The Sekisovskoye deposit
The mineral rights at Sekisovskoye are held by a 100% owned subsidiary. TOO Sekisovskoye and the processing plant is held by the 100% owned subsidiary TOO Altai Ken-Bayitu.
The Sekisovskoye deposit is located at the village of Sekisovka , approximately 40 kilometres from the East Kazakhstan regional capital, Ust Kamenogorsk. The road from Ust Kamenogorsk to Sekisovka is sealed and provides the main route between Ust Kamenogorsk and Ridder (formerly Leninogorsk) and further on in to Russia.
Geology & Mineralisation
The deposit occurs in the northwest marginal zone of the 40 thousand sq.km Rudny Altai Palaeozoic metallogenic belt that occupies the eastern border of Kazakhstan and the Altaisky region of Russia. The mineral hosting intrusives are of late Devonian age.
Hambledon's extensive infill diamond drilling programmes within the upper horizons of the deposit have provided a higher confidence in the delineation of the gold zones, which better reflects the complexity of the gold distributions, in both shape and spatial continuity. Consequently, the number of mineralised zones has increased significantly: totalling 244 zones within the higher levels above the 250m elevation and a total of 307 zones for potential underground exploitation below the 250m level. True thickness of these tabular-like zones may change rapidly along strike and down dip, with a maximum delineated thickness of 45m, and the continuity of mineralisation may reach 700m downdip and 150m along strike. Most of these zones are parallel to sub-parallel within the hosting breccia pipe, with dips averaging 65 to 80 degrees northeasterly. It has now been shown that several of the “barren” igneous dykes within the hosting breccias can contain noteworthy gold levels and these have been incorporated into the modelling of the gold zones.
Gold is associated with hydrothermal alteration of the breccia zone matrix and also with hydrothermal sulphide veining. A high percentage of the gold occurs as intergrowths and free grains, with only a minor percentage locked within sulphides. Gold particles can be coarse, up to 0.4mm, and this contributes to an erratic grade distribution, in addition to the presence of unmineralised breccia fragments. CRS suggest that the presence of listvenite alteration indicates that the gold and silver mineralization may have emanated from hydrothermal solutions that developed from differentiated deep-seated ultrabasic magmas.
The deposit was discovered in 1833 by mining engineer, Ivan Zubarev, with surface mining taking place between 1833 and 1847, 1932 to 1935 and 1943 to 1946. From 1975 to 1986 a range of exploration work was carried out, starting from additional geological appraisal at 1:50,000 scale and finishing with preliminary exploration. Between 1978 and 1982 “AltaiZoloto” of the Ministry of Non-Ferrous Industry, KazSSR, mined the oxidised area of ore body 2. The open pit was excavated to a depth of 35m and a total of 3,406 kg of gold and 3,431 kg of silver was mined.
Starting in 2003, the exploration geology department of TOO Sekisovskoye carried out further exploration. From 2003-2005, 75 holes were drilled from surface producing a total of 8,245m of core, and in 2005-2006, 55 underground holes were drilled from the 441m underground level, producing 4,027m of core. All the samples underwent fire assay for gold content, and atomic absorption analysis for silver content at the internationally certified Alex Stewart laboratory in Kyrgyzstan
A computer model, using Datamine software, of ore-containing breccias and ore bodies at different cut-off grades was created and comparative reserve calculations made.
Within the licensed area, a detailed topographic survey was carried out at 1:1,000 scale.
This mineral resource estimate for the Sekisovskoye deposit has been prepared under the JORC Code. Mining operations commenced in mid 2006. The following resource table reflects the depletion of the original resource due to open pit mining activities and is taken from the 2009 Annual Report based on the work of Roger Rhodes, an independent geologist and Neil Stevenson, a director of the Company at that time. Both are considered to be qualified persons for the purpose of reporting resources under the JORC code and the AIM rules.
The underground resource is unchanged since the update reported in September 2006.
metal Au oz*
metal Ag oz*
|Open pit area||Indicated||5.39||1.6||277,268||2.5||433,231||0.5|
*Troy oz = 31.10348 grammes
(a) includes resources that have been defined beyond the current limits of the grade model. “Inferred” resources cannot be used for ore reserves until they have been upgraded.
(b) underground low grade material associated with high grade gold zones.
This ore reserve estimate of the Sekisovskoye deposit has been prepared under the JORC Code.
metal Au oz*
metal Au oz*
|Open pit area||Probable||3.06||1.60||157,614||2.45||241,331||0.5|
*Troy oz = 31.10348 grammes
The priority given to resolving production issues at Sekisovskoye restrained exploration activity in 2008 but a limited amount of exploration was carried out at Tserkovka. Though no significant discoveries were made, we plan to undertake bulk sampling of the surface exposure of its ore zones. By extracting and processing a total of 2,200 tonnes of ore at an expected grade of 2.45 grammes per tonne, we will determine the grade more accurately than is possible from sampling in this highly variable deposit. Former Soviet assessments showed higher grades and tonnes. If the bulk sampling exercise proves successful, further exploration will be carried out. In accordance with the terms of the subsoil use licence 30 per cent. of the 29 square kilometres of licensed territory at Tserkovka has been relinquished.
At Sekisovskoye, once we have established the initial underground decline, we plan to drill 183 holes totalling 24,000 metres from the 320m, 240m and 120m levels in order to upgrade the reliability of the resource estimate and as part of the project approval process. Test-mining will take place on orebody 11 from level 240m up to level 400m.
Our geologists have been researching other potential deposits which might be available in Kazakhstan, either by taking new licences from government or by contract with existing owners. Several potential targets have been identified and initial discussions have been held with the appropriate authorities. For the present, the government of Kazakhstan has suspended such negotiations generally, although we expect them to restart later in 2009.
The Sekisovskoye deposit consists of a steeply dipping series of lenticular zones striking NW/SE and dipping to NE. The mine planning has an open pit being developed from surface to a depth of 340 m above sea level to produce a pit of approximately 150 m deep. The underground is planned from the base of the pit to at least another 700 m deep.
With the commencement of processing in December 2007, the focus of the mining operation was to provide a steady supply of ore to the processing plant while also continuing the construction of the tailings storage facilities with the waste material mined from the pit.
The construction of the second stage tailings storage facility with the installation of the plastic lining was completed in August 2008. This will have sufficient capacity until around the end of 2009. Construction of the third stage, with capacity for around 1.5 years of tailings, commenced in late 2008 and was completed in September 2009. Construction of the final and largest stage will commence after the completion of the third stage in late 2009.
A second Atlas Copco L7 blasthole drilling rig was purchased and commissioned in May 2008. This machine was required to allow mining of the high volume of waste material planned to be mined in 2008 and 2009. In addition, we purchased a Hitachi Zaxis ZX200 fitted with a Montabert 900 rock breaker in June 2008. While the main task of this machine is to break the oversize ore generated from mining operations to a size that can be fed to the jaw crusher, it will also be used for small scale trenching operations.
The characteristics of the pit design are such that when the requirement for waste stripping is at its highest, the mine fleet cannot easily provide the increased tonnage that the upgraded process plant can now treat. The shortfall can be made up with lower grade marginal ore that will nevertheless provide a useful contribution to profits. In future years, this stripping requirement will fall, enabling a greater tonnage of ore to be mined. The ore grade is also expected to rise slightly with depth, giving a further boost to annual gold production
Infrastructure requirements for the project have proven to be minor as the deposit is located on the main road between the mining centres at Belousovka and Ridder, 40 kms to the north of Ust Kamenogorsk. Ust-Kamenogosk is the capital of the East Kazakhstan region that has been a mining and mineral processing centre for over half a century. Appropriately qualified staff, mining supplies, equipment and engineering facilities are readily available in the region. An adequate power supply exists from a nearby power grid and a site substation consisting of a 14Mw, 110/6 kV transformer and switch gear has been installed. Water and telephone connections are available nearby and an existing building was acquired and renovated for use as offices, kitchen facilities and laboratories.
The current open pit design consists of some 4.2 million tonnes of ore at a gold grade (diluted) of 1.2 g/t and a stripping ratio of 4.7:1, estimated to yield 213,352 ounces of gold and 366,280 of silver. This pit was deliberately curtailed in depth because of the benefit of keeping use of certain existing underground development which reduces the cost of mining from underground ore which would otherwise be economic from open pit. In the light of recent rises in the gold price this plan is being reviewed.
The initial planned mining rate of 850,000 tonne per annum gave a pit life of approximately 5 years. Mining operations are conventional drill and blast with excavator and truck haulage. Mining is carried out by Sekisovskoye’s own mining fleet as a detailed cost analysis conducted prior to commencement of operations showed there were considerable cost savings to be gained. The mining fleet consists of two Hitachi Zaxis 850H, 85 tonne excavators with a fleet of 45 tonne BelAZ 7547 mining trucks. The addition of a Kaneks EK450 45 tonne excavator in August 2009 has increased mine capacity which will enable mining operations to satisfy the enhanced capacity of the process plant. Drilling is carried out using Atlas Copco COPL7 drilling rigs. Ancillary mining equipment is a mixture of Russian and Chinese equipment.
The ore contains no environmentally deleterious components and environmental testing shows that there is no acid rock drainage issues.
Processing operations were carried out from January 2008 until mid February when the eluate boiler in the gold recovery circuit suffered catastrophic failure. The process plant was immediately shut down while we carried out investigations and repairs.
The processing plant restarted operations in late April 2008 following the installation and commissioning of a new boiler and heat exchanger. Initial throughput was affected by the spring rains on the clay-like material that had been mined from near-surface ore-zones, which hampered the material’s flow through the conveyor systems and tended to clog the sizing screens of the crushing plant. In winter, when temperatures frequently reach -40 C, freezing of the natural moisture in the ore caused further blockages and the widely fluctuating temperatures of spring and autumn caused freezing of rain-soaked dust to further slow down production. We attempted to modify the circuit to resolve these issues but were only partially successful until in late 2008 we decided to carry out a major upgrade of the crushing plant. Equipment was ordered and arrived on site in early 2009. In February 2009 we suspended the plant’s operations for a period so that all the new crusher equipment could be installed. Commissioning problems encountered in the start-up of the equipment in February and early March were quickly resolved and the crushing circuit is now operating well, with production consistently over 200 tonnes per hour, more than sufficient to supply the process plant with the required feed.
The failure of the crushing plant to produce sufficient quantities of material at an appropriate size limited milling operations throughout 2008. However, since the crusher upgrade in February 2009, we have gradually increased the tonnage feed through the process plant to the point where it is now able to operate well above the design capacity. Output will now be limited by the amount and grade of ore that the mine can supply.
In late 2007, AMC Consultants of Perth, undertook a study of the underground project which included the conceptual mine design, infrastructure requirements and equipment selection. The aim of the study was to develop an appropriate mining scenario for the Sekisovskoye underground project, undertake geotechnical investigations, produce a detailed mine design, develop a mine schedule, specify appropriate mining equipment and carry out a financial analysis of the mine. The study showed that it was feasible to develop an underground operation with an annual mining rate of up to 500,000 tonnes per annum using bulk mining techniques.
The study included a review of the total resource model for potential underground extraction, including areas above the 250 metre level, but outside the open pit design. In order to reduce the complexity of the study, only 34 of the larger gold zones were selected for detailed analysis and the results showed that these zones could be profitably mined under the proposed mine design. The remaining zones will be planned for as the mine progresses. The mine design was solely derived from the part of the resource that has been modeled in detail, which makes up a total of 3.3 million tonnes of both indicated and inferred resource at an in-situ grade of 5.2 grams per tonne. Some six million tonnes of inferred resource that has not been modeled in detail, together with the remaining smaller indicated and inferred zones, were ignored for the purpose of the study. The results can be expected to improve considerably in the light of further study and when drilling has been carried out to upgrade our knowledge of the inferred resource.
Based on the small part of the overall resource as described above, the mine plan indicates that 2.9 million tonnes are extractable from underground at an average, diluted grade of 4.7 grams per tonne, giving 433,371 contained ounces. Exploration carried out in the open pit zones by the Company has consistently shown grades of around 20 per cent. higher than previous Soviet era drilling had indicated and, if the same ratio is experienced underground where the Company has not yet carried out any drilling, the diluted grade can be expected to rise to some 5.6 grams per tonne
Work has commenced on the development of the required documentation to be presented to the Kazakhstan regulatory authorities for approval to commence underground mining. This requires our team of planning engineers and geologists to convert the current design into a format acceptable to the local authorities. Discussions with suppliers to source the required underground equipment to start development of the surface decline are ongoing, but outside contractors may be used initially. Previously indicated lead times for the supply of machinery appear to have been significantly reduced recently.
The total cost of mining, processing and administration is estimated to be some $64 per tonne, though this is partly based partly on the higher costs of operating in Australia . The total cash investment, including working capital has been estimated as US$22 million for the immediate development of the whole underground project. The Company is working on a development schedule that will proceed in stages to suit the approvals system operating in Kazakhstan and will use more local, former Soviet Union and Chinese equipment. Mine development is expected to commence with the construction of a surface decline to intersect the old exploration level at the 320 metre level (120 metres below surface). The likely up-front investment for the first stage, including working capital, will be US$3 million, which will be financed by the recent share placing in September 2009.
Output from underground is expected to be some 500,000 tonnes per year, while the remaining plant capacity will be filled with ore mined from open pit. On the basis of the expected uplift in grades, combined (underground and open pit) gold production will be over 100,000 ounces per year.
Drilling Results - 2005, 24 November 2005
Drilling Results - 2004, 19 January 2005