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By Shuoshi Lu

The Cu-Co ore studied here belongs to the oxide type. The oxidation rates of copper and cobalt are69.30% and 78.78%, respectively. The content of Cu in ROM is 1.34% and that of Co is 0.096%. The ore contains 4.64% carbon.Based on the process mineralogy and previous metallurgy tests, the principalprocess flow-sheet of ?grinding fines 80% -0.074mm, sulphide flotation followed by oxide flotation, and flash flotation for oxides? has been determined.The handling of carbon is determined through tests. The depressant PNL-1 depressed carbon effectively, improved the recovery of sulphide minerals and reduced the reagents consumption.The operation of the flow-sheet was also changed to better at the same time. Keywords: Cu-Co oxide ore, process mineralogy, carbon depression, efficient depressant of carbon

Sep 1, 2012

By Liu Xiaodong, Jiang Meifen, Kou Xiaoyan, Lu Xianjun

"Two low grade calcium bentonite (Ca-bentonite) from Hejia (HJ) and Boteng (BT), Shandong, China, mainly contain montmorillonite and quartz, and slightly feldspar, calcite, and montmorillonite content are 32.37% and 55.90%, respectively. In order to examine the feasibility to produce activated clay to meet the standard of Chinese chemical industry (HG/T2569-2007), three types of industrial production process are proposed according to the screen test. The first process is grinding the raw bentonite to -200 mesh and then activating. The second is to activate the raw bentonite directly, and then classify the production to -200 mesh. The last one is to activate the raw bentonite after purification. Three parameters, which are sulphuric acid strength, ratio of liquid to solid and treatment time, are optimized via orthogonal test for every process. The preliminary test indicates that it is feasible to produce acid bentonite of difference quality. For the sample of HJ, milling the raw to -200 mesh first and activating afterwards, the parameter is at 9% acid strength, the ratio of liquid to solid 2, the time 4 hours, temperature 90°C, the products can meet the qualified grade for animal and vegetable oils refining. For the sample of BT, milling the raw to -200 mesh first and activating afterwards, the parameter is at 15% acid strength, the ratio of liquid to solid 2.5, the time 2 hours, temperature 90°C, the products can meet the qualified grade of high decolorization for petroleum products refining. For the sample of BT, adopting purification to -325 mesh by stirring and rubbing at first, and then activating at 9% acidity, under the conditions that the ratio of liquid to solid is 2, the time is 2 hours and the temperature is 90°C, the products can meet the first grade of high activation degree for petroleum products refining."

Jan 1, 2014

By Kwan Ho Kim

In this study, free fall tests are conducted with the objective of understanding the breakage properties of waste concrete for the guide of the direction of the better comminution process. Waste concrete of 75mm×53mm is tested at various drop heights with or without heat pretreatment. Test results indicate that a block of waste concrete does not break by free fall, but eventually breaks by repeated free falls. The number of free falls required for complete separation of large aggregates from the cement mortar considerably reduced when the samples were heated at 400?. Therefore, a great energy saving can be obtained when heating the waste concrete prior to crushing. The energy saving was found to be dependent on the height of free fall but in all cases, was still large enough to offset the additional energy required for heating. Also, it was found that the heat pre-treatment gives an additional advantage in that it produced cleaner recycled aggregates. This may result from easier detachment of cement mortar from the aggregates due to weakening of bonding forces by heating. By analyzing the size distribution of the crushed product, a free-fall breakage model is developed using the particle breakage ratio and the breakage pattern. The developed model can be used to predict and to analyze waste concrete processing circuit.

Jan 1, 2014

By Z. G. Song, C. Y. Sun, X. R. Zhang, Y. Yu

In skarn type scheelite deposit, there are calcium minerals with floatability similar to scheelite, such as calcite, fluorite, etc., which are difficult to separate. Heating cleaning method developed by Petrov has been widely applied in processing rough concentrate of scheelite for nearly half a century, but there exists a general lack of full understanding of the interaction between floatation reagent and mineral particles surfaces. The mechanism on separation of scheelite and calcium minerals in heating cleaning process was investigated by mineral flotation experiments, XPS analysis, as well as solution chemistry and crystal chemistry calculations. The results showed that the sequence of minerals floatability using sodium oleate as collector and a large amount of sodium silicate as modifier in heating flotation test was scheelite > calcite > fluorite, which was the same as solution chemistry calculations based on Gibbs free energy vs. pH and also the same as Ca-X intensity order by crystal chemistry analysis. There are two sides about the mechanism of heating cleaning method: one is that the adsorbed collector on calcium minerals surface is desorbed more easily than scheelite, and the other is selective dissolution of calcium ions from the mineral surface because of Ca-X intensity difference in heating and stirring process.

Jan 1, 2014

By Venkataramana Runkana, Aditya Pareek, Vishnu Masampally, Nagaravi Kumar Varma Nadimpalli

"Recovery and grade of the ore produced are two important metrics, which define the profitability of a mineral processing plant. Achieving high grade and high recovery at the same time in a mineral processing plant is difficult due to conflicting nature of the two objectives. To explore the operability limits of the plant operations and find the set of operating conditions that can help achieve the best possible recovery and grade, there is a need to solve a multi-objective optimization (MOO) problem. Past research focused on building a plant-wide simulation model or on optimization of individual units or a part of a mineral processing plant like grinding circuit, crushing circuit, etc. However, it is necessary to consider optimization of the complete plant in order to optimize the plant performance. Here, we have formulated the mineral processing plant performance optimization as a MOO problem. We have applied machine-learning algorithms such as random forest to build models to predict the recovery and grade of the ore. A non-dominated sorting-based multi-objective evolutionary algorithm called NSGA-II (Non-dominated Sorting Genetic Algorithm II) was employed to solve the MOO problem. Since the number of parameters that influence recovery and grade are quite large, we have applied machine-learning algorithms for feature selection or identification of key process variables. Pareto optimal conditions were determined for manipulated variables like grinding mill throughput, speed ratio at SAG mill, speed of centrifugal pump, water addition at different locations etc. The results obtained are useful in identifying the operability of a mineral processing plant to achieve the optimum grade and recovery for a given feed grade and the processing circuit. INTRODUCTION Copper is majorly mined or extracted as copper sulfides from large open pit mines in porphyry copper deposits. Among all the available ores, sulfides are the most commercial ores, especially chalcopyrite (Greenwood and Alan, 1997). Copper grade in these ores generally lies between 0.4 to 1.0%. In order to perform smelting operation, the grade of copper has to be improved to around 30% (Biswas et al. 2013). This targeted copper grade is achieved through two stages of mineral processing. Firstly, the copper in the ore has to be liberated by crushing the mineral rock. Secondly, the liberated copper in the crushed ore is then physically separated from other minerals like nickel by froth flotation techniques."

Jan 1, 2018

By M. Surracco, M. C. Tilocca

"Mineral comminution is often a costly process which also requires high level of energy. In the course of the studies carried out by the researchers of the Department of Civil-Environmental Engineering and Architecture at the University of Cagliari, aiming at the optimization of the reduction processes, it has been experimented, among of others, the effects of high-speed water jets on minerals grinding. As far as coal is concerned, some of the solutions initially adopted are presented in this paper, which essentially relied on the water jet power only, with secondary use of mechanical actions, to reach the most modern solutions that envisage the use of mechanical energy, normally used in traditional grinding machines, in synergy with hydraulic energy transferred by water jet.INTRODUCTION Mineral comminution can be rather expensive and demand a high-energy consumption, especially for fine sizes (Austin, 1979). Further interesting perspectives in this area may be offered by comminution means aided by high pressure water jets (Ciccu 2007), whose crushing potential is currently used for several operations such as cutting different materials, rock digging and industrial cleaning. The crushing action of water jets may induce a traction stress in materials where substances of a mineral nature, especially if characterised by permeable porosity, oppose a minor resistance (Griffith, 1920). The first solutions to this purpose essentially relied on the sole energy of water jets, with a secondary use of mechanical actions (Ciccu, 1993). Results were encouraging, despite the high values of specific energy for the low capacity of treatment. However, due to the difficulty in making the techniques mainly based on hydraulic energy practically applicable to solids comminution a solution was experimented, with some interesting results, consisting in the combination of mechanical energy, normally used in traditional grinding devices, with hydraulic energy transferred through water jets, in a synergic relationship (Ciccu, 1998; Tilocca, 2016)."

Jan 1, 2018

By P. Oliveira, A. Peres, A. Silva

"The decrease in iron content and increase in contaminants grade, associated with greater participation of compact and semi-compact materials, has impacted the recovery of a mechanical cells flotation circuit in the Iron Quadrangle, Brazil. The recovery decrease in the flotation stage motivated the current conventional flotation circuit reevaluation seeking alternatives to restore the recovery, without affecting the final concentrate quality parameters, with low investment. Sampling, chemical characterization of samples, bench scale flotation experiments, and mass balances were conducted. Analysis of the results showed opportunities to improve the circuit performance. The stages prior to the flotation circuit changes were: rougher, cleaner, recleaner and scavenger. In the previous configuration, recleaner was operated as cleaner scavenger and the iron grade in the scavenger concentrate was 23%, representing 38% of the new feed. After the circuit change, the circulating load was reduced from 38% to 15% and the iron content was upgraded to 42%, resulting in increased residence time. The iron content in the global tailings of the concentrator was decreased from 10.9% (year of 2013 average) to 10.2%, representing gains in both mass and metallurgical recoveries.INTRODUCTIONRegarding plant practice, the year 1972 represents a landmark for the concentration of iron ores in Brazil. VALE started up 28 units of WHIMS (wet high intensity magnetic separators) at the Cauê plant in Itabira, each one producing 1x106 t/year of concentrate. Later 17 WHIMS machines were commissioned at Conceição. During the 80’s decade of last century, changes in the ROM required the addition of a cleaner flotation stage to decrease the silica content in the pellet feed.The first company to use reverse cationic flotation as the only concentration operation of iron ore was SAMARCO (start up in 1977). Since 2015 flotation has been utilized at VALE in Itabira as major concentration process, magnetic separation acting as scavenger stage.The Jones matrix type WHIMS were manufactured for decades under patent by KHD Humboldt Wedag. After the expiration of the Jones patent, Eriez Magnetics took the world leadership regarding WHIMS manufacturing. The Brazilian branch of Eriez is Inbras. Based on plant practice experience at the Fabrica concentrator, the Brazilian company Gaustec was established (RIBEIRO and RIBEIRO, 2010) and is now present in different countries. The mega sized WHIMS GHX-1400 (18.000 Gauss, gaps smaller than 1.5 mm) were developed to face the challenge of huge throughput required by iron ore processing (Ribeiro et al, 2017)."

Jan 1, 2018

By I. A. Agapov, I. S. Anisimov, N. V. Rylov, A. M. Sagitova

"The smelter slags represented silicate crystalline rock with medium to coarse-grained structure with spinifex skeletal network of olivine in hedenbergite matrix. Accessory magnetite, pyrrhotite and copper sulfides chalcopyrite, bornite, covellite, chalcocite and digenite occurred in dissemination in silicate matrix. The sample was studied by optical and electron microscopy with support of quantitative XRD. Modal mineralogical composition included olivine, pyroxene, magnetite, chalcopyrite, quartz, pyrrhotite. Copper deportment showed copper distributed in chalcopyrite (40 %), cuprite (22 %), covellite (21 %), bornite, chalcocite, digenite (5 %), Cu-bearing pyrrhotite (4 %) and spinel (2%). Liberation of copper minerals in the material ground to P80=71 µm was good with over 90 % sulfides in free grains and floatable binaries. The results showed theoretical possibility of 65 % copper recovery by flotation. Conclusion based on mineralogical data was precisely confirmed with flotation tests studies that proved to recover around 60 % of copper to commercial grade concentrate. INTRODUCTION Annual world copper matte smelter slags production is estimated to be millions of tones and contain thousands tones of unrecovered Cu, Zn and significant amounts of Ag and Au. Mineralogical study of one large processing sample of material of historical piles of Cu matte smelter slag was carried out to find possibility to recover copper and define theoretical recovery by flotation. The study of the slag material was aimed to determine possibility of upgrading the material on existing copper flotation plant to develop additional mineral resources. The objectives for mineralogical investigation were to target for best liberation fineness, determine theoretical recovery and possible concentrate quality for sulfide flotation tests. MATERIALS AND METHODS Large representative processing sample was collected by mixing of 120 t of slag material representatively excavated from historical piles of Cu matte smelter slag. The sample was used to define the processing technology to recover copper and gold from the material."

Jan 1, 2018

By B. Rai

Processing of dolomitic phosphate ores remains one of the most challenging problems in phosphate ore beneficiation. The beneficiation plant at Jhamarkotra in Rajasthan, India for example is currently using a conventional double stage flotation process which involves first a fatty acids flotation to produce a combined dolomite-apatite concentrate (bulk concentrate) from associated silicate gangue. Dolomite is then separated from this bulk concentrate by flotation with fatty acids collectors and depressing apatite with phosphoric acid and sulphuric acid. This process requires addition of large dosages of reagents (H3PO4 and H2SO4) to depress apatite and to maintain highly acidic pH during flotation. Furthermore several cleaning and scavenging stages are needed to obtain the product of desired quality. We have developed and employed a molecular modelling based methodology of designing selective reagents for apatite-dolomite separation. We have been able to take into ac-count the differences in the distribution of calcium cations on these two surfaces in our design and hence develop novel phosphonic acid based depressants for apatite-dolomite separation with con-ventional fatty acids as flotation collectors. We have demonstrated the utility and power of molecular modelling based reagents design approach through this work on beneficiation of Jhamarkotra dolomitic phosphate ore using our novel phosphonic acids based depressants at pH?s close to natural pH. It was possible to reduce the MgO content of the ore from as high as 13.3 % to 1.5% in a single stage flotation. Our flotation separation results on Jhamarkotra ore with these new phosphonic acids based tailor-made depressants for apatite-dolomite flotation separation are discussed in this paper along with results of corresponding molecular modelling computations on the same system.

Jan 1, 2014

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

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

Jan 1, 2014

By N. S. Phala

Declining gold grades, mineralogical complexity of ore bodies, increasing input costs, more stringent conditions in the licenses to operate, and uncertain gold price dynamics combine to exert significant ongoing pressure on margins of gold producers. Innovative approaches of extracting the metal from its ores are required to realize value from existing and future assets. In a conventional gold processing plant, size reduction of mined ore to produce floatable or leachable product is a significant cost contributor. A step change in cost reduction will be attained if radically energy efficient grinding approaches can be developed, replacing tumbling mills. In the path towards that goal, some quick wins are possible through waste rejection before grinding, and pre-treatment of mill feed to reduce grinding energy demands. Gold locked in complex mineralizations puts pressure on margins by increasing cost per oz (typically high $/t and low metal recoveries) in the hydrometallurgical steps. Gold miners are primarily price takers. The current narrow range of gold uses (predominantly investment and jewellery) is not an entirely desirable state. Some diversification into commercial uses would potentially be a price stabilizer. In this paper, promising research directions, some not always fully explored in the gold metallurgy research space, are highlighted to stimulate radical innovation for substantial value enhancements. The author strongly believes a shift from a traditionally conservative and incremental innovation approach to a more aggressive one, across all aspects of the gold metallurgy value stream (processes to products), is what the industry needs. Keywords: gold metallurgy value stream, thiobaccilus ferroxidants, HPGR

Sep 1, 2012

By N. Dhawan

In the last decades, High Pressure Grinding Roll (HPGR) has gained significant importance in hard rock processing due to numerous metallurgical benefits such as energy savings, particle weakening, preferential damage of coarse particles, and preferential comminution-liberation. There are a limited numbers of lab-scale HPGR units throughout the world. The laboratory-scale HPGR machine at the University of Utah is first-ever lab-scale machine designed by late Dr Klaus Schönert, the inventor of HPGR. This HPGR is constructed with two counter-rotating hardened tool steel rolls, each 200 mm in diameter and 100 mm in width. The HPGR unit is equipped with eight sensors and a robust control system, which serves as an ideal system for fundamental studies and lab-scale testing. In HPGR operation, throughput, energy and product size distribution are intricately linked to specific grinding pressure, roll gap and rolls speed. The nip angle existing during the operation determines the volume of feed material above the rolls that is pulled into rolls without slip. In this paper, scale-up factors and some of the existing models have been reviewed. A number of experiments have been carried out with limestone and a slag material. The influence of operating variables and their complex relationship has been studied.

Sep 1, 2012

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 Irena Grigorova, Tashka Ignatova, Ivan Nishkov, Andrian Valchev

"Feldspars used by ceramic and glass industries as fluxing agents are mainly obtained from high quality feldspar deposits. The demand for feldspar as raw material for industrial applications especially in ceramic manufactures is continuously increasing. However, due to the depletion of those deposits, the research activities related to the recovery of feldspar from the lower grade feldspar deposits and feldspar bearing rocks such as pegmatite, granite, arkosic sandstone and syenite have been intensified in the last two decade. In Bulgaria, the main deposit of arkosic sandstone is located in the area of Shumen town, NE Bulgaria. In Srednya deposit arkosic sandstones are found in Upper Cretaceous sediments (Santonian). In this formation, there are two major industrial minerals - feldspar and quartz. They may be of economic value and possibly suitable for commercial uses. The main purpose of the present study was to investigate the beneficiation and upgrading processes of Srednya deposit arkosic sandstones. In a laboratory scale it was studied the possibility to obtain the feldspar concentrate and quartz sand from arkosic sandstones. Particle size distribution, chemical and mineralogical compositions of quartz-feldspar sands were determined. The bench-scale tests using the KOALIN AD laboratory experimental facilities were conducted. Many processing techniques were tested: disintegration, washing, sizing, carbonate flotation and feldspar flotation. The experimental results show that there are possibilities to obtain the silica sand with low content of Fe2O3 - below 0.02 % and potassium feldspar with content of K2O > 14 %. A new technology for recovery of feldspar and silica sand from arkosic sandstone was developed."

Jan 1, 2014

By Mohana Rao Andavarapu

Sandur Schist Belt of Karnataka Craton constitutes a hub of iron ore mining activity. The iron ore deposits of the region are closely associated with Banded Hematite Quartzite (BHQ), Shale, phyllites, & Graywackes. The gradual depletion of high-grade iron ores due to extensive utilization has necessitated the exploitation of low-grade iron ore including BHQ, which are available abundantly in different parts of India. In the present investigation, BHQ samples from Kammaturu mines of Sandur schist belt was studied to assess the possibility of upgrading the iron content to the maximum possible extent, so that it may find the better use in iron and steel industries. The sample collected from the study area analyzing 39.76% Fe, 39.8% SiO2, 0.66% Al2O3, and 1.92% LOI was subjected to beneficiation studies. The mineralogical studies reveals that the samples are predominately consists of hematite as an iron mineral and quartz as gangue mineral. Liberation studies and chemical analysis were carried out prior to the beneficiation process, which is flotation. Cationic Reverse flotation studies were carried out and discussed by varying different process variables such as feed size, depressant, collector cum frother dosage & pH. The results obtained are encouraging with an appreciable improvement in the iron content up to 62.8% Fe with Fe recovery of 50.43%. The concentrate obtained from the flotation can be used for pellet making process.

Sep 1, 2012

By Chris Plackowski, Bruckard. Warren J., Anh V. Nguyen

"Enargite is a significant penalty mineral in the copper industry and its separation from many copper sulfides by flotation is difficult. The separation may be crudely achieved using selective oxidation techniques or through the use of pulp potential control. This paper summarizes our latest contributions to a better understanding of enargite surface electrochemistry and hydrophobicity. Oxidation, roughness, hydrophobicity and species formation on the surface of natural enargite were examined by a novel experimental approach that combines electrochemical techniques, atomic force microscopy, X-ray photoelectron spectroscopy and droplet evaporation tensiometry. It allows for synchronized electrochemical control and examination of the oxidative surface morphology, speciation and hydrophobicity of enargite at pH 4 and pH 10. At low pH, surface layer formations consisting of metal deficient sulfide and elemental sulfur were identified associated with a limited increase in roughness and heterogeneous distribution of surface species produced by initial rapid dissolution of Cu, followed by diffusion limited surface layer deposition. At high pH, a similar diffusive mechanism associated with oxidation products consisting of copper sulfate and hydroxide and a significant increase in surface roughness were established. Receding contact angle measurements showed no significant difference in the contact angle on a surface oxidized at pH 10 and the freshly polished surface. Contact angle increased from 46° on the polished surface to 59° after oxidation at pH 4. Competing effects of hydrophilic copper oxides and hydroxides, and hydrophobic species of elemental sulfur on the mineral surfaces under oxidizing conditions at pH 4, and the change in surface roughness at pH 10, contribute to the changes in enargite hydrophobicity under electrochemically-controlled oxidation conditions. Most likely, both surface species and surface roughness produced by oxidation are critical to the changes in the wettability of enargite and other sulfide minerals."

Jan 1, 2014

By B. K. Mohapatra

Small manganese ore bodies in south Odisha, India occurs both as stratiform and stratabound ore bodies. These two ore bodies show contrasting mineralogical, petrographical and chemical characteristics. Stratiform type of Mn-ores consists of manganese, iron and silicate- phases in approximately same proportion. In contrast, stratabound ore bodies contain a high proportion of manganese oxides, silicates and phosphorus phases. Phosphorus is found within apatite in the stratabound ore bodies while in the stratiform ore it occurs as an adsorbed state with iron phase (goethite). Both ore bodies are low-grade (17-23% Mn) therefore do not have a market value. However, the stratabound ores are enriched in phosphorus (P2O5: >1%) compared to the stratiform ores. Both the ore types were processed through gravity, magnetic and roast reduction followed by magnetic separation techniques. The strata bound ore could be upgraded to 33% Mn from a feed of 23% by combination of dry and wet magnetic separation methods. But the phosphorus content also suits up (P2O5: 1.2%) in the processed product making it unsuitable for further use. The stratiform ores do not respond to either gravity or magnetic separation because of close association of manganese with iron phases. However, this could be beneficiated through roast reduction followed by magnetic separation. An ore with 17% Mn content could be upgraded to 40% Mn with a 42% yield and 78% recovery. The goethite, having phosphorus, converts to magnetite and is retained within the magnetic fraction, thereby reducing the concentration of phosphorus in the non-magnetic fraction, which becomes the product. This report demonstrates the influence of ore petrology in determining the up-gradational potential of manganese ore in the southern Odisha, India. Keywords: manganese ore, physical beneficiation, phosphorus rich ore

Sep 1, 2012

"The most common agglomeration technique in iron and steelmaking is sintering, which requires the use of iron ore/concentrate mixtures, limestone and dolomite as fluxes and coke as fuel in order to produce the required melt at high temperature to cause agglomeration of the particles. Sinter feed blends containing high proportions of magnetite concentrate are difficult to granulate and to produce granules of high permeability, and sufficiently robust quasi-particles for successful sintering operations. Since the granulation of iron ore sinter feed requires no use of a binder, the added fluxes play a vital role in holding the granule particles together until they sinter. The fluxes also help to improve the granule quality and control slag composition in the blast furnace. It is well-known that the particle size distribution of the fluxes affects the granulation effectiveness and green bed permeability which determine the productivity, physical and metallurgical properties of the granules and sinter. Hence it is necessary to understand the role of flux particle size on granule properties so as to improve the granulation of iron ore sinter feed blends containing high magnetite concentrate. In this study, laboratory granulation experiments have been carried out on iron ore sinter feed blends containing high proportions of magnetite concentrate at different addition levels of limestone and dolomite mean particle sizes, to understand the influence of limestone and dolomite particle sizes on granulation rate processes and granule properties.INTRODUCTION Increases in iron ore production to meet the global demand for iron and steel products has led to the depletion of high grade iron ores and thus the current utilisation of low grade iron ore fines and concentrates. However, sinter, pellets and the lump are the required feed types used in the blast furnace. The high basicity sinter is the main iron bearing feed accounting for 70-85% in the blast furnace due to its good metallurgical and mechanical properties that allow high productivity, efficient processes and low production cost (Adam et al., 2017)."

Jan 1, 2018

By T. N. Alexandrova

Results of mineralogical-technological research of carbonaceous rocks of Kimkansky precious metal occurrence are presented, on their basis new typemorphic natural and technological microelement associations were revealed using mathematical statistics methods. Keywords: carbonaceous rocks, processing, microelements, flotation, statistical criteria

Sep 1, 2012

By K. D. Mehta

Copper concentrate containing complex sulphides of Cu-Ni with 14.13% Cu and 10.04% Ni besides impurities such as 0.33% Co and 0.71% Mo, is not acceptable to the copper smelters due to the smelting problems. Selective bioleaching of nickel from the concentrate can be considered an an option to make it suitable for copper smelter. Effect of elemental sulphur and pyrite on the bioleaching of Ni and Co has been investigated using a mixed culture of Acidithiobacillus ferrooxidans (A.f.) and Acidithiobacillus thiooxidans (A.t.). Parameters such as pH, temperature, particles, size etc. were optimised to understand the role of additives in the bioleaching. With 2% S at 308K, 2.0 pH, 5% pulp density and 200µm size particles while shaking at 100 rpm, 79% Ni, 41% Co and 5% Cu were bioleached as compared to the leaching of 81% Ni and 45% Co in presence of 10 wt% pyrite in 60 days; 27% Ni, 24% Co and 4% Cu were recovered in sterile experiment. The selective dissolution of nickel and cobalt as compared to copper may be explained by galvanic interaction between chalcopyrite: pentlandite / pyrrhotite. Bioleaching was facilitated by strong oxidizing conditions due to higher Fe3+/Fe2+ ratio/redox potential (ESCE) as a result of improved interaction of minerals through biooxidation of sulphur and accelerated galvanic interaction by pyrite. The mechanism of selective leaching of Ni and Co was established by XRD phase identification.

Sep 1, 2012