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By G. C. He

Effects of irregularity, rough surface and aggregation of fine particles on ultrasonic attenuation are significant. The effects should be considered while predicting particle size by ultrasonic attenuation technology. The scanning electron microscope micrographs analysis also shows that particles surface is rough and irregularity. Any slurries has its fractal structure and its special fractal scale and dimension, so, effects of irregularity, rough surface and aggregation of fine particles can be de-scribed by fractal model. The discrepancies between predictions of ultrasonic attenuation based on the assumption of smooth spherical particles and data obtained from slurries of irregular particles indicated that there were different fractal structures. The ultrasonic attenuation model was modified by fractal dimensions. The result of experimental data and analogue calculation indicated that pre-dictions of the fractal modification of ultrasonic attenuation model show good agreement with experimental data. On the other hand, from the values of fractal obtained by inversely calculation, the degree of effects of irregularity, rough surface and aggregation of particles can be estimated. The positive value of fractal dimension indicates that the aggregation has the dominant effect on ultra-sonic attenuation, otherwise, the irregularity and rough surface has the dominant effect.

Jan 1, 2014

By Claudio L. Schneider, Peter R. King, Reiner Neumann

"Predicting the liberation spectra that are produced from breakage of two-phase ores under the random fracture assumption can be accomplished by measuring the conditional, on length, linear grade distribution directly from images obtained from a representative sample of the unbroken texture. The technique tremendously simplifies the prediction problem by avoiding the multiple convolutions that arise from the traditional method based on a description of texture from a measurement of the chord length distributions associated with each phase in the unbroken texture. For a 3-phase system, the phase transition probabilities associated with the textural information make the traditional calculation an almost insurmountable mathematical problem. The direct measurement procedure on the other hand can be expanded to three phases comparatively easily.A coal sample is used here to demonstrate the procedure. It is concluded that the conditional, on length, linear grade distribution can be predicted in the same fashion for multi-phase systems. Accurate stereological conversion is the practical hurdle to be overcome for multi-phase systems, but it is already a reality for 3- phase systems."

Jan 1, 2003

New technology for on-line particle size analysis of mineral slurries has opened up new applications for particle size measurement. In some cases the particle size distribution of the final concentrate is an important quality issue. This paper discusses established on-line particle size analysis technologies and presents experiences on the use of a new technique employing laser diffraction in several minerals processing operations. The main innovations in the new instrument are a simple dilution system and multiple scattering correction algorithm, which allows wide solids content variations of diluted sample in the measurement cell. Representative sample for laser measurement is produced by a simple and reliable dilution system. The applications discussed are; Blaine number measurement of Fe concentrate before pelletizing, grinding of variable batches of ore and paste thickener control.

Jan 1, 2014

By O. A. Bascur

"In recent years, metal producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Internet of Things (IoT) is one of many transformational initiatives, which can fundamentally revolutionize how industrial complexes operate. Whatever the issue, the answer is in the abundant and growing quantity of real time data and events collected in the grinding and flotation circuits in a mineral processing plant. Based on earlier work, today a grade recovery model permits identifying the best operating conditions in real time. We will review the strategy for increasing the value of the abundance instrumentation in current plants. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut to reduce metal losses in the flotation circuits. The large amount of sensors in a flotation circuits permits to estimate the recovery and to find the optimal froth depth and aeration using an air holdup flotation model. The paper will describe the strategy of classifying data for on line generation of insights to using operational intelligence tools. We will discuss the implementation Recovery/Grind strategy with industrial examples in non-ferrous mineral processing and iron beneficiation.INTRODUCTIONThe declining supplies of high grade ores and increasing consumption of mineral and metal products have demanded higher operational efficiencies with minimum capital investments. The objective of copper flotation objectives are based on maximizing the dollars return on the concentrate produced. The economic efficiency is maximized by manipulating the circuit along the grade/recovery curve relationship. To achieve such objective improved stabilization of the grinding and flotation circuits are required (Oosthuizen, Craig, and Jamsa-Jounela, 2017)."

Jan 1, 2018

By Janne Kytökari

Controlling a wide range of minerals processes with single control system is an ordinary way to operate in mines all over the world these days. However the potential of these systems is not yet fully recognized nor utilized. The key issue is to manage the information in a way that enables automating the day-to-day tasks, quality control and safety functions. At the same time it provides means for optimization and constant improvement of processes creating a working environment where the system helps employees to do their key tasks instead of searching, modifying, and transmitting the huge number of information arising every day. The distribution of control system nodes enables the other processes to run heedless of a problem occurring in one of the sub-processes. Also the control room can be in remote location such as in large city removing the need to travel substantially long distances to plant sites every day. When all essential information is brought to the same place there is less risk for a mishap to happen due to information breaks that are often the cause of them. One of the biggest single reasons that result in production losses are break downs of machinery usually caused by normal wear, misuse, incorrect utilization rate etc. For this reason it is important to measure the condition of machines using vibration measurement and diagnostics. By moving from failure or time-based maintenance towards predictive or performance maintenance generates eventually a steady and predictable process but also results in significant long term savings. The mineral process at Talvivaara mine is based on bioheapleaching, whereby metals are leached from ore as a result of bacterial action. Bioleaching is a fairly new technology used in metals recovery. Therefore it is important for the mine to collect and analyze data from different stages of the minerals process. Talvivaara mine?s Metso DNA system has integrated machine condition monitoring and information management. These are not only necessary but also crucial in environmental conditions where the outside temperature can drop below -35°C, where ice and snow dominate the landscape and impact the equipment for four months a year and where distances between equipment can be up to 7.5 kilometers. Keywords: DCS, analyzer, machine condition monitoring, automation, remote communications, optimization, mining, metso DNA, Talvivaara

Sep 1, 2012

By Ana C. C. Pacheco, Maurício L. Torem

"The aim of this work was the study of the effect of the type (Fe3+, Al3+ and Fe3+ and Al3+ mixture) and of the coprecipitant concentration on As5+ removal by ACF. Removal of As5+ using Sodium Dodecylsulfate (SDS) as a collector was studied by Adsorbing Colloid Flotation (ACF) at laboratory scale. The morphology of the precipitate retained in the foam was analyzed by Scanning Electron Microscopy (SEM/EDS).By comparing the coprecipitant type and concentration studies it could be concluded that As5+ removal in the presence of Fe3+ (160 mg.L-1) alone, or a Fe3+ (80 mg.L-1) and Al3+ (40 mg.L-1) mixture, is equivalently effective (99,9%) and greater than in the presence of Al3+ (80 mg.L-1) alone (97,7%).Through SEM/EDS analyses, it was possible to observe that both morphology and composition of the precipitate produced in the solution and retained in the foam depend on the physico-chemical conditions of the system, that is, on the species present in the solution."

Jan 1, 2003

By J. J. Cai

The status of fossil fuel and secondary resource in metallurgy industry in China were reviewed, and conversion efficiency of fossil fuel, utilization technologies of secondary energy were studied. Fossil fuel, accounting for over 90% of energy structure in metallurgy industry, took in the highest flight in China, and a great deal of which was converted to secondary energy through the equipment of blast furnace and coke oven. These secondary energy which were mostly made of blast furnace gas(BFG), coke oven gas(COG) and Lindz Donawitz gas(LDG) occupied about 30% of total secondary energy. The way enhancing fossil fuel conversion efficiency, secondary resource recovery and the secondary energy such as BFG, COG, LDG utilization promoted to save fossil fuel was discussed in this paper. And efficient use of lower caloric value fuel was studied, such as preheating combustion air and fuel, generating electricity power etc. and regeneration purposes of high-caloric fuel was also researched, for producing hydrogen, methanol or direct reduction iron etc. The using model of secondary energy at iron and steel works was presented as fuel and chemical materials. The results suggest that utilization of these energy efficiently and reasonably could help to energy saving and environment protecting.

Jan 1, 2014

By Georges Delemontex, Nigel Grigg

"Pre-concentration of precious metal and base metal ore types is becoming more relevant with the discovery, development and operation of many lower grade deposits around the world. The fluctuations in metal prices and currencies expose many mines to risks especially dealing with low and variable ore grades. Pre-concentration, the process of concentrating the valuable metal into a smaller mass yield, effectively results in the introduction of higher feed grades to milling circuits. Gangue rejection, the removal of lower S.G. waste rock from the circuit, not only results in higher downstream grades but also potentially removes harder, non-valuable mineral, providing significant power savings within the circuit. The pre-concentration or ‘gangue rejection’ process offers a number of benefits when considering the treatment of marginal ore deposits, especially if it can be performed at a coarse crush size; these benefits include a reduction of the operating costs and the feed of more metal units to the mill. Gekko Systems has effectively utilized the Inline Pressure Jig (IPJ) to pre-concentrate the valuable metal, achieving high primary recoveries into a range of mass yields resulting in upgrade ratios between 2 and 10 times. This paper explores: the benefits of pre-concentrating ‘marginal’ ore deposits prior to the milling circuit; the selective rejection of ore types that may affect either the recovery or comminution process; and also looks into the potential to effectively reduce the ‘cut-off’ grade when considering the mine planning process. Case studies of projects using the IPJ to pre-concentrate and reject gangue are also included. Pre-concentration and gangue rejection provide the potential to develop marginal ore deposits, thus providing higher grades, less gangue and more metal at a lower operating cost to producers."

Jan 1, 2014

By E. Isokangas

The production of minerals for economic use is a two-stage process, involving mining to extract the mineral from the ground, and processing to convert the mineral into a marketable product. Generally, mining and processing have been viewed as self-contained entities. Both have separate objectives, separate cost centres and key performance indicators (KPIs) that do not reflect the customer/supplier relationships that inherently exist. However, mining and processing operations are inter-connected and therefore intimately inter-related with the performance of one operation affecting the performance of another. Optimizing each stage separately without considering the whole system often misses potential economic benefits and energy savings. During the past fifteen years, the authors have been involved in implementing a holistic methodology ?Mine to Mill Process Integration and Optimisation (Mine to Mill PIO)? to maximize the overall profitability of the operation rather than just optimizing any individual process in a mining operation. Metso Process Technology and Innovation (PTI), along with their project partners, have conducted several projects to significantly increase their production- generating typically 5% to 20% higher throughput and improve the overall mine and concentrator performance through PIO methodology. This proven methodology has applications ranging from greenfield projects to long-standing operations with AG/SAG, HPGR or conventional grinding circuits. This paper explains the Mine to Mill PIO methodology and discusses the benefits of such an approach on the energy consumption, the overall costs and benefits of mining operations. The paper also summarizes several case studies illustrating the use of PTI methodology in a variety of applications. Keywords: integration, optimization, simulation, modeling, mine-to-mill, comminution, blast, drill, crushing, grinding

Sep 1, 2012

By Harri J. Lehto, Marja I. Oja

Empirical models used for predicting the performance of screens on the basis of capacity, cut size, water split and grade efficiency curves were evaluated. This paper reports experimental results obtained with single-deck Derrick screens. The performance of the screen was tested with limestone in a separate screen set-up, in a pilot plant and in industrial scale test runs. The results of pilot plant experiments showed that the measured water split was higher than the measured bypass. This is an indication to that water flow does not entrain the same proportion of all fine particles present in the feed which is advantageous for screening. The experimental design for the industrial test runs was made on the basis of the pilot plant tests. Suitability of the existing models has been checked and accuracy compared. The tests showed that best grade efficiency model was the Rosin-Rammler model. An empirical model for the evaluation of the model parameters as a function of pulp density of the feed and the load of the screen is suggested.

Jan 1, 2003

By N. D. Ilankoon

"The use of thiosulfate as an alternative lixiviant for cyanide to treat complex refractory ores followed by the use of ion exchange resins (IX resins) for gold recovery has become an industrial reality. In this study, polyethylenimine (PEI) coated iron oxide magnetic nanoparticles (MNPs) were used to recover gold from the leaching solutions that consist of calcium thiosulfate, copper and gold. The gold loaded MNPs were easily separated from the solution using an external magnetic field. Proposing a novel adsorbent with characteristically easy solid-liquid separation, to recover gold from synthetic thiosulfate leaching solutions and gold elution and reuse of MNPs were the main objectives of this study. Adsorption isotherm studies revealed that the data fitted both Langmuir and Freundlich isotherm models equally well. The maximum adsorption capacity was 18.5 mg/g at pH 8 and 50?C. According to thermodynamic studies the physisorption process was exothermic and spontaneous. Gold and copper elution, and the regeneration and reuse of the nanoparticles were investigated and promising results were obtained. Different elution systems comprising sulfites, chlorides, glycine, EDTA (ethylenediaminetetraacetic acid) and sodium hydroxide were considered. Among them, EDTA for copper elution and NaOH for gold elution were the most efficient eluants. Regeneration and reuse studies revealed that the MNPs can be used for several cycles without significant performance loss. INTRODUCTION Although cyanidation has been used for gold leaching for more than 100 years, some major drawbacks associated with cyanidation have led to a quest for alternative lixiviants for gold leaching. Cyanide is ineffective in treating carbonaceous refractory ores as gold cyanide complex is adsorbed onto the native carbon in the ore itself known as preg-robbing. On the other hand environmental concerns associated with cyanidation drives the need for environmental friendly alternatives for cyanide. As of today, thiosulfate is known to be the most extensively studied and most promising alternative lixiviant for cyanide in both technical and environmental perspectives (Aylmore and Muir 2001, Oraby 2009)."

Jan 1, 2018

By Jing Zhou

2-hydroxy-3-naphthoy hydroxamic acid code name F203 is a good collector of cassiterite, 1-hydroxy-2-naphthoy hydroxamic acid code name ZJ-3. F203 and ZJ-3 are similar series of isomers. They have similar naphthye, and similar series of functional OH and ?CONHOH, but the seat of OH and ?CONHOH group are different, on the F203 is 2.3; on the ZJ-3 is 1.2, ortho position too. According to Isomeric principle ZJ-3 is a good collector of cassiterite slime too. Using ZJ-3 as collector flotation -10µm occupies 90%, grade 1.16% Sn cassiterite slime of Da Chang Chehe concentration plant, pass one coursing flotation, two cleaning and one scarenging flotation, and obtains grand 18.26% Sn, recovery 92.68% cassiterite concentrate. The result proves the Isomeric principle of flotation reagents is correct again. This principle may supply to synthetize new flotation reagents reference. Keywords: F2O3, ZJ-3, cassiterite flotation, Isomeric principle, Isomeric principle of flotation reagents

Sep 1, 2012

By Heikki Häkkänen, Tommi Kauppinen, Navid Khajehzadeh

"There are a variety of methods suitable to analyse elemental and mineralogical contents of rock drill core samples. Current demands are on fast exploration and objective analysis of ore samples. This paper proposes a combination of Laser-Induced Fluorescence (LIF) and image processing, entitled LIF-imaging, as a potential method for automated mineral analysis of the drill core samples. It is shown that LIF-imaging can produce a mineral map of the fluorescent minerals existing on the surface of the drill core samples. The test cases are drill core samples from a Ni-Cu mine situated in Kevitsa, Finland. The main prerequisite of LIF-imaging technique is a reference data, linking colours to the minerals. This study describes the calibration of LIF-imaging technique using precise but slow Raman spectroscopy. Using regularized logistic regression, a model is obtained that classifies the minerals based on their emitted fluorescent colours in the digital images. The abundance of each mineral group is estimated by pixel counting. The results are compared with X-Ray Diffraction laboratory assays performed on the same samples. The results show that the interpretation of the fluorescent minerals through LIF images corresponds to the XRD results. Furthermore, the utilization of the logistic regression to interpret the existing fluorescent minerals greatly improves the technique."

Jan 1, 2014

Much has been published in recent years on the challenges facing the engineer of the 21st century and the consequent challenges facing the education providers and industry. The world is changing rapidly on the social, economic, political, technical and environmental fronts and our metallurgists/mineral processing engineers of the future will arguably need to have a different set of skills than those which were traditionally regarded as adequate during the latter half of the 20th century. This paper attempts to explore some of these issues and their ramifications.

Jan 1, 2014

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 Z. H. Li

In connection with the features of characteristic waste water (containing cyanogen, arsenic and heavy metal) pollutants discharged by gold industry as well as the environmental features at the location of gold production enterprises, this paper briefly described the traditional method of treatment, and focused on the argument for technologies of clean production, advanced treatment and process control technology. Moreover, it clarified the future policies and development trend for treatment on characteristic waste water from gold industry.

Jan 1, 2014

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 Junji Shibata

In a present process to treat the tungsten carbide tool waste, the wastes are roasted in air and then an alkali leaching is carried out in an autoclave. An environmentally friendly process is required to recover rare metals (Co and W) from the wastes. The effect of mechano-chemical (MC) treatment on leaching of rare metals was investigated in this study. The solvent extraction and crystallization-stripping methods were applied to separate and recover tungsten and cobalt in the leached solutions. The MC treatment for the rare metal leaching is effective to dissolve rare metals from the wastes due to the change in crystalline structure of WC and oxidation of WC with KMnO4. Cobalt ions are extracted with D2EHPA by a cation exchange reaction. Tungsten in the leachate can be extracted by TOA (tri-octyl amine) as an extractant, because tungsten species exist as a form of anionic species in acidic solution. The rare metals in organic phase are recovered as insoluble salts such as oxalates and ammonium salts in the crystallization-stripping process. Keywords:unheated oxidation, solvent extraction, crystallization-stripping, recycling

Sep 1, 2012

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 Jury P. Nazarov

"At present the traditional study of crystal lattices of nmerials in a topic “flota tion mineralogy ” is used up. The present investigation is development of the a sclsical approaches to t he analy sis of ideal crystal lattices and f ormation on the basic obtained results of consultation, having practical chara cter.The strategy of develop ment floatation reagents i s offered, which basic pr inciple – complementary assembling m olecules forming surface co mpounds so thatth e steric charact eristic of the “visitor "" (of a polar gro up of molecule SAS) corresponded to the st er ic requirements of the ""o wner"" (elementary cell of a mineral), or coincided inter molecular cavities). In itsh case process of for mation of surface com pounds ca n be considered(a first approximation) as a realization of a principle of the design er "" LEGO "".The approach, which basic idea consi deration actioonf reactant ions and ions of ele mentary cell as three-di mensional objects is developed. And at suchp paroach the laws of a ster eometry - laws describin g spatial effect s are applicable. Thus it is possible toconsider a miner al surface as a mat r ix - basis for formation of the requirem ents to polar group of a molleec cuollector, and or (it is possible) depressant. As a whole approach represents a generalized principle double com plementation, enveloping both power, and geometric asp ects (concept ""lock "" and “key "" - spatial conform ity. Figure 7 (left). Fragment of a crystal lat tice of ap atite. Oleic acid ions interact on ly with th e calcium cations locate d on a long axi s of an elementary c ell. Magenta colour represe nts the calciu m cations, which are n ot particip atin g in interactio n, as th e degree of screening by ions neighbours exceeds 1.Figure 2. (right)The illustration of space complementary. “Afterbuilding” an elementary cell of apatite (radical PO4) related molecules of the visitor – alkyl phosphate (polar group PO4). Cations of calcium are not shown."

Jan 1, 2003