In the Tenkinsky district of the Magadan region is one of the largest gold deposits. It belongs to the Yano-Kolyma gold ore province . The Natalka gold deposit in the Magadan Region is located between the Glukhar and Geologichesky streams, in the Omchak River Valley.
The beginning of development
The Natalka gold deposit was discovered in 1942. Geologist Aseev discovered 2 gold-bearing streams. After a while, they were named after the children of the geologist: Natalka and Pavlik. From them came the names of deposits.
In 1945, the Matrosov Mine was established to operate the pool. It was part of the Tenkinsky mining department.
Reserves of the Natalka gold deposit
In 2015, revaluation of reserves was carried out. This world-class gold mine was in third place in terms of proven and probable production. After revaluation, reserves are estimated at 319 million tons with a content of 1.6 grams per ton.
The identified, estimated and estimated volume of mineral resources is 777 million tons with a content of 1.5 grams per ton. In comparison with the estimate for 2011, ore volumes decreased by approximately 301 million tons (28%), the gold content decreased by 14%.
Project implementation
In 2003, shares of OAO Matrosov Mine OJSC were put up for an open auction (38% federal package). The buyer was Norilsk Nickel, which gave over 1 billion p. This amount exceeded the starting 13 times.
In 2004, Polyus Gold CJSC became the full owner of more than 29 thousand ordinary shares (38% of the authorized capital). In July of the same year, preparations began for changes in field development technology, and production was suspended.
Until 2004, mining was carried out by the underground method. Ore was processed using a gravity-flotation system with almagamation of gravity concentrates and hydrometallurgical processing.
Despite the large volume of reserves, production at the Natalka gold ore deposit did not exceed 1.5 thousand kg / year. For all the time since the beginning of its commissioning, 93.2 tons were recovered.
Additional intelligence
It was carried out at the Natalka gold ore deposit from 2004 to 2006. The purpose of the additional exploration was to clarify the morphological composition of the ore body during exploratory conditions that corresponded to high-performance open-cast mining.
More than 120 m of core wells, 655 thousand m3 of ditches were drilled. In total, more than 44,000 samples were taken.
In December 2006, reserves of the B + C 1 + C 2 category of 1,500.8 tons of gold were approved with an average grade of 1.7 grams per ton. Beyond the contour of the quarry, off-balance reserves were also taken into account, the volume of which amounted to more than 309 tons.
Audit 2007
In September, Micon International Ltd. completed the stock assessment. According to the audit, the reserves amounted to 2.1 thousand tons with a gold content of 1.13 grams per ton.
The assessment was based on the estimated gold price of $ 625 per ounce, dilution of 7%, cut-off grade of 0.3 / ton, and average recovery of 87%.
The Natalka gold deposit is second only to the 2 largest basins in terms of reserves: Grasberg (located in Indonesia) and Muruntau (in Uzbekistan).
A new stage of development
It began in 2013. During this period, the most significant event was the implementation of a complex logistics operation to deliver the mills to the construction site. In July 2013, land management was completed, the construction of the factory and the arrangement of the quarry began. In August, the installation of technological equipment began.
In mid-November, the largest mill in the world is being tested at the field. Its capacity should have been enough to process about 40 million tons of ore. Along with the launch of the mill, the laying of a kilometer tunnel began. It was supposed to be used to transport ore to a gold recovery plant.
Second revaluation
It was held in November 2014. ZA Polyus Gold announced a decrease in reserves estimates by more than 50%. In this regard, the launch of the Natalka GOK was postponed indefinitely.
In 2015, a decrease in reserves to 504 tons was announced.
Stock Unconfirmation Problem
In reconnaissance, bi-directional errors occur. Some of them underestimate the gold content, and some overstate. With the coincidence of errors of a different sign, a kind of compensation occurs. As a result, the average exploration rate coincides with the mining parameters. Deviations can be significant. However, with their compensation, no one has any problems: neither the scouts nor the miners.
However, the situation at Natalka and some other gold ore deposits was somewhat different.
The main understatement is due to technical errors. Because of them, there is a loss of part of the gold during the selection and subsequent processing of samples. With high technical deviations and low random variability of the distribution of gold content, the balance of errors is in favor of the mining enterprise. In this case, the average actual amount of gold is higher than the figures obtained during exploration.
The overestimation of the content is also caused by errors arising in the process of contouring ore bodies, which are characterized by high random variability. These deviations depend on the network density and sample size. They are called methodological errors. At their high rate, the area, size and shape of the ore bodies are distorted. As a result, this affects the results of operation. Gold is actually present in the quarry, but it is not where the intelligence determined.
Options for solving the problem
To correct the current situation with non-confirmation of reserves, it is first necessary to provide for the determination of the deviation indicator of the average content and contouring during detailed exploration of deposits with a high degree of variability. This will allow you to plan the necessary costs at the design stage, to adjust the methodology of operational exploration and additional exploration, to provide sorting to increase the gold content in ore, etc.
As for the Natalka field, it should be noted that from the technical side there are no complaints about the quality of exploration and testing. This means that technical errors were negligible.
At the same time, the Natalka deposit has a complex structure. Ore bodies containing large gold are found in it. Under such conditions, the network density and the used mass of samples were insufficient. As a result, there were high errors in constructing the contours of bodies. The deviation balance was ultimately not in favor of the miners.
Production modernization
In early June 2015, a new ore processing method was introduced. In 2017, the planned launch of an enrichment plant.
In 2015, in September, Polyus Gold CJSC concluded an agreement with the Chinese company China National Gold Group Corporation on the procurement of materials and industrial equipment, design and construction of production facilities. At the same time, the management of the mining company was considering the option of incorporating the corporation into the share capital of a joint venture with Polyus-Gold to develop the field.
At the beginning of November 2015, the construction of the tunnel was completed, which connected the quarry and the gold recovery factory. It took 2 years to build a 970-kilometer tunnel. In February-March 2016, the company planned to begin installation of the conveyor complex. With its help, direct transportation of ore to the factory should be carried out.
In December 2015, according to the presidential envoy to the Far Eastern Federal District, Yuri Trutnev, about 10 billion budget funds should be allocated for the construction of a mining and processing production enterprise at the Natalka field. Private investments should have amounted to more than 88 billion rubles. It is likely that financing will allow the production process to restart. At the same time, most likely, in the development of the field, innovative technologies and modern equipment will be used.