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By Reinol Compañero, Ivy Gonzales, Herman Mendoza, Brian Buenaventura

"The extraction of gold in the Philippines has been a significant challenge for the past decades. Around 70-75% of gold mined in the country can be accounted from the small-scale mining industry which primarily use the traditional cyanidation and amalgamation; processes which have been advocated due to its adverse affects to health and environment. To address this challenge, an alternative clean and sustainable technology was developed for the small-scale miners to recover gold and other metal/mineral values efficiently from Philippine ores. An initial survey was conducted and followed through with extensive mineralogical investigations ascertain the best method applicable. It was determined that Philippine gold occur in ore as (1) very fine particles in the microns range, (2) free-milling, which is in abundance, and (3) locked particles with sulfides --- it was concluded that enhanced gravity concentration and flotation are viable alternatives. A comprehensive test regime was followed to check the response of the ores obtained from different small-scale mining districts across the country. It was shown conclusively that the gold ores respond positively, with recoveries using gravity concentration and flotation of at least 95% and 88%, respectively; exceeding the nominal recoveries using cyanidation or amalgamation. A specific process flow was designed for each type of ore with customized parameters. It was determined that while capital expenditure of implementing these alternative processes is higher than what is currently being used, the operational aspects show that it is much more economical to apply enhanced gravity and flotation. It should be noted that the process developed addresses the critical issue of environmental costs which should be more than enough to justify the shift from the current to the novel and sustainable technologies."

Jan 1, 2014

By E. V. Zelinskaya

"Mineral and industrial raw material mining and preparation make a negative impact on the environment. The main types of impact are the land resources gathering, soil and water balance disturbance, surface-water, underground space and atmospheric air pollution, as well as the vast amount of solid and liquid waste production. Considerable attention in recent decades has been given to waste recycling. The task is to maximize the use of both newly formed and accumulated solid and liquid wastes. The mining and mining and smelting enterprises industrial waters are a very promising source of secondary hydromineralic raw materials. They have high concentrations of not only calcium, sodium, but also, for example, lithium, rubidium, heavy non-ferrous metals. In general, unfortunately, we have to state that today there is no wide practice of extracting valuable components from waste enrichment, as well as processing of man-made waters to extract metals from them. The quantity of extracted components from underground, and furthermore passing waters, is insignificant. At the same time there is a tendency to increased demand for rare metals: Sr, B, Br, I. This is explained by their wide use in many industries. For example, the consumption of lithium products is steadily increasing. The obtained results showed that in the liquid phase in connection with high salt content and a significant difference in the macro- and microcomponents contents, conditions are initially created for the microcomponents selective isolation possibility. The identified conditions realization is most possible in such technological processes as cryotechnology, sorption and ion flotation. There is an urgent need to expand research in this direction and to recognize as a publicly important task the mining and industrial waste processing full-scale introduction into the practice of operating mining and processing enterprises and iron and steel companies.INTRODUCTION Mineral and industrial raw material mining and preparation make a negative impact on the environment. The main types of impact are the land resources gathering, soil and water balance disturbance, surface-water, underground space and atmospheric air pollution, as well as the vast amount of solid and liquid waste production."

Jan 1, 2018

By G. V. S. Murthy

Beach Placer Ilmenite is an important source for production of titanium metal, titania slag and pigment grade titanium dioxide. Besides, these well known applications for which Ilmenite is mined and processed, there are other emerging processes that are being tried for obtaining highvalue products. Synthesis of Ilmenite based materials for varistor applications and direct electrochemical reduction of Ilmenite to produce ferrotitanium are two such attempts being discussed in this work. In this paper, recent efforts undertaken to study the electrical and magnetic characteristics are discussed. Ilmenite, FeTiO3, is one of the mixed-valence transition metalbearing minerals, inwhich Fe can be in two different oxidation states, Fe2+ and Fe3+.. Similarly, Ti can be in Ti3+ and Ti4+.Ilmenite is inherently suitable for making Varistors, which are devices, used for limiting the transient voltage surges in a circuit. Varistors produced from Ilmenite can withstand harsh environments seen in nuclear reactors and outerspace. Electrochemical reduction of Ilmenite can be used to prepare ferrotitanium directly without any reductant. The process essentially involves removal of oxygen from the mineral through electrolytic action using calcium chloride as electrolyte and graphite as anode. At a temperature of 950°C, it is shown to be possible that all the oxygen can be removed from the Ilmenite sample, which passes through the electrolyte, to form CO/CO2 at the anode. The process has immense potential for cost effective production of titanium metal as well. Results of the above developmental works are presented in this paper. Keywords: beach placer ileminite, varistor applications

Sep 1, 2012

By T. Lang

Clay sorbents from the North Bohemian Brown Coal Basin represent important but still some-what neglected accessory raw material. Submitted paper is concerned with relation between mineral structure, sorptive efficiency and reclamation exploitation of these rocks. Characters and localities of main clay sorbents from the North Bohemian Brown Coal Basin are shortly evaluated in an introduction. In next part, methodology of mineralogy survey for these accessory raw materials is stated, it is based on diffract analyse with D 5000 Siemens X-ray diffracto-meter. At the conclusion results are stated of mineralogy analyses from several clay sorbents. The determination of the zeolite and montmorillonite localities was accentuated. The paper presents also possibilities of practical clay sorbents utilization, especially by reclamation works.

Jan 1, 2014

By C. R. Mambote

One of the processes developed for vanadium recovery from the fly ash of crude oil is through acid leaching. In the process, iron is one of the impurities that should be removed before vanadium precipitation, due to the fact that iron tends to co-precipitate with vanadium. The mechanism of iron precipitation is understood in terms of ferric hydrolysis, followed by the dimerization and subsequent polymerization of the crystalline iron compound. In order to develop a new approach for the fly ash processing, in the present paper the precipitation of iron from the liquor after the leaching process was studied with addition of NaOH or NH4OH in the presence of H2O2 or Na2C2O4 at 80°C. The objective was to investigate the feasibility of the selective precipitation which could be applied to vanadium and nickel recovery from the fly ash. The experimental results show the difficulties of removing iron by precipitation without co-precipitating nickel and vanadium.

Jan 1, 2014

By M. Evertsson, K. Bhadani, E. Hulthén, M. Bengtsson

"Modelling and simulations for mineral processing plants have been successful in replicating and predicting predefined scenarios of an operating plant. However, there is a need to explore and increase the potential of such simulations to make them attractive for users. One of the tools to increase the attractiveness of the simulations is through applying optimization schemes. Optimization schemes, applied on mineral processing simulations, can identify non-intuitive solutions for a given problem. The problem definition itself is subjective in nature and is dependent on the purpose of the operating plant. The scope of this paper is to demonstrate two optimization schemes: Multi-Objective Optimization (MOO) using a Genetic Algorithm (GA) and Multi-Disciplinary Optimization (MDO) using an Individual Discipline Feasible (IDF) approach. A two stage coarse comminution plant is used as a case plant to demonstrate the applicability of the two optimization schemes. The two schemes are compared based on the problem formulations, types of result and computation time. Results show that the two optimization schemes are suitable in generating solutions to a defined problem and both schemes can be used together to produce complementary results. INTRODUCTION The comminution process for a mineral processing plant consists of multiple crushing and classification stages and aims to produce fine material to liberate ore from the minerals. The modelling and simulation of such processes are well established using static process models (King, 2001; Napier-Munn et al., 1996). A recent development in the dynamic modelling for such processes has shown further increase in fidelity compared to the static process models (Asbjörnsson, 2015). The developed simulations can be utilized to design, operate and control mineral processing plants based on the requirements of users (Bhadani et al., 2017). Typically, the requirements in the operation of the comminution process are conflicting in nature, as for instance, reduction of power draw by process units, maximization of production of fine materials, and increasing utilization of the process units. These conflicting requirements leads to a Multi-Objective Optimization (MOO) problem to operate a mineral processing plant. The MOO problems are normally referred to as non-linear problems and its fundamental understanding with respect to process behaviour is difficult to achieve."

Jan 1, 2018

By A. Y. Senchenko, Y. V. Kulikov

"The most common technique for selection of grinding equipment is the Bond method implying determination of a ball mill work index (BWi). The method is perfect for greenfield projects where a ball mill must be sized to grind an ore to 80% passing 75-100 µm. Finer grinding will require application of specific correction factors to a standard equation since initially the method was not designated for sizing of fine (minus 75 µm) grinding mills. Significant issues are related to selection of grinding equipment for treatment of originally fine materials when the standard procedure is not applicable. In 1984, Levin published his special technique titled as “A proposed test for the determination of the grindability of fine materials”, where he offered to use the standard Bond ball mill for determination of a specific grinding energy. However, this method did not meet with wide recognition. In 2017, Institute TOMS under guidance of JKMRC’s specialists performed a testwork aimed at verification of a new universal technique for determination of grindability of initially fine materials. An object was to test three aged tailings samples for the subsequent modelling of comminution circuit and evaluation of potential throughput of the existing ball mills with final grind size of ?80 passing 53 µm. In parallel with development of the universal approach, TOMS’ specialists carried out tests according to the Levin method in order to compare the data resulted from two methods. The results from lab ball mill testing on three products following the alternative test methods are presented in this paper along with the testing methodology and results analysis. Specific energy was calculated for regrinding of the materials to the required size. Difference of the examined methods and assessment of their applicability for sizing of full-scale equipment are explored."

Jan 1, 2018

By Rong Fan, Andrea Gerson

"The small recovery of Ag, often in the order of 50%, by traditional flotation and leaching process strategies is closely related to the complicated and heterogeneous nature of Ag-bearing minerals with Ag typically being associated with numerous minerals within any given ore-body. Moreover, grain sizes may be extremely fine with micron-scale common. In order to design cost-effective Ag-bearing mineral flotation and leach recovery strategies it is firstly necessary to characterise the speciation of Ag and its correlation with other elements, e.g., Cu, As and Sb, within the ore matrix and process streams. The traditional QEM-SCAN analytical approach can prove problematic for some mineralogies due to difficulties in recognising degrees of crystallinity, polymorphs, complex solid solution series, high value trace element mineralogy, very fine grained materials; and the requirement for a comprehensive data base. Moreover, there is difficulty ‘seeing’ either surface films or surface contaminants which can both lead to poor flotation performance. There is therefore clearly a need to develop confirmatory and complementary approaches when these uncertainties arise. Synchrotron X-ray microprobe analysis provides a powerful tool for the mineralogical characterisation of finely segregated heterogeneous Ag-containing materials. These measurements enable comprehensive characterisation of the Ag-bearing components using synchrotron microprobe X-ray fluorescence mapping (µ-XFM), X-ray diffraction (µ-XRD) and X-ray absorption spectroscopy (µ-XAS). Further analytical strength is provided by principal component analysis of laboratory ToF-SIMS data which enables the statistical identification of correlated surface species enabling examination of surface chemical characteristics responsible for mis-reporting of Ag containing components within flotation streams. We describe the application of these techniques to a selected Ag-containing feed and tail and demonstrate how these compliment and extend traditional analytical methodologies."

Jan 1, 2014

By Hristo Stanchev, Veselin Mehandzhiyski, Sashka Kozhuharova, Stefan Stamenov, Alexandar Penchev, Nikolay Nestorov, Velika Stamatova, Ekaterina Todorova

"This article presents the results of comprehensive research on the quantitative distribution of gold content in the raw ore and tailings from the flotation enrichment process at the Ellatzite Med plant. The study is a quantitative and qualitative determination of the presence of gold in the ore processed by Ellatzite Med AD, as well as its behavior and distribution in the various metallurgical products of the flotation process. The representativeness of the samples taken is ensured by the frequency of sampling: four work shifts of sampling on different days within a period of four consecutive weeks. The form of gold present is determined both in the analyzed samples and in separate fractions - granulometric, magnetic, electromagnetic, heavy and light. A summarized diagram presents the phase distribution of gold in the final products of the dressing process. The results obtained are used for further analysis and evaluation of the actual technological parameters of the gold. It was established that an increase in the initial gold content, respectively in the content of native gold in the raw ore, with the current process, leads to an increase in gold losses, mostly in the native gold phase. The conducted analysis of the results from the comprehensive tests on determining the form of gold present in the various enrichment products gave rise to further research with the use of a Knelson centrifugal concentrator."

Jan 1, 2014

By Buks Kruger

"After the milling and flotation of the platinum bearing ore, the flotation concentrate is electrically smelted in 6-in-line electric arc furnaces and the resulting furnace matte treated in Peirce Smith converters to remove the iron sulphide. The iron free (less than 1% Fe) converter matte is then granulated and sent to the Base Metals- and Precious Metals Refineries for further processing.During the smelting and converting processes two distinct gas streams are produced.The Peirce Smith converter off gas contains 4% - 9% SO2 which is treated in a conventional Sulphuric Acid Plant to produce sulphuric acid (H2SO4).The electric furnace off gas contains 0.9% SO2 and was (until September 2002) vented through a 91 meter high stack to atmosphere.Off gasses which contain less than 3% SO2 is difficult to handle and quite a few processes had been developed over the years to cope with this gas. A broad spectrum of process suppliers and technology approaches is available and the different technologies can be divided into a few main approaches i.e.Scrubbing of the off gas with an alkaline solution to produce an environmentally friendly and stable waste product which can be discharged onto a tailings dam or permanent landfill site.Physical absorption of the SO2 into a chemical solution to produce high quality chemically pure process chemicals.Catalytic reaction of SO2 with O2 to produce SO3 which is absorbed in water to produce sulphuric acid of less than 90% strength.In October 2002 Impala Platinum commissioned a Sulfacid Plant at its Smelter in Rustenburg which recovers the SO2 from the electric furnace off gasses into a weak sulphuric acid solution.The Sulfacid Plant technology is widely used in the paint pigment industry. This is, however, the first application of the technology on electric furnace off gas.The furnace off gasses contains flue dust which is removed in electrostatic precipitators. The gas exiting the precipitators normally still contains between 40 mg/Nm3 and 60 mg/Nm3 dust and passes through a quench-scrubber before entering the reactors. The quench-scrubber cools the electric furnace offgas down from ± 200 °C to 60 °C and act as a final dust removal stage."

Jan 1, 2003

By A. An. Mushketov, A. Al. Mushketov, N. A. Sopina

"INTRIDUCTION At present, more and more metallized raw materials with a metallization degree of not less than 80% are used in the smelting of steel. The main quantity of this raw material is produced in furnaces of mine type. Advantages of this type of raw materials for metallurgical processing are low levels of harmful and slag-forming impurities and a high content of metallic iron. At the same time, the cost of smelting raw materials and obtaining high-quality steels are reduced. In addition to the undoubted merits of metallized raw materials, there are high requirements for the quality of iron concentrates, which are the starting material for metallization: the mass fraction of acidic oxides should not exceed 3%; The mass fraction of iron should not be less than 69%, mass fractions of harmful impurities (phosphorus, arsenic, sulfur, copper, etc.) should not exceed 0.02%. These requirements are dictated by the fact that the recovery of burned pellets is carried out by gas in a solid phase. In this case, the empty rock and harmful impurities from the metal are not separated and sent to the steelmaking unit, increasing the heat consumption for heating and worsening the quality of the steel. The combined production of high-quality concentrate and metallized raw materials requires a large capital outlay from the enterprise, which in the future can be compensated for by increased profit from the sale of more expensive marketable products. At present, in the territory of Russia and the CIS countries Lebedinsky mining-and-processing integrated works is the only enterprise that carries out the entire chain of operations for the production of metallized raw materials, starting with the production of high-quality magnetite concentrate with a mass fraction of iron of 69.5% and ending with the production of a metallized product in the form of hot briquetted gland. JSC «SSGPO» is the largest iron-processing enterprise in Kazakhstan, which processes about 40 million tons of ore per year and receives 16 million tons of concentrate per year with a mass fraction of iron 66.0-66.5%. The technological scheme existing at the concentrator of JSC ""SSGPO"" includes the crushing of the feed ore to the size of 20-0 mm; dry magnetic separation operation; three reduction stages to a fineness of 90-95% kl-0.071 mm; operation of desliming, wet magnetic separation and filtration of the concentrate. Dry magnetic separation of the feed ore makes it possible to remove from the process of 19.6% of the tailings with a mass fraction of the total iron 12.5%, of magnetite 2.2%. The first reduction stage is carried out in rod mills with the volume of 40 m3 to a size of -1.6 + 0.0 mm. The first stage of wet magnetic separation is carried out in counterflow magnetic separators PBM-P-150/200L. The magnetic product of the first stage of WMS is classified in hydrocyclones; sands enter the second reduction stage into central discharge ball mill 3600 × 5000. Runoff of mills enter on the second enrichment stage in counterflow magnetic separators PBM-P-150/200L. The magnetic product enters the classification of the second stage, forming a closed cycle. Mass fraction of the class -0.071 + 0 mm in classifications runoff of the second stage is 70-75%. The second stage classifications runoff is transported toWMS-III operation in semi-counter separators PBM-PP-120/300. The magnetic product of the third stage enters the classification of the third stage. Granular residue are transported to the reduction of the third stage into central discharge ball mill 3600 × 5000. The mill runoff enters the third stage of classification, forming a closed cycle. Classifications runoff of the third stage enters on deslimation. Deslimed product is sent for fine screening to the crasher «Derrick» 2SG48-60W-5STK with a cell size of 0.1 mm. Top size of crasher is sent to regrinding. Undersize with a mass fraction of the class -0.071 + 0 mm 90-95% is fed to the wet magnetic separation of WMS-"

Jan 1, 2018

By S. K. Pan

The process flow-sheet adopted in treating hematite iron ore in India through wet circuit generates not only 15-25% slime of Run-of-Mine (ROM), but also results in loss of very high quality fine iron ore particles along with it. As the reserves of hematite iron ore is depleting, it is necessary to explore the possibility of upgrading other types of low grade iron ore and slime for recovery of iron minerals; extensive research in this field is being carried out. While beneficiation of low grade ore is yet to be established, slime beneficiation has been quite successful and many installations of slime treatment plant are underway. In SAIL mines, the slime is mainly the discarded particles from Classifiers, which are less than 0.2 mm sizes. R& D initiative has been focussed on the beneficiation of the slimes (49-60% Fe, 3-10% Al2O3 & 4-10% SiO2) of Dalli mines to generate concentrates assaying 62-64% Fe, 2-3% Al2O3, 3-4% SiO2 and a few innovative facilities for the same has been introduced at this mines of Bhilai Steel Plant (BSP). At Dalli mines, the slime is of very poor quality. A typical slime analysis assays 48.54% Fe, 15.1% SiO2, 8.5% Al2O3 and consists nearly 60% (by wt.) particles less than 38 micron. Slime analysis revealed substantial quantity of very high density mineral particles, those causes jamming of Thickener due to faster settling. A novel technique has been implemented to classify the concentrate ore particles from the gangue mineral particles by processing through Fluidized Bed Classifier (FBC) system, which is a gravity concentrator, to treat 50% of the slime generated and the rest is treated through de-sliming hydro-cyclone followed by Medium Intensity Magnetic Separator (MIMS). A special self-vibrating launder has been designed and introduced into the system to recover tiny iron ore particles, which could not get captured by the permanent Neodymium rare earth magnet in MIMS. The classified iron mineral particles from FBC are further treated in a battery of hydro-cyclones followed by modified Slow Speed Spiral Classifier (SSSC) unit. Multiple feed entry system to the SSSC unit is unique and use of particular feed entry point depends on the desired quality of the product and thus converted to a beneficiation equipment rather than mere de-watering unit. By processing slime in FBC system, the valuable iron ore particles with 62.5% Fe, 5.2% SiO2, 2.23% Al2O3 has been recovered from the slime at a material yield of 30%. And very high valued concentrate particles with more than 65% Fe has been sorted out through the magnetic separation route. The overall extra production of beneficiated slime concentrate is 40-45 tph with 63-64% Fe from a slime feed of 120-130 tph solid. This paper outlines few new approaches in iron ore slime beneficiation at Dalli mines for maximum recovery of valuable minerals. Keywords: fluidized bed classifier (fbc), iron ore slime of dalli mines, medium intensity magnetic separator, slow speed spiral classifier (sssc)

Sep 1, 2012

By D. G. Hulbert

"Mineral processes are complex operations that have been modelled, controlled and simulated by diverse technologies. A review is given of some models of mineral processes in the literature. A new variation of a dynamic process model of flotation is presented. Process models, describing real and relevant physical variables, give a good understanding and good qualitative simulations, but can sometimes require prohibitively difficult and extensive parameter estimations. Process control is usually best done on operational plants by the fitting of system models, which can home in on the plant?s observability, controllability and optimisation. System models can be of a form amenable for use in appropriate techniques for controller design and implementation. The control of milling circuits is discussed in some detail. While simulators use models to predict dynamic or steady-state information, part of their strength lies in their ease of use and their ability to test different types of specifications. Some results are given for a flotation circuit simulator that can be made to solve virtually any permutation of specifications.INTRODUCTIONThe development and application of appropriate technology can lead to better operation of mineral processing plants in industry, so that substantial benefits can be obtained from improved throughputs, efficiencies and product qualities. This paper addresses some of the principles and methods used in the quest for the development and exploitation of such technology. Although the design of processes is often the motivation for modelling and simulation, this paper also targets the use of modelling and simulation for the control and optimum operation of mineral processes. The two processes given the most attention here are flotation and milling.Technologies used in mineral processing range from simple to very complex. Simple technical principles, such as mass and component balances, can yield some simple and effective strategies for modelling and control. However, minerals in particulate form have such complex physical and chemical properties that there appears no end to the complexity that emerges, as more and more factors are taken into consideration in the pursuit of better results and understanding. The situation is aggravated by the complexity of mineral processing plants, which have spatially variable conditions within process units, and complicated interactions between these units."

Jan 1, 2003

By Jiajun Geand, Shuli Wang, Baodong Pan, Xueqi Cui, Guangwei Zhang, Jipeng Sun

Gravity-fed three-product dense medium cyclone(GTDMC)is usually used as the main coal washing equipment in coking coal preparation plant. It can produce three products with a low density suspension at the same time. Raw coal and dense medium are fed separately into the cyclone. Only the qualified low-density medium suspension is pumped into the cyclone while the raw coal is fed into the first-stage 1200mm cyclone axially at the top end by gravity. The 1200mm cyclone with a cylindrical form is for low-density separation. The clean coal with light density and slower-settling velocity moves directly towards the low pressure zone along the axis and is carried through the vortex-finder to the overflow. Only the heavy products pass through the "separating zones" to the wall of 1200mm cyclone and then migrate into the series-connected second-stage 850mm cyclone through the tangential outlet. The medium suspension from the first-stage cyclone is thickened and contains more magnetite coarse particles. The second-stage cyclone typically consists of a cylindrical section and conical part. These are all favorable for the second-stage cyclone to separate at a high density. Production practices show that the clean coal and the gangue rarely mixed in the middling, the lower limit of the separation is 0.2 mm, the Organic Efficiency and the Ecart probable of the first stage is 98.30% and 0.026 kg/L respectively.

Jan 1, 2014

By N. D. Dementieva

Based on lab and pilot-plant tests to recover gold, silver and lead of a Russian deposit, a collective and flotation concentration flow sheet with lead and sulfide concentrates was proposed. The type of the deposit is gold-sulfide-quartz-bearing. The recovery of gold, silver, and lead to a lead concentrate was 47.4%, 68.1% and 70.7%, respectively. The grade of gold and silver grade was 170 g/t and 372 g/t, respectively. The mass percent of lead, zinc and arsenic mass percent was 41.7%, 0.34% and 0.63%, respectively. The recovery of gold and silver recovery to a sulfide concentrate was 50.1% and 28.8% at the grade of gold 20.5 g/t and silver 66.2 g/t. Sulfide concentrate with arsenic mass percent ~3% was biooxidised followed by CIL and obtaining metal at the site as well as zinc concentrate from bioleaching solutions with zinc mass percent 45% at its 64% recovery. The total gold and silver recovery using a developed technology with the account of their treatment at a polymetallic plant was 92.2% and 93.7%, respectively.

Sep 1, 2012

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 S. S. Yu

In this paper, the producing process of using V2O3 as raw material to obtain vanadium nitride was analyzed through the means of thermodynamic. The analysis shows that conversion follows the principle of reduction step by step in the conversion process of V2O3. The temperature of the reaction system has prominent influence on the nitrogen content of products, and the reaction is very sensitive to temperature. As raising temperature, the fine grain structure of the nitrides is more evident, and the grain size of nitrides increases. At 1703K, the nitrogen content of the products tended to be constant after soaking over 3 hours.

Jan 1, 2014

By Brian Loveday, Sandile Nkwanyana, Indresan Govender

"Recent batch experiments by the authors in a pilot scale ball mill (Ø = 0.6m) have demonstrated that a partial replacement of the ball charge by pebbles (25 % pebbles; 75 % steel balls) optimally reduces the ball and power consumption without altering the rate of production of fine material (passing 75 microns). At higher pebble volumes, the production rate of fines was reduced progressively. With the 25/75 composite charge a saving of 13 % in power consumption was achieved, and a saving of 25 % in steel ball consumption is implied. A partial replacement of steel balls by pebbles reduces the overall density of the grinding media in the charge. Taking into consideration that the production rate of fines is usually proportional to the bulk density of the charge in the mill, it would be expected that a composite charge (e.g. 25/75) would coarsen the grind and consequently reduce the rate of production of fines. Pebble wear contributes a small proportion of fines and it doesn’t provide a full explanation of why the 25/75 composite charge has no (or minimal) adverse effects on the rate of production of fines. Clearly, the production of fines across the mill is directly related to the shear and compressive power dissipation density. Accordingly, we hypothesise that the spatial power dissipation distribution meeting the minimum requirements for fines production— at the so-called active regions—are equivalent, or minimally comparable, for both the 25/75 composite and 100 % ball charge operating conditions. To test the hypothesis, we performed DEM simulations to analyse power dissipation in the active regions. 1. INTRODUCTION Comminution remains to be the most expensive process in mining operations, particularly because the energy consumed in this process accounts for 30-70 % of the total cost of a mining operation (Nadolski et al, 2014). Optimization of comminution circuits has been focussed on reducing capital and operating costs and maximising throughput capacity. For existing operations, it is often a challenge if the optimization process recommends retrofitting new ‘major’ equipment. The challenge arises from new capital cost and the difficulty of retrofitting in an existing circuit, while maintaining production (Major et al, 2001). Thus, for existing mining operations, optimization of comminution (cost and throughput) is often limited to operating conditions and/or addition of auxiliary equipment (such as pebble crushers, additional screens and high pressure grinding rolls (HPGR)) (McIvor and Greenwood, 1996; Hart et al, 2001; Powell et al, 2015b)."

Jan 1, 2018

By Héctor X. Toro, José Francisco Cabello, Douglas Batista, Álvaro Videla, Claudio Luiz Schneider

The Minas-Rio Project, located in the state of Minas Gerais, Brazil, is currently under construction. The new plant will have a regrinding circuit that uses VertimillTM. The objective is to process itabirite iron ores and it is expected that the consumption of media will represent a large part of the plant operating cost. Many studies in the literature indicate that the size of the grinding media directly influences the grinding efficiency. The size distribution of the charge media is related to the surface area of the charge. In this study, a sample of itabirite iron ore was tested with respect to grindability in a laboratory scale ball mill. The test mill was equipped with a torque device to accurately measure power consumption, as required for the determination of energy specific kinetic parameters. Five tests were carried out with different sizes of steel balls and with SICAM (sub-inch Cast Media). The size distributions of the feed and product of the several grinding tests were used to calibrate population balance model parameters for each condition. The results confirmed that the ball charge with smaller diameter is the most efficient among the different media charge tested.

Jan 1, 2014

"The research aimed at solving the problem of measuring instantaneous local physical quantities for multiphase flows in mineral processing, which are common in minerals industry and with significant challenges. Due to the lack of proper measurement tools currently in minerals industry, multiphase flows (such as in flotation cell) are treated as in a “black-box”. It is crucial to develop measurement technique by which the acquired processing data can be used for process optimization and control. By measuring the conductivity distribution across a measurement area, Electrical Resistance Tomography (ERT) has been adopted by many researchers to monitor and investigate many processes involving multiphase flows in other industry sectors. A compact ERT probe was built and then used to measure the conductivity distribution within a few flotation machines. In a flowing foam flotation column, the results showed that ERT can accurately measure the change of liquid content (high conductivity fluid distribution). In another part of work, based on the Green-Kubo relations, ERT can measure turbulence via the fluctuation of conductivity caused by bubbles moving through the measurement area, changing the density of the fluid. The tests with the Metso 3 m3 RCS flotation cell were also carried out for turbulence measurement under different air rates and impeller speeds. The results of flotation cell from ERT measurement showed that varying impeller speed had more pronounced influence than changing air rate. When impeller speed is increased, the size of the high turbulent zone increases. ERT is a powerful technique that has the potential to be used for a wider range of applications. The future work will be carried out with more case studies and expanded to more processes such as leaching process, high temperature flows in further downstream production chain (steel making process and alloy manufacturing process).INTRODUCTIONMultiphase flows constitute a majority of the naturally-occurring and industrially-relevant flows, especially in mineral processing. Some of the measurement techniques have been used for the study of fluid characteristics. Optical techniques such as Laser Doppler Anemometry (Kyselaa et al., 2013) and Particle Image Velocimetry (Nobach and Bodenschatz, 2009) can produce accurate measurement results with high spatial and temporal resolution, but their applications are limited to transparent flows. Hot wire probes (Amini et al., 2013) have high spatial and temporal resolution in turbulence quantification, but they are susceptible to environmental factors."

Jan 1, 2018