Search Documents

By A. A. Rogozhin, E. G. Likhnikevich, S. I. Anufrieva, A. V. Kurkov

"Russia is among the nations holding the world's largest lithium ore reserves. Lithium is of key importance for the global economy. Therefore, it is important to review the current state of technology research aimed at finding the most effective solutions for the recovery of lithium from promising reserves in Russia. In Russia, a number of process solutions for the flotation of spodumene into salable concentrate (5% Li2O) have been implemented at the earlier existing complex low-grade ore concentration project. By applying these solutions, a sample of high-grade spodumene ore (4.7% Li2O) of the Greenbushes deposit was processed into a spodumene concentrate (7.5% Li2O) at a high recovery (~93%) of lithium. In Australia and Canada, new processes have been developed for the recovery of high-grade spodumene concentrates from high-grade ores using dense medium separation and flotation. For the recovery of mica lithium concentrates from low-grade ore, a flotation process was developed in Russia using the cationic collector ANP-2 and Oxifos-B as an additional collector. Low-grade ore containing 0.14% of lithium oxide was processed into a 2.7% Li2O concentrate. New hydrometallurgical lithium concentrate and ore processes are developed to avoid high-temperature (>1000 °C) roasting. The Sileach process (Australia) includes leaching of lithium ore with sulfuric acid in the presence of a halogen-containing component at a temperature of 95-115 °C. In the Russian process, lithium is recovered into an alkaline solution from low-grade spodumene ore in a pressure alkaline leaching environment (250 °C, NaOH concentration > 300 g/l). The developed concentration and hydrometallurgical methods will allow to design on their basis efficient processes for recovering salable products for hi-tech industries from lithium ores.INTRODUCTION Lithium has many unique and important properties. It is the least dense hard metal. Its alloys have some of the highest strength-to-weight ratios. Lithium has the lowest melting point of all known solid elements and is used as a highly-effective heat transfer medium. The high demand for lithium is due primarily to its unique electrochemical potential and low thermal expansion coefficient. It is used in the production of glass and ceramics, in petrochemicals, metals, medical and other industries. Since the late 20th century, the electronics industry has been the largest consumer of lithium. In recent years, lithium has attracted much attention also as an important component of ultra-lightweight electronic devices. It is also the preferred metal for electric batteries used in mobile electronic devices, vehicles, household power generators, making it an important resource for the development of environmentally friendly technology. Leading automotive brands have ambitious plans for the production of electric cars — Tesla Motors, VW, Toyota, GM, BYD Auto. It is expected that the production of electric vehicles alone will triple the demand for lithium by 2025. A sharp increase in the production of lithium is expected. Lithium has all the prerequisites to become a strategic resource of the 21st century. (Deutsche Bank, 2016; Bradley et al, 2017)"

Jan 1, 2018

By Jiongtian Liu, Jianjun Wu, Yongzhou Wan, Li Feng

"Mechanical Thermal Expression (MTE) is a developing non-evaporative lignite dewatering technology. It has been shown to effectively dewater high moisture content in low rank coals via the application of mechanical force and thermal energy at elevated temperatures. In this paper, the dewatering behavior of Yunnan Xiaolongtang lignite during the MTE-process was studied. Furthermore, how variations in temperature and pressure during the MTE process affect the surface oxygen functional groups and pore structure were also discussed using Fourier transform infrared spectrometer (FTIR) and mercury intrusion porosimetry (MIP). Increases in MTE temperature and pressure resulted in significant reductions in residual moisture content and moisture holding capacity, along with the increase of fixed carbon content and reductions of other elements content, especially oxygen content, which have been largely attributed to the destruction of the surface oxygen functional groups and porosity in lignite. The optimized technology conditions are temperature 150~220°C and pressure 7~10MPa. The residual moisture content of the lignite treated by MTE under the conditions of 200°C and 10MPa is decreased to 8%, while the dewatering rate exceeds 76 % and the calorific value approaches 22 MJ/kg. The experimental results offer a deeper understanding of the influence of process parameters on the lignite stuctures and properties. The reduction in residual moisture content, surface oxygen functional groups and pore volume under increasingly severe MTE conditions are suggestive of the structure changes that accompany increased coalification (rank) within the lignitic range."

Jan 1, 2014

By V. V. Lodeischikov

This paper covers some problems of treatment of complex gold ores and concentrates containing copper, lead, zinc, antimony and uranium. All these metals may present in ores both as major and associated components. The paper suggests recommendations for early determination of relative value of the metals in ores, which largely contribute to the selection of concentration and metallurgical flow sheets. The focus of this work is on treatment of complex ores in gold plants. The metal extraction technologies used by such gold plants are typically aimed at maximum gold recovery. Therefore, production of base metals as by-products requires significant updating of the existing process flow sheets based on economic, environmental and other considerations. At the same time, cooperation between gold plants and base-metal plants is of great importance. This paper provides an overview of worldwide existing and innovative processes of base metals extraction from complex and refractory gold ores.

Jan 1, 2014

By A. A. Lavrinenko, N. I. Gluhova, L. M. Sarkisova, D. V. Makarov

"The purpose of the study is to study the feasibility of using sodium diisobutyl dithiophosphinate (DDP) to enhance the recovery of platinum group elements from low-grade refractory copper-nickel ores characterized by a portion of nickel and platinum group elements (PGEs) locked in the dominant sulfide mineral — pyrrhotite. These ore characteristics dictate the need to produce a bulk PGE-containing sulfide concentrate due to the difficulties of producing selective concentrates without a significant loss of the metals.New data on the adsorption and flotation performance of DDP-containing collectors were obtained by measuring the electrode potential, hydrophobicity of the sulfide mineral surfaces and by means of extraction spectrophotometry and flotation studies. The interaction between DDP, pyrrhotite, and pentlandite leads to the formation of surface hydrophobic layers consisting mainly of disulfide and a small amount of metal compounds. These adsorption layers are formed by the reaction with butyl xanthate. In the case of cooperite, DDP reacts with the surface, forming not only disulfide, as in the case of butyl xanthate, but also a complex platinum compound. DDP-containing agents demonstrate stronger collecting properties with respect to sulfide minerals of copper-nickel ores compared to butyl xanthate, which is explained by a stronger hydrophobizing effect and foaming properties.The addition of a combination of DDP-containing agents and butyl xanthate at a ratio of 3:1 for the recovery of sulfides and PGEs in the bulk flotation of copper-nickel ore made it possible to improve the recovery of Ni, Pt, and Pd by 13.6, 9.2, and 9.4%, respectively, relative to the recovery achieved in flotation with butyl xanthate.Bulk flotation with the addition of a composition of DDP-containing agents and butyl xanthate allows the most complete recovery of all valuable elements and is the only technologically feasible method for processing of lowgrade ores, when it is impossible to produce without loss high-grade selective concentrates suitable for smelting."

Jan 1, 2018

By A. O. Gapchich, T. N. Matveeva, N. K. Gromova

"Tin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. The aim of the work is an experimental study of the modification of the surface of sulfide minerals and cassiterite by stable metal-collector complexes to increase extraction of fine tin, silver, copper and other metals from complex tin ores. Triamide cyanuric acid (TCA) was studied as a thin silver flotation modifier. Thermophilic polymer with a functional group of phenylphosphine TMPPh was used as a selective flocculant. For experimental studies of the physical and chemical effects of collecting agents on the surface of minerals the following analytical techniques were used - the analytical scanning electron emission ASEM (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy, measurements of electrode potentials of mineral anthills by potentiometric titration, monomineral and pulp flotation. New data on formation of the adsorbed layer of DBDTC on the surface of chalcopyrite, galena and arsenopyrite were obtained, and the dimensions of the reagent films and the strength of their adsorption. The indiscriminateness of cassiterite to DBDTC ensures its selective separation into a chamber product during the flotation of sulfides. It is shown, that modification of the sulfide surface by stable complexes Me-DBDTC and Ag-TCA-TMPPh will increase the recovery of non-ferrous metals and silver into a collective sulfide concentrate and will provide a high-quality tin concentrate for flotation of tin sulfide ores.The studies were perfomed with the aid of the Russian Science Foundation (Project No. 17-17-01292).INTRODUCTIONTin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. In this regard, it seems advisable to use new varieties of flotation reagents in order to increase extraction of finely dispersed tin, silver, copper and other non-ferrous and precious metals from multi-metal tin ores (Bocharov and Ignatkina, 2007; Khanchuk etal., 2012; Wu and Zhu, 2006; Yusupov etal., 2016)."

Jan 1, 2018

Coal preparation plants usually operate with water in a closed circuit mode. In this practice, large quantities of water is continuously being recycled. To compensate the natural losses, only small quantity of fresh make up water is added into the circuit. As a result, a gradual build up of residual concentrations of flotation reagents (frothers, collectors, coagulates etc.) take place in the water and the concentration levels of the contaminants increase. Besides, the recycled water accumulates higher amounts of total dissolved components (1600 ppm) and hardness (740 ppm) than the fresh water. Nearly 80 ? 85% of the process water used in a coal preparation plant is utilized in treating the coal fines in flotation circuit. The presence of certain alkali earth metal ions (e.g., Ca++, Mg++) may adversely affect the flotation performance as they precipitate sparingly soluble hydroxyl complexes on the coal surface and change its surface charge. These studies showed that the use of recycled water in flotation has a significant effect on the selectivity and kinetics of the flotation process because, the dissolved compounds, both inorganic and organic, alter the chemistry radically. By treating the recycled water through a softening process, the concentrations of alkali earth metals and hardness were reduced significantly. The concentration of alkali earth metals and hardness were reduced to 10 ppm and 35 ppm respectively in the softened recycle water. From the selectivity studies, it has been observed that the flotation yield and recoveries increased by four to seven units by softening the recycled water. The kinetic studies indicated that the clean coal particles followed first-order kinetics. The kinetic parameters namely, flotation rate constant (k) and maximum recoveries (R8) of flotation, were found higher with softened recycle water than the recycled water. This reduces the residence time in the flotation cell and thereby, increases its productivity. Keywords: coal flotation, hardness of water, water chemistry, softening process, selectivity, kinetics, flotation rate constant and maximum recovery

Sep 1, 2012

By Sathyaprasad Nanjundaiah

The Paper intends to showcase a framework for spatial data collaboration from multiple sources of data, in order to create a single source of truth across the Organization. The framework is targeted to reduce the data duplicity, re-work, time loss due to search of required data and hindrances to fetch or transfer data from various data sources. The spatial data collaboration will provide a single window view of the entire organization with respect to its operations, management, sales, customers and competitors on a spatial reference across various regions in the World. Large Organizations with cross-country operations can standardize the use of spatial data through this framework for ease of data access, increasing the data reliability / integrity and better / on time decision making. Keywords: spatial data, GIS, collaboration, framework, mining, ESRI, tab files, shape files, ETL, reliability, integrity, interoperability, geo data, geo database, single source of truth

Sep 1, 2012

By A. Ceylan

Pyrite is present as a gangue mineral in most of complex sulphide ores and most of time it is removed as a tailing. However, beneficiation of pyrite from tailings could be important because of its economical value and for the environmental concern. This paper presents a research for the enrichment of pyrite from copper plant tailings, Siirt-Madenköy/Turkey, by flotation. Siirt-Madenköy copper mine is operated by Park Electric Production Mining and Industry since 2005. In order to obtain the pyrite from Siirt-Madenköy copper plant tailings, laboratory test work has to be done to determine the type of reagents, the flowsheet, and the size of plant. The objective of the company is to develop a pyrite flotation circuit for concentration of pyrite from tailing dam to obtain 500.000 tons/year pyrite concentrate. There are about 3 million tons tailings that containing pyrite in the tailings dam. Experiments were carried out with three different types of tailings from the plant and the pyrite concentrate with 46% Fe and 90% recovery has been obtained. Therefore, this study shows that high grade pyrite with high recovery can be recovered from the tailings.

Sep 1, 2012

By Ye Chen, Jianhua Chen, Meng Liu, Yuqiong Li, Xiao Mu, Cuihua Zhao

"Sulfidization-amine is the most effective method for the recovery of smithsonite (ZnCO3), however the interface interaction details remain unclear. The sulfidization-amine flotation mechanism of smithsonite has been studied by Density Functional based Tight Binding (DFTB+) method in this paper. The slab model of ZnCO3 (101) surface was built and the adsorptions of a monolayer of HS- and S2- ions were conducted to model the sulfidization effect on the ZnCO3 (101) surface adsorption. DDA hardly interacts with the hydrated ZnCO3 (101) surface. Under the low concentration of Na2S, HS- ions form a Zn-SH-SH structure on the ZnCO3 (101) surface, which hinders the interaction between DDA and surface Zn atoms. Under the high concentration of Na2S, a layer of ZnS is formed on ZnCO3 (101) surface, which is favorable for the adsorption of DDA on the surface. This is consistent with the flotation practice where smithsonite flotation requires a large amount of sodium sulfide. The results could provide a microscopic investigation into the sulfidization-amine flotation mechanism of smithsonite.INTRODUCTIONSmithsonite (ZnCO3) is an important and typical oxide mineral of zinc. It is a semi-soluble salt mineral with a solubility product constant of 1.46 × 10-10 (Weast, 1973). The most common and effective method to recover oxidized zinc ores is froth flotation (Caproni et al., 1979; Pereia and Peres, 2005; Kashani and Rashchi, 2008). It is well known that the flotation of oxidized zinc minerals is much more difficult than the flotation of zinc sulphide minerals (Hosseini and Forssberg, 2007).The recovery of zinc oxide ores with poor floatability attracts more and more attention due to the depletion of easy-recovered of zinc sulfide ores.Sulfidization-amine flotation, which using Na2S as sufidizing agent and amine as collector (Mckenna et al., 1949; Rey, 1954; Abramov, 1961; Rey, 1979; Hosseini and Forssberg, 2007). This method is the most successful technology used for zinc oxide minerals flotation in large-scale industrial applications since it was invented in the 1950s (Önal et al., 2005; Pereira and Peres, 2005). There have been numerous experimental researches on the sulfidization-amine flotation of smithsonite. Shi et al., (2013) studied solution chemistry of smithsonite flotation system. Feng and Wen (2017) studied the formation of zinc sulfide species on smithsonite surfaces and its response to flotation performance. Wu et al., (2017) investigated the sulfidization behavior of smithsonite with the use of zeta potential, inductively coupled plasma (ICP), scanning electron microscope (SEM), and X-ray photoelectron spectroscopic (XPS). Their measurement results confirms the chemisorption of sulfur ions and the formation of ZnS film on the smithsonite surface after Na2S treatment, however the influence of HS- ions on the surface and the influence of sulfidization on the amine adsorption have not been discussed."

Jan 1, 2018

By Y. M. Zhu, G. C. Gong

"The influences of citric acid (CA) on the flotation behavior of cassiterite using styrene phosphonic acid (SPA) as the collector were studied via single mineral flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations in this paper. The results of single mineral flotation tests revealed under the conditions that pH=4 and the dosage of SPA 100 mg/L, the recovery of cassiterite reached 76.78%. The addition of 20 mg/L AC decreased the recovery by 12.42% at pH=4. Contact angle measurements demonstrated the adsorption of CA prior to SPA made the cassiterite more hydrophilic. The results of zeta potential determinations and solution chemistry calculations indicated the chemisorption of C6H7O7- and C6H6O72- filled parts of the Sn site on cassiterite surface and prevented the SPA from getting adsorbed. The hydrophilic effect of AC was stronger than the hydrophobic effect of SPA and the flotation of cassiterite was crippled. INTRODUCTION Tin is an important metal which is widely used in medical instruments, marine engineering materials, electronic and electrical devices, welding, weapon manufacturing and organotin compounds industries (Angadi et al., 2015). Cassiterite is the only mineral from which the tin can be extracted, thus it is of great importance to efficiently exploit the cassiterite mineral. Flotation is an indispensable method for the recovery of cassiterite (Li et al., 2015). However, cassiterite is usually in association with many other gangue minerals which are of similar floatability, such as quartz, calcite, fluorite, iron oxide, wolframite, scheelite and tourmaline (Sreevinas, 1997). So some modifiers are necessary in the cassiterite flotation process. The amounts of the modifiers used in the flotation must be judicious and the overmuch modifiers may cripple the recovery of cassiterite (Parsonage et al., 1987). Nevertheless, the research about the effects of the modifiers on the flotation behavior of cassiterite has been rarely reported. In this paper, the influences of citric acid (CA) on the flotation of cassiterite using styrene phosphonic acid (SPA) as the collector were investigated by flotation tests, contact angle measurements, zeta potential determinations and solution chemistry calculations."

Jan 1, 2018

By N. Syna

The selection and preparation of activated carbon suitable for specific application can often involve exhaustive adsorbent preparation and testing. This work examined an emerging technique based on modelling the correlation of observed adsorption capacity to the carbon characteristics as a means of decoupling the roles of carbon textural and surface chemical properties. The insights to these specific roles are then used in tailor-making adsorbents and in establishing the optimal carbon properties for specific application. In this study, a series of activated carbons prepared from bagasse by physical and chemical techniques and commercially available carbons were used in developing the models. These carbons were tested for the adsorption of thiourea-gold (I) chloride complexes. Thiourea is an important alternative gold lixiviant with the potential to address current ecological and safety concerns in the extraction of gold. A four-component model, which correlated the adsorption gold capacity to carbon textural and surface chemical properties, was proposed. The model fit was assessed using multi-linear regression and a partial F-test. This was followed by goodness of fit test achieved through r2, adjusted?r2 and mean square error (MSE) values. The results suggest the adsorption of the gold-thiourea complex is strongly influenced by the internal surface area and pH of the carbon. Tailor-made activated carbon from bagasse showed adsorption gold capacities of up to 198 mgAu/g adsorbent, demonstrating the potential of bagasse as a precursor for gold adsorbents and of this empirical modelling approach in developing adsorbents for metal recovery.

Jan 1, 2014

By N. Pradhan

In the Sukinda valley, Orissa, India, a large quantity of overburden material is generated during the mining of chromite mineral (on average 10 tons for every ton of ore). The overburden hereby depicted as ?lateritic nickel ore? contains on an average 0.5% Ni. IMMT Bhubaneswar is working on this material for extraction of nickel and cobalt. But for better recovery of metal values, thermal activation or thermal reduction of ore is required. An alternative biotechnological route for reduction of ore is hereby attempted. An anaerobic dissimilatory Iron (III) reducing bacterial consortium (here denoted as IRB), capable of imparting iron phase changes in the lateritic nickel ore was established which improves the subsequent extraction of co-precipitated Co (III) and Ni (II) from the ore. In this study, properties of thermally and microbially reduced lateritic nickel ore are compared vis-à-vis original ore. Due to the phase changes, original light brown color of the lateritic nickel ore changes to dark brown on IRB treatment. This dissimilatory reduction of ore leads to formation of some magnetic particles, which were separable by hand held magnet. Roasting and IRB treated ore on acid leaching with H2SO4 show about 45 % and 36 % leaching of nickel ore compared to about 18 % leaching from the original lateritic ore. If bacterial reduction method is successful, cost intensive method of ore roasting process can be eliminated. Thus, it is possible to make use of dissimilatory iron reducing bacteria for recovery of valuable metals from off grade iron ore/ laterites. Keywords: lateritic nickel ore, bacterial reduction, thermal reduction, dissimilatory fe (iii) reducing bacteria

Sep 1, 2012

By Sravya Kosaraju, Christian Ekberg, Stefan Allard

Li-ion batteries are now used in electric vehicles (EVs), plug-in hybrid vehicles (PHEVs) and, hybrid electric vehicles (HEVs). Nanostructured Li(NiyMnzCo1-y-z)O2 is one of the more popular cathode chemistries for automotive Li-ion battery, due to its enhanced properties such as large surface area, short diffusion length, enhanced ionic and electronic conductivity, improved mechanical strength and structural integrity [Pan et al, 2013]. Recycling of Li-ion batteries helps to mitigate environmental effects of virgin metal extractions along with improper disposal of end of life batteries. To fulfill these objectives of the recycling, recovery of pure streams of the involved metals should be considered. In this study, the batteries were first discharged and dismantled in an inert atmosphere (Ar). The electrodes were then heat treated in a box furnace. This was done in order to break the chains of the adhesive (PVDF) and consequently separate the metallic substrates Cu and Al from the electrochemically active compound. This heat-treatment also helped to simplify the dissolution of the metal constituents in the electrochemically active compound from the cathode in the acid leaching process. Solvent extraction was chosen to achieve separation and recovery of metals with higher purity from these leachates. In the scope of the present work, a complete process from the point of dismantling to separation of constituent metals using solvent extraction was studied.

Jan 1, 2014

In the present work, the flotation behaviours of zircon, rutile and ilmenite using sodium oleate as collector in absence and presence of depressants were thoroughly investigated. The maximum in the flotation recovery of any of the above minerals falls within similar pH ranges. A range of inorganic and polymer depressants were examined in order to improve the separation of zircon from rutile and ilmenite. Optimum values of conditioning pH and depressant concentration to achieve maximum recovery and best selective floatability of zircon were obtained. Selective flotation of zircon from Ti-bearing minerals was anticipated from single mineral experiments under different pH values, depressant and collector conditions.

Jan 1, 2014

By V. A. Chanturiya

In Pt- and Au-keeping complex ores processing, about 10% ~ 15% of noble metals are lost with true tailings that are due to low floatability of Pt- and Au-keeping minerals by the conventional collectors. With the aim to achieve the effective recovery of noble metals at flotation of Pt-Cu-Ni and Au-keeping ores organic complex reagents keeping electron-donating atoms of nitrogen, oxygen, sulfur or phosphorus may be offered as selective collectors for the indicated minerals. These rea-gents tend to form complex compounds with PGM. Besides this, Cu-Ni-Pt and complex Pt and Au carbonated mica ores are characterized by finely disseminated (up to nanometer size) mineral forms of Pt in multivalent states. In this connection, the use of a combination of the strong ionic collectors with nonionic reactants that are capable to derivate complex compounds with multivalent PGM seems to be expedient for this type of ores. In the research new complex reactants were tested such as cyclic alkylene-trithiocarbonates, oxyalkyl butylxanthogen acid ethers, a combination of the collectors ? mercaptobenzothiazole (MBT) and dialkyldithiophosphates (DTP). Sorption and flotation tests were made with monomine-ralic samples of chalcopyrite, pentlandite, pyrrhotite, pyrite, and Pt-Cu-Ni sulfide ore samples. Sorption properties were examined by the extractive UV spectrophotometric method and potentiometric measurements. To indicate a structure of modified xanthate solutions the method of a thin-layer chromatography (TLC) was applied. The chromatographic behavior of the basic components of modified xanthate solution ? ButX, cyclic propylene-trithiocarbonate (PTTC), diethyl-dithiocarbamate (DEDC) and the product of its modification ? oxypropyl-S-ether of dithiocarbamatic acid was studied on plates ?Silufol UV ? 254?. The composition of organic solvents and its ratio in a mobile phase was deter-mined for simultaneous chromatography of the main components of a reaction mixture. It was found that operating selectivity of MBT, DTP and cyclic alkylene-trithiocarbonates incorporated in modified xanthate in relation to Pt-Cu-Ni and Au-containing sulfide minerals might be explained by an electoral sorption of this nonionic collector on a surface of the minerals studied. It was demonstrated that the application new reagent modes with the use of a combination of designed complex reactants helped to increase the extraction index of Pt- and Au-keeping minerals from complicated ores.

Jan 1, 2014

By V. F. Petrov, E. P. Olberg, S. V. Petrov

"The study was carried out using process solutions produced during cyanidation of gold-bearing concentrates from a gold-processing plant. It was found that the water contained a significant portion of thiocyanate (7910.0 mg/L), cyanide was virtually not present. The metals occurred primarily as iron (355.0 mg/L) in the form of ferrocyanide. Cyanide recovery was conducted using an ozone treatment process with reactors developed by the Environmental Department of Irgiredmet. The process design ensured complete utilization (100%) of O3, thus equipment operation safety increased.The recovery of free cyanide from thiocyanate was 76.6%, which corresponded to 5.12 kg of NaCN (100%) per 1 m3 of solution. Recovered NaCN can be used for recycling in hydrometallurgical processes.The operating costs estimation showed that the production cost of a tonne of recovered cyanide was US$1288.7, considering the prices of energy and commercial sodium cyanide in Russia in 2017, i.e. recovered cyanide is cheaper than commercial cyanide by 55.8%.INTRODUCTION Depletion of oxidized gold-bearing ores readily amenable to cyanidation has shifted focus to large-scale processing of primary ores with high sulphide content. Primary ores processing flow sheets involve gravitational and/or flotation concentration with subsequent treatment of produced gold-bearing concentrates. Typically, concentrates reporting to cyanidation contain considerable amounts of sulphur that can interact with CN- and further formation of SCN-. The use of refractory gold liberation methods (bacterial liberation, ultra-fine grinding) provides activation of this side reaction up to complete consumption of free cyanide in a short period. This makes water recycling unviable and impractical.The interaction of the sulphur content in concentrates and cyanide contributes substantially to consumption of NaCN required for efficient gold recovery. Inappropriate consumption of the main reagent achieves dozens of kilogram per tonne of material to cyanidation, and reaches approximately 100% when gold is recovered from activated sulphide-containing products (e.g. by ultra-fine grinding)."

Jan 1, 2018

By Brian Loveday, Sandile Nkwanyana, Indresan Govender

"Recent batch experiments by the authors in a pilot scale ball mill (Ø = 0.6m) have demonstrated that a partial replacement of the ball charge by pebbles (25 % pebbles; 75 % steel balls) optimally reduces the ball and power consumption without altering the rate of production of fine material (passing 75 microns). At higher pebble volumes, the production rate of fines was reduced progressively. With the 25/75 composite charge a saving of 13 % in power consumption was achieved, and a saving of 25 % in steel ball consumption is implied. A partial replacement of steel balls by pebbles reduces the overall density of the grinding media in the charge. Taking into consideration that the production rate of fines is usually proportional to the bulk density of the charge in the mill, it would be expected that a composite charge (e.g. 25/75) would coarsen the grind and consequently reduce the rate of production of fines. Pebble wear contributes a small proportion of fines and it doesn’t provide a full explanation of why the 25/75 composite charge has no (or minimal) adverse effects on the rate of production of fines. Clearly, the production of fines across the mill is directly related to the shear and compressive power dissipation density. Accordingly, we hypothesise that the spatial power dissipation distribution meeting the minimum requirements for fines production— at the so-called active regions—are equivalent, or minimally comparable, for both the 25/75 composite and 100 % ball charge operating conditions. To test the hypothesis, we performed DEM simulations to analyse power dissipation in the active regions. 1. INTRODUCTION Comminution remains to be the most expensive process in mining operations, particularly because the energy consumed in this process accounts for 30-70 % of the total cost of a mining operation (Nadolski et al, 2014). Optimization of comminution circuits has been focussed on reducing capital and operating costs and maximising throughput capacity. For existing operations, it is often a challenge if the optimization process recommends retrofitting new ‘major’ equipment. The challenge arises from new capital cost and the difficulty of retrofitting in an existing circuit, while maintaining production (Major et al, 2001). Thus, for existing mining operations, optimization of comminution (cost and throughput) is often limited to operating conditions and/or addition of auxiliary equipment (such as pebble crushers, additional screens and high pressure grinding rolls (HPGR)) (McIvor and Greenwood, 1996; Hart et al, 2001; Powell et al, 2015b)."

Jan 1, 2018

By E. R. Bobicki

"Low-grade ultramafic nickel ores, while representing a large potential nickel resource, are difficult to process due to their serpentine content. Microwave treatment is proposed as a technique to improve the beneficiation of ultramafic nickel ores by converting the constituent serpentine to olivine. The present paper reviews the microwave heating response of ultramafic nickel ores and resultant changes in mineralogy, as well as effects on grinding and slurry rheology. Beyond nickel extraction, microwave treatment improves the mineral carbon storage capacity of ultramafic ore tailings, providing a potential source of additional revenue via the sale of carbon credits. The combined positive effects, considered in the context of the whole operation, suggest an economically viable process is possible.INTRODUCTIONAs high-grade deposits become depleted, the processing of low-grade ores has become increasingly important. One such resource is low-grade ultramafic nickel ores. While representing a large source of nickel, these ores are difficult to process due to their serpentine content. Serpentine is a phyllosilicate mineral consisting of 1:1 stacked sheets of silica tetrahedra and magnesium hydroxide octahedra. There are three primary polymorphs: lizardite (platy), antigorite (corrugated) and chrysotile (coiled, fibrous). The anisotropic nature and non-spherical morphology of serpentine particles leads to complex rheology. Suspensions of serpentine minerals, especially those of chrysotile, exhibit high viscosity and yield stress, which can have a negative effect on comminution, flotation and dewatering operations. In flotation, serpentine is known to slime-coat pentlandite, a valuable nickel mineral, and form bubble-fibre aggregates that report to the froth, reducing nickel concentrate grade and recovery. Methods used to counteract the effects of serpentine in processing include desliming, the addition of chemical dispersants, salts or acid, and dilution (Bobicki et al., 2014a). Microwave pre-treatment has been proposed as an alternative way to eliminate the deleterious effects of serpentine in ultramafic nickel ore processing by converting the serpentine to olivine via dehydroxylation, which occurs at 600-700oC (Reaction 1). Olivine is isotropic, consisting of isolated silica tetrahedra linked by octahedrally coordinated magnesium ions, and has the same surface potential as pentlandite at the pH of flotation (~pH 9). Furthermore, since olivine is more reactive to CO2 than serpentine, microwave pre-treatment creates an opportunity to store more CO2 in tailings, an attractive option for mining operations looking to increase their bottom line where carbon pricing exists."

Jan 1, 2018

By A. An. Mushketov, A. Al. Mushketov, N. A. Sopina

"INTRIDUCTION At present, more and more metallized raw materials with a metallization degree of not less than 80% are used in the smelting of steel. The main quantity of this raw material is produced in furnaces of mine type. Advantages of this type of raw materials for metallurgical processing are low levels of harmful and slag-forming impurities and a high content of metallic iron. At the same time, the cost of smelting raw materials and obtaining high-quality steels are reduced. In addition to the undoubted merits of metallized raw materials, there are high requirements for the quality of iron concentrates, which are the starting material for metallization: the mass fraction of acidic oxides should not exceed 3%; The mass fraction of iron should not be less than 69%, mass fractions of harmful impurities (phosphorus, arsenic, sulfur, copper, etc.) should not exceed 0.02%. These requirements are dictated by the fact that the recovery of burned pellets is carried out by gas in a solid phase. In this case, the empty rock and harmful impurities from the metal are not separated and sent to the steelmaking unit, increasing the heat consumption for heating and worsening the quality of the steel. The combined production of high-quality concentrate and metallized raw materials requires a large capital outlay from the enterprise, which in the future can be compensated for by increased profit from the sale of more expensive marketable products. At present, in the territory of Russia and the CIS countries Lebedinsky mining-and-processing integrated works is the only enterprise that carries out the entire chain of operations for the production of metallized raw materials, starting with the production of high-quality magnetite concentrate with a mass fraction of iron of 69.5% and ending with the production of a metallized product in the form of hot briquetted gland. JSC «SSGPO» is the largest iron-processing enterprise in Kazakhstan, which processes about 40 million tons of ore per year and receives 16 million tons of concentrate per year with a mass fraction of iron 66.0-66.5%. The technological scheme existing at the concentrator of JSC ""SSGPO"" includes the crushing of the feed ore to the size of 20-0 mm; dry magnetic separation operation; three reduction stages to a fineness of 90-95% kl-0.071 mm; operation of desliming, wet magnetic separation and filtration of the concentrate. Dry magnetic separation of the feed ore makes it possible to remove from the process of 19.6% of the tailings with a mass fraction of the total iron 12.5%, of magnetite 2.2%. The first reduction stage is carried out in rod mills with the volume of 40 m3 to a size of -1.6 + 0.0 mm. The first stage of wet magnetic separation is carried out in counterflow magnetic separators PBM-P-150/200L. The magnetic product of the first stage of WMS is classified in hydrocyclones; sands enter the second reduction stage into central discharge ball mill 3600 × 5000. Runoff of mills enter on the second enrichment stage in counterflow magnetic separators PBM-P-150/200L. The magnetic product enters the classification of the second stage, forming a closed cycle. Mass fraction of the class -0.071 + 0 mm in classifications runoff of the second stage is 70-75%. The second stage classifications runoff is transported toWMS-III operation in semi-counter separators PBM-PP-120/300. The magnetic product of the third stage enters the classification of the third stage. Granular residue are transported to the reduction of the third stage into central discharge ball mill 3600 × 5000. The mill runoff enters the third stage of classification, forming a closed cycle. Classifications runoff of the third stage enters on deslimation. Deslimed product is sent for fine screening to the crasher «Derrick» 2SG48-60W-5STK with a cell size of 0.1 mm. Top size of crasher is sent to regrinding. Undersize with a mass fraction of the class -0.071 + 0 mm 90-95% is fed to the wet magnetic separation of WMS-"

Jan 1, 2018

By B. W. Zhao

Quantitative analysis of minerals composing in ore is primary in process mineralogy, a veracious quantification and analysis is very crucial to optimize or design a beneficiation process, especially for a low grade and complicated ore. This paper will discuss a SEM-EDS based quantitative analysis developed in JKtech Australia through an example from Jinchuan lean ore. For a low grade, com-plex intergrowths and texture lean ore, chemical phase analysis of value minerals and identification by optical microscope are very essential, unite the SEM-EDS based quantitative analysis, we can understand exactly the lean ore, explain and quantify the process performance.

Jan 1, 2014