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By J. E. Gebhardt

Progress is reported on capturing the effects of gangue chemistry in the context of a comprehensive stockpile heap leach model for leaching copper sulfide ores, employing leading edge computational fluid dynamics (CFD) technology. The stockpile is a complex multi-phase process, comprising of a solid porous media, with complex fluid flow, gas and liquid phases, competing solid-liquid reactions, dissolution of minerals and transport through the heap. The model accounts for many of the challenging physical and chemical features of the heap, including transport and reactions kinetics for the important copper and iron sulfide minerals, ferrous oxidation, bacterial effects, thermal energy, acid and sulfate balances. In this contribution, the model has been extended to incorporate dissolution of various species from gangue reactions and precipitation of hydronium and potassium jarosite, ferric hydroxide, alunite, and gypsum. The effect of aeration on the simulation of a copper sulfide heap leach is provided as an example.

Sep 1, 2012

By João Queiroz, Cristian Marquez-Sarmiento, Luiz Teixeira

The removal of various metals from process waters and effluents is usually done by precipitation of the corresponding hydroxide. Manganese however is one metal that does not respond efficiently to that approach. It may be seen in its eH X pH diagram that the way of oxidation to Mn IV rather than hydrolytic precipitation of the Mn II ion as its hydroxide, is the way to efficient precipitation of Mn in the pH range 6 to 10. We studied the use of oxidants O2; NaClO; H2O2; Caro´s Acid (H2SO5) and the combinations of O2 or H2O2 with Na2S2O5, and H2O2 with NaClO, for the oxidative precipitation of Mn from synthetic solutions starting with 10 mg/L Mn, at 25 oC. In adequate conditions, which include pH > 8, it is possible to reach final [Mn] less than 0.1 mg/L in 60 minutes of reaction time.

Jan 1, 2014

By M. L. Wu

A moderately thermophilic acidophiles strain had been isolated from the bio-heap leaching plant in Zijinshan Copper Mine, and the identification based on the PCR-16S rRNA gene sequence homology analysis with morphologic and physiologic methods was conducted by polyphasic taxono-my and phylogeny research. The results show that the strain by depurated belongs to Acidthiobacillus genus and is considered as Acidthiobacillus albertensis.

Jan 1, 2014

By Sunil K. Tripathy

Particle characteristics such as size, density, liberation and magnetic susceptibility play vital role in magnetic separation technique. To understand the performance of magnetic separation process for chromite beneficiation industry, particle characteristics need to be analysed. However, to date, this has been an expensive and time consuming task, thus only minimal amounts of this type of data are available in the literature. Several new methods are being developed, that will produce the required mineralogical and liberation data to provide processing information rapidly and inexpensively. Among these, QEMSCAN is a unique and advanced characterisation equipment used for liberation analysis for different ore whereas S.G. Franz Isodynamic Separator for determining the magnetic susceptibility. In Indian chromite deposits, the content of iron bearing minerals in the ore is typical which controls the Cr:Fe ratio in the product while treating in gravity based beneficiation plant. In the present investigation, detailed characterisation of two distinct chromite ore samples from Sukinda chromite deposit, India, was investigated which includes advanced mineral characterisation using QEMSCANand magnetic susceptibility measurement by using Frantz Isodynamic separator, etc.. Presence of haematite and gibbsite along with chromite mineral were identified as major gangue minerals in the high grade ore from XRD pattern whereas Goethite, Quartz, Haematite, Kaolinite, Ringwoodite identified in the low grade ore. The mass magnetic susceptibility of low grade ore is very high 5.2 cm3/g compared to 2.7 cm3/g for high grade ore, due to the presence of abundant quantity of iron bearing minerals. Subsequently, these two types of ore were subjected for magnetic separation for improving Cr:Fe ratio by using different magnetic separators viz. induced roll magnetic separator, wet high intensity magnetic separator, rare earth roll magnetic separator, rare earth drum magnetic separator. The results of magnetic separation studies indicated that, Cr: Fe ratio of the chromite ores can be improved to 3.99 and 1.97 from the feed assaying 3.09 and 1.29 respectively. Studies on rare earth roll magnetic separator indicated that both the ores were upgraded to a maximum Cr:Fe ratio level at optimised condition. Keywords: characterization, QEMSCAN, magnetic separation, rare earth roll magnetic separator, industrial mineral, chromite

Sep 1, 2012

By David Deglon, Martin Harris, Mehdi Safari

This paper investigates the effect of energy input on the flotation of galena in a novel oscillating grid flotation cell (OGC). Oscillating grids generate near ideal hydrodynamic environments, characterised by turbulence which is relatively homogeneous and isotropic. Previous work was limited to quartz (-100 µm). Galena (-150 µm) was floated in the OGC at power intensities from 0.5 to 3 W/kg using 0.13, 0.58 and 0.82 mm mean bubble sizes (d10) and at three collector dosages. Results show that the effect of power intensity on flotation kinetics is strongly dependent on both particle and bubble size. For fine particles (-19 µm), increasing energy input increases the flotation rate at a low collector dosage but leads to an optimum at both the moderate and high collector dosages. For intermediate particles (+19-38 µm), increasing energy input has no effect on the flotation rate at the low collector dosage but leads to an optimum at both moderate and high collector dosages. For coarse particles (+38-150 µm), increasing energy input has no effect on the flotation rate at the low collector dosage and leads to a general decrease at both moderate and high collector dosages. Optimum conditions for fine particles are using small bubbles at a moderate collector dosage and an energy input of around 2 W/kg. Optimum conditions for moderate particles are using small bubbles at a high collector dosage and energy inputs of around 1.0 W/kg. Coarse particles do not benefit from agitation.

Jan 1, 2014

As a kind of collector, Xanthates are generally used to make sulfide minerals hydrophobic in flotation process. Xanthate adsorption on a galena surface has been widely studied experimentally. In this paper, DFT methods were employed to investigate the local adsorption interactions about the collectors,such as ethyl xanthate (CH3CH2OCS2?, EO) and ethyl trithiocarbonate (CH3CH2SCS2?, ES), absorbing on two different PbS clusters. From the results, it can be easily found that, on the edge or at the apex, both collectors, with two S atoms bidentate coordinating on the clusters, have surprising interaction energies, while on the surface, its interaction is relatively weak in the form of monodentate ligand. NBO analysis results reveal that there is at least a covalence bond with sulfur atom about 10% and lead atom about 90% when the absorbed lead is on the lattice edge or at apex, but, if the absorbed lead is on the lattice surface, no covalence band would be found. Meanwhile, the S-Pb bond, formed by the absorbed Xanthate and galena lattice, seems to have much more covalence characteristic than that formed in the PbS lattice inner. Furthermore, those data also imply that the difference of the collecting effect between the EO and the ES may be not notable, because of the similar distance and the interaction energy for the same interaction mode.

Jan 1, 2014

By L. M. Wang

Chengmenshan Copper Mine Concentrator adopts the new process of preferential?bulk stage floatation and utilize reground, largely increase the mineral processing index of the copper and the sulphide concentrates. In addition, the paper describes the remarkable economic benefit of the new process through the comparison of the new and the old processes.

Jan 1, 2014

By D. X. Chen

Comprehensive utilization of the copper associated with the complex lead and zinc sulphide ore is a recognized and difficult technical issue in ore dressing field. Qi Baoshan lead-zinc mine is a typical complex copper-lead-zinc polymetallic ore deposit and difficult to process. The application of the. traditional process is not able to make the substantive progress. According to its mineralogical characteristics, the association of copper minerals with lead minerals is very close, and their particle sizes are very fine, and the copper and lead minerals are partially oxidized. Based on the laboratory tests and comparison between different process flowsheets, preferential flotation of copper minerals, being suitable for this ore, was chosen to recover copper. The separation of copper from lead applies the following technology: regrinding middlings with cyclones to classify, which improves copper lead mineral liberation, and increases copper and lead recovery; using new high-efficient collector with good selectivity, which is able to float copper minerals; and non-toxic combined depressant which depresses lead minerals. The above technical innovation, optimizing the process flowsheet, overcoming the complex traditional process flow with high production cost, obtained good technical and economic indicator. The difficult technical problem of copper lead separation was solved smoothly. After successful performance of the bench-scale experiment, commercial-scale test was carried out. In industrial trial, a copper concentrate containing Cu18.60 %, Pb7.40 % and Zn2.50 % was obtained with copper recovery of 58.49%, lead concentrate quality improved largely. The process opened up an unique path for the comprehensive recovery of Cu from similar lead and zinc non-ferrous metals mineral to comprehensively recover copper.

Jan 1, 2014

By R. M. Zhao

The process conditions and mineral characters of cleaning separation stage in magnetite concentration plant are studied in the paper, and the affecting factors and the methods to increase the concentrate grade are analysed and given. The BKJ cleaning special drum magnetic separator is developed specially for the cleaning stage according to process conditions and mineral character. The separation mechanism, structure characters, separation process and excellent adaptability of BKJ special magnetic separator are described. The results in Zhangjiawa Concentration Plant show that the BKJ special drum magnetite separators play an important role in increasing the concentrate grade and improving the economic benefit.

Jan 1, 2014

By Y. Tang

The paper studied the extraction characteristics of the fly ash from a location in Guizhou province. Under ordinary pressure, the fly ash is extracted by an acid and alkali, and then studied for its reaction characteristics with different extraction agentia, temperature, consistence and time. The results of acid extraction show that there are good reaction characteristics for Fe2O3 with HCl and the extraction rate decreases with the increasing of extraction time. There are good selective characteristics between Al2O3 and H2SO4 and they weaken with the increasing of temperature and the expanding of time. The best extraction results are shown with CaO and MgO because of their chemical characteristics and the over-saturation degree of the extraction processing. In addition, It?s found that it cannot leach all the substances from fly ash even with the higher consistence (10mol/L) of extraction agent, the longer extraction time (2h) and the higher temperature (100?) .It shows that the extraction rate of Fe2O3 is 82.81% and that of Al2O3 is 29.01%. The results of alkali extraction show that the extraction rate increases with the consistence of extraction agent and temperature, and the extraction rate of SiO2 by NaOH increases rapidly with the time expanding while that of Al2O3 falls gradually.

Jan 1, 2014

By Y. L. Tian

Low-grade bauxite with A/S of 4.4 from Henan province was used as raw material and the selec-tive grinding of bauxite, grinding efficiency, particle size and Al2O3 and SiO2distributions of ground products were investigated using ball and vibration mills. The results show that the selective grinding can be used to realize the separation of aluminum from silicon within a certain particle size. The optimal grinding conditions of the ball mill with bauxite are as follows: grinding material to charge ratio, 1.2, charge volume ratio, 40%, pulp con-centration, 70wt%, medium size distribution, F30mm:F20mm:F15mm=20%:50%:30%. Under the conditions, the weight rate of ground product with A/S over 7.5 is 27% and the recovery of Al 2O3is 30%. The optimal grinding condition of the vibration mill with bauxite are as follows: grinding material to charge ratio, 0.9; charge volume ratio, 70%; concentration, 70%; medium size distribution, F40mm:F30mm:F20mm=20%:30%:50%. Under the conditions, the weight ratio of ground product with A/S over 7.5 is 25% and the recovery of Al 2O3is 27%. The research is significant for the rational and economical utilization of the low-grade bauxite.

Jan 1, 2014

By V. I. Lakshmanan

The growing concerns on process efficiency, escalating operating and capital costs along with environmental and social concerns of using conventional technology for extracting gold and titanium dioxide demand an in-depth understanding of the fundamentals and a broader understanding of the various process steps involved. This will allow development of efficient process flowsheet for product recovery and compliance with regulatory guidelines. This paper will discuss our recent developments in mineral processing and hydrometallurgical technologies to recover gold and titanium dioxide from a wide range of feed materials including ores, concentrates and tailings.

Sep 1, 2012

By Liu Xinghua

Yuanjiacun iron ore located in Shanxi province of China has finely disseminated grain size and contains refractory iron-bearing silicate gangue minerals such as chlorite. Therefore, a large amount of secondary slime (the content of -10µm fraction was up to 32.92%) was produced inevitably in fine grinding process, and chlorite was also enriched in concentrate from the content of 4.3% to 14.8% after high intensity magnetic separation. These two characteristics result in the difficulty to deal with Yuanjiacun iron ore by flotation. In this test work, contrast tests between single reverse flotation and selective flocculation desliming-reverse flotation were conducted on Yuanjiacun iron ore. The test results show that after selective flocculation desliming, the iron grade of cationic reverse flotation concentrate increases by 6.15% and the recovery increases by 7.25%; the iron grade of anionic reverse flotation concentrate also increases by 2.15%. Furthermore, analyses of grain size composition and mineral composition were carried out on separation products, the results indicate that selective flocculation desliming plays a dual role of optimizing grain size composition of flotation feed and removing iron-bearing silicate gangue minerals (chlorite) effectively.

Sep 1, 2012

New technology for on-line particle size analysis of mineral slurries has opened up new applications for particle size measurement. In some cases the particle size distribution of the final concentrate is an important quality issue. This paper discusses established on-line particle size analysis technologies and presents experiences on the use of a new technique employing laser diffraction in several minerals processing operations. The main innovations in the new instrument are a simple dilution system and multiple scattering correction algorithm, which allows wide solids content variations of diluted sample in the measurement cell. Representative sample for laser measurement is produced by a simple and reliable dilution system. The applications discussed are; Blaine number measurement of Fe concentrate before pelletizing, grinding of variable batches of ore and paste thickener control.

Jan 1, 2014

By Graeme Lamson, Rene Dobbe, Merle Kalstrom, Janice Baron, Robert Thorpe, Chris Martin, Snezana Bajic, Amanda Palko

"This paper presents early results from a case study at the Mount Polley porphyry copper mine in British Columbia, Canada. Daily mineralogical data was acquired and reconciled with daily plant assay and recovery balances to interrogate the mineralogical controls on plant performance. After commissioning, the Minesite machine operated smoothly and reliably, creating daily data to generate mineralogical balances around the circuit for a period of several weeks. The key data, on final products were produced within 13 hours of the end of the respective operating period. The resulting information allowed for a greater understanding of the opportunities and limitations of the Mount Polley metallurgy. In this paper, how this information can be used to help long term strategic planning for the operation, as well as mine planning and production forecasting and the fine tuning of day to day mill operations is described. Early data available at the time of preparing this paper indicated that roughly 40% of the sulphide losses, or 32% of total copper losses existed as low grade inclusions in +75 micron tails. This represented the dominant form of long term copper losses, demonstrated repeatedly in the routine analytical data. However, on a day-to-day basis, the amount of copper present as chrysocolla is the major driver behind variations in total copper recovery. The degree to which this influences mill recovery is valuable to the geologist or mine planner. As they are armed with mineral speciation information for future ores, this will allow for improved mine planning, prediction of copper recoveries and production forecasting. The data was also started to find value in the mill by showing what caused sulphide losses. In the roughers, for example, the data showed poor recovery was the result of poor flotation performance and not any changes the speciation of copper sulphides or their liberation characteristics."

Jan 1, 2014

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

Domestic production of pyrite cinder reached 15.95 million tons in 2006. The pyrite cinder used in cement industry accounts for about 30% production. The remaining 70%, 11.17 million tons, was thrown away as waste, which brought serious environmental and resource problems. A new technology of composite pellet reduction-roasting and magnetic-separation (CPRM) has been developed to utilize pyrite cinder. Pyrite cinder sample, containing 45.56% Fe, 0.19% Cu and 1.45% S, was pelletized with addition of 5% composite agent in balling disc. Green balls after drying were reduced at 700~800 ? for 20min with 300kg/t pulverized coal injection in rotary kiln. After two stages of ball-grinding and four stages of magnetic separation, high grade magnetite concentrate with 66.23% Fe was produced, meanwhile impurities Cu and S was decreased to 0.048% and 0.053%, respectively. And iron recovery of 73.32%, desulphurization of 96.34% and decoppering degree of 74.73% were achieved. Key technique is that composite agent can accelerate reduction of Fe2O3 and transfer copper and sulphur into water-soluble inorganic salts, which can be removed during wet magnetic concentration. This new technology can be used to fully utilize pyrite cinder and produce high quality magnetite concentrates as feed for steel industry, which will help tackle the pollution problem of pyrite cinder and extend iron-bearing raw material sourcing for Chinese steel industry.

Jan 1, 2014

By B. Das

The separation of iron values from a typical Indian iron ore slimes containing 57.2% Fe, 5.81% SiO2 and 7.05% Al2O3 by wet magnetic separation and selective magnetic coating is investigated. The iron phases, which are mostly paramagnetic in nature, have been coated with magnetite or colloidal magnetite in presence of surfactant by manipulating the surface properties of the minerals. The studies have indicated that an iron concentrate containing 62.32% Fe with 66.5% iron recovery can be obtained at medium magnetic intensity of 7.8 kG which is much less compared to normal magnetic intensity of 13 kG to14 kG required for hematite-goethite separation. The performance of this technique with respect to both grade and recovery is superior to conventional magnetic separation or flotation of iron ore slimes.

Jan 1, 2014

This article takes the OMRON C200HE PLC for example introducing its application in mica-paper production equipment, including style selection, address assignment of I/O point, and programming for different function. In the transformation process of simulated data and digit data, the corresponding relations between two data and so on are also discussed.

Jan 1, 2014

By G. Aguilera

It is known that an addition of rigid particles into a fluid medium changes the flow field. Therefore, the rheological behavior of suspensions will be hardly Newtonian, such as their continuum phase. This phenomena was studied by Einstein in 1906 (Einstein, 1956) for the single case of spherical particles in a continuum liquid of a very dilute suspension. The final analysis applied for suspensions was derived from the evaluation of the behavior of ideal gases, finding a simple expression for the viscosity of the dispersion. All the following works about the hydrodynamics of suspensions at low and high solid contents was based in the Einstein´s model. For clay minerals suspensions where the physical and chemical properties of the particles are complex, it was found that the Einstein´s model is not a good approximation, even so for the most dilute dispersions. The present paper shows a new approximation that describes the non-Newtonian behavior of the suspensions of clays, and the attempt of understand how the different fine sizes, shapes and physico-chemical properties of clay particle surfaces give specific characteristics of plasticity, viscosity or visco elasticity to suspensions. Keywords: viscosity, clay minerals, einstein´s model, dilute suspensions

Sep 1, 2012