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By D. M. R. Sekhar

Certain types of rock phosphates of sedimentary origin are applied to acidic soils as fertilizer directly. Recent research in India showed that high grade rock phosphate in fine size when used as a mix with organic manure works as efficiently as di-ammonium phosphate (DAP) in alkaline soils. The rock phosphate from Jhamarkotra, India (sedimentary origin), Egypt (sedimentary origin) and South Africa (volcanic origin) showed good agronomic efficiency when used as Phosphate Rich Organic Manure (PROM). Further PROM shows equal residual effect. The results of efficiency of PROM made using two grades (+ 24% P2O5 and 34% P2O5) of rock phosphate mineral from Jordan show that low grade rock phosphate slimes are as effective as high grade phosphate concentrate when used in PROM. Also PROM is very effective in the saline soil of Eshidiya desert where DAP is not at all effective.

Jan 1, 2014

By P. Harris, D Bradshaw

"Comparison of the two most commonly used classes of depressant in the South African platinum industry is complicated by the fact that these polymers induce different effects on the surfaces onto which they adsorb. The use of carboxymethyl cellulose (CMC), which is ionically charged in solution, can lead to increased particle dispersion in addition to the effect of reduced surface hydrophobicity (depression). Guar is typically only slightly charged in solution. Comparison of these two depressants is complicated since it is uncertain whether differences in their action is a result of either depression of dispersion effects.This work investigates the role of dispersion independently to that of depression in the batch flotation of a platinum bearing ore. An inorganic dispersant, sodium hexametaphosphate (NaHMP) was added in parallel to the uncharged guar depressant to simulate the action of depressants with varying degrees of dispersion. By distinguishing between the material recovered by entrainment and the floatable gangue and by including the effects of froth stability it was possible to decouple the effects of dispersion and depression.The results show that both dispersion and depression led to increased grade of the sulphide minerals. Depression leads to a decreased recovery of floatable gangue minerals. Dispersion leads to an increased recovery rate of these minerals and an accompanying decrease in froth stability."

Jan 1, 2003

By Zofia Swierczek

This paper reports the results of a detailed mineralogical study of typical, low-grade Australian nickel laterite run-of-mine ores. Successful development of an effective beneficiation process for upgrading such low grade laterite ores relies on good knowledge of the laterite mineralogy and the value metal(s)? distribution characteristics. Both QEMSCAN and quantitative X-ray diffraction techniques were used to conduct the mineralogical analysis of three types of laterite ores, and the results were compared with those obtained by chemical analysis. Some of the major challenges faced included accounting for the mismatch between the nickel values measured by QEMSCAN and those recorded by chemical analysis. This was primarily due to the relatively low concentration of nickel in the ores and its wide dissemination among several major host minerals in complex association. Careful analysis showed that the limit of nickel detection in iron oxide host mineral grains under normal operating conditions was around 4%. Keywords: nickel laterites, mineralogy, characterisation, QXRD, QEMSCAN

Sep 1, 2012

By Z. G. Song, C. Y. Sun, X. R. Zhang, Y. Yu

In skarn type scheelite deposit, there are calcium minerals with floatability similar to scheelite, such as calcite, fluorite, etc., which are difficult to separate. Heating cleaning method developed by Petrov has been widely applied in processing rough concentrate of scheelite for nearly half a century, but there exists a general lack of full understanding of the interaction between floatation reagent and mineral particles surfaces. The mechanism on separation of scheelite and calcium minerals in heating cleaning process was investigated by mineral flotation experiments, XPS analysis, as well as solution chemistry and crystal chemistry calculations. The results showed that the sequence of minerals floatability using sodium oleate as collector and a large amount of sodium silicate as modifier in heating flotation test was scheelite > calcite > fluorite, which was the same as solution chemistry calculations based on Gibbs free energy vs. pH and also the same as Ca-X intensity order by crystal chemistry analysis. There are two sides about the mechanism of heating cleaning method: one is that the adsorbed collector on calcium minerals surface is desorbed more easily than scheelite, and the other is selective dissolution of calcium ions from the mineral surface because of Ca-X intensity difference in heating and stirring process.

Jan 1, 2014

By H. H. Li

Reverse flotation is usually used for hematite/silica or bauxite/clay flotation separation in which the silica or clay is floated and rejected. Some properties of these silicate minerals such as particle size and surface characteristics have significant effect on their flotation behaviours. Firstly, the silicate mineral particles (especially clay minerals) generally have fine particle size (< 5 microns) in their natural states or due to overgrinding and they display poor flotation kinetics, consequently having low flotation recovery. Secondly, the wettability difference on different particle basal planes influences the affinity for adsorptions of different types of chemicals such as collectors or macro-molecule. Common polyacrylamide (PAM) flocculants can be used to minimize the exposure of the most hydrophilic planes of clay particles via hydrogen bonding but they can not efficiently enhance the overall particle surface floatability due to the hydrophilic properties of this type of macromolecules. A novel method to improve both flotation kinetics and surface wettability of silicate minerals has been developed and studied. That is to use a temperature-sensitive polymer, poly (N-isopropyl acrylamide) (PNIPAM), as a process aid in the flotation of silicate minerals. Unlike PAM polymers, PNIPAM can induce a hydrophilic/hydrophobic transition on the particle surface when the temperature is changed to be lower or higher than its critical solution temperature (CST). At a lower temperature, the PNIPAM adsorbs on the particle surface via hydrogen bond similar to PAM. It induces strong hydrophobic aggregation when the temperature is increased above the CST. Thus, both floc size and mineral floatability are greatly increased. The flotation results show very good flotation performance and the addition of conventional flotation collector was no more required because the increased particle surface hydrophobicity induced by PNIPAM. Contact angle measurements explained the role of PNIPAM in manipulating particle surface hydrophilic/hydrophobic transition.

Jan 1, 2014

By Masakazu Niinae, Kenji Aoki

"Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals than at a lower pH and the precipitation of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient.In this study, the effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is examined. The complexing agent selected was ethylenediaminetetraacetic acid (EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and is successfully removed at the anode reservoir."

Jan 1, 2003

By M. Unesi, S. Haj Mohammadi, M. R. Abdoli, M. R. Garmsiri

"Hydrocyclone-thickener circuit is a promising solution to enhance the dewatering efficiency in mineral industries. The challenges in the circuit is reducing particle size in the thickener feed and the good feature is a rise in the retention time of sediments in the thickener. In this work, the effect of particle size, bed depth and residence time on the thickener performance were investigated. In this order, pilot scale columns were employed at Sarcheshmeh and Shahrebabak copper complexes. Furthermore, the influence of residence time was differentiated due to the variations in the bed depth and settling flux. Moreover, a new approach was introduced to estimate solids residence time in the thickener. results indicated that with smaller particles that are introduced to the column, the bed density as well as thickener discharge solids concentration dropped significantly. It was found that thickener discharge solids concentration fell from 59.6 to 33.8 % with reducing particle size from 130 to 22 µm in the settling flux of 20 t/m2/day. Additionally, it was found that longer residence time and deeper bed resulted in an increase in the thickener performance while the bed depth has a stronger effect. It was proved that employing a hydrocyclone prior to the thickener resuted in an increase in the dewatering efficiency.INTRODUCTION Thickeners are widely employed in mineral industries to recycle tailings and concentrate water content. A limited fraction of suspension water content is recycled using a thickener. For instance, about 50 percent of tailings water content could be recycled using a shallow bed thickener during copper processing. Since the scarcity of global water resources became more serious, the demand for improving dewatering efficiency in mineral industries became more significant [1]. A number of solutions were recommended to enhance dewatering efficiency of thickeners including optimization of current thickeners, employing deep bed thickeners and utilizing thickener-filter or hydrocyclone-thickener circuits. Optimization of existing thickeners is essential, however, it does not meet the significant demand for recycled water. The application of deep bed thickeners (known as paste thickeners) has been rising in the mineral industries [2] due to a higher dewatering efficiency while its costs is remarkable."

Jan 1, 2018

By Stefaan J. R. Simons, Michael T. Spyridopoulos

In this paper the effect of humic substances (natural surfactants), electrolytes and solid particles on bubble coalescence, and as a consequence on froth stability, has been investigated. We formed two bubbles of equal size and forced them to collide using a novel experimental apparatus. The interactions were recorded by a high-speed camera, the images of which helped to determine the coalescence frequency and the coalescence time, as well as the mechanisms of the interactions. Two types of humic substances were used, along with three different electrolytes. Humic substances appeared to have a considerable effect on bubble coalescence, while the effect of electrolytes was minimal. Moderate and high hydrophobic glass spheres were used between two bubbles. Very hydrophobic spheres promoted fast bubble coalescence, while moderate hydrophobic spheres had no effect. We present data of coalescence frequency and time, as well as images of the coalescence events.

Jan 1, 2003

By Ali Dehghani Ahmadabadi

Gravity separation technique is widely used in mineral beneficiation practices for its low cost, ease of operation, and eco-friendly nature. The most commonly used gravity methods for beneficiation of iron ores are shaking table, jig and spiral methods which aren&apos;t very effective for iron mineral fines. Multi-Gravity Separator (MGS) is suitable for the treatment of fines with a maximum particle size of approximately 500 µm. This study was performed on a low-grade haematite iron ore from Chadormalutailing dams. Detailed mineralogical, physical and chemical characteristics of a goethiticlateritic iron ore showed that the sample contained porous and friable oxides and hydroxides of iron. The ore sample had a feed grade of 35% Fe, 1.1% FeO, 15.5% SiO2 and 8.5% Al2O3. Haematite and goethite are the main iron-bearing minerals while quartzite and kaolinite are the major gangue mineral constituents. In this paper, the statistical evaluation and optimization of grade and recovery using a factorial design of experiment (DOE) method has been carried out for Chadormalulow grade ultra-fine haematite tailings with MGS. The input process parameters considered are drum speed, tilt angle, wash water flow rate and pulp density. The results show considerable improvements in both the quality characteristics such as grade and recovery with statistical evaluation and optimization, compared to the initial value of grade and recovery. Keywords: multi-gravity separator, mgs, statistical evaluation, optimization, haematite

Sep 1, 2012

By József Faitli, Barnabás Csoke, Károly Solymár, Zoltán Hatvani, Dimitri Papanastassiou

"Grinding has a significant economic impact on ore dressing/processing, therefore the sizing of mills has an outstanding role.In most cases, the sizing of dry or wet mills for ore processing is primarily based on the determination of the Bond grindability index, using the Bond-Kjos-Rowland relations. In several cases, grinding takes place under conditions different from these and the grinding conditions have a great influence on the post-grinding process. This is particularly true for the grinding of bauxites where grinding takes place in alkali, often in higher temperature (up to 100 ºC) in alkali Liquor. So it is necessary to develop a testing method providing a reliable grindability index even under these special circumstances (grinding in alkalis medium at different temperatures) and allowing a more precise mill sizing. The new heated mill is suitable to determine the grindability index under temperature-controlled circumstances, in liquids with different temperatures (water, alkali). This paper presents in detail the equipment, the conditions (parameters) of the testing process for wet and alkaline grinding, the measuring results and the conclusions."

Jan 1, 2003

By Brian Hart, Liuyin Xia, Staman Dimov

The recovery of rare earth elements (REE) is fast becoming of significant interest globally. Modern research and development programs (outside China) towards the optimization of REE mineral recovery by flotation have been lacking. Due to the mineralogical nature of many hosting deposits, the separation and recovery flotation flowsheets can be very complex. As part of a research project, a selected suite of hydroxamic acid collectors (Naphthoyl, Cyclohexyl, Benzoyl, Octyl, Terta-butyl benzoyl, Salicylic) were tested in order to examine their potential for recovery and selectivity. Micro flotation tests were conducted on a feed sample, recovery and grade of the products were used to evaluate their relative flotation efficiency and selectivity and these results (flotation with the hydroxamate collectors) were compared to a phosphoric acid/sulphonate collector mix(shorten as "mixed"). In the testing, the flotation response with the hydroxamate collectors was significantly better than the "mixed" collectors on freshly ground (no slimes removed) samples. Furthermore the tests revealed that for most of the hydroxamate reagents tested, their dosage requirements to achieve recoveries at the same levels was less than that for the "mixed" reagents. Product assays show that recovery of both La and Ce is significantly better for using the salicylic hydroxamate and that Nb, Y and Zr recovery are favored by using octyl hydroxamate. These results indicate mineral flotation selectivity could be achieved by using selective hydroxamtes. Spectral fingerprinting by TOF-SIMS surface analysis has allowed for the identification of reagent species. TOF-SIMS surface analyses of grains analysis confirmed that REE bearing grains reporting to the concentrates are doing so in response to collector attachment whereas grains reporting to the tails are doing so in response to a lack of collector. The TOF-SIMS surface data bas been used to examine the factors promoting flotation stream partitioning.

Jan 1, 2014

By K. V. Fedotov, G. I. Sarapulova

The study is devoted to the earth's surface protection and is aimed at improving the ecological safety of the territories in the mining industry. Identification of the diagnostic signs and quantitative criteria for the disturbance of soil geochemical properties and water chemistry represent an important scientific task in anthropogenically disturbed landscapes in the context of comprehensive exploitation of mineral resources. The study is aimed at geological and ecological analysis of the migration peculiarities of the man-caused chemicals and elements in soils and soil-surface water environment. We received new results. These results assist in estimating the peculiar features of distribution of heavy metals total and mobile forms (Cu, Ni, Zn, Pb), depending on the physical and chemical parameters of the disturbed soils. We obtained the empirical relationships describing heavy metals localization and accumulation processes depending on buffer properties of soils (pH, N, Corg), salinization factor and contamination with oil products. Anthropogenic geochemical barriers spontaneously formed in the area of industrial facilities were revealed in the territories of industrial facilities. These barriers prevent the further distribution of elements and pollutants in the landscapes. This makes it possible to create their artificial analogues in order to limit further migration of pollutants and to immobilize valuable components. Analysis of diagnostic features of soils geoecological state and factors influencing the distribution of heavy metals in the soil-surface water geosystem allows the identification of the geochemical barrier type with the aim of elements immobilization in a limited area of the territory. We applied modern physical and chemical methods of analysis, a package of statistics programs in Excel and modeling techniques. The proposed approach is innovative and therefore can be attractive. The accumulation of useful components losses in mineral resources exploitation is a promising reserve for their recovery from the soil with specifically arranged properties. The methodology of this research is also promising for the prediction of the environmental emergencies of the anthropogenic nature. This is consistent with the requirements of state control of environmental safety in the course of comprehensive exploitation of mineral resources.

Jan 1, 2018

By M. Eraydin

Dewatering fine particles (e.g., flotation concentrates) is inefficient, energy intensive and often requires large capital and operating costs. To address these issues, a series of advanced dewatering technologies have been developed at Virginia Tech. These include novel dewatering aids and a hyperbaric centrifuge. Typically, the moistures obtained using these methods are 30% to 50% lower than those obtained using conventional methods, as demonstrated in laboratory and pilot-scale test programs. With another novel dewatering technology that has been tested in bench-scale tests, the moistures can be reduced to levels once believed to be attainable only through the use of thermal dryers. In this communication, test results obtained with these advanced dewatering technologies are presented and compared.

Jan 1, 2014

By Jim Pae Lem

This study investigates the mode of occurrence of uranium in a copper concentrate from the Prominent Hill mine. Mineralogical and liberation studies of a high grade Cu concentrate (monthly composite) containing uranium (U) were undertaken using QEM-Scan in combination with QXRD and ICP-MS. The study aimed at determining in what form U was recovered, and by which mechanisms. The deportment of U was studied in 3 size fractions; +20µm, -20+8µm and -8µm. QEM-Scan analysis showed that uranium was present as U(Cu)-silicates, U-silicates, UPbOx/FeOx or traces of UThOx and UTiOx, with the U-silicates present across the size fractions. The association of uranium bearing minerals with copper sulphides varied across the size ranges. Interestingly, most of the U (46% by weight) was distributed in the finest fraction (-8µm), in which the deportment of Cu was low (6%). Over 40% of the U mineralisation in the -8µm was liberated. In terms of the floatation response, while recovery of the uranium minerals as a result of their association with copper sulphides (as composite particles) was evident, recovery of UPbOx locked in hydrophilic haematite in the +20µm size fraction suggests, that other mechanisms (e.g. Inadvertent activation by Pb from radioactive U decay) are possible. Furthermore, the high amount of fine liberated U bearing particles in the concentrate points at entrainment as another major mechanism for uranium recovery, and therefore, a target for process optimisation.

Sep 1, 2012

By P. T. L. Koh

The effect of particle shape on the flotation process has been investigated in laboratory experiments with monosized spherical ballotini and roughly ground ballotini. The particles were treated by partial methylation with trimethylchlorosilane to achieve varying degrees of hydrophobicity. In flotation, the process of film thinning and liquid drainage is critical in the formation of a stable bubble-particle attachment and this is affected by the particle shape and surface hydrophobicity. The rate of attachment affects the overall flotation rate. Flotation tests with different particle sizes at various degrees of partial methylation have been performed in a modified Denver cell. Predictions from a computational fluid dynamic model of the cell which incorporates fundamental aspects of bubble-particle attachment are compared against flotation test results. Contact angles of the particles have also been measured using the capillary rise technique to indicate surface hydrophobicity.

Jan 1, 2014

By de Vaux. Deryck, Natalie J. Shackleton, Vratislav Malysiak Cyril T. O. Connor

"The major losses of PGM and base metals in the beneficiation of platinum group deposits occur during the separation of gangue from the value minerals by selective flotation. A number of studies have shown that this negative impact on flotation is due to surface passivation, caused by various ions that may originate from the external water supply or, as is likely in the majority of cases, from the oxidation of the mineral surfaces and the grinding media. This investigation aimed at reducing surface passivation of pentlandite and inadvertent activation of pyroxene, thereby improving ultimate valuable mineral recovery and selectivity. Both synthetic minerals and plant ores were studied in order to determine the effect surface passivation and inadvertent activation have on mineral surface alteration and floatability. Zeta potential determinations, microflotation, ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) analyses, laboratory batch flotation tests and continuous flotation testwork were used as tools to study the surface alteration and/or floatability.Zeta potential determinations and ToF-SIMS analyses showed that copper adsorption is non-selective. Both pentlandite and pyroxene become copper (II)-activated in the presence of copper sulphate and subsequently, in the presence of xanthate, adsorption of the collector will occur onto copper activated mineral surfaces. Zeta potential determinations also showed an alteration of the surface charge in the presence of polyphosphate, thereby inhibiting surface passivation of sulphides by slime coatings due to surface repulsion.The addition of diethylenetriamine (DETA) reduces the copper concentration on both minerals, predominantly on the pyroxene surfaces and polyphosphate further enhances the selectivity at pH 6.The microflotation and batch flotation data obtained has shown a significant improvement in the ultimate flotation response of valuable mineral recovery and concentrate grade compared to the standard reagent regime, while the continuous flotation results significantly improved the selectivity, however, at a similar ultimate recovery."

Jan 1, 2003

By A. Collings, A. Farmer

Power ultrasound may be used in the processing of mineral suspensions to clean the particle surfaces of oxidation products and fine coatings, mainly through the large, but very localised forces, produced by cavitation. This effect may be utilised in lowering the level of iron contamination in silica sand used for glass making, in improving the sharpness of electrostatic separation of heavy mineral concentrates, in shortening the time of leaching of minerals and in improving the selectivity and recovery of flotation processes. Parameters affecting the efficiency of these processes, such as input power and levels of reagent addition, are discussed. In particular, we present data showing the relationship between power input and the particle size of surface coatings removed, which can be explained by the Derjaguin approximation for the energy of interaction between a sphere and a flat surface. Pilot scale studies, using commercially available components, are currently being used to assess process viability and will be compared with laboratory scale results.

Jan 1, 2003

By F. M. Zafar Kaifi

Magnesite producing companies rely on high grade purity MgO. The mineralogy of magnesite has a significant impact on the manufacturing of magnesite bricks. The manufacturing process of bricks companies utilizes 90% magnesite from 85%~90% MgO. The main objective of the magnesite bricks was to utilizes the indigenous raw material available in bulk quantity. With better under-standing of chemistry of the mineral species and strict control of bricks manufacturing/processing conditions can be better produce efficiently, a low cost high quality bricks with minimum detrimental environmental impact.

Jan 1, 2014

The flotation of nickel sulphide minerals is normally difficult in the presence of serpentine minerals due to the coating of serpentine particles on the nickel mineral surface. To improve the flotation, dispersants such as polyphosphate and carboxy methyl cellulose are normally used to remove the slime coating. However, in the flotation using high ionic strength process water, these dispersants are invalid due to their ionic nature. In this study, a new type of non-ionic dispersants, Pluronic triblock copolymers were examined with an objective of improving the flotation of ultrafine pentlandite (a nickel sulphide mineral) in the presence of lizardite (a serpentine mineral) in saline water. Three Pluronic triblock copolymers varying in solubility and hydrophile-lipophile balance (HLB) values were studied by flotation tests, settling tests and froth measurement. It was found that two of the copolymers improved pentlandite flotation against lizardite, and one copolymer deteriorated the flotation. The effect of Pluronic triblock copolymers on the flotation was actually linked to their dispersibility and foamability, which were governed by their physical properties. The two copolymers with a higher solubility or HLB value produced more stable mineral suspensions and more stable froth in the flotation resulting in better nickel grade and recovery in both rougher and cleaner flotation. Keywords: ultrafine particle, flotation, slime coating, dispersion, saline water, triblock copolymers

Sep 1, 2012

By Robert Peretti, Antonio Zucca, Andrea Manni, Silvia Serranti, Paolo Massacci, Marcello Ghiani

"This research study aims to identify the best way of processing colemanite concentrates, which is sometimes characterised by a high content of As sulphides, finely disseminated in the matrix of the boron mineral.Scanning Electron Microscopy analyses have been carried out to identify all the mineralogical constituents and to evaluate their distribution, frequency and mutual relationships.Colemanite concentrates are mainly used by chemical plants producing boric acid and gypsum. A high As content is unacceptable for further use of tailings coming from the leaching process and is very dangerous if the tailings are released into the environment.Grinding tests were conducted under dry and wet conditions in order to assess how As sulphide minerals are released from colemanite minerals.Some of the difficulties involved in obtaining selective liberation of As sulphides from colemanite minerals were overcome, although a certain decrease in As grade in the higher size classes was registered.All comminution products have been analysed by SEM, monitoring the degree of liberation of the mineralogical constituents.Flotation tests have been carried out, following different comminution flow sheets and adopting different modulating conditions in order to evaluate the influence of the following parameters:- collector concentration versus contaminants concentration (As minerals) in the froths;- kind and quantity of the frothing agent to maximise mineral recovery in the froths;- kind and quantity of the modulating agents to maximise the selectivity of the process;- conditioning modalities in order to obtain a suitable dispersion of fines and avoid segregation of Asbearing particles together with colemanite ones;- solid/liquid ratio of the pulp to minimise the water flow into the plant.Information obtained from SEM analysis has been adopted to evaluate segregation phenomena in pulp and in flotation products."

Jan 1, 2003