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By Benoit Clermont, Jan Lux

"Magotteaux and Anglo Platinum started a co-operation program with the main aim of establishing the optimum milling configuration measured in terms of throughput, fineness and energy consumption.For this purpose, a fully instrumented pilot milling plant, supplied by Magotteaux (Pty) Ltd, and equipped with a 0.9 x 1.0 m ball mill, was erected at Frank concentrator (Merensky Pt ore). The primary ball mills at Frank concentrator were surveyed in order to set the conditions for the base case. This data was then replicated in the pilot mill under the same configuration. Thereafter, a series of different parameters were varied in order to attempt to optimize the milling system.Some of the grinding parameters that have been studied are:•,Gate versus overflow discharge•,Open versus closed circuit•,Different filling degrees•,Different shell liner profilesOnly grate versus overflow discharge and open versus closed circuit will be discussed in this paper.It should be noted that this paper does not attempt to give a universal solution as to what milling configuration is optimum in all cases. The conclusions apply for this particular case and probably most others, but it would be advisable to consider each case on its own."

Jan 1, 2003

By M. A. Naimanbayev, Zh. A. Baltabekova, N. G. Lokhova

"Integrated utilization of natural resources using energy-saving and waste-free technologies is relevant around the world. This applies to such type of raw material as titanium-magnetite ore. Shortage of ilmenite raw materials in the Republic of Kazakhstan for titanium slag melting challenges the search of alternative titanium-containing raw materials, titanomagnetites in particular. At the same time there are deposits of indigenous titanomagnetite ores of huge reserves, which can become the complex raw material for production of iron, titanium and vanadium. Tymlay field in the South-Eastern part of Chu-Ili watershed is of particular interest, within the Karasay ore unit with iron content of 30,4 and titanium dioxide - 10%, and after beneficiation titano-magnetite concentrate contains Fe-52,4; TiO2-of 16,06%. Technology of titanium-magnetite concentrate ore-thermal melting was developed at Tymlay deposit producing hot metal and low titanium slag that can become the raw material for titanium production using chloride method. Slag produced in course of titanomagnetite ore-smelting consists mainly of alumosilicates and sodium silico titanates, magnesium and calcium titanates, titanium dioxide and lower titanium oxides. Following operations were carried out to improve titanium slag quality: slag sintering with sodium hydroxide; cake leaching with water to remove water-soluble impurities; to reduce the number of operations impurities leaching with hydrochloric acid was combined with pyrohydrolysis of titanic acid; rutile concentrate production (85% TiO2, 7,66% SiO2), silica removal by means of sodium hydroxide solution treatment, finally sellable rutile concentrate was produced with titanium dioxide 91-92% and silica 1,7 to 2,0% content. Based on research results technological scheme of titano-magnetite concentrate processing at Tymlay deposit was proposed producing hot metal and certified rutile concentrate, suitable for chlorination."

Jan 1, 2018

By A. S. Chekmarev, T. Z. Lygina, K. G. Egorova, A. V. Skvorcov

"We have conducted analytical and technological evaluation of sepiolite containing clay. The possible areas of application of the sepiolite have been investigated and complex methods of enrichment of natural sepiolite have been identified. It was determined that for preserving the structure of minerals after processing the most effective method of the natural agglomerates disintegration was the soft abrasion of the clay fraction up to 0,5 mm. Disintegration of sepiolite clay along with using high energy-stressed effects on the matrix can deteriorate the rheological properties of clay suspensions and reduce the yield of drilling mud and sorption properties. To improve the quality of clay powders we used combined gravity-modifying method of wet enrichment. After the wet enrichment the yield of drilling mud increased up to 12.7 m3/t, with the addition of MgO up to 20,3 m3/t. It was noted that drilling muds contenting more than 50% of sepiolite are stable in mineralized (salt) waters. Based on the studied activated sepiolite rocks we obtained the effective heat-insulating materials with relatively low thermal conductivity – 0,165 W/m·K, average strength – 7,29 MPa and water absorption-49,0%.INTRODUCTION The modern development of the Russian economy requires the implementation of scientific and technical tasks. The solutions of it involves a radical reduction in energy, heat losses and material consumption of products, rational and efficient using of all types of resources, as well as the using of new types of mineral raw materials and materials based on it. An example of a new type of mineral raw materials for Russia is sepiolite containing rocks, due to unconventional conditions for their soils accumulation in the climate of the Far North. Sepiolite is a unique type of nonmetallic mineral. It is formed in soils, marine and saline basins, occurs in carbonate and carbonate-clay rocks in the form of lenses and lens – shaped layers, rarely nodules, loose powdery masses, shell-like concretions. Sepiolite may have a soft porous macroscopic appearance or less often the structure of the fibrous mass. Color of sepiolite is from white to cream with gray, green, pink and even crimson shade depending on the degree of pollution. Sepiolite can be in two forms - a-sepiolite (parasepiolite), which occurs in the form of large packets of crystalline fibers and ß-sepiolite, which occurs in the form of amorphous aggregates or small flat rounded particles. The sepiolite fibers have a length of from 0.2 to 2 Å, width from 100 to 300 Å, the thickness from 50 to 100 Å (Geological dictionary, 1973)."

Jan 1, 2018

By K. Kiangi

On installing the Metso Superior MK 54x75? primary gyratory crusher in Nkomati mine the crusher experienced severe power spikes greater than 1000kW which subsequently led to the crusher tripping under load while processing some of Nkomati?s MMZ ores. Likewise significant losses in throughput were also experienced while processing some of Nkomati?s MMZ ore types. Interestingly the crusher was capable of processing the PCMZ ores without experiencing any power spikes or losses in throughput. Investigations into the challenges faced by the crusher while processing Nkomati?s MMZ ores were conducted using the DEM model in conjunction with the fast breakage model present in Metso?s High Fidelity Simulator. The intentions of the study were to establish the most suitable operating conditions or cavity design that would potentially enhance the performance of the crusher. Likewise an understanding of the effects the feed conditions (size distribution and hardness) had on the crusher?s performance was established. Ore characterization tests were conducted on Nkomati?sPyroxenite, Diabase, Calc silicate and quartzite ores which were from Nkomati?s MMZ ore body. The ore characterization tests conducted were drop weight tests, slow compression tests and elastic modulus tests. Four simulations were conducted used the existing cavity design with various open side settings (OSS) and throws. This established the effects of changing the crusher?s operating conditions on its performance. Four additional simulations were conducted on two cavity designs with reduced volumes. This established the effects of changing the crusher?s cavity design on the crusher?s performance. Thus through the simulations a better understandings of the impact of the crusher design, operating conditions and feed conditions on the crushers performance. Furthermore an analysis of the crusher?s performance was made which was used as a basis for comparisons with the base case simulation. Keywords: crusher, discrete element method, simulation, ore characterization

Sep 1, 2012

By L. X. Zeng

The low-grade nickel resource is very abundant in the western China. To make the best of the low grade nickel ore, we studied the process mineralogy and beneficiation process of nickel ore in the Yangliuping of Sichuan province. The grade of nickel is 0.45% in the nickel ore and the nickel exists in the sulfide including pyrrhotite, nickel pyrite, chalcopyrite primarily. The nickel distributes in pentlandite and magnetite over 90% and the copper does in the chalcopyrite over 95%. The carri-er minerals of useful elements tend to concentrate in space for concentration. As is shown in grain-size analysis of three major minerals, there are some more fine-grained grains with the percent of from 10% to 15% (<40 µm) and from 3.5% to 5.5% (<20 µm). So there will be some smaller size disseminated sulfide minerals difficulty to liberate in the process of concentration. The liberation degree of sulfide is not high and there are much associativity in the sulfides. Therefore, we should reclaim the sulfide aggregation dominating as pentlandite when concentrating. In addition, the sulphide minerals is so brittle that we should take care of preventing from crashing when grinding. The gangue mineral is mostly metamorphic mineral including serpentine, chlorite and amphibole which is easy to be argillization and difficult to concentrate.

Jan 1, 2014

By Peng Qian, Xiao Li, Guoyan Fu, Peiwei Han, Yongliang Wang, Shufeng Ye

"Arsenic removal from high arsenic gold concentrate is conducive to increase the mineral value and realize the mineral comprehensive utilization. This study investigated the alkaline pressure oxidation leaching (APOL) of an arsenical gold concentrate in lower temperature to separate the arsenic into filtrate. The effects of temperature, NaOH concentration, solid-liquid ratio, reaction pressure and stirring speed on the leaching efficiency were investigated, and the characteristics of the gold concentrate and leaching residues were evaluated using XRD and SEM analysis methods. The obtained results showed that by using lower temperature (<60?) it is possible to avoid the production of elemental sulfur during the leaching process, which is benefit for the oxidation of arsenopyrite; When the reaction was carried out under appropriate conditions, more than 98% of the arsenic will be extracted into the filtrate as the form of arsenate or thioarsenate. INTRODUCTION In recent years, there has been considerable interest in the recovery of gold from refractory arsenical gold ore. The arsenic in this kind of ore usually exists as the form of arsenopyrite, and the gold surrounded by arsenopyrite exists as the form of fine particles, which will give many difficulties to metallurgical work. When the content of arsenic in the gold ore is more than 0.5%, it will seriously penalize the smelting efficiency (Ruiz et al., 2014). So pretreatment of the refractory gold ore is necessary to obtain the largest economic value and environmental benefits (Balaz et al., 2000). The oxidation pretreatment processes mainly include roasting oxidation, pressure oxidation, chemical treatment and biological treatment (Ann et al., 1992; Kou and Chen, 2012; Tongamp et al., 2010; Fernandez et al., 1995; Lin and Zheng, 1996). Among them, the roasting oxidation and pressure oxidation are the more ordinary processes in industry. The roasting oxidation process is the mature and adaptable technology, but the production of waste gas containing sulfur and arsenic will pollute the environment. The pressure oxidation method possesses certain metallurgical and environmental advantages, and can efficiently decompose the mineral. According to the different solution media, the pretreatment can be divided into alkaline and acidic pressure leaching pretreatments (Papangelakis and Demopoulos, 1990; Hiskey and Sanchez, 1995). The acidic pressure oxidation method has been used in most smelting plants for high arsenic gold ore pretreatment, while the alkaline pressure oxidation is still not widely applied. Compared with the acidic pressure oxidation, the alkaline pressure oxidation can be realized under lower temperatures."

Jan 1, 2018

By Chuanyao Sun, Zhenguo Song, Aijun Ren

"Lead-Zinc sulfide ore containing carbon is one of typical refractory resource. Because organic carbon has natural floatability, it has a great negative influence on flotation of lead-zinc sulfide ores. It is difficult to obtain qualified lead concentrate by flotation using conventional reagent system. In order to reduce the influence of organic carbon on lead and zinc flotation, two alternatives, i.e., removal carbon by pre-flotation or adding carbon depressant in lead and zinc flotation, can be adopted. If the flowsheet of removal carbon by pre-flotation is adopted, the lead and zinc recovery which are lost in the carbon tailings is often higher. If conventional carbon depressants are used in lead and zinc flotation, it has a certain depression effect on lead minerals. In the paper, the ore grading 1.49% Pb, 5.73% Zn, and organic carbon 3.14% has been carried out by flotation tests. In the bulk flotation of carbon and lead minerals, Pb concentrate is only about grading 21.00% Pb. In the pre-flotation of organic carbon, it’s hard to remove most of carbon, and the loss of Pb and Zinc recovery is too much in carbon tailings. New carbon depressant BK547 and three conventional carbon depressants including sodium lignosulphonate, Fe-Cr-lignosulfonate, and dextrin, are used in comparative tests of Pb flotation, and results show that BK547 have a good depression on organic carbon, and have almost no effect on Pb flotation. Using BK547 as carbon depressant, cycle test in flowsheet of two-stage Pb and Zn selective flotation and coarse concentrate regrinding have been carried out, and results show that concentrates grading 62.51% Pb and 41.33% Zn are obtained at recoveries of 70.24% Zn and 83.58% Zn.INTRODUCTION Lead and zinc mineral resources are still the main source of lead and zinc metal. For lead-zinc sulphide ore, lead concentrate and zinc concentrate are obtained by flotation. Minerals separation by flotation is a complex process and is dependent, along with other factors, on the relative distribution of hydrophobic (e.g. collector, polysulfide, elemental sulfide) and hydrophilic (e.g. metal hydroxide) species between different particles of the same mineral phase and between mineral phases (Piantadosi & Smart, 2002; Boulton, Fornasiero & Ralston, 2003). Organic carbon has natural floatability and is often associated with lead-zinc sulphide ores. If the content of organic carbon in the ore is more, the flotation index will become worse. The main problem is that the concentrates has too low grade to be qualified grade products for sale. At the same time, the consumption of reagents is more than ordinary ores without organic carbon. In order to solve the influence of organic carbon on the flotation of lead and zinc and other sulphide ores, a lot of research works have been carried out."

Jan 1, 2018

By A. V. Yevdokimov, Ye. V. Bogorodsky

The paper presents the results of the research on the development of gravity concentrates processing technology (gold grade is from 50 g/t to 1 kg/t and over) using intensive cyanidation with gold recovery to pregnant solutions followed by precipitation of metals from them using various methods. Test work and pilot plant results confirm that a new developed hydrodynamic regime provides an efficient treatment of gravity concentrates of polydisperse composition without their grinding and preliminary desliming. The resulting pregnant and washing solutions are amenable to metals recovery using electrowinning, cementation onto zinc dust and CIS. Cone plants with a lower ball valve for cyanidation of unground gravity concentrates developed by IRGIREDMET JSC have been successfully tested at a number of Russian operations. Currently, a modular plant equipped with gold electric precipitation from pregnant solution unit is successfully operated at a Russian gold processing plant. Cyanidation of the resulting high-grade gravity concentrate is carried out at the concentration of 8-10 g/L NaCN and 10 g/L NaOH. Gold recovery to the solution is 97-98%. Electrowinning is carried out in flow cell GNC-40M. In this case, the residual gold concentration yield is 0.3-0.5 mg/L. Also, a modular plant for relatively low-grade middlings (50-100 g/t Au) of gravity concentration has been introduced. The concentration of NaCN and NaOH is 2-3 g/L and 1.5-2 g/L, respectively, during leaching. This plant is equipped with a unit for gold cementation from pregnant solution with zinc dust. This cementation unit is of original design. It is made in the form of a filtering device and is composed of several layers of carbon fiber which contacts with zinc powder. The residual gold concentration yield from a cementation unit is less than 0.1 mg/L. Gold recovery is 93-97%. In 2017-2018, the introduction of intensive cyanidation modular plants to gravity concentrates will be planned at new projects of Russia and the CIS.

Jan 1, 2018

By Caibin Wu, Ali Lei, Ningning Liao, Jingsheng Ye

"The particle size distribution characteristics of ground product can influence the quality of the classification overflow and the next beneficiation indexes in an ore concentrator. Usually, the size distribution of ground product is considered to be determined by that of new ball mill feed. However, based on large amounts of data from industrial grinding circuit surveys, this paper has clearly shown that the size distribution of ground product should be determined by the size characteristics from classification underflow unless the circulating load was small, because the new feed is an important component and occupy a dominant position of mixed ore from belt feed and classification underflow. On the other hand, the correlation coefficient of the size distribution between ground product and classification underflow can be more than 0.99 when the relevance principle and its method are used. Meanwhile, their P80 value also keeps a synchronous correlation. The greater the capacity of classification underflow is, the higher the correlation of size distribution between the ground product and the mixed feed is. Furthermore, the correlation coefficient of the size distribution between ground product and classification overflow which is from primary or secondary can be 0.96. It is another discovery that the correlation coefficient is related to the type of classifier. The coefficient of size distribution of overflow and underflow from hydrocyclone is superior to that of spiral classifier, which can explain the reason why the hydrocyclone is widely used to replace the spiral classifier in concentrator.INTRODUCTION It is well knows that ball mill circuits closed with cyclones or spiral classifier such as a primary grinding circuit, a secondary grinding circuit and SAB mill have become an industry standard. Which grinding process employed will be determined by the P80 value of ground products. When the primary closed circuit ball mill or SAB that it is different throughout between the two processes was employed, a grinding fineness with -200mesh under 68% will be available. However, the secondary grinding circuit with the fineness of -200mesh above 80% can be conducted. Of course, the grinding fineness is determined by the grain size characteristics of the mineral."

Jan 1, 2018

By S. Cagirici, Z. Öztürk, A. Hassanzadeh

Many flotation kinetics models have been studied in the literature. Their applicability was extensively investigated and argued in detail. However, model selection criteria were not adequately discussed from the statistical points of view. In this investigation, the kinetic behavior of a complex copper sulfide ore was studied in a mechanical Denver flotation cell focusing on flotation kinetics of chalcopyrite, pyrite and molybdenite. Different flotation kinetics models including nine common empirical models and four mathematical models namely Hill, Chapman (Sigmodial function), single rectangular (Hyperbola equation) and exponential were applied to the experimental data. In addition to assessment of the goodness of fit criterion for each model, a factor of model complexity was considered using information criteria (IC) (i.e. Bayesian information (BIC), low of iterated logarithm (LILC) and Akaike information (AIC) indices). The obtained results showed that the IC indices could simply manifest the best-fitted model to the experimental data. Whereas, the coefficient of determination values (R2) were relatively same for all models. By taking the R2 and model complexity criteria into account, the exponential model was chosen as the best representative mathematical model to demonstrate chalcopyrite kinetic behavior. However, Chapman model was selected as the best one for the flotation of pyrite and molybdenite. In case of the common first-order flotation kinetics models, fast and slow flotation kinetic model (Kelsall) was reasonably fitted the best to the given data of chalcopyrite. However, the gas/solid kinetics adsorption model was chosen as the best-fitted one for pyrite and molybdenite. Furthermore, it was found that mathematical models represent better results in association with flotation kinetic behavior of chalcopyrite, pyrite and molybdenite due to the consideration of more parameters in modeling. Finally, it was concluded that the IC indices must be applied to the process of model selection due to consideration of goodness of fit, complexity of a model and model consistency.

Jan 1, 2018

By J. Y. Tian

In view of the fact that many domestic iron ore-dressing plant applying flotation cells in the re-verse flotation, to improve the technical level of magnetite reverse flotation, we apply such a technological process of one stage rougher and two stages scavenger flotation column respectively. The middling from the two stage scavenger process are returned to magnetic separation for condensing. By contrast, the technological process of one stage rougher and one stage cleaning flotation cells is made up of by multi-magnetic separation and magnetic middling regrinding separations. It has been proved that the flotation column we offer can simplify the technological process structure, obtain advanced technical indexes, run the system smoothly, reduce energy consumption, and be environ-mental friendly.

Jan 1, 2014

By Chenyang Zhang, Zhigang Yin, Wei Sun, Jingxiang Zou, Jianyong He, Yuehua Hu, Zhijie Xu

"In this work, a novel compound 4-Amino-5-mercapto-1,2,4-triazole was first synthesized and its selective adsorption mechanism on the surface of chalcopyrite was comprehensively investigated using UV-vis spectra, zeta potential, Fourier Transform Infrared Spectroscopy(FTIR), X-ray Photoelectron Spectrscpy Measurements(XPS), and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and first principle calculations. The experimental and computational results consistently demonstrated that AMT would chemisorb onto the chalcopyrite surface by the formation of a five-membered chelate ring. The first principle periodic calculations further indicated that AMT would prefer to adsorb onto Cu rather than Fe due to the more negative adsorption energy of AMT on Cu on the chalcopyrite (001) surface, which was further confirmed by the coordination bonding energies of AMT-Cu and AMT-Fe based on the simplified cluster models at a higher accuracy level (UB3LYP/Def2TZVP). The bench scale results indicated that the selective index improved significantly when using AMT as a potential chalcopyrite depressant in Cu-Mo flotation separation.INTRODUCTIONFroth flotation is one of the most important processes to separate valuable minerals from gangue by taking advantage of differences in the physical chemistry of their surface properties(Laitinen et al., 2014), particularly in their surface hydrophobicity. Hydrophobicity differences between valuable and gangue minerals could be regulated by adding different chemical additives (surfactants)(Kor, Korczyk, Addai-Mensah, Krasowska, & Beattie, 2014), such as collector and depressant. It could be conducted economically to selectively separate and enrich the complicated and/or poor ores, by adopting appropriate surfactants. For example, the beneficiation of molybdenite usually relies on a two-stage process to realize flotation separation of molybdenite from other unwanted sulphide ores(Wie & Fuerstenau, 1974). In the first step, a bulk molybdenite concentrate is produced by utilizing kerosene/ diesel oil and pine oil/alcohols as collector and frother, respectively. Second, sodium hydrosulphide, sodium cyanide, ammonium sulphide, or Nokes reagent are adopted as depressants in the separation stage. However, these depressants are usually toxicant and cannot meet the requirements of environmental protection. A large number of efforts have been taken to develop alternative environmentally-friendly depressants (Ansari & Pawlik, 2007; J. H. Chen, Lan, & Liao, 2013; Li et al., 2015; Yin, Sun, Hu, Zhai, & Guan, 2017; Yin, Sun, Hu, Zhang, Guan, Liu, et al., 2017; Yin et al., 2016). Although some novel and environmental-friendly depressants have been reported to achieve good performance in Cu-Mo flotation separation at a laboratory scale, there are still some challenging problems, including toxicity, high price or poor performance in practice, which severely limit their practical applications in Cu-Mo flotation separation on a commercial scale."

Jan 1, 2018

By Patricio Berrios, David Barriga, Peter Amelunxen, Gerson Sandoval, Roger Amelunxen

Laboratory test equipment and methods have undergone relatively little change since their introduction in the 1950’s. The Denver sub-A cell is still by far the most commonly used laboratory batch cell, but bottom-driven and instrumented cells are beginning to appear. Test procedures have also changed little over the past 60 years, and most engineers continue to rely on empirical models for predicted plant scale performance from laboratory scale tests. This approach is problematic, because changes in the froth phase characteristics in the lab hamper the reliability and reproducibility of the empirical extrapolation to plant scale. In a previous work, the authors reported on the impact of froth recovery at the laboratory cell, showing that variability in the froth recovery can lead to significant error in the modeled kinetic rate constant unless it is properly accounted for in the scale-up model. In this work, we review the role of hydraulic entrainment in the lab cell, and how variability in particle specific gravity, shape factor, and froth residence time can impact the entrainment recovery.

Jan 1, 2014

Deposit of Jinbaoshan platinum group metals (PGMs) ore ranks the second in Yunnan province, China. Study on process mineralogy shows that the grade of copper and nickel in the ore is just 0.16% and 0.20% respectively. Moreover, the impurities magnesium and iron and silicon are rich in the ore. The copper and nickel sulfides in the ore, especially the minerals of PGMs, are finely disseminated with the gangues like serpentine. Fine grinding is necessary, and high content of MgO in the concentrate is inevitable through traditional flotation technology on the basis of process mineralogy studies. Achievements on process mineralogy studies are applied to guide the flotation tests successfully. Progress on flotation has been made through comprehensive studies. Suitable grinding by two stages is required for the finely disseminated PGM sulphide ore to achieve the liberation of valuable minerals. Stage grinding and stage separation shall be conducted for a better recovery of valuable minerals. The oxidation state of mineral surface of sulphides has a profound effect on flotation of the ultra-fine sulphides, especially the pentlandite. The combined use of collectors enhances the selective collecting on the ultra-fine and low-grade valuable minerals, is of critical importance.

Jan 1, 2014

By Zhang Zhonghan

A domestic tungsten-tin ore presents very complex property. How to effectively recover the scheelite, wolframite and cassiterite in the ore has long been a difficult problem to be solved urgently. On the basis of process mineralogy study, a main flow-sheet for effective recovery of tungsten-tin minerals has been developed, which including ?fine grinding of feed?bulk flotation of all sulfides followed by their selective separation?iron recovery by LIMS?tungsten-tin minerals bulk flotation using new technique developed by our institute?tungsten-tin recovery by gravity from above tungsten-tin bulk flotation tailings?. As for the treatment of tungsten-tin bulk rougher concentrate, several flow-sheets of tungsten-tin separation by direct hydrometallurgy or a flow-sheet consisting of scheelite cleaning at elevated temperature followed by the gravity separation of scheelite cleaner tailing?separation of wolframite from cassiterite by dry HIMS or by direct hydrometallurgy are developed. For a low grade head ore, all valuable sulfide, magnetite, scheelite, wolframite and cassiterite are recovered with satisfactory in lab scale test. Keywords: micro-fine cassiterite, tungsten-tin bulk flotation, gravity separation-flotation-dry HIMS combined flow-sheet, hydrometallurgy

Sep 1, 2012

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

By Alexsandro Berger

Many thickener operations continue to be constrained by their ability to process consolidated underflows with high yield stress and associated rheological characteristics. To maximise separation efficiencies within a thickener operation the use of both engineering and reagents are always considered. BASF is developing a Novel Flocculant Technology (NFT), which combines both of these aspects to enhance the performance of the thickener operation, improving the areas of pumping efficiency, underflow density and throughput. The development progression through stages of laboratory scale batch test work to pilot scale dynamic testing has demonstrated the ability of BASF NFT to maintain effective flocculation performance whilst increasing the rate of underflow consolidation, and significantly reducing the associated underflow yield stress of the treated material. This paper will present application data through full scale dynamic testing conducted on a granite washing circuit to demonstrate the performance benefits that NFT offers to a thickener operation. Compared to the conventional flocculant treatment, within the operation parameters and conditions employed during the full scale trials, the NFT produced a reduction in underflow rheology (yield stress) of around 45 % relative to a given solids and improved the underflow consolidation by providing at least 20% relative higher underflow solids loading than the upper limit of the given typical thickener operation. Keywords: flocculation, thickener operation, rheology, yield stress, underflow density, throughput, slump test

Sep 1, 2012

By Leonardo Soto, Fernando Villanueva

"Antofagasta Minerals S.A. (AMSA), for its Centinela District Project, is currently developing, at a first stage, a new 90 ktpd Concentrator Plant incorporating Esperanza Sur (ESP Sur) and Encuentro (ENC) ores. In order to dimension properly main equipment, specifically for grinding circuit, a final decision has been taken using geological and metallurgical (comminution) data from both body ores. Data was analyzed internally within AMSA and its consultants to get a final proposed circuit for further engineering studies. Specific Energy Consumption (SEC) parameter is one of the main key factors for proper dimensioning. To get an accurate value different tests have been made and modelled to ESP Sur and ENC ores. Also, operational data from Esperanza operation has been taken into account due to its similar ore characteristics to ESP Sur ore and incorporated as input data for design. Depending on data, quality and amount, it is possible to estimate accuracy for project investment and risk level, hence investment decision can be taken under good and reliable information."

Jan 1, 2014

By T. Inoue, K. Okaya

"Movement of mill charge in the centrifugal mill is essentially different from that in the vibration mill with circular path despite the apparently similar mode in the motion of mill body. As proved e.g. in [11], this results in substantial advantage regarding the comminution intensity of the centrifugal mill over the conventional vibration mill accounting approximately to one order of magnitude.Back in 1983, Bradley et al. presented a model of the centrifugal mill based on the kinetics of the mill charge by regarding it as a lumped mass. On the other hand, numerical modeling by ‘discrete element method (DEM)’ enabled us to observe the movement of each ball in the centrifugal mill with an extremely minute time intervals (Inoue et al., XX IMPC in 1997). The former approach rendered simple, even though approximate, expression of the mill behavior, while the latter method was advantageous in describing the behavior of the mill in terms of individual events taking place in the mill body, even though the result did not reduce to a simple expression. The characteristics of the centrifugal mill described by both these approaches proved to be in a degree of agreement. Thus, the kinetic approach was capable of presenting the overall view of the mill, while the DEM model was informative of the details that could not be depicted well enough by the simple math expressions."

Jan 1, 2003

By O. Martinsson

The Kiruna area is an important mining province in northern Sweden, which is dominated by Fe- and Cu-Au deposits. Economically most important for the region, are the apatite iron ores with an annual production of c. 43 M ton of crude Fe-ore and a total production of more than 2000 M ton of ore the last 100 years. The apatite iron ores in the Kiruna area are dominated by either Magnetite or Haematite and contain varying amounts of apatite giving them a content of Fe and P, which varies between 30-70 % and 0.05-5 %, respectively. A typical geochemical feature of the ores is the strong enrichment of REE that is caused by a high content of REE in apatite and the occurrence of Allanite and Monazite containing 22.4 and 69.8 wt% REO, respectively. At Kiirunavaara, the content of REE in apatite varies between 0.07 to 1.57 wt% REO with a dominance for the light rare earths. The variation in REE-content of apatite depending on textural and paragenetic aspects is not known but apatite grains may display a strong LREE-depletion due to hydrothermal alteration. Monazite occurs as rod-shaped or tabular inclusions in apatite and is suggested, to have formed in response to hydrothermal alteration of apatite after the emplacement of the ore. Inclusions are mainly found in the central part of apatite grains occurring in veins and schliren, while they are rare in apatite occurring disseminated in the ore. Monazite also occurs as larger grains outside apatite and together with Allanite is found in texturally and paragenetically different settings within the ore. These occurrences of REE-minerals may largely be a product of LREE mobilized by alteration of apatite after the emplacement of the ore. However, REE-minerals including Allanite and Monazite might also have formed directly from late magmatic fluids. Keywords: apatite, monazite, allanite, ree, kiirunavaara, iron ore of kiruna type, mineral chemistry

Sep 1, 2012