The Yandal gold project is a high-grade gold mine being developed approximately 83km from Leinster, Western Australia. Echo Resources owns the project and is developing it in two stages.
Bankable feasibility study (BFS) of the gold project was completed in August 2018, and certain pre-development activities commenced in September 2018. The project is expected to commence gold production in 2019.
The mine is expected to produce 785,000oz of gold over its mine life of 8.5 years. An estimated 6.5 million tonnes (Mt) of ore, grading 2g/t Au, will be treated in the first stage to produce 380,402oz of gold over four years.
Yandal gold project location
The Yandal gold project is located in the Yandal gold belt in Western Australia and comprises more than 1,600km² of contiguous and highly prospective tenement holdings.
The project hosts two deposits namely Julius and Orelia, which are proposed to be mined in two stages. The Orelia deposit is located within the Bronzewing district, while the Julius gold deposit falls within the Empire district.
Mining activities were conducted at the Orelia gold deposit from 1988 to 2013 and approximately 400,000oz of gold was produced from the existing open-pit from a depth of approximately 100m. Discovered by Echo, the Julius deposit is situated underneath a transported cover of 8m.
Yandal gold project geology and mineralisation
The Julius deposit is made up of a flat-lying, gold-rich laterite zone beneath indurated barren transported sands and silts. It hosts clay-rich supergene gold mineralisation and at depth. Primary gold mineralisation is associated with silica, quartz veining, and sulphide development.
The mineralisation of Julius is majorly focused on a shallow west-northwest dipping granite/greenstone contact, principally ultramafic lithologies.
Most of the mineralisation at Orelia is contained within deformed and altered tholeiitic basalts, along with dolerite units and sedimentary rocks. Formed as southerly plunging ore-shoots, gold mineralisation is identified at the convergence point of steeply-dipping transgressive faults and favourable lithological units, along fold hinges, and on lithological contacts.
Yandal gold project reserves
The proven and probable ore reserves at Yandal are estimated to be 14.9Mt, grading 1.7g/t of Au. It is estimated to contain 815,000oz of gold.
Mining and ore processing at Yandal
Conventional open-pit mining techniques using drill and blast with material movement by hydraulic excavator and trucks will be employed at Yandal. The mining fleet will comprise 120t-200t class excavators in a backhoe configuration, 95t class mine haul trucks, and other ancillary equipment.
The first stage mining at Orelia deposit will target the highest grades of gold and lowest mining strip ratios, while the second stage will aim at a significant cut-back of the open-pit in order to access ore at depth.
Echo proposes to mine the southern portion of the Julius pit to a depth of approximately 14m and extract shallow laterite ore, under the first stage. It also proposes to mine to a maximum depth of 60m to extract high-grade oxide supergene ore. The higher strip northern lobe of the pit is proposed to be mined to a maximum depth of 100m, in the second stage.
Ore from the two deposits will be processed at the Bronzewing processing plant with an annual throughput of 1.8Mt. The Bronzewing is planned to be refurbished at a cost of A$17m ($13.8m). It will employ conventional comminution and carbon-in-leach (CIL) with a modern gravity circuit and tailing thickener to produce gold.
Ore will be crushed in a two-stage crushing circuit, followed by semi-autogenous grinding (SAG)/ball milling with installed pebble crusher. The resultant product will pass through comminution circuit, which includes gravity gold extraction, followed by CIL and carbon elution circuits.
Infrastructure at Yandal
The Yandal project has existing infrastructure such as a 240-person mining camp, operational airstrip, power, water and telecommunication infrastructure, and a network of haulage and access roads. Other existing site infrastructure includes minimum tailings storage capacity of 17.5Mt, and site office and accommodation facilities.
The existing haul road from Bronzewing processing plant to the Julius deposit is currently being upgraded, which also includes 40km of new road.
Raw water is proposed to be collected from a licensed borefield and non-operation open-pits with pipelines in place.
The Bronzewing facilities will comprise an unsealed airstrip at Leinster, which is located approximately 70km to the south-west by road from Bronzewing.
Echo engaged MACA Mining and MACA Interquip, a subsidiary of MACA, for providing mining services at Yandal and for refurbishing the Bronzewing mill. MACA also invested A$1.5m ($1.09m) and acquired shares of Echo under a placement.
Echo Resources compiled the BFS with support from consultants, including CSA Global, Mintrex, Nagrom, ALS, Bureau Veritas Minerals, OMC, Coffey, and Widenbar and Associates.
PCF Capital Group prepared the financial modelling and also acted as debt adviser.