Search Documents

By P. Vijay Kumar

Phosphate minerals are conventionally concentrated by flotation process using soap or soap- light diesel oil emulsion as collector. Some plants use detergents such as sodium petroleum sulfonate or alfa olefin sulfonate to enhance efficiency of soap flotation. It is reported that urea a known hydrotrope enhances flotation efficiency of soap as efficiently as alfa olefin sulfonate or linear alkyl benzene sulfonate at bench scale tests. In the present study tri sodium citrate also a known hydrotrope is tested as promoter in the flotation of phosphate mineral from Eshidiya ore.

Sep 1, 2012

By K. Price, G. Wang, L. R. Moore, Y. R. Xiong, J. Gu

"Sand is a naturally occurring granular material that is a result of the physical or chemical breakdown of rocks. Raw/natural sand contains various minerals, and it is this combination of minerals that brings the value to the construction aggregate industry. However, it is the quartz component of sand that is valued in its application as industrial silica in glass, high purity quartz, foundry sand, and oil and gas fracturing. Depending on the industry, the grade requirements can be the concentration of SiO2, particle size or shape, as well as contaminants such as the heavy refractory minerals, clays, fines, and alkali metals. With the ever declining mineral feed grade, processors continue to face challenges making the industry specific concentrate grade. As such, it becomes more important to tailor make the processing reagents to fit the mineral, processing conditions, and desired quality specification. This paper focuses on the application of novel collectors towards the beneficiation of sand for each of the major industrial silica applications. INTRODUCTIONQuartz is a mineral composed of a framework of silicon and oxygen atoms. It is the second most abundant mineral in the Earth’s continental crust. There are many species of quartz, which are defined by the particle size, shape, and color. Silica sand is one of those species, which is the byproduct of the physical or chemical breakdown of quartz containing rocks or crystals. Geologist define silica sand as a silica mineral with a particle size between 0.05 and 2 mm in diameter (Zdunczyk, 2001). Silica sand has significant value to society in recreation (beach sand and toy boxes), construction aggregate (concretes and asphalt), industry (iron & steel casting, fracturing proppants, and glass), as well as specialty products such as semiconductors or silicon wafers used in electronics.The aggregate business is the dominant consumer of silica sand products. Conversely, glass making, foundries (casting material), abrasives, and fracturing proppants are the dominant applications for industrial silica sand. Not much beneficiation is required for sand products going into the construction industry, other than sizing and scrubbing to remove clay. However, the industrial silica sand applications are dependent on particle size, shape, and degree of contaminants, which sets the market value (table 1). Therefore, as the more specialty products are produced, more sophisticated techniques and chemistry need to be applied to ensure the appropriate quality is met."

Jan 1, 2018

By J. Y. Liu

The comminution in a high-pressure roller mill is modeled by an energy-based population balance approach considering three aspects of breakage taking place in the active zones of the mill: the interparticle breakage in the high-compression zone, the breakage at the edges of the rolls, and the pre-breakage in the acceleration zone. Together with an appropriate model of classification, this model can be used to simulate steady-state performance of closed-circuit grindings with high-pressure roller mill. After a brief description of the basic modeling approach, the algorithm of the steady-state calculation for a generalized grinding-classification circuit is presented, from which the circuit configurations commonly met in industrial practice can be derived. With an iron ore as feed material for example, simulation results are shown and discussed in respect of circulating load, specific energy consumption and product fineness for closed-circuit grindings under various operating conditions. The effects of stressing intensity, working gap, classifier parameters as well as circuit configuration on the overall circuit performance are investigated systematically by means of computer simulation.

Jan 1, 2014

By B. K. Gorain

Mining of low grade deposits along with the necessity to design and operate flotation plants with high throughput presents unique metallurgical and environmental challenges that need to be addressed to reduce project risks, improve project economics and to sustain the profitability of operations over the life of a mine. Some of the key challenges include poor recovery of valuables and concentrate quality issues due to complex mineralogy, the need to use poor quality water such as brackish or sea water, reduce environmental impact from the process, integrate flotation with hydrometallurgy to maximize precious metals recovery, escalation of capital and operating costs, use of unproven technology and constant use of larger equipment, high ore variability, worldwide constraints on resource availability and an ever increasing need for reliable metallurgical input to financial models to evaluate economic viability of projects. The need to develop effective solutions to these problems in a short time frame is becoming a key to the success of any new project and for sustaining the profitability of a mining operation. An integrated multi-disciplinary approach to problem solving is crucial with the need for a more lateral thinking along with strategic partnerships and collaboration involving the right players. This paper presents some of the key findings based on experiences from a large number of challenging projects and operations focused on solving complex flotation problems Keywords: mineral processing, flotation, flotation problem solving, flotation optimization, plant design, innovation

Sep 1, 2012

By M. Narasimha

The flow in a hydrocyclone classifier is highly turbulent complex nature of multi-phase structure, which has led designers to rely on empirical mathematical models for predicting the performance. A number of classifying cyclone models have been developed and successfully used in mineral comminution circuit simulators over the past four decades (Plitt, 1976 and Nageswararao, 1978). However, most of the mathematical models currently available to describe hydrocyclone classifier performance are based on single average mineral density component behavior. In industrial comminution circuits, the feed to the cyclone composed of a mixture of particles of varying degrees of liberation and sizes. The behavior of multi-component particles in a hydrocyclone is poorly understood and unaccounted for in most of the mathematical model equations available in the literature. There is evidence from a number of experimental data sets indicating the significant influence of the multi-component particles on measured cyclone performance. A concept for modeling the performance of hydrocyclones based on multi-component behavior is proposed in this paper. A set of semi-empirical model equations for cut-size, sharpness of separation are presented and the corresponding model parameters evaluated from the measured data are given.

Sep 1, 2012

By L. Gao, X. Gui

Fine coal obtained from Kailuan mine served as the processing object of this study. This material was difficult to separate. A flotation rate experiment was designed to investigate the process distribution characteristics of size and density during fine coal flotation. Size and density analyses of five clean were studied. The mineral morphology of flotation rate experiment cleaning was observed through scanning electron microscopy. The fractions -0.074+0.045 mm and -0.045 mm exhibited the best practical floatability and presented the highest combustible body recovery rates, but the selectivity and natural floatability of these two fractions were the worst. The - 0.074 mm fraction has contaminated the clean coal from the early stage of flotation, and the cumulative clean coal ash of -0.074 mm reached up to 17.20%. The low and middle-density classes displayed varying flotation behavior, but the flotation yield difference was only nearly 3%. The middle-density class caused the clean coal to have high ash content. The poor selectivity of fine coals, middle-density fraction, and fine mud resulted in high-ash clean coals during flotation. Thus, improving the selectivity of fine coal, restraining the flotation of fine mud, and grinding the coal to decrease the middle density mass fraction to liberate clean coals can yield high-quality clean coals through flotation.

Jan 1, 2014

By Edgar Schach, Tom Leistner, Markus Buchmann, Urs A. Peuker, Martin Rudolph, Marius Kern

"In this study, the flotation characteristics of a cassiterite-bearing fine-grained and complex skarn ore from a deposit in the Ore Mountains is investigated. The tests are performed using an oil-assisted column flotation approach to process very fine ore fractions and avoid losses of cassiterite into the tailings. First, process parameters are obtained for a finely ground artificial mixture of quartz, magnetite and cassiterite, simulating the real ore. Thereby, magnetite is used, as iron oxides can have a detrimental effect on the flotation due to a similar flotation behavior. In addition, they can act as a source of multivalent ions, which are known to reduce the concentration of collector molecules, active for flotation. Based on the results, selected parameters are further tested for cassiterite skarn ore from the Hämmerlein deposit including a pre-conditioning and a water exchange step to remove ionic contaminants. The process response is analyzed in detail by XRF (X-ray fluorescence) and MLA (mineral liberation analysis) to get a better understanding of the behavior of the single ore components. Sulfosuccinamate type surfactant is utilized as the collector, emulsifier and to reduce the froth destabilization through nonpolar oil. Sodium hexafluorosilicate is added as the depressant.INTRODUCTION Complex skarn ore deposits containing considerable amounts of tin, indium and other metals are located in the Ore Mountains region (Germany). In this study, a skarn ore from the Hämmerlein deposit was investigated. Due to the finely disseminated nature of this ore, past beneficiation attempts failed, and the ore was considered economically unprocessable. However, increasing resource demands brings it back into focus (Schuppan and Hiller, 2012). Cassiterite is the main tin bearing mineral in this ore. Due to its high density (~7 g/cm³), the predominant beneficiation technique is gravity separation (Angadi et al., 2015). Tin ores from disseminated deposits have to be extensively comminuted to reach a sufficient degree of liberation of the cassiterite grains. As cassiterite has a brittle nature, it is preferable enriched in small size fractions, during comminution (Angadi et al., 2015). Gravity separation methods become more and more inefficient for particles smaller 40 µm (Falcon, 1982), causing tin losses of up to 30 to 40wt.-% (Angadi et al., 2015). Thus, froth flotation of cassiterite was first utilized in Altenberg in the Ore Mountains as an additional processing step to reduce the cassiterite losses into gravity separation tailings (Bulatovic, 2010; Gruner and Bilsing, 1992). Although the reported lower size limits for an effective cassiterite floatability are often smaller compared to other minerals, the flotation performance is in general decreasing for small particle sizes < 10 µm (Trahar and Warren, 1976). Therefore, different approaches have been already investigated for the flotation of such fine cassiterite fractions to overcome the limits in particle size. Bilgen et al. investigated the shear flocculation of cassiterite with a sulfosuccinamate collector (Bilgen et al., 1994). The agglomeration flotation of cassiterite has been tested by Schubert et al. (Schubert et al., 1966), in which the selective coagulation of fine hydrophobic particles and oil droplets leads to an increase of the effective particle size. Recently, Leistner at al. investigated an oil-assisted agglomeration flotation for ultra-fine cassiterite ore fractions (Leistner et al., 2016). However, a poor response due to an increased concentration of Fe and Ca ions, unselective oil/gangue coagulation and froth instability, that is caused by oil/frother interactions, has been observed."

Jan 1, 2018

By T. Chmielewski

Unique mineralogical and petrological properties of black shale in the copper ore deposit of the Foresudetic Monocline (SW Poland) resulting from three lithological layers have been described in terms of its unfavorable behavior in the ore processing circuits. A concept of processing of a part of the black shale fraction from the flotation circuit of the concentrating plant by separating a by-product enriched in the shale matter was presented. This by-product represents the tailings of the first cleaning flotation and, as a hard-to-treat circulating middlings, overload the cleaning operation in the flotation circuit. It was found that the investigated by-product cannot be effectively up-graded using standard xanthate flotation. This is due to a fine dissemination of sulfide minerals in the dolomitic and clay shale particles significantly enriched in organic carbon. The content of the organic carbon is similar to that in the petrographically "pure" black shales. After a comprehensive examination of the shale by-product it was recognized that the investigated middlings can be regarded as a specific shale concentrate for individual processing. The effect of non-oxidative leaching of middlings with sulfuric acid on their further flotation was presented. It was shown that non-oxidative leaching is a selective process, in which calcium and magnesium carbonates decomposition leads to effective liberation of sulfide minerals which were finely disseminated in the hydrophilic carbonate gangue. Leaching of the flotation feed with sulfuric acid selectively decomposes carbonate minerals and consequently enhances flotation results. Saturation of leaching slurry with gaseous carbon dioxide favorably creates non-oxidative conditions and leads to a great decrease of the electrochemical potential of sulfide particles as well as hinders their solubilization. Partial carbonates leaching from middlings resulted in evident liberation of valuable minerals. Consequently, it resulted in an increase of both recovery and grade of concentrates obtained by flotation of shale by-product after non-oxidative leaching.

Jan 1, 2014

By D. DePaoli, P. Zhang

"Phosphate ore is one of the most significant secondary resources for rare earth elements (REEs), and Florida phosphate is of particular interest due to its much higher ratio of heavy REEs, especially yttrium. Analyses of numerous samples from different phosphate processing streams in Florida showed that heavy REEs account for about 50% of the total REEs in Florida phosphate with yttrium accounting for approximately 30%. It was estimated that the amount of yttrium from US phosphate processing could meet the world demand for this critical element. This research aimed at recovering both REEs and phosphorus from a phosphate flotation tails. This tails is composed of mainly silica and phosphate with a small fraction of heavy minerals including monazite and xenotime. Since the specific gravity of silica is 2.6 versus 3.2 for phosphate and 4.5-5 for rare earth minerals, pre-concentration of the minerals of interest by gravity separation was investigated first. A pilot scale shaking table was used in this study. One pass gravity concentration achieved a shaking table concentrate analyzing over 600 ppm REEs at about 40% recovery. Flotation of the shaking table concentrate resulted in a product containing 1809 ppm REEs and 26.37% P2O5 with corresponding recoveries of 73% and 82%. Sulfuric acid leaching at 75oC could recover over 60% REE and nearly all the P2O5. Higher REEs (>90%) recovery was achieved by conducting leaching at higher temperature with concentrated sulfuric acid. The phosphoric acid from leaching of the flotation concentrate is of superior quality compared with that generated from regular phosphate rock.INTRODUCTION Rare earths are a group of 17 elements including those of the lanthanum series, as well as the non-lanthanides, yttrium and scandium. These elements have very specific critical uses in a multitude of markets. For example, lanthanum is used as a catalyst in breaking down crude oil to produce gasoline, diesel and jet fuel and neodymium is the core magnetic component in high-strength magnets for electric car batteries, wind turbines and hard disk drives. Rare earths are also essential for many military applications. Many of these applications have no substitute materials and the move to green technologies has dramatically increased their demand."

Jan 1, 2018

Compressive crushing is applied in crushing plants used in mineral, mining, and aggregate in-dustry for fragmentation of rock materials. From a global perspective, the total volume of crushed rock is massive and corresponds to several billion tons. All societies have to fulfil a daily need of rock material products and its derivatives such as metals and minerals. The business for metals and minerals is global while the aggregates production is mainly a local industry. This paper presents a broader overview of optimisation with respect to product yield, use of natural resources and energy consumption. High level plant optimisation of compressive crushing plants is covered as well as real-time optimisation and optimisation of single production units. Each of three optimisation areas are presented and a discussion around how these three areas will be able to communicate with each other is given. Several models, e.g. process performance behav-iour with respect to wear, as well as fitness functions can be common for all three areas. Well-defined and representative fitness functions are of the utmost importance in order to assure that the optimisation results reflect the production targets. It is concluded that great benefits can be achieved by linking together different areas of optimisa-tion. The future for compressing crushing lies, without a doubt, in tailored processes both with re-spect to machines optimised for each customer, plant parameters and operation routines as well as an on-line adjustment, which takes into account current information and control possibilities.

Jan 1, 2014

By Bharat Garg

The coking coal or clean coal from raw material division, Tata Steel Ltd. is a prime source of energy for inhouse steel making. Coal reserves of semi soft coking coal at West Bokaro is beneficiated by dense media cyclone and froth flotation processes to produce clean coal. In dense media cyclone process two byproducts-middling and rejects are also produced along with clean coal. With the growing demand for clean coal, it becomes imperative to maximize the recovery of clean coal in beneficiation processes. This will help, not only in reduction in cost of production, but also in raw resource conservation, and proper utilization. In this context, a case study was conducted at West Bokaro to identify opportunities for clean coal recovery from by-products. This paper mainly discusses the process for recovery of clean coal from byproducts and study of further liberation of clean coal from byproducts for economic consideration.

Sep 1, 2012

By L. Li

Chemical composition, mineral composition, and iron occurrence state of main mineral are studied, Research of mineral processing technology is carried out according to ore features. The test results indicate, that through staged grinding-staged concentration process, the better separation index is up to 65.54%, iron preparation concentrate grade and 85.66% recovery with the fineness (-200 mesh) 45.88% in the primary grinding ore and the fineness (-200 mesh) 75.50%, in secondary grinding ore in the situation of best magnetic field intensity (roughing 0.2T and cleaning 0.15T).

Sep 1, 2012

By A. Kogelbauer, A. Stadtschnitzer, A. Boehm, F. Schillab

"The paper covers the design and implementation of an industrial dense medium cyclone plant for carbonaceous iron ore, the proving of efficiency as well as the development of a predictive model for plant control. The VA Erzberg GmbH mines about 12 Mio.t of carbonaceous rock ore at the “Steirische Erzberg”. Due to increased demand of the Austrian steel plants, the production of ore concentrate was raised by 30 % up to 3.0 Mio t/a during the last 5 years. One of the projects to realize the increase in capacity at improved concentrate quality was the implementation of a dense medium cyclone plant for the fine size fraction – 8 +1 mm replacing the former dry permanent magnetic drum separators. By physical separation the siderite variety “spateisenstein” (42% Fe) of a density of 3,8 g/cm³ is separated from ankerite (10 – 17% Fe), the second iron bearing carbonate with a density of 3,2 g/cm³, dolomite, calcite and silicate bearing schists. The feasibility of the process was proven by the test results obtained from a test rig, that was constructed and operated in close cooperation between the Chair of Mineral Processing, Montanuniversitaet Leoben and VA Erzberg GmbH. The density separation surpassed the efficiency of magnetic separation clearly shown by •- values. The plant performance tests (capacity 120 t/h) verify the cut densities defined by Tromp T50 -values and the assigned efficiency found in the pilot tests at varied settings of media density, pressure drop, cone angle and apex diameter. The test rig as well as the final process will be presented. In order to create a tool to predict the performance of the DMS in the centrifugal field at various settings for varying feed composition the experimental results from size and density testing are analyzed in a modified way to obtain physically justified, smooth approximations for the performance curves. Models developed on coal washing plants are checked for their validity at increased densities."

Jan 1, 2018

By Sanjeeva Latchireddi

The effective utilization of the energy in comminution devices depend on how efficiently the broken particles leave the breakage field as soon as they reach product size. In crushers the transport of broken particles smaller than CSS is done by gravity (vertical) thus allowing the energy to be applied to new particles. However, in AG/SAG mills, gravity becomes the energy field and the transport of particles is horizontal which needs a suitable discharge mechanism and has been found to have significant effect on grinding efficiency. The material transport in AG/SAG mills depend on how efficiently the discharge system (grate and pulp lifters) operates. Material transport plays a significant role on efficiency of horizontal grinding mills ? AG/SAG/Ball mills. The magnitude of benefits that can be achieved with efficient material transport in AG/SAG mills has been demonstrated in a Greenfield milling operation at Mirabela Mineração?s SantaRita Nickel operation located in northeastern part of Bahia in Brazil. This grinding circuit was commissioned in October 2009, which was designed as a typical SABC circuit to grind 4.6 mtpa (575tph) to produce a P80 of 125um with 10-12% ball charge in SAG mill. However, it has been operating as ABC circuit without any grinding media in SAG mill. The nameplate design capacity has been achieved in few days and has gradually increased to an average of +800 tph and still it is operating in ABC mode. The milling circuit commissioning resulted in small and relatively simple measures to rectify, which was reflected in the rapid commissioning of the milling circuit and it achieved the nameplate capacity within days. The Santa Rita grinding circuit consists of one 30?x 15.4? 8.5MW SAG Mill fitted with Outotec patented Turbo Pulp Lifters (TPL TM ) in close circuit with HP400 short head pebble crusher and one 20? x 28.4? 5.5MW Ball Mill in closed circuit with Warman cyclone cluster fitted with 10 x 26? CAVEX cyclones. This paper examines the comminution design process, operating philosophies, experiences, post commissioning optimization, and future development works. Evaluation of the milling circuit performance relative to the design criteria is also discussed. Keywords: Autogenous Grate (AG), Semi-Autogenous Grate (SAG, Turbo Pulp Lifter (TPL)

Sep 1, 2012

By F. Q. Dong

According to the principle that should be originated from nature, compatible with nature, used in nature and back to nature and based on conception of designing of eco-material, the author combined the ideas of material, environment, zoology and healthy. Properties of natural mineral materials were used to produce micro-aggregate elements by bionic method, so its components and function could accord with living environment. Eco-mineral functional materials which can adjust, purify and optimize the microclimate were reviewed. The authors pointed out the multifunction, com-pounding, the compound characteristics and integration regularities of micro-aggregates. It was the first time in the world to put forward the ?gene? technique or ?material chip? technique of manufacturing function micro-aggregates and eco-function elementary materials. The results of this re-search supported by the national ?863? Hi-tech Project, mainly including the high-efficient air purifying mineral compound material indoor, the clay elementary antibacterial materials, the masonry cement/coating/putty/compound with preventing radon radiation, environmental friendly composite functional coatings, mosquito repellent and healthcare material and zeolite-based energy-saving composite materials, were introduced. Finally, the foreground of mineral materials in the field of future advanced eco-friendly materials was also discussed.

Jan 1, 2014

By Bruce Mathema, Steven Huynh, Terry Cheng, Gerry Gomez

"The use of PM40N, a specialty precious metals promoter in conjunction with a standard Xanthate based collector was extensively investigated in the flotation of a complex, silver-bearing, lead-zinc ore containing naturally occurring graphitic gangue. The ore, considered difficult to treat with conventional reagents, was tested at plant scale to determine the impact of the promoter on silver recovery, lead grade and also on the amount of zinc misplaced to the final lead concentrate.Initial laboratory-scale rougher flotation testing implied significant improvements in the recovery of silver and lead with a marginal amount of zinc displaced. Subsequent mini pilot flotation tests further revealed that a gain in selectivity and recovery could be achieved by adjusting PM40N promoter dosage and incorporating a cleaner flotation step, further improving rejection of sphalerite. Plant trials resulted in an improvement of 3% in Silver recovery coupled with a 2% increase in recovered lead whilst maintaining lead grade in the lead circuit.To date, the use of PM40N as a promoter has enabled the processing operation to significantly increase its plant economics. The partial replacement of the standard Xanthate based collector has also reduced the overall quantity of Xanthate required in the standard circuit by approximately 10% - which is a positive impact on the environment. It is envisaged that further optimization of plant parameters will favor stable operation and continue to boost revenues generated by subsequent improvements in silver metallurgy."

Jan 1, 2014

By R. K. Dwari

The electrostatic beneficiation of coal is based on tribocharging characteristics of ash forming minerals and coal particles. The tribocharging of quartz, pyrite and coal particles contacted with various metals and polymeric materials have been measured and the charge acquisition is assessed through surface energy calculations from liquid contact angle data. The contact angles, before and after tribocharging of solids, are measured using Krüss tensiometer and Washburn?s method where the sample holders in tensiometer are specially constructed with tribocharger materials. The charge polarity and amount of charge acquired by quartz, pyrite and carbon with metal tribochargers were found in good agreement with the reported work functions of the contacting surfaces. The charge results with polymer materials differed from the work function values, presumably caused by surface contamination. The surface energy of quartz calculated by all the theoretical approaches in the literature showed that the tribocharging increases the surface energy. Both polar and non-polar components computed from Fowkes and Owens-Wendt-Rabel-Kaelble approaches dis-play that both these components increased after triboelectrification. However, the polar component divided into acid and base components, as in van Oss approach, manifest decreasing acid part and increasing base part. Since quartz charged negatively during tribocharging with metal surfaces and therefore accepted electrons, the determined acid and base surface energy components are consistent with charge transfer process. The results also elucidate an explicit correlation between the charges generated by powders and the surface acceptor (acid) and donor (base) electronic states and thereby the work functions. A novel fluidized bed tribocharger was designed and developed with internal baffle system for efficient contact electrification of mineral and maceral to produce high differential charging for efficient separation. The results achieved on coal with 45% ash content are presented and discussed.

Jan 1, 2014

The ever increasing demand for energy and the progressive depletion of crude oil resources, have renewed interest in oil shale as an alternative fuel resource. Weathered oil shale samples were assembled from El-Nakheil phosphate mine in Quseir area, Eastern desert, Egypt. The oil shale samples were prepared and analyzed by XRD (X-ray diffraction), XRF (X-ray fluorescence spectrometry), and optical microscopic techniques. Rock-Eval pyrolysis and total organic carbon were used to study shale hydrocarbon potential. A leaching procedure using inorganic and organic acids was used to selectively dissolve the oil shale associated ash forming minerals. XRD results showed that calcite is the dominant carbonate mineral, whereas primary silicate minerals are quartz and montmorillonite. SEM (Scanning Electron Microscopy) observations indicated that the organic matter is dispersed throughout the rock matrix. The acid soluble fraction upon leaching was determined to be 37.59 and 42.74 wt% by using 5% HCl and 10% HCl, respectively. The TOC was increased from 20.78 to 29.88 and 34.09 wt% by using 5% HCl and 10% HCl, respectively. Keywords: el nakheil oil shale, characterization, xrd, xrf, sem, elemental analysis, proximate analysis, ultimate analysis, thin section, rock eval pyrolysis, acid leaching

Sep 1, 2012

By Dmitriy Makarov

The paper presents the modeling and analysis of oxidation of pyrite copper-zinc ore samples from the Letnee, Yaman-Kasy and Valentorskoye deposits. It is found, that the oxidized samples contain copper and zinc sulfates that are leached under the sample and water contact. It is shown, that sulfide floatability is decreased by the longer-term oxidation.We advise to improve nonferrous metals recovery by joint leaching and ultrasonic treatment of oxidized compounds. Study of the geotechnological processes of non-ferrous metal extraction, on the basis of two copper-zinc ore deposits shows, that heap leaching is of little use for the ores of the Letnee deposit. Leaching results for the Yaman-Kasy ore showed more promise.

Sep 1, 2012

By D. Saramak

The proposal of the nip zone angle determination in HPGR crushing process is presented in the paper. Knowledge of the nip zone angle value, in turn, makes it possible to determine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll?s geometry, and the change of the HPGR chamber?s volume together with the roll rotation, while the second one considers the outlet gap width impact. Results of the nip zone angle calculations according to both methods are similar and show convergence with the real operating conditions. The verification was carried out in a piston-die press, and experimental results show that methodology of the nip zone angle determination presented in the paper has its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization. Keywords: HPGR, comminution, nip zone, ore processing

Sep 1, 2012