Lindsays Gold Mine
Ability to immediately re commence production from existing open pits with the previously planned underground mining.
The 2015 Parrot Feathers underground resource identified a high grade option of 401kt @ 4.2g/t Au
Resource model and mining studies to be re-done at current price inputs.
65km North North-East of Kalgoorlie WA, the Lindsay’s Gold Mine is located on the Archaean Kalgoorlie Terrane within the Eastern Goldfields Province. The province is estimated to have produced 120.0m+ oz of gold.
Lindsay’s Gold Mine has been in operation during various times throughout the nineteenth century, with production totalling some 4kt at an estimated grade of 19g/t gold. Production from the Lindsay’s Find area during the 1930s is reported as 950t at 3.0g/t gold. In 1987, a further 15t was mined at a grade of 15.4g/t. Initial mining in the Trial Pit area was reportedly underground with 1,361t at 7.0g/t gold being produced between mid-July 1987 and the end of January 1988.
In February 2012, ORElogy undertook a pre-feasibility assessment on the updated geological resource for the Lindsay deposit. The study highlighted that the project was viable and had the capacity to generate significant cash-flow over a short mine life. The resulting reportable ore reserve generated stood at 664kt of Probable ore at 2.19g/t. The associated waste was ~9,018kt, resulting in a strip ratio of ~13.6:1.
Open pit mine production at Lindsays by KalNorth commenced in January 2013 with development of three open pits, the largest being the Stage 2 Pit which hosts the Parrot Feathers lode. Mining ceased in August 5 2013 after the production of 138,229 tonnes of ore grading 1.93gpt which was hauled to and processed at Saracen Mineral Holdings Carosue Dam operation located some 75km to the east.
Geology & Mineralisation
The Lindsay’s Field lies in the Archaean Kalgoorlie Terrane within the Eastern Goldfields Province of the Yilgarn Craton. It covers a broadly northwest trending folded and deformed sequence of predominantly basalt and dolerite with intercalated metasedimentary units comprising black shale, arkosic sandstone and pebbly grits, which is intruded by granodiorite. The project geology is dominated by a north north-west (NNW) trending, very-steeply dipping, tightly closed fold in the north east and a large granodiorite intrusive in the south west.
Three main northwest trending gold mineralised structures trend through this folded sequence of rocks and granodiorite and known as the Eastern Structure, the Central Structure and the Western Structure.
Gold mineralisation is predominantly found within quartz veins hosted in the granodiorite and mafic country rocks. The veins are usually 1-2 meters wide and predominantly shallowly dipping between 15-25 degrees to the southwest. Gold grades within the quartz veins appear higher within the mafic country rocks compared to the granodiorite.
As there are both Open-Pit and Underground JORC compliant resources mining at the Lindsays Gold Mine may comprise multiple satellite open pits and an underground deposit known as the Parrot Feathers Deposit.
Open pit technical work was undertaken in 2015 which Identified 3 open pit resources namely Trial pit, LC4 and LC 1, comprising approximately 100,000 tonnes of ore at an average 2.46g/t Au for 7,900 ounces. The Trial Pit comprising 25,000t at 2.2g/t Au for 1,800oz is the most advanced and only requires grade control drilling prior to production. The LC4 and LC1 pit comprise 11,300t at 3.85g/t Au for 1,400oz and 60,000t at 2.45g/t Au for 4,700oz respectively. These were not mined as focus was shifted to the underground resource due to decreasing gold prices. Updated surface optimisation is currently underway utilising current financial inputs along with an updated JORC resource and this should increase the pits available for viable extraction of the resource.
A scoping study was undertaken on the Parrot Feather resource in 2016 and the study showed robust results both technically and economically which warranted advancing the project to full development. Based on the initial resource model, a mine design was drawn up that maximises decline development in footwall lodes and uses conventional narrow vein mechanised mining to extract the orebody. Metallurgical test work was carried out and showed that Parrot Feathers ore has an expected recovery of 90.9%, is hard with a bond work index of 16.5kWhr/t and requires oxygen addition to maximise recovery.