Nullagine Gold Project

Millennium commences gold production from expanded sulphide plant at Nullagine

Millennium Minerals (ASX: MOY) has announced a milestone update after the successful commissioning of its A$15 million stage one sulphide plant expansion at Nullagine Gold Project in WA.

The company reported that the stage 1 sulphide plant expansion has delivered first gold production from sulphide ore.

Millennium Chief Executive Peter Cash said that all early results from the sulphide circuit had been very positive, indicating the potential to generate strong, profitable gold production from sulphide ore.

Nullagine gold project

Millennium’s 100%-owned Nullagine Gold Project is located in the East Pilbara region of Western Australia, approximately 185km north of Newman.

The production from Nullagine has traditionally been sourced from open pits, however mining commenced at the Company’s first-ever underground mine at Bartons in late 2018 and a second underground mine is scheduled to be developed at Golden Gate in Q3 2019.

The ore is processed at the 2Mtpa Golden Eagle CIL ore treatment plant, with the ore delivered from multiple ore sources to a 150,000 tonne capacity stockpile.

Sulphide expansion project

The company is currently working on the expansion of the Golden Eagle plant to accommodate the treatment of sulphide ore.

The sulphide expansion project is broken into three distinct phases. The first phase is the Stage 1a, which includes concentrator and fine grinding circuit (now in operation).

The second phase is the stage 1b which comprises of the installation of the in-mill oxidation (INOX) process as the concentrate transitions from a pyrite-dominant to a blended pyrite / arsenopyrite ore;

The third phase is the stage 2 which comprises of pressurised in-mill oxidation (PINOX) to facilitate the processing of arsenopyrite-dominant ore.

The company said that the completion of the Stage 1b and Stage 2 upgrades will be timed to maximise cash flow based on the mine schedule.

Millennium noted that the ability to cost-effectively process sulphide ore represents a key element of the Company’s longer-term growth and development strategy, opening up a large portion of the Nullagine Reserve base as well as delivering a range of new, high-grade exploration targets.

Gold delivered from stage 1 sulphide plant expansion

The company had recently completed the successful commissioning of the stage 1 sulphide plant expansion at Nullagine. Gold has now being recovered from sulphide concentrate.

Millennium said that the delivery of first gold from sulphide ore represents a major milestone for the Company, marking the culmination of detailed development studies and optimisation programs completed over the past four years.

Expanded sulphide circuits performing as expected

Millennium reported that the early analysis indicates all components of the expanded sulphide circuit are performing in line with or exceeding feasibility expectations.

MOY said that the commissioning of Ultra-fine Grind Mills was undertaken over 19-24 June, with higher sulphide feed stockpiles now starting to be processed along with freshly generated product from the concentrator circuit.

The company noted that concentrate grades over the past six weeks is averaging ~3g/t Au. This is an upgrade of +13-times the average concentrator feed grade.

With the expected concentrate generation rate going forward and the installed mill capacity, it is expected that the stockpiled concentrates will be processed over a 4-6 week period.

Millennium reported that Bartons Underground is performing well following implementation of a new mining sequence, with ore production rates of over 1,000 tonnes per day being achieved on a regular basis and the grade profile within expectations.

Future plans

The company said that over the remainder of 2019, approximately half of Millennium’s ore feed will come from sulphide sources.

MOY said that the optimisation of the sulphide circuit is continuing, with test work underway on fresh concentrates generated in the plant.

Millennium announced that the completion of Stage 1 plant upgrade is expected to underpin strong uplift in gold production and head grade in 2H CY2019, with the mine schedule shifting towards high-grade sulphide deposits that can now be economically processed through the expanded circuit.

The company said that a further update on gold recoveries and production metrics will be provided in its June 2019 Quarterly Activities Report that is scheduled for release in late July.

Management comments

Millennium Chief Executive Peter Cash said: “The ability to cost-effectively process the high-grade sulphide ore sources at Nullagine has been a core component of Millennium’s growth plan over the past four years, and we are absolutely delighted to have successfully achieved this milestone.

The past 14 months have been a very capital-intensive period for the Company, where we have made significant investment in long-term growth initiatives including the sulphide plant expansion and the development of sulphide ore sources.

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Written By Christopher Norris
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