Search Documents

By W. Y. Gao

Diaojuntai Concentrator adopts a process of low intensity and high intensity magnetic separation and anionic reverse flotation, with all the concentrate from magnetic separation being treated by re-verse flotation to obtain a qualified final concentrate. The high reagent cost and energy consumption of the reverse flotation have led to a high concentrate cost. The test research on reducing the feed to the reverse flotation was therefore carried out. Based on the study of the properties of the ore sample, the concentrate of low intensity magnetic separation was screened at 0.076 mm and the undersize fraction was concentrated by concentrator with gravity and magnetic field. The results show that a qualified concentrate can be obtained at various rising current rate, pulsating current and power-on style, with the operation rate over 85%. The extraction of some part of qualified concentrate from the concentrate of low intensity magnetic separation by magnetic separation can reduce the feed to the reverse flotation by about 35% so as to reduce the production cost of concentrate.

Jan 1, 2014

By Carsten Gerold

The paper is giving an overview about successful operating Loesche Vertical ? Roller ? Mills (VRM) installations and summarises the main benefits of the dry compressive Loesche grinding technologies in Airflow- and Overflow-Mode. Some of these benefits are optimised energy efficiency of the grinding - classifying - circuits, increased mineral recoveries and decreased OPEX costs, at a parallel simplification of the process route. Within this paper the process values of the Loesche VRM are compared to existing or planned conventional grinding ? classifying circuits. Further advantages discovered in pilot trials and examples for new more efficient process route alternatives are given. The paper reports about production and pilot trial experiences obtained by crushing and grinding Iron Ore, Iron Ore Concentrates, Copper Shale, Copper Matte, Copper Slag, Titanium Slag, Tin Slag, Steel and Stainless Steel Slag with Loesche VRM.

Sep 1, 2012

By Robinson Irarrazabal, Edison Collinao, Rodrigo de Carvalho, Patricio Davila, Marcelo Tavares

"In recent years, DEM (discrete element method) softwares, along with 3D laser measuring equipment, have become powerful tools to describe mill charge behavior, as well as forces acting on the liners of SAG mills. With the aim of contributing to streamline this application of the advanced technologies ME Elecmetal and Universidade Federal do Rio de Janeiro, UFRJ, proposed a new approach to improve the design of mill liners using elements from mechanistic modeling of grinding. The paper presents a methodology for continuous improvement of liner design, which uses information from the DEM collision energy spectra in the mill discriminated for the different components (ore and steel balls), as well as information on the breakage properties of the ore being ground. From these it proposes the concept of "effective collisions", which corresponds to the collisions that are of sufficient magnitude to cause breakage, thus allowing to discriminate from impacts that do not cause breakage either in a first impact or after repeated loading. It also tracks the collision of steel balls against the shell in order to assess their potential damage to the liners. An industrial case study is presented of a 38’ diameter SAG mill, which was experiencing challenges associated to liner breakage and low efficiency with the old liner design. Through a modification of the liner design, simulations demonstrated the potential benefit associated to reduction in ultraprojection and improvement in mill capacity. Implementation of the new design in the SAG mill was carried out, resulting in increase in daily throughput from 6 to 12%. Further, the time spent in liner change was reduced by 47% given the reduction in the numbers of parts. This operation also benefited from having no stops due to unplanned shutdowns to replace broken tiles. These demonstrate the benefit of coupling advanced computational tools to sound engineering principles in continuous improvement of liners."

Jan 1, 2014

By M. Kalicinski, M. Lyssyy

"Access to information is a key component for making improvements to any process. This is particularly true for all aspects of the iron mining and steelmaking process. The ability to make rapid control decisions can significantly influence process outcomes, including ensuring product specification, mining quality, transportation limits, upgrade factors, waste bypass and direct shipping, among many others. While traditional laboratory methods provide feedback for such processes, having access to analysis results in real-time can lead to positive reactive and predictive control decisions to be made rapidly, leading to significant improvements throughout the process. Scantech has been designing, manufacturing and supplying technological products to the minerals industry since 2002 to enable the availability of such real-time information to a mine or plant, with the benefits being enjoyed by a wide range of operators. This paper provides a summary of the available technologies used in the iron ore and steel industries, as well as providing case studies of their use in African and Australian iron ore and European steel, as well as a description of the potential benefits of a range of analysis equipment.INTRODUCTION Access to information is critical for any process, and is a fundamental component for making process control decisions. In order to yield effective processing outcomes, it is important for that information to be readily available, preferably as quickly as possible, and to be as accurate as possible. While speed and accuracy are often traded off against each other, there are numerous technologies available in a processing environment that allow for both rapid flow of information and a high level of accuracy. The use of on-belt analysis equipment has a long trusted history of use in a number of mining and processing environments and industries, providing information such as elemental composition and grade of conveyed materials, moisture content, waste proportion and energy information. Australian company Scantech has been a provider of such equipment since 1981, and has become an industry leader in both the supply and development of on-belt analysers across a range of industries."

Jan 1, 2018

By Chen Jianhua, Shen Zhenchang, Zhang Ming, Chen Feifei

"With flotation cells scale-up, the performance of flotation cells is increasingly variated for short-coming and dead zones existing. The residence time distribution which shows the movement of tracers can assess the unexpected flows such as short circuit and dead zone in a flotation cell. In this paper, the residence time distribution of pilot flotation cell is investigated with CFD simulation. Based on the theoretical model, the short-coming probability and dead zone probability are quantitative. The ideal average residence time is similar with the actual average residence time. The mixing effect of the flotation cell approaches the ideal continuous stirred tank reactor. The operating parameters such as speed and feed velocity have complicated influence on residence time distribution. The research would be helpful to understanding flow in flotation cell and improving performances of flotation cell.INTRODUCTIONFroth flotation is a method which purifies minerals according to difference of physical and chemical surface characters of different mineral particles (Shen, Z., Chen J, 2012). Flotation cell is a key equipment for froth flotation method. The flotation cell performances have great influences on flotation index.It is difficult to evaluate flotation cell how to improve flotation procedure to complexity.The main flotation cell performances are aeration volume, air dispersion, solid suspension and residence time distribution, etc (Shen, Z., Lu, S., 2008). Residence time distribution is an important fluid hydrodynamics which could reveal the flow of pulp, mixing of particles and air bubbles. In the flotation cell, the ideal average residence time of pulp could obtain easily. But the fluid differential units would be different flow paths. The residence time of the fluid differential units is variation and would be longer or less than the average residence time. The residence time distribution would reveal the mixing effect and predict the not ideal flow in the flotation cell such as shorting cutting, dead zone, etc. As we know, the shorting cutting and dead zone would be decreased the real flotation time and it is disadvantage to better flotation effect, especially for large flotation cell. It is impossible to eliminate the not ideal flow totally. It is very important to reveal and decrease the shorting cutting and dead zone probability in the flotation cell."

Jan 1, 2018

By Chenyang Zhang, Zhigang Yin, Wei Sun, Jingxiang Zou, Jianyong He, Yuehua Hu, Zhijie Xu

"In this work, a novel compound 4-Amino-5-mercapto-1,2,4-triazole was first synthesized and its selective adsorption mechanism on the surface of chalcopyrite was comprehensively investigated using UV-vis spectra, zeta potential, Fourier Transform Infrared Spectroscopy(FTIR), X-ray Photoelectron Spectrscpy Measurements(XPS), and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and first principle calculations. The experimental and computational results consistently demonstrated that AMT would chemisorb onto the chalcopyrite surface by the formation of a five-membered chelate ring. The first principle periodic calculations further indicated that AMT would prefer to adsorb onto Cu rather than Fe due to the more negative adsorption energy of AMT on Cu on the chalcopyrite (001) surface, which was further confirmed by the coordination bonding energies of AMT-Cu and AMT-Fe based on the simplified cluster models at a higher accuracy level (UB3LYP/Def2TZVP). The bench scale results indicated that the selective index improved significantly when using AMT as a potential chalcopyrite depressant in Cu-Mo flotation separation.INTRODUCTIONFroth flotation is one of the most important processes to separate valuable minerals from gangue by taking advantage of differences in the physical chemistry of their surface properties(Laitinen et al., 2014), particularly in their surface hydrophobicity. Hydrophobicity differences between valuable and gangue minerals could be regulated by adding different chemical additives (surfactants)(Kor, Korczyk, Addai-Mensah, Krasowska, & Beattie, 2014), such as collector and depressant. It could be conducted economically to selectively separate and enrich the complicated and/or poor ores, by adopting appropriate surfactants. For example, the beneficiation of molybdenite usually relies on a two-stage process to realize flotation separation of molybdenite from other unwanted sulphide ores(Wie & Fuerstenau, 1974). In the first step, a bulk molybdenite concentrate is produced by utilizing kerosene/ diesel oil and pine oil/alcohols as collector and frother, respectively. Second, sodium hydrosulphide, sodium cyanide, ammonium sulphide, or Nokes reagent are adopted as depressants in the separation stage. However, these depressants are usually toxicant and cannot meet the requirements of environmental protection. A large number of efforts have been taken to develop alternative environmentally-friendly depressants (Ansari & Pawlik, 2007; J. H. Chen, Lan, & Liao, 2013; Li et al., 2015; Yin, Sun, Hu, Zhai, & Guan, 2017; Yin, Sun, Hu, Zhang, Guan, Liu, et al., 2017; Yin et al., 2016). Although some novel and environmental-friendly depressants have been reported to achieve good performance in Cu-Mo flotation separation at a laboratory scale, there are still some challenging problems, including toxicity, high price or poor performance in practice, which severely limit their practical applications in Cu-Mo flotation separation on a commercial scale."

Jan 1, 2018

By Aubrey Mainza, Malcolm S. Powell

"A hydrocyclone with two vortex finders, named the three-product cyclone, has been successfully tested in the Platinum industry for dealing with the dense chromite found in UG2 ores. This dense component preferentially reports to the cyclone underflow, resulting in an over-ground fine chromite component in the final product. The dense media effect caused by a high chromite concentration in the cyclone feed produces a coarsening of the cyclone overflow, which results in loss of recovery through over-size material in the float feed. The fine barren particles of chromite that report to the overflow are recovered through entrainment in the flotation process, resulting in detrimental contamination of the slag produced from the concentrate.With the three-product cyclone a middlings product has been extracted that has a higher concentration of fine chromite. This volumetric stream flow represents a small percentage of the total cyclone feed and it is thus possible to treat it separately via fine screening to remove the fine chromite from the system and recover coarse silica."

Jan 1, 2003

By Homero Delboni, Mauricio Guimarães Bergerman

"At the regrind or secondary grinding stages of metal ores, usually the concern about the energy efficiency is extremely important. In general, the specific energy consumption at this stage is higher than in the primary stages of grinding. In addition, it has been observed a tendency of finer grinding in the new projects of metallic ores, due to the finer mineral liberation, which leads to an increasing capital and operational costs. In Brazil, during the last 10 years, regrind P80 sizes of approximately 40 to 20 ?m have been necessary in all new iron and copper plants. The use of conventional ball mills, adequate for primary grinding, can result in low energy efficiency with products below a P80 of 50 ?m. This paper presents an overview of the regrind circuits in Brazil that operate with vertical mills and the results of industrial surveys at selected vertical mill circuits. Where possible, comparison is made between the plant results and the design criteria and laboratory regrind tests used for the mill sizing."

Jan 1, 2014

By F. K. Ikumapayi

An approach to environmental sustainability and improved process economy, in sulphide minerals production is recycling of process water in flotation of complex sulphide ores, although the chemistry of process water may be a critical issue to flotation efficiency. The influence of major components of calcium and sulphate ions in process water on xanthate collector adsorption and flotation response using pure chalcopyrite, galena and sphalerite minerals were investigated by Hallimond flotation, zeta-potential measurement, FTIR and XPS spectroscopy studies, while bench scale flotation tests were also carried out using complex sulphide ores. The impact of the species in flotation was comprehended using deionised water, tap water, process water and simulated water containing equivalent amount of calcium and sulphate species in process water. Hallimond flotation results showed a decrease of chalcopyrite and galena recovery in process water and also in the presence of calcium and sulphate ions in both deionised and process waters, whereas sphalerite does not respond to flotation. The adsorption of calcium and metal ions but not sulphate ions on the minerals is evidenced by zeta-potential data. FTIR and XPS studies revealed the presence of surface oxidized sulfoxy species and surface calcium carbonates on chalcopyrite in the presence of process water and water containing calcium ions, surface oxidized sulfoxy and carbonate species on galena in the presence of deionised water, process water and water containing calcium and sulphate ions, all at flotation pH 10.5, and these surface species influenced xanthate adsorption. The presence of surface oxidized sulfoxy and carbonate species at the sphalerite flotation pH 11.5 were seen in the presence of deionised water, process water and water containing calcium and sulphate ions, but the surface species does not influence xanthate adsorption. Bench scale flotation using two different complex sulphide ores showed that chalcopyrite, galena and sphalerite recoveries are better in process water than tap water. The studies showed that the process water can be recycled in flotation with no detrimental effect on grade and recovery of sulphide minerals. Keywords: sulphide minerals, flotation, zeta-potential, FTIR, XPS

Sep 1, 2012

By Richard A. Williams

The mineral processing community have been amongst the pioneer developers and early adopters of key platform technologies in analytical methods, chemistry, physical separation and advanced modelling. Fundamental research will continue to have a significant impact driven by the continued development of sustainable practices. Major drivers and challenges for change in our industry in the next two decades include: reduction in energy uses in processing; discovery of new energy materials; adoption of green chemistry routes; safeguarding of water resources; and demonstration of adherence to best practice at all times. With increasingly global mining enterprises, the provision of internationally accepted benchmarks for performance will continue to drive the creative process. This lecture highlights major opportunities around a new paradigm of Multi-scale Measurement coupled with Multi-scale Modelling, based on advanced sensors, communications and computing. Connecting real-time measurement sensors with dynamic simulation models opens up new horizons for visualising the process behaviour from an experimental and theoretical basis. Examples are given of the potential of this methodology and its implications for better design.

Jan 1, 2003

By G. Belardi

This paper presents the preliminary results of a research programme conducted to assess the feasibility of a flotation technique in the remediation of soils severely affected by heavy metal contamination. The use of flotation in soil remediation is a recent practice. The main difficulties are given by the variety and peculiarity of the heavy metal containing species, and also by the grain size. Most of the studies reported in the literature concern the use of conventional collectors, such as xanthates, after a preliminary chemical modification of the metal bearing species through sulphidization. On the basis of the minera-petrographic characterization and of speciation, some classes of reagents have been selected, capable of acting both on metal-bearing species and all metallic cations to be separated. The design of the synthetic molecules has been based on the coordinative properties of the metallic centres and functionalized in order to act as collectors for a wide range of metals independently on their surrounding atoms. In laboratory experiments a sample of stream sediment has been utilized, whose contamination is caused by the runoff from Sardinia mine waste dumps and overflow from the settling ponds. The material showed contamination mainly from Zn, Pb and Cu and to a lesser extent from Cr, Ni, Cd, and Sb associated in mixed particles of Fe and Mn. Flotation tests on a laboratory scale have been performed on grain sizes less than 355 µm in laboratory cell Minerais & Metaux. The effects of the structure of collectors (functional group, chain configuration) as well as of the principal flotation parameters (such as pH, concentration of reagent) on the grade and recovery of heavy metals in the concentrate and in the tailings (remediated soil) have been investigated. The results of the laboratory tests substantially confirm the theoretical premises, and the most effecive reagents found belong to the classes ATP, MBT, MBO, fat acids and phosphates.

Jan 1, 2014

By M. Muravyov, T. Kondrat’eva, A. Bulaev

Metallurgical treatments of sulfide ores containing copper and zinc are characterized by significant losses of base metals, particularly formation of the flotation tailings and slags during the dressing and pyrometallurgical treatment respectively. In addition, SO2 gas obtained during roasting and converting may be as raw material for sulfuric acid production. A treatment of the industrial metallurgical wastes has been investigated. Two samples of old pyrite tailings from two concentrators that contained 0.36% and 0.26% of copper and 0.23% and 0.22% of zinc were leached with 10% sulfuric acid in the column. Recovery of copper reached 47% and 38% while recovery of zinc was 47% and 41% from the first and second samples, respectively. The pregnant leach solutions contained 15.9 g/l and 10.5 g/l of ferric iron. Ferric iron is the strong oxidant and ferric containing pregnant leach solutions can be used for ferric leaching of different types of raw materials containing sulfide minerals. Therefore, ferric leaching of copper converter slag flotation tailings contained 0.53% of copper and 2.77% of zinc with the first pregnant leach solution was conducted. The effect of various experimental parameters on the leaching dynamics of copper, zinc, and iron under batch conditions was investigated. Under the best conditions (temperature 70oC, pulp density 30%) the recovery of copper and zinc reached 80% and 42%, respectively. Thus, it has been shown that acid leaching of base metals from old pyrite flotation tailings with using of the pregnant leach solution for the ferric leaching of copper converter slag flotation tailings is a prospective technique for the complex treatment of mining and metallurgical wastes. Investigated processes could be introduced into the technological flow-sheet of typical pyrometallurgical plants.

Jan 1, 2014

By J. Zou

With the increasing applications of the Chinese metal magnetic liners, the requirement for their technical specifications has become stricter and stricter. It is necessary to deeply analyse the metal magnetic liners in order to improve their reliability and economics. The key issue of metal magnetic liners is magnetic forces: their attractions to mill shell and protection layer. Mathematical models were developed using finite-element analysis software and systematic simulation analyses of the two most critical indexes of magnetic liners were performed to find out the most important parameters and their effect on the liner?s characteristics. The relationships between magnetic forces and installation gaps, thickness of permanent magnets and thickness of protection layer may be used to guide the design of metal magnetic liners for ball mills in order to achieve good economic indexes.

Jan 1, 2014

By Majid Saghaeian, Rasool Hejazi, Parisa Ghobadi

"Pulp handling in mineral processing circuits is very complicated due to its inherent different specifications compared with other fluids such as water. Because any variation in ore property (e.g. size and abrasion index) and pulp specification (e.g. density, solid content and pressure) causes problem in this part and reduces the plant availability and throughput as a result. The most common issues in the hose system are sumps and pipe-line blockage, wearing of the pumps impeller and liner, and pipe tearing specially at elbows and bends. High pressure grinding roll (HPGR) is employed in a closed circuit with a screen as the first stage of grinding in Zarand Iranian Steel Complex (ZISCO). Wearing of the pump and pipeline transferring the screen undersize stream was the main problem from the plant commissioning. The plant couldn't achieve to the design capacity because of this defect. Although various practical solutions such as improving the pipes and impeller material quality and eliminating the elbows, as much as possible, were done in order to downtime minimizing, but damages didn’t vanish. Since HPGR discharge contains somewhat rough and abrasive particles, the mentioned modifications didn't effective very much. Therefore, converting of the wet screen to dry and using of belt conveyor to the screen undersize handling was employed based on the plant capability evaluation and experimental and pilot trial results. Although this reformation imposed another additional cost (for conveyor system), but it had significant advantages such as increasing the plant availability up to 96%, reducing the operating costs of the wear parts, providing more stable operating condition for the HPGR performance and decreasing abrasion rate of the HPGR rolls liner because of the lower moist feed."

Jan 1, 2014

By Glasswell K. Nkonde, Fredrick Chileshe, Steven Simukanga

Improving food security by increasing crop output is a primary objective for most countries in the sub- Saharan region. Most soils in the region are deficient in phosphorus an important nutrient after nitrogen in plant growth. Phosphates are therefore used together with nitrogen and potassium based fertilizers in improving crop production. Zambia like many other countries in the sub-Saharan region imports phosphate fertilizers for use by its farmers. However, indigenous phosphate deposits of igneous origin exist in Zambia of which the main ones are Chilembwe in Petauke district, Mumbwa sugarloaf in Mumbwa district, and Nkombwa Hill in Isoka district. If commercially exploited, these deposits could become a ready source of inexpensive phosphate for the local farming communities in the country. Previous research has shown that partially acidulated phosphate rock (PAPR) produced using Chilembwe phosphate rock is just as agronomically effective as the imported superphosphate fertilizers on food crops in most of the Zambian soils. PAPR is produced by reacting finely ground phosphate rock with only a fraction (usually 50%) of the stoichiometric quantity of the sulphuric acid required to fully convert the apatite in the rock to monocalcium phosphate thus making the process cheaper in terms of acid consumption than the poduction of single superphosphate where the apatite in the rock has to be fully converted to monocalcium phophate. The factors that affect the percentage of available P2O5 in the PAPR produced include particle size of phosphate rock, degree of acidulation, concentration of acid, process temperature profile, residence time and drying temperature. These factors were studied in a 25kg/hr PAPR pilot-plant in the School of Mines at the University of Zambia using Chilembwe phosphate rock. The PAPR pilot-plant consisted of a rotary drum granulator as the main reactor, a rotary drum dryer and a triple deck vibrating screen. Ground phosphate rock was reacted with sulphuric acid and water in the granulator to form a granular product which entered the drier. The dry product was screened into three size fractions. The 1 – 4 mm size fraction was the final product whilst the –1mm size fraction was recycled. The +4mm size fraction was sent to a crusher while the crushed PAPR was sent back to the screens.

Jan 1, 2003

By M. Ranjbar, M. Khosravi Rad, A. Tohry

"The filling degree is defined as the volume ratio of the load inside the mill, which determines the power drawn from the motor, as long as the filling degree is not more than the optimum level. As the filling degree increases beyond the optimum level, the impact energy inside the mill will decrease and as a consequent, the mill power output will also decrease. Therefore, the mill filling degree is a key parameter in evaluating the grinding circuit performance, as it determines the mill reaction to the input feed. Since this parameter has an impact on the mill capacity, measuring the mill load is vital for control and optimization of grinding process. As in Choghart Processing Plant no instrument is available to measure the AG mill filling degree, an empirical model based on the bearing-oil pressure is proposed. The AG mill filling degree was related to the differences between the average pressure of input and output bearings, the circulating load and power drawn. It was shown that a quadratic model could relate the mill filling to the above mentioned measurements. This model showed that when the power drawn and circulating load decreases the bearing-oil pressure needs to be checked. If the bearing-oil pressure increases the feed rate needs to be decreased and steel ball be charged to the mill to increase the grinding and prevent mill overloading. INTRODUCTION The feed quality (size and hardness) affects the grinding process in AG mills. Reducing the top feed size and increasing the ore hardness reduce the mill efficiency and increase the particles with critical dimensions inside the mill. These will result in increasing the mill filling degree and reducing the mill throughput and efficiency (Wills and Finch, 2015). The volume ratio of the load inside the mill is called filling degree, which determines the mill power drawn. It is believed that if more energy is mainly spent on grinding (Wills and Finch, 2015). Therefore the mill power draw is used as a mean to control the mill efficiency."

Jan 1, 2018

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 In-Kuk Bae, Kwang-suk You, Joobeom Seo, Kwanghyun Bea, Hyung-Seok Kim

Arsenic in base metal sulfide ores is highly penalized owing to high costs for its control in metallurgical processing. The arsenic element in the lead-zinc ore, which is target ore in this study, has been shown to be in the form of arsenopyrite. Experimental work in this study is about arsenic rejection flotation, using depressant suitable for the removal of arsenopyrite from the Pb concentrate. The arsenic rejection flotation also included the oxidation treatment of Pb concentrate with H2O2. In this study, the Pb concentrates containing 80.7% Pb and 0.25% as was obtained with the additions of aluminosulfate as arsenic depressant. And through IR measurement, it was also known that the addition of aluminosulfate during arsenic rejection flotation formed calcium aluminosulfate hydrates on the surface of arsenopyrite particle, resulting in rendering arsenopyrite hydrophilic.

Jan 1, 2014

By Francisco Vicuña, Miguel Becerra, Nelson Iglesias

"The following article presents the development of a dynamic tool for the estimation of Jb/Jc rate (ball filling level / total load filling level) of a SAG mil operating in a single stage mode. Using the methodology detailed in this article, it is now possible to have a dynamic estimation tool in the operation, which enables strategic decision making and achieving a continuous development in process optimization. The estimating of the load filling level (Jc) was conducted using a power model, which in this case corresponds to the C-Model developed by (Morrell, 1993) that was calibrated by measuring the load filling levels (Jc) and balls (Jb) using the FARO laser scanning technology by means of Grind-Out and Crash-Stop procedures during the year 2013 and 2014. Finally, to estimate the dynamic filling level of full charge, Jc, three independent models were developed that allowed to feed the adjusted power model: •,SAG mill discharge grate slot wear model •,SAG mill internal volume wear model •,Ball filling level estimation model."

Jan 1, 2014

By F. Karakas

Water based paint formulations consist of some industrial minerals with quantities varying from 20 to 50 %. Quality of paint is directly related to these minerals used as pigment or filler in the production. Titanium dioxide is the most important and expensive pigment in paint formulations. Other minerals such as calcite and calcined kaolin are used as filler and mainly as a substitute for TiO2. Consequently, particle-particle interactions including adsorption, coating and size distribution of pigment mixture directly affects the paint quality. In the present paper, a new type of pigment mixture for possible use in architectural water based paints was developed through grinding. The effect of different types of grinding methods on physical properties of TiO2 and calcite mixture and the quality of paint produced by these mixtures have been revealed. Three different types of mills; conventional ball mill, vibratory ball mill and high-speed attritor were used for grinding of TiO2 and calcite. Viscosity, zeta potential and particle size distributions were used to characterize the pigment mixtures obtained upon grinding. The quality of paint was evaluated by standards based on both wet and dry paints such as viscosity, density, opacity and gloss. The paint produced with the pigment mixtures prepared in vibratory ball mill and high speed attritor showed improvement in physical properties particularly in the distribution and dispersion of mineral particles. Keywords: grinding, pigment, paint, TiO2, calcite

Sep 1, 2012