Search Documents

Ca-containing gangue minerals such as Fluorite, Calcite have same surface activity point--calcium ions and approximate floatability with scheelite, it is difficult to achieve good dressing index of rough concentrate of scheelite. Mono-mineral experiments and ore tests indicate that, according to mineral composition, gangue minerals can be inhibited selectively by adopting suitable regulators, then the separation of scheelite from gangue minerals can be realized effectively. Mechanism analysis was taken by zeta potentials measurements and FTIR tests. Good dressing indexes are also obtained in practical ore tests and industrial tests. Keywords: scheelite, fluorite, calcite, regulator, flotation separation

Sep 1, 2012

By B. Peszko

There are many measuring methods of grain sizes. Taking into consideration the fine grained materials, one of the existing techniques is measurement of grain size by the Coulter Counter method. This method is based on the measuring the changes of electrolyte resistance during grains flow through the calibrated diaphragm. This method is relatively simple to apply, significantly precise and the results are given quickly. However, the problem is that the measurements are limited by the size of diaphragm. Because of this situation, measurement of grain sizes by this instrument is possible in range from 10% to 60% of diaphragm diameter. This limitation causes the necessity of re-placing diaphragm in case when the measured grain size distribution concerns the material of large size range. In purpose of determining the total grain size distribution, the synthesis of some partial distributions, given for individual grain fractions (with different diaphragm applied), is required. This is possible to do by calculating the mixture of distribution functions, created from the partial distribution functions. Two materials were selected to research: quartzite and glass, which were comminuted in cylindrical crusher, additionally grinded, screened and then analyzed by Coulter Counter for five grain fractions: 0~125 µm, 0~80 µm, 0~56 µm, 0~40 µm and 0~25 µm. For each fraction, five different partial distributions were given (in case of glass ? four), which are the basis for the creating the joined grain composition. To assure the adequacy of the given distribution function, it is necessary to obtain the possibly best approximation of partial distributions. In the work, both the parametric and non-parametric methods of density approximations of investigated random variable. For each grain fraction the approximations were done by three traditional distribution functions: RRB, GSA and log-norm distribution functions and three methods of non-parametric approximation: Gauss kernel, Epanechnikov kernel and orthogonal Fourier series method. As the criterion of the certain distribution function acceptance, the value of the residual deviation was assumed, given by the formulae:

Jan 1, 2014

By V. V. Ramarao

Grinding and flotation operations deliver better-optimized performance when they are monitored and controlled in terms of the minerals they process rather than as elemental assays that we usually refer to. Mesh of grind (MoG), liberation, floatability, grade and recovery etc. are more directly related with the minerals and their characteristics rather than the elemental assays. Hence, online analyzers only provide the status for the grade and recovery of metals and not the direction for the enhanced performance. Central Research and Development Laboratory (CRDL) and Rampura Agucha Mine (RAM) mill section of Hindustan Zinc Limited (HZL) jointly undertook various survey campaigns in the grinding and flotation process streams. Grinding circuit surveys involved systematic collection of representative samples from different grinding circuit streams under stabilized conditions for monitoring particle size and process mineralogy details across individual grinding circuit. Flotation survey campaigns included study of fort-nightly / monthly composites of un-ground flotation feed, lead concentrate, lead tailing, zinc concentrate and final tailing samples for size distribution details in the 150 ? 38 micron range, chemical analysis and mineral characterization through optical microscope. This work details the investigations results and their implications on beneficiation performance. Grinding circuit survey campaigns supported the task for modifying the originally installed configuration of hydrocyclones, to limit recovery losses due to excess grinding of soft galena and related silver minerals. Flotation plant surveys helped in adjusting flotation circuit process parameters to reduce loss of liberated and floatable galena and sphalerite grains into their respective tailing streams. Keywords: grinding circuits, survey campaign, hydrocyclones, mineral liberation and locking, lead-zinc ore beneficiation operation

Sep 1, 2012

By C. Dorfling, W. A. Rossouw

"Hydrometallurgical processes used for metal recovery from waste printed circuit boards (PCBs) typically involve dismantling, shredding and physical separation prior to successive leaching stages for selective dissolution of different metals. The principles of the physical separation units are well understood, but valuable metal losses of more than 30 % can be incurred during these processing steps. The impact of the physical separation units’ performance on downstream leaching operations have not been defined; this prevents the development of a well-integrated process. The objective of this project was to determine to what extent the base metal leaching behavior depends on the physical separation pre-treatment. PCBs were shredded to 100 % passing 2 mm before physical separation by dense medium separation (DMS) as well as magnetic separation. Batch leaching tests using various concentrations of sulfuric acid were conducted on three feed fractions: (1) shredded PCBs without any physical separation, (2) heavy fraction recovered from DMS, and (3) non-magnetic fraction recovered from the DMS heavy fraction. DMS increased the metal content in the feed from 48 % to 75 % on a mass basis, but 70 % of the gold and 20 % of the copper reported to the light fraction. The application of magnetic separation to the heavy fraction produced by DMS removed 67 % and 61 % of the iron and nickel, respectively, while negligible amounts of non-magnetic metals were removed. Although DMS successfully concentrated the feed and magnetic separation removed the majority of iron and nickel, these steps did not result in any improvement in the rate or extent of copper leaching. Metals generally leached faster when the sulfuric acid concentration was increased from 1 M to 2.5 M; this effect was seen to be more pronounced for pretreated feed. INTRODUCTION The fast rate of technological development has led to a decrease in the service life of electronic devices. This is resulting in an increased rate of electronic waste generation. The recovery of metals from electronic waste is of environmental and economic interest. The majority of these metals are typically located on printed circuit boards (PCBs) within electronic devices (Tuncuk, Stazi et al., 2012). Hydrometallurgical processes are considered a viable option for small scale metal recovery from waste PCBs, and generally involve the following steps: disassembly for removal of hazardous and reusable parts, size reduction, physical separation, successive leaching stages for metal dissolution and finally recovery of metals from leach solutions."

Jan 1, 2018

By M. Bhartia

India is the 5th largest producer of steel in the world and is slated to produce more than 180 Mt by 2020. Expectedly about 50 % of this would be through the Blast furnace route and the rest through Sponge iron / DRI route. Considering that there will not be any major change in iron making technology by that time, the Blast operation would require lump ore (10-40mm) with around 64% Fe grade and sinter fines (<10mm) with 60% Fe (min) as its feed. DRI process would need calibrated ore of size 5-18 mm as the most suitable size of feed. It is also expected that of the total requirement of ore for the DRI route a significant part would be DRI pellets. In India, there is considerable debate going on regarding the technology to be adopted for the processing of iron ore and there is a lack of clear consensus. The above scenario indicates that the processing requirement of iron ore in the country would involve both washing technology as well as beneficiation technology. CDE Asia Ltd is in the forefront of iron ore processing in the country and the experience gained by the company over the last few years of functioning has led the company to believe that route to be adopted depends on the end product requirement and the starting grade of the feed. Keeping in mind the nature of the feed required for the Blast furnace & DRI operation; it is obvious that good washing technology would be highly beneficial to the iron ore industry. Depending on the grade of ore available the limits of washing will be decided and equipment for lump ore beneficiation such as jigs could be incorporated into the washing circuit. Scrubbing of ore either before washing or selectively scrubbing the lumps could be necessary. Very low grade ore and jig rejects would be required to be totally ground and beneficiated for the production of pellet feed in order to utilize the iron ore resources entirely. Another source of ore for pelletisation would be slimes generated from the washing process as well as the huge quantities already available in the tailings dams in the operating mines. Deslimimg and magnetic route of beneficiation could release at 30-40% of the Fe locked up in these tailings ponds/dams. The paper describes the concept with examples from operating plants and proposes how the adoption could be engineered through test work and proper plan of integration. Keywords: washing, beneficiation, iron ore, lumps, sinter fines, pellets, jigs, screens, evowash, nanowash, thickeners, log washers, drum scrubbers

Sep 1, 2012

By A. Singh, M. Ntlhane, V. Ross, M. Dlame

"Fine valuable particles are often lost to flotation tailings streams due to inefficient collection by air bubbles as well as passivation of surfaces by oxidation and slimes. The application of high-shear hydrodynamic cavitation devices (HCDs) to overcome this problem has already proven to be a considerable success in the industry. This paper details the results of further investigations that were undertaken at Mintek to better understand the mechanisms involved when preconditioning feed slurries in an HCD. By promoting inter-particle attrition and conditions of high shear within the reactor, cleaning of particle surfaces is enhanced as well as the formation of superfine (nano) bubbles which are believed to aid their agglomeration and subsequent collection by normal sized bubbles. In order to broaden the envelope of understanding with regard to application of the technology, rather than tailings material as investigated earlier, a Platinum Group Mineral (PGM) UG2 ore from the Bushveld Complex in South Africa was used in this study. The results of a series of batch flotation tests in a 10L Denver cell are presented, being conducted after the feed has been subjected to different methods of preconditioning. It was demonstrated that the preconditioning significantly improved the flotation kinetics of the PGMs, the optimum being obtained after around 20 passes through the reactor. This was accompanied by a much enhanced recovery-mass pull relationship and a significant improvement in the grade-recovery response. Significantly, the selectivity between the PGM and the deleterious chromite (expressed as Cr2O3) gangue more than doubled under these conditions. Modelling of the PGM data by means of the modified Kelsall model indicated that both the fast and slow floating rate constants were improved.INTRODUCTIONIt is well known that the flotation recovery of fine and ultrafine particles, typically less than 10 micron in size, is a challenge (Yoon et al., 1989; Miettenin et al., 2010). Although these particles are typically well liberated, due to their very low mass and inertia, the collision efficiency with air bubbles is low as a result of the inability of particles to penetrate the liquid streamlines around bubbles. Hence the probability of contact is often regarded as the ratedetermining step in flotation of ultrafine particles. Introducing more power into conventional flotation machines is likely to solve only part of the problem, as conventional mechanisms are effective only to a point in terms of shear and micro-turbulence. Further challenges are posed by the treatment of low-grade or oxidised tailings dump material, where valuables are passivated due to prolonged exposure to the atmosphere or slimes. Over the years, various mitigating strategies have been investigated, including the use of dissolved air flotation (Martinez-Gomez et al., 2013; Calgaroto et al., 2015), shear flocculation (Subrahmanyam and Forssberg, 1990), seed or carrier flotation (Tabosa and Rubio, 2010), sonication to clean particle surfaces (Aldrich and Feng, 1999; Newell et al., 2006), high intensity conditioning (Bulatovic and Salter, 1989; Chen et al., 1999; Tabosa and Rubio, 2010), and various electrochemical approaches such as changing Eh in order to promote formation of dixanthogen, dissolution of oxidation products by lowering the pH, activation by sulphidisation (Newell et al., 2006; Becker et al., 2014), and the use of alternative collectors."

Jan 1, 2018

By K. Haga

In this study, flotation tests were performed to investigate behavior of enargite and chalcopyrite ores from different sources synthetically mixed for separation of enargite. Flotation parameters including; pH, reagents concentration and type and flotation time were controlled to obtain an enargite concentrate with high As and chalcopyrite concentrate and final tailings with As content below 0.5 mass%. The copper ore bearing enargite mineral contained 5.87 mass% As and 16.50 mass% Cu while the chalcopyrite bearing ore contained 0.32 mass% As and 21.63 mass% Cu. The two ore samples were mixed at 7:3 (enargite: chalcopyrite) by weight ratio to prepare a mixed ore sample with arsenic content at 3.16 mass% and 18.25 mass% Cu for the flotation study. For enargite single ore flotation, the 38?75 µm size fraction showed that over 98% enargite was selectively recovered within 5 min at slurry pH of 4.0 and arsenic content in the final tailings was reduced to 0.22 mass%. In mix ore (enargite+chalcopyrite) flotation, 97% of enargite was first removed at pH 4 followed by chalcopyrite flotation at pH 8, and over 95% recovery was achieved in 15 min flotation time. Arsenic content in the final tailings was reduced to 0.1 mass%.

Sep 1, 2012

By O. Kökkilic

This study covers the tests to develop separation process for production of clay and colemanite rich concentrates, and aims to serve the clay and colemanite concentrates extracted from the tailing dams to the industrial applications. For this purpose, samples from the tailing dams in Kestelek Boron Plant (Turkey) with an average B2O3 content of 8%~11 % were subjected to the investigations. The separation process of hydrocyclone--to make clear the way to obtain either clean clay or cole-manite--was initially discussed. Therefore, following the gentle scrubbing (to keep the bimodal size distribution between clay and colemanite) of the tailings to disperse the slurry, two alternative multistage hydrocyclone processes; allowing to recycling the overflows or underflows to concentrate clay and colemanite were respectively tested. As a result of the preliminary tests, the multistage hydrocyclone separation in direction to the clean colemanite concentrates (recycling the underflows) gave the better separation efficiencies. So, all the parameters such as apex and vortex finder diameters and feeding pressures were examined with the multistage hydrocyclone process allowing the recycling the underflows. The detailed multistage hydrocyclone separation process of the tailing dam wastes yielded with colemanite concentrates (approx. 12 % of the feed, w/w) with B2O3 content of 35.0 % and the clay concentrates (approx. 42 % of the feed, w/w) with B2O3 content of 2.1 %. Colemanite concentrates were found good enough either to re-feed in to the separation process or to keep upgrading for final product ready to use in Industry whereas the attempts on production of light bricks from clay concentrates has failed. But it is worth to point out that these clay concentrates can be used for agricultural purposes just in the form as it is.

Jan 1, 2014

By A. Pirson, J. Souza, A. Araujo, M. Barbosa, F. Guimarães, J. Lima

"Although a large number of processes have been developed and applied to the separation of barite from other minerals, there is a lack of information in the literature about the separation of barite from iron ores. Nowadays, there are millions of tonnes of iron ore disposed as a waste or tailings given its high content of sulphur in the form of barite. In order to effectively separate barite from iron ore and ensure that mining business is truly creating economic and sustainable values, this paper provides a greater understanding of barite properties, the origin and occurrence of this barium-bearing mineral, and the employed beneficiation processes. A test work is conducted in a barite bearing iron ore from a deposit located in the Republika Srpska (Bosnia and Herzegovina) in order to separate the barite and check if a marketable by-product can be produced by drawing upon rich barite tailings. INTRODUCTION The exploration of iron ore containing barite results in a large amount of unrecovered material. The main difficulty in processing and using barite bearing iron ores is given by their high content of sulphur, silica and barium, which are unwanted chemical compounds in the subsequent processes in iron industry. As a result, millions of tonnes of iron ore are discarded every year into tailings or as a waste, which results in production losses, higher operation costs and environmental impacts (Praes et al. 2013). Therefore, the separation of barite from iron ores not only means reducing the environmental impact, but also an opportunity to generate income and beneficiate society. The beneficiation of barite bearing iron ores is a subject which requires a deeper investigation to solve the challenges faced by the iron industry. There are only a few studies that describe flowsheets proposed for the production of barite concentrate of iron ores. The most likely reason for this gap is that barite is frequently exploited commercially as a primary product rather than a by-product. In order to effectively separate barite from iron ore and ensure that mining business is truly creating economic and sustainable values, this paper provides a greater understanding of barite properties, the origin and occurrence of this barium-bearing mineral, and the employed beneficiation processes. A test work is conducted in a barite bearing iron ore from a deposit located in the Republika Srpska (Bosnia and Herzegovina) in order to separate the barite and verify if a marketable by-product can be produced by drawing upon rich barite tailings."

Jan 1, 2018

By E. Burdukova

This paper explores the relationship between the rheological behaviour and mineralogical nature of three different natural ore types. Rheological measurements performed here on Platreef, Kimber-lite and Norseman-Wiluna ores are correlated with the variation of phylosilicate mineral content in these ores and the corresponding physical properties of selected phylosilicate mineral groups. Preliminary results show that the clay mineral group (talc) has the least effect on both Bingham yield stress and viscosity of the three ore slurries tested, whereas the serpentine mineral group has a dramatic increasing effect on the Bingham yield stress especially at very low solid volume fractions. The Bingham viscosity of the mineral slurry appears to be the most influenced by the presence of the swelling clay mineral group (smectite). Significant increases in either Bingham yield stress or viscosity due to elevated contents of these problematic phylosilicate mineral groups are likely to cause negative effects on the processing and manageability of mineral slurries but it is unclear which is likely to have a more detrimental effect.

Jan 1, 2014

By K. S. McClure, S. B. Chitralekha, R. B. Gopaluni, Chmylek. T., S. L. Shah

This is a tutorial paper on industrially successful approaches for nonlinear process monitoring. Online process monitoring is essential to continuous operation of plants at high efficiency. The problem of process monitoring is one where an impending but undesirable process condition has to be identified and used to alert process engineers. This problem has traditionally been solved by practicing engineers using statistical techniques that detect a change in the underlying correlation structure of process variables. For linear correlation structures, algorithms such as principal components analysis, independent component analysis and partial least squares have been proposed. However, many industrial processes exhibit nonlinear correlation structure between the process variables. In this tutorial we describe various nonlinear monitoring techniques and elaborate on two recently developed methods, namely Support Vector Machine and Local Linear Embedding. The two methods are evaluated by application on two experimental case studies, a SAG mill and a polymer extruder.

Jan 1, 2014

By J. Y. ` Xie

The paper introduced bio-oxidation plants of refractory gold concentrate in China and CCGRI cultures. CCGRI cultures are composed of bacteria and archaea. Archaea Ferroplasma acidiphilum is very thick and fills whole mineral surface. It plays a more dominant role in CCGRI process. Several years of practice has proved that the operating temperature in bioreactors between 38~52?,gold recovery is almost same. Pulp concentration has been increased each year and reached to 25%.

Jan 1, 2014

By S. Vimalnath

The bioremediation capability of Pseudomonas aeruginosa cells was investigated for the biosorption of lead ions from aqueous solution. The various parameters such as pH, kinetics, biomass loading and concentration of lead affecting the biosorption process were studied. Complete bio removal of lead could be achieved for an initial concentration of 12.4 mg/L at pH 6.2, corresponding to typical industrial effluents. The biosorption isotherm followed Langmuirian behavior and the Gibbs free energy (?G) was determined to be-30.8 kJ/mole, indicative of chemisorption between the functional groups of the bacterial surface and lead. The biosorption kinetics adhered to a pseudo-second order model. The possible mechanisms of interaction of lead with the bacterial cells are discussed. A carbon paste electrode with a coating of biomass was developed for lead ion detection in aqueous solution using cyclic voltammetric technique. Concentrations of lead up to 5x10-5 M could be successfully detected using cyclic voltammetry, which could be improved to a detection limit of 1x10-8 M adopting differential pulse anodic stripping voltammetry (DPASV). Keywords: Pseudomonas aeruginosa, bioremediation, lead, voltammetry

Sep 1, 2012

By L. Ya Agapova

Emissions from pyrometallurgical processing of copper concentrates are usually subjected to wet scrubbing. The washing sulphuric acid so produced contains up to 0.2 g/L of rhenium, which is recovered by solvent extraction in the form of crude ammonia permeate (NH4ReO4). The mother liquor, obtained from the sulfuric acid wash, contains up to 35 g/L of rhenium and significant amounts of impurities. Crude rhenium salt is commonly processed by double recrystallization to produce marketable salt. A ton of high grade NH4ReO4 can be produced using 3.0-3.5 m3 of mother liquor. We propose an efficient technology of mother liquor pre-treatment aimed at removal of water-soluble organics with subsequent electrodialysis. Electrodialysis of mother liquor in a multichamber electrodialyzer resulted in the production of pure rhenium acid, from which a marketable NH4ReO4 is precipitated using ammonia solution. Multiple steps of recycling consisting of dissolution of NH4ReO4 salt, rhenium acid production from NH4ReO4 salt by electrodialysis and precipitation of NH4ReO4 from rhenium acid made it possible to upgrade the purity of obtained rhenium compounds by 1-2 orders of magnitude. A rhenium metal powder of 99.997% purity was produced by high-temperature reduction of high-purity NH4ReO4 with gaseous hydrogen. Rhenium metal powder of high purity can be produced from sulfate solutions of NH4ReO4 by non-platinum anode-based membrane electrolysis processes also. Keywords: rhenium, mother liquors, membranes, electrodialysis, rhenium acid, ammonia perrhenate, reduction, powder, electrolysis

Sep 1, 2012

By D. Saramak

The comminution technology based on High-Pressure Grinding Rolls presses (HPGR) application is currently one of the most efficient methods of hard ore comminution from the scope of the energy consumption and the development of industrial HPGR applications in ore preparation circuits is presently the world trend. However, even though the technology is already in use in many countries, which are the leaders in application of modern mining technology, there is still lack of base investigations over the HPGR performance. Throughput and energetic models of HPGR performance are quite well developed, but technological models predicting the comminution effects still needs an in-depth research. In the paper authors present the method of modeling of HPGR products? particle size distribution with using of suitable mathematical models. A basis of the HPGR performance assessment and HPGR-based crushing circuits design is a product?s particle size distribution. In order to precisely determine the particle size distribution of a HPGR product, parameters of product?s particle size distributions should be conditional on the main technical parameters of the roller press like operating pressure and the speed of rolls. The most accurate approximation of a distribution of size particle d appeared the Weibull?s truncated distribution and it is possible to obtain significant relationships between the approximation formula and the value of operating pressure, or feed characteristics. It makes possible a determination of mass recoveries of the product?s respective size fractions and the productivity planning. Instead of pressure (P), the other HPGR operating parameters can be applied, but the P value appears to produce the most relevant relationship. Keywords: HPGR, comminution, particle size distribution, ore processing

Sep 1, 2012

By L. A. Cisternas, R. I. Jeldres, C. Cruz, P. A. Robles

"Previous studies have shown that the floatability of chalcopyrite in seawater at highly alkaline conditions is significantly affected by the presence of clays. The reason is that the species of calcium and magnesium present in seawater under those conditions may act as a bridge between the surfaces of clay and chalcopyrite, generating massive aggregates that then depress. In this context, the objective of this work is to analyze the impact of pretreated seawater with low amount of calcium and magnesium ions on the recovery of a sulphide copper mineral with high kaolinite content as clay. The seawater pre-treatment is done by the addition of sodium hydroxide in a high carbon dioxide environment. The chemical reactions realized under these conditions lead to the formation and precipitation of calcium and magnesium species that are subsequently removed by vacuum filtration. The pre-treated seawater is then used in flotation tests at pH 11 for copper sulphide, where the mineral is synthetically prepared by mixtures of chalcopyrite, kaolinite, and quartz. When comparing the flotation results for different types of water, including seawater and pre-treated seawater, a significant effect is observed: as the seawater hardness decreases, which comprises the calcium and magnesium ions, the recovery of chalcopyrite is increased. However, the effect is markedly enhanced in the presence of kaolinite. Therefore, the results indicate that sodium hydroxide and carbon dioxide are able to remove different species of calcium and magnesium from seawater and could improve the chalcopyrite recovery with high kaolinite content. INTRODUCTIONIn many cases, mineral deposits are found in arid areas with little access to water resources. Water is a fundamental element to carry out the unit operations that achieved the separation of valuable minerals (especially in concentration operations). Seawater has acquired an interesting role in recent years (Cisternas and Moreno, 2014); in fact, it seems to be one of the few viable options to ensure the sustainability of the mining industry in arid zones. At present, there are numerous experiences of industries that use or have used this resource, either by submitting the seawater to a desalination treatment by reverse osmosis or by applying it directly, without desalting. The latter case may involve significant economic benefits (for example, by avoiding the investment of building a desalination plant) and in some cases some operational benefits. A positive aspect is that in general terms the foaming in the saline medium is much more efficient compared to fresh water (Quinn et al., 2014; Castro et al., 2010). Some reports show that the foaming doses required to achieve a certain quality of bubbles are remarkably reduced, reaching exceptional cases such as Xstrata's Raglan concentrator, where it did not even include foaming to carry out the operation. This fact is quite promising, considering that some researchers have stated that controlling the quality of bubbles and foam could float minerals through coarse particles. This would lead to multiple benefits, such as energy savings by avoiding excessive grinding and a lower presence of fine ore that causes major problems in water recovery operations by gravitation (such as thickening) and in tailings management. However, seawater also causes significant challenges in multiple operations (Jeldres et al., 2017, 2016; Castro et al., 2010), as for example in minerals with high clay content (Uribe et al., 2017). In fresh water, the presence of clays minerals in ores is already a major problem in the flotation stages since the operation becomes difficult to be controlled, and operators are commonly forced to increase the consumption of reagents because the collectors are deposited on the clays' surfaces reducing froth stability (Farrokhpay and Bradshaw, 2012). Sometimes the use of rheology-modifying reagents should also be incorporated since the pulps become more visc"

Jan 1, 2018

By Linghu Changjin

Based on the characteristics of typical marine sedimentary phosphate rock in Guizhou, Southwest China, together with the research findings made on the surface electric properties of pure collophanites taken from different areas in pure water and under the action of collectors, a pure minerals flotation test of collophanite was conducted in this research. The differences of collophanite flotation behavior and the effects of the different pH values, varieties, and dosage of collector on flotation separation of collophanite were studied. It is suggested that that in pure water, collophanite had a negative charge within a wide pH range. The electro negativity values of collophanite increased with the addition of collectors GJBW and WF-01. When GJBW and WF-01 were used as collectors, the collophanite was depressed in acid medium, but had a good flotability in basic medium.

Sep 1, 2012

By Hillary Williams, Ronghao Li, Christopher Marion, Kristian E. Waters, Devin Hundt

"Zircon is an important mineral for ceramic, foundry, casting, and refractory applications; and it is the worlds primary source for zirconium. Zircon can also contain large and valuable proportions of other valuable metals, such as rare earth elements and hafnium. The Nechalcho deposit (Northwest Territories, Canad), is a hard rock REE deposit, which looks to recover zircon for its Zr and REE content. In this deposit, zircon is finely disseminated and associated with predominately silicate gangue minerals. Most of the work to date has focused on the beneficiation of mineral sand deposit, which typically remove silicate gangue minerals through physical separation steps. Therefore, the separation of zircon from silicate gangue, such as quartz, by flotation, has received little attention. This work used zeta potential measurements and microflotation experiments to understand the interaction between zircon and six different collectors (sodium oleate, sodium dodecyl sulphate, dodecylamine, SM 15, K-octyl hydroxamate and Florrea 7510). The results were compared with those of quartz. This study indicated that selective separation of zircon from quartz without the use of selective depressants or activators is likely challenging. The findings suggested sodium oleate and SM 15 only offered selective flotation of zircon in highly acidic conditions. Separation by the flotation of quartz is possible using sodium dodecyl sulphate, dodecylamine and K-octylhydroxamate. However, selective separation is highly dependant on collector dosage, for dodecylamine, and the selective activation of quartz, for sodium dodecyl sulphate and K-octyl hydroximate. Florrea 7510 offered poor recoveries for both zircon and quartz.INTRODUCTIONZircon (ZrSiO2) is a nesosilicate mineral which has a wide variety of applications, due to its hardness, opaqueness and resistance to heat and corrosion. Its major end uses are in ceramic, foundry, casting, and refractory applications (Bedinger, 2017). Zircon is also the most abundant zirconium (Zr) bearing mineral in the earths crust and is the principal economic source of Zr (primarily used in alloys for heat and corrosion resistance) and zirconia (ZrO2) (primarily used in ceramics) (Bedinger, 2017; Milnes and Fitzpatrick, 1989). Zircon forms in silicate melts and can often contain large proportions of other valuable metals such as rare earth elements (REE), and hafnium (zircon is the primary source of hafnium) (Bedinger, 2017; Belousova et al., 2002; Orlova, 2007). A common chemical formula showing the range of substitution in zircon is (Zr,Hf,Th,U,REE,Ca,Fe,Nb,Ta)(Si,P)O4 (Orlova, 2007)."

Jan 1, 2018

By I. Silin, H. Wotruba, J. Huben, A. Ognyanova

"With increasing shortage of raw materials, the beneficiation of ultra-fine ores will play a larger role in the near future. Many established process technologies do not yield satisfactory separation results for ultra-fine materials. Without selectivity, high-grade concentrates cannot be produced. The material at hand is a taconite which had to be ground to d(90) = 25 µm to guarantee liberation of the iron oxides. The comminution was done by High Pressure Grinding Roll (HPGR) and resulted in smooth surfaces and clear grain boundaries. This is an indication of selective grinding and mineral liberation. Further processing steps included selective desliming, magnetic separation as well as reverse flotation. INTRODUCTION During the last centuries, the processing of iron ores became increasingly important. The coarse-grained, so-called lump ores that are ready for direct usage in blast furnaces without further processing are becoming gradually less abundant. The processing of ultra-fine-grained ores, which in addition require a complex ore beneficiation due to the composition of the material, will progressively gain relevance with increasing resource shortages in the future (Arvidson, 2013). The term “ultra-fine” does not hold a precise definition in mineral processing. In this paper, “ultra-fine-grained” ores are defined by the required grind size for full liberation smaller than 20 µm. Many established mineral processing technologies do not yield satisfactory separation results for ultra-fine materials. Thus, they are limited in their application to produce high-grade concentrates suitable for sintering and pelletizing for direct reduction processes. The production of a high-grade iron concentrate (over 68% Fe) with low silica content (under 2.5% SiO2) is possible from both magnetite and hematite containing ore. In addition to the mineral processing technologies (magnetic and gravity separation, flotation), technologies for the liberation of fine-grained iron ores need to be developed and improved. In contrast to the conventional wet grinding circuit by means of tumbling mills, several future trends in dry and wet grinding and regrinding are already in use. These include technologies such as vibration mills (Palla®Mill), stirred media mills (Vertimill®), vertical roller mills (Loesche) and high-pressure grinding rolls (HPGR) (Jankovic, 2015). This study preliminary investigated the mineral processing of a low-grade, ultra-fine-grained, complex iron ore in a laboratory scale after dry grinding by HPGR to 90% < 25 µm without consideration of the grinding, milling, energy and classification cost."

Jan 1, 2018

By G. Mucsi

This paper deals with the laboratory investigation of cathode ray tube (CRT) glass based glass foam, a relatively new product so called ?Geofil bubbles?. The main process engineering material properties of raw materials, such as particle size distribution, moisture content, density and specific surface area are shown. Then the preparation of raw cathode ray tube glass waste is presented including the following steps: crushing in impact crusher, grinding in laboratory scale ball mill, mixing, pelleting and sintering. We found that it was possible to produce foam glass (with proper mechanical stability and particle density) from the investigated waste CRT glass. The material characteristics of the final product strongly depend on the sintering conditions. Optimum conditions were determined particle size fraction was found to be 4-6 mm, temperature 800 0C, residence time 7.5 min. Keywords: waste CRT glass, grinding, pelleting, sintering, glass foam

Sep 1, 2012