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By Sergey Ulianov, Arkady Senchenko, Alexey Shvets, Arkady Bakotin

"This paper is devoted to ultrafine grinding of processing products. This process allows one to include into operation complex ores which earlier were considered as inefficient and economically inadvisable to treat. Fine dissemination of valuable component often does not allow its liberation via standard grinding in ball mills, and therefore requires modern methods of ultrafine grinding (UFG). An example of successful ultrafine grinding usage is its application for crude flotation concentrates regrinding before cleaner flotation stages. A problem often arises with a commercial copper concentrate production in the course of copper ore flotation. Crude flotation concentrate regrinding in a ball mill does not provide for good liberation of the material before cleaner stages. UFG application allows one to get commercial copper concentrate with copper grade of 20% and higher. Another example of ultrafine grinding application is its usage for highly refractory pyrite product received after gold-lead scavenger flotation of polymetallic ore. Earlier this product treatment was economically inefficient. At current application of ultrafine grinding down to 85% minus 20 µm and subsequent gravity processing it is possible to pass major part of gold (73.4%) into concentrate. The constraining factor for UFG application in processing may be the chemical activation of minerals. In the result of this, flotation selectivity may decrease. Therefore ultrafine grinding application extends the areas of efficient usage of metallurgical processes. New technologies allow increasing the level of valuable metals recovery."

Jan 1, 2014

By Li Maolin, Cui Rui, Wang Guanghui

"As the stirrer speed directly affects the motion of grinding media, and hence the interactions with material particles to be ground, the rotation speed of a stirred mill is well recognized as one of the most important factors affecting the grinding performance. In this work, the effect of stirrer speed on grinding performance in terms of grinding rate and grinding energy efficiency was quantitatively investigated. Batch wet grinding tests of quartz powder at different stirrer speeds were performed, using a self-made horizontal stirred mill with alumina balls as grinding media. Grinding time, operating power and the sizes of ground product were recorded to analyse the grinding performance. The test results showed that grinding processes followed the first order grinding kinetics. The grinding rate constant increased with the increasing stirrer speed. Based on the grinding kinetics, the grinding energy equation was established. The energy utilization coefficient in the energy equation can be used as an indicator of energy efficiency. The energy efficiency decreased with the increasing stirrer speed. Quantitatively, with the stirrer tip speed increasing from 4.25m/s to 9.35m/s, the grinding rate constant was improved by 441.47%, whereas the energy utilization coefficient was decreased by 39.35%. The grinding rate constant and energy utilization coefficient can be used to evaluate the grinding performance when the grinding conditions need to be adjusted. The adjustment of grinding conditons would be optimal when grinding rate get significant improved with little decrease of energy efficiency."

Jan 1, 2014

By P. Banerjee, P. Dash, S. Sriramoju, A. Suresh, R. Lingam, T. Ray

"One single property that influences the quality and market value of coal to the maximum extent is the ash content. The lower the coal ash higher is the energy utilization and potential for different applications. Even though Indian coal washeries aspire to produce coal with low ash, the intimate distribution pattern of ash bearing minerals in the coal matrix becomes the real bottleneck, as it brings down the clean coal yield to the impractical value. Because of this fact, most of the Indian washeries are operated to produce coal with 14-15% ash content at the yield of around 40%. In this context, with an objective to produce low ash coal at higher yield, a novel chemical beneficiation route has been explored to demineralize the high ash containing Indian coals. In this present work, the production of low ash clean coal from high ash Indian coals using chemical leaching process has been studied at pilot plant level. The leaching process parameters such as reaction temperature, reagent concentration, reaction time, coal-liquid ratio and agitator speed have been optimized for the flotation tailings sample from a captive washery of Tata Steel. The results obtained show that 67% demineralization could be achieved in a single stage of leaching process with a product yield of more than 65%. For further demineralization, multistage leaching was carried out and the results showed that 75-85% demineralization could be achieved with significant reduction in alumina to silica ratio. Additionally, the phosphorus content is also significantly reduced from 0.20 % to 0.022 %. Further, it is interesting to note that there is no increment of sodium content in the product coal after chemical treatment."

Jan 1, 2014

By Joseph Kelly, Christopher Kelsey

This revolutionary super-fine crusher has the unique capacity to generate fine and ultra-fine products from single stage reductions of coarse or fine mineral feeds. The crusher consists of a rotating compression chamber and an internal gyrating mandrel. The axis of rotation of the shell is displaced relative to the axis of the vertically mounted mandrel. The inner surface of the compression chamber is machined as double cone frustums at an angle equal to the displacement angle. Crusher feed is accelerated into a compacted particle bed, which lines the inside of the compression chamber. The depth of the compacted bed progressively increases until the mandrel is engaged. The mandrel is then free to rotate with the compression chamber. Continued feeding increases power draw and triggers the counter rotating mandrel gyration drive. The gyrating mandrel delivers multiple compressions at high pressure to the rotating particle bed. High concentrations of energy are harnessed within a small active volume over short retention times. The combination of extraordinarily high power intensity and extreme compressive force results in primary compressive fracture and induced secondary tensile failure. The axially displaced rotation of the compression chamber effectively distributes the breakage forces throughout the particle bed. This paper covers open circuit, pilot trials on magnetite, perlite, garnet, marble and a copper/pyrite concentrate. Particular emphasis is placed on the extraordinary results achieved with trials on zircon and highly refractory fly ash. The extreme duties were deliberately chosen to demonstrate the crusher’s application scope and potential to impact capital operating and maintenance costs as the technology matures. Super-fine crushing, once considered impracticable has the potential to offer compelling options for the generation of ultra-fine products.

Jan 1, 2014

By Gülay Bulut, Ferihan Göktepe

Pyrite is the most abundant and widespread sulphide mineral and its flotation has been investigated by many researchers. It is well known that, pyrite is floatable under acidic conditions and recovery drops with increase in alkalinity due to changes in solubility of iron hydroxides on the pyrite surface. Most of the works also revealed out that pyrite displays variable behaviour in flotation circuits. This behaviour mainly related with origin and mineralogical composition of ore, liberation size, electrochemical behavior of minerals constituting ore, the trace and minor element content of the mineral, texture, application variables belonging to flotation circuits. In this study, copper activation effect was examined on different origin of pyrites. The experiments were performed with five high grade samples of pyrite from the different mining districts of Turkey. The pyrite samples were different from each other with respect to either their physical or chemical properties; they were different physical appearances and contained different associated minerals. In the micro-flotation tests, 1x10-4 mole/L copper sulphate and 1x10-4 potassium ethyl xanthate were used as flotation reagents. First of all pyrite samples were floated using only xanthate at different pH. Results showed that best floatation results obtained at acidic pH range for all pyrite samples. When copper ions were used to activate, all pyrite samples floated at neutral and basic pH values, too but depending on the samples, recovery and pH ranges were slightly changed.

Jan 1, 2014

By Muammer Kaya, Sait Kursunoglu

"Energy is the major concern for society. It is expected that developing country economies and populations will grow and consume more energy. Interest in nuclear power is rising, while the world looks for non-depletable energy source that will not contribute to global warming. However, it still has concerns of nuclear proliferation, radioactive waste and safety. It is necessary to overcome these concerns if nuclear energy is expanded to developing countries. Thorium (Th) utilization as nuclear fuel will be an opening key of these difficulties because Th produces less Plutonium (Pu) and less radioactive waste with enhanced safety. Research into the use of Th as a nuclear fuel has been taking place over forty years, through with much less intensity than that for uranium (U) or U-Pu fuels. Nuclear industry is currently using only 0.7% of the available energy from mined U. With huge resources of Th and relatively little U, Turkey has made utilization of Th for large-scale energy production a major goal in its nuclear power programme. Thorium fuel is plentiful and inexpensive. Energy is major concern for developing Turkish society. Turkey, today exports more than 70% of its energy as fossil fuels. In the last 50 years, Turks are skeptical, anxious and indecisive about having nuclear energy for electricity production. In the last 10 years, Thorium is brought into Turkish government’s attention and national discussion as a new, safe, clean, affordable, CO2-free, alternative, strategic and domestic nuclear energy fuel. Turkey recently contacted four VVER-1200 type Russian Nuclear Power Reactors using U as a fuel in Akkuyu (Rosatom) and another four units will be established in Sinop in the next decade by Japan (Mitsubishi-Westinghouse). Turkish nuclear programme must envisage use of domestic Th as a fertile material. This paper briefly reviews the developments of Th-fuel cycle for nuclear energy from global and Turkish perspectives. Previous Th reserve development and recovery studies from Turkish bastnasite ore are summarized in this paper."

Jan 1, 2014

By Nicolus Rotich, Ritva Tuunila, Louhi-Kultanen. Marjatta

Most minerals, their ores, and gangue require sorting in order to maximize the recovery of the primary product during concentration. Gravity separation though old, is not obsolete and is continually playing an important role in mineral processing and many other industries, especially where plant energy efficiency is of concern. Screen designs e.g. material of construction, deck angle of inclination, the feed throughput, and physical as well as chemical properties of the particles, are critical factors to consider when using gravity for solid separation. Solids loading and screen geometry are significant, and easily manipulated operational parameters that affect both the screening rate and efficiency to a large extent. In this paper we applied nonlinear least squares optimization technique, and response surface methodology first, to assess the significance of the two factors, and secondly to select the best mathematical models that optimize both capacity and efficiency of the screening process. Initial experiments and confirmation tests were conducted on a prototype screen of 846.51cm2 effective area, (2100 cm2 total area). For glass beads of sizes 0.75-3mm, with feed loads of 10g up to 160g, and inclination angles from 5-20o, a maximum efficiency of 66.7%, and a screening rate of 22g/s was achieved with a screen loading of 86.5g, and an inclination angle of 12.43o. These results were then subjected to nonlinear least squares optimization, in which afterwards an optimum theoretical efficiency of 72% and screening rate of 31.2g/s were achieved at a loading of up to 104g. There was excellent performance at angles 12.5=?=17.5, but poor at the angles outside this range. The screening efficiency did not seem to respond significantly to changes in screen loading. Confirmation tests conducted at selected optimum parameters achieved an efficiency of 72.1% (at 17.5o with 88g load), and a rate of 27g/s at 16.5o with 104g.

Jan 1, 2014

By G. N. Jadhav

In India, bauxite deposits are concentrated in Central India, Western Ghats and Eastern Ghats. Bauxites from various regions in Gujarat were identified during the present investigations of geochemical mapping. Different types of Bauxites samples were collected from Kachchh, Jamnagar, Porbunder, Junagarh, Bhavnagar and Amreli areas of Gujarat state and were studied in detail for their geochemical signatures to plot the data on Geochemical map. Raw bauxites were characterized by using powder XRD, XRF, ICP and optical microscopy techniques (with the help of Model microscope having both transmitted and reflected light setups) and were later examined to grade their quality. Most of the bauxites from Kachchh region were of high-grade (gibbsitic) type; while those of Sourashtra region were of low-grade (lateritic / calcitic) types. Most of these bauxites were either of ferruginous/lateritic or of calcareous/calcitic types. Based on the mineralogical composition, such as gibbsite, hematite and/or goethite, Kaolinite and calcite minerals present in particular bauxites, the deposits were graded. Finally, the Geochemical mapping of Bauxites for Gujarat region was prepared and discussed.

Sep 1, 2012

By D. B. Sundar Ramam

In the recent past, a paradigm shift in terms of resource utilization and beneficiation practices is experienced by the Indian mining and mineral sector. Depleting iron ore reserves coupled with increasing demand for low-alumina iron ore fines to improve blast furnace performance in terms of productivity and reduced slag rate necessitate intensive beneficiation of iron ore. The task is even difficult for Indian iron ores, which are generally high in iron content and at the same time characterized by aluminous gangue. In 2006, M/s Tata Steel commissioned a state-of-the-art Jigging Plant (Batac Jig) at Noamundi Iron Mine (NIM), mainly to reduce alumina in iron ore fines. The jigging plant is incorporated in the existing beneficiation circuit to treat ?10+0.5mm size fraction of classifier fines. Over the course of plant stabilization while the plant could deliver desired ore upgradation and average product alumina, variability in terms of alumina content has been a concern. This paper discusses a case study of process parameters optimization in jigging operation to achieve consistent product quality while improving the effectiveness of gravity concentration for the beneficiation of Noamundi iron ore also to take care of inferior plant feed (input) grade year on year. The operating variables used to optimize jigging operations include bed height, pulsion and suction time, particle size, strokes, and plant throughput rate.

Sep 1, 2012

By A. V. Golovanov, A. V. Mihailova

"NPO RIVS employs complex approach to engineering and design of the new facilities in close cooperation of Mining, Research, Hydrometallurgy, Design, Construction, Power Supply, Automation, Production and other departments. General Design Contractor (and then General Contractor) is directly involved in geological exploration, engineering surveys, floatability studies, feasibility study of process solutions and construction options. It delivers greenfield project and guarantee its efficient performance in future. Shiralgin is a small gold and copper deposit, gold average grade is 4.7 g/t. RIVS departments have studied ore floatability, developed process procedures for design and performed pilot testing. Construction of integrated plant including ore crushing and grinding, flotation and hydrometallurgy units with Dore gold production of 5 000 thousand tons ore per year (66.7 t/h) is recognized as economically viable. The technology used of separate dry stockpiling of flotation tailings and cyanidation tailings. Water circuit for concentration and hydrometallurgy is separated, too. Process design was performed based on BIM software like Autodesk Revit, Civil 3D, Rocscience slide using process procedures developed by RIVS Research units. Engineers provided modeling of primary crushing unit, coarse ore storage, main building (including grinding, flotation, thickening, filtration, loading, hydrometallurgy), tailings thickening unit, building for reagent storage and conditioning, tailings pond for dry stockpiling of flotation tailings and cyanidation tailings, sedimentation ponds, laboratories, infrastructure including Administration building and camp. Payback period is 3.5 years. 3D model of facility is currently stored at the State Agency of Geology and Mineral Resources affiliated to the Government of the Kyrgyz Republic.INTRODUCTION The Kyrgyz Republic has substantial potential of mineral resources including gold ores. Mining industry actively develops and involves international investors. Inventory includes 42 deposits (Figure 1) that have reserves of 616.4 t [1] of gold. The Kyrgyz Republic takes the third place in gold mining among CIS countries after Russia and Uzbekistan by producing up to 20 t annually."

Jan 1, 2018

By Shi Shuaixing Zhang Yuejun, Fan Xuesai Zhangming

"For the traditional principle of flotation cell design, or in the perspective of some researchers, the mixing effect of impeller for flotation cell is not only to suspend the particles off the bottom, but also to mix slurry well to achieve a uniform system. But for some special processing conditions, the depth profile of slurry concentration and particle size demonstrates an obvious difference. In the part around of the impeller in the cell, the slurry concentration is much higher than the part below the lip.For the vanadium titano-magnetite flotation process, distinguished with high concentration and large coarse particle size fraction, even though the concentration is very high, it can reach good gas dispersion, which is a fundamental principle for flotation cell design and application. The gas dispersion is not a challenge in the high slurry concentration environment, not only in the vertical direction, but in the cross section. Different levels (the distance from the lip is 400mm, 700mm, 1200mm, 1700mm, 2200mm, 2700mm) slurry in the flotation cell is sampled and analyzed. The slurry concentration of the 3 levels(1700mm, 2200mm, 2700mm) is about 55%, but the slurry concentration decreases from 55% to 25% sharply towards the lip.Therefore, a new understanding and viewpoint is presented, that the uniform system of slurry is not always reasonable for all of the flotation process. For some special process, if the coarse particles are needed to agitated well and transported to the upper cell, the quiescent zone in the upper cell will be destroyed and enhance the detachment probability for the coarse particles. The difference of slurry concentration and particle size fraction benefits the air dispersion and coarse mineral particles recovery.1.INTRODUCTIONNowadays, flotation is the most widely used separation process in the mineral processing industry. The importance of flotation technology in the global economy is significant. A rough estimate of the quantity of crushed ore treated by flotation is about nine billion tons per year, and the portion of base metals processed using this method is approximately 95% (Brewis, 1996)."

Jan 1, 2018

By M. Amani, A. Akbarinasab, M. Bazmandeh

The fourth iron ore production plant at Golgohar mining and industrial company consists a ball mill and wet medium intensity magnetic separators (3500 Guss). The ball mill product applies directly into MIMS and the MIMS concentrate directly transfers to the low intensity magnet separators (LIMS). The thickener is used for dewatering of MIMS and LIMS tailings. By sampling from streams of ball mill and separators, it was defined that the grade and iron recovery were 60% and 80% respectively while they would be 66% and 90% respectively based on the designing documentation. The average of P80 in the ball mill was 342 micron in a month that is coarser than optimized value. This problem was related to unsuitable operation of grinding. For optimization of grinding efficiency, the amount of charge volume was investigated as a variable. The measurements illustrated 32% charge volume. For increasing grinding efficiency, the charge volume was increased 1% and 1.6% in two stages. The results showed ball mill power draw average reached from 3650 kw to 4120 kw and the average P80 reached to 329 micron. All of parameters calculated about 35 day before and after change. Average of Ball mill feed iron ore grade before and after change was 49.24% and 50.32% respectively. This change caused an increase in efficiency of MIMS, where the enrichment ratio and concentrate grade increased 2% and 1.9% respectively. For increasing the iron grade of the MIMS concentrate; the orifice of the tail flow exit pipe changed from 4 inch to 6 inch and the concentrate grade increased 2%.

Jan 1, 2014

By Andrey Kozlov

The results of mineralogical?technological studies of PGM mineralization in zoned mafic?ultramafic complexes of the Ural?Alaskan type are given. The most important technological specificity of PGM mineralization hosted in dunites is its occurrence only in the form of free mineral species with predominance of Fe?Pt alloys (ferrous platinum, isoferroplatinum, and tetraferroplatinum). Technological properties, grain size, and good opening of PGM ore in grain size class +80 µm make it possible to concentrate ore using gravity methods with stadial comminution and between cycle separation of relatively large grains and nuggets into high-grade concentrates at the early stage of disintegration. Keywords: platiniferous dunites, PGM mineralization, mineralogical?technological studies and processibility research, recovery technology, gravity methods

Sep 1, 2012

By V. V. Trusova, Shiyrav Gandandorzh, K. V. Fedotov, V. A. Domracheva

"In Russia, 1.1 million tons of mercury-containing waste are stored. The amount of mercury in soils and heaps of industrial enterprises is estimated at 3000 tons; in dumps, concentration tailings, sludge dumps of the gold mining industry up to 6000 tons have been accumulated. Mining is one of the main sources of mercury emissions in the natural environment that poses a real threat to the natural environment. At present, the process of amalgamation is prohibited and not applied in gold extraction. The application of amalgam technology in gold mining led to the accumulation of highly toxic products in the form of gold-bearing amalgam and metallic mercury, with a mercury content of dozens and even hundreds of times greater than the maximum permissible concentration for soil (1). Therefore, mercury-containing tailings constitute an ecological hazard to the environment. According to published data, at waste storage sites of industrial enterprises, up to 50 tons of mercury enter soil annually, and up to 3.5 tons pollute the air. At the same time, mercury-containing waste due to the reduction of the country's mineral resources is an additional source of mercury. Therefore, it is necessary to recycle mercury-containing waste. INTRODUCTION Paperobjective: demercurization of technogenic raw materials (amalgamation tails, discharge outlets of tailing dumps) to be recycled. Under natural conditions, the mercury usually migrates in the form of three most common compounds: elementary mercury (Hg); mercuric mercury ion (Hg+2); methylmercuryion (Hg (CH3) +. Chemical compounds Hg (II) are found in natural conditions much more often than Hg (I).The authors propose to conduct demercurization of technogenic raw materials (mercurial tailings) in two stages. At the first stage, the mercury in the form of small balls, the finest particles (drip mercury) can be extracted by applying the gravitational method. We propose a method for centrifugal processing of crushed waste in the apparatus of Itomak company, Novosibirsk, as the basis of the technological process for mercury recycling. The extraction of metallic mercury out of mercury-containing waste into commercial products, according to the technological characteristics of the Itomak apparatus, reaches 86.0% (2, 3). At the second stage, the extraction of mercury out of technogenic raw materials is performed applying a sorption method and using carbon sorbents based on fossil coals. Hard coal of the Kuznetsk Basin has been already used for industrial production of active carbons (carbon sorbents) of the KAD-iodine type, which is one of the prerequisites that determine the choice to use it for the aims of this study."

Jan 1, 2018

By S. Banisi, E. Arghavani, M. Pourkani, M. J. Rajabi, Gh. A. Mohamadian, H. Bidshahri, Gh. A. Parsapour

The Sarcheshmeh copper complex flotation circuit of plant No.1 consists of two identical north and south sections where each includes four rougher (each bank consists of 14 cells), two cleaners (each bank consists of 8 cells), two recleaners (each bank consists of 2 cells), and two scavenger banks (each bank consists of 10 cells). The reduction of feed grade along with a change in the mineralogical composition is the main reason of current lower concentrate grade (24%) compared with the design concentrate grade (32%). Because of a lower feed grade, the amount of rougher concentrate has decreased which in turn has significantly reduced the feed rate to the cleaner, recleaner, and scavenger banks. This has increased the mean residence time of the material in the cleaner section resulting in a lower final concentrate grade. A laboratory study showed that the final concentrate grade can be increased by 2-4% if one cleaner stage is added to the flotation circuit. In this research, based on the laboratory results, one cleaning stage was added to the current flotation circuit. In order to make this modification instrumentally possible in the plant, the final concentrate was gravity transported to the Mo-Cu thickeners. This released 2 pumps and associated tanks which made addition of one cleaning stage practicable. Finally, a part of the cleaner and scavenger cells were used as the third cleaning stage. This decreased the residence time in the cleaner and scavenger banks. After implementation of one cleaning stage in the south section of the plant, the performance of the circuit compared with the identical north section. It was found that at the same recovery, the concentrate grade of the south section increased by 2.5%. The promising results led to the implementation of adding one cleaning stage in all sections of the flotation circuit.

Jan 1, 2018

By A. I. Arol

Bentonite is an important industrial mineral with very wide application areas. Its unique colloidal, swelling, thickening and adsorption properties make it a useful agent in drilling, metal casting, and iron ore pelletizing, environmental, food, cosmetics, pharmaceuticals and many more industries. Because of its swelling property, bentonite suspensions can only be prepared at rather low solid coentrations, i.e. 8-10%. In order to process bentonite in slurries with high solid content, it was thought that a non-polar organic solvent, instead of water, can be used. Not only large amounts of bentonite can be dispersed in organic solvents but also the solvents may be regenerated. The bentonite obtained through such a process must either equal or better properties than those of untreated bentonite. In this study, the effect of organic solvents such as acetone, methyl-ethyl ketone and n-haxane on the main properties of bentonite, such as water adsorption and rheology, was investigated. It was found that bentonite can be dispersed in the mentioned organics in large quantities with no loss of quality. Keywords: bentonite, montmorillonite, water adsorption, industrial minerals

Sep 1, 2012

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 D. Vega, P. R. Brito-Parada

"Small diameter (10 mm) hydrocyclones have been applied successfully for the separation of particle suspensions in the micron size range. These hydrocyclones are attractive because they show a bypass fraction larger that the water recovery, resulting in a high particle recovery to the underflow as well as low water recovery. However, this is a disadvantage when the purpose of the hydrocyclone is classification because of the large amount of fine particles that are misplaced in the underflow. The aim of this study is to explore, experimentally and computationally, the influence of design parameters on the classification process. In this work, a full factorial experimental design was defined to carry out comprehensive experimental tests using glass beads (0-20 µm) as the particulate system. We show that the dimensions of spigot and vortex finder diameter can be effectively manipulated to change the separation performance of the system and the energy consumption. A CFD model was developed that is able to predict particle size distribution. The numerical results for the partition curves showed very good agreement with the experimental data. INTRODUCTION Small diameter hydrocyclones are a very attractive separation technology for fine particle suspensions. Since the hydrocyclone diameter is directly proportional to the cutsize that can be achieved, 10mm hydrocyclones have been shown to be very effective in collecting particles in the micron-size range. In addition, while in large hydrocyclones the bypass, i.e. the fraction of particles that report to the underflow without classification, is similar to the water recovery, in 10mm hydrocyclones the bypass fraction is considerably larger than the water recovery. Its high particle recovery and low water recovery makes small hydrocyclones ideal for ultrafine particle classification and dewatering applications in mineral processing. The separation of mineral suspensions achieved using small hydrocyclones has been the focus of various studies. Pasquier and Cilliers (2000) derived a general classification model from experimental data of fine silica concentration in 10mm hydrocyclones; the model was able to describe the fish-hook partition curve. The effect of operating conditions has also received some attention in the literature. Cilliers et al. (2004) showed that an increase in temperature positively effects the recovery of fine silica particles in small hydrocyclones, by increasing the bypass and decreasing the cutsize. Neese et al. (2015) showed that the cutsize in 10mm hydrocyclones can be further decreased by operating at higher pressure, which also trebled the throughput."

Jan 1, 2018

By A. Saramak

"The paper focuses on problems of atmospheric pollution by the dusts, produced during the course of crushing and grinding processes, and the main objective of investigative programme is an assessment of emission of particulate pollutants for following crushing devices operated in plant scale: impactors, cone and jaw crushers. All crushers operate in aggregate production plants in Poland. In the first stage of investigations there were determined dust emission levels and supporting characteristics for all crushers under investigation. Then there were introduced indices that allow for comparative analysis in terms of dust emission, for devices with different energy consumptions and comminution ratio. It appeared that crushers with high the overall dust emission do not always achieved unfavorable dust emission per comminution ratio or energy consumption. The introduced indices proved their usefulness, because they helped to carry out a comparative analysis among crushers, operating under different technological conditions. It is also easier to assess environmental impact of individual crushing devices, under analysis. Results of investigations also show that environmental impact of different types of crushers is diverse and it is difficult to compare dust emissions of various types of crushers without taking into account technological aspects (like throughput, comminution ratio, energy consumption, and others) of their operations.INTRODUCTION Mineral processing of raw material is a complex process, involving in general operations of size reductions and separation. Depending on the type of specific raw material, the technological circuit may include operations of comminution and size classification. This is a typical circuit for aggregate production. In ore treatment industry the process in much more complicated and include also a metallurgical treatment of ore concentrate – the final product from processing plant stage.In general, regardless the type of raw material, operations of size reduction are present in each technological circuit of mineral processing. Operations of crushing and grinding are an integral part of processing technology, because they play a crucial role in effective treatment of mineral raw materials (Gawenda 2013). Their duty is to liberate the useful minerals from the gangue in ore treatment industry, or to produce the material with the required particle size in case of aggregate processing. Crushing and grinding operations are of a high negative impact on environment and humans. They consume great amounts of energy, what indirectly contributes to higher emission of carbon dioxide CO2. Apart from energy, crushing and grinding device consume significant amount of steel and other metals and alloys due to high wear of working parts and grinding media. This is also of negative environmental impact due to emissions of additional amounts of CO2 in production of steel and other metals required as spare parts for comminution devices."

Jan 1, 2018

By M. Abdollahy

In this paper, the hydrophobicity of chalcopyrite particles produced with different laboratory mills has been studied; different grinding mechanism in themills made some changes in particles shape, Image Analysis (IA) method was used to determine the shape properties of chalcopyrite particles which are ground by a laboratory ball mill, rod mill and ceramic ball mill. The shape characters are stated in terms of shape factors such as circularity, convexity, roundness and regularity factor. Hallimond tube was used to float chalcopyrite particles followed by determination of critical surface tension of particles, this parameter used as a criterion to study the wetting behavior of chalcopyrite particles. The correlation between shape properties and critical surface tension of chalcopyrite particles showed that the hydrophobicity of chalcopyrite was affected by the shape. Investigations showed that the circular, round and more convex particles that produced with ceramic ball mill had lower hydrophobicity with higher critical surface tension (?c). The results also showed that the hydrophobicity of particles ground by ball and rod mills increased with the decrease of roundness, circularity, convexity and regularity factor of particles. Keywords: chalcopyrite, particle morphology, flotation, image analysis system, micro flotation method, hydrophobicity, shape properties

Sep 1, 2012