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By Anuj Narang

Large-scale separation or flotation cells, used in the primary extraction in the oil sands industry, are integral parts of the overall process of bitumen extraction. Good regulation of the interface level between the bitumen froth and the middlings in these cells can result in a significant improvement in bitumen recovery and throughput, and heavily influence process economics. Automatic control of such industrial processes presents challenges such as multi-phase flow dynamics, variable process gain and time delays, poor quality of measurements and significant disturbances. This paper details a case study application of development of multiple models of the dynamics of the interface level and the design of model predictive controllers (MPC) for a separation cell process. A Model predictive controller (MPC) using linear models is designed and implemented in real time on an industrial separation cell. The industrial implementation results show that the MPC scheme provides significant benefits over the current operations which use a PID controller. The benefits include significant reduction in the variance of the interface level resulting in higher bitumen recovery and smoother downstream operation plus energy savings due to reduced underflow pump speed.

Sep 1, 2012

By F. Ngoroma

Concentrators processing PGM bearing ores make use of polysaccharide depressants to reduce the recovery of the undesired naturally floatable gangue minerals, mainly silicates, present in the ore. Recent work has shown that high depressant dosages can completely depress naturally floatable gangue and thus prevent it from reporting to the concentrate. These high depressant dosages can, however, have a negative effect on the recovery of valuable minerals present in the ore by reducing the stability of the froth. In order to counterbalance the effects of depressant addition, frothers are added. It is, however, preferable to maintain independent control over bubble size and froth stability which is difficult to achieve with only one frother. An alternative strategy is, to use a blend of frothers, e.g. a weaker frother in combination with a stronger frother. Such a system allows an additional degree of freedom: changing the ratio of the two frothers, that would provide more independent control of bubble size and froth stability. This study demonstrates, through the use of batch flotation tests, how blending low molecular weight alcohols with commercially available frothers impact the solids and water recovery, as well as the valuable mineral recovery and concentrate grade in different PGM ores. Higher water and solids recoveries together with higher valuable mineral recoveries (>90% copper and >70% nickel) were obtained from tests using frother blends.

Sep 1, 2012

By S. Liu

With the development of global economy, the demand of mineral?s quantity and quality are in-creased, valuable minerals are more and more finer and poorer, and the capacity of concentration plant are more and more high. Using large-scale flotation cells can obviously enhance the capacity of treating the mineral, reduce the cost, and increase the economic benefit and competitive ability for the enterprise. BGRIMM advanced advisable technical scheme with optimally parameter and route for the feature of dynamic in large scale flotation machine, and developed the KYF Large Scale Flotation Cells, which have used more than 400. The paper advanced the history, the design principle, the operating principle, the structure feature and the application of KYF flotation ma-chine.

Jan 1, 2014

By S. Sarioglan

The bleaching of edible oils, industrial oils, and some chemicals may be achieved using natural and acid-activated clays. These materials remove impurities and pigments from the oils. In this work, a bentonite clay from Turkey (Somas bentonite) was activated with different concentration of H2SO4 and HCl at 70~90°C and 5~8 hours. Under these conditions several cations were removed from natural bentonite (Al, Mg, and Fe) and DTA-TGA, FT-IR curves of the solids obtained after acid treatment were examined. Treatment time and acid concentration increased the degree of destruction of the bentonite structure which was determined by ICP. Activated samples were tested in order to verify their capacity to bleach soybean oil and compared to standard commercial bleaching clays. The experimental results indicate that treated samples with H2SO4 have the same efficient in bleaching crude soybean oil with the standards and treated sample with HCl is more efficient in bleaching than the commercial products.

Jan 1, 2014

By R. Singh

The present paper deals with the development of flotation based process for enrichment of a lead-zinc sulphide ore from Ganesh-Himal region of Nepal. Detailed characterisation and flotation studies were carried out under varying process conditions. The sample assayed 2.47% Pb with 13.6% Zn. The ore was predominantly made up of spahlerite and pyrite in association with subordinate amounts of galena, minor amounts of pyrrhotite and chalcopyrite. Dolomite was the main gangue. The modal analysis showed the probability of fair liberation of sulphides from gangues around 210 microns but the locking of galena with sphalerite and other sulphides continued to finer sizes. Under the optimum process conditions the rougher lead and zinc recoveries were 96.3% and 90% respectively. Multistage cleanings of rougher products proved helpful in improving the concentrate grade, meeting the required specification. Based on the studies undertake a process flow-sheet for the concentration of the ore to individual lead and zinc concentrates was developed.

Jan 1, 2014

By M. Lak, M. Asghari, M. Saghaeian, R. Hejazi, A. Haratian

"Magnetic separation techniques are used extensively in mineral processing operations. Magnetic separators are robust and relatively easy to operate. As the ore get hard and low grade, fine grinding must be required mostly to allow for a high degree of mineral liberation. These processes encounter the magnetic separation process difficulty due to a significant change in the separation behavior of particles. This study investigates the effectiveness of a novel proven wet magnetic separator for the beneficiation of Lebedinsky (Russia) iron ore achieved through developing pole arrangement and tank design. Basis on the results of multiphasic simulation of a medium intensity magnetic separator (MIMS) and dense media tank using Magnetic Design Software, a new model of the MIMS separator was developed. The main of the new MIMS separator was focused on improving separation and the decreasing the number of separators in cobber stage of the plant. The new MIMS separator was tested into a pilot plant on the received samples from Lebedinsky iron ore plant. In addition to the basis on the results of the modeling, promising results of test work and previous experiences, it was claimed the unit capacity of new separator is 33.33% more than the existing separator that could decrease the number of separators. In addition, the significant energy saving in the same operational condition could be obtained without any important adverse effect on the final concentrate quality.INTRODUCTION Magnetic separation is a long-established method for the purification and removal of substances from fluids (Augusto et al., 1999; Buck et al., 2015; Hoffmann et al., 2002; Lauda et al., 2016; Lindner et al., 2010; Podoynitsyn et al., 2016; Rashidi et al., 2016), mainly in mining processing industries ranging from steel production to coal desulfurization as commercial technology (Andres, 1994; Augusto, 2002; Svoboda, 1987). High gradient magnetic separation as an effective method for recovering of weak and fine magnetic particles separation has undergone dramatic developments, and has also achieved extensive application during this time (Svoboda and Jujita, 1987). Magnetic separation operations can be categorized into high intensity as electrical (up to 20,000 gauss), Medium intensity (2000-5000 gauss) and low intensity (less than 2000 gauss) techniques. Magnetic separators offer a simple, clean and economic way to sort magnetizable ores and minerals. After pulverization, the material is run through an inhomogeneous magnetic field, where particles of different susceptibility experience different magnetic forces. The force increases with susceptibility, magnetic field and field gradient (Jongst et al., 1984).In magnetic separation, the difference in the susceptibilities of the various particulate materials is used to separate the material flow into two or more products (Wasmuth and Unkelbach, 1991). The magnetic force acting on a particle can be calculated using the following equation:"

Jan 1, 2018

Over the last four years, a major collaboration between CSIRO-MIS, UCT and JKMRC has produced two significant advances in the modelling of comminution. The Universal Comminution Model (UCM) uses parametric SPH/DEM studies of comminution and separation devices to calibrate mathematical models which are suitable for industrial use. The Virtual Comminution Machine (VCM) uses the same computationally intensive techniques based on discrete element modelling (DEM) and smoothed particle hydrodynamics (SPH) to directly model any comminution device by combining a CAD file describing the machine design, sophisticated ore characterisation methods and advanced particle scale flow and breakage simulation. The UCM should be useful for process analysis and optimisation of existing equipment and circuits while the VCM should make a major contribution to the evaluation and development of new machines. Progress to date is encouraging with several processes now well described using DEM. This paper also reports on progress towards combining DEM for particles with a realistic slurry model based on SPH for different types of comminution devices. In due course, this combination should allow accurate modelling of particle transport in wet mills to be combined with DEM models.

Jan 1, 2014

By J. Quinteros-Riquelme

Despite increasing demand, the supply of silver is limited by its inadequate recovery from ores. Due to its scarcity in nature, its high ore variability and complex mineralogy of current silver deposits, its recovery by mineral froth flotation presents a real challenge for process engineers. A silver ore often contains significant amounts of five to ten different silver minerals and knowledge of the mineralogy is a necessary precursor to flotation testing. In this work, a complex silver ore was treated by using batch laboratory flotation, in an effort to find the best experimental conditions to obtain the optimal silver recovery. Mineralogical characterization of feed samples was conducted using a combination of tools, namely the mineral liberation analyzer (MLA) and inductively-coupled plasma mass spectrometry (LA-ICP-MS), which indicated that most of the silver occurred as ?invisible? silver in pyrite. The pyrite assay of the ore was approximately 4%. The ore was processed in two flotation stages. The first stage, sulphide flotation, aimed to collect a sulphide mineral rich concentrate; then a non-sulphide flotation stage was performed by adding sodium sulphide and collectors to the remaining material in the cell, with the objective of obtaining a pyrite rich concentrate. To reach the target recovery of silver from this ore, various variables were altered. In the first stage: mixed collectors, activators, dispersants, and mainstream inert grinding were assessed. In the second stage, the conditions for sulphidization and subsequent flotation were both investigated. From the grade recovery curves for silver and sulphur it was possible to observe a similar metallurgical behavior for both elements, supporting the results given by the mineralogical characterization. Keywords: silver oxide, froth flotation, sulphidization, mig

Sep 1, 2012

By G. Zaitsev

In mining and mineral processing, ammonium and nitrate from residues of explosives and other sources are discharged to the aquatic environment. Nitrogenous compounds in mine water can adversely affect the aquatic environment. The aim of this work was to study the biological removal of nitrate from cold inorganic mine water at the pilot-scale in an operating underground mine. Seven-months pilot testing on biological removal of nitrate from inorganic mine water was successfully performed in denitrifying fixed-bed biofilm reactors. The feed to denitrification bioreactors contained 11 mg NO3--N/L. Methanol was added as an external carbon source to the denitrifying bio-reactor since the inorganic mine water contained only traces of organic compounds (<CODCr (50 mgO2/L). Nitrate removal reached 75 g NO3--N/m3/d with removal efficiencies above 95% at temperature below 4°C. Thus, removal of explosives-residues from cold inorganic mine water was shown in pilot-scale biofilm reactors.

Jan 1, 2014

By Yonghui Hu, Hongxiang Ran, Honggang Wei

"A new PVM vertical ring high-gradient high-intensity permanent magnetic separator authorized by China Invention Patent ZL201110294866.4, which featured with vertical magnetic field structure was developed to dramatically save energy consumption and running costs compared with electromagnetic separators. The specific magnetic circuit design ensures PVM separator generating high magnetic field intensity as well as solving equipment large-scaling. The newly developed industrial PVM separator has been proved suitable for recovery of weak magnetic minerals or purification of non-metallic minerals benefiting from its high background and induction magnetic field intensity up to 0.8/1.5T, stable service performance and low running costs. The first ?1.5mm PVM separator has been applied in removing iron from quartz sand in Fengyang, Anhui, and ?2mm PVM separator will be installed to separate hematite. Industrial applications and tests proved that PVM separators could gain similar separation effects and especially save more than 80% of power consumption compared with the conventional electromagnetic high-gradient high-intensity magnetic separator, which will contribute a lot for energy conservation and environmental protection. The development of high gradient magnetic separator technology has played an important role in utilizing weak magnetic minerals, which has been widely used in many mining enterprises. The main forms of high-gradient magnetic separators include both of electromagnetic high-gradient and permanent magnetic high-gradient. The vertical ring high-gradient high-intensity permanent magnetic separator features with high magnetic field gradient, large processing capacity and never clogging, which has been widely used in recovering fine weak magnetic mineral and purification of non-metallic minerals[1-3]. However, electromagnetic coils excitation needs more energy consumption, and relatively high running costs and maintenance costs as a result of the complicated cooling system. So permanent magnetization of the electromagnetic magnetic separation equipment is a very important research direction at present. With the continuous improvement of resource utilization standard and efficiency requirements, high energy consumption of the electromagnetic vertical ring magnetic separator have been highlighted, which has affected the economic benefits of mining enterprises to a certain extent. In the aspect of high-gradient high-intensity permanent magnetic separation equipment, considerable researches have been carried out at home and abroad and many small-sized prototypes were developed yet never strode into large-scale industry applications[4-6]."

Jan 1, 2018

By V. Sheikhzadeh, M. Saghaeian, R. Hejazi, A. Abazarpoor

"The morphology of pellet feed is known to influence several properties of iron ore pellets, including drop number, compression strength and reduction properties. The effect of grinding method on the particle size, specific surface area and particle shape of an iron ore concentrate has been studied. Grinding methods considered were ball mill and high pressure grinding rolls (HPGR). 5 different samples (Blaine= 1800, 1900, 2000, 2100 and 2200 cm2g-1) were used to compare the size, shape and specific surface of particles for each grinding methods. Particle size was meticulously examined by sieve analysis, laser sizing and image analysis. In samples ground by ball mill, it has been observed that the fraction of particles <10µm increases from 39% to 46% as the Blaine number increases from 1800 to 2200 cm2g-1. For HPGR samples, corresponding figures are 41% and 49% respectively. It is evident that for samples ground by HPGR, the fraction of fine particles is higher than that of those ground in the ball mill. To measure the specific surface area of particles, Blaine and BET were used. A higher real surface area was observed from HPGR treatment in comparison to ball mill grinding, provided by a higher porosity, cracks, roughness and new surfaces. Shape factor of particles was determined using three descriptors: circularity, roughness, and aspect ratio. It was also observed that particles produced by HPGR were more elongated, less circular, and rougher than those processed by the ball mill. 1. INTRODUCTION Particle size and shape are important parameters that can significantly affect mineral processing plants and pelletizing plant performances (Brozek and Surowiak, 2007). It has also been proposed that green pellet quality is directly related to the amount of fine particles in a pelletizing plant (Dwarapudi et al., 2008; Umadevi et al., 2008; Gul et al, 2014; Van der Meer, 2015). Particle size distribution and specific surface area (SSA) are also key factors that can control the quality of green and fired pellets. Processing circuits generally reduce the fines fraction to lower than the required specific surface area (SSA). It is therefore necessary to regrind concentrates to produce suitable pellet feed for further treatment in the balling and firing steps [1, 2]. Two main methods are used for re-grinding of concentrate; high pressure grinding rolls (HPGR) and ball mill. Given the different forces used to reduce size in these methods, it is expected the shape of particles will be different (Pourghahramani and Forssberg, 2005)."

Jan 1, 2018

By A. S. Choudhary

India is endowed with a reasonably large reserve of chrome ore, amounting to about 100 million tons in different grades and is one of the leading producers of ore/concentrate along with South Africa, Kazakhstan and others. Chromite production in India has registered a 10 times increase during the last 30 years. Till late 1940s, the practice was to mine the high-grade ore for making ferrochrome and charge chrome and export the same leaving the low and medium grade ores stacked around the mine as waste material. This practice was continued for quite some time till the increase in world wide de-mand of chromite initiated an increase in production of chromite ore in India and the aspects of ?economy of operation? and ?conservation of mineral? dawned on the producers and associated authorities. Recovery of chrome values from low and medium grade ore was initiated to produce high-grade saleable concentrate. Suitable legislation was made by Government of India to induce and provide incentives to the operators to do so. First large scale chromite beneficiation plant in India was commissioned about three decades back at Byrapore in the Southern state of Karnataka. The ore, rather simple in nature and relatively free from clay, was obtained from underground. The processing consequently was simple washing and wet tabling. Further more, some test work, on the samples from eastern coast particularly from Orissa, was carried out at an internationally reputed laboratory by a large private operator and the plant was set up. This consisted of a combination of crushing-grinding-de-sliming-classification followed by concentration in multi stage spiral concentrators and shaking table. The plant was commissioned and operated successfully. Soon a state owned company followed suit on the basis of test work carried out in a well equipped Indian laboratory. The plant worked satisfactorily after some initial teething trouble and the company plans to double the existing plant capacity by installing balancing facilities. This development prompted a number of operators, including industry leaders to join the fray and the chrome ore processing industry flourished in India. More and more operators are now in the process of adding capacities to their existing plants. This paper attempts to chart the evolution of chrome ore beneficiation industry in India through a case study with reference to an existing plant. The process technology adopted and modified to suit the altered requirements as well as the future trends are outlined.

Jan 1, 2014

By J. E. Gebhardt, D. McBride, T. N. Croft, M. Cross

"Heap leaching is well-established as a relatively low-cost and low-energy method of extracting metals from low grade ores. However, the design methodology, attention to the engineering details during heap construction and the long time scale in metal recovery makes the process susceptible to significant variation in the success of a heap leach operation. Often the laboratory predicted recovery rates are not achieved on site due to poor understanding of the complex physics of flow and coupled solid-liquid-thermal reactions within the multi-dimensional heterogeneous ore body. Given the large scale of commercial operations, small changes in metal recovery can substantially change the operating profitability. While there are a variety of approaches to heap leach modeling, computational fluid dynamics (CFD) modeling coupled with leach kinetic models offers a methodology to describe and understand the complexities of heap leaching. The CFD model uses leach kinetics specific for the mineralogy of the ore, including gangue chemistry, and provides an energy balance to calculate and predict temperature. Coupled with the CFD model’s inherent capability for modeling complex fluid flow, the physics and the chemistry of the heap can be simulated. This provides a tool for engineering design, as well as forecasting heap production under different scenarios. The calibrated model is used to simulate a three-dimensional test heap under fluctuating meteorological data, such as precipitation events, periodic solution application, and notably temperature. These simulations provide support for a methodology to design and engineer heap leaching of low grade copper sulfide ore. INTRODUCTION Worldwide copper ore reserves are faced with decreasing head grades with copper sulfides, particularly chalcopyrite being the predominant mineralogy (Nesse, 2000). Heap leaching offers an economical way to recover copper from low grade ore. The ore is stacked and a leach solution is applied and allowed to trickle though the porous bed of ore to extract target metals. The heap can be built with run of mine material or crushed ore and is constructed in order to achieve percolation of the leach solution to all regions. Bartlett (1998) provides an authoritative overview of the solution mining process where the leach solution interacts with the solid, the lixiviant dissolves the target minerals from the solid into the solution, and the dissolved species are transported out of the heap for subsequent recovery. Petersen (2016) provides a recent review of heap leach technology and emerging and potential future applications, and Ghorbani et al. (2016) summarizes the current state and challenges of the technology. Early applications of heap leaching offered a low cost technique to achieve high recoveries from oxide ores, typically greater than 70% depending upon the kinetics of reaction. As world copper resources transition to mainly copper sulfide mineralogy, such as chalcopyrite based ores, achieving high recovery from these copper sulfide deposits is proving more difficult due to the complexity of the leach kinetics, which leads to low leaching efficiency."

Jan 1, 2018

By F. L. Wang

The purification process of water-mining carnallite and rough potassium chloride concentrate from Qinghai Salt Lake Industry Group Co. Ltd. are investigated by the preprocessing-reverse flotation technology respectively. The results show that the impurities such as calcium sulfate and sodium chloride can be effectively removed from water-mining carnallite ore and rough potassium chloride concentrate by the new technology, the low-sodium carnallite is obtained and the final potassium chloride product greatly upgraded. The content and the recovery of KCl in the low-sodium carnallite are 25.78% and 97.50%, meanwhile the content of NaCl, CaSO4 in the low-sodium carnallite are 0.56% and 0.24%, and the removal of sodium chloride and calcium sulfate in the low-sodium carnallite are 97.48%, 85.10% respectively. The KCl content and recovery of high quality potassium chloride product are 98.25%, 96.70%, and CaSO4 content is 0.40% with 83.24% calcium sulfate removed in the high quality potassium chloride product.

Jan 1, 2014

By Paul Gottlieb

This paper reviews the status of automated applied mineralogy today and describes the history and fundamental theoretical and practical bases underpinning the development of automated systems. Details are given of the technical challenges that were faced in creating the new technology and in applying it to a range of applications. In recent years, automated mineralogy has become established as an essential enabling technology for the reliable acquisition of statistically sound comprehensive mineralogical and metallurgical data. This has had a revolutionary effect on the industrial use of such data in the study of geology, mining and mineral processing. Previously, using manual methods, it was not feasible to attempt this work because the large data sets required could not be assembled in a realistic timescale. There was a reliance on individual expert mineralogists and this was not scalable. The speed, reliability, detail and repeatability of the modern automated measurements has now made this type of analysis routine. Automated Applied Mineralogy has come of age! More than 100 systems have been installed around the World. Automated mineralogical analysers such as QEMSCAN® were originally developed as diagnostic metallurgical tools to improve mineral processing plants using samples drawn from plant surveys, bench and pilot-scale tests. They were used mainly for the assessment and auditing of size fractions of mill products, such as concentrates and tails. Subsequently, they began to be used for concentrator design and optimisation where ore characterisation was used to help understand the relationship between the feed ore and its subsequent behaviour in the plant. They are now widely used to measure exploration cores and drill chips from drilling programs to predict eventual metallurgical performance. Ore samples can be classified into metallurgical, as well as geological types, by combining mineralogical features in the ores with metallurgical properties related to grade control, separation, comminution, flotation and leaching behaviour. Three-dimensional block models of ore deposits are now being created based on processing response in addition to geological and mining properties. The development of automated systems began in Australia, the United Kingdom and Canada in the late 1970s and early 1980s. There were many technical challenges. Mathematical theories of randomness, sampling theory, image analysis and stereology were developed to ensure sample representivity so that meaningful information could be obtained. Sample preparation, presentation and measurement methods were developed to ensure that the random sampling was preserved during the measurements. Methods of automatic measurement and mineral identification evolved from the use of electron microscopes, fitted with backscattered electron brightness and energy dispersive X-ray detectors. Operational procedures were required to ensure that these instruments could accommodate a large number of samples and operate unattended for long periods of time. The new technology was progressively applied to a range of commodities and applications and new analysis methods, such as liberation measurement, were needed for metallurgical interpretation of mineralogical data.

Jan 1, 2014

By T. V. Vijaya Kumar

Most of the iron ore washing plants set up in India consist of sizing of the ore by dry / wet screening, washing and classification by screw classifiers followed by multi-stage hydrocycloning of screw classifiers? overflow. The underflow of the hydrocyclones forms the concentrate which is used for pellets making. As the cut-point of hydrocyclones is generally at 20 microns, relatively lower diameter cyclones in a cluster with parallel feeding are used. This is found to, often, result in choking of the spigots, at times, by extraneous material as well reporting along with the slurry. It is observed to lead to sub-optimum performance of the cyclones with loss of iron values into cyclone overflow and thereafter into tailings. Analysis of data of an operating beneficiation plant (Beneficiation Plant - 1, BP - 1) of M/s Jindal South West (JSW) Steel Limited, Karnataka, India over a period of one year indicated that weight recovery of the concentrate from two-stage hydrocycloning was 45% (with respect to feed to the cyclones) and assaying 63.43% Fe, 4.43% SiO2 and 2.32% Al2O3. CSIR - National Metallurgical Laboratory - Madras Centre (NML - MC), India developed flotation process for processing screw classifier overflow with a view to improve the recovery of ultrafine iron values from it. Detailed investigations at laboratory scale flotation column and on-site pilot plant trials proved that the production of the concentrate and productivity of the plant could be enhanced by adopting reverse cationic column flotation technology. It was established that a typical screw classifier overflow analyzing 60.54% Fe, 5.95% SiO2 and 3.67% Al2O3 could be upgraded to 64.21% Fe, 2.64% SiO2 and 2.20% Al2O3 with 82.7% weight and 84.7% Fe recovery. This translates into an increase of 80% in weight recovery of the concentrate compared to what is being obtained, at present, by two-stage cycloning. It had an added advantage of reduced SiO2 in the concentrate. Thus, SiO2 in the final concentrate could be reduced to 2.64% from 4.43% by adopting column flotation. The concentrate so generated meets the stringent specifications, especially in terms of alumina in it(should be less than 2.50%) for pellets making. Later, JSW Steel Limited set up the flotation plant in BP - 1 based on the process developed by NML - MC and was commissioned in 2010. Keywords: iron ore, washing, ultra fines, alumina reduction, column flotation

Sep 1, 2012

Copper nickel separation is performed by mineral processing techniques both pre and post smelting in Copper Cliff at Vale Canada?s Operations. The separation at Clarabelle Mill takes advantage of the ore mineralogy to affect a separation on the rougher concentrate where chalcopyrite and pentlandite exhibit high liberation and high recoveries thus their separation is simple although incomplete. The copper concentrate comprises only 50% of the copper in ore with the remaining copper being separated post smelting in the Matte Separation plant where the slow cooled Bessemer Matte is again treated by mineral processing operations using flotation to separate the chalcocite and heazlewoodite and magnetic separators to remove a metallic nickel alloy. This paper discusses the mineralogy, separation processes and work currently underway to improve the separation of copper from nickel in these plants.

Sep 1, 2012

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 M. K. G. Vermaak

Kimberlite weathering has been a topic of ongoing research within De Beers for many years. Using kimberlite weathering as an alternative to crushing has many advantages e.g. power and reducing diamond breakage. Weathering could also possibly be used in conjunction with crushing just to weaken the material and reduce power consumption. These forces have driven current research to investigate whether kimberlite weathering could be utilised for these reasons. Weathering in this context does not refer to weathering over long period of time but rather to disintegration of the material in aqeous media in relative short time periods. Previous published work discussed that the presence of smectite renders kimberlite weatherable and that the amount of smectite determines the rate of weathering (Morkel and Vermaak, 2006). The current work investigates whether cation ex-change or the adsorption of organic species in the smectite interlayer could influence the observed weathering behaviour. The results show that cation exchange does take place in the presence of cation species and that the weathering behaviour can be drastically improved with especially Cu2+ cations. Concentration and time effects of the weathering was also investigated. Weathering tests with organic species such as ethanol, methanol, edta, pentanol, butanol, acetic acid and oxalic acid was performed. The results show that organic species does improve weathering but under these testing conditions was not as effective as cations.

Jan 1, 2014

The present study is devoted to improvement of the leaching efficiency during phosphorous removal from high phosphorous gravity-magnetic concentrate. Before leaching the concentrate has been subjected to roasting with the addition of either Ca(OH)2 or CaO. The oolitic iron ore is roasted at 900°C for one hour. This reflects in reaction between alkaline earth additive and quartz, aluminosilicates, phosphorus, and some other minor components of the gangue minerals. The application of leaching, physical separation, and wash out of salts has resulted in the decrease of phosphorus from 0.7 to 0.15 % and it is established that the major influencing factor is the concentration of acid and to a less extent duration of the leaching process. About two third of the phosphorus can be removed by roasting with 3 % CaO to hematite, coarse grinding to d50 0.3 mm, dry high intensity magnetic separation and leaching of the magnetic fraction with hydro-chloric or nitric acid.

Sep 1, 2012