Ore Flotation Research Articles

Study of rinsing wastewater purefication from zinc ions by magnetic sorbents

The prospects of increasing of environmental safety level for industrial enterprises as a result of the use of the modern ferromagnetic sorbents for the purification of rinsing wastewater from heavy metal compounds are considered. The structure of the obtained powder sorbents was studied by the granulometric method and X-ray phase analysis. A laboratory setup was developed to study of influence of sorption parameters on extraction degree of toxic substances from wastewater. The sorption properties of powders obtained by co-precipitation of polyvalent ferrum compounds, electroerosion dispersion of steel shavings and iron ore flotation concentrate are compared. Effect of ultrasonic treatment of coprecipitation reaction mixture and the speed of mixing of the sorption mixture on the quality of wastewater treatment from zinc ions was studied. The best results of sorption water purification were achieved with use of freshly obtained pasty suspension of ferritization coprecipitation at a stirring speed of the sorption mixture of 1200 rpm. It was found, that under such conditions a high degree of extraction of Zn2+ ions ̶ 98 % is ensured, and the resulting purified solution meets the standards for the content of zinc ions in water for its reuse in the rinsing operations at electroplating facilities. The use of research results at industrial enterprises will prevent environmental pollution by toxic heavy metals, replace inefficient technologies, and ensure rational use of water and raw materials in the industrial productions.

Improve Bastnaesite Flotation via Synergistic Effect of Octyl Hydroxamic Acid and Octyl Phenol Ethoxylated Surfactants

ABSTRACT The large loss of fine-grained bastnaesite has become an increasingly important issue restricting the development of rare earth ore flotation industry. To solve this issue, a new collector mixture that combines octyl hydroxamic acid (OHA) and octyl phenol ethoxylation (OP10, the number of ethylene oxide groups is 10) is proposed to be used to improve the flotation of bastnaesite. The flotation adsorption mechanism of OHA/OP10 on bastnaesite was investigated by a series of experimental and analytical tests. The results showed that when the molar ratio of OHA/OP10 was 3:1, the OHA/OP10 combination significantly improved the recovery of −74 + 38 μm and −15 μm bastnaesite compared with only OHA. Optical microscopy revealed that mixed OHA/OP10 had a beneficial effect on fine-grained bastnaesite aggregation. In addition, the results of the zeta potential test, fluorescence spectrum analysis, and XPS analysis showed that OHA and OP10 were co-adsorbed on the surface of bastnaesite.

Technology for increasing the precious metals content in copper concentrate obtained by flotation

In the established technologies, the use of classic depressants of pyrite, such as lime represents one of the main problems in the flotation of gold-bearing copper (Cu) ores. Lime addition leads to the depression of the noble metals - gold (Au) and silver (Ag) that end up in tailings. Thus, the operator incurs economic losses. The current paper presents research aimed at replacing in flotation of copper pyrite ore, bearing gold and silver, the classical depressor lime with catholyte, i. e. with solution obtained during the electrolysis of water (pure or aqueous solutions) using a diaphragm electrolyser. Data from the conducted research show an increase in the content of precious metals in the obtained copper concentrate - from 148. 04 g/Mg Au and 112. 8 g/Mg Ag achieved by classical process to 216.45 g/Mg Au and 174.03 g/Mg Ag obtained by the proposed treatment. At the same time the Cu recovery increased by 3 % and the grade of Cu concentrate was 27.5 % Cu (compared to 16.2 % in the classical process). It seems that the main parameter influencing the selection separation process is the catholyte pH value.

On the impact of grinding conditions in the flotation of semi-soluble salt-type mineral-containing ores driven by surface or particle geometry effects?

Grinding and flotation processes are often studied independently, despite the well-established grinding influence on flotation performance, which affects not only particle size and thus liberation but also shape and leads to complex changes in pulp chemistry affecting the particle surface properties relevant for selective bubble attachment. Yet, no study jointly investigated these possible causes and many are limited to single mineral flotation. We relate grinding conditions to changes in pulp chemistry and particle surface properties and assess their impact on upgrading. We studied three non-sulfide ores with different feed grades and valuables: scheelite, apatite, and fluorite. These were dry-, wet-, and wet conditioned-ground before flotation in a laboratory mechanical cell. Results were evaluated with bulk- and particle-specific methodologies. The selectivity of the process is higher after dry grinding for the fluorite and apatite ores and irrelevant for the scheelite ore. Variations in flotation kinetics of individual particles associated to their size and shape are not sufficient to explain these results. The higher concentration of Ca2+ and Mg2+ observed in the pulp after wet grinding, altering particle surface properties, better explains the phenomenon. Additionally, we demonstrate how particle shape impacts are system specific and related to both entrainment and true flotation.

Graphite ore flotation efficiency using bio ester collector formed by transesterification

Bench scale flotations were carried out to investigate an alternative collector reagent with a more sustainable bias, with selective action at the mineral interface to replace the standard hydrocarbon-base collector used for graphite’s flotation, the kerosene. A soy bio oil was produced by a transesterification reaction to perform as a collector. The study used graphite ore with 5.85% carbon content obtained from Salto da Divisa/MG region, in Bahia-Minas Province, Brazil. The design of experiments showed that the bio ester performed 11% higher than kerosene as a graphite’s collector, improving the flotation’s selectivity with 62% ore grade by bio oil and 88% recovery, against 54% ore grade using kerosene and 77% recovery. The chemical composition investigated with XPS analysis for both concentrates with kerosene and bio ester demonstrated the influence of esters and oxigenated-groups on oxidized graphite surfaces.

Comprehensive Utilization of Pyrite Concentrate Pyrolysis Slag by Oxygen Pressure Leaching

The preparation of high-purity sulfur and pyrrhotite by pyrolysis holds great potential to realize the high-value utilization of pyrite concentrate (FeS2), i.e., a by-product during the flotation of sulfide ore. In this study, the pyrrhotite obtained from the pyrolysis of pyrite concentrate was taken as the study object, and the effects of acid types, initial acidity, leaching time, leaching temperature, oxygen pressure, and liquid-to-solid ratio on the leaching behavior of pyrrhotite under oxygen pressure, were explored. The results show that elemental sulfur and hematite-based iron residue can be obtained by oxygen pressure leaching of pyrrhotite. It is found that the optimal experimental conditions for pyrrhotite oxygen pressure leaching are hydrochloric acid with 0.8 mol/L of initial acidity, 5 h of leaching time, 0.8 MPa of oxygen partial pressure, and 9:1 of liquid to solid ratio at 150 °C; moreover, the yield of sulfur reached 88.37%. Under optimal conditions, the leaching ratios of Fe, Pb, and Zn were 19.8%, 92.25%, and 99.11%, respectively. The sieved leaching residue was roasted at a low temperature of 500 °C, where the grade of Fe in the obtained hematite iron powder was 61.46%, and the grades of Pb, Zn, and S were 0.082%, 0.024%, and 0.1%. Clearly, the results meet well with the standard of the first grade of pyrite cinder, and this process realizes the comprehensive recovery of Fe and S resources in pyrolysis slag, which provides a superb technical route for the high-value utilization of pyrite concentrate.

Application of inverse gas chromatography to bench scale flotation of sulphide ore

ABSTRACT Inverse gas chromatography (IGC) is receiving increasing attention due to its high precision and ease of application in determining various characteristics of a wide variety of materials of different shapes and morphologies. This study details an experimental investigation into the application of the IGC technique to the flotation of sulphide minerals. Rather than giving the surface energy, the trends associated with the various concentrates and tailings are described. Bench-scale flotation experiments of a nickel-copper sulphide ore were conducted in a Denver flotation cell. The IGC analyses were carried out on the timed concentrates, as well as on the final tailings, in order to evaluate the correlation between surface energetics and the flotation response of the ore particles. The results indicated that the floatability of the concentrates was directly related to the surface energy of the particles. Both dispersive and specific components of surface free energy increased by increasing the necessary time for the particles to be floated, which was consistent with the obtained values for the work of adhesion to water. However, the flotation response of the tailings was not consistent with the expectations from the surface energy value. The significance of the sample composition, particle size distribution, and their consequences in surface energy-flotation response relationship were also observed.

Interfacial Adsorption Mechanism of Diethyldithiocarbamate in High-Sulfur Residue Flotation

Diethyldithiocarbamate (DDTC) is employed in the sulfide ore flotation process due to its excellent collection performance. Herein, we investigated the interfacial adsorption behavior of DDTC on the four main mineral phases of high-sulfur residue: sulfur, pyrite, sphalerite, and lead sulfate. The adsorption behavior of DDTC and H2O, namely, the adsorption structure and the energy and electron localization function cross section, were explored using density function theory calculation. The results were helpful in constructing a coadsorption model of DDTC and H2O, which was validated by pure mineral flotation and characterization of Fourier transform infrared spectra. The coadsorption model indicated that the adsorption of DDTC on sulfur, sphalerite, and lead sulfate was weak with physical bonding, while its adsorption on pyrite was strong with chemical bonding. Practical bench-scale high-sulfur residue flotation was performed, and the result was different from that obtained from pure mineral flotation. Our developed model predictions and mineral fugacity pattern analysis were synergistically used to explain this difference. Overall, this work proposes for the first time a coadsorption model of DDTC and H2O and provides important insights into interfacial adsorption in high-sulfur residue flotation.

Justification for Criteria for Evaluating Activation and Destruction Processes of Complex Ores

The mining industry is faced with the problem of depletion of reserves of easily beneficiated minerals containing valuable metals. The characteristic features of the ores involved in processing are fine dissemination; low content of valuable components; and similar physical, chemical, surface, and technological properties of minerals, among others. Under such conditions, increasing the efficiency of mineral processing becomes of primary importance. Creating highly efficient, environmentally safe technologies on the basis of deep study of the material, chemical, and mineralogical composition, as well as using and developing methods and techniques for testing mineral materials at successive stages of raw material transformation, enable to solve such problems. Criteria for assessing the flow of technological processes are presented in the article. A complex criterion is substantiated and proposed for quantitative assessment of the degree of physical and energy impact at the stages of ore preparation and flotation enrichment of mineral raw materials. The criterion is calculated on the basis of activation energy data calculated by differential and integral kinetic methods. In addition, an empirical indicator was introduced into the complex criterion, which allows increasing the accuracy of the calculated criterion. This criterion not only allows to estimate the degree of influence from the position of averaged estimation on the full interval of degrees of transformation from 0 to 1, but also gives the possibility to consider the required number of degrees of transformation; for example, if it is necessary to make estimations on narrow temperature intervals. The calculation of empirical parameters for the obtained criterion is carried out before and after the application of physical–energetic methods of influence using thermal analysis.

An investigation into the use of xanthate, trithiocarbonate and thiourea collectors on the flotation of sperrylite (PtAs2)

Sperrylite contributes about 21% to the total platinum group minerals (PGMs) found in the Platreef ore deposit. The recovery of sperrylite by flotation has been shown to be poor and the reasons for this are not well understood. Xanthate collectors have been widely used in flotation of PGM ores, especially in the recovery of PGMs associated with base metal sulfides. However, previous studies have shown that these collectors are not as successful in recovering sperrylite. This study has compared the use of xanthates with collectors with different functional groups, increased dosages, as well as high ionic strength of process water on the floatability of sperrylite. The xanthate, trithiocarbonate and thiourea collectors investigated were shown to adsorb on sperrylite to varying degrees, but at a dosage equivalent to about one pseudo-monolayer coverage they did not impart sufficient hydrophobicity to the mineral to induce significant flotation recovery, with the recoveries ranging between 15 and 18%. Increasing the dosage of a strong collector such as PAX or the ionic strength of the process water used in the flotation was shown to improve the recovery of sperrylite to 45% at 20 monolayers of PAX and 20.6% at 0.12 M ionic strength. Batch flotation tests showed that the increases in sperrylite recovery achieved under different conditions were non-selective towards sperrylite and came at the expense of an increase in total solids recovered. This investigation has provided further insights into the possible reasons for the poor floatability of sperrylite which may guide future work on improving the recovery of this economically important mineral.

INFLUENCES OF GRINDING CONDITIONS ON GALENITE-SPHALERITE FLOTATION KINETICS

Grinding is more than just crushing, it is also a process that causes a chemical reaction on the surface of the mineral. Water used in the grinding process significantly affects the galvanic interaction. 
 Different grinding conditions result in different pulp chemistries. This becomes especially important in sulfide flotation in terms of recovery and selectivity. There are limited studies examining the effects of dry and wet grinding prior to the flotation of sulfide minerals. This study compared the effects of wet and dry grinding on the flotation kinetics of complex Pb-Zn sulfide ore at P80 of 20 and 50 µm grind sizes. Results showed that dry grinding positively affected the sphalerite ore flotation compared to wet grinding in terms of recovery and grade in both galenite and sphalerite rougher flotation stages. Considering that the effect of dry grinding was due to the difference in pulp chemistry, the reasons were explored based on particle morphology, and pulp potentials. 
 The results showed that grinding the same ore under dry and wet conditions significantly affected the flotation performance. In light of the pulp potential measurements, it was determined that the reducing environment obtained in the wet grinding negatively affected the flotation performance, while the oxidizing environment formed during the dry grinding affected the flotation performance positively. This was attributed to the fact that galvanic interactions that occurred during wet grinding were significantly reduced during dry grinding. Hence, better galenite and sphalerite flotation was obtained following dry grinding.

The use of pracaxi oil collector in the selective flotation of xenotime from silicates

Rare earth elements have played a key role in technological advancement, attracting great visibility in the global commodity market. Xenotime, a heavy rare earth resource (YPO4), can be found associated with granitic rocks, as in the Pitinga deposit, located in the Brazilian Amazon region, where the main gangue minerals are quartz, microcline and albite. This research investigates the application of a new collector produced from pracaxi oil, an Amazon oil abundant in Brazil, in the selective flotation between xenotime and its main gangue minerals. The study conducted the synthesis and characterization of the collector, the chemical, mineralogical and surface characterization of minerals, as well as the evaluation of collector adsorption and flotability via microflotation tests, zeta potential measurements, surface tension determination and XRD, WDXRF, ICP-MS, FTIR and XPS analyses. The pracaxi collector was found to be mainly composed of oleic acid (56.2%), linoleic acid (14.1%) and behenic acid (10.6%), in addition to exhibiting a critical micelle concentration (CMC) of approximately 150 mg/L. Microflotation tests indicated that the best condition for selective recovery of xenotime occur at alkaline condition (pH 9.0), presenting selectivity of approximately 90% with collector concentration of 10.0 mg/L. The zeta potential data confirmed a selective adsorption of pracaxi collector onto xenotime, with an increase in the surface charge from −30 mV to −68 mV, whereas no significant changes were detected in the silicates. The FTIR spectra showed the appearance of a band at 1545 cm−1 on the surface of the xenotime after collector adsorption, which indicates, along with the zeta potential data, the chemical nature of the adsorption. The presence of small amounts of iron in the lattice structure of silicate gangues can act as an activator, and therefore, may be responsible for the small flotability of these minerals. The performance of the pracaxi oil collector presented in this study indicates the great potential of this Amazonian oil for application in the selective flotation of xenotime ores found in the region.

Improved Flotation of Fine Flake Graphite Using a Modified Thickening Process

Natural graphite ores are usually upgraded by froth flotation. However, complex processes with multistage grinding and flotation are required to achieve decent liberation and separation of graphite and gangue minerals. This study reports a short and improved flotation process for fine flake graphite ore by employing a thickening stage. The results indicated that increasing the regrinding concentration via thickening can improve the grinding efficiency and, thus, shorten the separation process. With thickening, a high-grade intermediate concentrate of 96.01% was obtained after three steps of cleaner flotation, which is close to the final concentrate after five steps. Particle size distribution analysis and FIB-SEM-EDS studies suggested that the main contribution of thickening–regrinding was to achieve better abrasion rather than attrition of the graphite flakes, thus liberating the interlayer impurities without reducing the size of the graphite flakes. This study offers a more cost-effective pathway for the simplified flotation of natural graphite ores.

Contribution of ammonia in xanthates adsorption onto copper oxide mineral surface in high-alkaline solution

Ammonia is a useful modifier for enhancing surface sulfurization in copper oxide ore flotation using xanthate as a collector. However, its potential role in the reaction of sulfhydryl collector with sulfurized copper oxide mineral in a complex pulp has been neglected. This work investigates the contribution of ammonia to xanthate adsorption on the sulfurized malachite surface, independent of its effect on sulfurization. Zeta potential measurements indicate that NH3·H2O increases the surface potential of malachite and enhances the proximity of xanthate to the malachite surface in a strong-alkaline solution. Adsorption tests and time-of-flight secondary ion mass spectrometry analysis demonstrate that NH3·H2O can increase the xanthate adsorption density. Spectroscopic analysis reveals copper(I) xanthate and dixanthogen as the primary xanthate products, with their quantities increasing upon NH3·H2O treatment. Thermodynamic analysis of the reaction of malachite, HS−, and xanthate to form copper(I) xanthate and dixanthogen shows that NH3·H2O treatment enhances the stability of the reaction compared to its absence. Thus, NH3·H2O treatment increased the recovery of sulfurized malachite by over 10%. This study offers a comprehensive understanding of ammonia modification for enhancing sulfurization–xanthate flotation of copper oxide minerals and provides a scientific basis for developing high-efficiency collectors.

A case study of flotation of chalcopyrite-molybdenite ore using a mixture of pyrogallic acid and o-isopropyl ethylthiocarbamate: Insights from ab initio calculations

To date, lime-free flotation processes are increasingly advocated due to many problems caused by the traditional process using lime (CaO) as a depressant and xanthate (BX) as a collector. In this work, we developed a combination of pyrogallic acid (PGA) and o-isopropyl ethylthiocarbamate (Z200) as an eco-friendly alternative to the lime-xanthate process for chalcopyrite-molybdenite (ccp-mlb) flotation. Roughing flotation experiments showed that this process yields ccp-mlb concentrate with similar recovery and grade of Cu and Mo as in the traditional lime-xanthate process. However, the huge advantage of the novel process is that it requires ten times lower dosages of sodium sulfide in the subsequent separation of ccp-mlb concentrate. The ab initio calculations explained this trend at the atomistic level, where hydrogen sulfide ions could desorb collector more easily from the Z200@ccp complex compared with BX@ccp. The same method could be applied for environmentally friendly separations of other resources with similar composition.

Effect of the hydration film on the surface sulfidization of different oxide ores: A DFT study

Sulfidization is a commonly used pretreatment process to improve the flotation of oxide ores. However, not all oxide minerals can be sulfidized. The huge sulfidization differences between smithsonite and quartz are a typical example. In this paper, DFT calculations were used to simulate the sulfidization of different oxide ores with smithsonite and quartz as an example. The calculation results showed that the hydration film plays a decisive role in whether the oxide ore can be sulfidized or not. For the smithsonite, HS can break the barrier of its surface hydration film and it can be sulfidized. However, for the quartz, due to the powerful obstacle of its surface hydration film to HS, its sulfidization failed. To find out the internal mechanism, the overlap population, PDOS, and electronic configurations were further analyzed, and their relationship with sulfidization behaviors was established. The analysis results demonstrated that Zn-O bond was more vulnerable than Zn-S bond while Si-O was much more intense than Si-S bond. Moreover, a mechanism model was also proposed to elucidate the different impacts of hydration film on the sulfidization of these two representative minerals. This work is helpful to enhance the understanding of different oxide ore sulfidization.

Combined microflotation effects in polymetallic ores beneficiation

Producing of heterogeneous concentrates with good recovery in the processing of polymetallic ores is a challenge. Many factors must be taken into account including ore grinding, reagent mode, water composition, pulp density and the volume of supplied bubbles when producing high-quality selective concentrates. Microbubbles smaller than 50 μm in size were produced based on the frother oxal T-92 at different concentrations using a generator. The most optimal number of microbubbles smaller than 50 µm was produced at a T-92 concentration of 0.5 g/dm3. Polymetallic ore of Kazakhstan deposit was used for flotation studies. The studies were conducted in the copper-lead rough concentrate producing cycle. Flotation active minerals chalcopyrite and galena pass into the foam product, while sphalerite and pyrite remain in the chamber product in this cycle. In this paper, the density of pulp (20, 30 and 50%) as one of the main factors that effects the selectivity of flotation is studied. The kinetics of ore flotation in the base mode and with the use of a microbubble generator has been studied at these densities. Test experiments have been performed at the optimum density. The use of a water–air microemulsion generator makes it possible to maintain the quality of the copper-lead concentrate and increase the extraction of copper into the rough concentrate by 7.41%, lead by 5.98%.

The utilization of tamarind seed gum as a novel dolomite depressant in the selective flotation of apatite from dolomite

In this study, the separation of apatite from dolomite was first investigated by using tamarind seed gum (TSG) to depress the flotation of dolomite in sodium oleate (NaOL) collector system. The effects of pH and flotation reagents concentration were studied, and the results indicated that TSG could strongly depress the dolomite floatability rather than apatite floatability. A satisfactory separation effect was realized when pH was 9.0, TSG dosage was 10 mg/L and NaOL dosage was 40 mg/L, at which the recovery of single apatite and dolomite was 80.28 % and 3.46 % respectively, and the grade of P2O5 and the recovery of P2O5 of the concentrate was 35.86 % and 76 % respectively in mixed ore flotation experiments. To reveal the adsorption mechanism, the flotation reagents adsorption morphology, adsorption type, and adsorption site were analyzed through AFM images, zeta potential measurements, FT-IR spectra, and XPS spectra, respectively. It was found that TSG was adsorbed on apatite by hydrogen bond while adsorbed on dolomite by chemical bond. Hydrogen bond was weaker than chemical bond, thus NaOL could still express the strong adsorption on apatite surface when TSG was used as depressant, while TSG could impede NaOL to be adsorbed on dolomite. Therefore, TSG selectively restrained the flotation of dolomite, achieving the separation. Furthermore, the XPS results uncovered that the Ca and Mg of dolomite were the main active sites that react with TSG.

Post-Leaching of Silver from a Non-Sulfide Lead–Zinc Ore Flotation Tailing Leach Residue in a Copper–Ammonium Thiosulfate Solution: A Fuzzy Logic Prediction

Post-Leaching of Silver from a Non-Sulfide Lead–Zinc Ore Flotation Tailing Leach Residue in a Copper–Ammonium Thiosulfate Solution: A Fuzzy Logic Prediction

Разработка метода и прибора для измерения сил в контактах частиц в условиях флотации микродисперсий золота

Introduction. In flotation of gold-containing ores, metal losses with tailings are mainly related to the fine particle size classes - micro dispersions. Study of the physical nature of the forces in the contacts between the particles, including gold micro dispersions, allows gaining new knowledge associated with the solution of the pressing problem of effective extraction of difficult to extract forms of the precious metal by flotation. Materials and methods. Measurement of the forces in contacts of particles was carried out by sediment volumetric method using the developed device. The method allows to determine the forces in contacts of particles by the volume of their sediment, formed as a result of kinetic destruction of the disperse system. Alluvial gold from the collection formed during the experimental tests of the equipment of separation complexes "Shlich", "Shlich-2", "PGShOK-50-2" was used in the experiments. The results of measuring the forces were supplemented by theoretical studies, which had the aim to estimate the contribution of the fluid volume held by capillary forces in contacts of particles to the volume of sediment. Results. It was found that the volume formed by the kinetic destruction of the disperse system is determined by the force in the contacts of particles, and the volume of capillary held liquid is of subordinate importance. Discussion. It is shown that the results obtained can be explained by involving the notions of boundary layers of fluids with a structure changed under the influence of surface forces. The low-entropic structure of liquid in the boundary layer of hydrophobic surface is caused by forces arising inside liquid itself near weakly interacting surface, and is energetically the least favorable, corresponding to the maximum of free energy. Therefore, the particles behave as if there are hydrophobic attraction forces among them. Conclusion. Uncompensated charges near hydrophilic surface create high-entropic structure of water with normal orientation of its dipoles and increased density, which causes the appearance of structural hydrophilic repulsive forces among particles. Resume. Structural hydrophobic attraction and hydrophilic repulsion are endothermic processes. Their violation will be an exothermic process and its exo-thermicity increases as the temperature rises. The developed method of flotation is based on this property of structural forces: the stability of wetting films in flotation processes of micro-dispersions of minerals is changed by heating water in the boundary layers of air bubbles - hydrophobic cavities in water - due to the condensation heat of hot water vapor. For this purpose, aeration of the flotation system is carried out by a mixture of air and steam. Proposals for practical application and direction of future research. Practical significance of the project is to develop technology for flotation of the most difficult to extract forms of gold. Its essence is based on the effect of preferential adhesion of gold micro-dispersions on its own hydrophobic large particles - a solid wall. Thin plates, flakes and sheets of native gold are used as it. The aggregates formed by the above described mechanisms from poly disperse particles are extracted by flotation. In case of extraction in several steps the rough concentrate can be used as a solid wall (carrier minerals). In further research it is necessary to develop an organizational mechanism of joint processing of ores and gold placers.