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By R. J. Batterham

The science and practice of mineral processing has been driven for many years by the same set of challenges that shape the mining industry ? demand and supply, grades and their decline with time, mineralogy and the need to handle more complex ores, disposal and minimising of wastes and the availability of water, power, skilled labour and the like together with increasing expectations from the community, concerns on sustainability and safety and, as well, climate change forcing a more targeted approach on energy. In this paper, the author builds on previous reviews to the IMPC and suggests that while step changes are long overdue, the unprecedented demand mitigates against drastic changes. That said, the ?Mine of the Future? is already requiring some different approaches.

Jan 1, 2014

By Agnieszka Surowiak, Tomasz Niedoba

The paper presents a way of determining relations between ash content in coal, particle size and particle density by means of regression, multidimensional Morgenstern distribution functions and kernel approximation. The three-dimensional random vector (D, ?, ?), where D is a random variable describing particle size, ? - random variable describing particle density and ? - random variable describing ash content, where function ?=?(d, ?) is obtained by means of regressive function. The multidimensional Morgenstern distribution functions and kernel estimators with the use of Gauss function were applied to approximate the functions f(d, ?, ?) and f1(d, ?). This approach is a new way of multidimensional description of grained materials such as coal and it also allows to evaluate material features more properly than the classical statistical approach. The results were verified statistically.

Jan 1, 2014

By Tomasz Niedoba

Coals occurring in nature are characterized by various properties. According to Polish norms, the classification of coals taking into consideration their calorific value contains coals from type 31 (flaming coal) until type 43 (meta-anthracite). The samples of coal of type 31 were taken for investigation. To this purpose, the approximations of ash contents and density distribution functions were done for this coal type (determination of marginal distribution functions). They were the basis for application of so-called Morgenstern distribution functions to approximate the function Z=L (?), where Z is ash contents and ? - coal density. Then, the comparison between obtained results was performed and the results were statistically evaluated. They are the basis for the further research of other types of coals.

Sep 1, 2012

By Hong Nguen Vu, Pavla Ovcarí, Peter Fecko, Barbara Tora

"The goal of the work was verification of bacterial leaching on the samples of black coal. From the results obtained it was clear that the coal is very well leached by Thiobacillus ferrooxidans and this technology can be used for coal desulphurization. A leaching time of one month is required, to remove 65% of total sulphur and 85% of pyritic sulphur.Microscopic evaluation of samples from Jaworzno showed, that it should be classed as a coal with low coalification, probably from black coal hemiphase. Macerals of the liptinite group were well distinguishable; they were of a dark brown colour. Evidence of coal mass oxidation was apparent on the fresh sample; in the test samples (during bacterial leaching) small grains were oxidised."

Jan 1, 2003

By R. Peter King, Claudio L. Schneider, Reiner Neumann

Predicting the liberation spectra that is produced from breakage of two-phase ores under the random fracture assumption can be accomplished by measuring the conditional, on length, linear grade distribution directly from images obtained from a representative sample of the unbroken texture. The technique tremendously simplifies the prediction problem by avoiding the multiple convolutions that arise from the traditional method based on a description of texture from a measurement of the chord length distributions associated with each phase in the unbroken texture. For a 3-phase system, the phase transition probabilities associated with the textural information make the traditional calculation an almost insurmountable mathematical problem. The direct measurement procedure on the other hand can be expanded to three phases comparatively easily.

Jan 1, 2003

By Jia Muxin

The adsorption behaviors of metal ions on a silicate mineral and the flotability of a metalized silicate mineral with sodium oleate as collector are closely related to the structure of the silicate mineral. The adsorption isothermals of the metal ions on different silicate minerals are studied, the parameters of the isothermal give the information how many surface oxygen anions a metal ions is attached to, from this information and the structure of the mineral the site where a metal ion is attached can be guessed (The adsorption isothermals and adsorption behaviors with pH are fitted with Temkin, Frenudlich and Kurbatov equations respectively). Metal ions as Cu2+, Ni2+, Zn2+ are attached to the oxygen anions of surface species –Si-O– on the quartz surface, most of them coordinate to only one surface oxygen, their adsorption ability on quartz is low, but this metal ions on quartz surface protrude out of the surface perfectly, so their ability to combine with oleate acid radical is excellent. Quartz can be activated well by such metal ions. The isothermal of Fe3+ on quartz indicates these cations coordinates with more than two surface oxygen anions. This means the Fe3+ nucleates on quartz surface in the form of Fe(OH)3 colloid particles. The isothermals of Cu2+, Ni2+, Zn2+ Fe3+ on spodumene shows such ions coordinate with more than two surface oxygen anions, it indicate these ions may attach to the position where Li+ is formerly exists, such metal ions stay in a cave on the mineral surface, their adsorption abilities on spodumene are quite well, but they are affect by the oxygen anions of the two Si tetrahedron chains, the can almost not activate this mineral. These cations may attach on the site where Al3+ exists on the muscovite surface, just like spodumene, muscovite can not be activated well by such cations. Pt2+ has a large ion radius, as Pauling’s rules depicts polyhedron can not attach to Si tetrahedron well, the adsorption ability of Pt2+ on quartz is low and quartz is activated badly by Pt2+. On the other Pt2+ can adsorb well on spodumene and muscovite well and activated them well because it is not affected so bad by the tetrahedron oxygen anions of the minerals for their its large radius. The isothermal of Ca2+ on quartz indicates a Ca2+ coordinates with less than one surface oxygen anion, this means Ca2+ attaches on quartz mainly by physical adsorption. The adsorption abilities on mineral surface and the interaction abilities with oleate acid radical of the transition metal ions with the same valence are guessed to be determined by their d electron number, the rules should be d1<d2<d3<d4>d5<d6<d7<d8<d9>d10. Hydrogen bond may play an important rule in the activation of the mineral by HF and the interaction of the HF activated silicate mineral with collectors. The general rule is high bond valence and small metal ion radius surface species –Me-O can be activated well by HF with sodium oleate as collector. For example – SiIV-OH is neutral while –SiIV-FH+ and –SiVI-FH+0.33 are positively charged, the positively charged surface species are more likely to connect oleate acid radical via hydrogen bonds.

Jan 1, 2003

By Abhilash

Different methods of utilizing refractory bauxite and disposing red mud are practiced throughout the world, but none of them are known to be environmentally innocuous due to the complexity and /or high cost, and none has been found to be feasible on an industrial scale. Under these conditions, the use of bioleaching process seems promising. The present study emphasizes on the isolation of native extremophiles from the source Indian bauxite and red mud, with their detailed cellular and physio-chemical, and biochemical characterization. These organisms were tested for their ability to thrive in physically or geochemically extreme conditions. The gram positive capsule rich mesophiles and thermophiles were tested for removal of gangue minerals from the bauxite and red mud samples. Keywords: refractory bauxite, red mud, extremophiles, bio-beneficiation, gangue

Sep 1, 2012

By Z. F. Hu

Tourmaline has the characteristics of piezoelectricity, thermoelectricity, spontaneous polarization and far-off infrared radiations. Ultra-fine powders of tourmaline have extensive applications in the fields of electron, chemical and environment protection, as well as health protection. The preparation technology of ultra-fine tourmaline powder is discussed. The key equipment of a pilot plant for producing ultra-fine tourmaline powder with jet mill and stirred ball mill is described. Using this pilot plant facility it is possible to produce tourmaline powder with particle size smaller than 100 nm, and a continuous production process can be realized. The final powder product has many superior performance such as high whiteness and large specific surface area, and it?s a negative ions emission can reach the value of 7190 ions per cubic centimeter.

Jan 1, 2014

By Carin Laubscher, Francis W. Petersen, Jaap P. Smit

"Waste streams, such as acid mine drainage, are often characterised by low pH values and high concentrations of heavy metals, dissolved solids, calcium and sulphates. Although lime remediation effectively removes most of the heavy metals as hydroxides, it is less effective at lowering levels of sulphates. Various methods of removing sulphates from effluents exist, such as precipitation with lime, precipitation with barium salts, co-precipitation with calcium carbonate, reverse osmosis, and ion exchange. Mintek developed a chemical precipitation (SAVMIN) process to treat acid mine drainage, which entails the addition of lime to precipitate the metal hydroxides, and the subsequent formation (precipitation) of calcium sulphoaluminate or ettringite. The key to the viability of the new technology lies in the correct use, regeneration and recycling of Al(OH)3 used to precipitate the ettringite. The water produced by this process is suitable for disposal to watercourses or for agricultural, domestic or industrial consumption. No brines are produced as the salts are converted to solid hydroxides, gypsum and calcium carbonate.The SAVMIN process has been tested successfully during several laboratory scale operations, and during two pilot plant operations at Stilfontein Goldmine for Anglogold and Navigation Plant, Witbank for Anglocoal. During the pilot plant campaign at Navigation Plant, metal and mineral precipitation was achieved with lime addition. The sulphate concentration in the water was reduced from 2136 mg/L to an average value of 102 mg/L and the calcium concentration was reduced from 727 mg/L to an average value of 70mg/L.The SAVMIN process generates a number of different waste streams including metal hydroxide sludge from neutralisation, gypsum sludge from the gypsum crystallisation steps, and calcite sludge from carbonation. The metal hydroxide sludge is composed of Mg, Ca, Mn and Fe hydroxide, and could be disposed of on a slimes dam. Gypsum sludge was greater than 99% CaSO4.2H2O. This gypsum could be used for dump or road capping, underground backfilling, production of wallboard and cement. The calcite sludge is pure CaCO3, which is recycled back to the neutralisation stage."

Jan 1, 2003

By Markus A. Reuter, Antoinette van Schaik

"INTRODUCTIONGoods and products, such as passenger vehicles, are manufactured by using a wide spectrum of different raw materials to meet highest consumer requirements during use. Due to the time-varying composition and complexity of multi-component products such as cars, recycling is complicated. It involves a network of interconnected processes and material and energy flows. Improving the efficiency of the material cycle of the car to comply with the recycling targets as imposed by EU legislation, requires insight into all aspects influencing the closing of the material cycle (dynamics, technology, economy, legislation, etc.) and their mutual relation. In order to define the link between recycling end-of-life products, their changing composition and design a dynamic model was developed for the resource cycle of cars. The model integrates the optimisation of the material cycle with the dynamic behaviour of recycling systems."

Jan 1, 2003

By Leon Lorenzen, Nursen Guresin, Harald Muller

The development of mining projects from discovery, exploration to actual production is a complex and time consuming process. Often poor process plant performance can be attributed to the use of non-representative samples and inadequate and/or unsuitable metallurgical test work when designing flow sheets during project feasibility study stages and specifying process equipment. Samples not representing the ore deposit and inadequate test work may lead to increased project development costs, since expensive test work and engineering may have to be repeated. It should be noted that for higher level engineering studies, larger scale test work is recommended and is a requirement for feasibility level studies. This would apply even if the technology is considered mature and well proven, as each ore body may have its own unique characteristics that, if untested at a larger scale, could result in significant design shortcomings, which will have to be rectified at later stages of the project, usually at significant additional costs

Jan 1, 2014

By Georg Unland, Thomas Wegner

"Different types of impact crushers use the physical effect of impact to crush rocks. The rocks can vary from soft to hard and from ductile to brittle but they should never be abrasive. Since the principles of impact crushing of larger rocks are hardly investigated these crushers are still sized rather by empirical than by scientific approaches.In order to investigate the principles of comminution by impact of large rocks a test rotor was developed and rocks of different dimensions were tested. The integrated measuring devices of the rotor enable the recording of impact forces and of absorbed impact energy with high resolution during the contact time.Since impact crushers stress the rock particles with a defined velocity the main crushing properties are gained as a function of the applied velocity and the particle size of the rock: likelihood of breakage, contact time, maximum crushing force, mass specific crushing work, surface related crushing ratio and crushed fragment shape distribution."

Jan 1, 2003

By C. Eswaraiah

A drop weight tester (DWT) is designed and fabricated for the purpose of analyzing single particle impact breakage characteristics of different ores. The test results were evaluated through the breakage distributions of different size fractions at five different input energy levels. The breakage parameter, t10 (Narayanan, 1986) is used to represent the degree of size reduction, which is assumed to be representative of the breakage product size distribution obtained from single particle breakage. Representation of breakage distribution with this method consist one more breakage dependent parameter (a). To evaluate the impact breakage characteristic of different ores, a mathematical relationship was established to analyze the dependency of breakage parameters, t10 and a on specific input energy (EIS) or fracture energy (Tavares et al, 1998, Fandrich, 1998), specimen size (?) and Bond?s operating work index (WI0). Mathematical results developed gives adequate model for all ball mill modeling. It can be concluded that the drop weight test method is a useful and practical way of evaluating the impact strengths of various ores and results of which can be used in modeling mills.

Sep 1, 2012

By S. H. Shahcheraghi

The four operational parameters including collector dosage, frother dosage, conditioning time and pH, are the most important parameters effective on the flotation kinetic. The present study has been done at the Miduk Copper Complex in the province of Kerman. The effect of operational parameters on the flotation kinetic of copper minerals were studied and analyzed, so the optimum conditions for flotation kinetic of copper sulfide minerals were obtained. Under the obtained optimum operational conditions, the recovery of copper sulfide flotation at the 95% confidence level was estimated to be between 92.76% and 95.48% and the copper sulfide flotation kinetic constant was estimated to be between 1.40 and 1.45 min-1. Results showed that the consumption of the X231 collector (O-isopropyl-N-ethylthionocarbamate) and the A65 frother (Polypropylene glycol) could decrease up to 35% and 50% respectively while the copper sulfide recovery increases about 1 up to 2% at the laboratory scale. Keywords: flotation kinetics, sulfide copper, optimization, the Miduk Copper Complex, response surface method

Sep 1, 2012

By M. Ito

Cobalt-rich ferromanganese crust and nodule ores from seamount areas contain volcanic and sedimentary rocks as substrate or nuclei. These ores require mineral processing to remove the sub-strate/nuclei rock before smelting. This paper reviews experimental results of previous investigations. Observations and analysis of 10 samples from different localities were carried out and it was found that the liberation ratio of crushed product was high even at coarse size fraction, 0.5mm to 4mm. Experimental and calculated results in the smelting stage confirmed that the separation product satisfies the standards of the subsequent smelting process if the substrate/nuclei rock is removed from the 0.5mm to 4mm fraction with high separation efficiency. There was a density difference between the substrate/nuclei rock and the ferromanganese component. Thus the coarse sized sample was treated with gravity separation; air table separation was used as a dry method and jig separation as a wet method and high grade values with high recoveries were obtained by both kinds of gravity separation.

Jan 1, 2014

By R. K. Rath

The low-grade iron ore sample contains both lumps and fines. It is mostly hematitic iron ore and considerable amount of goethitic/limonitic material is present in it. The major impurities present were quartz and clay. It is observed that the iron bearing phases are poorly liberated above 300 µm and the liberation improves below 300 µm. More than 80% liberation is achieved below 106 µm. Based on the liberation data, the feed for the different beneficiation methods was prepared by stage crushed the ROM followed by grinding passing to 106µm and the ground material (-106µm) was deslimed. The underflow was subjected to various beneficiation techniques such as tabling, enhanced gravity separator (EGS), wet high intensity magnetic separation (WHIMS), and flotation and the results are discussed. All the methods studied could able to produce pellet grade concentrate with iron content of 64.5%, however, a marginal higher yield was observed for WHIMS (81%). Keywords: beneficiation, gravity, magnetic, enhanced gravity separation, flotation, low-grade iron ore, desliming

Sep 1, 2012

By Bisweswar Das, Barada Mishra, Hrushikesh Sahoo, Swagat Rath

Banded hematite jasper (BHJ) containing 45.2% Fe, 32.64% SiO2, 0.63 % Al2O3 and 1.25 % LOI is found difficult to beneficiate either by magnetic or flotation techniques due to fine intergrowth of jasper with hematite. Phase transformation by reduction roasting with activated charcoal followed by low intensity magnetic separation to achieve a suitable iron concentrate has been attempted in this study. The mineralogy of the ore and different roasted products has been studied by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) to understand the reduction mechanism. The magnetite formation is observed at 850ºC while metallic iron appeared at a higher temperature. The effects of reduction variables such as reduction time (30-270 min), temperature (750-1050ºC), and reductant (1-12 %) using activated charcoal are studied. An iron concentrate with 64.65% Fe and 55.8% recovery could be obtained under optimum conditions of temperature: 850ºC, time: 1.5 h, and reductant: 6% by weight.

Jan 1, 2014

By F. Z. Dong

The paper is mainly about a study on the techniques of separating iron from pyrite cinder of a certain sulfuric acid plant in Shandong province. The main components of the cinder are Fe2O3 and SiO2, and the degree of liberation of iron mineral and gangue is very high. So the iron concentrate with higher degree of iron and lower grade of silicon and sulfur can be achieved by reverse flotation. The iron grade of the concentrate reaches 63% and the recovery of iron is no less than 63%. And the most important influencing factor of the flotation is the temperature of the pulp. A better guideline can be achieved by magnetic separation. The cinder is magnetizing roasted for 15 minutes with temperature of 800?, and the concentrate with the iron grade 64%, sulfur grade 0.2% and iron recovery 85% can be obtained by two stage magnetic separation. A rotary kiln has been built to deal with the pyrite cinder, and the result of the industrial magnetizing experiment and magnetic separation is satisfying.

Jan 1, 2014

By C. Çelik

Nowadays the optical sorting of industrial minerals is one of the most important processing methods which has cost efficient production possibilities. This method is used for industrial and raw materials that have different colour and brightness features. Initially this technology is used for sorting of foodstuffs and recovered glass, but for a long time also as physical mineral processing method for both industrial minerals like: limestone, marble, talc, basalt, flint, quartz and secondary raw materials like: building rubble, refractory materials, glass, plastic and household waste. In this study via optical sorting the separation of quartz out of a flint mix, which consists of the particles with different colors and brightness, is aimed. Experiments are performed on an optical sorting machine named CombiSense® 1200 at the institute of ?Aufbereitung mineralischer Rohs-toffe? RWTH Aachen. This automatic picking device was developed by the company ?Separation Systems Engineering (SSE), Wedel?. Hand picking method is used for product analysis and the efficiency tables are prepared on every step accordingly. This process enables to reach quartz products with purity up to 100%.

Jan 1, 2014

By A. C. Maffei, M. V. Lins Gonçalves

Ore concentration processes are a function of the respective particle size distribution; however, most of them do not use an efficient operational method to determine it. From a practical point of view, the surface area can be calculated for any size analysis. The physical principles for determining the size distribution in each method are different, for the results will not be compared directly. During the development of the research project of the sulfide ore flotation method using inert gas, different methods for calculating the specific surface area have been used, such as sieving, sedimentation/X-ray, laser diffraction and BET, i.e. specific techniques to determine the specific surface area of copper and gold ore concentrates. The statistical method of minimum squares was used to achieve practical correlation equations among them. Regarding these two ores, if one knows a specific surface area value using one of the methods above, one can predict the result of the others. Diminution of the reagent consumption was so controlled and it could be even decreased by using inert gas.

Jan 1, 2003