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By I. Y. Titov, Victor D. Samyguin, A. Y. Nikitin

"It is suggested that improvement of separation process efficiency in machines and circuits of selective flotation should be based on application of the principle of technology individualization (PIT). This principle is grounded on the following provisions.The mineral composition of ores is used to establish the correlation between the selective reagent mode and the individual value of hydrodynamic conditions of flotation machines together with individual structure of the process flow diagram. The individuality of all sorts of particles identified by methods of process mineralogy was characterized by their distribution according to the rate of flotation (or spectrum). The spectrum identification is carried out by modeling and by experimental and computational method on the data obtained on various types of laboratory flotation machines.The computer-aided test is used to determine the optimal fraction distribution, which reaches the highest possible level of concentration data. The direction of hydrodynamic factors action on concentration data is estimated based on comparison of design base and experimental spectrum. The improvement of separation efficiency in devices is achieved in special-purpose flotation machines (SFM) the design of which provides optimization of hydrodynamic regime in spatially isolated zones. It is demonstrated that the main parameter of SFM operating mode individualization is the rise rate of bubbles going from the chamber into the froth. During this time the composition of particles optimum for separation is formed on its surface. Additionally, it is necessary to coordinate in the zones the residence time of pulp and foam streams with the air consumption. The improvement of separation efficiency in flotation process flow diagrams may be achieved by making several cascades with SFM installed in them. The individual effective structure of the scheme for a definite ores material composition depends on the ratio of particle varieties in the spectrum and is revealed by modeling."

Jan 1, 2018

A new short combined flow sheet including high intensity magnetic separation and flotation for a rare earth ore in Maoniuping deposit, China has been investigated. Massive conclusive results demonstrate, that it is critical to separate the ore by high intensity magnetic separation prior to flotation for tons of slimes and nonmagnetic gangue existing. The vital technological parameters affecting flotation have been studied in detail. Modified hydroxamic acid is an efficient collector for bastnasite flotation because of its high selectivity. Flotation results also indicate high temperature that play an unfavourable role on the recovery as well as the grade of bastnasite concentrate, when the rare earth ore is floated with modified hydroxamic acid and sodium silicate depressant. Bastnasite concentrates, averaging over 65 percent REO at an overall recovery of 82-84% is achieved by the new beneficiation technology. Keywords: bastnasite, REO, magnetic separation, flotation, chelating collector, desliming

Sep 1, 2012

By A. Bahrami

Andalusite, silimanite and kyanite are polymorphs of aluminosilicate known as kyanite group. Minerals of this group are used in refractory. Sarband andalusite deposit is located in Markazi province in Iran. Mineralogical studies showed that the main minerals of this sample are andalusite (5%~10 %), mica, quartz and feldspar. Processing of the samples was carried out using two sizes, i.e. +500 µm and -500 µm. In the processing of +500 µm scrabble test was carried out on -4750 +500 µm and -2380 +500 µm. For -500+300 µm shaking table and magnetic separation were applied. For -300 µm fraction, flotation was carried out. The results of this tests showed that the processing of Shazand andalusite was not possible, because silica and iron impurities were diffused inside the andalusite mineral grains.

Jan 1, 2014

By Robin J. Batterham

Alumina demand is steadily climbing around the world and is likely to continue to do so for many years. In such a commodity industry, the question arises as to what effort should be expended on innovation, given that for an individual company, the drivers of change are cost and quality as the market demand is essentially assured. This is of course a long-term view. The current conditions are less attractive. In this presentation, we review the broad issues that are considered targets for collaborative development by the industry as recently updated in the alumina industry roadmap published by the International Aluminium Institute in 2010. While they cover areas such as ?mine rehabilitation, residue management and use, alumina production from high sulfur bauxite, bauxite beneficiation, energy efficiency and alternative technologies for alkali and alumina recovery from bauxite residues,? it must be remembered that each refinery is different in terms of the feed material and the circumstances of waste disposal. Of particular interest is the more competitive area of breakthrough technologies. In the presentation, we will consider a range of opportunities that could transform the industry, from relatively near term possibilities such as bauxite activation through possibilities to eliminate crystallization as currently practiced to complete alternatives, such as the use of hyperaccumulating plants. Against this optimism, some of the realities that hold back breakthrough innovation will be presented for discussion.

Sep 1, 2012

By Xiao Ni

Alkyl hydroxamic acid was shown to be a suitable collector for the flotation of pyrochlore from carbonatite niobium oxide ores. In the direct batch rougher flotation from the ore without desliming, over 85% of the pyrochlore can be recovered at about 30% mass pull. Cleaner flotation tests showed that the rougher concentrate can be upgraded. The adsorption mechanisms of octyl hydroxamic acid (OHA) were studied by using high purity pyrochlore and calcite mineral samples and employing analytical measurements such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and UV/VIS spectroscopy. FTIR showed a shift of the vibrational frequencies of the carbonyl group in hydroxamic acid after adsorption on pyrochlore and calcite, and the shift was more pronounced on pyrochlore. XPS results indicated a lowering of the binding energies (chemical shift) of Nb3d5/2 and Ca2p3/2 electrons on pyrochlore, and the lowering of the binding energies of Ca2p3/2 electrons on calcite, again with the shift being more pronounced on pyrochlore. The results indicated hydroxamic acid formed stronger complexes with pyrochlore than with calcite. Adsorption isotherms indicated that OHA adsorbed more on pyrochlore than on calcite at low concentration. At high concentrations, the adsorption densities on both minerals were similar. All results explained the observed selectivity of the reagents in the flotation of the carbonatite niobium oxide ores.

Sep 1, 2012

By Luis Bergh, Iván Rojas, Juan Yianatos, Luis Vinnett

"At present, flotation rate characterization follows standard measurements to identify the overall flotation performance looking at the feed, tailings and concentrate in flotation cells or banks. This classical approach does not take into account the evolution of the true collection rate down the flotation banks explicitly. The potential for identifying the impact of the mineral characteristics (size and liberation) as well as the effect of different manipulated variables (reagents, froth depth, gas dispersion) on the true flotation process remains hindered. Top-of-froth (TOF) measurements, which consist of sampling the first layer on the froth surface, have been used to characterize the mineral collected by true flotation in rougher banks. The information provided by TOF samples allows evaluating the floatable mineral evolution (grade, particle size, liberation) down the bank. In this work, an indirect approach to estimate the flotation rate along rougher flotation banks is proposed. The new approach is based on the decreasing of collected mineral grades (on top of froth) and the feed characteristics. Flotation rates per liberation classes were used to reconstruct the TOF grades from the feed information. This approach requires a simple froth surface sampling, without constraints typically observed during mass balance surveys and uncertainties on the mineral recovery estimation. The proposed methodology was successfully applied at industrial scale using TOF measurements together with QEMSCAN information."

Jan 1, 2014

By Gulsen Tozsin, Ekrem Kalkan, Taskin Oztas, Elif Agirman Akturk, Ercument Koc, Ali Ihsan Arol

Marble wastes are generated by quarries (marble quarry waste-MQW) and processing plants (marble cutting waste-MCW). The large amount of marble wastes is becoming serious problem for industry and environment because of discarded into rivers and lagoons, without any treatment. Marble wastes can cause environmental problem and economic loss if the waste is not used. However, this type of wastes has a good potential to be used as an amendment for the neutralization of acid soils. In this study, MQW and MCW were applied to an acid soil at different rates and their effectiveness on neutralization was evaluated by a laboratory incubation test. The results showed that soil pH increased from 4.71 to 6.36 and 6.84 by applications of MCW and MQW, respectively. It was suggested that MQW and MCW could be used as soil amendments for the neutralization of acid soils, and thus the negative impact of marble wastes on the environment could be reduced.

Jan 1, 2014

By Lei Wang, Qi Zheng, Xiao-kui Che

"The wastewater emitted by gold chemical industry contained vast of different heavy metal ion, such as Zn, Cu and Ni etc. Among them Zn is the main ion in the waste water which causes the serious environment pollution. A method of preparing a kind of resin which is used for the removal of Zn by magnetic adsorbent was developed and was applied in practice. This adsorbent is a chitosan made of a kind of Fe3O4-chitosan modified by epichlorohydrin. The adsorption capacity of the absorbent and it was concluded that under the laboratory conditions, the maximum adsorbing capacity of this adsorbent could be 287.58 mg/g. The absorbent was also applied in the wastewater emitted by a gold industry in Shandong province. Its performance was tested and the result showed that the concentration of Zn ion in the wastewater was reduced from 0.58 mg/L to 0.0174 mg/L. What is more, the adsorption rate could be more than 97% when the dosage was 100L/m3 after adsorbing for 1h. KEYWORDS Selective, preparation, laboratory experiments, industry experiment, comparation INTRODUCTION Currently, most gold chemistry use cyanide to leach gold ore. Many different metals participate to this reaction besides the gold ion in this processing, so that the composition of the water is very complex. The waste water emitted by gold chemistry industry contains large amount of heavy metals. Definitely, if it was discharged without any treatment, the water would threaten the environment. The recuperation of any ion in the water would mitigate the pollution. Ion exchange resin, which is an effective material to do the water treatment with low cost, became widely applicated in this field [Yu-jiao Wang,2013]. Different kinds of resin were developed and the influence factors such as pH, adsorption properties and selectivity for different ions were investigated [CA Cruz et al,2018; PawanKumar et al.2016; Y Zhang, et al,2010; and ShengingSun, Aiqin Wang, 2006;]. The waste water mentioned in this article has a high Zn concentration, so a magic resin for Zn adsorption selectively we designed was used to manage this water. And the recovery of Zn could not only contribute to pollution abatement but also a best way to settle a dispute to the short of Zn resource. So the article mainly describes the preparation and the application of a kind of magnetic adsorbent used for the removal of Zn both in laboratory and industry. The aim of this article is to compare the effect of this resin in industry and laboratory?"

Jan 1, 2018

By F. Bello, J. Engels

"During 2012 and 2013, Minera Esperanza conducted a series of thickening and deposition trials to identify design and operational parameters associated with increased thickening of its tailings. These trials focused on benchmarking the current solids concentration of tailings (62 - 64%) in anticipation of an increase to 67% solids once two new 45 m diameter deep-cone paste thickeners are commissioned in 2014. These trials studied the sedimentation and rheological characteristics of the existing tailings and performed deposition modelling to assist with developing short- and long-term designs for the tailings storage facility. To verify and optimise these models, Minera Esperanza considered a series of laboratory, pilot, and industrial-scale deposition trials. This paper provides a review of the trials conducted in the laboratory and at industrial-scale and considers the results and optimisations for the short- and long-term design of Minera Esperanza’s tailings storage facility."

Jan 1, 2014

By P. K. Fedotov

Centrifugal separation opens its new application fields in the Mining Industry. The up-to-date equipment for ultra-fine ore and concentrates grinding allows an efficient use of centrifugal concentration for micronic gold grains recovery. Moreover, advanced centrifugal concentrators are presented on the market: concentrators with continuous concentrate discharge designed both for ore and non-metallic minerals concentration process. The conducted tests proved the centrifugal concentration to be efficient process for gold recovery from finely ground concentrates and ores (less than 20 µm). Knelson concentrator application for such a fine material in different process circuits makes possible to raise the total gold recovery level of plants. In the circuits of coal plants and in course of coal slimes treatment the centrifugal concentration may be used before flotation in order to improve process performances. A centrifugal concentrator KC-CVD with continuous concentrate discharge working on 0.3 (0.5)mm fraction before flotation is

Jan 1, 2014

By C. S. Gundewar

About 90% of the barytes produced the world over is used for oil and gas drilling as weighting agent in drilling mud to control pressure, prevent blow out and provide lubrication. This is because of its unique properties like high specific gravity, water insolubility and intentness. India is one of the leading producers and exporters of barites. The Mangampeth Baryte deposit in Cuddapah district of Andhra Pradesh, India being the largest single deposit in the world having a reserves of about 80 million tonnes. Approximately 50% of the total reserves of grey barites of Mangampet deposit assays less than 92% BaSO4, the minimum stipulated grade for oil and gas drilling industries. To reach and recover the high grade barite, the overlying low grade has necessarily to be mined out and removed. At present this is being stacked separately at the mine site involving lot of labour and transport cost. Considerable barites is contained in the dumps adversely affecting the conservation and creating lot of environmental hazards. IBM being the premier organization in India in the field of conservation of minerals and environmental protection in mining has recognized the importance of adverse effect of these huge dumps at site. The Ore Dressing Division of IBM, Nagpur has characterized these dumps and developed the flotation process on a sample assaying 66% BaSO4 and 23.3% SiO2. The flotation concentrate obtained assayed 93.7% BaSO4, 2.38% SiO2 with BaSO4 recovery of 80% and meets the requirement of the oil industry. The flotation concentrate being non-wetable, can not be used as such as weighting agent, and hence the collector coating on the concentrate was removed either by acid treatment or heating to make it water wetable. The concentrate was 92% -325 mesh and having a specific gravity 4.3. The barites concentrates so produced meets the size, grade and specific gravity specifications required for use in oil drilling industry. Apart from the financial benefits the process augurs well for the commercial exploitation of these huge dumps in terms of (1) additional recovery of these valuable minerals and conservation, (2) reduction in dumps value, (3) improvement in environment and offering an excellent potential for export.

Jan 1, 2014

By C. B. Wu

This paper presents an analysis of comminution behavior of using cast iron segment (CIS) as fine grinding media with comparison to conventional steel ball. Grinding experiments utilize just one-size medium and mixed size media in laboratory were carried out and its efficiency is expected to be improved. The results show that no matter whether one-size medium or mixed size media employed, grinding efficiency of CIS media can be considerably equal to that of steel ball, on the other hand, grinding product by two kinds of media can conform to Robin-Rammler?s size characteristic curve and distribute in function of . )exp(100nbxy-= Comparing with steel ball, the milling capacity with CIS media could be increased up to about 8.6 percent, overcomminution decreased 3.96 in percentage and qualified size increased 3.98 in percentage in case of grinding fineness retained. At the same time, due to the improvement of grinding product size characteristic and its metal distribution characteristic, the grade and recovery of easy to separation size increased 0.24 in percentage and 6.47 in percentage respectively. Based on these results, the CIS media can be employed as novel fine medium for grinding process substituting for steel ball.

Jan 1, 2014

By Z. S. Abisheva

Results of the study targeted to development of universal acidic-extraction-precipitation technology for gallium recovery from the sublimates are presented in the paper. This will let to utilize a new non-traditional source for gallium production. Phase composition of gallium containing dust was studied. Forms of gallium in the sublimates were determined. The main form is Ga2O3, however, GaP form is also present in the cottrel dust and Na5Ga3F14 form is present in the dust of aluminum electrolysis. The possibility of gallium concentration was established via secondary pyro-selection of the dust. Kinetics of interaction of dust components with sulfuric acid was studied. The products of the interaction subsequently were leached with water. Optimum conditions for direct leaching with HCl and H2SO4 were determined providing gallium recovery from the cottrel dust and the ash carry outs up to 95 %. Gallium recovery from the primary dust and the secondary dust of aluminum electrolysis was at 52; 64 % and 63; 83 % respectively. Effect of Fe, P, K, Na and Al admixtures for gallium extraction from hydrochloric acid solutions was studied. It was shown that gallium chloride complex (GaCl4-) is extracted into the organic phase from the following acid mixtures: HCl + H2SO4, HCl + H3PO4, HCl + H2SO4 + H3PO4, HCl + HF. Kinetic regularities of gallium extraction in the system (tri butyl phosphate) TBP ? HCl - Ga were studied using diffusion cell method with agitation. Optimum conditions for gallium extraction from complex hydrochloric acid solutions with TBP were found providing 99.9 % recovery and separation coefficient for gallium and iron (III) of more than 25 in one stage. Sodium hydroxide and water were selected as reagents for re-extraction of gallium from the organic phase. Different options for disposal of by-products that are formed in the processing of cottrel dust, ash sublimates and dust of aluminum electrolysis were proposed and tested. Keywords: gallium, kinetic, sulfatization, leaching, extraction, technology

Sep 1, 2012

By Priyanka Dhar, Kurt Aasly, Hanumantha Rao Kota, Hassan Bouzahzah, Maria Thornhill

The interest in investigating the processing characteristics of mineral deposits in Norway has seen an upsurge in the last decade. One of the major areas of interest is a huge copper deposit, operated by NUSSIR ASA located in the Repparfjord Tectonic Window in the caledonides of west Finnmark. This study reports analysis of ore from the deposit for development and modifications in the flotation flowsheet for the NUSSIR ASA copper ore. The mineralogical characterization for the ore sample was achived by optical microscopy and Zeiss automated mineralogy while grinding characteristics were tested using Bond Index tests. The results confirmed the presence of Cu minerals in the form of chalcocite, chalcopyrite and bornite in the samples, which are mainly liberated in the – 105 µm size range. The majority of non-liberated copper sulphides associated with silica and the carbonates varies from 3 to 28 percent in the –250 µm samples . It is also observed that the copper minerals are uniformly distributed in all size ranges. Selective flotation of NUSSIR copper ore was performed in different size fractions with a motive to identify the correct liberation size and thus to obtain a copper concentrate meeting the quality requirements. The flotation experiments are essentially performed in two stages: the rougher and the cleaner stage. Mass balance calculations were performed showing that approximately 88 percent of copper can be obtained at the end of the process. Ultimately, overall circuit copper recoveries ranged between 83.5 to 88.1 % with a concentrate grade of 35 to 48 % Cu.

Jan 1, 2018

By Fengnian Shi

In the current energy-sensitive world, sustainable development in the mineral industry will require new, better and more efficient processes. Novel comminution methods, which offer the prospect of achieving the required outcomes of size reduction and mineral liberation at lower energy consumption, are continually being sought. In the past five years, extensive research using high voltage pulse electrical comminution technology has been carried out at the Julius Kruttschnitt Mineral Research Centre (JKMRC), in collaboration with selFrag AG. The major outcome of this research is the development of the concept of pre-weakening ore particles by electrical comminution procedures to reduce the energy consumption in the downstream grinding circuit. The research has also verified the preferential liberation of valuable minerals by electrical comminution. Given the advantages, several potential applications of electrical comminution in the mineral industry are proposed, including AG/SAG mill feed pre-weakening, pebble treatment, ball mill feed pre-weakening, early recovery of the liberated valuable minerals, crack/micro crack generation for improved leaching, and smelter slag treatment. For the mineral industry to utilize electrical comminution, two emerging issues identified from the research need to be address. They are the energy consumption by electrical comminution in the locked cycle treatment and the facilities scale up necessary to move this technology from the laboratory to the plant. Keywords: high voltage pulses, electrical comminution, energy efficiency, mineral liberation

Sep 1, 2012

By Güven Önal, Gülay Bulut, Mustafa Özer, Yunus Emre Benkli, Olgaç Kangal, Mustafa Tarkan

There are various types of natural zeolite deposits in Turkey. Naturally occurring zeolites are excluded from many important commercial applications where uniformity and purity are essential. In this paper, the beneficiation of natural zeolite, taken from western part of Turkey, was investigated. According to X-Ray Diffraction (XRD) and mineralogical studies carried out on the representative ore sample, the natural zeolite was found to be in the forms of clinoptilolite and heulandite. Clinoptilolite forms as a devitrification product of volcanic glass in tuffs. Quartz, clay minerals, orthoclase, plagioclase, biotite, seruzite-muskovite and epidote were observed as impurities. Several types of mineral processing methods were performed in order to remove impurities from the natural zeolite sample to produce high purity zeolite. Gravity separation methods such as shaking table and superpanner were carried out for separating heavy minerals, while high intensity dry magnetic separation was used for discarding magnetic minerals.

Jan 1, 2003

By L. K. Smith

Flotation work conducted by CSIRO on both single minerals and high-arsenic copper ores from a number of sources, has shown it is possible to produce separate low-arsenic copper concentrates and high-arsenic copper concentrates from high-arsenic copper ores. The procedure involves controlled separations at high or low pulp potential regions exploiting subtle differences in the flotation behavior of the arsenic-bearing and non-arsenic-bearing copper minerals. An overview of several case studies investigating the applicability of the controlled potential flotation approach to the separation of copper and arsenic from sulfide copper ores is presented. It highlights the variables which influence the efficiency of the separation which include mineralogy, liberation and reagent selection. The procedure can produce a saleable low-arsenic copper concentrate, which can be directly smelted without penalty, and a high-arsenic low copper concentrate, which will require further processing. Keywords: flotation, copper, arsenic, controlled-potential flotation

Sep 1, 2012

By A. Usov

The studies carried out by the Russian researchers and those carried out jointly within some contracts with scientific organizations and companies of other countries, show that the electric pulse disintegration of materials (ED), proposed and investigated in detail in Russia (Kalyatsky, et al, 1980; Usov et al, 1987; Semkin et al, 1995; Usov and Tsukerman, 2000; Kurets et al, 2002) has been widely recognized and developed abroad (Andres, 1995; Inoue et al, 2000; Biela et al, 2008). The Russian and international journals and the proceedings of the conferences dealing with the electric pulse disintegration pay great attention to the principal principals of selective disintegration of materials. There is no, however, any information concerning both the technical means developed to implement the technique and the assessment of their performance, which would be necessary in objective assessment of the industrial use of the technology. The results of long-term studies of the technique and technologies of electric pulse disaggregation by research institutes such as Research Institute of High Voltages (Tomsk), Kola Science Centre of RAS (Apatity), Institute "Mekhanobr"(S.Pertersburg) described. Exploratory stands and technological installations are developed to carry out pilot tests and operations under production conditions. Basic circuits and classification of technical means electric pulse disintegration of the materials are proposed, the analysis of transportation schemes and classification of the material in the disintegration apparatus are given, construction of chambers for continuous stadial disintegration of ores and materials are presented. The features and technological efficiency of electric pulse disintegration of various types of ores, and the spheres of effective use of the method have been determined. Keywords: electropulse disintegration, disintegration machines, chambers of comminution, stadial comminution.

Sep 1, 2012

By I. S. M. K. Ilankoon

In heap leaching the transport of the acid from the drippers to the surface of the ore particles is a major factor in the overall performance of a heap. This flow behavior is complex as the flow is unsaturated and occurs along a tortuous set of inter-particle channels and connections. Previous modeling of this system has used equations from oil and ground water flow to model these systems, but the applicability of these models with the larger particles found in typical heaps is suspect as these systems are not necessarily capillary dominated. In particular, as the characteristic particle size goes from below to above a few centimeters, the flow changes from capillary to gravity dominated. This means that typical heap leaching heaps cover this interesting, but complex, transitional fluid flow regime. In this paper a set of experimental studies of this flow, including PEPT (positron emission particle tracking) based tracer experiments, highly accurate liquid holdup measurements and axial dispersion experiments using salt tracers will be presented. In this study, flow through mono-dispersed particle beds was carried out. In particular, the hysteresis in the liquid holdup as the liquid flow rate into the particle bed is varied is investigated, since this hysteresis means that the relationship between flow rate and holdup is history dependent, an effect not included in models currently used to describe fluid flow in heaps. A theoretical model that describes this hysteresis will also be presented. Keywords: heap leaching, hydrometallurgy, modeling

Sep 1, 2012

By K. V. Fedotov, G. I. Sarapulova

The study is devoted to the earth's surface protection and is aimed at improving the ecological safety of the territories in the mining industry. Identification of the diagnostic signs and quantitative criteria for the disturbance of soil geochemical properties and water chemistry represent an important scientific task in anthropogenically disturbed landscapes in the context of comprehensive exploitation of mineral resources. The study is aimed at geological and ecological analysis of the migration peculiarities of the man-caused chemicals and elements in soils and soil-surface water environment. We received new results. These results assist in estimating the peculiar features of distribution of heavy metals total and mobile forms (Cu, Ni, Zn, Pb), depending on the physical and chemical parameters of the disturbed soils. We obtained the empirical relationships describing heavy metals localization and accumulation processes depending on buffer properties of soils (pH, N, Corg), salinization factor and contamination with oil products. Anthropogenic geochemical barriers spontaneously formed in the area of industrial facilities were revealed in the territories of industrial facilities. These barriers prevent the further distribution of elements and pollutants in the landscapes. This makes it possible to create their artificial analogues in order to limit further migration of pollutants and to immobilize valuable components. Analysis of diagnostic features of soils geoecological state and factors influencing the distribution of heavy metals in the soil-surface water geosystem allows the identification of the geochemical barrier type with the aim of elements immobilization in a limited area of the territory. We applied modern physical and chemical methods of analysis, a package of statistics programs in Excel and modeling techniques. The proposed approach is innovative and therefore can be attractive. The accumulation of useful components losses in mineral resources exploitation is a promising reserve for their recovery from the soil with specifically arranged properties. The methodology of this research is also promising for the prediction of the environmental emergencies of the anthropogenic nature. This is consistent with the requirements of state control of environmental safety in the course of comprehensive exploitation of mineral resources.

Jan 1, 2018