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By Liu Fan, Shang Yanbo, Wang Zhongming

"Besides valuable metals of Cu, Sn, WO3, Zn, there are S, Ag, CaF2, In and so on in a complex ore deposit in south China (which belongs to Hu Nan Shizhuyuan Non-ferrous Metal Limited Liability). Although it proved reserve amounts to 3.5×107 ton, its crystal character limits its utilization in large-scale. It features complex relationships between valuable minerals, finest crystallized particle size, low-graded valuable metals (Cu 0.30%, Zn 0.5-0.7%, Sn 0.2%, W<0.1%). If only tungsten minerals are considered, it means WO3 grade is too low (the cut-off grade of WO3 is 0.1% in China). Only Cu and Sn minerals are recovered from 2006 and Cu recovery is less than 70%, Sn 15-20%. Other valuable metals of W, Zn, S and CaF2 were lost in the tailings. To make good use of the ore, the technology of fully recovering Cu, Sn, W, Zn, CaF2 and rare metals are in urgent need. After systematic researches, the flow sheet of "bulk flotation of Cu-Zn minerals at first, then Cu-Zn separation, then recovering sulphide by flotation, then recovering iron minerals by magnetic separation, then bulk flotation of Sn-W minerals after desliming" is developed. Furthermore, specific Sn-W collectors of BK411 and BK412 are applied into the processes and better indexes are obtained. The industrial indexes are listed as followings: the content of Cu, Zn, Sn, WO3 of ROM ore is 0.31%, 0.65%, 0.13%, 0.03%; Cu and Zn recovery are 82.23% and 37.79% respectively; 63.76% of Sn and 34.34% of WO3 go into the Sn-W bulk concentrates. Economic benefits are remarkable."

Jan 1, 2014

By Gökçe Törenli, Okay Tutar

"Predicting the performance of plant-scale comminution circuits is essential to monitor the energy use and product size distribution, allowing us to control and optimize the whole process. In the light of this issue, with the assist of recent technologies, simulation techniques utilize the chance of putting the theory into practice in the most accurate way. For this purpose, this study aims to evaluate and optimize the efficiency of a plant-scale ball mill circuit by using perfect-mixing ball mill model on a simulation environment. The comminution circuit is selected from a specific copper-ore processing plant in Turkey. The essential parameters which are required for this study such as fresh feed Bond work index, size distribution etc. are determined by laboratory experiments. The forecasted data which are calculated by third-party software will be compared by the industrial operating data, in order to determine the performance of comminution circuit. In addition to that, this methodology provides a greater ability to analyse, optimize and understand the comminution circuit of ore treatment plant. The authors believe this work will provide supplementary data for further studies on simulation and subsequent optimization of comminution circuits.INTRODUCTION By the assist of mathematical models of the grinding mills and classifiers, simulation of the grinding circuits become more common in comminution because it is relatively economical and able to consider many variables simultaneously. It’s proceeds depends on the accuracy of the models and capability of reflect real operations. Computer-based simulation studies would provide the quantified information about the effects of the proposed changes on the comminution circuit performance in terms of size distribution, mass flow rates, equipment efficiency etc. Then the mentioned data used in order to check the suitability of the current equipment to the modified conditions, and for equipment selection. The outputs of circuit could also be used to estimate downstream flotation circuit performance because the general aim in this study is to The aim of the study is to investigate optimum operating variables and achieve p(80) size of 57 µm and 64 % of -36 µm particle in hydrocyclone overflow stream, which is optimum for that porphyritic copper ore for best concentrate recovery after flotation process in specific copper ore comminution circuit by using modelling and simulation techniques. Sampling survey was carried on the fine ore bin in order to perform Bond work index test and determine work index value (Wi). Thereafter mass balancing, using the size distribution data and tonnages, models for ball mills and hydrocyclone were developed. Finally, the circuit performance were investigated by computer simulations via JKSimMet software."

Jan 1, 2018

By Shibayama A.

In this research, an investigation of a process to selectively remove arsenic (As) and antimony (Sb) contained in enargite (Cu3AsS4) and tennantite/tetrahedrite ((Cu1,Fe)12(As,Sb)4S13) copper resources by leaching and precipitation were performed. First in the leaching process, the target was to selectively leach As/Sb and reduce their contents in the ores to <0.5 wt% followed by a second process to remove As/Sb dissolved in solution for environmental control. Enargite ore contained 3.65 wt% As while tennantite/tetrahedrite ore contained 5.40 wt% As and 4.85 wt% Sb. Alkaline leaching using NaHS?NaOH media at varying experimental conditions (temperature, pulp density, time, reagent concentrations) were performed to investigate the process. As/Sb precipitation studies were also performed to control high As/Sb concentrations in leach solutions by using elemental sulphur (So). Results from leaching studies showed that over 99% of As/Sb in the impure copper ores can be removed and their contents in the final solids reduced to <0.5 wt%. It was also established that such very high leaching could be achieved at 80°C within 1?6 h and pulp densities as high as 1000 g/L. The study also revealed that leach solution containing very high As/Sb concentration ranging from 5 to 20 g/L can be used as fresh solution for leaching of fresh ores until concentrations exceeding 35 g/L when it was sent to precipitation circuit for As/Sb removal. Addition of elemental sulphur at 90°C and fast cooling to 30°C allowed over 60% As/Sb precipitation and removed as Na3AsS4 and solution with reduced As/Sb concentration to leaching circuit for continuous use. Keywords: Enargite; Tennantite/Tetrahedrite; Selective Leaching; Precipitation; Sodium hydrosulfide;

Sep 1, 2012

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970?s, only the sub-aeration mechanical cells were dominant. Since the 1980?s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs.INTRODUCTIONFlotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. Froth flotation started in Australia at the beginning of the 20th century and since then flotation technology has made significant advances. Flotation was firstly applied to sulfide ores. The largest tonnages treated by flotation are copper and copper/molybdenum ores, handling about 50% of the total ore processed. Also significant are phosphate, iron ore and coal treatments. At present, Chile is the foremost copper producer in the world with around 35% of the world?s production. Figure 1(a) shows the evolution of copper production in Chile over the last decade. The total amount of fine copper produced in year 2001 was 4.7 million tons, from which 3.2 million tons was processed by flotation while 1.5 million tons went through LIX-SX-EW processes, which also showed significant development during the same period (Anon, 2001). The total flotation treatment of copper ores in Chile is about 325 million tons per year (Anon, 2002), so the world treatment of copper ore by flotation can be estimated at about 1 billion tons per year. Consequently a total of nearly 2 billion tons of ore per year is presently processed worldwide by flotation (Fuerstenau, 2001). In order to handle the higher tonnage of low-grade ore, a worldwide trend towards the development and use of larger flotation machines began in the 1960?s. Figure 1(b) shows that the trend became extremely marked from the beginning of the 1990?s, which is consistent with the strong increase in copper production during the same period."

Jan 1, 2003

Much has been published in recent years on the challenges facing the engineer of the 21st century and the consequent challenges facing the education providers and industry. The world is changing rapidly on the social, economic, political, technical and environmental fronts and our metallurgists/mineral processing engineers of the future will arguably need to have a different set of skills than those which were traditionally regarded as adequate during the latter half of the 20th century. This paper attempts to explore some of these issues and their ramifications.

Jan 1, 2014

By P. M. Solozhenkin, V. N. Kovalev

Russia is a global antimony market leader. The three major antimony production provinces are Sakha Republic (Yakutia), Krasnoyarsk Territory and Trans-Baikal Territory. Russia’s largest antimony resources are Zhipkozhinsky and Solonechensky deposits in Sakha Republic (Yakutia) and Olimpiadinskoe deposit in Krasnoyarsk Territory. This work demonstrates the efficiency of computer programs and chemical technology aimed at the study of the behavior of collectors used in the processes of flotation of antimony, arsenic and Au (I – III) minerals. The most promising collectors for the flotation of ores containing antimony and gold on the basis of P(V) and compounds with S, O and N atoms were chosen. The mechanisms of interaction with the mixtures of two or three components of collectors were studied. High recovery of antimony and gold was reached in the processing of Au-Sb ores of Sarulah and Sentachan deposits in Sakha (Yakutia). X-ray radiometric methods of separation of antimony ores of Trans-Baikal Territory deposits were proposed. In order to choose the most cost-effective solvents for hydrometallurgical processing of Sb, Au-containing concentrates the method based on clusters formation between transition solvents and antimony minerals was suggested. The nature of Au losses was theoretically revealed in the sulfide-alkaline process. On the base of computer simulation, the formation of various complexes of (KAu) types was developed, for example, hydrosulphidic gold, thiosulfates of gold - Na3AuS4O6, antimony and arsenic gold, trithiostibate (III) and trythioarsenate (III) KAu were produced. The practice of processing of goldantimony concentrates to produce high-quality antimony trioxide and antimony-gold containing alloy (AGCA) regarding the special conditions of the Far North region, were analyzed. The affinage of AGCA was recommended. Creative project development of antimony industry in Russia in order to produce antimony compounds and pigments, including pyriform compounds and flame retardants (antipyrenes) is discussed.

Jan 1, 2018

By Pan, Jian, Siwei Li, Deqing Zhu

"It is great significance to realize the efficiently and comprehensively utilization of iron, manganese and aluminum from refractory high-aluminum and high-manganese iron ores. Aimed at the two types of low grade refractory iron ores, mineralogical characteristics were studied. The direct reduction behaviors and evolution of mineral compositions of single iron ores and their blended ones were analyzed, and the corresponding reduction mechanisms were demonstrated. The results showed that only a part of iron oxides in high-aluminum ore are transformed to metallic iron after reduction, while the other react with aluminum and silica to form fayalite and hercynite which are difficult to be reduced. For the high manganese iron ore, most iron oxides can be reduced to metallic iron and manganese oxides can combined with aluminum-silica minerals to form galaxite and tephroite, promoting the reduction of iron oxides. Co-reduction results demonstrate that reduction of high- aluminum ore can be promoted by adding with high-manganese ore. Metallization and metallic iron grains increase dramatically by elevate high-manganese blending ratio. At the ratio of 60% high- manganese iron ore in the pellet feed, iron-slag separate well with a slag assaying 28.51%~36.35% Al2O3 and the recovery of iron and manganese can be reached 93%, respectively. The high-aluminum rich manganese residue was recycled with H2SO4. INTRODUCTION The growth of the Chinese iron and steel industry has been pushed forward by its rapid economic development in recent years, and 1126 million tons of iron ore have been consumed in 2014, where 933 million tons were imported according to the data from World Steel Association [1]. However, iron resources are limited, and especially the reserves of high-grade iron ores are declining, so it is of significant importance to optimize the mining rate of iron resources [2] and to utilize low- grade refractory iron resources, such as high-aluminum iron ore."

Jan 1, 2018

By William Skinner, Jonas Addai-Mensah, Keith Quast, David Robinson, Jason Connor

A review of the laboratory- and pilot plant-scale physical separation techniques for the beneficiation of nickel (Ni) laterites shows limited efficacy. To date, the only upgrade technique adopted commercially, prior to hydrometallurgical processing of Ni laterites, is the removal of a barren, coarse size fraction in the feed by classification. In the present work we investigated two low grade (~ 1%), goethite-rich Ni laterite ores’ upgrading by magnetic separation, attritioning/coarse, (lower Ni-grade) gangue rejection and flotation techniques. Low intensity (0.1T) dry magnetic separation at ambient temperature of raw samples and those pre-heated at temperatures up to 450 °C showed evidence of pay metal Co and Mn bearing asbolane and/or lithiophorite minerals pre-concentration in the magnetic fractions. Ni distribution, however, did not show any noticeable magnetic upgrade but followed the weight distribution. Other ore pre-treatment methods (e.g., desliming and sulphidisation) followed by froth flotation with anionic and cationic reagents also led to noticeable (~35%) Ni upgrade. This is due to the deportment of Ni across several gangue host mineral phases (i.e. Fe oxide/hydroxide and a range of silicate/aluminosilicate minerals). From chemical analysis, after disaggregation of ~ 1% Ni grade feed ore, coarse (-600 + 38 µm) and fine (-38 µm) fractions of ~0.6% and 1.3% Ni grades respectively, were also produced, suggesting that a significant upgrade in Ni content can be achieved by rejecting the + 38 µm fraction with the loss of <40% of the Ni. The ore mineralogy, particularly the complexity and high number of un-liberated Ni-bearing phases, greatly compromises physical separation methods for these ores, with the possible exception of screening after disaggregation of the fines inherent in the run of mine ores.

Jan 1, 2014

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 Yimin Zhu, Dezhou Wei, Haijun Liang, Zhifu Zhou

It has been fairly well established by many experiments that Thiobacillus ferrooxidans (T. ferrooxidans), also named Acidithiobacillus ferrooxidans(Kelly and Wood, 2000),can depress the floatability of pyrite. However, the mechanisms governing the process have not been known completely. In the present investigation, wettability and electrokinetic studies were carried out to examine the surface chemical changes on pyrite before and after interaction with T. ferrooxidans or its secretions. Attachment of T. ferrooxidans to pyrite was observed using a scanning electron microscope. The results of experiments showed that, under certain conditions, T. ferrooxidans and its secretions would obviously change the surface electricity of pyrite and result in the iso-electric point of pyrite shifting notably. However, the surface wettability of pyrite hardly changed and its hydrophobicity increased little after interaction with T. ferrooxidans and its secretions. Based on the results of the present investigation it can be reasoned that the depression of floatability of pyrite is due to the reduction of surface free energy, rather than the increase of surface hydrophilicity of pyrite. The decrease of surface free energy weakens the attachment of collector to pyrite; during the process bacterial protein plays the most important role and the bacterial chemotaxis strengthens the effect.

Jan 1, 2003

By V. A. Ivanova, T. N. Perunkova, N. O. Dorozhanova, G. V. Mitrofanova

"Oxyethylated compounds are used as reagents-regulators in the flotation of non-sulfide ores, in particular, apatite-containing ores. Thus, the necessary degree of selectivity in the flotation separation of two calcium-containing minerals of apatite and calcite is achieved only by using, in addition to a collector, regulators-reagents from the nonylphenol ethoxylates class. In order to establish the most optimal structures, this paper presents a comparative assessment of the physical-chemical and flotation properties of several classes of oxyethylated compounds - alkylphenol ethoxylates, aliphatic alcohol ethoxylates and oxyethylated carboxylic acid. The authors have studied their dispergating ability with respect to the air phase and calcium soaps of the carboxylic collector. Dependences of foaming properties of regulators on the degree of oxyethylation have been determined. Adsorption isotherms of sodium oleate on apatite and calcite in the presence of regulators have been obtained. It has been shown that the presence of oxyethylated compounds in the solution reduces the amount of the adsorbed fatty acid collector. The influence of the considered classes of regulators on apatite flotation has been studied. The interrelation of flotation properties of oxyethylated compounds and their molecular structure has been established.INTRODUCTION Flotation plays a leading role in complex apatite-containing ores processing. However, two calcium-containing minerals - apatite and calcite, which compose apatite-carbonate ores, are characterized by close flotation properties. Selective separation of these minerals is a difficult task, the solution of which is impossible without using reagents-regulators. One of the ways to ensure the selectivity of the flotation separation of calcium-containing minerals is the use of reagents-depressants such as sodium silicate, starch, cellulose derivatives, and others (Liu et al., 2016; Rao et al., 1989). Another method is the application of nonionic reagent regulators (Filippov et al., 2016; Filippova et al., 2014; Ignatkina, 2017), which contribute to the adsorption of the ion collector (Filippov and Filipova, 2006 Rao and Forssberg, 1997) and stability of formed froth (Sis and Chander, 2003)."

Jan 1, 2018

By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By Y. G. Seredkin, A. A. Vasiliev, A. Y. Senchenko, A. V. Aksenov

"The valuable materials resulting from the processing of gold-bearing ores are often refractory to direct gold recovery through cyanidation. There are multiple methods for chemical liberation of gold prior to cyanidation such as pressure and biological oxidation as well as atmospheric oxidation which is typically used in combination with physical activation of material by ultrafine grinding such as the Albion ProcessTM. This paper will examine the data from process testworks carried out to estimate the efficiency of the Albion Process™ for the oxidation of materials with a wide composition range prior to cyanidation. The data will be compared to that obtained by direct cyanidation of the feed (without oxidation) and from the testing of pressure oxidation on the feed prior to cyanidation. Albion Process™ tests were conducted in Institute TOMS with participation of Glencore Technology Pty Ltd (Australia). Refractory concentrates obtained from the ores of several Russian and CIS deposits were used as feed for the testing. These concentrates were also subjected to a material composition study and testing using conventional recovery methods. The resulted test data make it possible to perform an integrated assessment of process properties for materials with different compositions, compare performance of various process flowsheets for the materials under study, and conclude on efficiency of Albion Process™ application for gold recovery from refractory materials different in their composition.INTRODUCTION It is often the case that gold ore concentrates are refractory to gold recovery by direct cyanidation. This refractory nature is as a rule attributable to fine gold dissemination in minerals, most often in pyrite and other sulphides, as well as to the increased amount of components impeding cyanide leaching of gold due to cyanide consumption and reducing process conditions. The refractoriness of the concentrates results in low gold recovery values when conventional cyanidation technology is used. In this context, various additional processes are applied to breakdown such refractory sulphide concentrates, i.e. mechanical breakdown (fine and ultrafine grinding), chemical breakdown (atmospheric oxidation, e.g. Leachox, acid-oxygen oxidation, pressure oxidation – POX, bacterial oxidation – BIOX), and thermochemical breakdown (various roasting methods). Such breakdown processes allow for increase in recovery of finely disseminated gold during the downstream cyanidation, however, their application is cost-intensive and does not always ensure economic benefit."

Jan 1, 2018

By S. L. Gao

Based on the differences in hardness and density of diaspore and aluminosilicate minerals which usually exist in Chinese diasporic bauxite, It is analysed that bauxite of this kind is difficult to be separated effectively by classification and normal gravity separation, and cyclonic centrifugal field was thus proposed to be carried out, in which classification can take place according to the size difference resulted from selective grinding, what?s more, the separation function according to density difference is expected to take effect at the same time, and then cyclonic separation tests for diasporic bauxite of A/S 4.39 and grinding 61.90% -0.074mm were carried out tentatively. The results showed that the accretion of feed pressure can offer strong enough centrifugal force for cyclonic separation with result that separation function according to density difference is effectively intensified, by the increasing of this parameter, underflow and overflow of A/S 7.64 and 2.18 can be processed at the same time, and the recovery of Al2O3 in underflow is 71.78%; judging by the flow ratio, the spatial locality envelope of zero vertical velocity do constringe to the vertical axis by the enlarging of diameter ratio of apex to vortex, overflow and underflow of A/S 2.08 and 6.5~7.0 can be processed by controlling this structural parameter, which is possible to offer a technological method for low-grade bauxite to de-sliming beforehand.

Jan 1, 2014

By Yuhua Wang, Huilan Yang, Yanqing Jiang, Dongfang Lu

"Generally, the concentration of bauxite flotation tailings is around 10%, a large amount of water in tailings needed to be recycled in the flotation process. Sedimentation and dewatering properties of tailings were investigated under different conditions. Surface high negative charges on mineral particles are the key factor to destroy the settlement of tailings when the pulp pH is around 8.9. Hence, the modification of pulp pH around 7 is necessary to the diminution of the repulsive force between mineral particles and then the acceleration of sedimentation of tailings. Anionic polyacrylamine with molecular weight of 14 million is the best flocculant for the settlement of tailings in all tested polyacrylamines. P-toluene sulfonic acid shows better properties than hydrochloric acid for pulp pH adjustment when anionic polyacrylamine with molecular weight of 14 million is used as flocculant. Although the flotation of diaspore is depressed in the presence of polyacrylamine using sodium oleate as collector, but the recycling water traded by the combination of ployacrylamine and p-touenesulfonic acid does not show the depression effects on the flotation of bauxite ore. The lower residual content of polyacrylamine in recycling water treated by the combination of ployacrylamine and p-touene sulfonic acid plays an important role. INTRODUCTION Generally, the waste water generated from mineral processing plant is usually treated by sedimentation, oxidization, electrodialysis, ions exchange, active carbon adsorption and flotation technology, and the treated water is also used again in the industrial process. Flotation was adopted widely to improve the quality of bauxite from low grade diasporic bauxite in China. For flotation, the grinding fineness of bauxite is over 90% -0.074 mm, sodium carbonate and sodium hexametaphosphate were used as regulators, so the tailings pulp is very difficult to settle and be dewatered (Y. Wang et al., 2004; Y. H. Wang et al., 2007; Wang Yu-hua et al., 2008; Wang Yuhua et al., 2011). The water recycling of bauxite tailings are becoming the highlight for the industrial application of the flotation process for bauxite ore. Researchers in China shift their attentions onto this topic."

Jan 1, 2018

By A. Akcil, O. Celep, C. Erust, E. Y. Yazici1, H. Deveci1

"Recycling of WEEE has already gain prime importance from both environmental and economic point of view. For the recovery of metals from e-waste, many conventional physical, bio/hydrometallurgical and pyrometallurgical processes are proposed. Economic potential of e-waste is mainly driven by its precious metal content. Physical separation methods (e.g. electrostatic, magnetic, eddy current and gravity separation) exploit the differences in the physical properties of metals and non-metals. Physical separation methods are simple and economically sound but they suffer from metal losses and ineffectiveness at fine sizes. Hydrometallurgical processes are promising owing to their relatively low cost, reduced environmental impact, potential for high metal recoveries and suitability for small scale applications. Hydrometallurgical processes can be developed for selective extraction of base/precious metals using suitable reagent systems. Sulphate-based leaching with a suitable oxidant (e.g. H2O2, O2, Fe3+) is effective for copper and other base metals. After removal/recovery of base metals, precious metals can be easily extracted using various lixiviants including thiosulphate, thiourea, cyanide and chloride. However, further research is required to develop new, cost effective and environmentally friendly processes and/or refine existing ones for leaching and, in particular, downstream processes. INTRODUCTION Electrical and electronic equipments are indispensable to modern societies with numerous applications in the field of medicine, transport, communication, education, security and environmental protection. With technological developments and innovations, the replacement of old equipment leads to ever fast accumulation of waste materials such as waste electrical and electronic equipment (WEEE or e-waste). People are upgrading their mobile phones, computers, televisions, audio equipment and printers more frequently than ever before (Babu et al., 2007; Lee et al., 2007). With the rapid growth in technology today, the life span and utilisation period of most electronic and electrical equipment has been reduced considerably with concomitant generation of huge amounts of WEEE over the past several decades. According to statistics presented by Balde et al. (2015), total WEEE produced around the world was 41.8 million tonnes in 2014 and expected to rise to approximately 50 million tonnes by 2018. Kumar et al. (2017) estimated that annual growth rate for the WEEE stream is 3–5% (Singh et al., 2016). The aim of this paper is to provide an overview of physical separation and hydrometallurgical methods available for the treatment of WEEE."

Jan 1, 2018

By A. L. Hinde

The steady-state and dynamic behaviour of semi-autogenous grinding (SAG) mills are arguably best described using a population model that caters for the breakage kinetics and the material trans-port of rock and pulp inside the mill. Breakage kinetics are usually expressed in terms of a specific breakage rate function and a separate primary breakage distribution function. Material transport usually invokes the concept of a specific discharge rate function. Unfortunately, the breakage rate and breakage distribution functions for SAG mills are very difficult to estimate uniquely from plant data alone. Simplifying assumptions must be made to over-come this problem, which leads to many unresolved dilemmas with regard to whether or not the de-rived functions are accurate, precise, and reflect reality. For example, it is sometimes assumed that the breakage distribution function for a SAG mill treating run-of-mine ore can be derived from laboratory dropweight and tumbling tests on small rocks in narrow size ranges. Such tests hardly reflect the environmental conditions likely to be encountered in a pilot or production SAG mill where there is a wide spectrum of particle sizes. It is shown that the dilemmas associated with standard population balance models (models that utilise separate breakage rate and breakage distribution functions) can be overcome by expressing breakage behaviour inside a SAG mill in terms of a single function. This function is an energy-based cumulative breakage rate function defined as the fractional rate at which particles and rocks coarser than a given size break to below that size per unit specific energy input. A model for SAG milling is formulated, which invokes the concept of a cumulative breakage rate function. Comparisons are made between the mathematical structure of this ?simple model? and standard population balance models. Perhaps the most attractive feature of the ?simple model? is that the cumulative breakage rate function can be uniquely estimated from measurements of size distributions and mass flows of the feed and discharge streams together with the size distribution and holdup mass of the mill charge. Such measurement can easily be made at pilot scale. It is concluded that this simplified approach to SAG milling may turn out to be the quickest way to fully describe and quantify the performance of these very complex mills.

Jan 1, 2014

By Ata Akcil, Z. B. Karshigina, Ye. G. Bochevskaya, E. A. Sargelova, Z. S. Abisheva

Phosphorus slag is one of the most large-tonnage of yellow phosphorus production waste, which for decades stored in the slag disposal, by polluting the environment and creating environmental problems in the regions. Phosphorus slags from the processing of Karatau phosphorites are a very promising source of raw materials not only for silicon compounds but also rare earth metals (REM). Among the REM, yttrium, neodymium, europium and lutetium predominate, which are relevant to high-tech industries. The report presents technological scheme of complex processing of slags of phosphoric production with obtaining of REM concentrate and precipitated silicon dioxide ("white soot"). The regime parameters of the main operations of the technology are determined: I stage- leaching of slag with nitric acid solution; extraction of the REM-containing solution with tributyl phosphate and stripping of the REM with water; settling of solution of salts of oxalic acid, calcining the precipitate to obtain a concentrate S REM oxides and II stage of leaching silicon cake to obtain "white soot". Recovery of S REM from slags of phosphoric production on various redistribution has made, %: leaching – 95.0; extraction - 90.2; extraction on the average ~ 93.2; the production of a concentrate of REM oxide is 93.9. A concentrate containing 17.3 % of REM oxides was obtained. According to X-ray analysis it contains the following phases: calcium oxide, portlandite2, gadolinium oxide and yttrium, gadolinium oxide, gadolinium oxide and cerium, neodymium oxide, neodymium oxide and cerium. Thus, the concentrate can serve as a raw material for the production of individual rare-earth metals like gadolinium, cerium, yttrium and neodymium. After performing the II stage of leaching siliceous cake with nitric acid the samples of "white soot" were obtained. Its chemical composition corresponds to the state standard and has a specific surface area equal to 180 - 200 m2/g. The technology has been tested in a large-scale laboratory scale and will solve the problem of complex processing of phosphorus raw materials and import substitution in Kazakhstan. The end-to-end recovery of S REM oxides and silicon into concentrate and product from their initial content in slags is ~ 75.0 and 98.0 %, respectively.

Jan 1, 2018

By Larry A. Cramer

"Three primary drivers are setting the trend for base and precious metal processing . they are: continued low real base metal prices, environmental concerns, and continued high prices for PGM.s. Low base metal prices are increasing the search for economies of scale and company consolidation as well as the development of some hydrometallurgical technologies. Environmental concerns are pushing for continued reductions in SO2 emissions and hydrometallurgical technologies. The high prices for PGM.s are driving major expansions and a focus on minerals processing recoveries and, to a lesser extent, reductions in the refining metal lockup.In nickel, HPAL operations on laterites have failed economically but Inco is still pursuing some alternatives. BHP-Billiton and others are developing bioleaching alternatives for nickel laterites and sulphides.Copper continues to be dominated by the hydrometallurgical and pyrometallurgical debate; new hydrometallurgical developments are being tested at several sites whilst the pyrometallurgists continue to make competitive cost and environmental improvements.Gold processing developments are dominated by the use of improved gravity recovery equipment and by the development of thiosulphate as a more environmentally acceptable lixiviant.PGM processing trends are the use of fine grinding technologies, higher power input flotation cells, and new pyrometallurgical technologies. Hydrometallurgical options for some applications are being sought.OVERVIEW The metals industry has remained under price pressure for some time; low and decreasing real prices for most metals have become an expected scenario. Occasional price spikes give some relief but invariably bring expansions and new entrants into an already oversupplied commodity market, thus leading to the continued price pressure. Technical innovation, economies of scale, and improved work systems are continually sought, so as to improve the competitive position of each individual company in such a climate; however, these developments add to the downward price pressure. In such a situation the application of scarce funds to research and development is a difficult task. Excess funding is not available in tight economic times and yet the main route to higher profits is clearly the application of technical developments to lower the cost of producing a metal commodity. Many technical centers have closed as a cost saving exercise and some have coalesced to obtain economies of scale. The Australian based AMIRA research organisation has grown to serve the R&D part of the market well in Australia and in South Africa by acting as the catalyst to form research partnerships between a number of industry players and as an administrator to direct the funding of research projects towards the various applicable research institutions. AMIRA has developed closer ties to Camiro (Canadian Mining Research Organisation) through the appointment of Camiro.s metallurgical processing research director as AMIRA.s North American based director. AMIRA is continuing discussions with MIRO (Minerals Industry Research Organisation) in regard to a merger, with a report outlining the merger proposal expected in March of 2003. Company focused research centers continue to be effective at Anglo American Research Labs, Teck-Cominco Research, Falconbridge Research center, Inco Research and some others."

Jan 1, 2003

By Hajime Miki, Gde Pandhe Wisnu Suyantara, Tsuyoshi Hirajima, Keiko Sasaki

"Hydrogen peroxide (H2O2) is frequently used as an oxidizing agent in various applications. It has also been reported to reduce the recovery of sulfide minerals. Moreover, the previous work applied H2O2 aqueous solution in selective flotation of chalcopyrite and molybdenite. However, the oxidation method suffered in pilot scale test due to too long conditioning time. Furthermore, the excessive reagent consumption increased the reagent cost, causing the method not economically feasible. Consequently, further improvement is required to reduce the conditioning time and the reagent consumption. The oxidation performance of H2O2 can be improved by using ferrous iron as catalyst, producing a Fenton’s reagent which is more powerful oxidizer than the H2O2 itself. Therefore, the effect of Fenton’s reagent on the floatability of chalcopyrite and molybdenite was investigated in this study. The flotation test results show that selective flotation of chalcopyrite and molybdenite might be possible at low concentration of H2O2 aqueous solution by adding ferrous iron. Moreover, the conditioning time could be shortened by this improvement. To understand the phenomenon, surface characterization using atomic force microscopy (AFM) along with x-ray photoelectron spectroscopy (XPS) analysis were carried out. The AFM images show that the surface of chalcopyrite was readily covered with mountainous features which alters its hydrophobicity after the oxidation treatment. Meanwhile, the molybdenite surface remained clean and relatively hydrophobic. The XPS results indicate that the mountainous features are various oxidation products (i.e., FeOOH, Fe2(SO4)3, CuO, Cu(OH)2). Possible mechanisms of this phenomenon were proposed in this work.INTRODUCTIONConventionally, copper and molybdenum ores are separated in selective flotation circuits by using copper depressants (i.e., sodium hydrosulfide (NaHS), sodium sulfide (Na2S), and Nokes reagent (P2S5+NaOH)). However, these depressants are usually toxic or hazardous. Therefore, various methods have been developed to replace these toxic and hazardous depressants, for example, by synthesizing new non-toxic or low-toxic depressants or by using various oxidation methods such as sodium hypochlorite in an alkaline medium, manganese dioxide, oxygen, ozone, and plasma pre-treatment (Arbiter and Young 1951; Barzyk et al. 1981; Curtis 1941; Hirajima et al. 2014, 2017). Recent study by Chimonyo et al. (2016) reported the effect of H2O2 on reducing the recoveries of sulfide minerals. Moreover, Hirajima et al. (2017) demonstrated that H2O2 depressed the floatability of chalcopyrite and could deliver a selective separation on copper and molybdenum (Cu-Mo) bulk concentrate in flotation process. However, they reported that this method required a higher concentration of H2O2 and a longer treatment time (4.5 h) to get a comparable result to that of using NaHS as copper depressant. Therefore, further improvements are necessary to reduce the conditioning time and reagent consumption."

Jan 1, 2018