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By F. Karakas

Organo-bentonite production enjoys important applications including solvent based paints and, more importantly, the production of polymer/bentonite nanocomposites. Quarternary ammonium salts in this regard are still considered as the most versatile reagents in the process of hydrophobization. In this study, a purified form of Resadiye region bentonites, which is one of the most significant sodium bentonite deposits in the world, was used. The raw Na-Bentonite was typically characterized by chemical analysis, XRD and DTA analysis and more importantly for its cation exchange capacity (CEC). Other technological properties such as swelling index, pH, apparent viscosity, water absorption, oil absorption were also conducted on the raw bentonite. The mineralogical analysis of the raw bentonite reveals that it contains about 80 % montmorillonite together with other associated gangue minerals including feldspar, quartz, calcite, dolomite, coloured impurities and other clay minerals. The raw bentonite was subjected to two stage processing involving a series of hydrocylones. Different apex and vortex diameters and different pressures were employed in order to produce a bentonite concentrate with 95 meq/100g CEC from a CEC of 71 meq/100 g. This high quality concentrate was used in the production of organo-bentontonite. The modification was performed with two different quaternary amines, i.e. Trimethyl Phenyl Ammonium Chloride (TPAC) and Hexadecyl Trimethyl Ammonium Bromide (HDTMA-Br). In the modification procedure, three parameters, i.e., adsorption density, zeta potential, swelling index and apparent viscosity were studied simultaneous-ly from the same suspension to identify both the mechanism of the process and also the degree of hydrophobicity. Adsorption measurements were made as a function of conditioning period, pH, and reagent concentration. Simultaneous examination of the adsorption density, zeta potential and apparent viscosity enabled us to pinpoint the optimum region of hydrophobicity which was subsequently tested by settling and critical coagulation concentration in both water as polar and toluene as nonpolar solvents. The results are analyzed in the light of experimental data.

Jan 1, 2014

By Sanchita Chakravarty, Sumantra Bhattacharya, Divya Jyoti, A. K. Mukherjee, Soni Jaiswal

"Release analysis is independent of collector and frother dosage and type, but it is primarily influenced by the degree of liberation or “state of release of the sample”. The shape of release curve is an indication of the degree of liberation. This paper briefs about the effect of reagent combination, particle size and surface characteristics on the release analysis of difficult-to-clean LVC coal.Release analysis of three LVC coal fines obtained from two different coalfields of India was carried out at three different size levels such as -0.5mm, (-0.5+0.1) mm, and -0.1mm. The collectors used were n-dodecane and commercial diesel oil. Incomplete liberation of coal fines even at a size of -100µm, corroborated by photomicrographs of ROM and clean coal macerals, in a great measure reduced the flotation-based cleaning potential of the fines. FESEM images of fines reveals that the adherence of ultrafine onto the surface of relatively coarser particles reduced the clean coal recovery. The results obtained also appear to be coal, reagent combination and, particle size and particle surface specific. Only one coal indicated the liberation as is usually expected for -0.1mm particles with a reasonable yield of 65% at 18% ash. INTRODUCTION Froth flotation has a long history of being used to treat coal fines. Coal flotation is considered to be difficult, if the percentage of Near Gravity Material (NGM), i.e. essentially locked particles, in flotation feed is >10% [Aplan, 1993], which is usually the case with all the coking coal fines in India. The fines are rich in vitrinite, so valuable for coking coal. Unfortunately, there appears to be no standard procedures to determine the separation efficiency of froth floatation. Release analysis proposed by C.C. Dell in 1953 [Dell, 1953], aimed to determine the ultimate floatability of coal. Several other techniques had been proposed but release analysis technique has been considered to be a vast improvement over the batch flotation process [Forrest et al. 1994]."

Jan 1, 2018

By I. Gombköto, G. Mucsi, S. Nagy, F. Kristály, Á. Rácz, R. Szabó, B. Egyed

"Present paper deals with the investigation of a Hungarian pumice. Grinding experiments were carried out in a stirred media mill for various residence time. Ground samples were tested with laser particle size analyzer to determine and calculate the material fineness (particle size distribution and specific surface area). The lime adsorption capacity was measured to monitor the reactivity. Alkali activated cement paste was prepared using ground pumice with various alkali activators. Cube shaped specimens were produced from the paste and the uniaxial compressive strength was measured at the age of 7 days. The resulted alkali activated material structure was investigated by XRD and FTIR. The results of the experiments show that pumice fineness has strong impact on its hydraulic activity, hence on the compressive strength and the structure of the resulted binder. Relationships between grinding fineness, material structure and strength of the raw and mechanical activated material as well as the alkali activated cement were revealed. INTRODUCTION Pumice is a natural pozzolan which can be used as raw material for cementitious materials in limited portion owing to its low reactivity. Furthermore, due to its mineralogical composition it can be used for developing a new environmental friendly binder, namely alkali activated cements (AAC) which are inorganic alumina-silicate materials with good cementitious properties (Almalkawi et al., 2017; Özodabas and Yilmaz, 2013; Najimi et al. 2018; Yadollahi et al., 2015). Despite being a rather recent research topic, many papers and books have been published focusing on various aspects of alkali activation. There is great variety of raw materials that can be utilized for AAC production. However, primary raw materials are very expensive and secondary materials are heterogenous in composition. Therefore, a more homogeneous and low price silicate would help to balance the properties and cost of resulting cement and easing the way for commercialization of AAC. However, the control of its reactivity is of great importance which can be realized using mechanical activation by grinding (Juhász and Opoczky, 1990; Djobo et al., 2016; Mádai et al., 2015). The goal of present paper is to investigate the effect of mechanical activation of pumice on the properties of the resulted alkali activated cement."

Jan 1, 2018

By S. Patra, R. Venugopal

"The quality of pellets produced is affected by quality anssastd quantity of green pellets, amount of addition of binders, type of binders added, amount of moisture added along with the other variables like rotation, inclination and fineness of feed. The green pellet quality depends upon chemistry, mineralogy and granulometry of fines used for pellet making, the feed size, its moisture content and porosity. During firing of green pellets ingredients present within reacts to form different phases and microstructure. So in turn physical and metallurgical properties of pellets are influenced by amount and type of binder and flux addition, induration time and temperature. During iron making process, the metallurgical properties of fired pellets are decided by the type and amount of these phases and their chemistry. Green pelletizing and induration studies have been already carried out with hematite ore fines. Indian iron ores of high alumina content showing different pelletizing characters, these studies can’t be directly interpreted. The main objective of proposed research work is to understand the green pelletizing process and determine the water bentonite interaction at different levels. Detailed investigation on swelling behavior of bentonite and microstructure of the green pellets of iron ore fines from SAIL captive iron ore fines from the Barsua in the state of Odisha. To convert these ore fines into pellets, the key raw material, additives and process variables that influence the pellet quality needs to be identified.INTRODUCTION Pelletization is the unit operation of agglomerating iron bearing fines (generally below 150µ with 65-80% passing 40µ) by tumbling in horizontal rotating drums or inclined discs, (Sivrikaya and Arol, 2013; Bhuiyan et al., 2011; Forsmo et al., 2006; Sastry et al., 2003) and the pellets are approximately spherical lumps formed by this process in presence of water and binder, on subsequent induration at 1300°c (Sivrikaya and Arol, 2014; Sivrikaya and Arol, 2013; Sivrikaya and Arol, 2012; Sivrikaya and Arol, 2010; Sastry et al., 2003; Kawatra and Ripke, 2003; Iveson, 2001a; Iveson, 2001b)."

Jan 1, 2018

By W. Z. Yin

With increasing of mining depth, many iron ores in Liaoning Province contain carbonates such as siderite and ankerite. The emergence of these carbonates in ores creates a fatal impact on the running producing process of anionic reverse flotation in Dong Anshan Sintering Plant, which leads to ?concentrate and tailing no separated?. And its reason is still unknown. Moreover, siderite, despite that its ferric theoretic grade is only 48.2%, however, do not affect the blast furnace utilization factor, therefore, can be used as raw materials in ironmaking. In order to solve the separate problem of iron ore containing carbonates, five pure minerals, martite, magnetite, quartz, siderite and ankerite, were selected for a series single flotation experiment. The aim was to discover the flotation difference of these minerals, furthermore, to explore a new flow sheet for the iron ore containing carbonates. The results of single mineral flotation experiment reveal that the combination regulators, starch and CaCl2, in different pH extent, can make these minerals taking on obvious flotation difference, which make it possible to process the iron ore containing carbonates. A new flow sheet, step-flotation, to process iron ore containing carbonates is explored, that is, first step, direct-flotation processing, is to eliminate the bad effect that the carbonates bring in flotation system by collecting carbonates under neutral condition; the second step, reverse?flotation processing, is to get qualified iron concentrate by collecting quartz under alkaline condition. Manual mixed ore sample were processed successfully through this new flowsheet under proper reagent system, which has absolute advantage compared with routine flowsheet. Actual ore sample of compound magnetic separation concentrate were processed successfully both open and closed circuit experiment through this new flowsheet. SEM and EDS were used to probe the reason why carbonates affect the regular processing. It is analyzed that moderate floatability of siderite and its coating on the surface of hematite and quartz make the phenomenon ?concentrate and tailing no separated?. This research provides a reasonable processing scheme for iron ores containing carbonates and can be used for reference in processing other complicated, refractory iron ore.

Jan 1, 2014

By H. L. Liu

With the exploitation of mineral resources, valuable minerals are more and more finer and poorer. Priority reclaiming liberation grind particle under rough grinding, will help to pervert loss of melts, raise dewatering efficiency of concentrate, reduce consumption of reagent. And it is propitious to reduce energy consumption and raise the utilization rate of resources. With the feature of coarse particle?s desorption and deposition, CLF flotation machine has special pulp circulating way, which is not only apply to treat coarse particle but also normal size particle. The paper advanced the history, the design principle, the structure feature and the application of CLF flotation machine.

Jan 1, 2014

By Dmitriy Kim, Natalya Ibragimova, Galina Sedelnikova

Gold and copper are lost in flotation tailings in mineral processing of copper-zinc-pyrite ores. Large resources of precious and base metals have accumulated in tailing ponds of Russian plants. Object of the study is the sample obtained from Ural Mining and Metallurgical Company in Russia. The main constituents in flotation tailings are Au, Ag, Cu and Zn with content 1.4 g/t, 12 g/t, 0.66 and 0.5% respectively. The flotation tailings are a refractory material. Gold, as main metal, is fine encapsulated in sulfides, mainly in pyrite. Gold extraction from tailings is 34.0 and 42.7% at P42 and P90 of 0.074mm particle size respectively. In this work heap bioleaching of tailings was studied for oxidation sulfides (pyrite and chalcopyrite) with using mesofilic and moderately termofilic bacteria in acidic solutions. The tailings had low filtration property (< 0.3 m/day) and pelletization was used before bioleaching. Copper containing converter slags flotation tailings and calcium oxide were used as binding material for increasing filtration property of tailings. Copper was extracted in sulfate solution and was precipitated by cementation after cleaning of bacterial solution from iron. Copper recovery was 56.8% at content 61.4% in precipitate. The biooxidation of pyrite was 80%. Cyanidation, leaching with thiourea and heap leaching by cyanide were tested too. Gold extraction from solid bioresidues was 82, 75.3 and 77% respectively. The results of this investigation were recommended for pilot test.

Jan 1, 2014

By B. Orberger, J. M. Milazzo, S. B. Blancher, J. Lützenkirchen, J. L. Dubos

"Industrial dusts are commonly agglomerated using empirical recipes with binders such as bentonite, while Sludges are agglomerated into mixes. Those materials contaminate the products, are expensive and generate significant amounts of slag. Achieving cold dust agglomeration with little or no binder requires understanding the controlling parameters in order to predict and optimize the process behavior. This in turn necessitates comprehensive dust characterization to base predictions on measurable characteristics. In the present work we collected 13 Mn-rich dusts over all the process chain: feed fines, smelting, and refining dusts, as well as ferromanganese alloy dust. This is the first systematic study of dusts along the Mn-processing chain for chemical, physical and mineralogical parameters. X-Ray Diffraction, Qemscan® and laser granulometry analyses show that the mineralogy, Particle Size Distribution (PSD) and morphology evolves from complex heterogenous to simple, homogenous along the process chain: The mineralogy of the primary ore dusts shows various hydroxides, oxides, carbonates, tectosilicates and phyllosilicates. The furnace dusts contain oxides, tectosilicates and carbonates with volatiles, while the refining dusts present only oxides and metal. Finally, the Metal dust is nearly pure metal. Particle morphologies and PSD vary from jagged, irregular particles with broad PSD (>1 mm to <0.3 µm) to smooth and spherical with narrow PSD (100 µm to <0.3 µm). The Metal dust is an exception with angular particles. The Cationic Exchange Capacities (CECs) of all samples range from 0 to 22 meq/100g. Specific surface areas (SSAs) range from <0.1 to 27m²/g, and seem to decrease with from ore feed to Metal dust. This may be due to the disappearance of hydrated and/or sheet-bearing minerals, since a smaller grain size usually implies an increased SSA. The zeta potential varies strongly over the range of the samples tested. However, beside the Gabon ore which has an Isoelectric Point (IEP) ~ 4.1, the other IEP ranges between 2 and 2.5."

Jan 1, 2018

By J. D. Miller, C. L. Lin

In general, x-ray computed tomographic (CT) techniques are able to provide 3D images of the internal structure of opaque materials in a nondestructive manner. The unique cone beam geometry allows acquisition of all 2D projections with only one rotation of the sample thus providing for fast data acquisition and better x-ray utilization, as a complete 2-D detector array receives the cone-shaped flux of rays. Thus, an isotropic 3D volume can be reconstructed without the mechanical translation and the stacking of sequential slices as is the case for more conventional CT scanners. In this regard, a state-of-the-art, custom designed xray microtomography facility to provide very detailed 3D spatial analysis of multiphase particles has been installed and is in operation at the University of Utah. The reconstructed 3D tomographic volume allows for an adjustable spatial resolution from 5 to 20 microns for sample dimensions from 10 to 40 mm in diameter, respectively. Utilization of this custom designed cone-beam x-ray microtomography system is discussed. Applications described include: coal washability analysis for the design and operation of coal preparation plants, liberation analysis for evaluation of grinding practice and separation efficiency, mineral exposure analysis for prediction of the ultimate recovery from heap leaching operations, and analysis of the pore structure network of packed particle beds for simulation of flow through such porous structures as encountered in filtration and heap leaching.

Jan 1, 2003

By Anand Anupam

Conventionally, beneficiation in Indian coal washeries is done using dense medium cyclones upto the size of 0.5 mm. Coal fines below 0.5 mm size are extensively cleaned by froth flotation. There are many problems associated with flotation of Indian coals, e.g. poor response of coal particles to flotation, misplacement of fine high-ash material to froth, loss of good quality coarser coals (within ?0.5 mm size range) to tailing streams, high cost of reagents, water contamination, etc. In addition, sophisticated control systems for efficient management of the fines washing circuits are needed. Thus, there is an escalation in the capital and processing costs. In view of these facts, studies were carried out to establish the cleaning potential of dense medium cyclones for beneficiation of fine coal down to a size of 0.1 mm, essentially aimed at reducing the load on fine coal circuits mainly comprising of flotation. ROM Coal (in the size range of -2 + 0.1 mm) obtained from JogtaOCM,Jharia coalfield possessing relatively low ash (about 21%) was used in this study. Purpose for using low ash coal was to further lower, its ash content down to 8% which is comparable, to the ash content of imported coal. After characterization studies, nine tests were carried out on the prepared feed sample for its beneficiation using a dense medium cyclone of non-conventional design (very low cone angle and longer barrel), by varying its apex and vortex finder diameters. The efficiency of separation has been evaluated using Tromp curves. It could be established that it is possible to produce a clean coal of 8% ash, with Ep value of 0.044, using Jogta OCM coal by treating it in a modified dense medium cyclone. These results are summarized and discussed in detail in the present paper. Keywords: dense medium, cyclone, fine coal, beneficiation, Jharia coal

Sep 1, 2012

By Zhang Zhonghan

A domestic tungsten-tin ore presents very complex property. How to effectively recover the scheelite, wolframite and cassiterite in the ore has long been a difficult problem to be solved urgently. On the basis of process mineralogy study, a main flow-sheet for effective recovery of tungsten-tin minerals has been developed, which including ?fine grinding of feed?bulk flotation of all sulfides followed by their selective separation?iron recovery by LIMS?tungsten-tin minerals bulk flotation using new technique developed by our institute?tungsten-tin recovery by gravity from above tungsten-tin bulk flotation tailings?. As for the treatment of tungsten-tin bulk rougher concentrate, several flow-sheets of tungsten-tin separation by direct hydrometallurgy or a flow-sheet consisting of scheelite cleaning at elevated temperature followed by the gravity separation of scheelite cleaner tailing?separation of wolframite from cassiterite by dry HIMS or by direct hydrometallurgy are developed. For a low grade head ore, all valuable sulfide, magnetite, scheelite, wolframite and cassiterite are recovered with satisfactory in lab scale test. Keywords: micro-fine cassiterite, tungsten-tin bulk flotation, gravity separation-flotation-dry HIMS combined flow-sheet, hydrometallurgy

Sep 1, 2012

By V. I. Ryaboy, I. V. Ryaboy, E. D. Shepeta

"The problem of separation of copper minerals and arsenopyrite remains relevant because of environmental requirements. The selective action of reagents with the thioamide group (thioamides) is known in iron sulfide’s flotation of pyrite and pyrrhotite. The aim of this study was to reduce the arsenic content in the copper concentrate when using thioamides by reducing the flotation of arsenopyrite in the flotation of the sulfide part of the skarn scheelite-sulfide ores. We have chosen the most widely used thioamides for the study, such as Z-200. We also synthesized new reagents with the thioamide group. The most selective and the most powerful thioamide copper collector were used for further studies. Reduction of arsenic content in copper concentrates is achieved in the following way: You need to apply a strong thioamide collector with a selective but weak dialkyldithiophosphate collector, or vice-versa, a selective, but a weak thioamide collector should be used with the dialkyldithiophosphate reagent with strong collective properties. The proposed combination presents industrial interest because of its accessibility. The application of thioamides in copper minerals and arsenopyrite selection has showed that these reagents have fewer selective properties than dialkyldithiophosphates. To achieve the comparable recovery of copper using dialkyldithiophosphates requires markedly greater consumption of thioamides, due to their lower hydrophobic ability. The application of a composition of thioamides and dialkyldithiophosphates allows to increase the recovery of copper and to obtain a lower arsenic content in copper concentrates compared to their individual use. The lowest arsenic content in the copper concentrate is obtained in the composition consisting of the newly synthesized thioamide with strong collective properties and selective dialkyldithiophosphate. The addition of even small amounts of xanthate to the composition of thioamides and dialkyldithiophosphates causes a sharp increase in the arsenic content in the copper concentrate without a notable increase in copper recovery."

Jan 1, 2018

By A. S. Chekmarev, T. Z. Lygina, K. G. Egorova, A. V. Skvorcov

"We have conducted analytical and technological evaluation of sepiolite containing clay. The possible areas of application of the sepiolite have been investigated and complex methods of enrichment of natural sepiolite have been identified. It was determined that for preserving the structure of minerals after processing the most effective method of the natural agglomerates disintegration was the soft abrasion of the clay fraction up to 0,5 mm. Disintegration of sepiolite clay along with using high energy-stressed effects on the matrix can deteriorate the rheological properties of clay suspensions and reduce the yield of drilling mud and sorption properties. To improve the quality of clay powders we used combined gravity-modifying method of wet enrichment. After the wet enrichment the yield of drilling mud increased up to 12.7 m3/t, with the addition of MgO up to 20,3 m3/t. It was noted that drilling muds contenting more than 50% of sepiolite are stable in mineralized (salt) waters. Based on the studied activated sepiolite rocks we obtained the effective heat-insulating materials with relatively low thermal conductivity – 0,165 W/m·K, average strength – 7,29 MPa and water absorption-49,0%.INTRODUCTION The modern development of the Russian economy requires the implementation of scientific and technical tasks. The solutions of it involves a radical reduction in energy, heat losses and material consumption of products, rational and efficient using of all types of resources, as well as the using of new types of mineral raw materials and materials based on it. An example of a new type of mineral raw materials for Russia is sepiolite containing rocks, due to unconventional conditions for their soils accumulation in the climate of the Far North. Sepiolite is a unique type of nonmetallic mineral. It is formed in soils, marine and saline basins, occurs in carbonate and carbonate-clay rocks in the form of lenses and lens – shaped layers, rarely nodules, loose powdery masses, shell-like concretions. Sepiolite may have a soft porous macroscopic appearance or less often the structure of the fibrous mass. Color of sepiolite is from white to cream with gray, green, pink and even crimson shade depending on the degree of pollution. Sepiolite can be in two forms - a-sepiolite (parasepiolite), which occurs in the form of large packets of crystalline fibers and ß-sepiolite, which occurs in the form of amorphous aggregates or small flat rounded particles. The sepiolite fibers have a length of from 0.2 to 2 Å, width from 100 to 300 Å, the thickness from 50 to 100 Å (Geological dictionary, 1973)."

Jan 1, 2018

By V. F. Petrov, E. P. Olberg, S. V. Petrov

"The study was carried out using process solutions produced during cyanidation of gold-bearing concentrates from a gold-processing plant. It was found that the water contained a significant portion of thiocyanate (7910.0 mg/L), cyanide was virtually not present. The metals occurred primarily as iron (355.0 mg/L) in the form of ferrocyanide. Cyanide recovery was conducted using an ozone treatment process with reactors developed by the Environmental Department of Irgiredmet. The process design ensured complete utilization (100%) of O3, thus equipment operation safety increased.The recovery of free cyanide from thiocyanate was 76.6%, which corresponded to 5.12 kg of NaCN (100%) per 1 m3 of solution. Recovered NaCN can be used for recycling in hydrometallurgical processes.The operating costs estimation showed that the production cost of a tonne of recovered cyanide was US$1288.7, considering the prices of energy and commercial sodium cyanide in Russia in 2017, i.e. recovered cyanide is cheaper than commercial cyanide by 55.8%.INTRODUCTION Depletion of oxidized gold-bearing ores readily amenable to cyanidation has shifted focus to large-scale processing of primary ores with high sulphide content. Primary ores processing flow sheets involve gravitational and/or flotation concentration with subsequent treatment of produced gold-bearing concentrates. Typically, concentrates reporting to cyanidation contain considerable amounts of sulphur that can interact with CN- and further formation of SCN-. The use of refractory gold liberation methods (bacterial liberation, ultra-fine grinding) provides activation of this side reaction up to complete consumption of free cyanide in a short period. This makes water recycling unviable and impractical.The interaction of the sulphur content in concentrates and cyanide contributes substantially to consumption of NaCN required for efficient gold recovery. Inappropriate consumption of the main reagent achieves dozens of kilogram per tonne of material to cyanidation, and reaches approximately 100% when gold is recovered from activated sulphide-containing products (e.g. by ultra-fine grinding)."

Jan 1, 2018

By E. T. Tuzcu

In this manuscript, a new approach for modeling the rate of grinding process is explained. A review about grinding rate definitions so far is given and the possible ultimate way for grinding modeling is given as modeling the rate based on energy spectra. The traditional/phenomenological approaches for modeling size distribution of grinding mills give their place to a new generation modeling technique. Developments in the computational methods and necessity to model product size distribution of large mills, larger than ball mill size, paved the way for this novel technique. The traditional grinding rate models are mostly based on the back calculated breakage parameters from the experimental data. However, direct modeling of breakage parameters and hence the prediction of size distribution of the grinding mills may become possible with this approach. The material breakage data and discrete element method (DEM) energy spectra are the main components of this approach. Albeit the focus in this study is on modeling of breakage rate under impact mode of breakage, the abrasion mode of breakage was also tested by carrying out abrasion tests. Impact mode of breakage was analyzed using ultra-fast load cell device (UFLC) and drop weight tester. Dry tumbling test was carried out for abrasion experiments. Obtained material breakage versus energy data are combined with the collision energy spectra to obtain the breakage rate function. In addition, the material breakage versus energy information from the tests is converted into breakage distribution function. The model was verified in a lab scale mill (90 cm diameter-15 cm length). 10 to 15 kg of limestone was ground using 50 mm steel ball at varying conditions, i.e., rpm, volume loading. It is shown that the proposed model predicts all (1, 2, 4 min.) grinding intervals for all experiments highly accurate.

Sep 1, 2012

By H. R. Manouchehri

Sustainable development requires the optimal use of natural resources and recycling of the wastes. In fact recycling is the final productive use of obsoletes. ELVs, obsolete appliances and industrial wastes have become important resources for production of iron and steels, non-ferrous metals, and composites. Within shredding plants, these obsoletes are firstly shredded to the pieces and then processed to recycle different materials, especially ferrous and non-ferrous metals for metallurgy. Traditional and new developed mineral processing technologies are nowadays used for recycling different materials from waste effluents. Shredding and separating plants are currently recycle the wastes by make use of different technologies to mainly produce raw material for metallurgical application. However, other non-ferrous components are also treated for energy conservation and protecting environment. Currently, recovery in shredding and recycling plants maximises to 75% and about 25% of the feed is land-filled. However, recycling rate must be increased in due to the economical, environ-mental and social concerns. A comprehensive study for recycling, with especial focus on ferrous metal recovery, was sup-ported by Swedish Environmental Agency (MISTRA) to look at possibilities to increase the recycling rate and to reduce the amount of disposal. Part of this study was dedicated to study the shred-ding plant facilities and to look for possibilities to improve the quality and quantity of the shredding product streams. The aims were to improve the quality of ferrous scrap (apparent density > 0.9 and Cu<0.25%) for iron and steel production as well as having better quality for non-ferrous metals through the recycling schema, and finally to treat the shredder residue (SR) to recover metals and plastics to reduce the disposals. This paper summarises the results of sampling and conducting separation tests for improving the recovery of the ferrous and non-ferrous metals. The results indicated to be possible to obtain high quality ferrous scrap at recovery of 88%. However, the total recovery for metal scrap has reached 93%. Furthermore, test results on fine, P< 8mm, shredding residue (SR) showed promising prospect in recovery of metals and protecting environment by physical separation, i.e. electrical separation technique.

Jan 1, 2014

By Y. Y. Li, T. T. Yang, R. X. Zhou, Z. H. Shen

"Wetting theory is one of the basic theories of flotation. The effects of concentrations, carbon chain length and pH values of saturated fatty acid collectors (lauric acid, myristic acid, palmitic acid and stearic acid) on the surface wettability of collophanite and dolomite were investigated by measuring the contact angle with dynamic captive-bubble technique and calculating adhesion work of bubble-mineral. The results show that the contact angles both of collophanite and dolomite are higher with enhancement of hydrophobicity when pH value of 5~9. The contact angles both of collophanite and dolomite are reduced with improvement of surface hydrophilicity. When strong acid pH value of 2~4 or strong alkaline pH value of 10~13. The reasons for this are that the fatty acids mainly exist with insoluble RCOOH molecules in strong acid condition, and competitive adsorption of OH- and RCOO- in the mineral surface is formed in strong alkaline condition. With the increase of the collector concentration, the contact angles of the collophanite and the dolomite all first increase then decrease. The formation of hydrophilic micelles results in the decreasing of contact angles and enhancement of surface hydrophilicity opposite when the collector concentration exceeds CMC. The contact angles of the collophanite and dolomite and the WSG of the bubble adhesion increase, the hydrophobicity enhance with the increasing of carbon chains of saturated fatty acid from 12 to 18. The variation tendency for the adsorption quantity of collectors and floatability of collophanite and dolomite are in line with the change trend of contact angle basically. It shows that the wettability of solid-liquid-gas interface can be well characterized by the dynamic captive-bubble technique.INTRODUCTIONPhosphorite resources are the main raw material for producing phosphate fertilizer and producing phosphoric acid (Cao et al.,2005), which is an important strategic mineral resource. The useful minerals in calcareous-magnesium phosphate ore are collophanite, and the main gangue minerals are dolomite (SISH et al.,2003). The lattice ions of the phosphorite and dolomite are both Ca2+, their similar surface properties and similar floatability are the main reason for the flotation of calcareous-magnesium phosphate ore difficultly (Fang et al.,2011). Usually, fatty acid collectors are used for the flotation of calcareous-magnesium phosphate ore under acidic conditions by reversing flotation method to remove dolomite (ABOUZEID et al.,2009), or direct flotation is used to gather collophanite in the alkaline conditions (Gong et al.,2017). The flotation behavior of collophanite and dolomite affects the indexes of concentrate and flotation efficiency directly. Therefore, it is necessary to study the action mechanism and the flotation method of the collector with the phosphate rock and dolomite respectively (Moudgil et al.,1988; Hanna, et al.,1990)."

Jan 1, 2018

By Jaeheon Lee, Jae-Chun Lee, Doyun Shin, Minseuk Kim, Hyunsik Park

"The appropriate treatment of cyanide waste water is becoming an emerging issue because of the toxic residue and large quantity produced from gold processing plants. In the present article, we designed and operated a continuous biological cyanide treatment system using domestic sewage sludge and various microorganisms including a cyanide-producing and degrading bacterium, Chromobacterium violaceum. The synthetic wastewater containing 50 mg/L of cyanide was pumped continuously into the reactor at a flow rate of 500 mL/d for 21 days. When 50 mg/L of cyanide was fed, the cyanide concentration in the effluent of the reactor inoculated with activated sludge (S-50) decreased by 7.5 mg/L in the effluent. The other reactors did not show significant cyanide degradation and the reactor inoculated with C. violaceum showed increased cyanide concentration in the effluent. The microbial community in the reactors was analyzed by 16S rRNA-gene based pyrosequencing technique to investigate microbial response to cyanide addition and operation time. The microbial community analysis shows that the phylum Proteobacteria was detected in the reactors showing significant cyanide degradation (S-50), while Firmicutes and Bacteroidetes was dominant in the other reactors with very low cyanide degradation. Proteobacteria could not compete when the other phyla Firmicutes or Bacteroidetes were inoculated. This study shows the feasibility of the biological cyanide treatment system for gold processing plants and contributes new fundamental knowledge about the microbial community in the biological cyanide treatment system. INTRODUCTION Cyanidation has been widely used to recover gold from ores or secondary resources since first proposed by MacArthur and Forrest in 1888 (MacArthur et al., 1888) and it is used in many states of the USA, including Nevada, Arizona, California, Colorado, and Idaho (Laitos, 2012). Cyanide compounds are highly toxic and create serious problems for wildlife and water management (Solomonson, 1981; Donato et al., 2007). Furthermore, because many countries have imposed strict standards for cyanide discharge (USEPA, 1985), it is essential to develop a cost-effective and environmentally friendly technology for treating cyanide-containing wastewater."

Jan 1, 2018

By A. J. Lynch, D. K. Tungpalan, Y. Reja, E. C. Avelar, G. Figueroa, S. Gómez, R. Alanis, M. A. Corona-Arroyo

"Have you been on a mine site? This question was posed by Emeritus Professor Alban Lynch to Higher Degree by Research (HDR) Students from the Sustainable Minerals Institute - Julius Kruttschnitt Mineral Research Centre (SMI-JKMRC) in the Student Technical Presentations in 2015. From that question, five HDR students from SMI-JKMRC organised a placement on mine sites in Mexico. The SMI-JKMRC is well known for its tradition to provide their students with opportunities to enhance and test their skills in mineral processing plants. The Student Venture became a short internship for HDR students which had the objective of establishing collaboration with mining companies in Australia and overseas, and of providing a unique experience for the HDR students in regard to their training, professional development, networking and cultural interchange. In return for the companies’ support, the students conducted plant audits to evaluate the process performance thereby providing valuable data to the host company. The 2016 Student Venture was held at the Grupo Peñoles & Grupo Fresnillo in Mexico, in which three mine sites received five HDR students from JKMRC and one young researcher from Universidad de Guanajuato (UG). This paper describes the positive outcomes for the mining company and the students for this experience. The Venture was considered very successful, as it provided valuable training for the students as well as in depth information about the operation of the comminution and flotation circuits of the host sites for the Grupo Peñoles & Grupo Fresnillo. The experience also provided an opportunity for an exchange of knowledge between the HDR students and the site personnel from the host operations. The indication of the success of the experience for all involved was the support of the host company in future student internships."

Jan 1, 2018

By Zhangm Zeqiang, Manman Lu, Hanquan Zhang, Hong Yu, Jintao Fu

"Pelletizing is an important technique in the ironmaking industry. Artificial and natural magnetites are materials that are widely utilized in the iron ore pelletizing process. In this work, the pelletizing characteristics of these two types of magnetite have been investigated in detail. The obtained results shown that in contrast to natural magnetite, the artificial magnetite concentrate exhibits stronger hydrophilicity, lower electronegativity, larger specific surface area, and rougher surface. In addition, the green pellets produced from the artificial magnetite concentrate are characterized by a higher compressive strength as compared to that of the pellets obtained from the natural magnetite concentrate. However, the shock temperature of the artificial magnetite pellets around 255 C is significantly lower than the threshold specified by the industry. The balling characteristics of the material obtained by mixing 20% of the artificial magnetite concentrate with 80% of the natural magnetite concentrate are considerably improved with respect to those of the individual components.INTRODUCTION Pelletization is an essential process of the ironmaking industry in China. Since the pellets produced from iron ore exhibit high mechanical strength, good particle granularity, and uniform shapes, pelletizing high-grade iron ores with good metallurgical reducibility can lower the coke ratio, improve their technico-economic index, and reduce the cost of processing pig iron in blast furnaces[1, 2]. Presently, high-grade magnetite is a material utilized for pelletizing various iron ores across the globe. However, its natural deposits have been depleting rapidly in recent years; as a result[3], China’s dependence on the foreign high-grade iron ores exceeded 70% in 2009 and reached the level of 87% in 2016. Hence, possible methods for the efficient cultivation of limonite, siderite, hematite, and other refractory minerals that correspond to low-grade, finely sized, inhomogeneous, and scattered iron ores have attracted significant attention [4, 5]. In particular, magnetization reduction roasting and magnetic separation techniques, which are widely utilized for obtaining high-grade artificial magnetite, represent effective ways of processing iron ores that can alleviate the scarcity of natural magnetite resources [6, 7]. The artificial magnetite produced by magnetization reduction roasting exhibits different characteristics as compared with those of natural magnetite (including the degree of hydrophilicity, surface potential, specific surface area, and other surface physicochemical properties[8-11], which significantly affect its pelletizing behavior. In this work, the surface characteristics of artificial and natural magnetites are investigated in detail, and their effect on their pelletizing properties (such as green ball strength, heat stability, and pelletization rate) are examined."

Jan 1, 2018