed to define treatment targets based on local standards and historical information. The proposed treatment is defined by laboratory tests on waste water samples.  These tests determine reagent consumptions, design parameters and a first approach to the costs required for treatment alternatives and possible recovery of valuable elements.  Economic and efficiency analysis of different alternatives dictate the chosen treatment. 

“In general terms, lime technology has lower treatment costs at the expense of voluminous contaminated sludge generation. Precipitation with sulphides or co-precipitation with ferric chloride allows a more effective and controlled removal of contaminants and their possible recovery for commercial purposes. Also, by these means the volume of sludge generated is considerably smaller.

“The recovery of byproducts from mineral waste water is a promising approach from a technical, economic and environmental point of view.  This recovery can account for a portion of the treatment cost and in some cases generate profits. However, detailed laboratory investigations should be carried out to correctly evaluate the economic and environmental feasibility and benefits.”

Magpie Polymers has an innovative and patented filtration technology for the selective removal of transition metals from industrial waste or process water. Its technology gives a high-performance and simple to apply solution to the increasing problem of metals in water. It can be used for toxic metal removal but is best suited for the recovery of precious metal.

The company, a spin-off from the French Institute Ecole Polytechnique, produces different polymers to capture a large number of metals including platinum, palladium and gold or even cadmium and uranium, leaving less than a mg/m3 of metal in water.  Magpie also recovers the captured metals, specifically the increasingly scarce and valuable metals.

 Magpie’s Polymers fix metals in a standard filtration process, using co-ordination chemistry.  Selective bonds are formed between the metals and the polymer beads. This is very different from ion-exchange chemistry, commonly used in water treatment, giving Magpie, it says, “improved performance and improved selectivity:

■  Extremely selective for target metals only (despite 1,000 x or more common metals, salt)

■  Operates in difficult conditions (low pH, oxidising, high TOC)

■  High performance (low residual metal concentration)

Pumping iron

Weir Minerals Multiflo® pumps are continually pumping excess water, keeping pits dry, enabling continuous production. The company notes that “almost all mines will experience dewatering situations within their operations from ingress of water from above and below. “

“Established in 1978, Multiflo mine dewatering pumps are engineered with over 30 years of industry knowledge and experience.  A dedicated research and development department works closely with our dewatering system team and customers to engineer innovative solutions to suit the market needs.  We are constantly striving to create:

■  Safer working conditions for employees in mining

■  Shorter lead times 

■  Higher quality products 

■  Lower production and operating cost 

■  More efficient use of space 

■  Lower total ownership cost

One particular model, the MF – 90V diesel driven pump unit can operate across almost the entire curve, capable of a maximum shut off head of 110 m with maximum flow of 420 litres/s. It is able to operate in most arduous conditions including corrosive slurries of sulphuric and nitric solutions to a Ph level of 3.

The MF-210MV high head pump supplements the requirements at some operations for two pumps to achieve this duty. From the curve, the MF – 210MV Diesel driven pump unit can operate across almost all of the curve, capable of a maximum shut off head of of 210 m with maximum flow of 170 litres/s.

The materials build for the MF-210MV allows this pump to operate in most arduous conditions including corrosive slurries of sulphuric and nitric solutions to a Ph level of 3.  Weir Minerals says its “Multiflo pump units can be custom-built to suit any mine-specific application, ensuring top performance for mine operations. [The] pumps have been built using corrosion and wear-resistant materials so they work within the harshest environments on earth as well as in increasingly unpredictable weather patterns.

Continuing its investment in the development of a range of super silenced pumps, Sykes Pumps has launched its new MH150/100 Super Wispaset. Applications include any situation where high vertical and/or long discharge runs are required. The company says “the new MH150/100 Super Wispaset raises the bar in terms of low-noise pumping without compromising on power, reliability and flexibility. Employing a 129 kW Iveco engine, the unit is capable of heads up to 105 m, with a maximum flow rate of 320 m3/h (or 89 l/s) and noise levels down to an average of 70 dBA at 7m. The pump is set to run at 1,800 rpm which means that fuel costs can be lower and engine noise reduced. In fact, when operating at Best Efficiency Point, the fuel consumption is an economical 21 litres/h. Despite being aimed at applications where there is a low concentration of solids, the unit has a credible solids handling capacity of 20 mm spherical.”

Other key features:

■  Automatic control panel & optional Telemetry facilities – providing remote monitoring and management, which can highlight issues often before the user is aware

■  broad curve producting high flows at most heads

■  Robust chassis for use in demanding environments and rugged terrains.

■  Super silenced canopy with access to all areas for ease of maintenance.

Sykes Pumps’ Chris Graham, Pump Development Director, explained: “For a number of years now, we’ve made a very deliberate effort in bringing new pumps to the market that have a clear focus on sound attenuation, durability and fuel economy. It has been possible to develop this new Wispaset pump by understanding the very unique needs our clients have in extremely demanding industries and market sectors. Our new MH150/100 pumps ensure clients do not have to choose between productivity, efficiency and having an environmental conscience.”

Xylem launched powerful new dewatering pumps under its Flygt and Godwin brands at Bauma in Munich, in April. It unveilled a new series of submersible dewatering pumps modelled on its popular Flygt BIBO pump. The company also introduced a powerful and compact Godwin pump specifically designed for lower head dewatering applications.

“Demanding conditions on a site and a changed business environment where resources are limited mean that customers need ever more reliable and durable technologies, and we are responding to that need with some smart new dewatering solutions,” said Andrew Jones, head of Xylem’s dewatering business. “We believe the new Flygt BIBO will make a big impression, as well as within the construction and mining sectors when launched globally later this year. We will also launch our new Godwin Vac-Prime, a highly efficient, automatic self-priming dewatering solution ideally suited to well-pointing. It features Godwin’s trademark reliability and high performance in a compact, lightweight model.”

The new Flygt BIBO range incorporates several proven design features taken from the original dewatering pump, as well as innovative enhancements that give the new pumps better wear resistance and uptime capability. Durable and robust, the new BIBO series has been specifically designed for the toughest dewatering environments including mining.  More than one million of the original Flygt BIBO pumps have been sold since they were introduced in the 1960s.

Godwin’s extensive range of Dri-Prime pumps for medium- to high-head applications is now joined by the Godwin Vac-Prime which has been specifically designed for lower-head dewatering jobs. As a result of its compact size, the Vac-Prime is easy to move and transport. It does not require specialist transport and with its lifting frame, fork pockets and optional wheels, it needs minimal on-site equipment. The speed of air evacuation that it delivers is due to a combination of the highly efficient vacuum pump and the fast-priming system. It is light and small in size but has, Godwin says, its “trademark reliability and robustness at its core.”

Xylem has enhanced its Flygt 2600 drainage pump series making it even more reliable and durable, ideal for use in tough dewatering conditions and applications. “The Flygt 2600 drainage pumps are at least three times more wear-resistant than conventional drainage pumps,” according to Flygt’s 100-hour wear test.” New enhancements to the range include increased durability of the seal system, greater protection against corrosion, a simplified design and enhanced capability for dry running.

Featuring non-clog Flygt N-technology, Xylem’s Godwin NC-Series is engineered to deliver clog-free pumping for maximum uptime and effectiveness. In wastewater pumping applications, fibre and stringy solids can cause difficulties. Pumps can often clog, requiring maintenance and resulting in unplanned downtime. Xylem’s engineering teams have integrated Flygt N-technology into the Godwin Dri-Prime range to create this non-clog feature that is ideally suited for a multitude of applications in mining.

A team of Tsurumi pumps are essential to one of Europe’s copper open-pits. Operated by Hellenic Copper Mines, the 4,000 year old Skouriotissa copper mine in Cyprus is one of the oldest mines in the world. Integral to the day-today operation of the mine, the pumps remove groundwater, rainwater and highly acidic liquids (pH 2) seeping into the pit. The pumps are working fault-free at the site.

Skouriotissa has tried several submersible pumps over the years, with some proving more successful than others. Tsurumi pumps have worked in this challenging environment for more than two years. The first Tsurumi pump was installed at the site in 2011, and all have been working fault-free since then.

The Tsurumi pumps are mobile units that are moved around the site to wherever they are needed. They include models from Tsurumi’s SFQ range, which are specially developed for corrosive liquids and made from austenitic steel – and the PU range, which is made from stainless steel and high-tech resin moulds making it durable and light-weight. The PU pumps are around half the weight of an equivalent conventional pump, so they are easier to move around sites. Hellenic Copper Mines notes that all of the pumps perform especially well when continuously used to pump muddy water, even when the water level drops to a minimal amount.

Occasionally, mud builds up on the suction cover causing a small blockage but this is easily removed thanks to the design of the Tsurumi pumps, which allow for quick and easy disassembly for cleaning by any on site worker.  In fact, the design of the pumps mean they can be completely dismantled in as little as eight minutes.

Cornell pump company has had a lot of success in mining. For instance, some years ago, 16NHG22 Redi-Prime® pumps moved 9,842 million litres of water in just seven weeks when the Diavik diamond mine was first developed in the Canadian Far North.  The kimberlite pipes were located about 12 m beneath Lac de Gras in the Northern Territories.  To recover the diamonds, dike walls were constructed around the diamondiferous pipes and the water entrapped behind the dike was pumped out.

A fleet of eight Cornell 16NHG22s were employed on two barges. Pumping more than 1.4 million litres per minute around the clock for 49 days, the pumps worked extremely hard in harsh conditions, operating just 200 km south of the Arctic Circle.

Cornell reports that “without the ability to successfully move that much water, that quickly, and without breakdown, the mine might have been delayed more than six months in its opening.” Cornell pumps are now used in the underground phase of the mine.

Chris Rehmann, Mining Business Manager, AESSEAL, explains that “packing has several drawbacks when used to seal rotating shafts on pumps. Perhaps the biggest drawback is the requirement for millions of gallons of gland water per pump per year, for cooling and lubricating the packing.

“Double mechanical seals and tank systems eliminate all of the problems associated with packing and can greatly reduce a mine’s water footprint, while also reducing the manpower required to care for the packing and increasing the uptime/availability of the equipment. In those cases where the process is sensitive to dilution, double mechanical seals can save millions of dollars per year in lost product.

“Not just any mechanical seal arrangement will accomplish the above goals. The pump owner must select a robust double mechanical seal and then maintain a clean, stable fluid film across the seal faces. This is accomplished by the use of a self-filling, maintenance-free tank support system which maintains the seal barrier fluid pressure at 1 to 2 bar (15 to 30 psi) over the pump fluid pressure.”

Desalination

Powered by GE Technology, Australia’s largest desalination plant came on stream late last year, helping to solve local fresh water shortages.  This plant can supply 150 billion litres of fresh water every year. The plant is among the largest reverse osmosis plants in the world. It was brought online in November 2012, completed successfully the required 30-day continuous production test and reached full operation in December, three years after construction began.

“The expertise of Degrémont in reverse osmosis technology and operations is illustrated through achieving such a rapid, incident-free commissioning phase for a project of this scale, with the milestone marking the beginning of the operational phase. We take great pride in our ability to operate such critical water infrastructure assets around the world. Our operation team, involved in the project since the beginning of the construction phase, is now ready to manage this world-class desalination plant for decades to come,” explained Rémi Lantier, CEO of Degrémont.

“GE’s success on the Victorian Desalination Project stems from its outstanding experience in design and build of motors and drives and expertise in the overall grid system study and filter design,” says Pascal Cros, GM General Industry. “The project enhances the company’s reputation as a worldwide leader in the design and manufacture of low- and medium-voltage electrical systems for the fast-growing desalination industry. It brings another reference to GE in the water industry, where it intends to further develop its presence across a range of industry applications including wastewater, water treatment and transport.”

GE’s Power Conversion business designed and supplied a complete set of medium-voltage motors and low- and medium voltage variable frequency drives, including associated filters and transformers for use in both the reverse osmosis plant and the associated pipeline network. The use of variable speed drives rather than fixed speed motors enables the plant operator to smooth start and stop of the pumps, prevent the water hammer effect, improve control of the water flow and make energy savings. GE furthermore provided on-site supervision and commissioning.

The problem with current desalination plants is the higher power costs. Current filters use plastic polymers that require an immense amount of energy (55 to 70 bar of pressure) to push water through. Lockheed Martin says it has developed a special material that doesn’t need as much energy to drag water through the filter.  In addition, the film is super thin — just a single atom thick — so that the water passes through relatively easily and leaves the salt behind.

Lockheed Martin has been awarded a patent for Perforene™, this special grapheme-based material. The Perforene material works by removing sodium, chlorine and other ions from sea water and other sources.  The Perforene membrane was developed by placing holes that are one nanometer or less in a graphene membrane. These holes are small enough to trap the ions while dramatically improving the flow-through of water molecules, reducing clogging and pressure on the membrane.

At only one atom thick, graphene is both strong and durable, making it more effective at sea water desalination at a fraction of the cost of industry-standard reverse osmosis systems.  In addition to desalination, the Perforene membrane can be tailored to other applications, including capturing minerals, through the selection of the size of hole placed in the material to filter or capture a specific size particle of interest. Lockheed Martin has also been developing processes that will allow thematerial to be produced at scale.

Drinking water

Just like lodging and food, drinking water supply can be a major challenge for mine camps. A leader in the design of custom designed water treatment systems, H2O Innovation says it “is well-known for its expertise in membrane filtration technologies and containerised systems. The drinking water production solutions offered by H2O Innovation to the industry are flexible, adapted to their needs and easy to use in remote regions.”

As part of the installation of a workers’ camp on behalf of Canadian Royalties in Deception Bay, H2O Innovation was given a mandate by Outland Camps to assemble and deliver two insulated and heated 12.2 m containers: the first one being used to recover the lake’s raw water and to contain the membrane filtration sequence, and the second one to store and distribute drinking water. These containers can cover the drinking water needs of a hundred workers, by supplying 20,000 litres of water per day.

Fully aware of major functional, climatic and environmental requirements, H2O Innovation says it “offers its clients handy and reliable solutions, with the following benefits:

■  Constant quality of produced water: Whatever the raw water parameters, the nanofiltration physical barrier removes from water all undesirable substances (contaminants)

■  Mobility:  Containers are easy to move to other sites depending on needs

■  Adaptability:  The treatment sequences easily adapts to the various natures of surface water (lakes, rivers, etc.) and can also be used to treat some types of groundwater

■  Easy maintenance and operation:  H2O Innovation’s treatment sequence requires minimal intervention from the operator 

■  No dangerous chemicals:  The membrane technology used by H2O Innovation ensures a  safe filtration. Discharged water can be sent to storm sewer – with the exception of water resulting from membrane cleaning. In order to remedy this problem, H2O Innovation rotates membrane and cleans them at its plant, which reduces on-site water management requirements and avoids the use of sanitary sewer.

“It is a proven technology. To produce drinking water for workers’ camps, H2O Innovation uses its ‘NanH2Ofiltration’ technology, which is identical to the technology used for municipal systems. This technology has been qualified as proven by the Québec Drinking Water Treatment Technologies Comity (CTTEP), which is authorised by the Ministère du Développement durable, de l’Environnement et des Parcs (MDDEP) of Québec.

“The equipment used in the treatment sequence is assembled and tested in an ideally controlled environment at H2O Innovation’s plant in Ham-Nord, Québec. H2O Innovation can thus offer better manufacturing lead times and can easily adjust if needed.”

IM