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By J. J. Lui

Surfactant plays a critical role in many industrial processes such as petroleum, mining, environment and food processing, and daily life. For ionic surfactant systems, adsorption of surfactant at oil-water interface imposes a net charge to the interface. The nature and magnitude of the charges at the oil-water interface depend on charge characteristics of surfactant molecules, concentration of surfactant and solution pH. In our previous study, zeta potential measurement of hexadecane drop-lets in industrial process water was shown to be a simple, yet powerful method for identifying various types of ionic surfactants present in the aqueous system. In this paper, the site-binding model was applied to prediction of zeta potential of oil droplets in aqueous solutions containing a mixture of cationic and anionic surfactant molecules. The total number of interfacial sites for various types of surfactant involved was determined by applying the Gibbs adsorption equation to the measured interfacial tension-surfactant concentration profiles. The distribution of various types of surfactant molecules at the interfaces was evaluated by Langmuir isotherm constants. With the ionization constant of surfactant taken from the literature, the predicted zeta potentials of oil droplets in surfactant solutions from site binding model were shown in a reasonable agreement with the measured zeta potential values.

Jan 1, 2014

By M. Muravyov, T. Kondrat’eva, A. Bulaev

Metallurgical treatments of sulfide ores containing copper and zinc are characterized by significant losses of base metals, particularly formation of the flotation tailings and slags during the dressing and pyrometallurgical treatment respectively. In addition, SO2 gas obtained during roasting and converting may be as raw material for sulfuric acid production. A treatment of the industrial metallurgical wastes has been investigated. Two samples of old pyrite tailings from two concentrators that contained 0.36% and 0.26% of copper and 0.23% and 0.22% of zinc were leached with 10% sulfuric acid in the column. Recovery of copper reached 47% and 38% while recovery of zinc was 47% and 41% from the first and second samples, respectively. The pregnant leach solutions contained 15.9 g/l and 10.5 g/l of ferric iron. Ferric iron is the strong oxidant and ferric containing pregnant leach solutions can be used for ferric leaching of different types of raw materials containing sulfide minerals. Therefore, ferric leaching of copper converter slag flotation tailings contained 0.53% of copper and 2.77% of zinc with the first pregnant leach solution was conducted. The effect of various experimental parameters on the leaching dynamics of copper, zinc, and iron under batch conditions was investigated. Under the best conditions (temperature 70oC, pulp density 30%) the recovery of copper and zinc reached 80% and 42%, respectively. Thus, it has been shown that acid leaching of base metals from old pyrite flotation tailings with using of the pregnant leach solution for the ferric leaching of copper converter slag flotation tailings is a prospective technique for the complex treatment of mining and metallurgical wastes. Investigated processes could be introduced into the technological flow-sheet of typical pyrometallurgical plants.

Jan 1, 2014

By S. A. Kubyshkin, A. A. Agafonov, A. L. Shakhnin, S. M. Sukharzhevsky, A. A. Komlev, N. V. Vorob’ev-Desyatovskii, A. Pichugina

Cyanidation of gold ore results in formation not only of Na[Au(CN)2], but also cyanometallate complexes of some transition metals. During subsequent gold extraction from such solutions and pulps, using activated carbons (??), a number of problems arise. An effective solution of the problem is not possible without detailed knowledge of the interaction mechanism of transition metals cyanide complexes with AC particles. The chemical properties of AC particles and graphene, saturated with [?u(CN)n](n-1)- (n=2, 3), were studied by XPS, ESR, SQUID, and DFT. The obtained results were compared with the data on AC adsorption of anionic form of Ag(I), Au(I), Cd(II), Hg(II), Cr(III), Fe(II), Fe(III), Co(III), Rh(III), Ni(II), Pd(II), Pt(II) and Pt(IV) cyanide complexes. The adsorption of [?u(CN)n](n-1)- (n=2, 3) on AC from aqueous solutions in air is accompanied with oxidation of ?u(I) atoms. Besides, Cu(II) and Cu(III) compounds were found on AC surface. Quantum-chemical calculations confirmed the possibility of formation of Cu(I) complex with carbene-like sites of AC. The reactions of [?u(CN)n](n-1)- (n=2, 3) complexes and aromatic carbenes and their cation-radical were theoretically studied at DFT PBE level to obtain the information on adsorption of cyanometallate complexes on AC. Carbenes with different fragments were regarded as a model of activated carbons, which have free edge sites with paired o and n electrons. It was shown that [Cu(CN)2]- bounds firmly with triplet carbene, if one Cu-CN bond breaks. The dissociation process occurs through a multi-step spin-crossing mechanism to reduce total spin multiplicity of the metal-carbene complex. The behavior of transition element complexes in contact with AC in aqueous solutions is determined by the following characteristics: geometrical structure of ionic complexes; nature of ligands bonded to the central atom; concentration of reactive oxygen species in solution and its pH; nature of binding sites of AC.

Jan 1, 2018

By ?. S. Yusupov, V. P. Isupov, N. Z. Lyakhov, A. G. Vladimirov, S. A. Kondratiev

"Considering the shortage of lithium reserves, the desirability has been shown of studying the possibility of processing into spodumene concentrates the concentration tailings and low-grade ore reserves at Transbaikalian Mining and Processing Project (ZabGOK). The mineral and chemical composition and the particle size distribution of the mineral feed, separability and recoverability of spodumene have been studied, forming the basis for the development of a concentration process and flowsheet for the studied mineral resource. Prospects have been established for impact ore grinding in a disintegrator, the efficiency of mechanochemical processes has been shown in the separation of quartz and feldspar and the recovery of lithium from concentrates.INTRODUCTION Lithium is widely used in various industries - nuclear power engineering, defense technology, power generation, ceramics, special-purpose glass and other technologies. The increasing demand for lithium and its compounds (lithium carbonate and hydroxide) for use in the manufacture of high-tech products (lithium-based materials for chemical sources of electric power and electrochemical energy) explains the need for establishing a sustainable raw material base (Mohr et al. 2012; Moores, 2007). The main sources of lithium are spodumene pegmatites (Vladimirov et al. 2012; Garret, 2004), brines (salars), and hydromineral materials (Garret, 2004; Zeng and Liu, 2009; Kotsupalo and Ryabtsev, 2008). However, in view of the absence in Russia of extractable hydromineral resources of lithium, the practical significance of spodumene ores remains decisive. Russia controls some of the world’s largest reserves of rare-metal pegmatites holding over 8 million tons of Li2O: approximately 7 million tons on the Kola peninsula and 1 million tons in the Sayan mountains. The main lithium mineral in pegmatites is spodumene LiAlSi2O6 containing 8.1% Li2O. It can be efficiently recovered by gravitational concentration and flotation. However, most of the deposits are located in remote areas and none is currently developed. In this connection, special research is focused on technogenic raw materials, which are increasingly seen as a solution to the resource base problem (Chanturia, 2008, Kurkov and Kotova, 2007)."

Jan 1, 2018

By Tracy Shimmield, Philip Samar

"Metals have been mined as ores since pre-history but metal production has increased dramatically in modern times driven by expanding Global GDP. Metal ore mining produces large amounts of waste rock and mine tailings. Mine tailings are the wastes produced after extracting the desired metal from the ore. There are several ways of dealing with this waste, and Ritcey (2005) identifies the following possibilities, land-based storage, backfill to the mine, deep lake disposal and marine disposal. In Papua New Guinea (PNG), both Misima and Lihir Mines adopted the marine disposal option, releasing tailings through a submerged pipe onto the sea floor. This special case is referred to as Deep Sea Tailings Placement (DSTP) in which the tailings deposition is sufficiently deep as to be below the euphotic zone. The most important aspect of deep sea tailings placement is that the tailings are deposited at great depth where exchanges between the seabed and the surface layers are small. The first quantitative multidisciplinary study of tailings impact on the deep sea was carried out from 2006 to 2010 in Papua New Guinea. The physical, chemical and biological work carried out has placed PNG at the forefront of research into the assessment and management of deep-sea environmental impacts related to mining in PNG. The study has provided data which has led to a better understanding of the ecological and geochemical processes in deep water that accompany DSTP in PNG and provided baseline data on deep-sea ecosystems in a scientifically poorly known tropical ocean. Additionally, guidelines on best practice for DSTP have been developed Here we present geochemical data obtained from sediment samples from the marine environment surrounding Lihir and Misima Islands."

Jan 1, 2014

By Stoyan Groudev

Two experimental plots consisting of a slightly acidic soil heavily contaminated with radionuclides (mainly uranium and radium) and non-ferrous metals (mainly copper, zinc, and cadmium) were treated in situ under real field conditions using the activity of some representatives of the indigenous soil microflora. This activity was enhanced by suitable changes in the levels of some essential environmental factors such as pH and water, oxygen and nutrient contents of the soil. The treatment was connected with solubilization and removal of the contaminants from the top soil layer (horizon A) due to the joint action of the soil microorganisms (mainly acidophilic chemolithotrophic bacteria) and leach solutions (diluted sulphuric acid) used to irrigate the soil. In one of the plots, the dissolved contaminants were removed from the soil profile through the drainage soil effluents and were subjected to cleaning by a constructed wetland located near this plot. In the other plot, the dissolved contaminants were transferred to the deeply located soil subhorizon B2 where they were precipitated as the relevant insoluble forms (uranium as uraninite, and the non-ferrous metals as the relevant sulphides) as a result of the activity of the sulphate-reducing bacteria inhabiting this soil subhorizon. This activity was enhanced by injecting water solutions of acetate, lactate, ammonium, and phosphate ions to this soil subhorizon.

Sep 1, 2012

By Kevin Galvin, Simon Iveson

Fine particles are the most valuable because they are the most liberated. However, they are also the most expensive and difficult to recover and concentrate. The Reflux Classifier is a novel invention that combines many of the virtues of existing fine particle separation technologies in a way that provides profound synergies. Multiple parallel narrow channels create a laminar-shear separation zone. The laminar flow provides a well-defined velocity gradient that exposes particles on the wall to a conveying velocity that is approximately proportional to their size, thus reducing the dependence of elutriation velocity on particle size. The high shear rate in these channels generates a hydrodynamic lift force that selectively lifts low-density particles off the channel wall and thus causes them to be preferentially conveyed out in the overflow. Particles that are not elutriated slide back down into the mixing reflux zone beneath the inclined channels which gives them multiple opportunities to re-enter the channels. The resultant suspension of both coarse and fine high-density particles in the fluidized bed zone at the base of the unit generates a strong autogenous dense medium that helps to direct large low-density particles back up to the overflow. The fluidization water also simultaneously de-slimes the high density underflow product. When placed in a centrifuge, the benefits of these features multiply with the improvements in capacity and selectivity that arise from high G-forces. When inverted, these features can be used to perform flotation well beyond the conventional flooding limit. Hence this invention platform has the potential to dramatically improve both gravity and flotation separation performance across the minerals processing industry.

Jan 1, 2014

By G. Demi, G. Belardi, N. Shehu, S. Cico

The physico-chemical interaction between minerals such as olivine, chromite and serpentine and the ions most commonly present in solution, like Ca and Mg and flotation reagents such as EDTA and oleic acid was investigated. The study was conducted via release tests, electrophoretic measurements and microflotation of selected minerals coming from the Kukes deposit (Albania). The results were confirmed by means of beneficiation tests on various types of ores, from the Kukes (Kalimash), from Bulquiza area and from the Rizo deposit (Greece). It has been demonstrated that when Na-K Oleate is used as collector chromite, olivine and serpentine can be separated at pH = 2.5 and/or 5.5 employing EDTA (EthyleneDiamineTetraAcetate) on previously deslimed material. This approach ensures flotation concentrates with a Cr2O3 content about 50%, at a recovery in excess of 65%.

Jan 1, 2003

By J. Menuge, G. Barker

"Liberation (QEM-SCAN) and surface chemical (time of flight secondary ion mass spectrometry -ToF-SIMS) analyses have been undertaken on plant Pb circuit flotation samples with the aim of defining the factors resulting in sub-optimal recovery. Lead flotation circuit feed, cleaner concentrate and tails samples were examined on a size-by-size basis using QEM-SCAN. Sulfide minerals accounted for approximately one third of the flotation feed with pyrite making up 16 wt.%, followed by sphalerite (13 wt.%) and galena (3 wt.%). Non-sulfide gangue minerals comprised calcium carbonates calcite (26 wt.%), dolomite (14 wt.%) with quartz, feldspars and barite all contributing > 5 wt.%. QEM-SCAN analysis indicated that liberation was not the primary cause of the poor flotation response. Principal component analysis was applied to the ToF-SIMS data derived from five samples (as for QEM-SCAN plus rougher concentrate and tails) to enable identification of correlated surface chemical components. Although a significant range of correlations were observed we focus here on those that show a discernible pattern throughout the float circuit. It was found that for the flotation feed the surface of galena were largely obscured but where Pb was observed there was a strong correlation to surface Fe. For the rougher and cleaner concentrates the galena surfaces were relatively clean with no correlation to Fe for the rougher concentrate and minor correlation in the cleaner concentrate. However, in the rougher and cleaner tails the clear correlation of galena with Fe was again apparent. These results suggest, in combination with prior studies of pyrite morphology, that the principal factor effecting grade is the rapid oxidation of the framboidal pyrite resulting in the contamination of the galena surface with a high loading of hydrophilic oxidised Fe species, thus depressing flotation."

Jan 1, 2014

By I. Yochev, A. A. Metelev, A. I. Stepanenko, A. P. Purgin, M. G. Viduetsky, A. M. Panshin, I. F. Garifulin

"Pneumatic flotation cells of the KFM series are intended for the concentration of various ores and technogenic materials. The key operating principle of the flotation cells of the KFM series is the preparation of pulp for flotation in blowers, offering the advantage of an accelerated flotation process. This report summarizes the results of the implementation and operation of the KFM cells at Russian and foreign projects in 2015-2017. Their implementation and operation experience confirms the high efficiency of the KFM cells, especially in the head of lead and zinc, copper and zinc, copper flotation processes:head KFM-600 flotation cell recovers from lead-zinc ore (Rudmetal AD modular concentrator) up to 52% of lead in a single stage (without cleaner flotation) in a salable lead head concentrate (grade of up to 76% lead, 2.3% zinc). The flotation cell proved to be much more efficient than originally expected in the process description in the design phase,flotation of the copper-zinc ore from Novo-Shemur deposit (PJSC Svyatogor concentrator) in two KFM- 1400M cells recovers up to 65% of copper and 70% of zinc in a high-grade bulk copper-zinc concentrate containing 12-13% of copper and 25-28% of zinc. The installation of the two cells with a combined capacity of 26 m3 allowed to decommission 4 chambers of FPM-16 pneumomechanical flotation cells with a combined capacity of 64 m3 with a simultaneous increase in the overall ore concentration performancea single KFM-1400M cell (13 m3) recovers from the copper ore from Volkov deposit (PJSC Svyatogor concentrator) 53% of copper into a high-grade copper head concentrate (33.0% of copper). For comparison, the pneumomechanical cell FPM-16 (capacity 16 m3) has almost half as low copper recovery (29.6%) into the head concentrate at a lower grade (30.5% copper)."

Jan 1, 2018

By Maurício Torem, Gabriela Huaman, Antonio Merma

The purpose of this review paper is to succinctly present the most significant works related to Mineral Processing and Environmental Bioremediation and developed by the Mineral and Environmental Technology Group (METG) of the Materials Engineering Department of the Pontifical Catholic University of Rio de Janeiro (PUC-Rio). In mineral processing it was emphasized the use of the Rhodococcus opacus bacteria as a bioreagent in the bioflotation of some mineral samples (magnesite, calcite, hematite, quartz and apatite). The adsorption of the bacterial cells on the mineral surface can be due to specific and/or non-specific interactions, which will depend on several factors, as their surface charge and hydrophobic character. The zeta potential evaluation of the mineral particles before and after interaction with the R. opacus cells showed that the biomass modified the zeta potential profiles of the minerals, which confirm the adsorption of bacterial cells on the mineral surface. Moreover, the bacterial cells adsorbed caused a change in the mineral flotability which is related to a change in their hydrophobic character, thus, the mineral bioflotability was found to be dependent on the pH and the bacterial concentration. On the other hand, the environmental bioremetiation assessed the biosorption potential of three metal ions (lead, copper, and cobalt) by four different biomass Streptomyces lunalinharesii, Rhodococcus opacus, Rhodococcus ruber and coconut shell powder. For this purpose, biosorption process was characterized under different operating conditions such as initial pH and biosorbent dosage. The Freundlich and Langmuir isotherm models were applied to the equilibrium data obtained at different concentration.

Jan 1, 2014

By N. Nehoroshev, P. Solozhenkin, N. Voyloshnikova, A. Pshennikov

"Molecular modeling of clusters of major bismuth minerals, Bi2S3, was carried out whereby molecular models of minerals and reagents clusters were created. Their HOMO and LUMO energy levels were calculated and using known modelling equations, the absolute hardness ?, eV and electronegativity were calculated. The charges of separate atoms of clusters and the change of properties of the minerals were determined which allowed predictions of the flotation properties of raw ores containing rare bismuth minerals. Modeled complexes containing the clusters of minerals and various collectors were constructed, consisting of atoms and bonds within clusters of minerals. Major physical and chemical parameters were determined for the complexes created, including the total and electronic energy. Based on the energy calculations, predictions of the collector efficiency were proposed. The efficiency of collector was established for various thiolic reagents, the compounds of phosphorus (III) and mixtures of reagents. Theoretical results were checked and confirmed against laboratory ore flotation tests. A gold-bismuth-magnetite ore type was studied where gold, bismuth and iron (magnetite) are of industrial interest. The ore contains 2.8 g/t Au, 1.0 g/t Ag, 0.26% Bi, 45% Fe and 1.25% As. Sulphide mineralization can be mainly found in the form of pyrrhotite, pyrite and arsenopyrite. Bismuth can be mainly found in the form of bismuthite and native bismuth. Gold is fine. A flow sheet for Zhelezny Kryazh ore treatment was proposed. This flow sheet consists of grinding to 95-98% -74 µm, sulfide flotation with two cleaner with xanthate addition, cyanidation of flotation concentrate and flotation tailings included treatment with with CaO (6 kg, 6 hours), cyanidation (8 hours) and CIL (8+24 hours). Saleable products are gold doré, bismuth and iron concentrate."

Jan 1, 2014

By A. J. Lynch, D. K. Tungpalan, Y. Reja, E. C. Avelar, G. Figueroa, S. Gómez, R. Alanis, M. A. Corona-Arroyo

"Have you been on a mine site? This question was posed by Emeritus Professor Alban Lynch to Higher Degree by Research (HDR) Students from the Sustainable Minerals Institute - Julius Kruttschnitt Mineral Research Centre (SMI-JKMRC) in the Student Technical Presentations in 2015. From that question, five HDR students from SMI-JKMRC organised a placement on mine sites in Mexico. The SMI-JKMRC is well known for its tradition to provide their students with opportunities to enhance and test their skills in mineral processing plants. The Student Venture became a short internship for HDR students which had the objective of establishing collaboration with mining companies in Australia and overseas, and of providing a unique experience for the HDR students in regard to their training, professional development, networking and cultural interchange. In return for the companies’ support, the students conducted plant audits to evaluate the process performance thereby providing valuable data to the host company. The 2016 Student Venture was held at the Grupo Peñoles & Grupo Fresnillo in Mexico, in which three mine sites received five HDR students from JKMRC and one young researcher from Universidad de Guanajuato (UG). This paper describes the positive outcomes for the mining company and the students for this experience. The Venture was considered very successful, as it provided valuable training for the students as well as in depth information about the operation of the comminution and flotation circuits of the host sites for the Grupo Peñoles & Grupo Fresnillo. The experience also provided an opportunity for an exchange of knowledge between the HDR students and the site personnel from the host operations. The indication of the success of the experience for all involved was the support of the host company in future student internships."

Jan 1, 2018

By G. Demi

The biggest chromium mineral processing plant in Albania is Bulqiza plant. It has been in operation for more than 20 years, treating low-grade chromium ores grade 20 ? 26 % Cr2O3 and producing chromium concentrates grade 48 ? 50 % Cr2O3. About 2 million tons of tailings with 13 % Cr2O3 content are stocked in a dam close to the plant. Mineral processing of low-grade chromium ores with less than 16% Cr2O3 content is unprofitable because the mining expenses are high comparing with the current market prices of chromium concentrate. Recycle and enrichment of existing tailings is profitable, because there are no underground mining expenses in this case and because that this kind of raw material does not need expenses operation of crushing and grinding. The existing plant is in operation for more than 8 years treating existing tailings as raw material. Grade of concentrate in the value 40 % Cr2O3 and Cr2O3 recovery in the value 30-35% in the plant are considered low. The main reason of low concentrate grade and recovery is high content of particles under 100 microns, the slimes, in raw material. In the paper is described the study carried out to improve enrichment of the tailings, as well as analyses of existing process, raw material and products. It is concluded that majority of lost is present in the slimes which are not separated in existing spiral separators and shaking tables. Basing in the study is composed the new flow sheet of recycling and concentration of the tailings to produce chromium concentrate grade 41 ? 42 % Cr2O3 and recovery 60 %, decreasing in this way the concentrate production cost two times. In the paper are presented the tests and results of concentration of particle size fraction under 100 microns, using gravimetric, magnetic and flotation methods, as well as equipment and machines suitable for slimes treatment and concentration.

Sep 1, 2012

By Qiuyang Hong, Bo Li, Dongyun Liang

"A weathering-crust niobium-rare earth-bearing deposit is formed by the weathering alterationof alkaline granite, which is refractory due to its low grade and complex properties. The mineralogicalcomposition of ore, the grain size of majorminerals as well as the occurrence of Nb and REE are studied in this paper using MLA combined with traditional methods. According to the results, a wide range of Nb-Ti-REE compound minerals including titanoniobite, uranpyrochlore, chlopinite, samarskite and ilmenorutile areformed for the extensive isomorphous substitution among the elements of Nb, Ta, REE, Fe, Ti, U and Th. The occurrence of REE is extremely complex. First, the REEexistingas rare earth minerals including monazite, xenotime, bastnaesite,etcaccount for 21%. Second, the REEexist in the lattice of Nb and Zr minerals as isomorphous additions, which account for 18%. Third, the REE exist as colloidal rare earthdeposit,which account for 35%. Last, the REEexistingas ion-adsorption-type rare earth,which are adsorbedon the kaolinite in the form of hydrated hydroxyl ions, account for 26%.Based on the results of mineralogy, the combined technology process "mineral processing- hydrometallurgical separation" is needed to deal with the ore. The mineral processing tests show that, for the feed ore containing Nb2O5 0.065%, REO 0.13%, an Nb-REE concentrate containing Nb2O5 1.38%, REO 1.98% can be gained by "high intensity magnetic separation-regrinding-gravity separation by shaking tables". The recovery of Nb2O5 and REO is 62.42% and 44.78% respectively. The Nb-REE concentrate is dealt by the metallurgy process "direct reduction- acid leaching & acidulating- neutralization & precipitation- chlorination & distillation" and the rare earth oxide of 92.34% REO as well as the Nb-Zr oxide of 24.62% Nb2O5 can be obtained with the recovery of REO and Nb2O5 being 76.83% and 59.37% respectively."

Jan 1, 2014

By Yessengaziyev Azamat, Almagul Ultarakova, Onayev Murat, Barkytova Botakoz

"The research is aimed at solving the processing of waste products of titanium-magnesium production. The aim of the research is to extract synthetic carnallite and industrial products enriched with niobium from waste products of titanium-magnesium production. Analysis of the current state of the titanium and magnesium production in the Republic of Kazakhstan shows the availability of significant amounts of chloride wastes containing valuable components. Magnesium and potassium with an average content of 50-60 % potassium chlorides, 25-30 % magnesium chlorides are lost in the wastes of the titanium and magnesium production. Ust-Kamenogorsk Titanium Magnesium Plant JSC (UKTMP) currently imports carnallite that is a KCl-MgCl2X6H2O binary salt at quite high prices. Chloride wastes of titanium production, sublimates of dust chambers of a titanium chlorinator, sludge of a magnesium electrolytic unit and sludge of a carnallite chlorinator has been chosen as the targets of our research. The analysis of niobium distribution within any solid waste of a titanium slag chlorination process in UKTMP JSC showed that the highest content of niobium is in the sublimates of dust chambers of a titanium chlorinator in the ranges from 0.26 to 1.0 %. Among the niobium extraction technologies considered, the known method of its extraction from the chloride waste is leaching with weak solutions of mineral acids or alkalis in order to convert the chloride salts into the solution to be used for synthetic carnallite extraction. Besides niobium, other impurity components are transferred to the cake and shall be separated from the base metals. The effective method for this is the chlorination process enabling niobium transfer into the sublimates in the form of chlorides and thus separating it from the majority of the impurities. The condensed niobium chlorides are hydrolyzed transferring it into sediments in the form of oxide. New ways of processing waste products of titanium-magnesium production with the receipt of marketable products are relevant in the development of processing of mineral raw materials."

Jan 1, 2018

By S. I. Anufrieva, N. A. Permyakova, E. G. Likhnikeevich

"Russia’s rare metal reserves are composed of compositionally and structurally complex ores and are characterized by an increased content of natural radionuclides due to their geochemical similarity with rare metals. For instance, concentrates of Zashikhinsky daeposit are characterized by an increased content of uranium (0,06%) and thorium (0,59%); Beloziminsky deposit holds pyrochlore-apatite-magnetite-carbonate ores characterized by increased radioactivity (130 mkR/h) and containing 0,0016-0,0025% of uranium; Etykinsky deposit is characterized by columbite-pyrochlore-microlith mineralization with an average ore grade of 0,013% of uranium and 0,0020% of thorium; eudialyte concentrate of Lovozero deposit (Alluaiv area) belongs to Class II of mineral reserves. Industrial development of these mineral reserves involves the need to comply with environmental standards, public health requirements applicable to finished core and by-products, to take into account the amount and class of the generated radioactive waste, the possibility of disposal or recycling of the radioactive production waste. Concentration processes of radioactive rare metal feeds most often lead to a concentration of natural radionuclides and their accumulation in concentrates. Comprehensive hydrometallurgical processes are currently under development for such concentrates, aimed at producing salable products compliant with the radiation safety standards. The choice of the hydrometallurgical processing method for radioactive rare metal concentrates is based on the mineralogical component of the concentrate, textural and structural features, the distribution of valuable components and impurities, and the content of radionuclides. A systemic approach to the selection of processing methods, in particular integrating several methods, is an effective solution. Methods may not only be combined, but also inextricably linked with each other. Hydrometallurgical processing methods include leaching by acidic and alkaline agents; sulfatization for selectively decomposing the minerals and moving the bulk of U and Th into solution; fluorine extraction process. Methods of precipitation and co-precipitation, extraction (by liquid and solid extractants), sorption, and ion exchange are used to decontaminate the solutions by removing thorium, mezathorium, uranium, and their radioactive decay products. Agents used in hydrometallurgical processing of radioactive rare metal ores include sulfuric, nitric, hydrochloric, hydrofluoric acid, alkali (NaOH, KOH), sorbents (for example, AB-17) for sorption of uranium and extractants (mono- and bidentate organophosphorus compounds, diamides, etc.) for the extraction separation of rare, rare-earth, and radioactive elements."

Jan 1, 2018

By Zhiyong Gao, Ruiying Fan

"Crushing and grinding are the prerequisite processes in many industries, such as minerals processing and powder technology. During crushing and grinding, minerals will cleave or fracture along the directions by broken the interlayer bonds (e.g., ionic bonds), generating some commonly exposed surfaces. The broken (or dangling) bonds at the generated surface makes the surface more active and determine the reactivity of the surface. In this work, the population of broken (or dangling) bonds on commonly exposed surfaces of fluorite mineral (a chosen model mineral) was calculated. Based on the calculated broken bonds information, the anisotropic surface reactivity of fluorite such as surface energy, surface relaxation, dissolution, wettability, surface charge and adsorbability, were discussed. The results show that the surface broken bonds density, which is positively related to the surface energy, can be used to predict the cleavage nature, surface relaxation degree and surface stability of fluorite crystal. The distribution characteristic and the number of broken (or unsaturated) bonds of surface active atoms (like Ca for fluorite crystal) can be used to predict and explain the anisotropic wettability, surface charge and adsorption mode and strength of organic molecules on different commonly exposed surfaces. It is easy to conclude that the calculation of surface broken bonds can serve as a fast and accurate way to start the mineral chemistry studies. These findings will be helpful to the mineral/material chemistry research in related interfacial science communities.INTRODUCTIONGrinding for mineral liberation is a prerequisite for a successful flotation separation. Also grinding for size reduction is a prior process for a favorable powder technology. During the grinding process, the minerals / materials will cleave and fracture along certain crystal directions with relatively weak interlayer chemical bonds1 to form a number of common exposed surfaces. Exposed surfaces are the outer boundary of a solid substance. In the mineral / material block, the bonding orbital of the atoms is filled with electrons and the atoms are in a steady state. Atoms on these exposed surfaces appear to show dangling bonds (or broken bonds) by losing chemical bonds to adjacent atoms in the previous block. Therefore, surface broken bonds serves as an initial property of a fresh surface. The lattice arrangement and crystal orientations causes differences in the number of dangling bonds on each exposed surface, i.e., anisotropic surface broken bonds2. The anisotropic dangling bonds enable the exposed surfaces to show varying degrees of surface reactivity (including surface energy, surface charge, surface relaxation, dissolution, wettability and adsorption behavior), known as anisotropic surface reactivity."

Jan 1, 2018

By T. Wajima

"A novel carbonaceous immobilizing agent for heavy metal contaminated soil was prepared from rice straw using sulfur immersion and pyrolysis, and the lead immobilization in artificial contaminated soils using sulfur-impregnated carbonaceous material was estimated. The rice straws were cut to 1 cm pieces, and then immersed in 0.1 - 1 M K2S solution for 0 - 24 h to prepare sulfur-immersed materials. The immersed-materials were heated at 400 oC for 1 h in nitrogen gas to produce the sulfur-impregnated carbonaceous material by pyrolysis. The abilities of the product to immobilize lead from aqueous solution were examined to obtain the product with high lead immobilization ability. With increasing K2S concentration, the immobilization ability of the product for lead gradually increases and then above 0.5 M K2S those are almost constant, while 15 min is sufficient for the immersed time to obtain the product with high lead immobilization ability. The product prepared from material immersed in more than 0.5 M K2S solution for less than 15 min has a maximum immobilization ability for lead ion. The lead immobilization using the sulfur-impregnated product is sustainable due to the formation of leadhillite [Pb4SO4(CO3)2(OH)2] and anglesite [PbSO4]. The product can immobilize lead ion in various artificial lead contaminated soils. By mixing artificial lead contaminated soil with the sulfur-impregnated product, the eluted solution became neutral, and the eluted concentrations of lead ion dropped below the Japanese elution standard for soil.INTRODUCTION Soil contamination with heavy metals is a worldwide problem. Accumulation of heavy metals in soils affect soil ecology, agricultural productivity, quality of agricultural products, water resources, and serious health problems for human and animal (Raicevic, et al., 2005). In the United States, for example, approximately 63 % of the sites on the National Priority List (NPL) for the treatment of contaminated soils are contaminated by metals, and lead is the most common metal, found at 15 % of the sites. In Japan, according to a report by the Ministry of Environment, 43 % of the contaminated sites that exceed the environmental quality standards are contaminated by lead compounds. Soil contamination by lead compounds is also prevalent in other developed and developing countries where lead compounds are used extensively in industrial activities without careful contamination management. Lead is a ubiquitous heavy metal pollutant in soils due to their use widely. The primary sources of Pb contamination include industrial activities such as mining, smelting of metals, and the use of Pb-containing products such as paints, lead-acid batteries, bullets, gasoline and pesticides (Cao, et al., 2009). It can damage human nervous (especially children) and reproductive systems (ATSDR, 2007). The high concentration of Pb in the soil poses risks to human and animal health by the leaching of metals from the soil into water and the consumption of edible plants growth in the contaminated soil. Therefore, proper remediation is necessary to reduce metal availability in soil for protecting human health."

Jan 1, 2018

The present study investigates the nature of gold mineralogical distribution and association in a Cu-Au flotation circuit (1.6 g/t Au, feed head grade). The approach used in this study involves a combination of bulk gold assay and quantitative X-ray diffraction (QXRD), on a size-by-size basis, followed by QEMSCAN analysis on the -75+53 µm, -53+38 µm and -38+20 µm size fractions. The QXRD and QEMSCAN analysis showed that gold mineralogy is complex and fine-grained in the flotation feed, particularly in the -38+20 µm size fraction. Gold and pyrite concentration follow each other closely, suggesting gold-pyrite association. Quartz as the major gangue mineral shows a bi-modal distribution with respect to particle size. The identified gold particles were completely locked (~94 %) in pyrite as fine inclusions and 6 % locked as complex aggregates (-75+53 µm size fraction) whereas in the -38+20 µm size fraction, the identified gold grains occur as fine inclusions (~1-3 µm) within pyrite and silicates. However, in the intermediate size fraction (-53+38 µm), 75 % of the identified gold grains (10-22 µm) were over 90 % liberated and 25 % associated and locked in pyrite and complex aggregates (~2-4 µm). The identified gold grains in the -53+38 µm size fraction occurred as native and electrum with varying silver concentration between 8 and 20 % by weight. In the -38+20 µm size fraction, a gold telluride was also identified. Based on the mineralogical analysis of the feed, possible flotation strategies are discussed. Optimizing the flotation of pyrite is suggested as the primary Au recovery strategy. Keywords: flotation, pyrite, gold, liberation, QXRD, QEMSCAN

Sep 1, 2012