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By M. V. S. Cavalcante

The quality of iron ore pellets, represented in terms of parameters such as cold compressive strength (CCS) and Tumble Index (TI), has a strongly influence on the productivity and energy of reduction furnaces like the blast furnace and on the quality of hot metal or liquid iron. The main objective of pelletization operations is to produce iron ore pellets of desirable specifications and ensure high levels of plant productivity and energy efficiency. Advanced process control of an industrial iron ore pellet induration process using a soft sensor for pellet quality and fuzzy-logic based control algorithm is described in this paper. The pellet quality soft sensor consists of a rigorous mathematical model of the induration process and a statistical model for the pellet quality parameters. The mathematical model is based on the fundamental principles of heat and mass transfer between gases and pellets, kinetics of drying and condensation of moisture, combustion of coke, calcination of limestone, and melting and solidification of pellets. The predictions of wind-box temperature profiles are in close agreement with the measured profiles. The time-temperature profiles of the pellets during induration, along with raw material characteristics and induration process operating conditions, are used as inputs to the quality model to predict cold compressive strength and the Tumble Index. The predictions of the quality soft sensor along with the rules based on fuzzy-logic derived from simulation results and operator experience are then utilized to control the induration process to achieve precise control of the quality parameters and to optimize the induration process in terms of fuel efficiency and productivity. The mathematical model is also utilized as a soft sensor for temperature, moisture and composition profiles of pellets and gases. Results of implementation of this model-based control strategy on an industrial scale induration process will be presented. Keywords: iron ore, pelletization, simulation, process control, optimisation

Sep 1, 2012

By S. H. Morar

Froth stability is widely recognized as a key driver of flotation selectivity. It is well known that froth stability is affected by the type and quantity of surface active reagents present (frothers), and the concentration and hydrophobicity of solid particles present. While some studies have been performed on the effect of frothers on froth stability in three-phase systems and the hydrophobicity of particles present, very little work has been performed on the effect of solids loading on froth stability. This may be due to insufficiently robust measurement techniques. This paper investigates the use of a new machine vision measurement to measure solids loading, and the relationship between this measurement, bubble size, and bubble burst rate on the froth surface. Keywords: froth flotation, machine vision, solids loading

Sep 1, 2012

There are interactions between different minerals from the same ore, minerals and grinding media, and the electrochemical conditions present in the system. Grinding in steel rod and ball mills is a common practice in minerals processing. It is accepted, that the electrochemical interactions between the grinding media and minerals in a grinding mill, influence the corrosive wear of balls/rods and the surface properties of the ground minerals. A complex massive sulphide, Cu-Zn, TAKNAR, Iran, was used for all the experiments. The aim of this study was to investigate the effect of grinding media (dry or wet) on the pulp chemistry and recovery of Cu and Zn in bulk concentrate. 1100 g of ore samples were milled, and mill products with d80=85 and 75 micron in wet and dry grinding methods were produced. Rougher bulk flotation experiments were performed with 550g ore samples, at 30% solids. SIPX in conjunction with Aero238 in 1:2 ratio (48 g/t), was used as mixed collector system, and copper sulphate (200g/t) and MIBC (20 g/t) were employed as sphalerite activator and frother. Lime and High purity Oxygen gas were used for adjusting pH at 8.5 and aeration. The results showed that, more positive pulp potentials were measured when the feed had been ground in a dry environment, and the difference in pulp potentials between the dry and wet ground feed was approximately 250 mV after the grinding stage. In dry grinding method, the recovery of Cu and Zn increased approximately 5 and 10%, respectively. In addition, in dry ground samples, the volume of middling and coarse particles (+100 micron) were more and Dry ground flotation feed had better agreed with using a mixture of collectors. After using copper sulphate, pulp potential increased about 50 mV in dry and 75 mV in wet grinding methods. Keywords: grinding media, pulp potential, Cu-Zn massive sulphide, bulk flotation

Sep 1, 2012

By P. V. Malyarov

"This paper examines the grinding and wear processes in drum mills. A summary of the industry’s long-term experience with the proposed linings is presented. A method is proposed for assessing the efficiency of the grinding energy distribution between the successive stages. A case study is presented of grinding energy redistribution at Talnakh Concentrator by replacing spiral classifiers with a drum-type hydraulic screen. The problems of the kinetics of grinding processes in ball mills and semi-autogenous (SAG) mills are examined. It is demonstrated that in ball mills the feed particles are disintegrated by triaxial compression in the mill zones where discrete slippage of the charge occurs at major force interactions between the layers. Mechanism underlying increases in the specific energy consumption in grinding circuits based on SAG mills is shown.The problem of improving the throughput and reducing the specific energy consumption in mineral feed grinding is highly relevant because of the significant energy intensity. Up to 80% of the consumed energy is used to disintegrate ore fed into the drum mill. At all development stages of the drum mill grinding theory, the researchers have paid a great deal of attention to studying the patterns of the charge motion and the kinetics of the feed particles disintegration processes. In [1], it was shown that, due to the slippage between the charge layers being lifted, drum mills at concentrator plants operate in a mixed cascade and waterfall mode. A feature of the mixed mode is the toe zone, where the charge contacts the lining and the transition to a circular path takes place. Studies of the charge motion in the toe zone made it possible to develop a method for designing cross-sectional profiles of lining plates [2] for ball mill drums. The method is based on the principle of interaction between the balls and the lining, where the non-working rear surfaces follow the relative motion path of the balls before impacting the lining, while the working surfaces are orthogonal to the rear ones. Lining with the proposed profile provides contact with the charge and slippage-free transition to a circular path. This ensures an longer service life of the lining, a reduction in specific energy consumption, and an increase in the mill’s feed rate. The proposed method is applicable when designing lining plates of various materials. Steel liners with the proposed profile have been successfully operated [3] for more than 40 years at a number of projects in the industry."

Jan 1, 2018

By Vishal Shukla, Ashok Kumar, Manas Ranjan, D. Chakraborty, Narayan Sharma

Jigging has a very important role in mineral processing Industry. Upgrading of Iron Ore by jigging has been an emerging trend. A detailed investigation is carried out to understand the influence of Jig feed granulometry and bed height during jigging operation. Noamundi jig plant data shows that variation in jig feed granulometry, feed quality and bed height are major contributors to fluctuation in jigging performance. At Noamundi the feed size (-10.0+0.5mm) fraction is used for fines jigging operation. To understand the effect of granulometrey on jig plant performance such as yield, separation efficiency and Fe recovery. In this context The performance of jigging was evaluated by daily average data from jig operation was used to study the influence of feed distribution on jigging performance .Coarser fraction (+6mm) has a positive influence , whereas fines fraction (-0.5mm) tends to lower performance . During Jigging rearrangements of Particles takes place due to an alternate expansion and compaction of Jig Bed .These particles are arranged by increasing density from top to bottom. During the particle stratification, Jig bed physically cut at desired horizontal particle density plant to separate the desired product. Investigation shows that optimum bed height is required at different Jig feed quality to achieve desired product quality, maximum separation efficiency and Fe recovery. This Paper will illustrate role of granulometry and Bed height control on Jigging plant performance.

Jan 1, 2014

By Yuhe Tang

High Gradient Magnetic Separator with Horizontal Magnetic Line is a new type High Gradient Magnetic Separator product. It has many specific advantages, such as water-air joint discharging technique, double pulses pulp dispersion technique, multi-magnetic gradient for collecting matrix with different diameter rods, better discharging rate with the especial matrix dispose, high separating accuracy and wide applicability. In this paper, the author makes a description of High Gradient Magnetic Separator with Horizontal Magnetic Line, and puts its emphasis on analyzing industrial production data using high gradient magnetic separator with Horizontal Magnetic Line to separate weakly magnetic minerals. It is found that as the rougher for weakly magnetic minerals separation, High Gradient Magnetic Separator with Horizontal Magnetic Line has more stable metallurgical performance and cheaper running costs than other types of High Gradient Magnetic Separator when the properties of the ore change greatly and there is in the case of embedded fine particle size distribution. Keywords: high gradient magnetic separator, self cleaning technology, horizontal magnetic line, water air discharging technique

Sep 1, 2012

The Arctic is a region of special economic, geopolitical, research, socio-ethnic, and defense interests of both Russia and other countries of the Arctic zone. Introduction of innovation technologies at ore-processing factories is a direct responsibility of the state and this problem should be solved on the basis of coordination of interests of different stakeholders. The task of elaboration of scientific principles of rational state regulation in the North is very topical. Innovations require considerable investments first of all from private capital. However as an investment object innovations are not attractive for investors as they require large expenditures for long-term projects, and they are connected to high risks because market incentives form striving to get quick profits of private companies and result in a certain behaviour strategy while innovations need ?long money?. Under such conditions without state regulation of investment and innovation activities development of the mining sector in the Arctic practically has no prospects. At innovation development of mining enterprises economic growth is provided at the expense of active state innovation activities. The elaborated strategy of ore-processing enterprises should correspond to the modern paradigm of the ore-processing industry development which is not only for extraction of minerals but also for multi-profile structure having comprehensive use of the resources on the rational basis intended for rational complex utilization of mineral resources of the AZR which by the definition includes maximally full use of the whole aggregate of resources on the economically rational basis with obligatory environmental with resource reproductive and socio-economic functions and deterrents. The main principle of creation of innovation technologies is to obtain more products of higher quality with minimal costs. This allows increasing ?productivity of the resources? several times. This principle makes increasing productivity of the resources the most important and in this case efficiency of use of the resources brings extra profits at the expense of lack of new costs such as payment for protection and utilization of wastes. According to the economic theory only ratio between demand and supply is able to fix optimal proportions in economy and to give necessary signals for investment activities of mining enterprises. In this context market for minerals and increase of mineral resources productivity do not create incentives for investment activities without which neither sustainable economic growth nor solution of macroeconomic tasks are possible. Nevertheless countries should not reject this idea in spite of economic efficiency of the enterprises. Extraction degree of useful components and especially oil in the Arctic zone is one of the lowest in the world. This can lead to crisis of oil industry and other mining sectors. The reason for that is lack of a state policy of realization of innovation technologies in the mining sector in the Arctic.

Jan 1, 2014

By F. L. Mentg

The utilization of acid leaching tailings was studied. It is obvious that the Fe in acid leaching tailings can be leached into solutions as Fe2+. In this paper, the influence of conditions, including the concentration of ferrous sulfate, pH, temperature and velocity of air flow was investigated. The optimum conditions for preparing seed crystal are as follows: the concentration of ferrous sulfate is 20 g/L; pH is 9.5~10; reaction temperature is 10~20?; velocity of air flow is 0.4m3/h. The optimum conditions for preparing iron oxide red are as follows: the concentration of ferrous sulfate is 5 g/L; reaction temperature is 80~85?; velocity of air flow is 0.13m3/h. At last, the product of iron oxide red could be prepared by ammonia method.

Jan 1, 2014

By Atul Kumar Bhatnagar

TATA STEEL is the pioneer in coal beneficiation in India. The first coal beneficiation plant was set up in 1951 at West Bokaro and subsequently in 1953 in Jharia. Over the years more beneficiation capacity was added by setting up new coal washeries in both West Bokaro and Jharia, the coal divisions of Tata Steel. currently the beneficiation capacity available is 8.5 mtp aappx Being a captive supplier supplying the coking coal as per demands of our steel works is challenging in the sense that the intent is to leverage the captive raw material advantage and select the best strategy for maximizing value up to steel making. The beneficiation plants were designed to produce clean coal up to 17% ash. With the demand of increasing productivity at the blast furnace the clean coal ash was lowered. subsequently the processes were audited and efficiency improved. The next challenge was to improve the throughputs in the existing plants to maximize the clean coal production. The upgradation was designed in house and implemented to upgrade the plant from nameplate capacity of 2.1 mtpa to 4.5 mtpa while the yearly production targets were also achieved. The presentation will detail the different phases of improvements, process followed, challenges faced, and the results as achieved in the process. Keywords: coal beneficiation, India, coal washeries, beneficiation plants XXVI INTERNATIONAL

Sep 1, 2012

By Stoyan N. Groudev, Ioannis Paspaliaris, Irena I. Spasova, Kostas Komnitsas

"Acid mine drainage waters generated in the uranium deposit Curilo, western Bulgaria, were treated by means of a constructed wetland located in the deposit. The waters had a pH in the range of about 2.5 - 4.1 and contained uranium, radium, some heavy metals (iron, manganese, copper, zinc, cadmium, cobalt, nickel, lead), arsenic and sulphates in concentrations much higher than the relevant permissible levels for waters intended for use in the agriculture and/or industry. The wetland covered an area of about 140 m2 and was characterized by an abundant water and emergent vegetation and a diverse microflora. Typha latifolia, Typha angustifolia and Phragmites australis were the prevalent plant species in the wetland but species of the genera Juncus, Eleocharis, Scirpus, Carex and Poa as well as different algae were also well present.The water treatment was started in July 2001 and until now (August 2002) the wetland effluents were characterized by pollutants concentrations decreased below the relevant permissible levels. The water flow rate through the wetland during this period varied in the range of about 0.2 - 1.0 l/s. The water clean-up markedly depended on the temperature but was efficient even in the cold winter months at air and water temperatures close to 0oC. The removal of pollutants was due to different processes but the microbial dissimilatory sulphate reduction and the sorption of pollutants on organic matter (viable and dead plant and microbial biomass) and clay minerals played the main role. Negative effects of the pollutants on the growth and activity of the indigenous plant and microbial communities were not observed."

Jan 1, 2003

By Carlos Collado, Oscar Jimenez, Francisco Diaz, Rodrigo Bernal, Carmen Salinas

Water is a strategic resource for the mining industry. The rising cost has forced the industry to become more efficient in their use, reduce and recycle waste as much as possible. The importance of having a reliable water balance is increasingly urgent, because the resource is scarce and vital to the sustainability of human life, animal and ecosystem. Conventional flowmeters can suffer disruptions or failures by corrosion, fouling, presence of elements in the water as acids, salts and suspended solids. Use of radiotracers is advantageous to determine fluid velocities that are transported through pipes, as they are detectable by means of the radiation emitted, the same way for surface flows, such as natural watercourses and drainage from tailings dams, fluorescent tracers are those with the best advantages. For velocity measurements in pipelines a Iodine-131 tracer solution, around 5 mCi was injected into the suction of the pumps. The technique used is the transit time between detectors at known distances and determining the time of passage of the radiotracer. For measurements of surface fluxes using the fluorescent tracer Rhodamine WT by tracer dilution technique, injecting the tracer at a constant rate and measuring it known concentration diluted downstream. This work has been performed in Minera Los Pelambres, located in the IV Region of Chile, measuring the flow rate pumped from 12 pools with 1-7 pumps operating, obtaining speeds of 0.56 to 2.62 m/s. In pumping wells three facilities have been measured at speeds of 0.111-0.223 m/s, plus six surface flows with flow rates of 8.45 to 357.2 L/s.

Jan 1, 2014

By Regis Texeira, Leopoldo Gutierrez, Vicente Hernandez, Caludia Vidal, Lina Uribe

"Molybdenum is currently the most important by-product of Chile´s copper mining industry. This mineral has gained international relevance over the years, because of its price. At mining deposits in Chile, copper and molybdenum are extracted together and then separated in a concentration process consisting of several flotation steps using sodium hydrosulfide (NaHS) as copper depressant. However, there are environmental issues related to the potential emisions of toxic hydrosulfide gas and bad odours, which affects nearby communities and suppose a risk for operators. This problem has led to the need for development of new technologies to eliminate the use of NaHS in the process of selective flotation of Cu and Mo minerals. In this work, results of flotation tests in which lignin derivatives reagents are used to obtain the selective separation of Cu and Mo minerals by flotation are presented. In this technology molybdenite is depressed by the action of lignin derivatives (lignosulfonates), while copper sulfides remain hydrophobic and float. The use of lignin derivatives in the selective flotation of copper molybdenum minerals represents a non-toxic alternative to NaHS.INTRODUCTIONSeparation of copper sulfides from molybdenite is commonly achieved through a two-stage flotation process. In the first stage the collective flotation of copper sulfides and molybdenite is promoted to generate a collective concentrate which is then treated in a second stage with sodium hydrosulfide (2.5-3.0 kg/t NaSH) to depress copper sulfides flotation without affecting the flotation of molybdenite. As a result a copper concentrate with 30-35% Cu, and a molybdenum concentrate with 50-52% Mo are generated. Although this process is widely used at industrial level, environmental issues related to the risk of H2S generation and bad odors have always been a concern. Thus there is a need in the industry for a more environmentally friendly process to separate copper sulfides and molybdenite."

Jan 1, 2018

By Kazutoshi Haga, Batnasan Altansukh, Shirchinnamjil Nyamdelger, Atsushi Shibayama, Narankhuu Ariunbolor, Gunchin Burmaa

In this study, the authors investigated the capability of an acidic thiourea solution and silicon-organic polymers (PSTM-3c, PSTM-3T) as ion-exchange resins to recover of gold from gold-bearing ore concentrates. Firstly, elemental gold present in flotation concentrates was dissolved by leaching with a solution of nitric acid and thiourea under the optimized conditions. The best result on gold thiourea leaching was obtained under a nitric acid concentration of 2 N, thiourea concentration of 2 %, and oxidant (Fe2(SO4)3) concentration of 3 %, solid:liquid ratio (S:L) of 1:20, leaching time of 6 hours at 20 °C with a gold recovery of 93.7 % for a gold flotation (unroasted) concentrate. For the roasted gold concentrate, the dissolution of gold was 94.8% under the optimized leaching condition as nitric acid concentration of 0.5 N, thiourea concentration of 2 %, and the oxidant concentration of 1 %, S:L ratio of 1:10, leaching time of 4 hours at 50 °C. Secondly, a series of sorption tests was carried out on a pregnant leach solution containing gold complex Au[S=C(NH2)2]2+ using silicon-organic polymers (PSTM-3c and PSTM-3T), respectively. The effects of solution pH, adsorption time and temperature in the sorption process are also studied. As the results, the PSTM-3c and PSTM-3T polymers were adsorbed about 94.4 % and 95.1 % gold from the pregnant leach solutions under the optimum sorption conditions, respectively. It was found that the both PSTM-3c and PSTM-3T polymers were effective for the recovery of gold from the pregnant leach solution of thiourea. Adsorption activity of the PSTM-3c and PSTM-3T polymers was confirmed by new peaks near 1700 cm-1 in the FT-IR spectrum of the gold-adsorbed polymers, respectively.

Jan 1, 2014

By J. Yvon, Inna V. Filippova

"The aim of this work is to seek the inhibitors of the meteoric and bacterial dissolution of sulphides and gangue minerals to stop the undesirable chemical reactions during conservation of the flotation wastes. The approach of passivation of surfaces by chemical treatment of the solid phase is applied for this objective.The samples taken from different depths of an old French waste dump revealed the capacity of the flotation tailings to produce acid waters (pH 1.8-2.4) and to release heavy metals. Mineralogical studies show not only the product of sulphide oxidation, i.e. sulphates, but also the complex transformations of aluminosilicates in acidic liquid phase. The detection by XRD of aluminium hydroxides (gibbsite, boehmite) allows supposing the recrystallisation phenomena during tailings conservation.Comparative tests of the passivation of the surface of sulphide minerals and waste of flotation with using of conventional reagents (CaO, NaOH, phosphates) and original reagents for this purpose (alkyl dithiocarbamates) allow to identify the optimal treatment conditions and the efficient chemicals.Leach tests were carried out in percolation columns during 68 weeks. The normalised leaching tests according to French legislation were run to confirm the selected treatment conditions. The results obtained show that a single treatment with carbamate inhibits the oxidation of the pyrite and the other sulphides, and totally prevents the formation of acid waters (the stabilised pH was 5.3-5.8). Treatment of in situ drainage water allows to obtaining a total precipitation of heavy metals: the residual concentrations of Fe, Cu and Zn are lower than 0,1 mg/l.The passivation of sulphides is the result of the formation with carbamate (studied by IR spectroscopy and XPS) of organometallic compounds, which are stable in acid medium. The presence of thiuramdisulphide (product of alkylcarbamate oxidation) at the mineral surface stabilises the mixed adsorption layer and leads to a considerable reduction in the hydratation rate of surface by avoiding the corrosion of the pyrite. No aluminium was detected in leach solution with this treatment."

Jan 1, 2003

By M. Özer, G. Önal, F. Arslan

"The use of ultrasonic in industrial processes has increased during the last few years. Ultrasonic vibrations are used in sieving, grinding, ore washing, cleaning, and flotation in mineral industry. There are also some attempts for the utilization of ultrasonic treatment in separation and removal of fine particles from gases and liquids. In Kalemaden A.S. (Turkey) four different types of clay mixtures (1. A mixture of clays from Balikesir-Düvertepe and Istanbul-Sile, 2. A mixture of clays from Ukrania and Balikesir-Düvertepe, 3. Sögüt-Kadikelimesi, 4. A mixture of clays from Sögüt and Istanbul-Sile) and kaolin from Balikesir-Düvertepe (Turkey) are concentrated before their use in ceramic production. Dewatering is the important step in those types of concentration plants. Sedimentation of concentrated clay has always been difficult and taken long times due to their nature and having small particle sizes. Flocculants can be used to enhance the sedimentation, but they are not preferred by the ceramic industry since they affect the quality of ceramic products. For this purpose, ultrasonic treatment is used in the sedimentation of clays mentioned above for solving the problems encountered related to the ceramic industry and promising results were obtained.Kaolin sample, subjected to this experimental study, from Balikesir-Düvertepe region of Turkey was brought from the plant as a pulp in containers and throughly mixed with a stirrer before sedimentation experiments. A two liter graduated cylinder and an ultrasonic bath (with 25 kHz frequency and 0.5 KW power) were utilized in the tests. Superfloc A-120 (1% concentration) was used as a flocculant. The settling distance was reported against the settling time during the experiments. Initial and final pulp densities were also determined. The effects of several parameters such as pulp density, flocculant addition, and ultrasonic treatment on the sedimentation of kaolin were investigated and the results are represented in terms of settling distance versus settling time."

Jan 1, 2003

By Áureo Del Vecchio, Lídia Dely Alves de Sousa, José Pereira

The potassium demand for agriculture purposes has increased in Brazil, which has great deficit of internal demands. Potassium-rich rocks have been used as fertilizers as technological alternatives for agriculture aimed to reduce the amount of chemicals and the sector dependence for such products. Vermiculite tailings from União Brasileira de Mineração - UBM, at Santa Luzia - PB, was studied aiming their application in agriculture by potassium release. The sample was analyzed by XRF and XRD; studies on release kinetic with particles smaller than 2 mm added of organic acids (citric and oxalic) at 10-2 mol/L concentration; samples were analyzed by XRD after kinetic assays. The work was conducted using a shaker incubator at 300-rpm agitation and time variation to better understand the potassium availability in the ground. Results show the presence of K2O at 3.46% concentration. Citric and oxalic acids increased the release speed to almost the same level with speed coefficients (k) of 2.61x10-2 h-1/2 and 2.55x10-2 h-1/2 respectively. In statistical terms for both acids, the linear equation represents more than 99.0% of the experimental assays. Stonemeal was applied to banana seedlings in experiment conducted in a greenhouse. The use of vermiculite tailings in banana seedlings promoted potassium absorption, which influenced its growth. The amount of potassium liberated from vermiculite tailings could be used as a long-term alternative to fertilizers in agriculture cultures.

Jan 1, 2014

By I. Zimbovski, T. Ivanova, E. Chanturiya

"The mechanism of selective action of new reagent-collector AMD of phenylpyrazolone class with sulphide minerals of copper-zinc ores was theoretically and experimentally investigated. The validation was carried out using spectrophotometry, Fourier-transformed spectroscopy, laser scanning microscopy, analytical scanning electronic microscopy and flotation. The reagent AMD in alkaline medium on chalcopyrite and sphalerite surfaces is chemically sorbed, forming strong hydrophobic complexes with copper and zinc. On the pyrite surface, AMD acidifies ferric iron ions with formation of hydrophilic oxidates. The selectivity of collector AMD with separation of sphalerite and pyrite in alkaline condition (??=10) is confirmed by flotation experiments. With AMD, the obtained recovery of sphalerite was 34.4 % at extraction of pyrite of 3 and 6 %. The low recovery of sphalerite is caused by weak collective ability of the reagent. The use of copper sulfate increases the flotability of sphalerite up to 82.0 % at extraction of pyrite of 5 and 2 %. It has been experimentally determined that during the flotation of sphalerite and pyrite by AMD reagent with addition of butyl potassium xanthate, and in the presence of copper sulfate and regulator of formation of ammonium thiocyanate complexes, the recovery of sphalerite is increased to 91 %, while the recovery of pyrite is decreased to 3.8 %. The chalcopyrite is floated actively (90 % recovery). The results of all theoretical research and experiments were confirmed by flotation tests on ores and products of dressing in industrial conditions."

Jan 1, 2014

By I. Blayda

The purpose of this work is to study and make comparative analysis of germanium extraction and related valuable components of the sublimates from the burning of domestic power coals (product 1) and germanium sulfide materials, which are a waste of lead-zinc production (product 2), by traditional chemical methods (distillation of germanium in the form of tetrachloride from raw and preliminary burning source) and by microbial bioleaching of sulfur-oxidizing bacteria. The dependence of the germanium extraction by chemical methods from phase composition of the initial raw materials was installed. The germanium tetrachloride extraction from products 1 and 2 were 78.50 and 19.52%, respectively. Such difference in indexes on extraction, is caused by germanium confinement as concomitant trace component to the basic phases to carriers. The share of acid-non-soluble compounds (tetragonal modification GeO2 and silikogermanaties) in the product 1 account for 21.5 % of germanium. Ratio between acid-soluble and acid-not -soluble germanium forms are 19.52 and 80.48 %, respectively, in the product 2. Our experiments have shown, that implementation of restorative firing (with addition of 30-40 % carbon at 1150 0?) of sulfide product 2 considerably impacted on the extraction of germanium tetrachloride (91.76 %) in comparison with its low enough extraction at straight distillation of hydrochloric acid (19.52 %). The results are confirmed by a set of physical methods. The results of processing the same so-called hard phase?s material (product 2) with the help of microorganisms are presented. It Has been established, that selected strains of bacteria are capable of extracting from initial raw materials not only macro components (iron, zinc, lead, manganese, aluminum, nickel), but also micro impurity of rare metals (gallium, germanium, zirconium). It is important that these metals were not extracted by traditional chemical methods (with application of aggressive conditions and heats) independently of the phase composition of the source. Almost complete extractions of germanium in solution using sulfur-oxidizing bacteria take place in the first day of the process independently of the phase composition of the source and the type strain. The results have practical significance and can be the basis for developing a unified biotechnological method of technogenic waste processing with a purpose of their sterilization and detoxification with simultaneous obtaining concentrates of valuable metals. Keywords: germanium, extraction, sublimates, bioleaching, sulfur-oxidizing bacteria.

Sep 1, 2012

By Andries Van Wyk, Steven Bradshaw, Guven Akdogan, Jacques Eksteen, Cornelius Snyders, Cleophace Mpinga

"In order to exploit lower grade and complex platinum group metal resources, cheaper and more efficient alternatives to the conventional mill-float-smelt-refine route are being sought, particularly for resources’ in areas that are water-scarce and where electrification is costly and problematic. Leaching with cyanide is a promising process option and although recoveries are lower than in the conventional process routes, progress into the understanding of cyanide leaching of PGM containing ore and concentrate has been made. Research regarding the feasibility of upgrading the pregnant PGM leach solution using activated carbon has, however, been lacking and hence forms the focus of this paper. Bottle roll adsorption tests for dilute PGM solutions (0.15ppm Pt, 0.38 ppm Pd, 0.1 ppm Au) onto granular activated carbon showed high rates within the first 60 minutes (giving more than 90% recovery of precious metals). Comparison of the Pt isotherm to Au isotherms from literature indicated a similar loading capacity, while that of Pd was found to be significantly lower. The effects of solution pH, temperature, base metal concentration, free cyanide concentration, thiocyanate concentration, initial PGM concentration and activated carbon concentration were investigated and are discussed. Elution of the Pt and Pd, with the AARL elution process, was found to be effective with recoveries of 95% after 5 bed volumes of eluant at the optimum pre-treatment concentrations and a temperature of 80°C. Temperature, NaCN and NaOH pre-treatment concentration and the ionic strength of the eluant were found to be the most important factors affecting elution while base metals concentration, acid-pre-treatment, carbon loading and thiocyanate concentrations to a lesser extent. Simplified combined flow sheets are suggested and the corresponding mass balances are compared."

Jan 1, 2014

It is well known that the crushing and grinding steps in the mineral processing of ores represent a substantial proportion of total energy, cost and carbon emission in mining. For instance a recent study calculated that 36% of the energy consumed by gold and copper producing mines in Australia was attributable to comminution (Ballantyne et al, 2012). Understanding this component of a business is essential in a world seeking to lower production costs, improve earnings and reduce its carbon footprint. The issue commands the attention and support of industry leaders in the mining sector, government, equipment manufacture, engineering design and research organizations. Furthermore, several researchers have often stated that globally, comminution processes consume between 3-4% of the world?s electrical energy production (Daniel and Lewis-Gray, 2011). In 2009-10, Australia?s Federal Government Energy Efficiency Opportunity (EEO) participants in the mining sector used 336.5 PJ, representing approximately 6 percent of Australia's total energy use. It is evident that the current practices of breaking rocks in tumbling mills are relatively inefficient (Fuerstenau and Abouzeid, 2002). Research and improved engineering design has established that a range of improved blasting, crushing and grinding techniques and flow sheets may lower project costs and carbon footprint. These include relatively simple process flow sheet strategies such as gangue rejection or pre-concentration prior to size reduction, a better combination of grinding technologies (both current and new systems), and selection of coarser grind sizes where ore and waste mineralogy allow. Yet, despite this systematic and detailed research, the industry remains somewhat reluctant to implement these strategies. CEEC (Coalition for Eco-Efficient Comminution) was established in 2011 to support knowledge sharing and change in an area of high-energy consumption for the global mineral industry. CEEC is a not-for-profit industry company, funded by grants from world wide industry companies, whose mission is to accelerate knowledge and technology transfer in the field of energy-efficient comminution. The key benefit to the mining sector arising from CEEC?s activities will be an increase in the rate at which more energy-efficient comminution data sets, processes, and technologies are developed, demonstrated, shared and applied. This will contribute directly to the industry?s target of reducing operating costs and carbon emissions. CEEC International Ltd and JKTech Pty Ltd teamed together to facilitate the inaugural CEEC Workshop, in June 2012. The purpose of the workshop was to produce a roadmap to provide guidelines for how (1) operations can achieve best EEC practice in the short to medium term, in collaboration with vendors, engineering companies and other service providers, and (2) what R&D is needed to achieve paradigm change in EEC in the medium to long term, e.g. 75% reduction in comminution energy in 10 years.

Sep 1, 2012