int newsletter april-june web

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Intech Engineers recently installed andcommissioned 2 self-priming pumps at theCST Lady Annie heap leach projectin North Queensland.

This was the final element in the stage

3 expansion providing over 200,000m²of leach pads and a nameplate 30,000tpa copper cathode capacity for the SolventExtraction and Electro-Winning (SX/EW) plant.

The pumps transfer leach liquor from theprocess ponds at the heap leach to theprocessing plant and are equipped with a self-priming mechanism. This means that operatorattendance is not obligatory and fully automaticoperation is possible.

PLC programming and HMI interface pages

were completed by Travis Moore, adoptingsimilar control functionality and providingcommonality with existing programs.

Intech’s commissioning team consisted of TomShearer and Travis Moore who worked withsite personnel to make program changes andto ensure interlocks and control functionality.

Pump performance was tested duringcommissioning at a range of operating dutieswhich ensured alignment with design criteriaand functional specifications were met.

Intech reached a milestone with the completionof our first Feasibility Study for a project inChile, South America.

The study included a 2.5Mtpa SX/EWcircuit to process a copper oxide deposit.

Intech were selected to perform the work dueto experience in similar projects for clients suchas CST Lady Annie.

The plant scope includes three-stage crushing,agglomeration, stacking, acid heap leaching,solvent extraction and electrowinning, reagentsstorage and plant services. Plant infrastructurewill include roads and drainage, haul roads,process ponds, stormwater and event ponds,and the construction of Run Of Mine (ROM)and leach pads.

Intech’s scope was to complete concept designcapital cost estimate and report.

The scope of the project was definedusing intelligent P&IDs, and layouts weredeveloped to facilitate material take-offsfor earthworks, civil, structural, piping andelectrical and controls.

This study represented a challenge with tightschedule and work over the Christmas/NewYear period.

Project commencement to submission

of the report took 13 weeks in line withclient requirements, and was completedunder budget.

THE RIGHT SIZE FOR BETTER ENGINEERED SOLUTIONS

www.intechengineers.com.au

INTECH UPDATES

April - June 2013

MILESTONE ACHIEVED:LADY ANNIE PUMPSCOMMISSIONED

CHILEAN SX/EWSTUDY COMPLETED

WHAT’S

INSIDE

PAGE 2

PAGE 3

PAGE 4

DISCUSSION

AVOIDING HARMONIC

DISTORTION

REDUCING COSTS USING

SELF-PRIMING PUMPS

DISCUSSION

COST SAVINGS WITH CIVIL

CONSTRUCTION

A NOTE FROM JEFF

SPOTLIGHT DAVID NOLAN

CONTACT DETAILS

Lady Annie Pumps Commissioned Chilean SX/EW Feasibility Study



High levels of harmonic distortion canpotentially be harmful to a power system andequipment and may be non-compliant to

supply authority contracts. The most commonsource of harmonics in an industrial plantare those created by Variable Speed Drives(VSDs).

CONSEQUENCES

Some effects of harmonic distortion are:

overheating of electrical equipmentincluding conductors, transformers, motorsand generators;

interference with electronic equipment;

spurious tripping of protection equipmentcausing disruptions to power supply.

REDUCING DISTORTION

Harmonic distortion can be reduced toacceptable levels by the use of harmonic

filtering. The optimal location for harmonicmitigation is at the source of the distortion,which would either be at the VSD itself or atthe switchboard which the VSD is connectedto. Doing this will prevent distortion beingspread throughout the power system networkaffecting other connected equipment.

In some cases it may be appropriate to havea single large harmonic filter at the site’s mainhigh voltage substation rather than smallerfilters connected locally at the VSDs.

If an investigation reveals that harmonicdistortion levels are acceptable for theequipment in the plant but are unacceptableat the point of common coupling to the publicpower grid then a single unit may be thesolution.

GUIDELINES

The harmonic limits specified in theinternationally recognised standardsIEEE519 and Australian Standard AS/NZS61000.3.6 can be used as a guidelinefor a harmonic distortion investigation.

In some instances there may be morestringent harmonic limits that may need

VARIABLE SPEED DRIVE

to be met, however this will depend onthe particular equipment and specific siteinstallation requirements.

SOLUTION

Some recognised methods of harmonicdistortion mitigation for VSD equipmentinclude: 12-Pulse or 18-Pulse VSDs rather than

6-Pulse

Passive harmonic filter

Active harmonic filters

An investigation into harmonic distortion

is recommended when VSD’s and anyother significant non-linear loads are beinginstalled. The effort at the initial stages of aproject is well justified when considerationis given to the potential for plant downtimeand significant costs and that may beincurred to retrofit harmonic filteringequipment at a later stage.

Mark Poli - Principal Electrical Engineer

DISCUSSION

AVOIDING HARMONIC DISTORTION

2

INTECH UPDATES

Heap Leach Stacking and Leach Pads



Priming is the process in which air in thesuction side of the pump and piping is

removed so that the impeller of a centrifugalpump is fully submerged and the pump is notprevented from pumping. Priming is neededwhen pumps are shut down and “loseprime” and when this happens it can beboth problematic and time consuming. This isa bigger problem in remote locations suchas pumping from ponds, dams,and the like.

SOLUTION

A solution to priming problems is to have

either a self-priming unit adjacent to thepump or an internal priming pump to createthe required vacuum and to relieve thesuction inlet from any air before start-up.Intech has implemented both systems withsuccess and found that the incremental costsof these systems are often more than offset bythe operation savings in reduced labour andlost down time.

The costs of earthworks have risensignificantly—particularly in Australiaover recent times.

Project overheads add to costs, such asmobilisation, supervision and lost productivity.Other contributing factors include a lack ofcompetition, increasing margins and lack ofskills including estimating which increase riskcomponents in tenders.

Typical drivers for direct civilconstruction costs are:

Plant ownership leasing 30%;

maintenance, fuel & tyres 30%;

labour 40%.

The cost of labour in Africa may be lower,however we have seen lower labourproductivities offset the potential gains.

Some guidelines for effectiveearthworks are:

Careful siting of facilities: laying out plantsites and working with the contours tominimise cut, avoid natural obstacles,and cut down to rock or sound materialfor foundations.

Understand the costs: Less than optimaldecisions are commonly made becausethe costs are not understood. Earlyestimates that are refined are invaluable.

Use local materials: Use local gravels,rock, clay where practicable. Mine wastecan be free and if it’s available can beincorporated into fill, allowing significantsavings can be made. We have usedmore waste for ROM pads, building padsand dams.

Balanced cut to fill: Any excess materialthat is stockpiled or material that has to be

borrowed adds to costs. Use of modern

3D civil modelling software and running

multiple iterations may initially increase your engineering cost, however usuallyhas significant savings in the end.

Move it once: Every time earth is pickedup and moved it typically costs at least$5/bcm. Careful planning can ensurethat it is put where it can be used thefirst time.

Bigger is Better: Larger plant is cheaper.Think of 100t trucks at $5/bcm and 50ttrucks at $10/bcm.

A good contract solution: A proper tenderprocess based on a clear, well thoughtout scope can save you money. We havefound that a competitive tender processpotentially saves around 15% of thecontract cost.

Good contract administration: Effectivecontract administration features closesupervision and accurate measurementof quantities and payment.

Jeff Sterling—Managing Director

DISCUSSION

COST SAVINGS WITH CIVIL CONSTRUCTION

DETAIL ON A SELF PRIMINGCENTRIFUGAL PUMP

REDUCING COSTSUSING SELFPRIMING PUMPS

3

MRM Tailings Storage & Water Management Dams




Some words of wisdom were published inthe AFR recently from “leading thinkers”. Weworked with one of them, Chris Baker fromCaledonia, on one of our first gold mine jobsin the Pacific.

We, like everyone else look to our sages of theindustry to give us some indications of futuredirection. I took away these points:

The rough time for the resource companies

in the last 6 months has featured poorcapital investment, changes in seniormanagement in Rio and BHP;

Gold Investment: Large economies areprinting money which should drive up theprice of gold but large funds are unwindingpositions which have the opposite signal.The conclusion is that it’s hard to predictfuture gold price;

There is a focus on GDP target of 7.5%however the Chinese economy has tripled insize over the last 10 years and so demandshould not decrease. China steel production

is forecast for 700 to 750 Mtpa this year.US steel production peaked at 200 Mtpaand is now at 100 Mtpa, whereas theprediction for China is 1,000 Mtpa.

BRISBANE OFFICE

95 BRUNSWICK STFORTITUDE VALLEYQUEENSLAND 4006

TOWNSVILLE OFFICE

5/175 STURT STTOWNSVILLEQLD AUSTRALIA 4810

PERTH OFFICE

853 WELLINGTON STWEST PERTHWA AUSTRALIA 6005

We extend a warm welcome to Davidwho joins our team at Intech after anumber of years with Sedgman.

He has an MBA and B.Eng (Mech) andsubstantial experience in EngineeringManagement and as a Study Leader.He has worked on studies for clients inQueensland, NSW and Mozambique(largest study value approx. $3.6M,largest capital estimate approx. $1.9B).

David has 17 years’ experience in themining, construction and rail industries,and in addition to the above hasworked as a Project Engineer andProject Manager.

He spends his spare time chasing afterhis three kids (with a 4th on the way)

and frantically trying to finish homerenovations before the baby arrives!We wish him well and welcome him tothe team.

TELEPHONE

(INTERNATIONAL) +61 7 3666 0006(AUSTRALIA) 07 3666 000

Currently we are providing solutions from SouthAmerica to West Africa, ranging from bulkcommodities to precious metals. We find inmany areas, industry standards are higher thanever before and there is often not a tolerance tolet younger people learn on the job.

A greater emphasis is required for up-skillingour up-and- coming engineers and managers

and to be better we are working on ourmanagement and systems to meet moredemanding requirements.

Outcomes are our focus and to improve tomeet our aspiration of providing best possibleproject results.

Ian Alcock, an experienced manager andmentor has been guiding the programmeand we have found beneficial a trainingexercise called “GPS”, where we have beenparticipating to raise the profile of our corevalues of integrity, commitment and highperformance outcomes.

Almost tying in with the completion of theconstruction of stage 3 of the lady Annieproject was the commencement of the feasibilityfor another copper oxide project. Our taskcommenced prior to the Christmas break anda big effort was put in by a few to finalise adesign and pull together a capital estimate forthe project. Our graduate mechanical designengineer Helen Walker deserves a specialmention for her commitment over what was theholiday period for others.

A NOTE FROM JEFF SPOTLIGHT

MRM Water Management

DAVID NOLANSTUDY & BUSINESS

DEVELOPMENT MANAGERB.Eng (Hons). RPEQ. MBA


www.intechengineers.com.au

int newsletter april-june web

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