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By Yuliy Rubinstein

"The paper presents a analysis of the history and the trends of development of flotation apparatus. The laws of their evolution are stated and the place and role of column flotation are indicated. It is demonstrate development and different design of column apparatus. The major parameters of column cell such as diameter and height are discussed. Options are proposed on optimization of hydrodynamic characteristics of columns with large-capacity cells. High efficiency of columns with cell height of 4-6 m is shown on examples of coal preparation. A new generation of multi sectional column cells has been developed. In the cells are zones with different aerohydrodynamic parameters: combined in the machine are co-and counter- counter flows of phases. The transition from single-chamber column to multi-sectional apparatus makes it possible to create favourable hydrodynamic and aeration regimes in each section of the column dependent on the pattern of material distribution by floatability. Efficiency of application different designs column apparatus uses shown on the example of enrichment of various non-ferrous metals ores and coal. The principles of mathematical simulation of the flotation process are developed. A scaling-up procedure for column cells was based on flotation macro- and micro- dynamics simulation.INTRODUCTIONColumn flotation is considered to be one of the most significant achievement in the field of mineral processing in the end of last century. We cannot but agree with this statement but would like to understand what underlies this success. History of the flotation column can not be considered in isolation from the development of flotation apparatus on the whole. It can be argued that the first attempt to switch from oil flotation to the use of bubbles during flotation was performed Bessel brothers in 1877 (Berlin patent 42 class 22, July 2) and in 1886 (Berlin patent 39,369 May 12). According to these patents, the crushed ore was mixed with oils , hydrocarbons and water. Then the pulp received in this way was heated up to boiling . Air bubbles and steam formed during boiling facilitate the flotation of ore particles coated with oil (first patent) or bubbles been generated by the reaction of lime with acid (second patent). The evolution in the design of the flotation apparatus incorporates the following key stages. Further development is connected with the Francis Elmore’s idea to use gas bubbles received at water electrolysis (UK, 13578; 1904). This method was not introduced then, but much later, in our time and on the essentially new technical basis it found a use for sewage treatment (electroflotation). Gas bubbling under vacuum patented also by Elmore (UK, 17816; 1904) obtained a practical use. It should be noted that the method did not lose its importance till now. The design of the camera has been surely optimized (Glembotskii etal, 1963). A year later A. Macquisten (UK, 26712) developed pressure (compression) flotation. Thus, the H.Sulman, H.Picard, D. Bell’s (US, 853120, May 29, 1905) basic patent and the adjoining T. Goover’s patent 1910 (US, 953746) formed the basis of the first and most important element of modern flotation: flotation with air bubbles sucked in from the environment. In 1914, J.Callow received a patent for on an apparatus where air was sparged through the porous false bottom of the cell ( US, 1104755). Woolen fabric folded four times was fixed on a perforated metal frame to be used for air sparging (Gaudin, 1932). The following year Durrel created the prototype of the injection (ejector) apparatus. The jet aerator made it possible to significantly reduce the size of the bubbles, in comparison with the filter cloth. An apparatus with slurry pre-aeration in an airlift prior to feeding into separation cell was developed Wagner in 1917 (US, 1235083). And finally, the first column apparatus with a counter-current of slurry and air was developed by M. Towne and S. Flynn in 1919(US, 1,295,817). ("

Jan 1, 2018

By V. V. Zakopaylo, M. V. Lukyantseva, V. A. Ignatkina, V. A. Bocharov, L. C. Khachatryan, D. M. Altynamanov, A. A. Kayumov, R. H. Sharipov

"This research was aimed to explain the reasons of low floatability of tennantite from refractory pyrite ores of non-ferrous metals and to create a reagent regime for selective increasing a recovery of copper sulfide minerals from arsenic-containing copper pyrite ore. ?opper-zinc ore of the Uzelga deposit has 89% of pyrite, some part as melnikovite; copper is assayed as 3.58% of tennantite and 0.25% of chalcopyrite; there is 2.19% sphalerite. Sulfide minerals are very finely disseminated. Tennantite is genetically related to primary copper sulfides. Graphene was identified on the surface of tennantite by a transmission electron microscopy (TEM) method. The recovery of tennantite was rose up by using the collector M-TF. M-TF is the mixture of diisobutylditiophosphate (DTF) and O-isopropyl-N-methyl (ethyl) (TC) in the certain ratio. M-TF change up a kinetic of copper sulfide flotation in a slightly alkaline medium, but pyrite has slowly floatability at this moment. A depressing effect of thiosulfate ions in a liquid phase of pulp flotation tennantite from pyrite ore has been established. A copper recovery up 14.2% (from 67.7 to 82.0%) into a copper concentrate level off copper grade of 18.65% (butkx) and 18.68% (M-TF) has been increased by the new technology with M-TF compared to a standard technology with butkx. A main copper recovery up to 50 % in an inter-cycle copper concentrate assaying 19-21% Cu in case of using M-TF was gotten. A zinc concentrate with recovery of 50% and a zinc assay of 41.76% by a standard flow sheet with butyl xanthate was obtained. A zinc recovery of 70.3% with a zinc grade of 44.17% by the M-TF technology was achieved.INTRODUCTION The pyrite copper-zinc ores of the Urals region are considered refractory. The distinctive features of these ores include a high content of pyrite (90-95%), the presence of arsenopyrite and arsenical pyrite, and the simultaneous presence of chalcopyrite, bornite, tennantite with the predominance of the latter (Andreasen et al.,2008;.Dobrotsvetov, 2009; Chanturiya et al. 2016). The flotation properties of tennantite differ from those of chalcopyrite (Xumeng Chen, Yongjun Peng, Dee Bradshaw. 2014), which is the reason why a comprehensive study was under taken of the flotation activity of tennantite and a process for its recovery was developed. The proposed agent treatment and flotation process make it possible to produce salable copper and zinc concentrates."

Jan 1, 2018

By Bianca Foggiatto, Marcos Bueno, Rajiv Chandramohan, Eddie McLean, Greg Lane

"With the increasing depletion of high-grade ore deposits, smarter mineral processing solutions are required to achieve sustainable and economic methods for mining and processing low-grade deposits. In order to make the treatment of low-grade deposits economically viable, large quantities of rock need to be mined and processed. The associated infrastructure costs (power, water supply, accommodation and support services, waste storage) result in a substantial penalty on the project, from both capital and operating cost perspectives. As a consequence, the challenge for the mining industry is to overcome the associated rise in energy and water consumption as well as increased project complexity when processing large amounts of low grade ore. Ore sorting technologies have been used for many years, predominantly on small projects, enabling the upgrade of marginal ores. Several sorting methods based on characteristics including specific gravity, radiometry, colour, particle size, grade and other detectable physical characteristics have been employed. The challenge for large low-grade ore bodies is to crush and sort at coarser rock size in order to minimise specific energy consumption in comminution and to reduce waste disposal costs. For large projects, the understanding of the economic impact of ore sorting is limited. The economic drivers include plant head grade improvement; sorting infrastructure capital, operating and maintenance costs; waste material handling and other environmental costs related to waste disposal. This paper analyses the economic impact of ore sorting in a large mineral processing operation. The focus of the analysis is to compare NPVs for a circuit including screening and ore sorting stages. A project for processing an Australian copper sulphide ore is considered as an example for this study."

Jan 1, 2014

By H. Hamza, M. R. MacIver, M. Pawlik, L. Malin

"Size and shape are important properties of aggregates formed in engineering processes and natural systems. Measurement of aggregate size or shape is a challenge when the solids concentration is beyond the gel point, ?? > ??g, when the aggregates are in contact and it is difficult to distinguish or segment individual particles in the network. This paper describes the use of a micro-computed tomography (micro-CT) method for the calculation of the aggregate volume fraction, ??, and a characteristic aggregate length, ??a, based on a 3D chord length measurement algorithm. These parameters can be used to quantify changes in aggregate and pore size during a compressive yield stress test to help understand the impact of flocculation and network structure on dewatering. INTRODUCTION In a thickener, flocculation is often used as a pre-treatment step and the final solids content of the underflow depends on the network strength and permeability of the bed formed by settled aggregates (Usher, Spehar, and Scales 2009). This paper describes the measurement and analysis of micro-computed tomography (micro-CT) of flocculated mineral sediments to obtain a characteristic length, ??a, of the aggregate and pore phases during a staged compressive yield stress experiment. This parameter may be used as an indicator of changes in aggregate and pore size to quantify material behaviour in solid-liquid separation processes that depend on self-weight compression or applied pressure. This analysis was carried out to help understand the effect of flocculation on aggregate structure and the thickening process as part of a broader research on the improved solid liquid separation of tailings produced in the oil sands industry.Aggregate properties The solids phase of an aggregated or flocculated suspension will eventually settle – if left undisturbed – under the influence of gravity. As settling of a flocculated suspension continues, the solids volume concentration, ??, may increase to the gel point or gelation threshold (Landman and White 1994), ??g, above which the aggregates form a network of touching particles, or space-filling structure (Kranenburg 1994). In the sediment bed, the aggregates are surrounded by fluid and occupy a partial volume fraction, ??, according to"

Jan 1, 2018

By B. McFadzean

Thiol collector mixtures are commonly used in the flotation of base metal sulfides and platinum-bearing ores. There are synergistic benefits claimed for these collector mixtures, with mixtures lowering total dosage requirements, improving coarse particle recovery and the rate of flotation. Some of the secondary collectors are known to have frothing effects. Therefore, a previous study aimed to decouple froth and pulp effects and considered only the bubble-particle attachments in the pulp. This was achieved through microflotation experiments, where various ratios of the ethyl and isobutyl chain lengths of xanthates, dithiocarbamates and dithiophosphates were used as collectors. Results from these experiments showed a marked increase in galena recovery using mixtures of xanthate with either dithiophosphate or dithiocarbamate. In the current study, the froth phase was introduced in the form of batch flotation studies to determine whether benefits noted during microflotation experiments would be carried through to a more realistic froth flotation scenario. The findings show that there was no significant difference in the flotation recovery between the best single collectors and mixtures of these collectors. In addition, single collectors that behaved poorly in microflotation experiments showed good flotation performance in the batch flotation experiments. The differences between the microflotation results and the batch flotation results are attributed to differences in particle froth stabilizing properties and/or differences in energy input between the microflotation and batch flotation cells. In addition, galena and pyrite showed marked differences in frothing effects and in their preferences for collector type. Keywords: froth flotation, collector mixtures, sulphide minerals

Sep 1, 2012

By Zehong Wang

Selecting sodium polyacrylate (PAAS) as grinding aid, the effect of grinding aid on the grinding efficiency of bauxite taken from Shanxi province was studied and its mechanisms were analyzed by measuring the variation of adsorption characteristic, pulp viscosity, surface electric potential of the bauxite and the surface appearance of particles. The results showed that, compared with no grinding aids added the content of -0.074mm in the ground product was increased by 5.45 percentage points under the optimal grinding conditions adding PAAS as grinding aid when the amount of PAAS was 0.7%wt of bauxite. Because the physical adsorption and chemical adsorption were occurred on the bauxite surface, which could reduce the pulp viscosity, change the surface electric potential of the bauxite, enhance the surface appearance of particles and lower the surface hardness of the bauxite, the grinding efficiency of bauxite was increased by PAAS. Keywords: bauxite, grinding aids, grinding efficiency, mechanism

Sep 1, 2012

By N. Vorob?ev-Desyatovskii

The process of gold(I) adsorption on activated carbon (AC) from aqueous Na[Au(CN)2] and the state of the adsorbed gold cyanide complex on the adsorbent surface was investigated by photometry, XPS, XANES methods. By DFT method, quantum-chemical calculations were performed of the gold cyanide species on activated carbon surface. It was established that the binding of gold(I) with the surface of carbon involved several simultaneous processes governing the selective adsorption of gold(I) from the cyanide solutions.

Sep 1, 2012

The flotation efficiency of magnetic concentrate of the Anhui hematite ore, which includes a great quantity of iron-bearing silicates, has been studied through reverse flotation test with a new type of collector Fly-102. The results indicate that collector Fly-102 has a strong adaptability to the variation of temperature, when the flotation temperature is in the range of 10? to 35?, using collector Fly-102 can obtain good flotation indexes. Collector Fly-102 has a strong adaptability to the variation of the slime contents and grades of the flotation samples. When the content of slime and the grade of the flotation feeds are 30% and 55.63% respectively, under the condition that the temperature is 15?, the open circuit flotation test was carried out with collector Fly-102. After one-stage roughing, one-stage cleaning and two-stage scavenging, a better result is got, the grade of iron concentrate reaches 67.12%, and the recovery of iron concentrate comes up to 84.15%.

Sep 1, 2012

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 Jerzy A. Mielczarski

The separation of albites from quartz by flotation applying the conventional HF-methods is no longer acceptable from an environmental and health point of view. Therefore, the search for a new reagent scheme without using HF depressor for separation of albite from quartz is under consideration. The flotation behaviour of ore mineral components depends on the produced hydrophobic or hydrophilic surface coverage (chemical functionalization). Currently we have excellent possibility of monitoring surface composition and structure at molecular and atomic levels at surfaces of natural minerals contacted with aqueous solutions of collectors, activators, depressants which is vitally important for the understanding of the surface chemistry that govern selective and efficient flotation. Detailed surface characterization of minerals before and after their exposition to different solution conditions was performed by the most modern spectroscopic techniques such as developed by us the infrared external reflection technique combined with spectral simulation and X-ray photoelectron spectroscopy (XPS). It is possible to monitor surface reactions which facilitate the separation process and those which bring disadvantage to selective flotation. At first we found that a small amount of ?mineral impurity? presented in natural ore could play important role in selective hydrophobization process. It was found that the pH of solution (parameter possible to control) and natural mineral impurities present in mineral samples (parameter related to ore origin) play a very important role in the separation process. Another important parameter is interaction between minerals, quartz and albite, present in aqueous solution. The limitation of flotation separation resulting from chemistry will be discussed. Moreover, the most promising scheme for separation of albites from quartz will be examined.

Jan 1, 2014

By J. Temuujin

Mongolia has some of the world?s largest coal reserves with an estimated total coal reserve of over 150 billion tonnes. At present, over 90% of Mongolian electricity is produced by combined heat and thermal power stations. The main coal deposits used for Central power system's power stations are Baganuur, Shivee-ovoo lignite type coal and Shariin gol bituminous coal. In Mongolia almost 600,000 tonnes of coal combustion by-products are disposed of in waste ponds. In this research, we have thoroughly characterized Mongolian coal combustion by-products including fly ashes sourced directly from thermal power stations and ash retrieved from ponds. It was determined that fly ashes generated from Baganuur and Shivee-ovoo coal deposits are class C, while ash from Shariin gol coal is class F (according the ASTM C618). All ash products were characterized by chemical, mineralogical, granulometrical, porosity, FE-SEM and radiation methods. Fly ashes sourced directly from power stations were found to be more suitable for manufacture of geopolymers for building materials application and zeolite synthesis than ashes retrieved from ash ponds. The adsorption and porous properties of zeolitic compounds were measured and found to be suitable for adsorption of Cr6+ from simulated tannery waste water. Keywords: coal, coal combustion by products, synthesis, geopolymers, zeolitic compound

Sep 1, 2012

By V. Buddhiraju

Liberation of valuable minerals from low-grade ores is an important challenge faced by the minerals industry. It is necessary to grind the ore to extremely fine size in order to liberate the mineral from such ores. As it is generally difficult to produce ultra-fine particles of diameter less than 1-10 mm using traditional grinding equipment such as the ball mill and the rod mill, several new types of grinding equipment are being explored to produce ultra-fine particles. The planetary ball mill is promising in that it makes grinding to submicron sizes possible by imparting high energy to the ground powder. It consists of four pots mounted on a disc. The pots and the disc rotate in opposite directions. The high-speed rotation of the pots and the disc makes the grinding media move at high centrifugal velocities leading to high impact energy and thus improving the grinding performance. The planetary mill is currently being explored for its capability to produce ultra-fine particles on a large scale. In this context, there is a need to understand the dynamics of the ultra-fine grinding process within the planetary ball mill. Here, we address this need by studying the movement of media inside the pots and the grinding kinetics, employing both experimental and modeling techniques. The experiments were conducted on a laboratory scale planetary ball mill. The particle size distribution of the powder was monitored to allow an estimate of the grinding kinetics to be made while video images of the media profiles inside the pots were taken to allow quantification of the media movement as a function of process variables such as the media size, percent loading, etc. The population balance modeling (PBM) framework was used to simulate the kinetics of grinding while the discrete element modeling (DEM) approach was utilized to simulate the media motion. The parameters in the population balance model, namely, the specific breakage rate and the breakage distribution function were determined by fitting the batch grinding equation to the experimental data. The predicted powder size distributions were found to be in good agreement with the experimental data. The experimental results have shown that the mean size of product powder decreases as the size of the grinding media decreases. Keywords: population balance modeling, grinding, planetary mill, grinding media, grinding equation

Sep 1, 2012

By A. E. Sobolev

The kinetics of hydrochemical oxidation of antimonite in solutions of nitric acid was studied using the rotating disk method and the factor experiment design. The dependences of the antimonite?s oxidation rate on concentration of nitric acid solutions, temperature, disk rotation frequency, and duration of interaction were determined. The adequate kinetic models allowing calculating the specific oxidation rate at any combination of the values of the influencing factors were obtained. The oxidation process is found to proceed in a mixed mode, close to chemically controlled. Gradually, as the sediments of elemental sulphur and Sb2O5 accumulate on the disk surface, the process becomes controlled by internal diffusion. The observed high (more than second) order of the oxidation rate with respect to the concentration of nitric acid was explained by the autocatalytic action of the acid reduction products. The apparent activation energy depends on the stage of interaction. At the initial stage (in a mixed mode of the process proceeding), it depends on nitric acid concentration and varies from 31.5 kJ?mol?1 (in 2 M HNO3) to 36.1 kJ?mol?1 (in 10 M HNO3). This trend indicates the weakening of diffusion limitations with a nitric acid concentration increase. When the process is controlled by internal diffusion, the apparent activation energy was found to be 14.5 kJ?mol?1. The obtained kinetic characteristics enlarge the database on hydrochemical oxidation kinetics of sulphides and can be used for the elaboration of the recommendations for the effective comprehensive exploitation of antimony-bearing ores and concentrates.

Jan 1, 2014

By J. Seo, W. Kim, I. Bae

"Microcrystalline silica impurities such as quartz and opal-CT commonly associated in bentonite should be controlled and removed as far as possible when bentonite is used as biocompatible raw material because they show sufficient evidence of carcinogenicity. Since opal-CT contained in bentonite in trace amounts cannot be well separated by conventional sedimentation method, in this work, the ultrasound-assisted removal of the impurity was attempted. Irradiating ultrasound into bentonite-water suspension promoted the production of fine montmorillonite particles in the suspension and the production markedly increased when montmorillonite was activated by Na2CO3. Subsequent centrifugation of the suspension made it possible to recover pure montmorillonite particles as an overflow product. Only 16.2 mass % of total solids was recovered as an overflow from the non-activated suspension, whereas 63.5 mass % was recovered from the activated suspension at centrifuging speed of 10000 rpm. Increasing sonicating time enhanced the yield of overflow, however, excessive sonication up to 10 min hindered the purification of montmorillonite. It was observed that the peak reflection of (101) plane of opal-CT in overflow increased as sonicating time increased during prolonged sonication. INTRODUCTION Bentonite consisting predominantly of mineral montmorillonite is clay-rich soft rock generated frequently from the alteration of volcanic ash. Depending on the nature of its genesis, bentonite contains a variety of accessory minerals, which may include mainly quartz, feldspar, opal cristobalite/tridymite (opal-CT), calcite, illite and mica. The presence of these accessory minerals can impact the industrial value of the deposit, reducing its commercial value depending on its applications. Therefore, bentonite is often purified by removing these impurity minerals for special applications where specific properties and characteristics are required (Murray, 1999). Among the special applications, bentonite is often used in the cosmetic and pharmaceutical industry as both excipient and active ingredient in the forms of liquid (suspensions, emulsions), semi-solid (creams, ointments) and solid (powder, capsules and tablets). The basic requirements for bentonite to be used as raw material are pure, microbiological and mineralogical inertness. Physical properties such as swelling volume and gel formation are also important. Particularly, microcrystalline silica polymorphs such as quartz, cristobalite and opal-CT should be controlled and removed as far as possible because they show sufficient evidence of carcinogenicity in humans."

Jan 1, 2018

By J. C. van Dyk

In a previous study by Van Dyk, et al., (2006) and Van Dyk et al. (2006), a FactSage model was developed to understand the chemistry and interpret mineral matter transformation during a fixed bed counter-current gasification process. It was concluded that the FactSage model developed, compared with HT-XRD experimental results and that the FactSage thermodynamic modeling sup-plies insight into specific mineral reactions and slag formation. The specific value for Sasol in using FactSage, in combination with HT-XRD is that it can be used to analyze equilibrium conditions for reactions occurring between inorganic and organic materials together, as well as to provide insight into mineral transformation and slag formation. The purpose of the present study was to improve the current FactSage modeling approach, by combining specific zones in the gasification process. This can improve and speed-up the interpretation of mineral matter transformations and flow properties of reacted mineral matter in coal and assist in identifying and quantifying slag formation in the gasifier operation at temperatures not reflected by normal AFT analyses. The updated and improved FactSage model compared favorably with the original model as well as with HT-XRD results and thus will be able to supply results in a faster and more convenient manner. In the new FactSage model, supported by HT-XRD experimental findings, it is indicated that feldspar formation (including anorthite) correlated with slag formation at temperatures around 1000°C and no slag formation in the base case coal was observed in the drying and devolitilization zone, as was to be expected. Feldspar is one is the mineral species which has the lowest AFT causing the most slag-liquid formation and forms probably as a product between the SiO2, Al2O3 and Ca-containing species. In the gasification zone it was clear that slag-liquid formed at a temperature of 1000°C, with a decrease in the feldspar content. Mullite formation was also observed in the base case sample in the temperature range 1000°C and 1100°C. The decrease in the amount of SiO2 at 1100°C is related to the formation of mullite, but also that the slag-liquid phase also contains an amount of SiO2 in the molten form.

Jan 1, 2014

By E. Guerrini, M. Maccagni, J. Nielsen

"The solution for the treatment of the EAFD has not yet been fully achieved. Some of this dust has still not found an appropriate final destination. Large consortium treatment plants are quite expensive both in terms of investment and operating cost. Meanwhile, the tolling expenses for steel production companies are becoming very important, causing them to look for alternatives. Some steel plants are looking to close their production loop by internal treatment of their dust. Some years ago, Engitec began studying the coupling of the EZINEX® Process, an ammonium chloride electrolysis to recover the zinc contained in the EAFD, with the INDUTEC® Process, a pyro process based on an induction furnace that can convert EAFD into a C.Z.O. similar to the Waelz oxide. The combination of these two processes provides an alternative to the existing treatment options and is particularly interesting for relatively small capacities. In this paper, we would like to give the latest update about these two processes and their possible integration INTRODUCTION Zinc is contained in numerous wastes and secondary raw materials that can be thought of as high zinc concentrate mines. This is a very interesting source of Zn that is typically easily exploitable. Unfortunately, only a portion of these materials are currently processed to recover the metal value, while stabilized or unstabilized landfilling is often the final destination. Pyrometallurgical processes are mainly used to convert the zinc into crude zinc oxide (CZO). The various processes are very similar and characterized by the fact that the zinc bearing materials are usually submitted to a thermal treatment [1] in which the zinc is reduced, vaporized and re-oxidized producing CZO. This material not only contains zinc oxide, but also relatively high concentrations of heavy metals. Many potential CZO sources, such as electric arc furnace dust (EAF), galvanizing ashes, brass foundry and converters fumes also contain chlorides, fluorides and alkali metals that will transfer to the CZO. The classic example is the Waelz oxide [2]. This CZO is an intermediate product that must be transformed into zinc salts or zinc metal. Until now, the conversion to zinc metal is done through two main processes: the sulphate leaching and electrowinning system and the Imperial Smelting Process (ISP). ISP is facing a crisis for technical and economic reasons that has led to the closing of most of the existing plants. In any case, before being fed to one of these two processes, the CZO must be treated to eliminate or reduce some of the contained impurities. In particular, the halides are most harmful to these processes."

Jan 1, 2018

By E. Guerrini, M. Maccagni, J. Nielsen

"The solution for the treatment of the EAFD has not yet been fully achieved. Some of this dust has still not found an appropriate final destination. Large consortium treatment plants are quite expensive both in terms of investment and operating cost. Meanwhile, the tolling expenses for steel production companies are becoming very important, causing them to look for alternatives. Some steel plants are looking to close their production loop by internal treatment of their dust. Some years ago, Engitec began studying the coupling of the EZINEX® Process, an ammonium chloride electrolysis to recover the zinc contained in the EAFD, with the INDUTEC® Process, a pyro process based on an induction furnace that can convert EAFD into a C.Z.O. similar to the Waelz oxide. The combination of these two processes provides an alternative to the existing treatment options and is particularly interesting for relatively small capacities. In this paper, we would like to give the latest update about these two processes and their possible integration INTRODUCTION Zinc is contained in numerous wastes and secondary raw materials that can be thought of as high zinc concentrate mines. This is a very interesting source of Zn that is typically easily exploitable. Unfortunately, only a portion of these materials are currently processed to recover the metal value, while stabilized or unstabilized landfilling is often the final destination. Pyrometallurgical processes are mainly used to convert the zinc into crude zinc oxide (CZO). The various processes are very similar and characterized by the fact that the zinc bearing materials are usually submitted to a thermal treatment [1] in which the zinc is reduced, vaporized and re-oxidized producing CZO. This material not only contains zinc oxide, but also relatively high concentrations of heavy metals. Many potential CZO sources, such as electric arc furnace dust (EAF), galvanizing ashes, brass foundry and converters fumes also contain chlorides, fluorides and alkali metals that will transfer to the CZO. The classic example is the Waelz oxide [2]. This CZO is an intermediate product that must be transformed into zinc salts or zinc metal. Until now, the conversion to zinc metal is done through two main processes: the sulphate leaching and electrowinning system and the Imperial Smelting Process (ISP). ISP is facing a crisis for technical and economic reasons that has led to the closing of most of the existing plants. In any case, before being fed to one of these two processes, the CZO must be treated to eliminate or reduce some of the contained impurities. In particular, the halides are most harmful to these processes."

Jan 1, 2018

By X. W. Zhang

Mica plate is broadly used in electric industry, production of man-made mica paper plate is in-creasing. The problem coming with is that large quantities of leftover materials unable to be re-cycled are produced during cutting and molding of mica plate productions. The leftover materials are always abandoned as crabs, which not only pollute the environment but also waste our resources. The study intends to find a new measure to decompose and to reuse the mica plate leftover materials so as to create a new production process of mica plate, which is clean and does not produce crabs.

Jan 1, 2014

By Chuanyao Sun, Longli Liu, Fayu He, Guiye Wu

Utilizing thioglycolic acid (TGA) as a template and using structure-guided design, a molecular modelling approach has been used to design and screen appropriate dispersant for chalcopyrite. A series of organic dispersants based on a TGA substitution with hydroxyl and amino and sulfonic functional groups have been examined on chalcopyrite surface. 20 organic depressors of chalcopyrite have been investigated to study the quantitative structure-activity relationship (QSAR) of chalcopyrite depressors. For the chalcopyrite surface, depressor containing carboxyl and sulfonic group is generally stronger than the depressor containing hydroxyl group. Increasing the number of hydrophilic group can effectively enhance the inhibition. Increasing the number of Solidophilic group does not necessarily lead to enhanced inhibition ability; steric factor is one of the important factors to affect the interaction. Extension alkyl carbon chain length cannot enhance the interaction of depressors. Isomers principle as well as applies to the chalcopyrite depressor molecular design. Flotation verification tests further confirmes the accuracy of the molecular simulation. Through the Computer Aided Molecular Design (CAMD) technology, we can save enormous time and resources to design novel surfactants. This research and application will play a great significance role in sulfide flotation.

Jan 1, 2014

By M. Evertsson, M. Johansson

"In minerals processing control is vital to increasing performance and output of a plant. Model predictive control (MPC) is one of the most effective control strategies used in process industry. Sbárbaro (Sbárbaro and Del Villar, 2010), Asbjörnsson (Asbjörnsson, 2015), and Légaré (Légaré et al., 2016) have for example highlighted the possibility to simulate, develop and tune control systems using plant simulators within minerals processing. In more recent years the use of model predictive controllers have increased, and many process industries now utilize more advanced control methods to regulate their processes, raising the question regarding how to, build, test and verify a proposed control solution successfully. In this research, a linear model predictive controller is formulated and applied to a simulator of an existing tertiary crushing circuit. The circuit has in previous work by Johansson (Johansson, 2017) been modeled in MATLAB Simulink and calibrated relative plant data to an average error of less than 10% over 8 hours of production. The work demonstrates how to formulate the controller model structure to describe conveyor belts, storage components, screens, crushers, and control objectives for a minerals processing circuit. The work illustrates how to apply and successfully evaluate possible upsides in a circuit. The advantage of a crushing circuit simulator is that it can be configured, tuned and modified in any possible way, which is of great benefit to developers and engineers. Additionally, examples of how to use estimated measures to improve the performance of the plant are demonstrated. The control performance is finally evaluated for three different controller configurations."

Jan 1, 2018