Australia

Hellyer Mine

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Overview

Mine TypeTailings
Commodities
  • Lead
  • Zinc
  • Silver
  • Gold
  • Copper
  • Pyrite
Mining Method
  • Dredging
Production Start... Lock
Mine Life7.8 years (as of Jan 1, 2022)
ShapshotHellyer Gold Mines started retreatment of tailings from the historic main tailings storage facility in October 2018.

On February 2022, EnviroGold Global has executed a binding definitive agreement with Hellyer Gold Mines Pty Ltd to reprocess the tailings at its Hellyer Gold Mine in Tasmania, Australia.

The EnviroGold operations at Hellyer will be undertaken in two stages. The first stage operation is designed to treat 500 tonnes per day (tpd), with the second stage expansion designed to treat 3,500 tpd.

Implementation of Stage 1 Commercial processing in 2023.

No financial and production data documents were published during the period of formal Administration.

Owners

SourceSource
CompanyInterestOwnership
NQ Minerals Plc. 100 % Indirect
The Hellyer Project is in north-western Tasmania. The current mining tenure is Combined Mining Lease CML103M/1987 covering an area of 1,695 hectares held by Hellyer Gold Mines Pty Ltd. (HGM).

The HGM parent company, NQ Minerals Plc, was placed into Administration on 9 August 2021 by a unanimous vote of the Directors of the Company. Munich Partners of Sydney Australia successfully purchased Keen Pacific (the HGM holding company) out of Administration.

Contractors

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Deposit type

  • Tailings

Summary:

Deposit Types The original Hellyer massive sulfide deposit has been interpreted by most previous workers as a classic, seafloor, mound-style, VHMS deposit, developed in a similar manner to the classic Kuroko deposit (Gemmell and Large, 1992; Large, 1992; McArthur, 1996). Gemmell and Large (1992) described the hydrothermal alteration zonation pattern centred around the stringer zone and interpreted the metal zonation of the deposit to delineate the main feeder zones. McArthur (1996) examined the metal content, mineralogy, macroscopic and microscopic textures, and mineral trace element composition of the massive sulfide deposit in detail and supported the formation of the sulfide mound by deposition of sulfides at or near the seafloor with in-situ recrystallisation, intra-mound veining, upward deposition, and thermal retraction. This mound building and zone refining process, described by Eldridge et al. (1983), is responsible for the Cu-rich base of the deposit with an upward and outward increase in Zn and Pb content. Mineralisation is comprised predominantly of pyrite and sphalerite, with lesser galena and arsenopyrite. The deposit under review is a tailings dam, comprised of sediments pumped into a natural depression within a compacted earth-fill dam. The tailings sediments were sourced from the adjacent Hellyer Mine processing facility which processed polymetallic ore sourced mainly from the Hellyer underground mine plus some from the Fossey mine and the Que River mine. The tailings are predominantly crushed and ground waste products from the processed ore, with the bulk of the volume being sands, with lesser amounts of sulfides and some free metals. The processed Hellyer tailings now comprise a localised sedimentary sequence deposited within an artificial basin confined by the retaining wall of the Hellyer TSF. Previous evaluation of this recent anthropogenic deposit has been by a series of drill programmes using vertical drill holes to recover cores of the sediment.However, the deposit under review is the tailings in the Hellyer tailings storage facility, comprised of sediments pumped into a natural depression with a compacted earth-fill embankment constructed to contain the material. The tailings sediments were produced by the adjacent Hellyer Mine processing facility that processed polymetallic ore sourced from the Hellyer underground mine. Hellyer Mineralisation Wu (2014) described the Hellyer deposit as being “dominated by massive sulfide ores with an average of 54% pyrite, 20% sphalerite, 8% galena, 2% arsenopyrite, and 1% chalcopyrite with minor tetrahedrite (McArthur and Dronseika, 1990). Gangue minerals including quartz, barite, calcite, chlorite, sericite, and siderite make up the remaining ~15% of the orebody. Sulfide accumulation is restricted to a single lens that has been bisected by faulting, but with essentially no internal waste. The massive sulfide ores were subdivided into four types by McArthur and Dronseika (1990): 1. Footwall Depleted Zone – inner footwall portion with; 2. Hanging-wall Enriched Zone – hanging wall portion and outer regions with >100 ppm Ag, elevated Pb, Zn, Ag, Au, As; 3. Baritic Cap – massive barite with minor massive sulfide “slugs’, stratigraphically above the hanging wall enriched zone; 4. Siliceous Cap – pyritic “chert’, stratigraphically above the hanging wall enriched zone. Textural variations in sulfide mineralogy at Hellyer are complex and macro- and microscopic features were documented comprehensively by McArthur (1996). Macroscopically, the massive sulfide texture is classified into six endmembers: massive, banded, boxwork veining, fragmental, recrystallised, and shrinkage shadows (McArthur, 1996). Massive textures are dominant throughout, but the richer ores in the hanging wall enriched zone tend to be banded and vary from alternating planar layers of pyrite and sphalerite ± galena ± arsenopyrite, to contorted discontinuous layers, to fine, wispy sphalerite ± galena in a pyrite matrix (McArthur and Dronseika, 1990). Recrystallised textures are concentrated proximally over the interpreted core of the footwall alteration zone (Gemmell and Large, 1992) while banded and shrinkage shadow textures are more common in distal positions. Fragmental ores concentrate at the footwall in topographic lows on the seafloor as reconstructed by Downs (1993). Microscopically, the sulfide textures are diverse and very fine-grained with many delicate depositional textures preserved (McArthur, 1996). Pyrite occurrence ranges from spongy, melnikovite, to anhedral with interstitial galena, to well-developed cubes. Colloform and ultrafine intergrowths of pyrite with other sulfides are commonly observed, especially with galena and arsenopyrite (McArthur, 1996). Sphalerite also occurs as fine-grained masses with intergrowths of pyrite, galena, and arsenopyrite. Chalcopyrite disease in sphalerite is most strongly developed towards the footwall (McArthur and Dronseika, 1990). Sphalerite intergrowths with chlorite are also common, but not with any other gangue minerals (McArthur, 1996). Galena is generally more coarse-grained and occurs as partly re-crystallised clusters, thin veins and minute blebs throughout the sulfide matrix; intergrowths of galena with sericite are also common. Near the hanging wall, tetrahedrite is present as intergrowths with galena, as veinlets cutting galena, sphalerite and pyrite, as shells around colloform pyrite, or as minute grains within sphalerite (McArthur and Dronseika, 1990). Literature review and mineragraphic analysis of samples from Hellyer suggest that historical low levels of precious metals recovery from Hellyer ore is due to the gold and silver predominantly occurring in “solid solution’, a solid mixture containing a minor component uniformly distributed within the crystalline lattice structure of (at Hellyer) pyrite and arsenopyrite (Teale, 2021). Such occurrences are not amenable to recovery via the industry standard milling and processing methods utilised at Hellyer Stratigraphically above the massive sulfides is the baritic cap, which is largely composed of massive barite layers up to 15 m thick with irregular bands and clots of sphalerite, galena and tetrahedrite (McArthur and Dronseika, 1990). The barite cap is bounded by the orebody extremities and forms a semi-continuous elongate lens above the massive sulfide mineralisation. The contacts between the barite cap and massive sulfides vary from sharp and irregular to diffuse (Sharpe, 1991). Barite occurs as massive interlocking grains to well-formed crystalline tabular laths up to 10 cm in size (Sharpe, 1991). Intergrowths of barite are common and radiating barite aggregates are also observed. Barite grains in zones with high sulfide content tend to be rounded and fractured, suggesting some degree of redeposition and dissolution (Sharpe, 1991). Overlying the barite, and to a lesser extent, there is a thin layer of highly siliceous precious metal-rich ore with approximately 40% sulfides and well preserved primary colloform and framboidal textures (McArthur and Dronseika, 1990; Sharpe, 1991). This siliceous cap is also known as the glassy silica pyrite (GSP) unit for its distinctive pyritic textures in a grey, glassy siliceous matrix. The occurrence of the GSP is discontinuous, but generally correlates with that of the barite cap, with the exception of a few lenses where the GSP lies directly on top of the massive mineralisation (Sharpe, 1991). Interdigitating contacts, siliceous vein transect the barite cap and fragmental barite in the GSP suggest the formation of the barite and GSP were near contemporaneous (Sharpe, 1991).

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

Following modifications to the process plant and a cost benefit analysis to lift production rates, only two final products are now made and sold: lead concentrate and zinc concentrate.
CommodityProductUnits202020192018
Lead Concentrate kt 00004
Zinc Concentrate kt 00001.5
Silver Payable metal M oz 00
Gold Payable metal koz 00
Pyrite Concentrate kt 00

Operational metrics

Metrics2022202120202019
Tonnes processed 000000
Annual processing rate 0
Annual processing capacity 00
^ Guidance / Forecast.

Production Costs

Commodity production costs have not been reported.

Financials

Units202020192018
Capital expenditures M GBP 11.9  
Revenue M  ....  Subscribe  ....  Subscribe 3.2  GBP
Operating Income M  ....  Subscribe  ....  Subscribe
Gross profit M  ....  Subscribe  ....  Subscribe -2  GBP

Heavy Mobile Equipment

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Personnel

Mine Management

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Job TitleNameProfileRef. Date
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ContractorsYear
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Aerial view:

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