A higher ratio of Golden Gate ore milled and improved mining performance has resulted in the production of 19,699 ounces of gold in the December quarter 2014. This is higher than its guidance of 18,000 ounces.
Millennium Minerals (ASX:MOY) is focused on gold production from the company's Nullagine Gold Project in Western Australia.
A higher ratio of Golden Gate ore milled and improved mining performance has resulted in the production of 19,699 ounces of gold in the December quarter 2014. This is higher than its guidance of 18,000 ounces.
The Nullagine Gold Project continues to perform strongly for Millennium Minerals with September quarter output of 18,127 ounces exceeding guidance. Both C1 cash costs and sustaining cash costs were reduced by 8%.
The Nullagine Gold Project continues to perform strongly, achieving its production target of 36,551 ounces of gold for the 6 months to 30 June 2014. Revenues for the half-year were A$55.3 million with cash operating margins of $386 per ounce.
With gold production from Millennium Mineral's Nullagine Gold Project in Western Australia coming in at the upper end of its guidance and a restated Resource expected this quarter, managing director Brian Rear will have much to discuss with investors in Melbourne. Register today.
A rising gold price could deliver a re-rating to gold-producer Millennium Minerals, with the company's shares expected to open high today as gold trades at A$1400 an ounce.
27/07/15Millennium Minerals shines in turnaround, posts record gold sales
31/12/14Millennium Minerals director steps down
23/12/14Millennium Minerals signs term sheet for increased funding
18/12/14Millennium Minerals appoints Glenn Dovaston as chief executive officer
16/12/14Millennium Minerals to mine central deposits at Nullagine Gold Project
No documents available.
Millennium Minerals Limited (ASX Code: "MOY") is an emerging gold company focused on the exploration and development of a large tenement portfolio in the East Pilbara region of Western Australia.
In late 2009 the company updated the feasibility study prepared in 2007 that assessed the viability of developing a gold production operation centred on multiple ore bodies contained within its East Pilbara tenement holdings. Although the 2007 study demonstrated a viable project at the time the Board of Directors deferred the development given the tough external business environment that existed, having regard to gold prices, skills shortages and the extended delivery periods for supply of capital equipment.
The 2009 update brought to account additional resources and reserves, a higher gold price and an absence of the constraints to sourcing skilled people and capital equipment experienced in 2007.
Millennium Minerals has now completed it's debt financing and through three captial raisings through 2011 and 2012 has raised sufficient equity to fund the development of the gold mine forecast to produce 504,000oz gold over a seven year period. In parallel with the development of the project the company is continuing exploration with a plan to continue mineral resource and ore reserve development, tapping into the significant geological potential that the company has established.
Millennium Minerals business plan is to move to revenue generation with the development of the gold project, repay any debt promptly and re-invest surplus funds in future dividends with organic and inorganic growth to achieve mid tier status within the Australian resource industry over the next five years.
Results from the 2010 feasibility study indicate the following operational and financial metrics.
- Stage 1 Mining Ore Reserve of 10.45 Mt at 1.7g/t containing 567,000 ounces, using a cut-off grade of 0.5g/t.
- Initial mine life of 7 years, producing 504,000 ounces from CIL process plant.
- Process Plant and Infrastructure development capital cost $87 million including $6 million in contingency.
- Native Title completed, final permitting largely complete.
- Inferred resource areas and depth extensions provide upside.
- Stage 2 scoping study to evaluate a higher throughput rate based on the 2011 updated ore reserve estimate totalling 16.3 million tons at 1.4 grams per ton for 741,000 ounces of gold.
Mine design and scheduling is driven by a desire to maximise gold production in the first four years of the project life. The base case plan shows milling throughput rates of 1.50Mt per annum generating 72,000 ounces of gold.
The production plan recognises the 2010 ore estimate of 504,000 recoverd ounces exploration activities comleted in 2011 led to an updated ore reserve in late 2011. To bring this to account, the company is undertaking a scoping study to determine what throughput rate would maximise gold recoveries closer to 100,00 ounces.
In addition, depth and strike extension potential exists that will require further gold exploration to define. These upside factors require assessment, and if their potential is realised, brought into the project well before Year 4 with the potential of producing an increase in gold output.
MINE OPERATIONS AND PROCESS FLOW SHEET DESCRIPTION
The General layout of the planned process plant is shown in Figure 1.
TREATMENT PLANT SITE
The treatment plant site is located approximately 10 kilometres south of the Nullagine town in Western Australia. The plant site is located immediately south east of a 60 metre high natural ridge - the topography being relatively flat with minimal vegetation. Occasional rock outcrops are present across parts of the area, however, surface conditions primarily comprise clayey sands and gravels.
Ground conditions have been assessed as suitable to support loads typically associated with plant infrastructure. The proposed size cuts and fills of the site will be carried out to provide the required leveling for construction. The ROM pad base course will be constructed from waste and will grow to the full designed size, using low grade ore as it becomes available from mining operations.
As the area is one of the hottest in Australia, work areas and equipment conditions will be designed to take into account addressing these adverse climatic issues.
ROM PAD OPERATION
The mining workforce will mine and deliver ore from the Project's various open pits, which will be hauled to the 150,000 tonne capacity ROM stockpile area located adjacent to the crusher. A Caterpillar 980 size Front End Loader (FEL) will rehandle the ore into the ROM crusher feed bin for crushing.
Ore stockpiles will generally be situated within a one hundred metre radius of the crusher ROM bin. Separated "fingers" or smaller stockpiles of ore will be developed to account for varying material hardness and ore grade, allowing for blending and throughput optimisation.
The primary crusher will be fed from a 1500 tonne live capacity ROM bin with a 800 mm nominal feed size. Any oversize rock will be broken in situ by a rock breaker mounted adjacent to the ROM bin, with feed rate controlled by a variable speed apron feeder.
The jaw crusher will operate with a closed side setting of 125 mm, which will result in 80% of the feed passing 100 mm. A five tonne monorail hoist will be mounted above the primary crusher to allow for the replacement of the jaw liners during maintenance.
Crushed material will be transported using conveyor belts to a 50,000 T live capacity coarse ore stockpile. Two variable spread apron feed will draw from the stockpile feeding the SAG mill. One of the apron feeders acts as an emergency feeder and feeds the mill via use of a front end loader during periods of crusher maintenance, ensuring a constant ore supply.
The grinding circuit will comprise a single stage 4,000 kW SAG (Semi Autogenous Grinding) mill in closed circuit with hydrocyclones. The SAG mill (5.7 m long and 6.1 m in diameter) will be operated with a ball charge of 16% - consisting of 100 mm diameter steel balls. A grate discharge arrangement will prevent oversize material from passing through the mill without grinding.
Mill discharge slurry will pass through a 15.5 mm by 15.5 mm aperture trommel, into the mill discharge hopper. Pneumatically controlled knife gate valves will be used to control and isolate pump feed allowing for pump maintenance while in operation.
Slurry from the SAG mill will be pumped up to a cluster of eight hydrocyclones where it will be split into two streams, the overflow and the underflow. The cyclone overflow will have a P80 of 106 microns and will gravity feed onto two vibrating trash screens with 0.6 mm aperture to remove any oversized material. Oversize material from the trash screens will be returned to the mill, via a flop gate chute arrangement. Undersized material continues into the leach circuit.
The cyclone underflow will be returned to the mill. A proportion of the underflow flows over a vibrating screen and undersized materials report to a KCXD30 Knelson centrifugal gravity concentrator to remove any 'free' gold. The screen oversize will be directed back to the mill feed chute, while the Knelson concentrator tails will be returned to the mill discharge launder.
Knelson concentrate material will be drawn off and pass to a storage cone situated in the goldroom. The storage cone will be mounted over an CS500 Acacia intensive leach reactor and batch treated daily.
The cyclone overflow from the trash screens passes into the CIL circuit. This circuit will consist of nine m high by ten m diameter tanks each holding approximately 833 m3 of slurry with mechanical agitation to prevent sanding.
A plant control room will be located at the same level as the top of the tanks, providing views to the feed conveyor, mill, discharge and tailings pumps as well as being in close proximity to the trash screens, cyclones and gravity circuit.
Sodium Cyanide solution will be added to the circuit through a rotameter installed in the cyanide distribution pipe ring main.
The slurry flow from each tank to the next, pass through a 1.0 mm wedge wire intertank screen flowing via a launder to the following tank.
Tank three will be the first of the seven absorption tanks that will contain activated carbon. These seven tanks are arranged in series and will operate in a counter current manner with the slurry passing from tank three to tank nine and the carbon pumped forward from tank nine to tank three using recessed impeller pumps. A five tonne portal crane will be mounted above the tanks to facilitate removal of the intertank screens, agitators and trash screens for maintenance.
Once the carbon reaches tank three, it will be pumped over a vibrating recovery screen with an aperture of 1.0 mm. The clean carbon will fall into an elution column and the slurry will be returned to tank two.
The first three tanks will be fitted with oxygen injection to accelerate absorption of gold. Provision for a three tonne per day PSA oxygen plant has been made in the design, located adjacent to tank four.
The slurry, once it has passed through the intertank screen in tank nine, will gravity feed to a vibrating tails screen with 1.2 mm aperture panels. The screen will recover any carbon that may have passed through the final intertank screen.
Diluted water and flocculant will be added to the slurry before it enters a 20 metre diameter high rate thickener, where it will be thickened to > 55% solids. The overflow water will be recycled and pumped directly to the process water dam for reuse in the plant. Thickener underflow reports to the tails hopper and is pumped to the TSF.
Process plant tanks will be constructed on concrete ring beams within a concrete bunded containment structure with three sumps and pumps returning water, overflow and spillage back into the circuit.
ELLUTION / GOLDROOM
The loaded carbon in the elution column will be stripped of gold by the AARL method of elution. This involves the following:
- Acid washing of the carbon with dilute hydrochloric acid.
- Stripping of the carbon using a solution of cyanide and caustic heated to 120 C at 350 kPa.
- Electrowinning of the gold laden solution onto steel wool cathodes.
The elution column will have a volume of 8 m3 and be capable of holding in excess of three tonnes of carbon. It will be constructed of stainless steel suitable for acid washing and elution.
The dilute acid wash solution will be prepared prior to stripping by mixing concentrated hydrochloric acid and raw water into a dilute acid tank. During acid washing the dilute solution will be pumped into the bottom of the column to remove contaminants from the carbon. After soaking, the carbon will be rinsed with water to displace any residual acid - with the acid and rinse water being disposed of back into the circuit;
Sodium hydroxide and cyanide solutions will be combined with potable water to achieve a strip solution. The strip solution will be circulated through a heat exchanger, prior to entering the base of the column. After soaking, heated water will be pumped through the column to remove the remaining gold from the loaded carbon. The pregnant eluate and rinse water will be directed to an eluate tank for gold recovery by electrowinning.
Once the elution process is complete, the pregnant solution will be pumped into a closed circuit for electrowinning cells contained in the goldroom. DC electric current will be passed through stainless steel anodes and steel wool cathodes causing the gold in solution to plate out on the cathodes until the solution is barren. This will take approximately 16 hours after which the barren solution will be pumped back into the circuit.
Barren carbon will be returned either directly to the circuit or to the regeneration kiln. The horizontal kiln will operate at 650C, at a rate of 200 kg per hour regenerating the carbon to > 90% of its original activity over approximately 15 hours. Discharge from the kiln will be cooled and released directly back into the circuit.
The gold sludge will be removed from the electrowinning cells then dried in an oven prior to smelting in a gas fired furnace to produce the gold bullion (dore`) bars.
The TSF will be located approximately 1 kilometre north west of the plant site and will be approximately 42.6 hectares with a designed maximum embankment height of 17 m. Initial construction will provide for the first eighteen months production by building a starter embankment up to 7 m in height.
Tailings will be pumped via a single 250 mm pipeline from the plant to a junction point at the crest of the dam. This junction point will allow diversion of the tailings and flushing of the lines. A pipeline with multipoint spigots will be located on the three constructed TSF walls, where the tailings will be deposited along the walls.
Surface water recovered from the tailings slurry will be collected into a rock walled decant pond where it will be pumped back through a single 160 mm OD pipeline to the plant process water dam for reuse.
Quicklime used to stabise pH levels in the process plant will be delivered in bulk by double road train tankers in 58 tonne loads. The quicklime will be pneumatically discharged into a 100 ton silo.
Cyanide deliveries will be in bulk by iso-tankers holding 22.5 tonnes of solid cyanide briquettes containing 98% sodium cyanide. As part of a facility leasing agreement, the supplier will provide two iso-tankers, a sparging facility and two x 165kl storage tanks. The solid cyanide will be sparged by an automated system as required into the storage tank. Solution in the tank will be pumped to the leach tanks where it will be manually regulated to maintain the desired cyanide levels.
Grinding media will be delivered in 80 tonne loads by road transport. A charge of 100mm steel balls will be added via the emergency apron feeder to maintain optimimum bll loading in the mill.
Carbon will be delivered by road transport in 600 kg bulka bags. A store of bags will be held on site with carbon added directly into the leaching circuit on a regular basis to maintain carbon levels.
Oxygen will be generated by a three tonne per day PSA plant provided and maintained by the supplier. Approximately 60 m3 of oxygen will be produced an hour, which will be sparged as required into the first three leach tanks to maintain enhanced dissolved oxygen levels.
Deliveries of caustic soda will be by road train tanker in 30 cubic metre loads of 50% concentration bulk liquid. The liquid will be discharged into a 55,000 litre storage tank ready to be pumped for direct use in the elution circuit.
Hydrochloric acid will also be delivered by road train tanker in 2 cubic metre loads of 32% concentration bulk liquid. The liquid will be discharged into a 46,000 litre storage tank ready to be pumped to the dilute acid tank for use in the elution circuit.
LPG deliveries will be by road train tanker in bulk liquid and discharged into six 7,500 litre storage tanks provided by the supplier under a facility agreement for use in the carbon regeneration kiln and gold room smelting furnace.
Diesel will be delivered by road train tanker into six 114,000 litre storage tanks. An automated pumping system will maintain fuel supply to a day storage tank at the powerhouse. A bowser will also be provided for use in refuelling vehicles.
Power for the mine site will be supplied by a contractor owned and maintained multiple diesel generator power house. Nine diesel generators rated for 1mW on a continuous basis will be installed with seven operating at any one time. Under the supply agreement the contractor will supply the facility for the generators as well as the main switchboard and control panels housed in the switch room.
Overhead power lines will run from the power house to the earthmoving contractor's yard, borefield, camp and the tailings storage facility for pumping return water.
Water for the milling circuit will be pumped from the production bores as well as return water from the tailings dam. Lined water dams will be constructed adjacent to the plant to store process and raw water. The raw water dam will be designed to overflow into the process water dam.
The plant water demand based on a thickened slurry density of 55% to 60%. Based on a mill availability of 95%, total water needs will range from 700,000 m3 to 850,000 m3 per annum. With minimal return water to the process water dam from the tailings storage facility the average make up water consumption of 0.7 tonne of water per tonne of ore milled is estimated.
Potable water will be produced by an RO plant fed by the raw water.
PROCESS CONTROL SYSTEMS
System control has been deliberately designed for simplicity and where practicable manually operated with minimal automation. A main control room will be provided in the plant on top of the CIL tanks, with a smaller control cabin in the crushing area. Instrumentation will be provided within the plant to measure normal process control.
Discrete regulatory controllers will be located either in the control room, or in field mounted control panels. Details of these control loops are described below. Status information on selected process drives and process states will be collected by a Programmable Logic Controller (PLC) and displayed on control room computer monitors. Process and Instrument Diagrams (P & ID) to display the process and the status of all drives and main process conditions, as well as fault alarms, will also be displayed on control room computer monitors.
All major drives will have a field mounted control station to allow local start and stop, as well as remotely controlled from the appropriate control room. The control circuits for each starter will be hard wired with relay logic for any interlocking requirements. Sump pumps and intertank screens will be provided local electrical isolators to facilitate maintenance periods.
PETER ROWE (CHAIRMAN)
Mr Rowe has broad international mining industry experience gained over a 35 year career based mainly in Australia and South Africa. Following 20 years with Anglo American and De Beers, he moved to Australia in the early 1990s. Mr Rowe was project director of the Fimiston Expansion (Kalgoorlie Superpit), general manager of the Boddington Gold Mine and of the Boddington Expansion Project and managing director and CEO of Bulong Nickel. He headed up AngloGold Ashanti Australia and then moved to Johannesburg where he recently retired from his position there as executive vice president - business effectiveness. He is currently a non-executive director with three ASX listed companies.
Mr Rowe holds a chemical engineering degree and is a Fellow of the AusIMM and of the Australian Institute of Company Directors.
RICHARD PROCTER (NON EXECUTIVE DIRECTOR)
Mr Procter is a mining engineer with over 30 years broad international experience encompassing roles in the corporate, operations, contracting and mine development areas. Mr Procter has held senior industry positions that have demonstrated leadership and management of base and precious metal mining companies (including both underground and open pit operations); the assessment and development of projects including definitive/bankable feasibility studies and converting studies into mining operations; managed teams undertaking mining asset evaluations and valuations (for mergers and/or acquisitions). He also has been involved in many mining operation start ups (both small and large scale) - as well as the re-engineering of organisations. Mr Procter continues to provide technical and strategic planning advice to both mining and industrial companies.
ROSS GILLON (NON EXECUTIVE DIRECTOR)
Mr Gillon is a solicitor in Perth and has previously been a director of a number of exploration companies.
JOHN MORTON (NON EXECUTIVE DIRECTOR)
Mr Morton is Chief Portfolio Manager of Heritas Capital Management (Australia), where he has worked for the past six years. He has more than 17 years’ experience in investments, strategy and corporate finance both in Australia and abroad having previously worked with Rio Tinto and Ernst & Young Corporate Finance.
He has a Master of Applied Finance, Bachelor of Arts and Bachelor of Commerce and is a member of the Institute of Chartered Accountants (ICAA).
BRIAN REAR (CHIEF EXECUTIVE OFFICER)
Mr Rear is a graduate of the Western Australian School of Mines (AWASM Metallurgy), The Royal School of Mines (MSc London, Mineral Process Design, DIC) and holds a Masters Degree in Business Leadership from the Business School of the University of South Africa. He is a member of the Australian Institute of Company Directors. He has extensive experience in process engineering, project development and company management having successfully developed three green-field projects and the turnaround of a fourth covering base metals and thermal coal. His career includes stints with Rio Tinto, Anglo Vaal Limited, Straits Resources and CopperCo Limited.
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