Apatite-staffelite ore flotation efficiency improvement using two-stage slurry thickening

The studies were performed suggesting that the cause of P2O5 losses during apatite-staffelite ores (ASO) treatment are due to non-selective flocculation of fine classes during flotation. When using strong flocculants, special preparation of condensed slurries is necessary, ensuring their deflocculation before the flotation process. A scheme and mode of preparation of fine classes for the flotation process have been developed, including thickening of the classification overflows using strong anionic flocculants and deflocculation of the thickened product before the flotation process with reagents-dispersants used in the basic flotation mode. A mode of preparation of slimes of ASO ores for flotation is proposed, including thickening of the discharge of the classification operation using the anionic flocculant “Praestol-2540”, conditioning of the condensed product with additions of liquid glass and caustic soda in a ratio of 1 : 1, dilution and re-thickening of deflocculated slimes, consolidation and flotation thickened sludge and sand. The big laboratory tests have shown that the application of the developed regime provides a total increase in the extraction of P2O5 from ore from 70,1 to 71,5 % with an increase in the P2O5 content in apatite concentrate from 37,1 to 37,8 %, which makes the developed technology promising for processing refractory ASO at Kovdorsky GOK.

Geological structure and localization of mineralization at the Moryanikho-Merkurikhinskoye ore field

The paper discusses the lithological and facial features of the terrigenous-carbonate (biohermic) ore-bearing geological formation of the Moryanikho-Merkurikhinskoye ore field (Yenisei Ridge), which hosts stratiform lead-zinc deposits in carbonate strata. Ore-hosting lithofacies and their paleostructural position are characterized. Based on the previous studies, as well as the author’s own materials obtained as a result of field work, the main favorable lithological, facial and structural factors for hosting Moryanikhinsky-type stratiform lead-zinc mineralization are defined: the presence of paleodepressions within the shelf zone; development of carbonate rocks – dolomites, stromatolite dolomites and limestones, which are biohermic structures on the slopes of paleo-uplifts; the presence of an admixture of tuffaceous material in terrigenous rock varieties. The influence of tectonic faults on the formation of ore deposits and the morphology of ore bodies is indicated. The main types of ores of the Moryanikho- Merkurikhinsky ore field, as well as their mineral composition are described. The paper discusses the main ore types, as well as their mineral composition typical of the Moryanikho-Merkurikhinskoye ore field. The largest and well-studied lead and zinc stratiform Moryanikhinskoye deposit and Merkurikhinskoye ore occurrence located within the ore field are briefly characterized. The Moryanikhinskoye deposit is a typical example for searching for stratiform deposits of lead and zinc in the carbonate strata of the Angara-Bolshepitskaya mineragenic zone, which is of practical interest in developing predictive prospecting models of deposits and improving the efficiency of prospecting.

Basites of Vilyui-Markhinsky dike belt (Vilyui paleorift) and their relations with Nakyn field kimberlites

The Vilyui-Markhinsky dike belt (VMDB), which was formed as a result of Devonian rifting on the eastern margin of the Siberian Platform, is the marginal part (area of scattered rifting) of the Vilyui paleorift structure. The Nakyn field is located in the central part of the belt, but is controlled by an independent system of NNE-trending tectonic faults. The belt dyke intrudes the Nyurbinskaya kimberlite pipe. On their contact, specific breccias were formed resulting from the interaction between degassing products of basic magma with kimberlites. The typical zonality of the dyke endocontact indicates a later dyke introduction. Dolerite dikes thermally metamorphosed breccias in which high-temperature neoplasms of andradite, Al-lizardite, and clinochrysotile were generated. VMDB basites represent a single association, in which two series of rocks are distinguished: moderate-titanium (TiO2 ~ 2.5 wt. %) with normal alkalinity and low P2O5 content, and high-titanium (TiO2 ~ 4.4 wt. %), occasionally with moderate alkalinity. The differences in the dike composition are insignificant and are the result of natural variations in the composition of individual bodies. 40Ar/39Ar dating of the VMDB basites, the method characterized by the best results convergence, shows that they formed in a narrow timeframe corresponding to the Upper Frasnian – Famenian stage of the Upper Devonian (368.5 to 376.3 Ma). The location of the Nakyn field basites and kimberlites is controlled by faults of various types, orientation and age. Kimberlites formed first, and VMDB intrusions followed.

Geology and pyrite-polymetallic mineralization of the forecasted Limonite deposit, Rassokhinsky ore cluster (Yenisei ridge)

The development of Russia’s largest Gorevskoye leadzinc deposit (Gorevsky GOK, Novoangarsky OK) will depend on promising deposits of the Angara polymetallic ore region, in particular, those of the Rassokhinsky ore cluster. Based on the analysis of geological and geophysical information of previous and current studies, a major Limonite pyrite-polymetallic (massive sulfide) deposit is forecasted within it. The main lithological and stratigraphic criterion for the localization of ores is determined by their confinement to high-carbon black quartz-sericite schists of the upper subformation of the Potoskuy suite of the Upper Riphean. In the top of this pack, layered and massive pyrite-polymetallic ores, 70– 140 m thick, are localized. Based on PPA data, lead and zinc content in core varies from fractions of a percent to several percent, based on the ICP-AES method: 0,1– 3,7 % Pb, 0,1–6,4 % Zn, Pb : Zn ratio is 1 : (1–10).

Gold and silver accessory minerals in ultramafites of the Kyzyr-Burlyuksky ultramafic massif (Western Sayan)

The study focuses on gold and silver accessory minerals (native silver, cuprous gold, luanheite (Ag3Hg), unspecified mineral phase (Cu,Ag,Hg), first diagnosed in dunites and apodunite serpentinites of the Kyzyr-Burlyuksky ultramafic massif, which is part of the Kurtushibin ophiolite belt of Western Sayan. The revealed ore minerals are mainly observed in the form of single hypidiomorphic, irregular microscopic precipitates (0.5– 3.0 μm) mainly inside magnetite, much less often in grains of avaruite. Typomorphic and chemical features of ore minerals, their natural setting in rock-forming silicate matrix are characterized. Formation and concentration of these accessory minerals is associated with superimposed low-temperature transformation (hydration) processes affecting original ultramafic rocks. At the same time, the presence of luanheite and an unnamed phase (Cu,Ag,Hg), along with the previously identified potarite (PdHg), is probably evidence of low-temperature conditions of mineral formation during the manifestation of epigenetic processes of serpentinization (lowgrade metamorphism) due to solutions enriched in mercury. The source of such solutions could be gabbro intrusions that penetrated later into the main ultramafic body.

Rare metal-polymetallic mineralization of Koshmansay ore field (Eastern Uzbekistan)

The Koshmansai ore field is located in the southern part of the granitoid Chatkal batholith, in its apical ledge and exocontact zones, in the Koshmansai river basin. The host environment of the granitoids is Lower Carboniferous carbonate rocks, which were primarily affected by intensive skarnification. Sedimentary-metamorphic and volcanics rocks and granitoids constitute the geological structure of the skarn rare-metal-polymetallic Koshmansai deposit. In the distribution of ore-forming and associated elе- ments in the mineral phases of skarn orebodies, their morphogenetic type plays a certain role. Thus, in bimetasomatic skarns, minerals accumulate more Cu, Zn, Ni, Te, Tl, Ge. In infiltration skarns, these are Ag, Pb, Bi, Cd, Sb, Co. Sulfide polymetallic mineralization in skarns is associated with quartz and calcite. The Koshmansai ore field has a distinct geochemical zoning, which can be subdivided into the Koshmansai rare- metal-polymetallic deposit at the upper levels of the ore field and the Nizhnekoshmansai rare-metal-copper ore occurrence at its lower levels. Nevertheless, orebodies formation proceeded in a similar thermodynamic environment, in the conditions of upper shielding at low temperature gradients, which makes it possible to consider the ore field as a single geochemical anomaly. The vertical geochemical zoning of ore-forming element halos determined by their concentration at the lower section levels of the Koshmansai deposit skarn orebodies suggests the expansion of its prospects in depth.

Objective method for analysis of mineral resources supply on the example of Russia

A forecast of nonfuel mineral production in Russia is considered, based on the integration of the expected life of specific deposits currently exploited and developed. It is shown that mineral safety is fully ensured for copper, nickel, lead, tungsten and tin, whose reserves are sufficient for their extraction, at least at the current level, for 40–50 years and there are real prospects for its significant growth. The sufficiency of other minerals is much lower: for molybdenum and chromium, it is limited to about 30 years, and the extraction of zinc and uranium in Russia may significantly decrease in 20 years. The situation is more difficult with the most liquid solid minerals, like gold and diamonds. The commissioning of mining enterprises at the developed gold deposits can ensure a rapid growth in the production of the precious metal in the coming years. However, at the beginning of the next decade, the resource base depletion of the Olimpiada field and a number of other exploited deposits is predicted. The projects currently implemented for the development of new fields do not compensate for the lost capacity. This may account for a long-term (until the beginning of the 2050s) decline in the Russian gold production, which may be halved against the current level by the end of this period. Such a scenario can only be avoided with the intensification of geological exploration in the coming years. The earlier decrease in the number of diamonds mined in Russia, associated with the depletion of reserves of exploited pipes, is predicted (since 2025). Unless new deposits are discovered and developed, the domestic production of precious stones will steadily decline and, in the 2040s, may be reduced fourfold.

X-ray computed tomography study for drill core of the Drazhnoe orogenic-type gold deposit (Sakha (Yakutia), Russian Federation)

Orogenic gold-quartz deposits have a clear structural control and are accompanied by wallrock metasomatic alteration. However, in detailed modeling of such deposits, there is often a mismatch between the structural plans for high-grade ore zone distribution and metasomatite zones, and the latter are not always associated with faults. This is explained by the evolution of the hydrothermal process and the pulsating nature of the development of the territory. In the early stages of the mineral deposit study, it is very important to reliably determine the distribution of ore zones, since the correct targeting of the drilling program and the economic deposit assessment depend on it. The problem can be solved using the method of X-ray computed tomography (СТ) in the core study. This paper presents the methodology of studying fullsize core samples of gold deposits by using CT. A core sample characterizing the central part of ore body of Drazhnoye deposit (Tarynskoye ore field, Republic of Sakha (Yakutia)) was used as the study material. The sample studied was scanned by a SIEMENS Somatom Perspective tomograph at two energies (80 and 130 keV). As a result, a detailed three-dimensional stereological model of the core was obtained, which made it possible not only to study the distribution of ore minerals in the volume of the entire sample, but also to identify vein bodies of different ages, as well as to study their morphology and trace the distribution patterns of ore mineralization in them. Based on the study results, we can offer a preliminary interpretation of ore mineralization and vein formation sequence.

Geological and geophysical criteria as indicators of promising areas for diamond prospecting

The developed complex of geological and geophysical criteria is shown, which is recommended for use in localizing areas for setting up prospecting works on primary diamond deposits.

Ratio of structural impurity distribution in diamond crystals and kimberlite pipe diamond potentiak (case study of Arkhangelsk region and Yakutia)

IR spectroscopy was used to compare diamonds from 12 pipes, Arkhangelsk region. Based on positive correlation between average N and H values in diamonds from various deposits, it was found that crystals from low-grade diamond pipes are relatively enriched in hydrogen compared with diamonds from Lomonosov and Grib deposits. In terms of structural impurity distribution, Arkhangelsk deposit diamonds differ from Yakutian diamonds; it could be due to various composition of compared diamonds’ source matter and thermodynamic conditions of their growth. It is shown that hydrogen is a negative factor of diamond potential in both Yakutian and Arkhangelsk diamonds. This can partly be explained by impuri-ty blocking effect on diamond crystal growth.