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By P. Braga, A. Chaves, S. França, A. Luz

"In Brazil, there are no official reserves of molybdenum, and the unofficial reserves are modest. Therefore, the molybdenum ore (molybdenite) produced as a co-product or by-product of emerald mining in the region of Campo Formoso, BA, has arisen as the only economic option. The flotation process is commonly used in Brazil for the recovery of molybdenite from emerald mining tailings, but it produces low-content molybdenite concentrates, thereby resulting in a product with low economic value. The molybdenite concentrate produced in Campo Formoso contains 83.5% MoS2 (50% Mo), which is less than the international standard product that contains > 90% MoS2 (54% Mo).This low value is due to the presence of talc, which is a naturally hydrophobic mineral that is also floated with the molybdenite during the flotation process. Separability studies were done in a Partridge-Smith cell using dextrin and quebracho as a molybdenite depressor in solution at different concentrations and pH values to produce a technical-grade concentrate (i.e., 90% MoS2). These basic studies were accompanied by measurements of the zeta potential and contact angle, which was determined by the capillary rise method. The results of these floatability studies were used in bench flotation tests, which were performed in a Denver laboratory flotation cell. A molybdenite concentrate of 93.4% MoS2 was obtained when dextrin was used at a concentration of 100 g/t."

Jan 1, 2014

By Song Z. Guo

Calcite and magnesite are both carbonate minerals and their crystals belong to trigonal system. Flotation tests were carried out to investigate the flotation behaviors of calcite and magnesite. The test results show that the floatability of calcite and magnesite under different grinding environment had obvious differences. The floatability of calcite using sodium oleate as collector after dry grinding is better than wet grinding, but the floatability of magnesite after wet grinding is better than dry grinding. The XPS surface elements test and zeta potential measurement show that, wet and dry grinding process makes the distribution difference of surface anion and metal cation, then influence the floatability of the two carbonate minerals using sodium oleate as collector. Difference of the carbonate crystal structure and solubility properties was also investigated. Research shows that crystal structure difference of calcite and magnesite causes the difference of solubility, which can influence the flotation behaviors under different grinding environment. Keywords: carbonate mineral, crystal structure, solubility properties, flotation, surface character

Sep 1, 2012

By Yimin Zhu

This paper introduces the sixteen mappings and rules of mineral flotation and the subgroup, period etc in periodic table of chemical element to provide mineral flotation workers to refer in theory and practice research. the nine mappings and rules of mineral flotation and the subgroup, period are Saline minerals including the first main groups and collectors of aliphatic acid and aliphatic amines, Minerals including the second main group elements and collector of aliphatic acid, Hydrated ion of the second main group elements and quartz flotation, The floatability of oxidized minerals including the four main group elements, Organic acid including the fifth main group elements and wolframe, tin flotation collectors, The floatability of sulfide minerals including the fifth main group elements, Inorganic compounds including the seventh main group elements and mineral flotation regulator, Oxidized minerals including the forth Subgroup elements and organic flotation agents with phosphorus and arsenic, Oxidized minerals including the fifth subgroup elements and organic floating agents including the fifth main group elements, Minerals including the first subgroup elements and CN-, Sulfide minerals including the second subgroup elements and CN-, The effect of the highest N-valency inorganic acids or salts including p area elements of the third period in mineral flotation, Oxidized minerals including transition elements of the forth period and 3# flocculating agent, The floatability of minerals including elements of the sixth period, Element area of generating compositions and the collecting theory of mineral flotation and so and. Keywords: mineral flotation, periodic table of chemical element, subgroup, period, regulator, coordination chemistry

Sep 1, 2012

By H. R. Manouchehri

"In mining and minerals industry, except profitability, there are some crucial factors that represent components in economic machinery of a mine and related activities. These are sustainability and minimizing environmental impact factor. Environmental concerns combined with the water and energy availability and related costs, as well as public license to operate all contrive to demand for more efforts targeting sustainability. Mining industry is highly energy-intensive (estimated to consume 6-7% of total world’s energy), with varying the energy efficiency across the industry resulting in significant costs. Size reduction is the main energy consumer contributing to almost 50% of the total energy used in mining. That means efforts must be made to introduce energy efficient comminution flow-sheets and machineries for sustainable development. Since the crushers are more energy efficient than mills, it is logic to push down-sizing in crushing stage(s) as far as technically possible. That has been strategy for Sandvik Mining and Rock Technology in supplying advanced and effective crushers to provide fine crushed product for subsequent milling stage. Lowering the energy consumption and related costs as well as increasing throughput have been the main objectives in design and development of comminution circuits and related machineries. Inefficiency in comminution technology, particularly in grinding, has long been regarded as a major area for investigation and development, especially when production of fines and ultra-fines are considered. In an attempt to explore the potential of fine crushing and its effects on subsequent milling process the fine crushing performance of Sandvik’s conventional cone crusher and Vertical Shaft Impactor (VSI) in pilot scale to define the energy consumption and circulating load in fine crushing. Tests were conducted to obtain fine crushed products at P = 2 mm in a close circuit. Furthermore, the crushed products were characterized and compared by grind-ability, morphology, and surface area measurement tests. Finally, the energy consumption to grind the crushed products to specific grind size was calculated."

Jan 1, 2018

By V. E. Vigdergauz

Possibilities of the analysis of potential energy of bubble-particle interaction on the basis of extended DLVO theory are discussed. Interaction energies of mineral silica, coal and pyrite particles with contact angles from 20 to 100 degrees and air bubbles in neutral and alkaline solutions are analyzed. It is shown that for hydrophilic silica, the formation of particle-bubble complexes (either in the area of primary or secondary potential minima) is impossible due to the high potential barriers (from 6000 to 140000 kT)and low values of the attraction force. There is shown that for coal and pyrite particles the energy of interaction vs. particle-bubble distance strongly depends on pH value. Improvement of floatability of minerals by the hydrophobization of their surface by collectors leads to the eliminating of potential barriers and the formation of the stable complexes of minerals and air bubbles in the area of primary potential minimum. In addition, due to hydrophobization of coal and pyrite changing pH has practically no influence on the energy of interaction. There are discussed results of the numerical calculations of normalized interaction forces in particle-bubble systems on the nanometer distances for pyrite, sphalerite, and chalcopyrite at contact angles up to 85° in comparison with the experimental data. The values of adhesion force for hydrophobized particles of coal and pyrite to air bubbles are about 10-5 N, that indicates stability of the formed flotation complexes. Examples of using the long-range and high-energy effect of hydrophobic interactions for improving minerals floatability are discussed. There are illustrated minerals wettability changes induced by the adsorption of thiol collector and hydrophobic polymer. Possibilities of flocculation and flotation of mineral slimes due the polymer-collector hydrophobic interactions are shown. Keywords: bubble-particle interaction, contact angle, extended DLVO theory, floatability

Sep 1, 2012

By J. B. Rubinstein

"The paper gives an overview of the history of flotation machine development. The laws of their evolution are stated and the place and role of column flotation are demonstrated.The major parameters of column cell diameter and height are discussed. Options are proposed for optimization of the hydrodynamic characteristics of large-capacity column cells. The high efficiency of columns with cell height of 4-6 m is demonstrated. The optimum parameters of multisectional column machines are determined. Their advantages compared to monocells are shown. A scaling-up procedure for column machines was developed based on flotation macro- and microhydrodynamics simulation."

Jan 1, 2003

By Xiaoxu Sun, Jianchao Yao, Jiancheng He, Shijie Lu, Hongxi Zhou

"The ball mill performance relies on impact grinding, but it has disadvantage of the lower efficiency when the ore is finer; while tower mill relies on friction shear affection with high energy efficiency, which is considered to be one of the most potential fine grinding equipment all over the world. Generated by the agitator device, the internal media movement is complex because of comprehensive interaction of screw mechanism, cylinder structure and adjacent media, which is the key factor of grinding process. But the kinematics parameter ,such as speed, acceleration, stress and so on, of media motion cannot be obtained through traditional laboratory test method, which restricts deeply research on finer grinding mechanism seriously. In order to solve this problem, characteristics of media motion in tower mill is studied via the discrete element method. Coefficient of restitution, coefficient of static friction and coefficient of rolling friction are the key parameters affecting the media movement, which were calibrated by stacking angle test firstly. A 3kW tower mill is established as the model for simulation. At last one appropriate simulation strategy is selected to increase simulation accuracy. The characteristic of media motion is obtained based on the computer simulation analysis: macroscopically, the media in tower mill is a dynamic equilibrium state generally accompanied by spiral up and down movement all the time. And it has been found that the maximum lifting height is proportional to the rotation speed of agitator shaft. The velocity of media at the edge of screw stirrer is biggest, while the velocity of media near the cylinder wall is smaller, so the grinding performance between the two ring areas is the best. The rotational speed of agitator shaft and media filling ratio are the two most important operating parameters in tower mill. The impact curve of two main operating parameters on the grinding intensity and energy efficiency are obtained. All these can provide theoretical basis and technical support for operating parameters setting of industrial tower mill."

Jan 1, 2018

By P. Saha, D. M. Chakrabarti, National Metallurgical Laboratory, P. Bhattacharyya, B. R. Sarkhel

The estimated reserve of the phosphatic soils at the Sukulu hills region of Uganda upto a depth of 60 meters is of the order of 200 million tonnes and analyses 10-12% P2O5. A 5-tonne sample of the phosphatic soil was received at the National Metallurgical Laboratory (NML), India for beneficiation studies. The ore occurred as a naturally degraded soil deposit and the slime contained earthy lateritic minerals which made it extremely sticky. Microscopic examination revealed the presence of limonite, magnetite (martitised), hematite and goethite as major minerals along with apatite and quartz. Presence of clay was indicated by earthy smell on moistening the sample. It was observed that getting rid of the slime was as important for adequate beneficiation of the ore, as it was difficult. Earlier studies on samples of the same ore at the NML and abroad established that it was necessary to pass the ore through a series of three stages of desliming, each consisting of a step of rigorous attrition scrubbing followed by hydrocycloning, for effective elimination of the sticky slimy coating which stubbornly adhered to mineral grains. Studies were carried out at the NML in two phases to develop a flowsheet for beneficiation of the phosphatic soil. In the first phase, reproducibility of the results obtained by employing a flowsheet developed abroad was confirmed along with suggesting some modifications of the flowsheet. Then 200 kg. of concentrate was produced following the recommended flowsheet for evaluation of its suitability for production of fertilisers. To remove the limonitic slimy coating, which stubbornly adheres to the other mineral grains, it was necessary to subject the ROM ore, after screening out the +840 micron size fraction which contained only 1.75% P2O5 , to three stages of hydrocycloning each preceded by attrition scrubbing. Then only conventional beneficiation techniques could be effectively employed to upgrade the ore.

Jan 1, 2003

By P. Somasundaran

Treatment of mineral surfaces with appropriate surfactants plays an important role in mineral processing operations such as flotation, flocculation and dewatering. Recently biosurfactants, in particular, have received a considerable amount of attention because of their unique surface active properties and biodegradability. In this work we examined the performance of biosurfactants, sugar based alkyl glycosides and sophorolipid esters as reagents to control the hydrophobicity of minerals with selectivity of adsorption on mineral surfaces for flotation applications. It was discovered that n-dodecyl-ß-D-maltoside adsorbs on alumina, titania and hematite but, interestingly, not on silica. The hydrophobicity obtained is governed both by the surface coverage as well as the nanostructure of the adsorbed layer in terms of orientation of the adsorbed species. Surprisingly, even though the above surfactants are non-ionic, their adsorption was pH-dependent. We have correlated this pH dependence to the type of species on the mineral surface. Also it is shown that mixing of these surfactants with traditional ones can help reduce the carbon footprint due to synergy between the reagents and help selectivity due to antagonism. The experimental results were analyzed to get information on optimal pH and dosage conditions, for mineral surface modification. The study provides guidance for mineral treatments using biosurfactants and the potential use of these next generation reagents in mineral processing.

Jan 1, 2014

By Per Svedensten

One of the most significant behaviour of a crushing plant is the constant variation in the process. The variation is caused by two major effects. The first and constantly changing is the rock material properties. During operation rock material with different strength and particle size distribution is fed to the plant which makes the performance of the equipment to vary. The second and more slowly changing variation is caused by wear on the processing equipment. These effects must be predicted in order to be able to optimise a crushing plant. This paper demonstrates how Monte Carlo simulation can be utilised to study and operate crush-ing plants. By introducing Monte Carlo simulation the varying process can be study and also optimised. To maintain the optimised process performance supervision is needed. This paper demonstrates how results from the Monte Carlo simulation can be utilised for process supervision. Charts for process measurements can for example be derived. These can then be used to guide decision making and understand how the variation and performance of the plant changes over time.

Jan 1, 2014

By Yongfu Yu, Xiaotie Wang, Fuguang Zhang, Liping Che

"The flotation process of native Rare Earth minerals such as bastnasite, monazite, mixed minerals of bastnasite and monazite, using the new effective collector Dh was studied in this paper, respectively, and the flotation properties are described. The good qualities of the new collector Dh were revealed through comparing with other collector of Rare Earth minerals. The test results of different ore samples show that at moderate pulp pH (8.5-9.5), Rare earth minerals can be effectively separated from barium, calcium and silicon bearing intergrowth minerals (barite, calcite and silicate minerals) and high quality Rare Earth concentrates can be obtained successfully by the new collector Dh, acid silica gel, turpentine and reagents fitting together rationally. In order to determine optimum technical conditions, the effect of pulp pH, pulp temperature, pulp density and the effect of dosage of reagents (Dh and acid silica gel) on the flotation were investigated in the test.Simultaneously, the paper explores the mechanism of the flotation of Rare Earth minerals from intergrowth minerals. The infrared spectra for Dh and Rare Earth cation by analysis in theory shows that Dh formed chelate complex with Rare Earth cation and were adsorbed on the surfaces of Rare Earth minerals. The mechanism of the intergrowth minerals depressed by acid silica gel can be explained as gummy colloid hydrolyzed from acid silica gel which are selectively absorbed on the gangue minerals, making them hydrophilic and depressed, with pulp pH value of alkalescent."

Jan 1, 2003

By M. L. Liu

This work reports the results about the determination of mean activity coefficients and relative partial molar free energies for copper sulfide mineral bioleaching solutions by potentiometric method at 25ºC. The experimental potentiometric data were obtained by combining a solid state membrane-cupric ion selective electrode (Cu2+ ISE), containing a KNO3 filling solution, and an Ag/AgCl electrode. The measurements were performed in different series of copper sulfide mineral bioleaching solutions. The non-ideal behavior of the system was described on the base of the Pitzer ion-interaction model for mixed salts. Meanwhile, the relative partial molar free energies of bioleaching solution were investigated. The determination of the thermodynamic properties offers a basic data for the study of copper sulfide mineral bioleaching solutions.

Jan 1, 2014

By J. P. Dai

The Fankou Mine in Guangdong province, China, processes a polymetallic ore containing averagely 4.2% Pb, 8.5% Zn, and 90 g/t Ag. The main metal minerals including sphalerite, galena and pyrite are very finely disseminated and unevenly occurred in the ore, making it difficult to liberate them from each other. This paper presents the processing technology of the Fankou plant and the characteristic features of the novel technology applied.

Jan 1, 2014

By V. Hudecek

Problems of sudden outbursts of rock and gas present in deep mine mining ones of the most complicated interrogation. It is searching for the methods of prediction and prognosis that can be most useful for the government of these phenomena. Till now the pressure and the desorption of gas in bore holes was consider to be the decisive criteria. By the work of authors with using of statistical date was verify that for considerable reliability of forecast and prevent outbursts is necessity investigate characteristics of workplace and other indicators. These indicators were analyzing and assemblage into mathematical dependences which represent active and passive force asserting with in the process of rush. It was validated by using the equations which are presented in the manuscript that the accuracy of pre-diction of the phenomena is higher and methods of preventions are better also.

Jan 1, 2014

By U. S. Chattopadhyay

The estimated requirement of the nation by the year 2020 is approx. 80 Mt of steel and more than 0.2 million MW installed capacity of the electricity, thereby increasing the consumption of the coking and non-coking coal, which is expected to be in tune of about 75 Mt & 500 Mt respectively. One of the major deleterious factors in achieving the goal is the deteriorating quality of the feed coal used in both steel and power industries. Indian coking coals, in general, are typified by high ash, high inert (both organic and inorganic), low rank, low reactive macerals content, heterogeneous petrographic make-up, inferior coking properties and poor amenability to washing, thereby necessitating suitable washing measure. Coke-based steel industries in India require washed coking coal containing ash % varying between 17-19. The situation demands taking on immediate challenges to fill up the gap between the requirements and supply of coking coal. This paper reviews the R&D attempts in this laboratory and throws light on the key measures as long-term solution to the problem. Search for alternative source of coking coal, like LVC coal and their judicious preparation technology. The low volatile coking coal (LVCC) constitutes about 50% of the total coking coal reserves in India. These coals are characterized by high raw coal ash content (37 to 40%) and very difficult washability potential. If these coals are treated in the existing washeries, which are generally 2 or 3-product systems, the cost of clean coal is high as the byproduct sale value is low. It has been proposed to produce a new type of by product, which enjoys high demand and good coking properties.

Sep 1, 2012

By Rakesh Kumar, S. Mehrotra, T. Alex

"This paper, an overview of our recent findings on mechanical activation (MA) of minerals/materials, emphasizes the importance of sample genesis, mechanically induced/altered porosity and surface area, mineral interactions, glassy inorganic materials, surface alteration and zeta potential changes and, mechanically induced reactivity of solids. Materials investigated include Al-oxyhydroxides (gibbsite and boehmite), fly ash and granulated blast furnace slag. Planetary, attrition, vibratory and conventional ball mills are used for MA. Genesis of boehmite has been found to have a bearing on its behavior during MA. For example, BET specific surface area (SSA) of boehmite prepared by thermal dehydroxylation of gibbsite has decreased from 265 to 65 m2/g during 240 min of MA; in contrast, the SSA of hydrothermal boehmite has increased from ~2 to 36 m2/g. Mechanisms of surface area changes in the two boehmite samples differing in their genesis is explored. MA of gibbsite and its mixture with hematite/quartz using attrition milling has indicated that the presence of the second phase promotes amorphisation. Amorphous materials show signs of change in nature of bonding during milling as illustrated by MA of fly ash. Physicochemical changes during MA are not restricted to the bulk phase. The genesis of zeta potential changes in MA solids can be many; for example texture induced zeta potential changes as observed for gibbsite, while zeta potential changes during the milling of granulated blast furnace slag occur due to enhanced (possibly non-congruent) dissolution. Interesting manifestations of mechanically induced reactivity and its correlation with physicochemical changes are illustrated in terms of alkali leaching of boehmite and, hydration of MA slag. New findings reported here are associated with several open questions and are highlighted in the paper."

Jan 1, 2014

By Peter Ay, Florian Logsch, Satyanarayana Narra

"The traditional lignin separation process from the precipitated suspension creates severe filtration problems by plugging of the filter medium due to the small particle size (20 to 60 µm) of the suspended lignins. The plugging causes further problems in the successive processing of the filter cake. A new lignin separation process has been developed at the Brandenburg University of Technology (BTU) Cottbus as a part of the Research and Development and Demonstration (R & D & D) project "LignoBioFuel". The new developed process separates lignin in the form of granules with diameters ranging from 100 µm to 300 µm. The restrainment of the granule’s size in their successive treatments is expected to result in higher filtration efficiencies and reduction in plugging of filter mediums. To evaluate the filtration efficiency, the filtration resistance of the produced granules as well as the conventional suspensions has been investigated. The results show that there is a 60 to 80 % filtration efficiency increase and around 60 % reduction in plugging of filter mediums with the lignin granules in comparison to the conventional suspensions. Furthermore the successive processing of lignin granules was easier due to their porous structures removing the impurities such as adherent acids and salts. The purity of the separated lignin was measured with their sulphur (reduced from 7 % to 2.7 %) and ash (reduced from 46 % to 0.5 %) contents. The newly developed process has displayed better results in comparison to that of the conventional process. The new process displays high potentials in optimizing and improving the present state of the art treatments and is promising several ecological, economical and environmental improvements."

Jan 1, 2014

By L. Kuzev

Unknown and unpopular vibrational grinding mills possibilities to horizontal working chambers have been discussed. They can be realized under normal conditions with the typical values of vibrations applied with vibrational grinding which are: vibration frequency from 15 Hz to 50 Hz, vibration amplitude to 6 mm and vibration geometry. These possibilities constantly increase involving new raw materials and processes. Vibration grinding is possible with other technological process accompanied by intensified technological processing, while the process decreases. In many cases these technological decisions are original.

Jan 1, 2014

By József Faitli, Imre Gombköto, Barnabás Csoke, Tamás Magyar, Beáta Oláh, Sándor Nagy

"Raw materials are among the main building blocks of a growing economy. Without raw materials, no matter whether it is primary or secondary, production is not possible. Products with high added value require special materials. Recently, worldwide production of some important raw materials mainly comes from a handful of countries, for example: China (Rare Earths Elements (REE)), Russia, South Africa (Platinum Group Elements (PGE)), Democratic Republic of Congo (Cobalt), etc. In the EU as well as in Hungary, the importance of the so called 14 critical raw materials has been recognized. Within the frame of the TÁMOP-4.2.2.A-11/1/KONV-2012-0005 - CriticEL project, the Institute of Raw Materials Preparation and Environmental Processing in cooperation with the Institute of Mineralogy and Geology of the University of Miskolc are working on the exploration of the primary and secondary sources and developing innovative preparation technologies of critical raw materials in Hungary. The research work showed in this article, focused on the recovery of critical materials from LCD TVs and monitors. There are high deviations in different literatures regarding to concentrations of critical elements in displays (e.g.: indium), probably because of the differences in production year, producers and recovery technologies. During the research - described in this study - a well specified sample of quite large amount of displays had been used. The exact place and shape of the ITO (indium-tin oxide) layer were determined by SEM analysis. The applied preparation technology was developed based on the results of our investigations and by technologies found in the literature. The developed process accomplishes two main parts: the mechanical preparation (mainly the liberation of different display layers, removal of liquid crystal) and the acidic dissolution of indium."

Jan 1, 2014

By Liang Dianyin

In this paper, the molybdenite flotation tailing of cleaner-scavenger bank which has a mass of very fine particles has been taken as raw ore to be processed by flotation with/without ultrasonic. The effect of ultrasonic frequency, intensity, processing time and uploading location on molybdenite flotation efficiency is investigated by four-factor three-level orthogonal experiment, and the effect significances of these ultrasonic variables to molybdenite flotation efficiency have also been evaluated. Single-factor analysis of variance is conducted to investigate whether the effect of ultrasonic on molybdenum ore flotation efficiency is significant or not. The samples extracted from different ore species in different time have been mixed to analyze the particle size. The results show that the particle size of +38µm in concentrate obviously increases while the particle size of -25µmobviouslydecreaseswith ultrasonic, which means that ultrasonic is good for flotation due to sludge removing effect. Keywords: ultrasonic, flotation efficiency, sulfide ore, tailing, grade, sludge removing

Sep 1, 2012