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By H. Tiefel, M. Schneider, T. Neesse, J. Regler, J. Dueck, F. Donhauser

In practice the advantages of high-quality hydrocyclone separation are often reduced due to varying feed suspension properties, solids concentrations and particle size distributions. Control systems of large hydrocyclones are usually fitted with controllable underflow nozzles, which is not practical for small hydrocyclone batteries. Therefore, a new control system for a battery of hydrocyclones with a nominal diameter of 150 mm was invented at the LUR in cooperation with AKW Apparate und Verfahren GmbH & Co. KG. This process was developed for bentonite slurry regeneration associated with tunnel excavation using bentonite slurry as a transport aid and lubricant.

Jan 1, 2003

By F. Karakas

In this investigation, one of the most energy consuming stage of the cement manufacturing process, grinding stage, was studied. The aim of the study is to reduce the energy consumption. Optimum operating parameters were determined. Experimental studies were performed at three differ-ent stages. Grinding of limestone, clay and marl which are the main components of the cement, to approximately below 90 microns, was the first stage of the cement grinding. At this stage, effect of feed size and ball charge were investigated. At the second stage, the Bond work index of clinker and additives (slag, trass, limestone and gypsum) was found separately. After forming composite cement with clinker and additives, the Bond work index of this mixture was also determined, thus the results of separate grinding and grinding of mixture were compared. The Bond work index of mixture was found as 13.59 kWh/t, while the arithmetic mean of the Bond work index values of components was 14.90 kWh/t. Finally, clinker and additives (slag, trass, limestone and gypsum) were ground under the same conditions. At this stage, laboratory type of ball mill was used in order to understand grinding characteristics of the cement components. As a result of the experiments, it was found that energy consumption for the grinding will be lowered if the mills with 38 % ~ 40 % ball charge are used in the cement grinding. Moreover, grinding with mixture of clinker and additives gave better results than separate grinding of these components in terms of energy consumption.

Jan 1, 2014

By S. L. Zheng

The compound material of Nano-TiO2 Supported on the diatomite was prepared by the hydrolytic method with purified diatomite and TiCl4. The compound material was characterized by SEM, XRD, TEM, EDX, XPS, and the application test of the compound material was studied. The characterization test results showed that the Nano-TiO2 was coated on the surface of diatomite, the crystal of TiO2 is anatase, and the average crystal size is 12 nm. The pore diameter was reduced, but pore volume and surface area of the compound material are increased after Nano-TiO2 Supported on the diatomite. The application test results for treating coking waste water and formaldehyde gas show that the compound material of Nano-TiO2 / diatomite has adsorption and photo-catalytic function and strong degradation performance for phenol and formaldehyde.

Jan 1, 2014

By D. Jamróz, A. Surowiak, T. Niedoba, P. Pieta

"The separation of coal material of three types of coals originating from three various Polish hard coal mines (types 31, 34.2 and 35, according to Polish nomenclature, which were steam coal, semi-coking coal and coking coal) into particle size fractions and then into particle density fractions was done and then the following parameters were measured for each particle size-density fraction: combustion heat, ash contents, sulfur contents, volatile parts contents, analytic moisture. In this way a 7-dimensional vector of data was created. Using methods of factor analysis the important features of coal were selected, which decide about their membership to individual types. To evaluate the appropriateness of the applied method the Bartlett’s sphericity test as well coefficient of Kaiser-Mayer-Olkin (KMO) were used. To select important factors the Kaiser criterion and Cattell’s scree test were used. The obtained results were compared with the results obtained in previous works by means of observation tunnels method. The results showed which particular features are crucial to define the type of coal what is also important to select appropriate method of its enrichment.INTRODUCTION Coal extracted from the mine is often a mixture of coals of various quality originating, for example, from various coal layers. One of the most important issues is to determine its quality, what means to verify if it fulfills certain requirements. Usually, such parameters as combustion heat, ash contents, sulfur contents, volatile parts contents and analytic moisture decide what the coal quality is (Drzymala, 2009). Such investigations are expensive and time consuming. That is why it seems to be important to determine the mutual connections and interactions between them what would make possible to reduce the amount of the necessary parameters. This issue was already investigated with successes in several works [Jamróz and Niedoba, 2013; 2014; Niedoba, 2015]. This work is another approach to this problem. Here, the investigation of possible reduction of researched parameters was done on the basis of the factor analysis. The obtained results confirm the earlier observations."

Jan 1, 2018

By Shibayama A.

In this research, an investigation of a process to selectively remove arsenic (As) and antimony (Sb) contained in enargite (Cu3AsS4) and tennantite/tetrahedrite ((Cu1,Fe)12(As,Sb)4S13) copper resources by leaching and precipitation were performed. First in the leaching process, the target was to selectively leach As/Sb and reduce their contents in the ores to <0.5 wt% followed by a second process to remove As/Sb dissolved in solution for environmental control. Enargite ore contained 3.65 wt% As while tennantite/tetrahedrite ore contained 5.40 wt% As and 4.85 wt% Sb. Alkaline leaching using NaHS?NaOH media at varying experimental conditions (temperature, pulp density, time, reagent concentrations) were performed to investigate the process. As/Sb precipitation studies were also performed to control high As/Sb concentrations in leach solutions by using elemental sulphur (So). Results from leaching studies showed that over 99% of As/Sb in the impure copper ores can be removed and their contents in the final solids reduced to <0.5 wt%. It was also established that such very high leaching could be achieved at 80°C within 1?6 h and pulp densities as high as 1000 g/L. The study also revealed that leach solution containing very high As/Sb concentration ranging from 5 to 20 g/L can be used as fresh solution for leaching of fresh ores until concentrations exceeding 35 g/L when it was sent to precipitation circuit for As/Sb removal. Addition of elemental sulphur at 90°C and fast cooling to 30°C allowed over 60% As/Sb precipitation and removed as Na3AsS4 and solution with reduced As/Sb concentration to leaching circuit for continuous use. Keywords: Enargite; Tennantite/Tetrahedrite; Selective Leaching; Precipitation; Sodium hydrosulfide;

Sep 1, 2012

By S. Serranti

A fast, reliable, and low cost characterization of ore minerals products, as they result from different processing actions, represents one of the most challenging targets in the mineral processing sector. Today different techniques are available according to different sampling strategies and analytical principles. In this paper, the possibilities offered by the adoption of hyperspectral imaging based sensing units working both at micro- and macro-scale are presented and discussed. According to the different phases and stages of ore minerals and products characterization, and starting from the analyses of the detected hyperspectral firms, it is thus possible to derive useful information about mineral flow stream properties and their physical-chemical attributes. This last aspect can be utilized to define innovative process mineralogy strategies and to implement on-line procedures at processing level. The present study discusses the effects related to the adoption of different hardware configurations, the utilization of different logics to perform the analysis and the selection of different algorithms according to the different characterization, inspection, and quality control actions to apply. Keywords: process mineralogy, hyperspectral imaging, NIR spectroscopy, surface mapping, textural analysis, quality control

Sep 1, 2012

By A. V. Bogdanovich

In diamond ores processing, final waste tailings size, rejected to dump, is one of the most important parameters. On one side, it is necessary to minimize losses of diamonds, whose size exceeds 1 mm, on the other side ? to provide for the plant high throughput and sufficiently low capital and energy costs, which is in greater part connected with disintegration process. Extensive laboratory, pilot-scale and commercial-scale dressability studies of different types of diamond ores have been performed at JSC ?Mekhanobr Engineering? in recent years. With that, special consideration was given to determination of the required ores? disintegration size that would provide for a high recovery of diamonds. In diamond ores processing, in order to exclude breaking of large diamonds, stage disintegration is used with regrinding of light fractions and heavy fraction X-ray fluorescent separation tailings. On account of rather weak bonds of diamonds with enclosing minerals, in crushing and grinding of diamond ores, selective disintegration takes place, with aggregates? breakup along plane surfaces of least bonding, which facilitates liberation of diamonds and their transition to free state. Heavy components losses with different sizes of final dump tailings were studied in processing of large samples. It was established, that in order to almost completely exclude losses of heavy components over 1 mm size, light fractions had to be ground to 2.5-3 mm size, while X-ray fluorescent separation heavy tailings of -15+3 mm size do not contain diamonds larger 1 mm in aggregates, and their regrinding does not increase total recovery of diamonds. On the basis of the conducted studies, relationships regarding heavy components and diamonds losses with respect to diamond ores final disintegration size were obtained, providing for more rational organization of the ores disintegration and processing flow sheet. Keywords: diamond, waste tailings size, disintegration process, recovery of diamonds

Sep 1, 2012

By N. S. Voiloshnikova

Large-scale continuous ?Resin-In-Pulp? process tests were conducted at Irgiredmet. The object for testing was the sample of oxidized gold ore from one of Siberian deposit. Weak-base ion ex-change resin PuroGold was used as adsorbent. The duration of ?Resin-In-Pulp? tests was sufficient for a completing of three cycles ?Adsorption/Elution?. Gold in feed was 0.95 mg/L. Gold in solid phase of adsorption tails? 0.065 g/t. Gold in liquid phase of adsorption tails? 0.026 mg/L. Total gold in adsorption tails ?0.11 g/t. Gold recovery ?94.3 %. The use of regenerated resin had practically no effect on gold losses with adsorption tails. Alkaline cyanide solution (NaCN-20g/L, NaOH- 5g/L) was used as eluent for gold elution from loaded resin. Elution temperature ?60 °C. Number of eluent bed volumes passed ?10. Loaded resin analysis was following (g/ton): Au? 1700~1250; Ag? 400~460; Cu? 250~450; Zn? 5100~9600; Fe? 860~1200. Elution efficiency: Au? 95.3%~97.8%; Ag? 84.0%~88.0%; Cu? 84.0%~88.0%; Zn? 97.0%~99.0%. Although high zinc resin loading was shown zinc was eluted efficiently. The adsorption properties of fresh PuroGold resin, PuroGold resin after 3 cycle ?Adsorp-tion-Elution?cycles in comparison with AM-2B resin were tested. It was shown from adsorption isotherms that selectivity of PuroGold resin slightly less in comparison with AM-2B resin mainly due to its higher zinc adsorption properties. It was founded on base of test results that adsorption properties of PuroGold resin was practically constant during three ?Adsorption/Elution? cycles. Gold may be efficiently recovered by resin tested. There were no difficulties during gold elution from loaded resin and its regeneration. PuroGold resin was recommended for industrial use in RIP process. Process design criteria were developed and plant design is on progress at the moment.

Jan 1, 2014

By G. Semenchenko

Heterotrophic microorganisms Pseudomonas aureofaciens, microscopic fungi Fusarium sp. and their combinations with some chemical substances were used for gold leaching from refractory ore and flotation concentrateof Akbakaj deposit. All biological additives raised the speed of noble metals dissolution. The best results of gold extraction from ore were in the presence of bacteria or their associations with other solvents and from flotation concentrate in the presence of fungus - 30 % of additional amount of gold. The maximum extraction of gold speed value was during the first 8 hours of process. The electronic-microscopic researches of the ore samples showed almost complete decay of pyrite and arsenopyrite under bacteria influence whereas at chemical leaching most of these minerals stayed uncrushed. The presence of microscopic fungi in flotation concentrate during leaching provided full distraction of pyrite, but some crystals of antimony and arsenopyrite were undestroyed. During cyanide leaching of flotation concentrate there were accumulation of antimony and incomplete pyrite decomposition. Keywords: gold bioleaching, bacteria, fungi, complex solution

Sep 1, 2012

By D. R. Nagaraj, Raymond Farinato

Water constitutes one of the most valuable resources employed in mineral recovery and processing. Identifying potential problems encountered in mineral processing in waters unusable for drinking or agriculture (including seawater and even hypersaline waters), understanding chemical factor interactions, and optimization of flotation reagents will greatly expand our ability to create more sustainable beneficiation technologies. The current paucity of our knowledgebase regarding high salinity effects on flotation clearly signals a need for a significant research effort. We report here results of a study designed to probe effects of pulp chemistry on metallurgical performance in the flotation of Cu and Cu-Mo ores in saline waters. The results clearly demonstrate that pH (more correctly dosage of pH modifier to target a pH set point) has the most significant effect on Mo recovery when using seawater. This is linked to the formation/precipitation of Mg(OH)2 when pH = 10.3 (in seawater). The type of pH modifier used, NaOH or Ca(OH)2, had no impact on Cu or Mo recovery, indicating that Ca2+ ions were not involved in any reduction in Mo recovery in the pH range of 9-11. Our results in tap water spiked with either Ca2+ or Mg2+ ions in the same pH range (controlled by NaOH), confirmed that Ca2+ ions had no effect on Cu or Mo recovery, but that addition of Mg2+ ions had a severe adverse effect on Mo recovery at pH = 9.5, and to a lesser extent on Cu recovery. The onset of Mg(OH)2 precipitation occurred at a higher pH, and the adverse impact of Mg(OH)2 on Cu recovery (and perhaps Mo recovery as well) was less, in sea water than in tap water spiked with Mg2+. These effects are attributed to the mitigating role of the high electrolyte concentration, notably NaCl.

Jan 1, 2014

By Z. D. Tan

The continuous digestion technological conditions of phosphate tailings with high magnesium content in sulfuric and phosphoric mixed acid is studied in this paper. The influences of excess coefficient of sulfuric acid, weight liquid to solid, reaction temperature and time on conversion of P2O5 and MgO are discussed. The influence of infiltration capacity of phosphogypsum by the concentration of liquid-phase SO3 is discussed too. Under the optimal technological conditions, the conversion of P2O5 is 95.56% and MgO 98.63%, the filtration rate of phosphogypsum increases with the increasing of liquid-phase concentration of SO3, the optimal apparent concentration of SO3 is 0.135~0.14g? mL-1 in liquid-phase. The filtration rate of phosphogypsum is 1473kg? m-2? h-1. N-P-Mg compound fertilizer was produced by adding magnesia powder and inflating ammonia in filtering medium.

Jan 1, 2014

By Gorki Davila, Irineu Brum

"Brazil has large reserves of coal (32 billion tons) located predominantly in the south of the country. Despite the relative ease of exploitation, these resources have been underestimated as a source of energy. Currently the country&apos;s strategic planning aims to minimize the gap between coal and resources traditionally used in the Brazilian energy matrix. In this scenario the processing of Brazilian coal by flotation appears as a promising alternative, having been successful in mineral systems containing fine particles This paper aims to study the overall process of flotation for a specific Brazilian coal. The material used in this study consists of fine coal that is usually discarded as waste and deposited in the tailings dam. The objective is to recover carbonaceous matter and reduce the ash and contaminants grade. The variables analyzed were the influence of size particle, solids concentration in the pulp, the concentration of surfactants and frothers to be used. The results showed that it is possible, from a feed with around 65% of ashes, to obtain products with approximately 35% ashes with mass recoveries about 40%. The types of collector reagent and foaming employees result in different concentrates. This study also presents a preliminary analysis of the effect of water recovery in concentration parameters."

Jan 1, 2014

By Yuexin Han, Wenbo Li, Yan Shan, Yanjun Li, Shumin Zhang

"With the accelerating pace of resource extraction, the quality of resources is decreasing, and the old tailing dams which have served for several decades have become the focus of attention. The secondary recovery of valuable metals in the tailings is an important aspect of the comprehensive utilization of tailings. The average iron content of iron tailing is 8%-12% in China. The research aimed at exploring the low-cost and efficient technical route to recycle eastern tailings of Anshan iron mining area. The purpose of the research is to scientifically find the rational conditions of magnetizing roasting and to provide an increase in recovery and quality of concentrates. The eastern tailings of Anshan mining area belong to high silicon bearing iron tailings, iron mainly exists in form of hematite-limonite with an iron grade of 10.60%, the main component of gangue is SiO2 with a grade of 76.22%. In order to reduce the influence of the tailings on the environment, fluidized magnetizing roasting and low intensity magnetic separation for the eastern tailings of Anshan mining area were carried out to improve the utilization of the tailings. The results indicated that an iron concentrate with an iron grade of 65.30% and a recovery of 85.85% could be obtained under the conditions of gas flow rate 8 m3/h, H2 concentration 50%, fluidized magnetizing roasting temperature at 600? for 20s. Phase analysis, magnetism analysis and XRD analysis on roasted materials indicated that hematite-limonite could be transformed to magnetite during the fluidized roasting, then the effective separation of iron and gangues could be made easily by the weak magnetic separation. INTRODUCTION It is universally acknowledged that the grade of iron ore in China is low, the output rate of iron ore tailings is high, usually more than 60%. At present, the comprehensive utilization rate of iron ore tailings is low in China. Generally, the iron ore tailings are stockpiled in the tailings dam. The tailing dams not only occupy a lot of land, but also takes a lot of money to construct and maintain. In addition, the noxious substances in the tailings, such as residual flotation agents and heavy metals, have a severe impact on the ecological environment. There is little doubt that tailing dams have a visual impact on the environment due to their regular geometric shape. Iron tailings can be treated as compound mineral, which is an important component of comprehensive utilization of mineral resources, and is an has been widely concerned. Lots of scholars have done a large amount of research work on a large number of iron ore tailings. Since the iron mineral crystal grain size is fine and the iron grade is low, the iron tailings have failed to achieve good selection criteria."

Jan 1, 2018

By Bruce Mathema, Steven Huynh, Terry Cheng, Gerry Gomez

"The use of PM40N, a specialty precious metals promoter in conjunction with a standard Xanthate based collector was extensively investigated in the flotation of a complex, silver-bearing, lead-zinc ore containing naturally occurring graphitic gangue. The ore, considered difficult to treat with conventional reagents, was tested at plant scale to determine the impact of the promoter on silver recovery, lead grade and also on the amount of zinc misplaced to the final lead concentrate.Initial laboratory-scale rougher flotation testing implied significant improvements in the recovery of silver and lead with a marginal amount of zinc displaced. Subsequent mini pilot flotation tests further revealed that a gain in selectivity and recovery could be achieved by adjusting PM40N promoter dosage and incorporating a cleaner flotation step, further improving rejection of sphalerite. Plant trials resulted in an improvement of 3% in Silver recovery coupled with a 2% increase in recovered lead whilst maintaining lead grade in the lead circuit.To date, the use of PM40N as a promoter has enabled the processing operation to significantly increase its plant economics. The partial replacement of the standard Xanthate based collector has also reduced the overall quantity of Xanthate required in the standard circuit by approximately 10% - which is a positive impact on the environment. It is envisaged that further optimization of plant parameters will favor stable operation and continue to boost revenues generated by subsequent improvements in silver metallurgy."

Jan 1, 2014

By A. Gül

This investigation was carried out with low grade Murgul-Cakmakkaya copper ore once used to be dumped away as waste material. Sulphide minerals in the ore sample observed are chalcopyrite, pyrite, sphalerite and to some extent molibdenite; quartz, calcite and dolomite are the gangue minerals. The ore sample assays 0.28% Cu, 2.94% Fe and 3.36% S. Mineralogical study of the ore sample showed that adequate liberation of chalcopyrite for flota-tion was achieved below 100 µm. In flotation tests Aerophine 3418-A was the collector employed, NaOH or Ca(OH)2were the pH modifiers. Deactivators used were sodium meta bi-sulphide, starch, dextrin and lime. MIBC was the frother used throughout the tests. Test results showed that starch alone was the most suitable depressant to give the optimum metal content and recovery val-ues. Activated charcoal was used to adsorb excess collector species in the flotation pulp during cleaning stages After two stages cleaning of the rougher concentrate using starch as the depressant a copper concentrate assaying 21.2% Cu was obtained with 79.5% recovery while the tailings contained 0.01% Cu and metal losses were about 3%

Jan 1, 2014

By Z. Y. Lan

Bioleaching of marmatite with various mixed cultures of microorganisms was investigated. The experiments were carried out in shaking flasks with iron-free nutrient and the pulp density of 10% wt/vol at the temperature of 30?. The results show that zinc is preferentially leached before iron. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans is 62% in 18 days. The leaching rate of zinc with the mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans is nearly the same as that with the mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans (45% versus 50%). SEM and EDX analysis of the leaching residues indicate that a solid product layer composed of iron sulfide, elemental sulfur and jarosite accumulates in the mineral surface and becomes a barrier to the dissolution of marmatite. The bioleaching of marmatite follows the shrinking core product layer model. When the product layer increases and becomes insoluble, the leaching rate is controlled by the diffusion through the product layer and slows down. When the product layer decreases or becomes a porous layer, the leaching rate is controlled by chemical reaction and enhanced dramatically.

Jan 1, 2014

By C. Perez

In mineral processing plants it is important to estimate rock composition, size and grindability to improve control of the grinding process. It is well known that variation in ore grindability and size distribution directly affects mills power consumption and throughput. This paper extends a general machine vision approach for on-line estimation of rock mixture composition using color information. Our proposed rock lithological recognition method requires the following steps: division of each image into sub-images, color feature extraction using the Binary Quaternion-Moment-Preserving thresholding technique (BQMP) and support vector machines (SVM) for classification. The BQMP thresholding technique splits the image in two and chooses representatives of each half using the histogram as features. The statistical parameters of the color data can be expressed using the quaternion moments into the representatives. This method can be recursively applied to the sub-images, obtaining 5x2n features in n iterations. Once the feature vector has been computed, each vector is assigned to one of three classes using a classifier. The method was tested on a database containing 20480 sub-images (64x43 pixels) of five ore types as follows: massive sulphide (MS), disseminated sulphide (DS), net textured (NT), gabbro (G), and peridotite (P). These ore types were assigned to three grindability classes: soft (MS), medium (DS and NT) and hard (G and P). The database was divided in 2 subsets: 15360 sub-images used for training and cross validation and 5120 sub-images used for test. The classification accuracy was compared with a method previously published based on a mixture of principal components analysis (PCA) for color, and wavelet texture analysis (WTA) for texture feature extraction. WTA-PCA approach reached a 76% accuracy in test while our BQMP method reached 90% of classification accuracy using only color features. Experimental results show that our proposed method yields excellent results compared to previously published results. Keywords: rock classification, lithological classification, grindability estimation

Sep 1, 2012

By P. M. Solozhenkin, V. N. Kovalev

Russia is a global antimony market leader. The three major antimony production provinces are Sakha Republic (Yakutia), Krasnoyarsk Territory and Trans-Baikal Territory. Russia’s largest antimony resources are Zhipkozhinsky and Solonechensky deposits in Sakha Republic (Yakutia) and Olimpiadinskoe deposit in Krasnoyarsk Territory. This work demonstrates the efficiency of computer programs and chemical technology aimed at the study of the behavior of collectors used in the processes of flotation of antimony, arsenic and Au (I – III) minerals. The most promising collectors for the flotation of ores containing antimony and gold on the basis of P(V) and compounds with S, O and N atoms were chosen. The mechanisms of interaction with the mixtures of two or three components of collectors were studied. High recovery of antimony and gold was reached in the processing of Au-Sb ores of Sarulah and Sentachan deposits in Sakha (Yakutia). X-ray radiometric methods of separation of antimony ores of Trans-Baikal Territory deposits were proposed. In order to choose the most cost-effective solvents for hydrometallurgical processing of Sb, Au-containing concentrates the method based on clusters formation between transition solvents and antimony minerals was suggested. The nature of Au losses was theoretically revealed in the sulfide-alkaline process. On the base of computer simulation, the formation of various complexes of (KAu) types was developed, for example, hydrosulphidic gold, thiosulfates of gold - Na3AuS4O6, antimony and arsenic gold, trithiostibate (III) and trythioarsenate (III) KAu were produced. The practice of processing of goldantimony concentrates to produce high-quality antimony trioxide and antimony-gold containing alloy (AGCA) regarding the special conditions of the Far North region, were analyzed. The affinage of AGCA was recommended. Creative project development of antimony industry in Russia in order to produce antimony compounds and pigments, including pyriform compounds and flame retardants (antipyrenes) is discussed.

Jan 1, 2018

By William Skinner, Jonas Addai-Mensah, Keith Quast, David Robinson, Jason Connor

A review of the laboratory- and pilot plant-scale physical separation techniques for the beneficiation of nickel (Ni) laterites shows limited efficacy. To date, the only upgrade technique adopted commercially, prior to hydrometallurgical processing of Ni laterites, is the removal of a barren, coarse size fraction in the feed by classification. In the present work we investigated two low grade (~ 1%), goethite-rich Ni laterite ores’ upgrading by magnetic separation, attritioning/coarse, (lower Ni-grade) gangue rejection and flotation techniques. Low intensity (0.1T) dry magnetic separation at ambient temperature of raw samples and those pre-heated at temperatures up to 450 °C showed evidence of pay metal Co and Mn bearing asbolane and/or lithiophorite minerals pre-concentration in the magnetic fractions. Ni distribution, however, did not show any noticeable magnetic upgrade but followed the weight distribution. Other ore pre-treatment methods (e.g., desliming and sulphidisation) followed by froth flotation with anionic and cationic reagents also led to noticeable (~35%) Ni upgrade. This is due to the deportment of Ni across several gangue host mineral phases (i.e. Fe oxide/hydroxide and a range of silicate/aluminosilicate minerals). From chemical analysis, after disaggregation of ~ 1% Ni grade feed ore, coarse (-600 + 38 µm) and fine (-38 µm) fractions of ~0.6% and 1.3% Ni grades respectively, were also produced, suggesting that a significant upgrade in Ni content can be achieved by rejecting the + 38 µm fraction with the loss of <40% of the Ni. The ore mineralogy, particularly the complexity and high number of un-liberated Ni-bearing phases, greatly compromises physical separation methods for these ores, with the possible exception of screening after disaggregation of the fines inherent in the run of mine ores.

Jan 1, 2014

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