Bobrikovo mine is located in Eastern Ukraine in the Luhansk (Lugansk) Province. Bobrikovo gold and silver project has a JORC Code compliant resource of 3.3 million ounces of gold and 16.3 million ounces of silver. In addition to the classified mineral resource Bobrikovo has a substantial exploration potential. The oxidised mineralisation of the Bobrikovo deposit begins at the surface and extends down to 40-50m. Fresh rock mineralisation occurs from the depth of 40-50m down to at least 3000m.
Bobrikovo has been mining and stockpiling oxide ore on a campaign basis and has commenced the development of the processing plant and other mine infrastructure. It is planned to develop the oxide and transition zones of the deposit as a simple open cut mine. Development of the fresh rock zone is anticipated to use a low-cost sub level caving method. Once the plant has been constructed, part of the mine output is planned to be processed into concentrate using low-cost gravity-based plant. Bobrikovo is targeting oxide zone operating costs around $500/oz. The company has received proposal to sell ore to a third party for processing through their metallurgical plant. The sale of ore will potentially allow the company to generate early cash flow without cash outlay and to build the processing plant using retained earnings from sale of ore.
Project is located within a large intra-continental Phanerozoic structure that extends from southern Europe east to Central Asia. This structure hosts several world-class gold mining operations including Muruntau, Vysokovoltnoe, and Bakirchic. The tenor and style of mineralisation at Bobrikovo is similar to 170 million ounce gold deposit at Muruntau in Uzbekistan and to multi million ounce Sukhoi Log deposit in Russia.
Bobrikovo deposit is located within a structure that strikes 11km by 2.5 km. The deposit occurs on the intersection of deep fault zones. Mineralisation is controlled by NW-NNW trending anticline hinge, and occurs as concordant and discordant quartz-carbonate tension veins and stockworks. Host rocks of the Nagolny Kryazh comprise two structural stages: the lower, Precambrian, and the upper, Phanerozoic. The lower structure comprises deformed sequence of gneisses and crystalline schists. Precambrian basement is overlapped by 3km- thick sedimentary rock sequence. Ore zone is 2.5-3 km long and 0.9 – 1km wide.
Metallurgy Tests Results
Independent test work by accredited laboratories has shown good recovery of gold from both primary and oxide ores using variety of methods including gravity, cyanidation and heap leach. The summary of test results is included below:
- Hydrocyclone extraction recovery 72-79%
- Gravitational extraction recovery 62%
- Gravitational concentrate recovery 46-81% (average 60%) tail cyanidation recovery 90%. Total extraction after gravitation and cyanidation 94-98%
- Cyanide leaching of test sample of 10k tons of ore recovery: 92,03%
- Heap leaching recovery 92%
- Concentrate obtained by KNELSON thickener recovery 77.5%, concentrate with Au content 473g/t
- Gravity table recovery 63-76%
- Concentrate obtained by KNELSON thickener; recovery: low grade ores 40-50%, high grade ores 90%.
- Combined gravitational-cyanidation recovery 90-95%
Muruntau gold deposit in Uzbekistan is the world's largest gold deposit with production of 2Moz Au per annum. The ore reserves and resources at Muruntau (including historical production) is about 170Moz of gold. It is also world's largest open pit gold mine, The open pit measures about 3.5km by 2.5 km and extends to a depth of 350m. Ore is mined from an open pit with dimensions of about 2,500m x 3,500m, and 300m deep. Final pit depth is planned to be 650m with the mineralisation known to extend to a depth of at least 1,500m. Long term plans are to mine from underground. Gold is free milling with variable grain size and minor gold associated with sulphides, primarily arsenopyrite. Muruntau processing plant treats ore with an average head grade of 2.4 g/t Au at the rate of 2.2kt per day. The processing circuit includes a gravity circuit.
There are many similarities between Bobrikovo and Muruntau deposits, but mineralisation at Bobrikovo is closest to Sukhoi Log gold deposit in Russia. Mineralisation at Bobrikovo occurs at the intersection of deep fault zones controlled by NW-NNW trending anticlinal hinge and occurs as discordant and concordant quartz-carbonate veins and stockworks.
Sukhoi Log gold deposit mineralisation is similar structurally and in style of mineralisation to Bobrikovo deposit. Sukhoi Log's mineral reserves at a cutoff grade of 1 g/t Au are 384Mt with average grades of 2.6 g/t Au for 33Moz. Additional resources include 165Mt at 2.1 g/t which could be converted to reserves and developed into an open pit operation. 205Mt at 0.8 g/t Au sits as a low grade halo around the higher grade mineralisation.