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Calcium sulfate whiskers are considered to be a prosperous reinforced material in application due to their high mechanical properties. But the hydration occurs easily at moist atmosphere or in aqueous solution. The surface topographies of the calcium sulfate hemihydrate whiskers and the hydrates were analyzed by on-line observation and using XRD. The results indicated the transformation of the crystal type and shape of calcium sulfate hemihydrate whiskers and the reduction of whiskers? aspect ratio. The hydration process of the calcium sulfate hemihydrate whiskers and the effective parameters were further discussed based on FT-IR measurements. The conclusions were obtained that the hydration of calcium sulfate hemihydrate whiskers can be divided into the three phases, namely, initial hemihydration phase, dehydration phase, and coarsening, dissolving and the re-formation of calcium sulfate dehydrate crystal phase. In addition, it was found that in the hydration process of calcium sulfate hemihydrate whiskers the calcium sulfate dihydrate whiskers are formed at first and then converted into the calcium sulfate dihydrate with different crystal shapes, but in the hydration of gypsum hemihydrate the gypsum dihydrate is formed without transition products. The surface active site-calcium ion which has strong trend to react with H2O, the surface ?OH and the inner channels are considered to play important roles in the hydration process of calcium sulfate hemihydrate whiskers.

Jan 1, 2014

By Chuanyao Sun, Yang Yu, Zhen Guo Song, Wei. Ming’An

"Carbonate minerals are very important mineral source of extracting metal, radioactive element and rare earth elements. Furthermore,some carbonate minerals, such as calcite and dolomite, are common and important components of sediments and sedimentary rocks. Many flotation processes involve the separation of valuable minerals with carbonate minerals. So it is of great significance to the flotation theory and industrial practice to investigate the flotation behaviors of carbonate minerals. As regulators, metal ions play a major role in minerals flotation. The study of influence law of metal ions on minerals flotation is helpful to eliminate or utilize the effect of metal ions. In this study, calcite and smithsonite laboratory scale flotation, surface analysis and zeta potential determination in the presence of Fe(II) ion were performed to investigate the effect of Fe(II) on carbonate flotation. The results show that Fe(?) depresses the flotation of calcite and smithsonite. The depression effect of Fe species on calcite and calamine flotation can be improved with the increase of Fe(?) concentration. The zeta potential measurements and surface analysis show the existence of iron hydroxide products on mineral surface, which may be link to carbonate site instead of exchanging with calcium on the mineral surface. Fe species on the mineral surface inhibit the interaction between the reagents and calcite/smithsonite through the formation of surface precipitation coating on the calcite/smithsonite surface when the Fe(?) concentration is higher."

Jan 1, 2014

By R. Shiva Kumar, G. Sreedhar, S. Sharma

Some of the Indian origin iron ore deposits located in Bellary, Karnataka province are having peculiar characteristics of Iron ore deposits (Hematite) having Iron above 64% and 30-40% lump (-30+6mm) recovery which are not suitable to use in blast furnace due to not meeting the specification of Tumbler Index and Abrasion Index. In general for high grade Iron ores, process flow sheet involves crushing and screening (dry/wet). In the contest of high grade Iron ores located at Bellary sector of Karnataka state in India, lump generated from this process could not attain the required physical properties (Tumbler Index, Abrasion Index) and metallurgical properties , even though the grade of the lump ore is above 64% Fe. Washing techniques like Drum scrubber and Log washer play major role in improving the metallurgical properties of Iron ore lumps by removing the light and hard layers of clay, silica coated over the lumps. In this study the effects were compared of drum scrubbing and log washing on iron ore lumps. It is found that by incorporating simple washing technique i.e. drum scrubbing or log washing, Tumbler Index of Iron ore Lumps could be increased from 74% to 78% which is acceptable for use in Blast furnace. From the Drum scrubber and Log washer tests, it is clear that Log washers have an edge over Drum scrubber in removing hard coated clay on surface of Lumps. This simple washing technique facilitate us to utilize the lumps directly in blast furnace and eliminate the unnecessary crushing and grinding of the ore so as to meet the specifications of Sinter fines and pellet feed.

Jan 1, 2014

By John A. Herbst, Ming Song, Xiangjun Qiu

"It has been known for sometime that as wear occurs in tumbling mills there is an associated change in mill throughput. These changes have traditionally been simplistically, attributed to “mill volume effects”. New high fidelity simulation (HFS) tools (involving DEM, CFD and Breakage models) are now giving new “microscale” insights into the complex interactions that occur between evolving lifter/liner profiles and breakage. An illustration of this analysis is shown in Figure 1 below.Here we see that after a new lining is installed (Region I) the wearing process reduces the liner thickness resulting in a larger power draw and an associated higher throughput until Region II is reached. By this point the lifter height is reduced significantly changing charge motion (less cataracting) the power begins to decline, but the comminution efficiency increases with this type of “calmer” breakage environment therefore the throughput continues to increase. In Region III the lifter is no longer providing the minimum required charge lifting action, the power and the throughput both drop off significantly. In the last two stages the behavior is especially complex because throughput is not linearly related to power since grinding efficiency is changing.The study described here shows that these new HFS tools allow the design of wear part profiles which will maximize mill productivity over the entire life of liner/lifter systems. A simple example of such a design procedure is shown involving the selection of a sinusoidal profile for a 34 ft diameter SAG mill.The paper discusses how the principles exposed in this simple example can be applied to search for an optimal profile in which non-standard modifications are allowed to compensate for throughput or wear shortcomings of standard profiles."

Jan 1, 2003

By M. Naymanbayev

The characteristics of the mineral composition of ores and valuable set of components: the technology of processing depending on the type of mineralization, the nature of the impregnation of ore minerals and their composition have been considered. There have been given technological schemes for processing concrete objects. The analysis of fitness fields for industrial development (degree of scrutiny, the effectiveness of developed enrichment and hydrometallurgy technology) has been provided.

Sep 1, 2012

By N. Naude, W. P. Roux

"Traditionally minerals processing equipment, such as jigs, are studied by characterising the feed and products from these processes. With this approach important details on the mechanisms of a process can be overlooked since assumptions have to be made on the internal operations of the equipment. Positron Emission Particle Tracking (PEPT) is a non-invasive technique that can be used to track a particle’s movement inside a closed vessel. PEPT makes it possible to observe the inner workings of a process, providing new information that was unattainable only a few years ago. Jigging has long been considered as one of the most difficult mineral processing techniques to model, due to the complexity of the mechanisms contributing to the separation of minerals during the jigging process. In this investigation PEPT was used to study the particle flow inside a laboratory batch jig. The aim was to determine if the particle trajectories could provide new insight into the jigging and its mechanisms. Three dimensional particle trajectories were observed with spatial and temporal resolution high enough to see details of the individual pulses during jigging. It was found that the pulse height is very dependent on the position in the jig bed. The vertical component from the trajectories showed the rate at which particles move through the jig bed (stratification rate) and it was seen that the density of a particle affects the stratification rate more that the particle’s size and that the shape in the range that was tested had little to no influence. Other phenomena such as a circular flow pattern was observed inside the jig and it was found that smaller lower density particles are affected by this circular flow pattern which tend to disperse these particles throughout the jig bed. Visualising the flow inside a jig by means of PEPT has shown to be instrumental in the deeper understanding of the process."

Jan 1, 2018

By Fedotov Pavel

"Today the main objective of improving the process of ore dressing is to reduce energy consumption and performance of the basic rule of auxiliary enrichment processes. One of the modern means of ore destruction with a minimum of energy consumption is the interparticle fracturing, for example in the roller press. There still remain the unsolved problems of the energy consumption determination and the particle size distribution of the crushing product .Existing methods for determining these parameters are empirical and require considerable expenses and time. The improved finite element was developed to solve these problems using finite element contact interaction of the rock. Also it was developed to clarify the stress-strain and the rock fracture energy in a layer. These elements are used to study ore destruction in the layer and allows to create a model taking into account the interaction of crushing particles surfaces. The same algorithm was developed determining crushing product particle size distribution in the layer on the base of the Bond’s theory of crushing. The presented finite element model allows to determine the quantity of strain energy and particle size distribution of crushed product during the destruction processes of the material in the roller press with fair accuracy."

Jan 1, 2014

By Pawel Strzalkowski, Marta Baszczynska, Urszula Kazmierczak

The paper presents issues related to interference of mining activities with the environment. Exploitation of mineral resources causes primarily a modification of the landscape. All of the negative impacts on environment are short-lived and last as much as it takes to exploit the raw material. After the mine closure reclamation is necessary during which all aspects that reduce harmful effects of the mining activities on the environment must be taken into account. Current ways of reclamation allow recreating natural environment, which is different from the original and enriched in diverse new values. This requires propositions of new forms of converted land development through a detailed analysis of technical, natural, planning, economic and social sphere requirements. Before making final decisions regarding selection of direction of reclamation, a thorough analysis of the key factors has to be carried out. All steps related to the implementation of the reclamation project are shown in the paper using Limestone Mine "Górazdze" located in the south-western part of Poland as an example. This paper also presents an analysis of current ways of post-mining reclamation towards agricultural and forestry landscape, along with our own suggestion for their extension in order to preserve biodiversity. For choosing optimal solutions the most relevant criteria were considered: existing natural values and possibility of their protection. Taking into account the economic and social aspects, supported by natural potentials, implementation of tourism and recreation in this area were proposed. It was shown that this proposition would not interfere with the current trends of the natural landscaping. Finally, after completion of reclamation and land development in the considered mine area, creation of a geo-park was proposed along with appearance of geotourism in the area. To illustrate the proposed forms of post-mining land development in the form of maps, an ArcGIS(ESRI) software was used.

Jan 1, 2014

By David De Klerk, Maximilian Richter, Thirunavukkarasu Pathmathas, Indresan Govender

We consider the average power dissipation distribution for dense granular flows of an idealised mono-sized charge (5 mm glass beads) in a 300 mm diameter tumbling mill operated in the cascading-to-cataracting Froude regime. By combining the inherent frictional nature of particles within a dense flow regime and noting that tumbling mills are typically characterised by collisional and turbulent stresses, we derive the power dissipation distribution for athermal boundary conditions. The input data to the model (velocity, solids concentration, pressure and flow depth) are obtained directly from non-invasive measurement using a nuclear imaging technique: Positron Emission Particle tracking (PEPT). The power dissipation due shear stresses is shown to be the dominant mode of dissipation in the tumbling mill with up to two orders of magnitude difference between pressure induced dissipation and shear.

Jan 1, 2014

By Gurubasayya Swamy

This paper presents the performance study of sag mill in the processing of gold ore. Deterioting ore grade and high demand of metals has tremendously influenced the SAG mills. Today?s high capacity Semi-autogenous grinding (SAG) mills expand vast amounts of energy and in doing so consume tons of shell liners and steel balls, while processing ore. Semi-autogenous (SAG) mill performance is influenced by ball charge, feed properties, shell, grate, and pulp lifter design. In the performance study of SAG mill, based on the results obtained it can be observed that SAG mill performed better at feed size +4 inch and grinding media consumption 0.90kg/mt. In the present study the effect of crusher bypass on SAG mill performance, an immediate drop of throughput ranging from 10-20tph is observed. Keywords: sag mill, pulp lifters, grinding media, energy, consumption, throughput

Sep 1, 2012

By Dilip Kumar Mohanty

In today?s world, Sustainability is the key issue before the mankind. With the ever-increasing population & unimaginable boost in industrial growth to cope up with a steady increase in demand and fast change in life style of a human being, the natural resources are exploited to such an extent that the very existence of living beings in this earth planet is threatened. In such devastating situation, the concept of Sustainability emerges out as a great savior. This concept focuses on minimum/ judicious use of natural resources, thereby preserving the resources for future generation while meeting the bare minimum requirement of the present generation. For an emerging economy like India, Mining and Mineral based industries form the back bone of our economic development. Thus, sustainability of mining and mineral processing industry has a far reaching impact on sustainable economic development of our nation. While at a macro-economic level, we have to strike a balance between economic development vis-à-vis socio-economic & environmental impacts, Industries have to ensure judicious and frugal use of natural resources by making use of energy efficient plants & machineries and adopting befitting technology for reduction & recycling of waste. In the context of the above, it would be interesting to look into the sustainability measures taken up by National Aluminium company (Nalco) at its Crushing & conveying plant at Panchpatmali Bauxite Mine, which is incidentally Asia?s largest Bauxite Mine. In the backdrop of the above stated facts, in this paper the authors make an attempt to bring out the sustainability issues in areas of energy conservation, environmental impact/pollution vis-a-vis mitigation measures adopted in crusher & conveyor plant of Panchpatmali Bauxite Mine & CSR / peripheral developmental activities undertaken by Nalco to mitigate the socio- economic impacts. Keywords: sustainability, energy efficiency, recycle, csr, peripheral development

Sep 1, 2012

By K. Saberyan

In this study, solvent extraction of zirconium by using triphenylphosphine oxide as extractant has been investigated. The results showed that extraction of zirconium by triphenylphosphine oxides in nitric acid and hydrochloric acid media were negligible. Extraction of zirconium in acetic acid media with concentration of 0.01~0.2 M has been studied and the results showed that the maximum percent of zirconium extraction was 40% in acid acetic with concentration of 0.01 M. By addition complexing agents such as potassium thiocyanate with the concentration of 0.01~0.2 M zirconium extraction increased up to 86% in 0.2 M potassium thiocyanate. By addition of sodium salicylate with concentration of 0.01 M and in pH=2.5, the maximum extraction of 96% was achieved. The striping of zirconium from organic phase can be carried out by 0.5 M solution of sulfuric acid.

Jan 1, 2014

By Y. E. Brylyakov, M. A. Kostrova

"The apatite staffelite ores (ASO) of Kovdor deposit are dominated by fine-grained aggregates containing both phosphate minerals and silicates — vermiculite, smectites, zeolites. These minerals exhibit ion-exchange properties. In this connection, the magnitude of cation exchange, along with the content of P2O5 and CO2, is an important property of apatite staffelite ore, which largely determines the performance of concentration processes. In the examined ASO samples, the magnitude of cation exchange measured in terms of Ca2+ is 2546-4790 g/ton. The conducted laboratory studies of apatite staffelite ores with various mineral composition showed that adding calcined soda improves the recovery of P2O5 into the flotation concentrate. Full-scale tests were conducted at the apatite staffelite ore processing plant at Kovdor Mining and Concentration Operation and demonstrated the high performance of the proposed agent treatment. The test results showed that in the flotation of apatite staffelite ores, the optimum calcined soda feed rates range from 3,500 to 5,000 g/ton of the flotation feed. With close flotation feed and concentrate grade parameters, the P2O5 recovery gain is 17%. The effect of adding soda is associated with the desorption of the hardness cations from the minerals, precipitation in the pulp and, accordingly, improvement in the ionic composition of the liquid phase of the flotation feed due to a reduced content of calcium ions. Based on the test results, the proposed agent treatment with an elevated feed rate of calcined soda was implemented at Kovdor Mining and Concentration Operation in the flotation of apatite staffelite ore. The apatite staffelite ores (ASO) of Kovdor deposit are dominated by fine-grained aggregates containing both phosphate minerals and silicates — vermiculite, smectites, zeolites. These minerals exhibit ion-exchange properties. These minerals have certain properties requiring a more detailed examination for a better understanding of the flotation properties of apatite staffelite ores."

Jan 1, 2018

By Vladimir Vigdergauz, Elena Belogub, Dmitriy Makarov

The influence of supergene oxidation on physicochemical and technological properties of polysulfide ores was studied. Modeling and analysis of oxidation pyrite copper-zinc ore samples from the Valentorskoye deposit show that sulfide floatability is decreased by the longer-term oxidation. The treatment of oxidized samples by sulfuric acid in oxidative conditions and its impact on the elemental sulfur composition on the surface of sulfides was discussed. It is shown that an enhancement of the floatability of sulfides of oxidized polysulfide ores after leaching by sulfuric acid could be perspective for the developing of combining floatation-hydrometallurgical technology of the nonferrous metals recovery.

Jan 1, 2014

By V. G. Minenko, V. A. Chanturiya, A. L. Samusev

Eudialyte is one of perspective resources of zirconium and other rare earth elements (REEs). Large reserves of eudialyte concentrated in the Murmansk region of the Russian Federation. Usually, technologies of REE treatment include the decomposition of eudialyte concentrate in different acidic, extraction and utilization of all components. The main problems in the leaching of eudialyte include are: the formation of an unfiltered silicon-containing gel; low recovery of REE; difficulty extraction of metals from the productive solution; high aggressiveness of the reagents. One of the promising trends of intensification of the processing of hard-to-degrease rare metal raw materials is the use of energy methods for affecting mineral suspensions. These methods make it possible to increase the efficiency of break up fine-dispersed mineral complexes and extracting micro- and nanoparticles of a valuable component in subsequent deep processing. The purpose of this work is to investigate the effect of energy impacts on the nitric acid leaching of eudialyte concentrate. Experimental studies were carried out in a developed laboratory facility that makes it possible to evaluate the effect of electrochemical, ultrasonic and combined effects on the leaching of zirconium and REE from eudialyte concentrate. The studies carried out on the samples of eudialyte concentrate with the size class of -0.315 + 0.063 mm showed that the use of electrochemical and acoustic effects increases the extraction of ZrO2 in the production solution in 1.6 - 2.5 times, REE in 1.3 - 2.2 times, respectively. An analysis of the microstructure and phase composition of the surface of the eudialyte concentrate showed that the intensification of the leaching process is due to surface cleaning from the silicon-containing gel, as well as the opening of capillary channels and microcracks, which accelerates mass-transfer processes. The results obtained open wide opportunities for creation of modern and effective technology of processing of eudialyte concentrate, producing high-quality zirconium products and REE.

Jan 1, 2018

By Aldo Cipriano, Fernando Estrada

The mining industry is in search of control strategies that allow considering a global optimization of their processes, ensuring their stability. This has led to the application of recently developed control techniques on large-scale systems in the mining processes. One of the most important process of the mining industry is the mineral grinding, as the product particle size impacts, in a significant manner, the recovery rate of the valuable mineral in the separation stages. As a solution, a centralized hybrid model predictive control (HMPC) is presented; this control approach maintains the product particle size on a defined range and minimizes energy consumption, maintaining the grinding plant in a stable operation. As a comparison, a conventional model predictive control with an expert system to handle discrete events was developed, showing HMPC is a suitable solution that can used in the grinding process, with the benefit that it handles in the same controller both discrete and continuous dynamics and events.

Jan 1, 2014

By J. Jávor

The response of the air/water interfaces to deformation in presence of surfactants is affected by the adsorption/desorption rate, re-orientation and exchange rate of surfactant. These surface properties can be observed using equilibrium and dynamic surface tension and surface elasticity measurements. However, the effect of these parameters on bubble size in dynamic conditions has not been studied due to the difficulty in capturing freshly formed bubbles in dynamic conditions. The paper presents a new experimental set-up designed and built at the Aalto University, called Shear Force Observation Chamber(SOC). The setupallows the monitoring and analysisof freshly formed air/liquid interfaces in dynamic conditions and facilitates the study of the effect of dynamic surface tension and surface elasticityon freshly formed air bubblesin presence of surfactants. The method helps to establish correlation between bubble size and dynamic interfacial properties and bubble-bubble interaction in turbulent flow. Dowfroth 200, Nasfroth 240 and Dowfroth 250 commercial flotation frothers were tested in this study. The results show a marked difference between results obtained in dynamic conditions compared to the static conditions. The results are presented and the reasons and implication to flotation modelling are discussed in the paper. Keywords: shear force observation chamber, flotation frothers, flotation bubbles, critical coalescence concentration

Sep 1, 2012

By T. Ueda, T. Oki, S. Koyanaka

"Accurate assessment of the liberation state of crushed ore particles is important for efficient mineral processing. In general, the liberation state is assessed by two-dimensional (2D) measurement of polished ore sample sections. However, this 2D measurement inevitably suffers from overestimation of the degree of liberation, known as stereological bias. This arises from the fact that biphase particle sections of which only one phase happens to have been cut are indistinguishable from liberated particles. To date, several stereological correction methods have been proposed, but their applicability for various types of particles has not yet been sufficiently examined, and this tends to undermine their practicality. We have addressed this problem using a numerical-analytical approach in which various types of biphase particles are modeled, and the 2D sectional information is compared with actual three-dimensional (3D) information. Through simulations, we revealed a general relationship between the internal mineral structure of particles and the stereological bias. Finally, we have developed a unique stereological correction method in which the texture (a 2D pattern characteristic) of particle sections is used to estimate the internal structure of particles, and thereby the stereological bias. KEYWORDS Mineral liberation, stereological bias, texture analysis INTRODUCTION Mineral liberation assessment of 2D particle sections inevitably suffers from stereological bias; that is, overestimation of the degree of liberation. Stereological bias is caused by the fact that a composite particle can be misidentified as a liberated particle when only one phase happens to have been cut in sectional measurement. Stereological bias has attracted attention since Gaudin pointed out its importance in 1939 (Gaudin, 1939). Several attempts have been made to measure the 3D liberation state directly, avoiding the bias, using X-ray computed tomography (Gay and Morrison, 2006; Lin and Miller, 1996; Miller et al., 2003; Miller et al., 2009; Reyes et al., 2017; Videla et al., 2007). These have provided useful information through laboratory testing, but further technical refinement is necessary for practical usage, to overcome the technique’s limitations in terms of resolution, assessment of minerals of similar density, and speed. Therefore, for practical purposes, detailed information regarding mineral phase geometry is obtained by sectional analysis, using automated scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX)-based analysis (e.g., with a mineral liberation analyzer (MLA) (Fandrich et al., 2007; Sandmann, 2015)); and the development of an effective method of stereological correction, which predicts the relevant bias and transforms the measurable 2D degree of liberation into its 3D counterpart, is an important research aim."

Jan 1, 2018

By Renato Oliveira, Walter Valery, Alex Jankovic, Birol Sönmez

"The ball mill is the most common ore grinding technology today, and probably more than 50% of the total world energy consumption for ore grinding is consumed in ball mills. On the other hand, high pressure grinding roll (HPGR) technology is relatively new to the mining industry, with significant application only since the beginning of the 21st century. Both ball mills and HPGRs are typically used in closed circuit with classifiers. There is a general consensus within the industry that classification efficiency and circulating load both have a major effect on the efficiency of closed circuit ball mills. Metso Process Technology & Innovation (PTI) conducted a laboratory test program to understand the relationship between classification efficiency and circulating load, and the impact on the performance and capacity of ball mill circuits. However, the effects on HPGR performance are significantly different. Metso PTI has initiated a pilot scale test program to evaluate the size reduction performance of the HPGR under different circuit configurations. A series of pilot scale HPGR locked cycle tests were performed to simulate the following circuit configurations: including closed circuit with a screen, partial product recycle and edge recycle. This paper discusses the results from the pilot scale HPGR and laboratory scale ball mill test programs. The effect of circulating load and classification efficiency on the performance of ball mill circuits is compared to the effect on HPGR circuits. The fundamentals of grinding behavior are also discussed in order to explain the difference."

Jan 1, 2014

The air recovery from a flotation cell is the fraction of inlet air which overflows the weir as un-broken bubbles. The air recovery is an important factor in froth phase phenomena; such as gangue entrainment and froth recovery. Increasing the air recovery, results in a higher recovery of attached mineral particles. Air recovery can be measured experimentally on plant using image processing of the top surface of an overflowing froth. The air recovery is directly linked to froth stability and the bursting rate of the bubbles at the froth surface, making it very difficult to predict. Experimental results show a very strong correlation between the superficial velocity of the inlet air and the superficial velocity of the air leaving the cell through the froth surface due to bursting, calculated from the experimentally measured air recovery. This correlation holds over multiple banks from different plants. Development of a power law equation around the inlet air velocity and the bubble solids loading on the froth surface allows the superficial air velocity through the top surface of the froth to be predicted, and from this the air recovery. This model is valid for use when operating beyond the peak in air recovery.

Jan 1, 2014